Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1 | :mod:`socket` --- Low-level networking interface |
| 2 | ================================================ |
| 3 | |
| 4 | .. module:: socket |
| 5 | :synopsis: Low-level networking interface. |
| 6 | |
Terry Jan Reedy | fa089b9 | 2016-06-11 15:02:54 -0400 | [diff] [blame] | 7 | **Source code:** :source:`Lib/socket.py` |
| 8 | |
| 9 | -------------- |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 10 | |
| 11 | This module provides access to the BSD *socket* interface. It is available on |
Andrew Kuchling | 98f2bbf | 2014-03-01 07:53:28 -0500 | [diff] [blame] | 12 | all modern Unix systems, Windows, MacOS, and probably additional platforms. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 13 | |
| 14 | .. note:: |
| 15 | |
| 16 | Some behavior may be platform dependent, since calls are made to the operating |
| 17 | system socket APIs. |
| 18 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 19 | .. index:: object: socket |
| 20 | |
| 21 | The Python interface is a straightforward transliteration of the Unix system |
| 22 | call and library interface for sockets to Python's object-oriented style: the |
Ezio Melotti | c048d98 | 2013-04-17 04:10:26 +0300 | [diff] [blame] | 23 | :func:`.socket` function returns a :dfn:`socket object` whose methods implement |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 24 | the various socket system calls. Parameter types are somewhat higher-level than |
| 25 | in the C interface: as with :meth:`read` and :meth:`write` operations on Python |
| 26 | files, buffer allocation on receive operations is automatic, and buffer length |
| 27 | is implicit on send operations. |
| 28 | |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 29 | |
Antoine Pitrou | e1bc898 | 2011-01-02 22:12:22 +0000 | [diff] [blame] | 30 | .. seealso:: |
| 31 | |
| 32 | Module :mod:`socketserver` |
| 33 | Classes that simplify writing network servers. |
| 34 | |
| 35 | Module :mod:`ssl` |
| 36 | A TLS/SSL wrapper for socket objects. |
| 37 | |
| 38 | |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 39 | Socket families |
| 40 | --------------- |
| 41 | |
| 42 | Depending on the system and the build options, various socket families |
| 43 | are supported by this module. |
| 44 | |
Antoine Pitrou | 6ec29e2 | 2011-12-16 14:46:36 +0100 | [diff] [blame] | 45 | The address format required by a particular socket object is automatically |
| 46 | selected based on the address family specified when the socket object was |
| 47 | created. Socket addresses are represented as follows: |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 48 | |
Antoine Pitrou | 6ec29e2 | 2011-12-16 14:46:36 +0100 | [diff] [blame] | 49 | - The address of an :const:`AF_UNIX` socket bound to a file system node |
| 50 | is represented as a string, using the file system encoding and the |
| 51 | ``'surrogateescape'`` error handler (see :pep:`383`). An address in |
Serhiy Storchaka | 8490f5a | 2015-03-20 09:00:36 +0200 | [diff] [blame] | 52 | Linux's abstract namespace is returned as a :term:`bytes-like object` with |
Antoine Pitrou | 6ec29e2 | 2011-12-16 14:46:36 +0100 | [diff] [blame] | 53 | an initial null byte; note that sockets in this namespace can |
| 54 | communicate with normal file system sockets, so programs intended to |
| 55 | run on Linux may need to deal with both types of address. A string or |
Serhiy Storchaka | 8490f5a | 2015-03-20 09:00:36 +0200 | [diff] [blame] | 56 | bytes-like object can be used for either type of address when |
Antoine Pitrou | 6ec29e2 | 2011-12-16 14:46:36 +0100 | [diff] [blame] | 57 | passing it as an argument. |
| 58 | |
| 59 | .. versionchanged:: 3.3 |
| 60 | Previously, :const:`AF_UNIX` socket paths were assumed to use UTF-8 |
| 61 | encoding. |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 62 | |
Berker Peksag | 253739d | 2016-01-30 19:23:29 +0200 | [diff] [blame] | 63 | .. versionchanged:: 3.5 |
Serhiy Storchaka | 8490f5a | 2015-03-20 09:00:36 +0200 | [diff] [blame] | 64 | Writable :term:`bytes-like object` is now accepted. |
| 65 | |
R David Murray | 6b46ec7 | 2016-09-07 14:01:23 -0400 | [diff] [blame] | 66 | .. _host_port: |
| 67 | |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 68 | - A pair ``(host, port)`` is used for the :const:`AF_INET` address family, |
| 69 | where *host* is a string representing either a hostname in Internet domain |
| 70 | notation like ``'daring.cwi.nl'`` or an IPv4 address like ``'100.50.200.5'``, |
Sandro Tosi | 27b130e | 2012-06-14 00:37:09 +0200 | [diff] [blame] | 71 | and *port* is an integer. |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 72 | |
| 73 | - For :const:`AF_INET6` address family, a four-tuple ``(host, port, flowinfo, |
| 74 | scopeid)`` is used, where *flowinfo* and *scopeid* represent the ``sin6_flowinfo`` |
| 75 | and ``sin6_scope_id`` members in :const:`struct sockaddr_in6` in C. For |
| 76 | :mod:`socket` module methods, *flowinfo* and *scopeid* can be omitted just for |
| 77 | backward compatibility. Note, however, omission of *scopeid* can cause problems |
| 78 | in manipulating scoped IPv6 addresses. |
| 79 | |
| 80 | - :const:`AF_NETLINK` sockets are represented as pairs ``(pid, groups)``. |
| 81 | |
| 82 | - Linux-only support for TIPC is available using the :const:`AF_TIPC` |
| 83 | address family. TIPC is an open, non-IP based networked protocol designed |
| 84 | for use in clustered computer environments. Addresses are represented by a |
| 85 | tuple, and the fields depend on the address type. The general tuple form is |
| 86 | ``(addr_type, v1, v2, v3 [, scope])``, where: |
| 87 | |
Éric Araujo | c4d7d8c | 2011-11-29 16:46:38 +0100 | [diff] [blame] | 88 | - *addr_type* is one of :const:`TIPC_ADDR_NAMESEQ`, :const:`TIPC_ADDR_NAME`, |
| 89 | or :const:`TIPC_ADDR_ID`. |
| 90 | - *scope* is one of :const:`TIPC_ZONE_SCOPE`, :const:`TIPC_CLUSTER_SCOPE`, and |
| 91 | :const:`TIPC_NODE_SCOPE`. |
| 92 | - If *addr_type* is :const:`TIPC_ADDR_NAME`, then *v1* is the server type, *v2* is |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 93 | the port identifier, and *v3* should be 0. |
| 94 | |
Éric Araujo | c4d7d8c | 2011-11-29 16:46:38 +0100 | [diff] [blame] | 95 | If *addr_type* is :const:`TIPC_ADDR_NAMESEQ`, then *v1* is the server type, *v2* |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 96 | is the lower port number, and *v3* is the upper port number. |
| 97 | |
Éric Araujo | c4d7d8c | 2011-11-29 16:46:38 +0100 | [diff] [blame] | 98 | If *addr_type* is :const:`TIPC_ADDR_ID`, then *v1* is the node, *v2* is the |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 99 | reference, and *v3* should be set to 0. |
| 100 | |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 101 | - A tuple ``(interface, )`` is used for the :const:`AF_CAN` address family, |
| 102 | where *interface* is a string representing a network interface name like |
| 103 | ``'can0'``. The network interface name ``''`` can be used to receive packets |
| 104 | from all network interfaces of this family. |
| 105 | |
Pier-Yves Lessard | a30f6d4 | 2017-08-28 04:32:44 -0400 | [diff] [blame] | 106 | - :const:`CAN_ISOTP` protocol require a tuple ``(interface, rx_addr, tx_addr)`` |
| 107 | where both additional parameters are unsigned long integer that represent a |
| 108 | CAN identifier (standard or extended). |
| 109 | |
Martin v. Löwis | 9d6c669 | 2012-02-03 17:44:58 +0100 | [diff] [blame] | 110 | - A string or a tuple ``(id, unit)`` is used for the :const:`SYSPROTO_CONTROL` |
| 111 | protocol of the :const:`PF_SYSTEM` family. The string is the name of a |
| 112 | kernel control using a dynamically-assigned ID. The tuple can be used if ID |
| 113 | and unit number of the kernel control are known or if a registered ID is |
| 114 | used. |
| 115 | |
| 116 | .. versionadded:: 3.3 |
| 117 | |
Martin Panter | d1a9858 | 2015-09-09 06:47:58 +0000 | [diff] [blame] | 118 | - :const:`AF_BLUETOOTH` supports the following protocols and address |
| 119 | formats: |
| 120 | |
| 121 | - :const:`BTPROTO_L2CAP` accepts ``(bdaddr, psm)`` where ``bdaddr`` is |
| 122 | the Bluetooth address as a string and ``psm`` is an integer. |
| 123 | |
| 124 | - :const:`BTPROTO_RFCOMM` accepts ``(bdaddr, channel)`` where ``bdaddr`` |
| 125 | is the Bluetooth address as a string and ``channel`` is an integer. |
| 126 | |
| 127 | - :const:`BTPROTO_HCI` accepts ``(device_id,)`` where ``device_id`` is |
| 128 | either an integer or a string with the Bluetooth address of the |
| 129 | interface. (This depends on your OS; NetBSD and DragonFlyBSD expect |
| 130 | a Bluetooth address while everything else expects an integer.) |
| 131 | |
| 132 | .. versionchanged:: 3.2 |
| 133 | NetBSD and DragonFlyBSD support added. |
| 134 | |
| 135 | - :const:`BTPROTO_SCO` accepts ``bdaddr`` where ``bdaddr`` is a |
Martin Panter | d830262 | 2015-09-11 02:23:41 +0000 | [diff] [blame] | 136 | :class:`bytes` object containing the Bluetooth address in a |
Martin Panter | d1a9858 | 2015-09-09 06:47:58 +0000 | [diff] [blame] | 137 | string format. (ex. ``b'12:23:34:45:56:67'``) This protocol is not |
| 138 | supported under FreeBSD. |
| 139 | |
Christian Heimes | dffa394 | 2016-09-05 23:54:41 +0200 | [diff] [blame] | 140 | - :const:`AF_ALG` is a Linux-only socket based interface to Kernel |
| 141 | cryptography. An algorithm socket is configured with a tuple of two to four |
| 142 | elements ``(type, name [, feat [, mask]])``, where: |
| 143 | |
| 144 | - *type* is the algorithm type as string, e.g. ``aead``, ``hash``, |
Christian Heimes | 8c21ab0 | 2016-09-06 00:07:02 +0200 | [diff] [blame] | 145 | ``skcipher`` or ``rng``. |
Christian Heimes | dffa394 | 2016-09-05 23:54:41 +0200 | [diff] [blame] | 146 | |
| 147 | - *name* is the algorithm name and operation mode as string, e.g. |
| 148 | ``sha256``, ``hmac(sha256)``, ``cbc(aes)`` or ``drbg_nopr_ctr_aes256``. |
| 149 | |
| 150 | - *feat* and *mask* are unsigned 32bit integers. |
| 151 | |
| 152 | Availability Linux 2.6.38, some algorithm types require more recent Kernels. |
| 153 | |
| 154 | .. versionadded:: 3.6 |
| 155 | |
Martin Panter | d1a9858 | 2015-09-09 06:47:58 +0000 | [diff] [blame] | 156 | - Certain other address families (:const:`AF_PACKET`, :const:`AF_CAN`) |
| 157 | support specific representations. |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 158 | |
| 159 | .. XXX document them! |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 160 | |
| 161 | For IPv4 addresses, two special forms are accepted instead of a host address: |
| 162 | the empty string represents :const:`INADDR_ANY`, and the string |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 163 | ``'<broadcast>'`` represents :const:`INADDR_BROADCAST`. This behavior is not |
| 164 | compatible with IPv6, therefore, you may want to avoid these if you intend |
| 165 | to support IPv6 with your Python programs. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 166 | |
| 167 | If you use a hostname in the *host* portion of IPv4/v6 socket address, the |
| 168 | program may show a nondeterministic behavior, as Python uses the first address |
| 169 | returned from the DNS resolution. The socket address will be resolved |
| 170 | differently into an actual IPv4/v6 address, depending on the results from DNS |
| 171 | resolution and/or the host configuration. For deterministic behavior use a |
| 172 | numeric address in *host* portion. |
| 173 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 174 | All errors raise exceptions. The normal exceptions for invalid argument types |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 175 | and out-of-memory conditions can be raised; starting from Python 3.3, errors |
| 176 | related to socket or address semantics raise :exc:`OSError` or one of its |
| 177 | subclasses (they used to raise :exc:`socket.error`). |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 178 | |
Georg Brandl | 8569e58 | 2010-05-19 20:57:08 +0000 | [diff] [blame] | 179 | Non-blocking mode is supported through :meth:`~socket.setblocking`. A |
| 180 | generalization of this based on timeouts is supported through |
| 181 | :meth:`~socket.settimeout`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 182 | |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 183 | |
| 184 | Module contents |
| 185 | --------------- |
| 186 | |
Antoine Pitrou | a5cc9d6 | 2013-12-04 21:11:03 +0100 | [diff] [blame] | 187 | The module :mod:`socket` exports the following elements. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 188 | |
| 189 | |
Antoine Pitrou | a5cc9d6 | 2013-12-04 21:11:03 +0100 | [diff] [blame] | 190 | Exceptions |
| 191 | ^^^^^^^^^^ |
| 192 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 193 | .. exception:: error |
| 194 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 195 | A deprecated alias of :exc:`OSError`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 196 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 197 | .. versionchanged:: 3.3 |
| 198 | Following :pep:`3151`, this class was made an alias of :exc:`OSError`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 199 | |
| 200 | |
| 201 | .. exception:: herror |
| 202 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 203 | A subclass of :exc:`OSError`, this exception is raised for |
Antoine Pitrou | f06576d | 2011-02-28 22:38:07 +0000 | [diff] [blame] | 204 | address-related errors, i.e. for functions that use *h_errno* in the POSIX |
| 205 | C API, including :func:`gethostbyname_ex` and :func:`gethostbyaddr`. |
| 206 | The accompanying value is a pair ``(h_errno, string)`` representing an |
| 207 | error returned by a library call. *h_errno* is a numeric value, while |
| 208 | *string* represents the description of *h_errno*, as returned by the |
| 209 | :c:func:`hstrerror` C function. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 210 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 211 | .. versionchanged:: 3.3 |
| 212 | This class was made a subclass of :exc:`OSError`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 213 | |
| 214 | .. exception:: gaierror |
| 215 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 216 | A subclass of :exc:`OSError`, this exception is raised for |
Antoine Pitrou | f06576d | 2011-02-28 22:38:07 +0000 | [diff] [blame] | 217 | address-related errors by :func:`getaddrinfo` and :func:`getnameinfo`. |
| 218 | The accompanying value is a pair ``(error, string)`` representing an error |
| 219 | returned by a library call. *string* represents the description of |
| 220 | *error*, as returned by the :c:func:`gai_strerror` C function. The |
| 221 | numeric *error* value will match one of the :const:`EAI_\*` constants |
| 222 | defined in this module. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 223 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 224 | .. versionchanged:: 3.3 |
| 225 | This class was made a subclass of :exc:`OSError`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 226 | |
| 227 | .. exception:: timeout |
| 228 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 229 | A subclass of :exc:`OSError`, this exception is raised when a timeout |
Antoine Pitrou | f06576d | 2011-02-28 22:38:07 +0000 | [diff] [blame] | 230 | occurs on a socket which has had timeouts enabled via a prior call to |
| 231 | :meth:`~socket.settimeout` (or implicitly through |
| 232 | :func:`~socket.setdefaulttimeout`). The accompanying value is a string |
| 233 | whose value is currently always "timed out". |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 234 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 235 | .. versionchanged:: 3.3 |
| 236 | This class was made a subclass of :exc:`OSError`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 237 | |
Antoine Pitrou | a5cc9d6 | 2013-12-04 21:11:03 +0100 | [diff] [blame] | 238 | |
| 239 | Constants |
| 240 | ^^^^^^^^^ |
| 241 | |
Ethan Furman | 7184bac | 2014-10-14 18:56:53 -0700 | [diff] [blame] | 242 | The AF_* and SOCK_* constants are now :class:`AddressFamily` and |
| 243 | :class:`SocketKind` :class:`.IntEnum` collections. |
| 244 | |
| 245 | .. versionadded:: 3.4 |
| 246 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 247 | .. data:: AF_UNIX |
| 248 | AF_INET |
| 249 | AF_INET6 |
| 250 | |
| 251 | These constants represent the address (and protocol) families, used for the |
Ezio Melotti | c048d98 | 2013-04-17 04:10:26 +0300 | [diff] [blame] | 252 | first argument to :func:`.socket`. If the :const:`AF_UNIX` constant is not |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 253 | defined then this protocol is unsupported. More constants may be available |
| 254 | depending on the system. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 255 | |
| 256 | |
| 257 | .. data:: SOCK_STREAM |
| 258 | SOCK_DGRAM |
| 259 | SOCK_RAW |
| 260 | SOCK_RDM |
| 261 | SOCK_SEQPACKET |
| 262 | |
| 263 | These constants represent the socket types, used for the second argument to |
Ezio Melotti | c048d98 | 2013-04-17 04:10:26 +0300 | [diff] [blame] | 264 | :func:`.socket`. More constants may be available depending on the system. |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 265 | (Only :const:`SOCK_STREAM` and :const:`SOCK_DGRAM` appear to be generally |
| 266 | useful.) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 267 | |
Antoine Pitrou | b1c5496 | 2010-10-14 15:05:38 +0000 | [diff] [blame] | 268 | .. data:: SOCK_CLOEXEC |
| 269 | SOCK_NONBLOCK |
| 270 | |
| 271 | These two constants, if defined, can be combined with the socket types and |
| 272 | allow you to set some flags atomically (thus avoiding possible race |
| 273 | conditions and the need for separate calls). |
| 274 | |
| 275 | .. seealso:: |
| 276 | |
| 277 | `Secure File Descriptor Handling <http://udrepper.livejournal.com/20407.html>`_ |
| 278 | for a more thorough explanation. |
| 279 | |
| 280 | Availability: Linux >= 2.6.27. |
| 281 | |
| 282 | .. versionadded:: 3.2 |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 283 | |
| 284 | .. data:: SO_* |
| 285 | SOMAXCONN |
| 286 | MSG_* |
| 287 | SOL_* |
Nick Coghlan | 96fe56a | 2011-08-22 11:55:57 +1000 | [diff] [blame] | 288 | SCM_* |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 289 | IPPROTO_* |
| 290 | IPPORT_* |
| 291 | INADDR_* |
| 292 | IP_* |
| 293 | IPV6_* |
| 294 | EAI_* |
| 295 | AI_* |
| 296 | NI_* |
| 297 | TCP_* |
| 298 | |
| 299 | Many constants of these forms, documented in the Unix documentation on sockets |
| 300 | and/or the IP protocol, are also defined in the socket module. They are |
| 301 | generally used in arguments to the :meth:`setsockopt` and :meth:`getsockopt` |
| 302 | methods of socket objects. In most cases, only those symbols that are defined |
| 303 | in the Unix header files are defined; for a few symbols, default values are |
| 304 | provided. |
| 305 | |
R David Murray | bdfa0eb | 2016-08-23 21:12:40 -0400 | [diff] [blame] | 306 | .. versionchanged:: 3.6 |
Victor Stinner | 01f5ae7 | 2017-01-23 12:30:00 +0100 | [diff] [blame] | 307 | ``SO_DOMAIN``, ``SO_PROTOCOL``, ``SO_PEERSEC``, ``SO_PASSSEC``, |
| 308 | ``TCP_USER_TIMEOUT``, ``TCP_CONGESTION`` were added. |
R David Murray | bdfa0eb | 2016-08-23 21:12:40 -0400 | [diff] [blame] | 309 | |
Nathaniel J. Smith | 1e2147b | 2017-03-22 20:56:55 -0700 | [diff] [blame] | 310 | .. versionchanged:: 3.7 |
| 311 | ``TCP_NOTSENT_LOWAT`` was added. |
| 312 | |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 313 | .. data:: AF_CAN |
| 314 | PF_CAN |
| 315 | SOL_CAN_* |
| 316 | CAN_* |
| 317 | |
| 318 | Many constants of these forms, documented in the Linux documentation, are |
| 319 | also defined in the socket module. |
| 320 | |
| 321 | Availability: Linux >= 2.6.25. |
| 322 | |
| 323 | .. versionadded:: 3.3 |
| 324 | |
Charles-François Natali | 773e42d | 2013-02-05 19:42:01 +0100 | [diff] [blame] | 325 | .. data:: CAN_BCM |
| 326 | CAN_BCM_* |
| 327 | |
| 328 | CAN_BCM, in the CAN protocol family, is the broadcast manager (BCM) protocol. |
| 329 | Broadcast manager constants, documented in the Linux documentation, are also |
| 330 | defined in the socket module. |
| 331 | |
| 332 | Availability: Linux >= 2.6.25. |
| 333 | |
| 334 | .. versionadded:: 3.4 |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 335 | |
Larry Hastings | a6cc551 | 2015-04-13 17:48:40 -0400 | [diff] [blame] | 336 | .. data:: CAN_RAW_FD_FRAMES |
| 337 | |
| 338 | Enables CAN FD support in a CAN_RAW socket. This is disabled by default. |
| 339 | This allows your application to send both CAN and CAN FD frames; however, |
| 340 | you one must accept both CAN and CAN FD frames when reading from the socket. |
| 341 | |
| 342 | This constant is documented in the Linux documentation. |
| 343 | |
| 344 | Availability: Linux >= 3.6. |
| 345 | |
| 346 | .. versionadded:: 3.5 |
| 347 | |
Pier-Yves Lessard | a30f6d4 | 2017-08-28 04:32:44 -0400 | [diff] [blame] | 348 | .. data:: CAN_ISOTP |
| 349 | |
| 350 | CAN_ISOTP, in the CAN protocol family, is the ISO-TP (ISO 15765-2) protocol. |
| 351 | ISO-TP constants, documented in the Linux documentation. |
| 352 | |
| 353 | Availability: Linux >= 2.6.25 |
| 354 | |
| 355 | .. versionadded:: 3.7 |
| 356 | |
| 357 | |
Charles-François Natali | 10b8cf4 | 2011-11-10 19:21:37 +0100 | [diff] [blame] | 358 | .. data:: AF_RDS |
| 359 | PF_RDS |
| 360 | SOL_RDS |
| 361 | RDS_* |
| 362 | |
| 363 | Many constants of these forms, documented in the Linux documentation, are |
| 364 | also defined in the socket module. |
| 365 | |
| 366 | Availability: Linux >= 2.6.30. |
| 367 | |
| 368 | .. versionadded:: 3.3 |
| 369 | |
| 370 | |
Steve Dower | ea93ac0 | 2016-06-17 12:52:18 -0700 | [diff] [blame] | 371 | .. data:: SIO_RCVALL |
| 372 | SIO_KEEPALIVE_VALS |
| 373 | SIO_LOOPBACK_FAST_PATH |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 374 | RCVALL_* |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 375 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 376 | Constants for Windows' WSAIoctl(). The constants are used as arguments to the |
Serhiy Storchaka | bfdcd43 | 2013-10-13 23:09:14 +0300 | [diff] [blame] | 377 | :meth:`~socket.socket.ioctl` method of socket objects. |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 378 | |
Steve Dower | ea93ac0 | 2016-06-17 12:52:18 -0700 | [diff] [blame] | 379 | .. versionchanged:: 3.6 |
| 380 | ``SIO_LOOPBACK_FAST_PATH`` was added. |
| 381 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 382 | |
Christian Heimes | 043d6f6 | 2008-01-07 17:19:16 +0000 | [diff] [blame] | 383 | .. data:: TIPC_* |
| 384 | |
| 385 | TIPC related constants, matching the ones exported by the C socket API. See |
| 386 | the TIPC documentation for more information. |
| 387 | |
Christian Heimes | dffa394 | 2016-09-05 23:54:41 +0200 | [diff] [blame] | 388 | .. data:: AF_ALG |
| 389 | SOL_ALG |
| 390 | ALG_* |
| 391 | |
| 392 | Constants for Linux Kernel cryptography. |
| 393 | |
| 394 | Availability: Linux >= 2.6.38. |
| 395 | |
| 396 | .. versionadded:: 3.6 |
| 397 | |
Giampaolo Rodola' | 80e1c43 | 2013-05-21 21:02:04 +0200 | [diff] [blame] | 398 | .. data:: AF_LINK |
| 399 | |
| 400 | Availability: BSD, OSX. |
| 401 | |
| 402 | .. versionadded:: 3.4 |
Christian Heimes | 043d6f6 | 2008-01-07 17:19:16 +0000 | [diff] [blame] | 403 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 404 | .. data:: has_ipv6 |
| 405 | |
| 406 | This constant contains a boolean value which indicates if IPv6 is supported on |
| 407 | this platform. |
| 408 | |
Martin Panter | ea7266d | 2015-09-11 23:14:57 +0000 | [diff] [blame] | 409 | .. data:: BDADDR_ANY |
| 410 | BDADDR_LOCAL |
| 411 | |
| 412 | These are string constants containing Bluetooth addresses with special |
| 413 | meanings. For example, :const:`BDADDR_ANY` can be used to indicate |
| 414 | any address when specifying the binding socket with |
| 415 | :const:`BTPROTO_RFCOMM`. |
| 416 | |
| 417 | .. data:: HCI_FILTER |
| 418 | HCI_TIME_STAMP |
| 419 | HCI_DATA_DIR |
| 420 | |
| 421 | For use with :const:`BTPROTO_HCI`. :const:`HCI_FILTER` is not |
| 422 | available for NetBSD or DragonFlyBSD. :const:`HCI_TIME_STAMP` and |
| 423 | :const:`HCI_DATA_DIR` are not available for FreeBSD, NetBSD, or |
| 424 | DragonFlyBSD. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 425 | |
Antoine Pitrou | a5cc9d6 | 2013-12-04 21:11:03 +0100 | [diff] [blame] | 426 | Functions |
| 427 | ^^^^^^^^^ |
| 428 | |
| 429 | Creating sockets |
| 430 | '''''''''''''''' |
| 431 | |
| 432 | The following functions all create :ref:`socket objects <socket-objects>`. |
| 433 | |
| 434 | |
Antoine Pitrou | f9c5494 | 2013-12-04 21:15:24 +0100 | [diff] [blame] | 435 | .. function:: socket(family=AF_INET, type=SOCK_STREAM, proto=0, fileno=None) |
Antoine Pitrou | a5cc9d6 | 2013-12-04 21:11:03 +0100 | [diff] [blame] | 436 | |
| 437 | Create a new socket using the given address family, socket type and protocol |
| 438 | number. The address family should be :const:`AF_INET` (the default), |
| 439 | :const:`AF_INET6`, :const:`AF_UNIX`, :const:`AF_CAN` or :const:`AF_RDS`. The |
| 440 | socket type should be :const:`SOCK_STREAM` (the default), |
| 441 | :const:`SOCK_DGRAM`, :const:`SOCK_RAW` or perhaps one of the other ``SOCK_`` |
Antoine Pitrou | f9c5494 | 2013-12-04 21:15:24 +0100 | [diff] [blame] | 442 | constants. The protocol number is usually zero and may be omitted or in the |
| 443 | case where the address family is :const:`AF_CAN` the protocol should be one |
Pier-Yves Lessard | a30f6d4 | 2017-08-28 04:32:44 -0400 | [diff] [blame] | 444 | of :const:`CAN_RAW`, :const:`CAN_BCM` or :const:`CAN_ISOTP`. If *fileno* is specified, the other |
Berker Peksag | 24a6109 | 2015-10-08 06:34:01 +0300 | [diff] [blame] | 445 | arguments are ignored, causing the socket with the specified file descriptor |
| 446 | to return. Unlike :func:`socket.fromfd`, *fileno* will return the same |
| 447 | socket and not a duplicate. This may help close a detached socket using |
| 448 | :meth:`socket.close()`. |
Antoine Pitrou | f9c5494 | 2013-12-04 21:15:24 +0100 | [diff] [blame] | 449 | |
| 450 | The newly created socket is :ref:`non-inheritable <fd_inheritance>`. |
Antoine Pitrou | a5cc9d6 | 2013-12-04 21:11:03 +0100 | [diff] [blame] | 451 | |
| 452 | .. versionchanged:: 3.3 |
| 453 | The AF_CAN family was added. |
| 454 | The AF_RDS family was added. |
| 455 | |
Antoine Pitrou | f9c5494 | 2013-12-04 21:15:24 +0100 | [diff] [blame] | 456 | .. versionchanged:: 3.4 |
| 457 | The CAN_BCM protocol was added. |
| 458 | |
| 459 | .. versionchanged:: 3.4 |
| 460 | The returned socket is now non-inheritable. |
| 461 | |
Pier-Yves Lessard | a30f6d4 | 2017-08-28 04:32:44 -0400 | [diff] [blame] | 462 | .. versionchanged:: 3.7 |
| 463 | The CAN_ISOTP protocol was added. |
Antoine Pitrou | a5cc9d6 | 2013-12-04 21:11:03 +0100 | [diff] [blame] | 464 | |
| 465 | .. function:: socketpair([family[, type[, proto]]]) |
| 466 | |
| 467 | Build a pair of connected socket objects using the given address family, socket |
| 468 | type, and protocol number. Address family, socket type, and protocol number are |
| 469 | as for the :func:`.socket` function above. The default family is :const:`AF_UNIX` |
| 470 | if defined on the platform; otherwise, the default is :const:`AF_INET`. |
Antoine Pitrou | a5cc9d6 | 2013-12-04 21:11:03 +0100 | [diff] [blame] | 471 | |
Antoine Pitrou | f9c5494 | 2013-12-04 21:15:24 +0100 | [diff] [blame] | 472 | The newly created sockets are :ref:`non-inheritable <fd_inheritance>`. |
| 473 | |
Antoine Pitrou | a5cc9d6 | 2013-12-04 21:11:03 +0100 | [diff] [blame] | 474 | .. versionchanged:: 3.2 |
| 475 | The returned socket objects now support the whole socket API, rather |
| 476 | than a subset. |
| 477 | |
Antoine Pitrou | f9c5494 | 2013-12-04 21:15:24 +0100 | [diff] [blame] | 478 | .. versionchanged:: 3.4 |
| 479 | The returned sockets are now non-inheritable. |
| 480 | |
Charles-François Natali | 98c745a | 2014-10-14 21:22:44 +0100 | [diff] [blame] | 481 | .. versionchanged:: 3.5 |
| 482 | Windows support added. |
| 483 | |
Antoine Pitrou | a5cc9d6 | 2013-12-04 21:11:03 +0100 | [diff] [blame] | 484 | |
Gregory P. Smith | b406637 | 2010-01-03 03:28:29 +0000 | [diff] [blame] | 485 | .. function:: create_connection(address[, timeout[, source_address]]) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 486 | |
Antoine Pitrou | 889a510 | 2012-01-12 08:06:19 +0100 | [diff] [blame] | 487 | Connect to a TCP service listening on the Internet *address* (a 2-tuple |
| 488 | ``(host, port)``), and return the socket object. This is a higher-level |
| 489 | function than :meth:`socket.connect`: if *host* is a non-numeric hostname, |
| 490 | it will try to resolve it for both :data:`AF_INET` and :data:`AF_INET6`, |
| 491 | and then try to connect to all possible addresses in turn until a |
| 492 | connection succeeds. This makes it easy to write clients that are |
| 493 | compatible to both IPv4 and IPv6. |
| 494 | |
| 495 | Passing the optional *timeout* parameter will set the timeout on the |
| 496 | socket instance before attempting to connect. If no *timeout* is |
| 497 | supplied, the global default timeout setting returned by |
Georg Brandl | f78e02b | 2008-06-10 17:40:04 +0000 | [diff] [blame] | 498 | :func:`getdefaulttimeout` is used. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 499 | |
Gregory P. Smith | b406637 | 2010-01-03 03:28:29 +0000 | [diff] [blame] | 500 | If supplied, *source_address* must be a 2-tuple ``(host, port)`` for the |
| 501 | socket to bind to as its source address before connecting. If host or port |
| 502 | are '' or 0 respectively the OS default behavior will be used. |
| 503 | |
| 504 | .. versionchanged:: 3.2 |
| 505 | *source_address* was added. |
| 506 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 507 | |
Antoine Pitrou | f9c5494 | 2013-12-04 21:15:24 +0100 | [diff] [blame] | 508 | .. function:: fromfd(fd, family, type, proto=0) |
Antoine Pitrou | a5cc9d6 | 2013-12-04 21:11:03 +0100 | [diff] [blame] | 509 | |
| 510 | Duplicate the file descriptor *fd* (an integer as returned by a file object's |
| 511 | :meth:`fileno` method) and build a socket object from the result. Address |
| 512 | family, socket type and protocol number are as for the :func:`.socket` function |
| 513 | above. The file descriptor should refer to a socket, but this is not checked --- |
| 514 | subsequent operations on the object may fail if the file descriptor is invalid. |
| 515 | This function is rarely needed, but can be used to get or set socket options on |
| 516 | a socket passed to a program as standard input or output (such as a server |
| 517 | started by the Unix inet daemon). The socket is assumed to be in blocking mode. |
| 518 | |
Antoine Pitrou | f9c5494 | 2013-12-04 21:15:24 +0100 | [diff] [blame] | 519 | The newly created socket is :ref:`non-inheritable <fd_inheritance>`. |
| 520 | |
| 521 | .. versionchanged:: 3.4 |
| 522 | The returned socket is now non-inheritable. |
| 523 | |
Antoine Pitrou | a5cc9d6 | 2013-12-04 21:11:03 +0100 | [diff] [blame] | 524 | |
| 525 | .. function:: fromshare(data) |
| 526 | |
| 527 | Instantiate a socket from data obtained from the :meth:`socket.share` |
| 528 | method. The socket is assumed to be in blocking mode. |
| 529 | |
| 530 | Availability: Windows. |
| 531 | |
| 532 | .. versionadded:: 3.3 |
| 533 | |
| 534 | |
| 535 | .. data:: SocketType |
| 536 | |
| 537 | This is a Python type object that represents the socket object type. It is the |
| 538 | same as ``type(socket(...))``. |
| 539 | |
| 540 | |
| 541 | Other functions |
| 542 | ''''''''''''''' |
| 543 | |
| 544 | The :mod:`socket` module also offers various network-related services: |
| 545 | |
| 546 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 547 | .. function:: getaddrinfo(host, port, family=0, type=0, proto=0, flags=0) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 548 | |
Antoine Pitrou | 9103597 | 2010-05-31 17:04:40 +0000 | [diff] [blame] | 549 | Translate the *host*/*port* argument into a sequence of 5-tuples that contain |
| 550 | all the necessary arguments for creating a socket connected to that service. |
| 551 | *host* is a domain name, a string representation of an IPv4/v6 address |
| 552 | or ``None``. *port* is a string service name such as ``'http'``, a numeric |
| 553 | port number or ``None``. By passing ``None`` as the value of *host* |
| 554 | and *port*, you can pass ``NULL`` to the underlying C API. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 555 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 556 | The *family*, *type* and *proto* arguments can be optionally specified |
Antoine Pitrou | 9103597 | 2010-05-31 17:04:40 +0000 | [diff] [blame] | 557 | in order to narrow the list of addresses returned. Passing zero as a |
| 558 | value for each of these arguments selects the full range of results. |
| 559 | The *flags* argument can be one or several of the ``AI_*`` constants, |
| 560 | and will influence how results are computed and returned. |
| 561 | For example, :const:`AI_NUMERICHOST` will disable domain name resolution |
| 562 | and will raise an error if *host* is a domain name. |
| 563 | |
| 564 | The function returns a list of 5-tuples with the following structure: |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 565 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 566 | ``(family, type, proto, canonname, sockaddr)`` |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 567 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 568 | In these tuples, *family*, *type*, *proto* are all integers and are |
Ezio Melotti | c048d98 | 2013-04-17 04:10:26 +0300 | [diff] [blame] | 569 | meant to be passed to the :func:`.socket` function. *canonname* will be |
Antoine Pitrou | 9103597 | 2010-05-31 17:04:40 +0000 | [diff] [blame] | 570 | a string representing the canonical name of the *host* if |
| 571 | :const:`AI_CANONNAME` is part of the *flags* argument; else *canonname* |
| 572 | will be empty. *sockaddr* is a tuple describing a socket address, whose |
| 573 | format depends on the returned *family* (a ``(address, port)`` 2-tuple for |
| 574 | :const:`AF_INET`, a ``(address, port, flow info, scope id)`` 4-tuple for |
| 575 | :const:`AF_INET6`), and is meant to be passed to the :meth:`socket.connect` |
| 576 | method. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 577 | |
Antoine Pitrou | 9103597 | 2010-05-31 17:04:40 +0000 | [diff] [blame] | 578 | The following example fetches address information for a hypothetical TCP |
Ned Deily | 11cf4f6 | 2015-06-01 21:19:30 -0700 | [diff] [blame] | 579 | connection to ``example.org`` on port 80 (results may differ on your |
Antoine Pitrou | 9103597 | 2010-05-31 17:04:40 +0000 | [diff] [blame] | 580 | system if IPv6 isn't enabled):: |
| 581 | |
Ned Deily | 11cf4f6 | 2015-06-01 21:19:30 -0700 | [diff] [blame] | 582 | >>> socket.getaddrinfo("example.org", 80, proto=socket.IPPROTO_TCP) |
Ned Deily | 1b79e2d | 2015-06-01 18:52:48 -0700 | [diff] [blame] | 583 | [(<AddressFamily.AF_INET6: 10>, <SocketType.SOCK_STREAM: 1>, |
Ned Deily | 11cf4f6 | 2015-06-01 21:19:30 -0700 | [diff] [blame] | 584 | 6, '', ('2606:2800:220:1:248:1893:25c8:1946', 80, 0, 0)), |
Ned Deily | 1b79e2d | 2015-06-01 18:52:48 -0700 | [diff] [blame] | 585 | (<AddressFamily.AF_INET: 2>, <SocketType.SOCK_STREAM: 1>, |
Ned Deily | 11cf4f6 | 2015-06-01 21:19:30 -0700 | [diff] [blame] | 586 | 6, '', ('93.184.216.34', 80))] |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 587 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 588 | .. versionchanged:: 3.2 |
Andrew Kuchling | 46ff4ee | 2014-02-15 16:39:37 -0500 | [diff] [blame] | 589 | parameters can now be passed using keyword arguments. |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 590 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 591 | .. function:: getfqdn([name]) |
| 592 | |
| 593 | Return a fully qualified domain name for *name*. If *name* is omitted or empty, |
| 594 | it is interpreted as the local host. To find the fully qualified name, the |
Benjamin Peterson | e9bbc8b | 2008-09-28 02:06:32 +0000 | [diff] [blame] | 595 | hostname returned by :func:`gethostbyaddr` is checked, followed by aliases for the |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 596 | host, if available. The first name which includes a period is selected. In |
| 597 | case no fully qualified domain name is available, the hostname as returned by |
| 598 | :func:`gethostname` is returned. |
| 599 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 600 | |
| 601 | .. function:: gethostbyname(hostname) |
| 602 | |
| 603 | Translate a host name to IPv4 address format. The IPv4 address is returned as a |
| 604 | string, such as ``'100.50.200.5'``. If the host name is an IPv4 address itself |
| 605 | it is returned unchanged. See :func:`gethostbyname_ex` for a more complete |
| 606 | interface. :func:`gethostbyname` does not support IPv6 name resolution, and |
| 607 | :func:`getaddrinfo` should be used instead for IPv4/v6 dual stack support. |
| 608 | |
| 609 | |
| 610 | .. function:: gethostbyname_ex(hostname) |
| 611 | |
| 612 | Translate a host name to IPv4 address format, extended interface. Return a |
| 613 | triple ``(hostname, aliaslist, ipaddrlist)`` where *hostname* is the primary |
| 614 | host name responding to the given *ip_address*, *aliaslist* is a (possibly |
| 615 | empty) list of alternative host names for the same address, and *ipaddrlist* is |
| 616 | a list of IPv4 addresses for the same interface on the same host (often but not |
| 617 | always a single address). :func:`gethostbyname_ex` does not support IPv6 name |
| 618 | resolution, and :func:`getaddrinfo` should be used instead for IPv4/v6 dual |
| 619 | stack support. |
| 620 | |
| 621 | |
| 622 | .. function:: gethostname() |
| 623 | |
| 624 | Return a string containing the hostname of the machine where the Python |
Benjamin Peterson | 65676e4 | 2008-11-05 21:42:45 +0000 | [diff] [blame] | 625 | interpreter is currently executing. |
| 626 | |
Benjamin Peterson | 65676e4 | 2008-11-05 21:42:45 +0000 | [diff] [blame] | 627 | Note: :func:`gethostname` doesn't always return the fully qualified domain |
Berker Peksag | 2a8baed | 2015-05-19 01:31:00 +0300 | [diff] [blame] | 628 | name; use :func:`getfqdn` for that. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 629 | |
| 630 | |
| 631 | .. function:: gethostbyaddr(ip_address) |
| 632 | |
| 633 | Return a triple ``(hostname, aliaslist, ipaddrlist)`` where *hostname* is the |
| 634 | primary host name responding to the given *ip_address*, *aliaslist* is a |
| 635 | (possibly empty) list of alternative host names for the same address, and |
| 636 | *ipaddrlist* is a list of IPv4/v6 addresses for the same interface on the same |
| 637 | host (most likely containing only a single address). To find the fully qualified |
| 638 | domain name, use the function :func:`getfqdn`. :func:`gethostbyaddr` supports |
| 639 | both IPv4 and IPv6. |
| 640 | |
| 641 | |
| 642 | .. function:: getnameinfo(sockaddr, flags) |
| 643 | |
| 644 | Translate a socket address *sockaddr* into a 2-tuple ``(host, port)``. Depending |
| 645 | on the settings of *flags*, the result can contain a fully-qualified domain name |
| 646 | or numeric address representation in *host*. Similarly, *port* can contain a |
| 647 | string port name or a numeric port number. |
| 648 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 649 | |
| 650 | .. function:: getprotobyname(protocolname) |
| 651 | |
| 652 | Translate an Internet protocol name (for example, ``'icmp'``) to a constant |
Ezio Melotti | c048d98 | 2013-04-17 04:10:26 +0300 | [diff] [blame] | 653 | suitable for passing as the (optional) third argument to the :func:`.socket` |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 654 | function. This is usually only needed for sockets opened in "raw" mode |
| 655 | (:const:`SOCK_RAW`); for the normal socket modes, the correct protocol is chosen |
| 656 | automatically if the protocol is omitted or zero. |
| 657 | |
| 658 | |
| 659 | .. function:: getservbyname(servicename[, protocolname]) |
| 660 | |
| 661 | Translate an Internet service name and protocol name to a port number for that |
| 662 | service. The optional protocol name, if given, should be ``'tcp'`` or |
| 663 | ``'udp'``, otherwise any protocol will match. |
| 664 | |
| 665 | |
| 666 | .. function:: getservbyport(port[, protocolname]) |
| 667 | |
| 668 | Translate an Internet port number and protocol name to a service name for that |
| 669 | service. The optional protocol name, if given, should be ``'tcp'`` or |
| 670 | ``'udp'``, otherwise any protocol will match. |
| 671 | |
| 672 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 673 | .. function:: ntohl(x) |
| 674 | |
| 675 | Convert 32-bit positive integers from network to host byte order. On machines |
| 676 | where the host byte order is the same as network byte order, this is a no-op; |
| 677 | otherwise, it performs a 4-byte swap operation. |
| 678 | |
| 679 | |
| 680 | .. function:: ntohs(x) |
| 681 | |
| 682 | Convert 16-bit positive integers from network to host byte order. On machines |
| 683 | where the host byte order is the same as network byte order, this is a no-op; |
| 684 | otherwise, it performs a 2-byte swap operation. |
| 685 | |
Serhiy Storchaka | 6a7d348 | 2016-10-02 12:34:40 +0300 | [diff] [blame] | 686 | .. deprecated:: 3.7 |
| 687 | In case *x* does not fit in 16-bit unsigned integer, but does fit in a |
| 688 | positive C int, it is silently truncated to 16-bit unsigned integer. |
| 689 | This silent truncation feature is deprecated, and will raise an |
| 690 | exception in future versions of Python. |
| 691 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 692 | |
| 693 | .. function:: htonl(x) |
| 694 | |
| 695 | Convert 32-bit positive integers from host to network byte order. On machines |
| 696 | where the host byte order is the same as network byte order, this is a no-op; |
| 697 | otherwise, it performs a 4-byte swap operation. |
| 698 | |
| 699 | |
| 700 | .. function:: htons(x) |
| 701 | |
| 702 | Convert 16-bit positive integers from host to network byte order. On machines |
| 703 | where the host byte order is the same as network byte order, this is a no-op; |
| 704 | otherwise, it performs a 2-byte swap operation. |
| 705 | |
Serhiy Storchaka | 6a7d348 | 2016-10-02 12:34:40 +0300 | [diff] [blame] | 706 | .. deprecated:: 3.7 |
| 707 | In case *x* does not fit in 16-bit unsigned integer, but does fit in a |
| 708 | positive C int, it is silently truncated to 16-bit unsigned integer. |
| 709 | This silent truncation feature is deprecated, and will raise an |
| 710 | exception in future versions of Python. |
| 711 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 712 | |
| 713 | .. function:: inet_aton(ip_string) |
| 714 | |
| 715 | Convert an IPv4 address from dotted-quad string format (for example, |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 716 | '123.45.67.89') to 32-bit packed binary format, as a bytes object four characters in |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 717 | length. This is useful when conversing with a program that uses the standard C |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 718 | library and needs objects of type :c:type:`struct in_addr`, which is the C type |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 719 | for the 32-bit packed binary this function returns. |
| 720 | |
Georg Brandl | f5123ef | 2009-06-04 10:28:36 +0000 | [diff] [blame] | 721 | :func:`inet_aton` also accepts strings with less than three dots; see the |
| 722 | Unix manual page :manpage:`inet(3)` for details. |
| 723 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 724 | If the IPv4 address string passed to this function is invalid, |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 725 | :exc:`OSError` will be raised. Note that exactly what is valid depends on |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 726 | the underlying C implementation of :c:func:`inet_aton`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 727 | |
Georg Brandl | 5f25972 | 2009-05-04 20:50:30 +0000 | [diff] [blame] | 728 | :func:`inet_aton` does not support IPv6, and :func:`inet_pton` should be used |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 729 | instead for IPv4/v6 dual stack support. |
| 730 | |
| 731 | |
| 732 | .. function:: inet_ntoa(packed_ip) |
| 733 | |
Serhiy Storchaka | 8490f5a | 2015-03-20 09:00:36 +0200 | [diff] [blame] | 734 | Convert a 32-bit packed IPv4 address (a :term:`bytes-like object` four |
| 735 | bytes in length) to its standard dotted-quad string representation (for example, |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 736 | '123.45.67.89'). This is useful when conversing with a program that uses the |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 737 | standard C library and needs objects of type :c:type:`struct in_addr`, which |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 738 | is the C type for the 32-bit packed binary data this function takes as an |
| 739 | argument. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 740 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 741 | If the byte sequence passed to this function is not exactly 4 bytes in |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 742 | length, :exc:`OSError` will be raised. :func:`inet_ntoa` does not |
Georg Brandl | 5f25972 | 2009-05-04 20:50:30 +0000 | [diff] [blame] | 743 | support IPv6, and :func:`inet_ntop` should be used instead for IPv4/v6 dual |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 744 | stack support. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 745 | |
Georg Brandl | 8c16cb9 | 2016-02-25 20:17:45 +0100 | [diff] [blame] | 746 | .. versionchanged:: 3.5 |
Serhiy Storchaka | 8490f5a | 2015-03-20 09:00:36 +0200 | [diff] [blame] | 747 | Writable :term:`bytes-like object` is now accepted. |
| 748 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 749 | |
| 750 | .. function:: inet_pton(address_family, ip_string) |
| 751 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 752 | Convert an IP address from its family-specific string format to a packed, |
| 753 | binary format. :func:`inet_pton` is useful when a library or network protocol |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 754 | calls for an object of type :c:type:`struct in_addr` (similar to |
| 755 | :func:`inet_aton`) or :c:type:`struct in6_addr`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 756 | |
| 757 | Supported values for *address_family* are currently :const:`AF_INET` and |
| 758 | :const:`AF_INET6`. If the IP address string *ip_string* is invalid, |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 759 | :exc:`OSError` will be raised. Note that exactly what is valid depends on |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 760 | both the value of *address_family* and the underlying implementation of |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 761 | :c:func:`inet_pton`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 762 | |
Atsuo Ishimoto | da0fc14 | 2012-07-16 15:16:54 +0900 | [diff] [blame] | 763 | Availability: Unix (maybe not all platforms), Windows. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 764 | |
R David Murray | 6c50101 | 2014-03-07 21:22:39 -0500 | [diff] [blame] | 765 | .. versionchanged:: 3.4 |
| 766 | Windows support added |
| 767 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 768 | |
| 769 | .. function:: inet_ntop(address_family, packed_ip) |
| 770 | |
Serhiy Storchaka | 8490f5a | 2015-03-20 09:00:36 +0200 | [diff] [blame] | 771 | Convert a packed IP address (a :term:`bytes-like object` of some number of |
| 772 | bytes) to its standard, family-specific string representation (for |
| 773 | example, ``'7.10.0.5'`` or ``'5aef:2b::8'``). |
| 774 | :func:`inet_ntop` is useful when a library or network protocol returns an |
| 775 | object of type :c:type:`struct in_addr` (similar to :func:`inet_ntoa`) or |
| 776 | :c:type:`struct in6_addr`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 777 | |
| 778 | Supported values for *address_family* are currently :const:`AF_INET` and |
Serhiy Storchaka | 8490f5a | 2015-03-20 09:00:36 +0200 | [diff] [blame] | 779 | :const:`AF_INET6`. If the bytes object *packed_ip* is not the correct |
| 780 | length for the specified address family, :exc:`ValueError` will be raised. |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 781 | :exc:`OSError` is raised for errors from the call to :func:`inet_ntop`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 782 | |
Atsuo Ishimoto | da0fc14 | 2012-07-16 15:16:54 +0900 | [diff] [blame] | 783 | Availability: Unix (maybe not all platforms), Windows. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 784 | |
R David Murray | 6c50101 | 2014-03-07 21:22:39 -0500 | [diff] [blame] | 785 | .. versionchanged:: 3.4 |
| 786 | Windows support added |
| 787 | |
Georg Brandl | 8c16cb9 | 2016-02-25 20:17:45 +0100 | [diff] [blame] | 788 | .. versionchanged:: 3.5 |
Serhiy Storchaka | 8490f5a | 2015-03-20 09:00:36 +0200 | [diff] [blame] | 789 | Writable :term:`bytes-like object` is now accepted. |
| 790 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 791 | |
Nick Coghlan | 96fe56a | 2011-08-22 11:55:57 +1000 | [diff] [blame] | 792 | .. |
| 793 | XXX: Are sendmsg(), recvmsg() and CMSG_*() available on any |
| 794 | non-Unix platforms? The old (obsolete?) 4.2BSD form of the |
| 795 | interface, in which struct msghdr has no msg_control or |
| 796 | msg_controllen members, is not currently supported. |
| 797 | |
| 798 | .. function:: CMSG_LEN(length) |
| 799 | |
| 800 | Return the total length, without trailing padding, of an ancillary |
| 801 | data item with associated data of the given *length*. This value |
| 802 | can often be used as the buffer size for :meth:`~socket.recvmsg` to |
| 803 | receive a single item of ancillary data, but :rfc:`3542` requires |
| 804 | portable applications to use :func:`CMSG_SPACE` and thus include |
| 805 | space for padding, even when the item will be the last in the |
| 806 | buffer. Raises :exc:`OverflowError` if *length* is outside the |
| 807 | permissible range of values. |
| 808 | |
| 809 | Availability: most Unix platforms, possibly others. |
| 810 | |
| 811 | .. versionadded:: 3.3 |
| 812 | |
| 813 | |
| 814 | .. function:: CMSG_SPACE(length) |
| 815 | |
| 816 | Return the buffer size needed for :meth:`~socket.recvmsg` to |
| 817 | receive an ancillary data item with associated data of the given |
| 818 | *length*, along with any trailing padding. The buffer space needed |
| 819 | to receive multiple items is the sum of the :func:`CMSG_SPACE` |
| 820 | values for their associated data lengths. Raises |
| 821 | :exc:`OverflowError` if *length* is outside the permissible range |
| 822 | of values. |
| 823 | |
| 824 | Note that some systems might support ancillary data without |
| 825 | providing this function. Also note that setting the buffer size |
| 826 | using the results of this function may not precisely limit the |
| 827 | amount of ancillary data that can be received, since additional |
| 828 | data may be able to fit into the padding area. |
| 829 | |
| 830 | Availability: most Unix platforms, possibly others. |
| 831 | |
| 832 | .. versionadded:: 3.3 |
| 833 | |
| 834 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 835 | .. function:: getdefaulttimeout() |
| 836 | |
Ezio Melotti | 388c945 | 2011-08-14 08:28:57 +0300 | [diff] [blame] | 837 | Return the default timeout in seconds (float) for new socket objects. A value |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 838 | of ``None`` indicates that new socket objects have no timeout. When the socket |
| 839 | module is first imported, the default is ``None``. |
| 840 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 841 | |
| 842 | .. function:: setdefaulttimeout(timeout) |
| 843 | |
Ezio Melotti | 388c945 | 2011-08-14 08:28:57 +0300 | [diff] [blame] | 844 | Set the default timeout in seconds (float) for new socket objects. When |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 845 | the socket module is first imported, the default is ``None``. See |
| 846 | :meth:`~socket.settimeout` for possible values and their respective |
| 847 | meanings. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 848 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 849 | |
Antoine Pitrou | 061cfb5 | 2011-02-28 22:25:22 +0000 | [diff] [blame] | 850 | .. function:: sethostname(name) |
| 851 | |
Serhiy Storchaka | d65c949 | 2015-11-02 14:10:23 +0200 | [diff] [blame] | 852 | Set the machine's hostname to *name*. This will raise an |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 853 | :exc:`OSError` if you don't have enough rights. |
Antoine Pitrou | 061cfb5 | 2011-02-28 22:25:22 +0000 | [diff] [blame] | 854 | |
| 855 | Availability: Unix. |
| 856 | |
| 857 | .. versionadded:: 3.3 |
| 858 | |
| 859 | |
Gregory P. Smith | 5ed2e77 | 2011-05-15 00:26:45 -0700 | [diff] [blame] | 860 | .. function:: if_nameindex() |
| 861 | |
Gregory P. Smith | b6471db | 2011-05-22 22:47:55 -0700 | [diff] [blame] | 862 | Return a list of network interface information |
| 863 | (index int, name string) tuples. |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 864 | :exc:`OSError` if the system call fails. |
Gregory P. Smith | 5ed2e77 | 2011-05-15 00:26:45 -0700 | [diff] [blame] | 865 | |
| 866 | Availability: Unix. |
| 867 | |
| 868 | .. versionadded:: 3.3 |
| 869 | |
| 870 | |
| 871 | .. function:: if_nametoindex(if_name) |
| 872 | |
Gregory P. Smith | b6471db | 2011-05-22 22:47:55 -0700 | [diff] [blame] | 873 | Return a network interface index number corresponding to an |
| 874 | interface name. |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 875 | :exc:`OSError` if no interface with the given name exists. |
Gregory P. Smith | 5ed2e77 | 2011-05-15 00:26:45 -0700 | [diff] [blame] | 876 | |
| 877 | Availability: Unix. |
| 878 | |
| 879 | .. versionadded:: 3.3 |
| 880 | |
| 881 | |
| 882 | .. function:: if_indextoname(if_index) |
| 883 | |
Serhiy Storchaka | d65c949 | 2015-11-02 14:10:23 +0200 | [diff] [blame] | 884 | Return a network interface name corresponding to an |
Gregory P. Smith | b6471db | 2011-05-22 22:47:55 -0700 | [diff] [blame] | 885 | interface index number. |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 886 | :exc:`OSError` if no interface with the given index exists. |
Gregory P. Smith | 5ed2e77 | 2011-05-15 00:26:45 -0700 | [diff] [blame] | 887 | |
| 888 | Availability: Unix. |
| 889 | |
| 890 | .. versionadded:: 3.3 |
| 891 | |
| 892 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 893 | .. _socket-objects: |
| 894 | |
| 895 | Socket Objects |
| 896 | -------------- |
| 897 | |
Antoine Pitrou | e3658a7 | 2013-12-04 21:02:42 +0100 | [diff] [blame] | 898 | Socket objects have the following methods. Except for |
| 899 | :meth:`~socket.makefile`, these correspond to Unix system calls applicable |
| 900 | to sockets. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 901 | |
Martin Panter | e37fc18 | 2016-04-24 04:24:36 +0000 | [diff] [blame] | 902 | .. versionchanged:: 3.2 |
| 903 | Support for the :term:`context manager` protocol was added. Exiting the |
| 904 | context manager is equivalent to calling :meth:`~socket.close`. |
| 905 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 906 | |
| 907 | .. method:: socket.accept() |
| 908 | |
| 909 | Accept a connection. The socket must be bound to an address and listening for |
| 910 | connections. The return value is a pair ``(conn, address)`` where *conn* is a |
| 911 | *new* socket object usable to send and receive data on the connection, and |
| 912 | *address* is the address bound to the socket on the other end of the connection. |
| 913 | |
Victor Stinner | daf4555 | 2013-08-28 00:53:59 +0200 | [diff] [blame] | 914 | The newly created socket is :ref:`non-inheritable <fd_inheritance>`. |
| 915 | |
| 916 | .. versionchanged:: 3.4 |
| 917 | The socket is now non-inheritable. |
| 918 | |
Victor Stinner | 708d9ba | 2015-04-02 11:49:42 +0200 | [diff] [blame] | 919 | .. versionchanged:: 3.5 |
| 920 | If the system call is interrupted and the signal handler does not raise |
| 921 | an exception, the method now retries the system call instead of raising |
| 922 | an :exc:`InterruptedError` exception (see :pep:`475` for the rationale). |
| 923 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 924 | |
| 925 | .. method:: socket.bind(address) |
| 926 | |
| 927 | Bind the socket to *address*. The socket must not already be bound. (The format |
| 928 | of *address* depends on the address family --- see above.) |
| 929 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 930 | |
| 931 | .. method:: socket.close() |
| 932 | |
Antoine Pitrou | e3658a7 | 2013-12-04 21:02:42 +0100 | [diff] [blame] | 933 | Mark the socket closed. The underlying system resource (e.g. a file |
| 934 | descriptor) is also closed when all file objects from :meth:`makefile()` |
| 935 | are closed. Once that happens, all future operations on the socket |
| 936 | object will fail. The remote end will receive no more data (after |
| 937 | queued data is flushed). |
| 938 | |
| 939 | Sockets are automatically closed when they are garbage-collected, but |
| 940 | it is recommended to :meth:`close` them explicitly, or to use a |
| 941 | :keyword:`with` statement around them. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 942 | |
Martin Panter | 50ab1a3 | 2016-04-11 00:38:12 +0000 | [diff] [blame] | 943 | .. versionchanged:: 3.6 |
| 944 | :exc:`OSError` is now raised if an error occurs when the underlying |
| 945 | :c:func:`close` call is made. |
| 946 | |
Antoine Pitrou | 4a67a46 | 2011-01-02 22:06:53 +0000 | [diff] [blame] | 947 | .. note:: |
Éric Araujo | fa5e6e4 | 2014-03-12 19:51:00 -0400 | [diff] [blame] | 948 | |
Antoine Pitrou | 4a67a46 | 2011-01-02 22:06:53 +0000 | [diff] [blame] | 949 | :meth:`close()` releases the resource associated with a connection but |
| 950 | does not necessarily close the connection immediately. If you want |
| 951 | to close the connection in a timely fashion, call :meth:`shutdown()` |
| 952 | before :meth:`close()`. |
| 953 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 954 | |
| 955 | .. method:: socket.connect(address) |
| 956 | |
| 957 | Connect to a remote socket at *address*. (The format of *address* depends on the |
| 958 | address family --- see above.) |
| 959 | |
Victor Stinner | 81c41db | 2015-04-02 11:50:57 +0200 | [diff] [blame] | 960 | If the connection is interrupted by a signal, the method waits until the |
| 961 | connection completes, or raise a :exc:`socket.timeout` on timeout, if the |
| 962 | signal handler doesn't raise an exception and the socket is blocking or has |
| 963 | a timeout. For non-blocking sockets, the method raises an |
| 964 | :exc:`InterruptedError` exception if the connection is interrupted by a |
| 965 | signal (or the exception raised by the signal handler). |
| 966 | |
| 967 | .. versionchanged:: 3.5 |
| 968 | The method now waits until the connection completes instead of raising an |
| 969 | :exc:`InterruptedError` exception if the connection is interrupted by a |
| 970 | signal, the signal handler doesn't raise an exception and the socket is |
| 971 | blocking or has a timeout (see the :pep:`475` for the rationale). |
| 972 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 973 | |
| 974 | .. method:: socket.connect_ex(address) |
| 975 | |
| 976 | Like ``connect(address)``, but return an error indicator instead of raising an |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 977 | exception for errors returned by the C-level :c:func:`connect` call (other |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 978 | problems, such as "host not found," can still raise exceptions). The error |
| 979 | indicator is ``0`` if the operation succeeded, otherwise the value of the |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 980 | :c:data:`errno` variable. This is useful to support, for example, asynchronous |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 981 | connects. |
| 982 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 983 | |
Antoine Pitrou | 6e451df | 2010-08-09 20:39:54 +0000 | [diff] [blame] | 984 | .. method:: socket.detach() |
| 985 | |
| 986 | Put the socket object into closed state without actually closing the |
| 987 | underlying file descriptor. The file descriptor is returned, and can |
| 988 | be reused for other purposes. |
| 989 | |
| 990 | .. versionadded:: 3.2 |
| 991 | |
| 992 | |
Victor Stinner | daf4555 | 2013-08-28 00:53:59 +0200 | [diff] [blame] | 993 | .. method:: socket.dup() |
| 994 | |
| 995 | Duplicate the socket. |
| 996 | |
| 997 | The newly created socket is :ref:`non-inheritable <fd_inheritance>`. |
| 998 | |
| 999 | .. versionchanged:: 3.4 |
| 1000 | The socket is now non-inheritable. |
| 1001 | |
| 1002 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1003 | .. method:: socket.fileno() |
| 1004 | |
Kushal Das | 89beb27 | 2016-06-04 10:20:12 -0700 | [diff] [blame] | 1005 | Return the socket's file descriptor (a small integer), or -1 on failure. This |
| 1006 | is useful with :func:`select.select`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1007 | |
| 1008 | Under Windows the small integer returned by this method cannot be used where a |
| 1009 | file descriptor can be used (such as :func:`os.fdopen`). Unix does not have |
| 1010 | this limitation. |
| 1011 | |
Victor Stinner | daf4555 | 2013-08-28 00:53:59 +0200 | [diff] [blame] | 1012 | .. method:: socket.get_inheritable() |
| 1013 | |
| 1014 | Get the :ref:`inheritable flag <fd_inheritance>` of the socket's file |
| 1015 | descriptor or socket's handle: ``True`` if the socket can be inherited in |
| 1016 | child processes, ``False`` if it cannot. |
| 1017 | |
| 1018 | .. versionadded:: 3.4 |
| 1019 | |
| 1020 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1021 | .. method:: socket.getpeername() |
| 1022 | |
| 1023 | Return the remote address to which the socket is connected. This is useful to |
| 1024 | find out the port number of a remote IPv4/v6 socket, for instance. (The format |
| 1025 | of the address returned depends on the address family --- see above.) On some |
| 1026 | systems this function is not supported. |
| 1027 | |
| 1028 | |
| 1029 | .. method:: socket.getsockname() |
| 1030 | |
| 1031 | Return the socket's own address. This is useful to find out the port number of |
| 1032 | an IPv4/v6 socket, for instance. (The format of the address returned depends on |
| 1033 | the address family --- see above.) |
| 1034 | |
| 1035 | |
| 1036 | .. method:: socket.getsockopt(level, optname[, buflen]) |
| 1037 | |
| 1038 | Return the value of the given socket option (see the Unix man page |
| 1039 | :manpage:`getsockopt(2)`). The needed symbolic constants (:const:`SO_\*` etc.) |
| 1040 | are defined in this module. If *buflen* is absent, an integer option is assumed |
| 1041 | and its integer value is returned by the function. If *buflen* is present, it |
| 1042 | specifies the maximum length of the buffer used to receive the option in, and |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 1043 | this buffer is returned as a bytes object. It is up to the caller to decode the |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1044 | contents of the buffer (see the optional built-in module :mod:`struct` for a way |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 1045 | to decode C structures encoded as byte strings). |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1046 | |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1047 | |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 1048 | .. method:: socket.gettimeout() |
| 1049 | |
Ezio Melotti | 388c945 | 2011-08-14 08:28:57 +0300 | [diff] [blame] | 1050 | Return the timeout in seconds (float) associated with socket operations, |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 1051 | or ``None`` if no timeout is set. This reflects the last call to |
| 1052 | :meth:`setblocking` or :meth:`settimeout`. |
| 1053 | |
| 1054 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1055 | .. method:: socket.ioctl(control, option) |
| 1056 | |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1057 | :platform: Windows |
| 1058 | |
Christian Heimes | 679db4a | 2008-01-18 09:56:22 +0000 | [diff] [blame] | 1059 | The :meth:`ioctl` method is a limited interface to the WSAIoctl system |
Georg Brandl | 8569e58 | 2010-05-19 20:57:08 +0000 | [diff] [blame] | 1060 | interface. Please refer to the `Win32 documentation |
Georg Brandl | 5d94134 | 2016-02-26 19:37:12 +0100 | [diff] [blame] | 1061 | <https://msdn.microsoft.com/en-us/library/ms741621%28VS.85%29.aspx>`_ for more |
Georg Brandl | 8569e58 | 2010-05-19 20:57:08 +0000 | [diff] [blame] | 1062 | information. |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1063 | |
Alexandre Vassalotti | 6d3dfc3 | 2009-07-29 19:54:39 +0000 | [diff] [blame] | 1064 | On other platforms, the generic :func:`fcntl.fcntl` and :func:`fcntl.ioctl` |
| 1065 | functions may be used; they accept a socket object as their first argument. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1066 | |
Steve Dower | ea93ac0 | 2016-06-17 12:52:18 -0700 | [diff] [blame] | 1067 | Currently only the following control codes are supported: |
| 1068 | ``SIO_RCVALL``, ``SIO_KEEPALIVE_VALS``, and ``SIO_LOOPBACK_FAST_PATH``. |
| 1069 | |
| 1070 | .. versionchanged:: 3.6 |
| 1071 | ``SIO_LOOPBACK_FAST_PATH`` was added. |
| 1072 | |
Charles-François Natali | 644b8f5 | 2014-05-22 19:45:39 +0100 | [diff] [blame] | 1073 | .. method:: socket.listen([backlog]) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1074 | |
Charles-François Natali | 644b8f5 | 2014-05-22 19:45:39 +0100 | [diff] [blame] | 1075 | Enable a server to accept connections. If *backlog* is specified, it must |
| 1076 | be at least 0 (if it is lower, it is set to 0); it specifies the number of |
| 1077 | unaccepted connections that the system will allow before refusing new |
| 1078 | connections. If not specified, a default reasonable value is chosen. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1079 | |
Charles-François Natali | 644b8f5 | 2014-05-22 19:45:39 +0100 | [diff] [blame] | 1080 | .. versionchanged:: 3.5 |
| 1081 | The *backlog* parameter is now optional. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1082 | |
Georg Brandl | e9e8c9b | 2010-12-28 11:49:41 +0000 | [diff] [blame] | 1083 | .. method:: socket.makefile(mode='r', buffering=None, *, encoding=None, \ |
| 1084 | errors=None, newline=None) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1085 | |
| 1086 | .. index:: single: I/O control; buffering |
| 1087 | |
Georg Brandl | e9e8c9b | 2010-12-28 11:49:41 +0000 | [diff] [blame] | 1088 | Return a :term:`file object` associated with the socket. The exact returned |
| 1089 | type depends on the arguments given to :meth:`makefile`. These arguments are |
Berker Peksag | 3fe64d0 | 2016-02-18 17:34:00 +0200 | [diff] [blame] | 1090 | interpreted the same way as by the built-in :func:`open` function, except |
| 1091 | the only supported *mode* values are ``'r'`` (default), ``'w'`` and ``'b'``. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1092 | |
Antoine Pitrou | e3658a7 | 2013-12-04 21:02:42 +0100 | [diff] [blame] | 1093 | The socket must be in blocking mode; it can have a timeout, but the file |
Martin Panter | 7462b649 | 2015-11-02 03:37:02 +0000 | [diff] [blame] | 1094 | object's internal buffer may end up in an inconsistent state if a timeout |
Antoine Pitrou | e3658a7 | 2013-12-04 21:02:42 +0100 | [diff] [blame] | 1095 | occurs. |
| 1096 | |
| 1097 | Closing the file object returned by :meth:`makefile` won't close the |
| 1098 | original socket unless all other file objects have been closed and |
| 1099 | :meth:`socket.close` has been called on the socket object. |
Georg Brandl | e9e8c9b | 2010-12-28 11:49:41 +0000 | [diff] [blame] | 1100 | |
| 1101 | .. note:: |
| 1102 | |
| 1103 | On Windows, the file-like object created by :meth:`makefile` cannot be |
| 1104 | used where a file object with a file descriptor is expected, such as the |
| 1105 | stream arguments of :meth:`subprocess.Popen`. |
Antoine Pitrou | 4adb288 | 2010-01-04 18:50:53 +0000 | [diff] [blame] | 1106 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1107 | |
| 1108 | .. method:: socket.recv(bufsize[, flags]) |
| 1109 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 1110 | Receive data from the socket. The return value is a bytes object representing the |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1111 | data received. The maximum amount of data to be received at once is specified |
| 1112 | by *bufsize*. See the Unix manual page :manpage:`recv(2)` for the meaning of |
| 1113 | the optional argument *flags*; it defaults to zero. |
| 1114 | |
| 1115 | .. note:: |
| 1116 | |
| 1117 | For best match with hardware and network realities, the value of *bufsize* |
| 1118 | should be a relatively small power of 2, for example, 4096. |
| 1119 | |
Victor Stinner | 708d9ba | 2015-04-02 11:49:42 +0200 | [diff] [blame] | 1120 | .. versionchanged:: 3.5 |
| 1121 | If the system call is interrupted and the signal handler does not raise |
| 1122 | an exception, the method now retries the system call instead of raising |
| 1123 | an :exc:`InterruptedError` exception (see :pep:`475` for the rationale). |
| 1124 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1125 | |
| 1126 | .. method:: socket.recvfrom(bufsize[, flags]) |
| 1127 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 1128 | Receive data from the socket. The return value is a pair ``(bytes, address)`` |
| 1129 | where *bytes* is a bytes object representing the data received and *address* is the |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1130 | address of the socket sending the data. See the Unix manual page |
| 1131 | :manpage:`recv(2)` for the meaning of the optional argument *flags*; it defaults |
| 1132 | to zero. (The format of *address* depends on the address family --- see above.) |
| 1133 | |
Victor Stinner | 708d9ba | 2015-04-02 11:49:42 +0200 | [diff] [blame] | 1134 | .. versionchanged:: 3.5 |
| 1135 | If the system call is interrupted and the signal handler does not raise |
| 1136 | an exception, the method now retries the system call instead of raising |
| 1137 | an :exc:`InterruptedError` exception (see :pep:`475` for the rationale). |
| 1138 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1139 | |
Nick Coghlan | 96fe56a | 2011-08-22 11:55:57 +1000 | [diff] [blame] | 1140 | .. method:: socket.recvmsg(bufsize[, ancbufsize[, flags]]) |
| 1141 | |
| 1142 | Receive normal data (up to *bufsize* bytes) and ancillary data from |
| 1143 | the socket. The *ancbufsize* argument sets the size in bytes of |
| 1144 | the internal buffer used to receive the ancillary data; it defaults |
| 1145 | to 0, meaning that no ancillary data will be received. Appropriate |
| 1146 | buffer sizes for ancillary data can be calculated using |
| 1147 | :func:`CMSG_SPACE` or :func:`CMSG_LEN`, and items which do not fit |
| 1148 | into the buffer might be truncated or discarded. The *flags* |
| 1149 | argument defaults to 0 and has the same meaning as for |
| 1150 | :meth:`recv`. |
| 1151 | |
| 1152 | The return value is a 4-tuple: ``(data, ancdata, msg_flags, |
| 1153 | address)``. The *data* item is a :class:`bytes` object holding the |
| 1154 | non-ancillary data received. The *ancdata* item is a list of zero |
| 1155 | or more tuples ``(cmsg_level, cmsg_type, cmsg_data)`` representing |
| 1156 | the ancillary data (control messages) received: *cmsg_level* and |
| 1157 | *cmsg_type* are integers specifying the protocol level and |
| 1158 | protocol-specific type respectively, and *cmsg_data* is a |
| 1159 | :class:`bytes` object holding the associated data. The *msg_flags* |
| 1160 | item is the bitwise OR of various flags indicating conditions on |
| 1161 | the received message; see your system documentation for details. |
| 1162 | If the receiving socket is unconnected, *address* is the address of |
| 1163 | the sending socket, if available; otherwise, its value is |
| 1164 | unspecified. |
| 1165 | |
| 1166 | On some systems, :meth:`sendmsg` and :meth:`recvmsg` can be used to |
| 1167 | pass file descriptors between processes over an :const:`AF_UNIX` |
| 1168 | socket. When this facility is used (it is often restricted to |
| 1169 | :const:`SOCK_STREAM` sockets), :meth:`recvmsg` will return, in its |
| 1170 | ancillary data, items of the form ``(socket.SOL_SOCKET, |
| 1171 | socket.SCM_RIGHTS, fds)``, where *fds* is a :class:`bytes` object |
| 1172 | representing the new file descriptors as a binary array of the |
| 1173 | native C :c:type:`int` type. If :meth:`recvmsg` raises an |
| 1174 | exception after the system call returns, it will first attempt to |
| 1175 | close any file descriptors received via this mechanism. |
| 1176 | |
| 1177 | Some systems do not indicate the truncated length of ancillary data |
| 1178 | items which have been only partially received. If an item appears |
| 1179 | to extend beyond the end of the buffer, :meth:`recvmsg` will issue |
| 1180 | a :exc:`RuntimeWarning`, and will return the part of it which is |
| 1181 | inside the buffer provided it has not been truncated before the |
| 1182 | start of its associated data. |
| 1183 | |
| 1184 | On systems which support the :const:`SCM_RIGHTS` mechanism, the |
| 1185 | following function will receive up to *maxfds* file descriptors, |
| 1186 | returning the message data and a list containing the descriptors |
| 1187 | (while ignoring unexpected conditions such as unrelated control |
| 1188 | messages being received). See also :meth:`sendmsg`. :: |
| 1189 | |
| 1190 | import socket, array |
| 1191 | |
| 1192 | def recv_fds(sock, msglen, maxfds): |
| 1193 | fds = array.array("i") # Array of ints |
| 1194 | msg, ancdata, flags, addr = sock.recvmsg(msglen, socket.CMSG_LEN(maxfds * fds.itemsize)) |
| 1195 | for cmsg_level, cmsg_type, cmsg_data in ancdata: |
| 1196 | if (cmsg_level == socket.SOL_SOCKET and cmsg_type == socket.SCM_RIGHTS): |
| 1197 | # Append data, ignoring any truncated integers at the end. |
| 1198 | fds.fromstring(cmsg_data[:len(cmsg_data) - (len(cmsg_data) % fds.itemsize)]) |
| 1199 | return msg, list(fds) |
| 1200 | |
| 1201 | Availability: most Unix platforms, possibly others. |
| 1202 | |
| 1203 | .. versionadded:: 3.3 |
| 1204 | |
Victor Stinner | 708d9ba | 2015-04-02 11:49:42 +0200 | [diff] [blame] | 1205 | .. versionchanged:: 3.5 |
| 1206 | If the system call is interrupted and the signal handler does not raise |
| 1207 | an exception, the method now retries the system call instead of raising |
| 1208 | an :exc:`InterruptedError` exception (see :pep:`475` for the rationale). |
| 1209 | |
Nick Coghlan | 96fe56a | 2011-08-22 11:55:57 +1000 | [diff] [blame] | 1210 | |
| 1211 | .. method:: socket.recvmsg_into(buffers[, ancbufsize[, flags]]) |
| 1212 | |
| 1213 | Receive normal data and ancillary data from the socket, behaving as |
| 1214 | :meth:`recvmsg` would, but scatter the non-ancillary data into a |
| 1215 | series of buffers instead of returning a new bytes object. The |
| 1216 | *buffers* argument must be an iterable of objects that export |
| 1217 | writable buffers (e.g. :class:`bytearray` objects); these will be |
| 1218 | filled with successive chunks of the non-ancillary data until it |
| 1219 | has all been written or there are no more buffers. The operating |
| 1220 | system may set a limit (:func:`~os.sysconf` value ``SC_IOV_MAX``) |
| 1221 | on the number of buffers that can be used. The *ancbufsize* and |
| 1222 | *flags* arguments have the same meaning as for :meth:`recvmsg`. |
| 1223 | |
| 1224 | The return value is a 4-tuple: ``(nbytes, ancdata, msg_flags, |
| 1225 | address)``, where *nbytes* is the total number of bytes of |
| 1226 | non-ancillary data written into the buffers, and *ancdata*, |
| 1227 | *msg_flags* and *address* are the same as for :meth:`recvmsg`. |
| 1228 | |
| 1229 | Example:: |
| 1230 | |
| 1231 | >>> import socket |
| 1232 | >>> s1, s2 = socket.socketpair() |
| 1233 | >>> b1 = bytearray(b'----') |
| 1234 | >>> b2 = bytearray(b'0123456789') |
| 1235 | >>> b3 = bytearray(b'--------------') |
| 1236 | >>> s1.send(b'Mary had a little lamb') |
| 1237 | 22 |
| 1238 | >>> s2.recvmsg_into([b1, memoryview(b2)[2:9], b3]) |
| 1239 | (22, [], 0, None) |
| 1240 | >>> [b1, b2, b3] |
| 1241 | [bytearray(b'Mary'), bytearray(b'01 had a 9'), bytearray(b'little lamb---')] |
| 1242 | |
| 1243 | Availability: most Unix platforms, possibly others. |
| 1244 | |
| 1245 | .. versionadded:: 3.3 |
| 1246 | |
| 1247 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1248 | .. method:: socket.recvfrom_into(buffer[, nbytes[, flags]]) |
| 1249 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 1250 | Receive data from the socket, writing it into *buffer* instead of creating a |
| 1251 | new bytestring. The return value is a pair ``(nbytes, address)`` where *nbytes* is |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1252 | the number of bytes received and *address* is the address of the socket sending |
| 1253 | the data. See the Unix manual page :manpage:`recv(2)` for the meaning of the |
| 1254 | optional argument *flags*; it defaults to zero. (The format of *address* |
| 1255 | depends on the address family --- see above.) |
| 1256 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1257 | |
| 1258 | .. method:: socket.recv_into(buffer[, nbytes[, flags]]) |
| 1259 | |
| 1260 | Receive up to *nbytes* bytes from the socket, storing the data into a buffer |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 1261 | rather than creating a new bytestring. If *nbytes* is not specified (or 0), |
Benjamin Peterson | 08bf91c | 2010-04-11 16:12:57 +0000 | [diff] [blame] | 1262 | receive up to the size available in the given buffer. Returns the number of |
| 1263 | bytes received. See the Unix manual page :manpage:`recv(2)` for the meaning |
| 1264 | of the optional argument *flags*; it defaults to zero. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1265 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1266 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 1267 | .. method:: socket.send(bytes[, flags]) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1268 | |
| 1269 | Send data to the socket. The socket must be connected to a remote socket. The |
| 1270 | optional *flags* argument has the same meaning as for :meth:`recv` above. |
| 1271 | Returns the number of bytes sent. Applications are responsible for checking that |
| 1272 | all data has been sent; if only some of the data was transmitted, the |
Senthil Kumaran | 6e13f13 | 2012-02-09 17:54:17 +0800 | [diff] [blame] | 1273 | application needs to attempt delivery of the remaining data. For further |
| 1274 | information on this topic, consult the :ref:`socket-howto`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1275 | |
Victor Stinner | 708d9ba | 2015-04-02 11:49:42 +0200 | [diff] [blame] | 1276 | .. versionchanged:: 3.5 |
| 1277 | If the system call is interrupted and the signal handler does not raise |
| 1278 | an exception, the method now retries the system call instead of raising |
| 1279 | an :exc:`InterruptedError` exception (see :pep:`475` for the rationale). |
| 1280 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1281 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 1282 | .. method:: socket.sendall(bytes[, flags]) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1283 | |
| 1284 | Send data to the socket. The socket must be connected to a remote socket. The |
| 1285 | optional *flags* argument has the same meaning as for :meth:`recv` above. |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 1286 | Unlike :meth:`send`, this method continues to send data from *bytes* until |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1287 | either all data has been sent or an error occurs. ``None`` is returned on |
| 1288 | success. On error, an exception is raised, and there is no way to determine how |
| 1289 | much data, if any, was successfully sent. |
| 1290 | |
Victor Stinner | 708d9ba | 2015-04-02 11:49:42 +0200 | [diff] [blame] | 1291 | .. versionchanged:: 3.5 |
Martin Panter | eb99570 | 2016-07-28 01:11:04 +0000 | [diff] [blame] | 1292 | The socket timeout is no more reset each time data is sent successfully. |
Victor Stinner | 8912d14 | 2015-04-06 23:16:34 +0200 | [diff] [blame] | 1293 | The socket timeout is now the maximum total duration to send all data. |
| 1294 | |
| 1295 | .. versionchanged:: 3.5 |
Victor Stinner | 708d9ba | 2015-04-02 11:49:42 +0200 | [diff] [blame] | 1296 | If the system call is interrupted and the signal handler does not raise |
| 1297 | an exception, the method now retries the system call instead of raising |
| 1298 | an :exc:`InterruptedError` exception (see :pep:`475` for the rationale). |
| 1299 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1300 | |
Ezio Melotti | e0add76 | 2012-09-14 06:32:35 +0300 | [diff] [blame] | 1301 | .. method:: socket.sendto(bytes, address) |
| 1302 | socket.sendto(bytes, flags, address) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1303 | |
| 1304 | Send data to the socket. The socket should not be connected to a remote socket, |
| 1305 | since the destination socket is specified by *address*. The optional *flags* |
| 1306 | argument has the same meaning as for :meth:`recv` above. Return the number of |
| 1307 | bytes sent. (The format of *address* depends on the address family --- see |
| 1308 | above.) |
| 1309 | |
Victor Stinner | 708d9ba | 2015-04-02 11:49:42 +0200 | [diff] [blame] | 1310 | .. versionchanged:: 3.5 |
| 1311 | If the system call is interrupted and the signal handler does not raise |
| 1312 | an exception, the method now retries the system call instead of raising |
| 1313 | an :exc:`InterruptedError` exception (see :pep:`475` for the rationale). |
| 1314 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1315 | |
Nick Coghlan | 96fe56a | 2011-08-22 11:55:57 +1000 | [diff] [blame] | 1316 | .. method:: socket.sendmsg(buffers[, ancdata[, flags[, address]]]) |
| 1317 | |
| 1318 | Send normal and ancillary data to the socket, gathering the |
| 1319 | non-ancillary data from a series of buffers and concatenating it |
| 1320 | into a single message. The *buffers* argument specifies the |
Serhiy Storchaka | b757c83 | 2014-12-05 22:25:22 +0200 | [diff] [blame] | 1321 | non-ancillary data as an iterable of |
| 1322 | :term:`bytes-like objects <bytes-like object>` |
Nick Coghlan | 96fe56a | 2011-08-22 11:55:57 +1000 | [diff] [blame] | 1323 | (e.g. :class:`bytes` objects); the operating system may set a limit |
| 1324 | (:func:`~os.sysconf` value ``SC_IOV_MAX``) on the number of buffers |
| 1325 | that can be used. The *ancdata* argument specifies the ancillary |
| 1326 | data (control messages) as an iterable of zero or more tuples |
| 1327 | ``(cmsg_level, cmsg_type, cmsg_data)``, where *cmsg_level* and |
| 1328 | *cmsg_type* are integers specifying the protocol level and |
| 1329 | protocol-specific type respectively, and *cmsg_data* is a |
Serhiy Storchaka | b757c83 | 2014-12-05 22:25:22 +0200 | [diff] [blame] | 1330 | bytes-like object holding the associated data. Note that |
Nick Coghlan | 96fe56a | 2011-08-22 11:55:57 +1000 | [diff] [blame] | 1331 | some systems (in particular, systems without :func:`CMSG_SPACE`) |
| 1332 | might support sending only one control message per call. The |
| 1333 | *flags* argument defaults to 0 and has the same meaning as for |
| 1334 | :meth:`send`. If *address* is supplied and not ``None``, it sets a |
| 1335 | destination address for the message. The return value is the |
| 1336 | number of bytes of non-ancillary data sent. |
| 1337 | |
| 1338 | The following function sends the list of file descriptors *fds* |
| 1339 | over an :const:`AF_UNIX` socket, on systems which support the |
| 1340 | :const:`SCM_RIGHTS` mechanism. See also :meth:`recvmsg`. :: |
| 1341 | |
| 1342 | import socket, array |
| 1343 | |
| 1344 | def send_fds(sock, msg, fds): |
| 1345 | return sock.sendmsg([msg], [(socket.SOL_SOCKET, socket.SCM_RIGHTS, array.array("i", fds))]) |
| 1346 | |
| 1347 | Availability: most Unix platforms, possibly others. |
| 1348 | |
| 1349 | .. versionadded:: 3.3 |
| 1350 | |
Victor Stinner | 708d9ba | 2015-04-02 11:49:42 +0200 | [diff] [blame] | 1351 | .. versionchanged:: 3.5 |
| 1352 | If the system call is interrupted and the signal handler does not raise |
| 1353 | an exception, the method now retries the system call instead of raising |
| 1354 | an :exc:`InterruptedError` exception (see :pep:`475` for the rationale). |
| 1355 | |
Christian Heimes | dffa394 | 2016-09-05 23:54:41 +0200 | [diff] [blame] | 1356 | .. method:: socket.sendmsg_afalg([msg], *, op[, iv[, assoclen[, flags]]]) |
| 1357 | |
| 1358 | Specialized version of :meth:`~socket.sendmsg` for :const:`AF_ALG` socket. |
| 1359 | Set mode, IV, AEAD associated data length and flags for :const:`AF_ALG` socket. |
| 1360 | |
| 1361 | Availability: Linux >= 2.6.38 |
| 1362 | |
| 1363 | .. versionadded:: 3.6 |
| 1364 | |
Giampaolo Rodola' | 915d141 | 2014-06-11 03:54:30 +0200 | [diff] [blame] | 1365 | .. method:: socket.sendfile(file, offset=0, count=None) |
| 1366 | |
| 1367 | Send a file until EOF is reached by using high-performance |
| 1368 | :mod:`os.sendfile` and return the total number of bytes which were sent. |
| 1369 | *file* must be a regular file object opened in binary mode. If |
| 1370 | :mod:`os.sendfile` is not available (e.g. Windows) or *file* is not a |
| 1371 | regular file :meth:`send` will be used instead. *offset* tells from where to |
| 1372 | start reading the file. If specified, *count* is the total number of bytes |
| 1373 | to transmit as opposed to sending the file until EOF is reached. File |
| 1374 | position is updated on return or also in case of error in which case |
| 1375 | :meth:`file.tell() <io.IOBase.tell>` can be used to figure out the number of |
Martin Panter | 8f13783 | 2017-01-14 08:24:20 +0000 | [diff] [blame] | 1376 | bytes which were sent. The socket must be of :const:`SOCK_STREAM` type. |
| 1377 | Non-blocking sockets are not supported. |
Giampaolo Rodola' | 915d141 | 2014-06-11 03:54:30 +0200 | [diff] [blame] | 1378 | |
| 1379 | .. versionadded:: 3.5 |
Nick Coghlan | 96fe56a | 2011-08-22 11:55:57 +1000 | [diff] [blame] | 1380 | |
Victor Stinner | daf4555 | 2013-08-28 00:53:59 +0200 | [diff] [blame] | 1381 | .. method:: socket.set_inheritable(inheritable) |
| 1382 | |
| 1383 | Set the :ref:`inheritable flag <fd_inheritance>` of the socket's file |
| 1384 | descriptor or socket's handle. |
| 1385 | |
| 1386 | .. versionadded:: 3.4 |
| 1387 | |
| 1388 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1389 | .. method:: socket.setblocking(flag) |
| 1390 | |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 1391 | Set blocking or non-blocking mode of the socket: if *flag* is false, the |
| 1392 | socket is set to non-blocking, else to blocking mode. |
| 1393 | |
| 1394 | This method is a shorthand for certain :meth:`~socket.settimeout` calls: |
| 1395 | |
| 1396 | * ``sock.setblocking(True)`` is equivalent to ``sock.settimeout(None)`` |
| 1397 | |
| 1398 | * ``sock.setblocking(False)`` is equivalent to ``sock.settimeout(0.0)`` |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1399 | |
| 1400 | |
| 1401 | .. method:: socket.settimeout(value) |
| 1402 | |
| 1403 | Set a timeout on blocking socket operations. The *value* argument can be a |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 1404 | nonnegative floating point number expressing seconds, or ``None``. |
| 1405 | If a non-zero value is given, subsequent socket operations will raise a |
| 1406 | :exc:`timeout` exception if the timeout period *value* has elapsed before |
| 1407 | the operation has completed. If zero is given, the socket is put in |
| 1408 | non-blocking mode. If ``None`` is given, the socket is put in blocking mode. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1409 | |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 1410 | For further information, please consult the :ref:`notes on socket timeouts <socket-timeouts>`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1411 | |
| 1412 | |
Christian Heimes | dffa394 | 2016-09-05 23:54:41 +0200 | [diff] [blame] | 1413 | .. method:: socket.setsockopt(level, optname, value: int) |
| 1414 | .. method:: socket.setsockopt(level, optname, value: buffer) |
| 1415 | .. method:: socket.setsockopt(level, optname, None, optlen: int) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1416 | |
| 1417 | .. index:: module: struct |
| 1418 | |
| 1419 | Set the value of the given socket option (see the Unix manual page |
| 1420 | :manpage:`setsockopt(2)`). The needed symbolic constants are defined in the |
Christian Heimes | dffa394 | 2016-09-05 23:54:41 +0200 | [diff] [blame] | 1421 | :mod:`socket` module (:const:`SO_\*` etc.). The value can be an integer, |
Serhiy Storchaka | 989db5c | 2016-10-19 16:37:13 +0300 | [diff] [blame] | 1422 | ``None`` or a :term:`bytes-like object` representing a buffer. In the later |
Christian Heimes | dffa394 | 2016-09-05 23:54:41 +0200 | [diff] [blame] | 1423 | case it is up to the caller to ensure that the bytestring contains the |
| 1424 | proper bits (see the optional built-in module :mod:`struct` for a way to |
Serhiy Storchaka | 989db5c | 2016-10-19 16:37:13 +0300 | [diff] [blame] | 1425 | encode C structures as bytestrings). When value is set to ``None``, |
Christian Heimes | dffa394 | 2016-09-05 23:54:41 +0200 | [diff] [blame] | 1426 | optlen argument is required. It's equivalent to call setsockopt C |
| 1427 | function with optval=NULL and optlen=optlen. |
| 1428 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1429 | |
Georg Brandl | 8c16cb9 | 2016-02-25 20:17:45 +0100 | [diff] [blame] | 1430 | .. versionchanged:: 3.5 |
Serhiy Storchaka | 8490f5a | 2015-03-20 09:00:36 +0200 | [diff] [blame] | 1431 | Writable :term:`bytes-like object` is now accepted. |
| 1432 | |
Christian Heimes | dffa394 | 2016-09-05 23:54:41 +0200 | [diff] [blame] | 1433 | .. versionchanged:: 3.6 |
| 1434 | setsockopt(level, optname, None, optlen: int) form added. |
| 1435 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1436 | |
| 1437 | .. method:: socket.shutdown(how) |
| 1438 | |
| 1439 | Shut down one or both halves of the connection. If *how* is :const:`SHUT_RD`, |
| 1440 | further receives are disallowed. If *how* is :const:`SHUT_WR`, further sends |
| 1441 | are disallowed. If *how* is :const:`SHUT_RDWR`, further sends and receives are |
Charles-François Natali | cdc878e | 2012-01-29 16:42:54 +0100 | [diff] [blame] | 1442 | disallowed. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1443 | |
Kristján Valur Jónsson | 10f383a | 2012-04-07 11:23:31 +0000 | [diff] [blame] | 1444 | |
| 1445 | .. method:: socket.share(process_id) |
| 1446 | |
Antoine Pitrou | a5cc9d6 | 2013-12-04 21:11:03 +0100 | [diff] [blame] | 1447 | Duplicate a socket and prepare it for sharing with a target process. The |
| 1448 | target process must be provided with *process_id*. The resulting bytes object |
| 1449 | can then be passed to the target process using some form of interprocess |
| 1450 | communication and the socket can be recreated there using :func:`fromshare`. |
| 1451 | Once this method has been called, it is safe to close the socket since |
| 1452 | the operating system has already duplicated it for the target process. |
Kristján Valur Jónsson | 10f383a | 2012-04-07 11:23:31 +0000 | [diff] [blame] | 1453 | |
Antoine Pitrou | a5cc9d6 | 2013-12-04 21:11:03 +0100 | [diff] [blame] | 1454 | Availability: Windows. |
Kristján Valur Jónsson | 10f383a | 2012-04-07 11:23:31 +0000 | [diff] [blame] | 1455 | |
| 1456 | .. versionadded:: 3.3 |
| 1457 | |
| 1458 | |
Georg Brandl | 8569e58 | 2010-05-19 20:57:08 +0000 | [diff] [blame] | 1459 | Note that there are no methods :meth:`read` or :meth:`write`; use |
| 1460 | :meth:`~socket.recv` and :meth:`~socket.send` without *flags* argument instead. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1461 | |
| 1462 | Socket objects also have these (read-only) attributes that correspond to the |
Serhiy Storchaka | ee1b01a | 2016-12-02 23:13:53 +0200 | [diff] [blame] | 1463 | values given to the :class:`~socket.socket` constructor. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1464 | |
| 1465 | |
| 1466 | .. attribute:: socket.family |
| 1467 | |
| 1468 | The socket family. |
| 1469 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1470 | |
| 1471 | .. attribute:: socket.type |
| 1472 | |
| 1473 | The socket type. |
| 1474 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1475 | |
| 1476 | .. attribute:: socket.proto |
| 1477 | |
| 1478 | The socket protocol. |
| 1479 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1480 | |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 1481 | |
| 1482 | .. _socket-timeouts: |
| 1483 | |
| 1484 | Notes on socket timeouts |
| 1485 | ------------------------ |
| 1486 | |
| 1487 | A socket object can be in one of three modes: blocking, non-blocking, or |
| 1488 | timeout. Sockets are by default always created in blocking mode, but this |
| 1489 | can be changed by calling :func:`setdefaulttimeout`. |
| 1490 | |
| 1491 | * In *blocking mode*, operations block until complete or the system returns |
| 1492 | an error (such as connection timed out). |
| 1493 | |
| 1494 | * In *non-blocking mode*, operations fail (with an error that is unfortunately |
| 1495 | system-dependent) if they cannot be completed immediately: functions from the |
| 1496 | :mod:`select` can be used to know when and whether a socket is available for |
| 1497 | reading or writing. |
| 1498 | |
| 1499 | * In *timeout mode*, operations fail if they cannot be completed within the |
| 1500 | timeout specified for the socket (they raise a :exc:`timeout` exception) |
| 1501 | or if the system returns an error. |
| 1502 | |
| 1503 | .. note:: |
| 1504 | At the operating system level, sockets in *timeout mode* are internally set |
| 1505 | in non-blocking mode. Also, the blocking and timeout modes are shared between |
| 1506 | file descriptors and socket objects that refer to the same network endpoint. |
| 1507 | This implementation detail can have visible consequences if e.g. you decide |
| 1508 | to use the :meth:`~socket.fileno()` of a socket. |
| 1509 | |
| 1510 | Timeouts and the ``connect`` method |
| 1511 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| 1512 | |
| 1513 | The :meth:`~socket.connect` operation is also subject to the timeout |
| 1514 | setting, and in general it is recommended to call :meth:`~socket.settimeout` |
| 1515 | before calling :meth:`~socket.connect` or pass a timeout parameter to |
| 1516 | :meth:`create_connection`. However, the system network stack may also |
| 1517 | return a connection timeout error of its own regardless of any Python socket |
| 1518 | timeout setting. |
| 1519 | |
| 1520 | Timeouts and the ``accept`` method |
| 1521 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| 1522 | |
| 1523 | If :func:`getdefaulttimeout` is not :const:`None`, sockets returned by |
| 1524 | the :meth:`~socket.accept` method inherit that timeout. Otherwise, the |
| 1525 | behaviour depends on settings of the listening socket: |
| 1526 | |
| 1527 | * if the listening socket is in *blocking mode* or in *timeout mode*, |
| 1528 | the socket returned by :meth:`~socket.accept` is in *blocking mode*; |
| 1529 | |
| 1530 | * if the listening socket is in *non-blocking mode*, whether the socket |
| 1531 | returned by :meth:`~socket.accept` is in blocking or non-blocking mode |
| 1532 | is operating system-dependent. If you want to ensure cross-platform |
| 1533 | behaviour, it is recommended you manually override this setting. |
| 1534 | |
| 1535 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1536 | .. _socket-example: |
| 1537 | |
| 1538 | Example |
| 1539 | ------- |
| 1540 | |
| 1541 | Here are four minimal example programs using the TCP/IP protocol: a server that |
| 1542 | echoes all data that it receives back (servicing only one client), and a client |
Ezio Melotti | c048d98 | 2013-04-17 04:10:26 +0300 | [diff] [blame] | 1543 | using it. Note that a server must perform the sequence :func:`.socket`, |
Georg Brandl | 8569e58 | 2010-05-19 20:57:08 +0000 | [diff] [blame] | 1544 | :meth:`~socket.bind`, :meth:`~socket.listen`, :meth:`~socket.accept` (possibly |
| 1545 | repeating the :meth:`~socket.accept` to service more than one client), while a |
Ezio Melotti | c048d98 | 2013-04-17 04:10:26 +0300 | [diff] [blame] | 1546 | client only needs the sequence :func:`.socket`, :meth:`~socket.connect`. Also |
Senthil Kumaran | 6e13f13 | 2012-02-09 17:54:17 +0800 | [diff] [blame] | 1547 | note that the server does not :meth:`~socket.sendall`/:meth:`~socket.recv` on |
| 1548 | the socket it is listening on but on the new socket returned by |
Georg Brandl | 8569e58 | 2010-05-19 20:57:08 +0000 | [diff] [blame] | 1549 | :meth:`~socket.accept`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1550 | |
| 1551 | The first two examples support IPv4 only. :: |
| 1552 | |
| 1553 | # Echo server program |
| 1554 | import socket |
| 1555 | |
Christian Heimes | 81ee3ef | 2008-05-04 22:42:01 +0000 | [diff] [blame] | 1556 | HOST = '' # Symbolic name meaning all available interfaces |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1557 | PORT = 50007 # Arbitrary non-privileged port |
Martin Panter | e37fc18 | 2016-04-24 04:24:36 +0000 | [diff] [blame] | 1558 | with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s: |
| 1559 | s.bind((HOST, PORT)) |
| 1560 | s.listen(1) |
| 1561 | conn, addr = s.accept() |
| 1562 | with conn: |
| 1563 | print('Connected by', addr) |
| 1564 | while True: |
| 1565 | data = conn.recv(1024) |
| 1566 | if not data: break |
| 1567 | conn.sendall(data) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1568 | |
| 1569 | :: |
| 1570 | |
| 1571 | # Echo client program |
| 1572 | import socket |
| 1573 | |
| 1574 | HOST = 'daring.cwi.nl' # The remote host |
| 1575 | PORT = 50007 # The same port as used by the server |
Martin Panter | e37fc18 | 2016-04-24 04:24:36 +0000 | [diff] [blame] | 1576 | with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s: |
| 1577 | s.connect((HOST, PORT)) |
| 1578 | s.sendall(b'Hello, world') |
| 1579 | data = s.recv(1024) |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 1580 | print('Received', repr(data)) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1581 | |
| 1582 | The next two examples are identical to the above two, but support both IPv4 and |
| 1583 | IPv6. The server side will listen to the first address family available (it |
| 1584 | should listen to both instead). On most of IPv6-ready systems, IPv6 will take |
| 1585 | precedence and the server may not accept IPv4 traffic. The client side will try |
| 1586 | to connect to the all addresses returned as a result of the name resolution, and |
| 1587 | sends traffic to the first one connected successfully. :: |
| 1588 | |
| 1589 | # Echo server program |
| 1590 | import socket |
| 1591 | import sys |
| 1592 | |
Alexandre Vassalotti | 5f8ced2 | 2008-05-16 00:03:33 +0000 | [diff] [blame] | 1593 | HOST = None # Symbolic name meaning all available interfaces |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1594 | PORT = 50007 # Arbitrary non-privileged port |
| 1595 | s = None |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 1596 | for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC, |
| 1597 | socket.SOCK_STREAM, 0, socket.AI_PASSIVE): |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1598 | af, socktype, proto, canonname, sa = res |
| 1599 | try: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1600 | s = socket.socket(af, socktype, proto) |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 1601 | except OSError as msg: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1602 | s = None |
| 1603 | continue |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1604 | try: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1605 | s.bind(sa) |
| 1606 | s.listen(1) |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 1607 | except OSError as msg: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1608 | s.close() |
| 1609 | s = None |
| 1610 | continue |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1611 | break |
| 1612 | if s is None: |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 1613 | print('could not open socket') |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1614 | sys.exit(1) |
| 1615 | conn, addr = s.accept() |
Martin Panter | e37fc18 | 2016-04-24 04:24:36 +0000 | [diff] [blame] | 1616 | with conn: |
| 1617 | print('Connected by', addr) |
| 1618 | while True: |
| 1619 | data = conn.recv(1024) |
| 1620 | if not data: break |
| 1621 | conn.send(data) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1622 | |
| 1623 | :: |
| 1624 | |
| 1625 | # Echo client program |
| 1626 | import socket |
| 1627 | import sys |
| 1628 | |
| 1629 | HOST = 'daring.cwi.nl' # The remote host |
| 1630 | PORT = 50007 # The same port as used by the server |
| 1631 | s = None |
| 1632 | for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC, socket.SOCK_STREAM): |
| 1633 | af, socktype, proto, canonname, sa = res |
| 1634 | try: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1635 | s = socket.socket(af, socktype, proto) |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 1636 | except OSError as msg: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1637 | s = None |
| 1638 | continue |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1639 | try: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1640 | s.connect(sa) |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 1641 | except OSError as msg: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1642 | s.close() |
| 1643 | s = None |
| 1644 | continue |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1645 | break |
| 1646 | if s is None: |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 1647 | print('could not open socket') |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1648 | sys.exit(1) |
Martin Panter | e37fc18 | 2016-04-24 04:24:36 +0000 | [diff] [blame] | 1649 | with s: |
| 1650 | s.sendall(b'Hello, world') |
| 1651 | data = s.recv(1024) |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 1652 | print('Received', repr(data)) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1653 | |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1654 | |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 1655 | The next example shows how to write a very simple network sniffer with raw |
Alexandre Vassalotti | 5f8ced2 | 2008-05-16 00:03:33 +0000 | [diff] [blame] | 1656 | sockets on Windows. The example requires administrator privileges to modify |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1657 | the interface:: |
| 1658 | |
| 1659 | import socket |
| 1660 | |
| 1661 | # the public network interface |
| 1662 | HOST = socket.gethostbyname(socket.gethostname()) |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1663 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1664 | # create a raw socket and bind it to the public interface |
| 1665 | s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_IP) |
| 1666 | s.bind((HOST, 0)) |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1667 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1668 | # Include IP headers |
| 1669 | s.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1) |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1670 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1671 | # receive all packages |
| 1672 | s.ioctl(socket.SIO_RCVALL, socket.RCVALL_ON) |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1673 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1674 | # receive a package |
Neal Norwitz | 752abd0 | 2008-05-13 04:55:24 +0000 | [diff] [blame] | 1675 | print(s.recvfrom(65565)) |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1676 | |
Christian Heimes | c3f30c4 | 2008-02-22 16:37:40 +0000 | [diff] [blame] | 1677 | # disabled promiscuous mode |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1678 | s.ioctl(socket.SIO_RCVALL, socket.RCVALL_OFF) |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 1679 | |
Pier-Yves Lessard | a30f6d4 | 2017-08-28 04:32:44 -0400 | [diff] [blame] | 1680 | The next example shows how to use the socket interface to communicate to a CAN |
Charles-François Natali | 773e42d | 2013-02-05 19:42:01 +0100 | [diff] [blame] | 1681 | network using the raw socket protocol. To use CAN with the broadcast |
| 1682 | manager protocol instead, open a socket with:: |
| 1683 | |
| 1684 | socket.socket(socket.AF_CAN, socket.SOCK_DGRAM, socket.CAN_BCM) |
| 1685 | |
| 1686 | After binding (:const:`CAN_RAW`) or connecting (:const:`CAN_BCM`) the socket, you |
Mark Dickinson | d80b16d | 2013-02-10 18:43:16 +0000 | [diff] [blame] | 1687 | can use the :meth:`socket.send`, and the :meth:`socket.recv` operations (and |
Charles-François Natali | 773e42d | 2013-02-05 19:42:01 +0100 | [diff] [blame] | 1688 | their counterparts) on the socket object as usual. |
| 1689 | |
Pier-Yves Lessard | a30f6d4 | 2017-08-28 04:32:44 -0400 | [diff] [blame] | 1690 | This last example might require special privileges:: |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 1691 | |
| 1692 | import socket |
| 1693 | import struct |
| 1694 | |
| 1695 | |
Georg Brandl | a673eb8 | 2012-03-04 16:17:05 +0100 | [diff] [blame] | 1696 | # CAN frame packing/unpacking (see 'struct can_frame' in <linux/can.h>) |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 1697 | |
| 1698 | can_frame_fmt = "=IB3x8s" |
Victor Stinner | b09460f | 2011-10-06 20:27:20 +0200 | [diff] [blame] | 1699 | can_frame_size = struct.calcsize(can_frame_fmt) |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 1700 | |
| 1701 | def build_can_frame(can_id, data): |
| 1702 | can_dlc = len(data) |
| 1703 | data = data.ljust(8, b'\x00') |
| 1704 | return struct.pack(can_frame_fmt, can_id, can_dlc, data) |
| 1705 | |
| 1706 | def dissect_can_frame(frame): |
| 1707 | can_id, can_dlc, data = struct.unpack(can_frame_fmt, frame) |
| 1708 | return (can_id, can_dlc, data[:can_dlc]) |
| 1709 | |
| 1710 | |
Georg Brandl | a673eb8 | 2012-03-04 16:17:05 +0100 | [diff] [blame] | 1711 | # create a raw socket and bind it to the 'vcan0' interface |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 1712 | s = socket.socket(socket.AF_CAN, socket.SOCK_RAW, socket.CAN_RAW) |
| 1713 | s.bind(('vcan0',)) |
| 1714 | |
| 1715 | while True: |
Victor Stinner | b09460f | 2011-10-06 20:27:20 +0200 | [diff] [blame] | 1716 | cf, addr = s.recvfrom(can_frame_size) |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 1717 | |
| 1718 | print('Received: can_id=%x, can_dlc=%x, data=%s' % dissect_can_frame(cf)) |
| 1719 | |
| 1720 | try: |
| 1721 | s.send(cf) |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 1722 | except OSError: |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 1723 | print('Error sending CAN frame') |
| 1724 | |
| 1725 | try: |
| 1726 | s.send(build_can_frame(0x01, b'\x01\x02\x03')) |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 1727 | except OSError: |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 1728 | print('Error sending CAN frame') |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 1729 | |
Sandro Tosi | 172f374 | 2011-09-02 20:06:31 +0200 | [diff] [blame] | 1730 | Running an example several times with too small delay between executions, could |
| 1731 | lead to this error:: |
| 1732 | |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 1733 | OSError: [Errno 98] Address already in use |
Sandro Tosi | 172f374 | 2011-09-02 20:06:31 +0200 | [diff] [blame] | 1734 | |
| 1735 | This is because the previous execution has left the socket in a ``TIME_WAIT`` |
| 1736 | state, and can't be immediately reused. |
| 1737 | |
| 1738 | There is a :mod:`socket` flag to set, in order to prevent this, |
| 1739 | :data:`socket.SO_REUSEADDR`:: |
| 1740 | |
| 1741 | s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) |
| 1742 | s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) |
| 1743 | s.bind((HOST, PORT)) |
| 1744 | |
| 1745 | the :data:`SO_REUSEADDR` flag tells the kernel to reuse a local socket in |
| 1746 | ``TIME_WAIT`` state, without waiting for its natural timeout to expire. |
| 1747 | |
| 1748 | |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 1749 | .. seealso:: |
| 1750 | |
| 1751 | For an introduction to socket programming (in C), see the following papers: |
| 1752 | |
| 1753 | - *An Introductory 4.3BSD Interprocess Communication Tutorial*, by Stuart Sechrest |
| 1754 | |
| 1755 | - *An Advanced 4.3BSD Interprocess Communication Tutorial*, by Samuel J. Leffler et |
| 1756 | al, |
| 1757 | |
| 1758 | both in the UNIX Programmer's Manual, Supplementary Documents 1 (sections |
| 1759 | PS1:7 and PS1:8). The platform-specific reference material for the various |
| 1760 | socket-related system calls are also a valuable source of information on the |
| 1761 | details of socket semantics. For Unix, refer to the manual pages; for Windows, |
| 1762 | see the WinSock (or Winsock 2) specification. For IPv6-ready APIs, readers may |
| 1763 | want to refer to :rfc:`3493` titled Basic Socket Interface Extensions for IPv6. |