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 | |
| 7 | |
| 8 | This module provides access to the BSD *socket* interface. It is available on |
Skip Montanaro | eb33e5a | 2007-08-17 12:57:41 +0000 | [diff] [blame] | 9 | all modern Unix systems, Windows, MacOS, OS/2, and probably additional |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 10 | platforms. |
| 11 | |
| 12 | .. note:: |
| 13 | |
| 14 | Some behavior may be platform dependent, since calls are made to the operating |
| 15 | system socket APIs. |
| 16 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 17 | .. index:: object: socket |
| 18 | |
| 19 | The Python interface is a straightforward transliteration of the Unix system |
| 20 | call and library interface for sockets to Python's object-oriented style: the |
| 21 | :func:`socket` function returns a :dfn:`socket object` whose methods implement |
| 22 | the various socket system calls. Parameter types are somewhat higher-level than |
| 23 | in the C interface: as with :meth:`read` and :meth:`write` operations on Python |
| 24 | files, buffer allocation on receive operations is automatic, and buffer length |
| 25 | is implicit on send operations. |
| 26 | |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 27 | |
Antoine Pitrou | e1bc898 | 2011-01-02 22:12:22 +0000 | [diff] [blame] | 28 | .. seealso:: |
| 29 | |
| 30 | Module :mod:`socketserver` |
| 31 | Classes that simplify writing network servers. |
| 32 | |
| 33 | Module :mod:`ssl` |
| 34 | A TLS/SSL wrapper for socket objects. |
| 35 | |
| 36 | |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 37 | Socket families |
| 38 | --------------- |
| 39 | |
| 40 | Depending on the system and the build options, various socket families |
| 41 | are supported by this module. |
| 42 | |
Antoine Pitrou | 6ec29e2 | 2011-12-16 14:46:36 +0100 | [diff] [blame] | 43 | The address format required by a particular socket object is automatically |
| 44 | selected based on the address family specified when the socket object was |
| 45 | created. Socket addresses are represented as follows: |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 46 | |
Antoine Pitrou | 6ec29e2 | 2011-12-16 14:46:36 +0100 | [diff] [blame] | 47 | - The address of an :const:`AF_UNIX` socket bound to a file system node |
| 48 | is represented as a string, using the file system encoding and the |
| 49 | ``'surrogateescape'`` error handler (see :pep:`383`). An address in |
| 50 | Linux's abstract namespace is returned as a :class:`bytes` object with |
| 51 | an initial null byte; note that sockets in this namespace can |
| 52 | communicate with normal file system sockets, so programs intended to |
| 53 | run on Linux may need to deal with both types of address. A string or |
| 54 | :class:`bytes` object can be used for either type of address when |
| 55 | passing it as an argument. |
| 56 | |
| 57 | .. versionchanged:: 3.3 |
| 58 | Previously, :const:`AF_UNIX` socket paths were assumed to use UTF-8 |
| 59 | encoding. |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 60 | |
| 61 | - A pair ``(host, port)`` is used for the :const:`AF_INET` address family, |
| 62 | where *host* is a string representing either a hostname in Internet domain |
| 63 | notation like ``'daring.cwi.nl'`` or an IPv4 address like ``'100.50.200.5'``, |
| 64 | and *port* is an integral port number. |
| 65 | |
| 66 | - For :const:`AF_INET6` address family, a four-tuple ``(host, port, flowinfo, |
| 67 | scopeid)`` is used, where *flowinfo* and *scopeid* represent the ``sin6_flowinfo`` |
| 68 | and ``sin6_scope_id`` members in :const:`struct sockaddr_in6` in C. For |
| 69 | :mod:`socket` module methods, *flowinfo* and *scopeid* can be omitted just for |
| 70 | backward compatibility. Note, however, omission of *scopeid* can cause problems |
| 71 | in manipulating scoped IPv6 addresses. |
| 72 | |
| 73 | - :const:`AF_NETLINK` sockets are represented as pairs ``(pid, groups)``. |
| 74 | |
| 75 | - Linux-only support for TIPC is available using the :const:`AF_TIPC` |
| 76 | address family. TIPC is an open, non-IP based networked protocol designed |
| 77 | for use in clustered computer environments. Addresses are represented by a |
| 78 | tuple, and the fields depend on the address type. The general tuple form is |
| 79 | ``(addr_type, v1, v2, v3 [, scope])``, where: |
| 80 | |
Éric Araujo | c4d7d8c | 2011-11-29 16:46:38 +0100 | [diff] [blame] | 81 | - *addr_type* is one of :const:`TIPC_ADDR_NAMESEQ`, :const:`TIPC_ADDR_NAME`, |
| 82 | or :const:`TIPC_ADDR_ID`. |
| 83 | - *scope* is one of :const:`TIPC_ZONE_SCOPE`, :const:`TIPC_CLUSTER_SCOPE`, and |
| 84 | :const:`TIPC_NODE_SCOPE`. |
| 85 | - 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] | 86 | the port identifier, and *v3* should be 0. |
| 87 | |
Éric Araujo | c4d7d8c | 2011-11-29 16:46:38 +0100 | [diff] [blame] | 88 | 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] | 89 | is the lower port number, and *v3* is the upper port number. |
| 90 | |
Éric Araujo | c4d7d8c | 2011-11-29 16:46:38 +0100 | [diff] [blame] | 91 | 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] | 92 | reference, and *v3* should be set to 0. |
| 93 | |
Éric Araujo | c4d7d8c | 2011-11-29 16:46:38 +0100 | [diff] [blame] | 94 | 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] | 95 | reference, and *v3* should be set to 0. |
| 96 | |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 97 | - A tuple ``(interface, )`` is used for the :const:`AF_CAN` address family, |
| 98 | where *interface* is a string representing a network interface name like |
| 99 | ``'can0'``. The network interface name ``''`` can be used to receive packets |
| 100 | from all network interfaces of this family. |
| 101 | |
Martin v. Löwis | 9d6c669 | 2012-02-03 17:44:58 +0100 | [diff] [blame] | 102 | - A string or a tuple ``(id, unit)`` is used for the :const:`SYSPROTO_CONTROL` |
| 103 | protocol of the :const:`PF_SYSTEM` family. The string is the name of a |
| 104 | kernel control using a dynamically-assigned ID. The tuple can be used if ID |
| 105 | and unit number of the kernel control are known or if a registered ID is |
| 106 | used. |
| 107 | |
| 108 | .. versionadded:: 3.3 |
| 109 | |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 110 | - Certain other address families (:const:`AF_BLUETOOTH`, :const:`AF_PACKET`) |
| 111 | support specific representations. |
| 112 | |
| 113 | .. XXX document them! |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 114 | |
| 115 | For IPv4 addresses, two special forms are accepted instead of a host address: |
| 116 | the empty string represents :const:`INADDR_ANY`, and the string |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 117 | ``'<broadcast>'`` represents :const:`INADDR_BROADCAST`. This behavior is not |
| 118 | compatible with IPv6, therefore, you may want to avoid these if you intend |
| 119 | to support IPv6 with your Python programs. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 120 | |
| 121 | If you use a hostname in the *host* portion of IPv4/v6 socket address, the |
| 122 | program may show a nondeterministic behavior, as Python uses the first address |
| 123 | returned from the DNS resolution. The socket address will be resolved |
| 124 | differently into an actual IPv4/v6 address, depending on the results from DNS |
| 125 | resolution and/or the host configuration. For deterministic behavior use a |
| 126 | numeric address in *host* portion. |
| 127 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 128 | All errors raise exceptions. The normal exceptions for invalid argument types |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 129 | and out-of-memory conditions can be raised; starting from Python 3.3, errors |
| 130 | related to socket or address semantics raise :exc:`OSError` or one of its |
| 131 | subclasses (they used to raise :exc:`socket.error`). |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 132 | |
Georg Brandl | 8569e58 | 2010-05-19 20:57:08 +0000 | [diff] [blame] | 133 | Non-blocking mode is supported through :meth:`~socket.setblocking`. A |
| 134 | generalization of this based on timeouts is supported through |
| 135 | :meth:`~socket.settimeout`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 136 | |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 137 | |
| 138 | Module contents |
| 139 | --------------- |
| 140 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 141 | The module :mod:`socket` exports the following constants and functions: |
| 142 | |
| 143 | |
| 144 | .. exception:: error |
| 145 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 146 | A deprecated alias of :exc:`OSError`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 147 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 148 | .. versionchanged:: 3.3 |
| 149 | Following :pep:`3151`, this class was made an alias of :exc:`OSError`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 150 | |
| 151 | |
| 152 | .. exception:: herror |
| 153 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 154 | A subclass of :exc:`OSError`, this exception is raised for |
Antoine Pitrou | f06576d | 2011-02-28 22:38:07 +0000 | [diff] [blame] | 155 | address-related errors, i.e. for functions that use *h_errno* in the POSIX |
| 156 | C API, including :func:`gethostbyname_ex` and :func:`gethostbyaddr`. |
| 157 | The accompanying value is a pair ``(h_errno, string)`` representing an |
| 158 | error returned by a library call. *h_errno* is a numeric value, while |
| 159 | *string* represents the description of *h_errno*, as returned by the |
| 160 | :c:func:`hstrerror` C function. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 161 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 162 | .. versionchanged:: 3.3 |
| 163 | This class was made a subclass of :exc:`OSError`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 164 | |
| 165 | .. exception:: gaierror |
| 166 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 167 | A subclass of :exc:`OSError`, this exception is raised for |
Antoine Pitrou | f06576d | 2011-02-28 22:38:07 +0000 | [diff] [blame] | 168 | address-related errors by :func:`getaddrinfo` and :func:`getnameinfo`. |
| 169 | The accompanying value is a pair ``(error, string)`` representing an error |
| 170 | returned by a library call. *string* represents the description of |
| 171 | *error*, as returned by the :c:func:`gai_strerror` C function. The |
| 172 | numeric *error* value will match one of the :const:`EAI_\*` constants |
| 173 | defined in this module. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 174 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 175 | .. versionchanged:: 3.3 |
| 176 | This class was made a subclass of :exc:`OSError`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 177 | |
| 178 | .. exception:: timeout |
| 179 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 180 | A subclass of :exc:`OSError`, this exception is raised when a timeout |
Antoine Pitrou | f06576d | 2011-02-28 22:38:07 +0000 | [diff] [blame] | 181 | occurs on a socket which has had timeouts enabled via a prior call to |
| 182 | :meth:`~socket.settimeout` (or implicitly through |
| 183 | :func:`~socket.setdefaulttimeout`). The accompanying value is a string |
| 184 | whose value is currently always "timed out". |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 185 | |
Antoine Pitrou | 70fa31c | 2011-10-12 16:20:53 +0200 | [diff] [blame] | 186 | .. versionchanged:: 3.3 |
| 187 | This class was made a subclass of :exc:`OSError`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 188 | |
| 189 | .. data:: AF_UNIX |
| 190 | AF_INET |
| 191 | AF_INET6 |
| 192 | |
| 193 | These constants represent the address (and protocol) families, used for the |
| 194 | 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] | 195 | defined then this protocol is unsupported. More constants may be available |
| 196 | depending on the system. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 197 | |
| 198 | |
| 199 | .. data:: SOCK_STREAM |
| 200 | SOCK_DGRAM |
| 201 | SOCK_RAW |
| 202 | SOCK_RDM |
| 203 | SOCK_SEQPACKET |
| 204 | |
| 205 | These constants represent the socket types, used for the second argument to |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 206 | :func:`socket`. More constants may be available depending on the system. |
| 207 | (Only :const:`SOCK_STREAM` and :const:`SOCK_DGRAM` appear to be generally |
| 208 | useful.) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 209 | |
Antoine Pitrou | b1c5496 | 2010-10-14 15:05:38 +0000 | [diff] [blame] | 210 | .. data:: SOCK_CLOEXEC |
| 211 | SOCK_NONBLOCK |
| 212 | |
| 213 | These two constants, if defined, can be combined with the socket types and |
| 214 | allow you to set some flags atomically (thus avoiding possible race |
| 215 | conditions and the need for separate calls). |
| 216 | |
| 217 | .. seealso:: |
| 218 | |
| 219 | `Secure File Descriptor Handling <http://udrepper.livejournal.com/20407.html>`_ |
| 220 | for a more thorough explanation. |
| 221 | |
| 222 | Availability: Linux >= 2.6.27. |
| 223 | |
| 224 | .. versionadded:: 3.2 |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 225 | |
| 226 | .. data:: SO_* |
| 227 | SOMAXCONN |
| 228 | MSG_* |
| 229 | SOL_* |
Nick Coghlan | 96fe56a | 2011-08-22 11:55:57 +1000 | [diff] [blame] | 230 | SCM_* |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 231 | IPPROTO_* |
| 232 | IPPORT_* |
| 233 | INADDR_* |
| 234 | IP_* |
| 235 | IPV6_* |
| 236 | EAI_* |
| 237 | AI_* |
| 238 | NI_* |
| 239 | TCP_* |
| 240 | |
| 241 | Many constants of these forms, documented in the Unix documentation on sockets |
| 242 | and/or the IP protocol, are also defined in the socket module. They are |
| 243 | generally used in arguments to the :meth:`setsockopt` and :meth:`getsockopt` |
| 244 | methods of socket objects. In most cases, only those symbols that are defined |
| 245 | in the Unix header files are defined; for a few symbols, default values are |
| 246 | provided. |
| 247 | |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 248 | .. data:: AF_CAN |
| 249 | PF_CAN |
| 250 | SOL_CAN_* |
| 251 | CAN_* |
| 252 | |
| 253 | Many constants of these forms, documented in the Linux documentation, are |
| 254 | also defined in the socket module. |
| 255 | |
| 256 | Availability: Linux >= 2.6.25. |
| 257 | |
| 258 | .. versionadded:: 3.3 |
| 259 | |
| 260 | |
Charles-François Natali | 10b8cf4 | 2011-11-10 19:21:37 +0100 | [diff] [blame] | 261 | .. data:: AF_RDS |
| 262 | PF_RDS |
| 263 | SOL_RDS |
| 264 | RDS_* |
| 265 | |
| 266 | Many constants of these forms, documented in the Linux documentation, are |
| 267 | also defined in the socket module. |
| 268 | |
| 269 | Availability: Linux >= 2.6.30. |
| 270 | |
| 271 | .. versionadded:: 3.3 |
| 272 | |
| 273 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 274 | .. data:: SIO_* |
| 275 | RCVALL_* |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 276 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 277 | Constants for Windows' WSAIoctl(). The constants are used as arguments to the |
| 278 | :meth:`ioctl` method of socket objects. |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 279 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 280 | |
Christian Heimes | 043d6f6 | 2008-01-07 17:19:16 +0000 | [diff] [blame] | 281 | .. data:: TIPC_* |
| 282 | |
| 283 | TIPC related constants, matching the ones exported by the C socket API. See |
| 284 | the TIPC documentation for more information. |
| 285 | |
| 286 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 287 | .. data:: has_ipv6 |
| 288 | |
| 289 | This constant contains a boolean value which indicates if IPv6 is supported on |
| 290 | this platform. |
| 291 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 292 | |
Gregory P. Smith | b406637 | 2010-01-03 03:28:29 +0000 | [diff] [blame] | 293 | .. function:: create_connection(address[, timeout[, source_address]]) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 294 | |
Antoine Pitrou | 889a510 | 2012-01-12 08:06:19 +0100 | [diff] [blame] | 295 | Connect to a TCP service listening on the Internet *address* (a 2-tuple |
| 296 | ``(host, port)``), and return the socket object. This is a higher-level |
| 297 | function than :meth:`socket.connect`: if *host* is a non-numeric hostname, |
| 298 | it will try to resolve it for both :data:`AF_INET` and :data:`AF_INET6`, |
| 299 | and then try to connect to all possible addresses in turn until a |
| 300 | connection succeeds. This makes it easy to write clients that are |
| 301 | compatible to both IPv4 and IPv6. |
| 302 | |
| 303 | Passing the optional *timeout* parameter will set the timeout on the |
| 304 | socket instance before attempting to connect. If no *timeout* is |
| 305 | supplied, the global default timeout setting returned by |
Georg Brandl | f78e02b | 2008-06-10 17:40:04 +0000 | [diff] [blame] | 306 | :func:`getdefaulttimeout` is used. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 307 | |
Gregory P. Smith | b406637 | 2010-01-03 03:28:29 +0000 | [diff] [blame] | 308 | If supplied, *source_address* must be a 2-tuple ``(host, port)`` for the |
| 309 | socket to bind to as its source address before connecting. If host or port |
| 310 | are '' or 0 respectively the OS default behavior will be used. |
| 311 | |
| 312 | .. versionchanged:: 3.2 |
| 313 | *source_address* was added. |
| 314 | |
Giampaolo Rodolà | b383dbb | 2010-09-08 22:44:12 +0000 | [diff] [blame] | 315 | .. versionchanged:: 3.2 |
| 316 | support for the :keyword:`with` statement was added. |
| 317 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 318 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 319 | .. function:: getaddrinfo(host, port, family=0, type=0, proto=0, flags=0) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 320 | |
Antoine Pitrou | 9103597 | 2010-05-31 17:04:40 +0000 | [diff] [blame] | 321 | Translate the *host*/*port* argument into a sequence of 5-tuples that contain |
| 322 | all the necessary arguments for creating a socket connected to that service. |
| 323 | *host* is a domain name, a string representation of an IPv4/v6 address |
| 324 | or ``None``. *port* is a string service name such as ``'http'``, a numeric |
| 325 | port number or ``None``. By passing ``None`` as the value of *host* |
| 326 | and *port*, you can pass ``NULL`` to the underlying C API. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 327 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 328 | The *family*, *type* and *proto* arguments can be optionally specified |
Antoine Pitrou | 9103597 | 2010-05-31 17:04:40 +0000 | [diff] [blame] | 329 | in order to narrow the list of addresses returned. Passing zero as a |
| 330 | value for each of these arguments selects the full range of results. |
| 331 | The *flags* argument can be one or several of the ``AI_*`` constants, |
| 332 | and will influence how results are computed and returned. |
| 333 | For example, :const:`AI_NUMERICHOST` will disable domain name resolution |
| 334 | and will raise an error if *host* is a domain name. |
| 335 | |
| 336 | The function returns a list of 5-tuples with the following structure: |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 337 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 338 | ``(family, type, proto, canonname, sockaddr)`` |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 339 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 340 | In these tuples, *family*, *type*, *proto* are all integers and are |
Antoine Pitrou | 9103597 | 2010-05-31 17:04:40 +0000 | [diff] [blame] | 341 | meant to be passed to the :func:`socket` function. *canonname* will be |
| 342 | a string representing the canonical name of the *host* if |
| 343 | :const:`AI_CANONNAME` is part of the *flags* argument; else *canonname* |
| 344 | will be empty. *sockaddr* is a tuple describing a socket address, whose |
| 345 | format depends on the returned *family* (a ``(address, port)`` 2-tuple for |
| 346 | :const:`AF_INET`, a ``(address, port, flow info, scope id)`` 4-tuple for |
| 347 | :const:`AF_INET6`), and is meant to be passed to the :meth:`socket.connect` |
| 348 | method. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 349 | |
Antoine Pitrou | 9103597 | 2010-05-31 17:04:40 +0000 | [diff] [blame] | 350 | The following example fetches address information for a hypothetical TCP |
| 351 | connection to ``www.python.org`` on port 80 (results may differ on your |
| 352 | system if IPv6 isn't enabled):: |
| 353 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 354 | >>> socket.getaddrinfo("www.python.org", 80, proto=socket.SOL_TCP) |
Antoine Pitrou | 9103597 | 2010-05-31 17:04:40 +0000 | [diff] [blame] | 355 | [(2, 1, 6, '', ('82.94.164.162', 80)), |
| 356 | (10, 1, 6, '', ('2001:888:2000:d::a2', 80, 0, 0))] |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 357 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 358 | .. versionchanged:: 3.2 |
| 359 | parameters can now be passed as single keyword arguments. |
| 360 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 361 | .. function:: getfqdn([name]) |
| 362 | |
| 363 | Return a fully qualified domain name for *name*. If *name* is omitted or empty, |
| 364 | 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] | 365 | hostname returned by :func:`gethostbyaddr` is checked, followed by aliases for the |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 366 | host, if available. The first name which includes a period is selected. In |
| 367 | case no fully qualified domain name is available, the hostname as returned by |
| 368 | :func:`gethostname` is returned. |
| 369 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 370 | |
| 371 | .. function:: gethostbyname(hostname) |
| 372 | |
| 373 | Translate a host name to IPv4 address format. The IPv4 address is returned as a |
| 374 | string, such as ``'100.50.200.5'``. If the host name is an IPv4 address itself |
| 375 | it is returned unchanged. See :func:`gethostbyname_ex` for a more complete |
| 376 | interface. :func:`gethostbyname` does not support IPv6 name resolution, and |
| 377 | :func:`getaddrinfo` should be used instead for IPv4/v6 dual stack support. |
| 378 | |
| 379 | |
| 380 | .. function:: gethostbyname_ex(hostname) |
| 381 | |
| 382 | Translate a host name to IPv4 address format, extended interface. Return a |
| 383 | triple ``(hostname, aliaslist, ipaddrlist)`` where *hostname* is the primary |
| 384 | host name responding to the given *ip_address*, *aliaslist* is a (possibly |
| 385 | empty) list of alternative host names for the same address, and *ipaddrlist* is |
| 386 | a list of IPv4 addresses for the same interface on the same host (often but not |
| 387 | always a single address). :func:`gethostbyname_ex` does not support IPv6 name |
| 388 | resolution, and :func:`getaddrinfo` should be used instead for IPv4/v6 dual |
| 389 | stack support. |
| 390 | |
| 391 | |
| 392 | .. function:: gethostname() |
| 393 | |
| 394 | Return a string containing the hostname of the machine where the Python |
Benjamin Peterson | 65676e4 | 2008-11-05 21:42:45 +0000 | [diff] [blame] | 395 | interpreter is currently executing. |
| 396 | |
| 397 | If you want to know the current machine's IP address, you may want to use |
| 398 | ``gethostbyname(gethostname())``. This operation assumes that there is a |
| 399 | valid address-to-host mapping for the host, and the assumption does not |
| 400 | always hold. |
| 401 | |
| 402 | Note: :func:`gethostname` doesn't always return the fully qualified domain |
| 403 | name; use ``getfqdn()`` (see above). |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 404 | |
| 405 | |
| 406 | .. function:: gethostbyaddr(ip_address) |
| 407 | |
| 408 | Return a triple ``(hostname, aliaslist, ipaddrlist)`` where *hostname* is the |
| 409 | primary host name responding to the given *ip_address*, *aliaslist* is a |
| 410 | (possibly empty) list of alternative host names for the same address, and |
| 411 | *ipaddrlist* is a list of IPv4/v6 addresses for the same interface on the same |
| 412 | host (most likely containing only a single address). To find the fully qualified |
| 413 | domain name, use the function :func:`getfqdn`. :func:`gethostbyaddr` supports |
| 414 | both IPv4 and IPv6. |
| 415 | |
| 416 | |
| 417 | .. function:: getnameinfo(sockaddr, flags) |
| 418 | |
| 419 | Translate a socket address *sockaddr* into a 2-tuple ``(host, port)``. Depending |
| 420 | on the settings of *flags*, the result can contain a fully-qualified domain name |
| 421 | or numeric address representation in *host*. Similarly, *port* can contain a |
| 422 | string port name or a numeric port number. |
| 423 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 424 | |
| 425 | .. function:: getprotobyname(protocolname) |
| 426 | |
| 427 | Translate an Internet protocol name (for example, ``'icmp'``) to a constant |
| 428 | suitable for passing as the (optional) third argument to the :func:`socket` |
| 429 | function. This is usually only needed for sockets opened in "raw" mode |
| 430 | (:const:`SOCK_RAW`); for the normal socket modes, the correct protocol is chosen |
| 431 | automatically if the protocol is omitted or zero. |
| 432 | |
| 433 | |
| 434 | .. function:: getservbyname(servicename[, protocolname]) |
| 435 | |
| 436 | Translate an Internet service name and protocol name to a port number for that |
| 437 | service. The optional protocol name, if given, should be ``'tcp'`` or |
| 438 | ``'udp'``, otherwise any protocol will match. |
| 439 | |
| 440 | |
| 441 | .. function:: getservbyport(port[, protocolname]) |
| 442 | |
| 443 | Translate an Internet port number and protocol name to a service name for that |
| 444 | service. The optional protocol name, if given, should be ``'tcp'`` or |
| 445 | ``'udp'``, otherwise any protocol will match. |
| 446 | |
| 447 | |
| 448 | .. function:: socket([family[, type[, proto]]]) |
| 449 | |
| 450 | Create a new socket using the given address family, socket type and protocol |
| 451 | number. The address family should be :const:`AF_INET` (the default), |
Charles-François Natali | 10b8cf4 | 2011-11-10 19:21:37 +0100 | [diff] [blame] | 452 | :const:`AF_INET6`, :const:`AF_UNIX`, :const:`AF_CAN` or :const:`AF_RDS`. The |
| 453 | socket type should be :const:`SOCK_STREAM` (the default), |
| 454 | :const:`SOCK_DGRAM`, :const:`SOCK_RAW` or perhaps one of the other ``SOCK_`` |
| 455 | constants. The protocol number is usually zero and may be omitted in that |
| 456 | case or :const:`CAN_RAW` in case the address family is :const:`AF_CAN`. |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 457 | |
| 458 | .. versionchanged:: 3.3 |
| 459 | The AF_CAN family was added. |
Charles-François Natali | 10b8cf4 | 2011-11-10 19:21:37 +0100 | [diff] [blame] | 460 | The AF_RDS family was added. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 461 | |
| 462 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 463 | .. function:: socketpair([family[, type[, proto]]]) |
| 464 | |
| 465 | Build a pair of connected socket objects using the given address family, socket |
| 466 | type, and protocol number. Address family, socket type, and protocol number are |
| 467 | as for the :func:`socket` function above. The default family is :const:`AF_UNIX` |
| 468 | if defined on the platform; otherwise, the default is :const:`AF_INET`. |
| 469 | Availability: Unix. |
| 470 | |
Antoine Pitrou | 9e0b864 | 2010-09-14 18:00:02 +0000 | [diff] [blame] | 471 | .. versionchanged:: 3.2 |
| 472 | The returned socket objects now support the whole socket API, rather |
| 473 | than a subset. |
| 474 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 475 | |
| 476 | .. function:: fromfd(fd, family, type[, proto]) |
| 477 | |
| 478 | Duplicate the file descriptor *fd* (an integer as returned by a file object's |
| 479 | :meth:`fileno` method) and build a socket object from the result. Address |
| 480 | family, socket type and protocol number are as for the :func:`socket` function |
| 481 | above. The file descriptor should refer to a socket, but this is not checked --- |
| 482 | subsequent operations on the object may fail if the file descriptor is invalid. |
| 483 | This function is rarely needed, but can be used to get or set socket options on |
| 484 | a socket passed to a program as standard input or output (such as a server |
| 485 | started by the Unix inet daemon). The socket is assumed to be in blocking mode. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 486 | |
| 487 | |
| 488 | .. function:: ntohl(x) |
| 489 | |
| 490 | Convert 32-bit positive integers from network to host byte order. On machines |
| 491 | where the host byte order is the same as network byte order, this is a no-op; |
| 492 | otherwise, it performs a 4-byte swap operation. |
| 493 | |
| 494 | |
| 495 | .. function:: ntohs(x) |
| 496 | |
| 497 | Convert 16-bit positive integers from network to host byte order. On machines |
| 498 | where the host byte order is the same as network byte order, this is a no-op; |
| 499 | otherwise, it performs a 2-byte swap operation. |
| 500 | |
| 501 | |
| 502 | .. function:: htonl(x) |
| 503 | |
| 504 | Convert 32-bit positive integers from host to network byte order. On machines |
| 505 | where the host byte order is the same as network byte order, this is a no-op; |
| 506 | otherwise, it performs a 4-byte swap operation. |
| 507 | |
| 508 | |
| 509 | .. function:: htons(x) |
| 510 | |
| 511 | Convert 16-bit positive integers from host to network byte order. On machines |
| 512 | where the host byte order is the same as network byte order, this is a no-op; |
| 513 | otherwise, it performs a 2-byte swap operation. |
| 514 | |
| 515 | |
| 516 | .. function:: inet_aton(ip_string) |
| 517 | |
| 518 | Convert an IPv4 address from dotted-quad string format (for example, |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 519 | '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] | 520 | 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] | 521 | 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] | 522 | for the 32-bit packed binary this function returns. |
| 523 | |
Georg Brandl | f5123ef | 2009-06-04 10:28:36 +0000 | [diff] [blame] | 524 | :func:`inet_aton` also accepts strings with less than three dots; see the |
| 525 | Unix manual page :manpage:`inet(3)` for details. |
| 526 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 527 | If the IPv4 address string passed to this function is invalid, |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 528 | :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] | 529 | the underlying C implementation of :c:func:`inet_aton`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 530 | |
Georg Brandl | 5f25972 | 2009-05-04 20:50:30 +0000 | [diff] [blame] | 531 | :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] | 532 | instead for IPv4/v6 dual stack support. |
| 533 | |
| 534 | |
| 535 | .. function:: inet_ntoa(packed_ip) |
| 536 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 537 | Convert a 32-bit packed IPv4 address (a bytes object four characters in |
| 538 | length) to its standard dotted-quad string representation (for example, |
| 539 | '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] | 540 | 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] | 541 | is the C type for the 32-bit packed binary data this function takes as an |
| 542 | argument. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 543 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 544 | 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] | 545 | length, :exc:`OSError` will be raised. :func:`inet_ntoa` does not |
Georg Brandl | 5f25972 | 2009-05-04 20:50:30 +0000 | [diff] [blame] | 546 | 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] | 547 | stack support. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 548 | |
| 549 | |
| 550 | .. function:: inet_pton(address_family, ip_string) |
| 551 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 552 | Convert an IP address from its family-specific string format to a packed, |
| 553 | 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] | 554 | calls for an object of type :c:type:`struct in_addr` (similar to |
| 555 | :func:`inet_aton`) or :c:type:`struct in6_addr`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 556 | |
| 557 | Supported values for *address_family* are currently :const:`AF_INET` and |
| 558 | :const:`AF_INET6`. If the IP address string *ip_string* is invalid, |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 559 | :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] | 560 | both the value of *address_family* and the underlying implementation of |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 561 | :c:func:`inet_pton`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 562 | |
| 563 | Availability: Unix (maybe not all platforms). |
| 564 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 565 | |
| 566 | .. function:: inet_ntop(address_family, packed_ip) |
| 567 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 568 | Convert a packed IP address (a bytes object of some number of characters) to its |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 569 | standard, family-specific string representation (for example, ``'7.10.0.5'`` or |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 570 | ``'5aef:2b::8'``). :func:`inet_ntop` is useful when a library or network protocol |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 571 | returns an object of type :c:type:`struct in_addr` (similar to :func:`inet_ntoa`) |
| 572 | or :c:type:`struct in6_addr`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 573 | |
| 574 | Supported values for *address_family* are currently :const:`AF_INET` and |
| 575 | :const:`AF_INET6`. If the string *packed_ip* is not the correct length for the |
| 576 | specified address family, :exc:`ValueError` will be raised. A |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 577 | :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] | 578 | |
| 579 | Availability: Unix (maybe not all platforms). |
| 580 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 581 | |
Nick Coghlan | 96fe56a | 2011-08-22 11:55:57 +1000 | [diff] [blame] | 582 | .. |
| 583 | XXX: Are sendmsg(), recvmsg() and CMSG_*() available on any |
| 584 | non-Unix platforms? The old (obsolete?) 4.2BSD form of the |
| 585 | interface, in which struct msghdr has no msg_control or |
| 586 | msg_controllen members, is not currently supported. |
| 587 | |
| 588 | .. function:: CMSG_LEN(length) |
| 589 | |
| 590 | Return the total length, without trailing padding, of an ancillary |
| 591 | data item with associated data of the given *length*. This value |
| 592 | can often be used as the buffer size for :meth:`~socket.recvmsg` to |
| 593 | receive a single item of ancillary data, but :rfc:`3542` requires |
| 594 | portable applications to use :func:`CMSG_SPACE` and thus include |
| 595 | space for padding, even when the item will be the last in the |
| 596 | buffer. Raises :exc:`OverflowError` if *length* is outside the |
| 597 | permissible range of values. |
| 598 | |
| 599 | Availability: most Unix platforms, possibly others. |
| 600 | |
| 601 | .. versionadded:: 3.3 |
| 602 | |
| 603 | |
| 604 | .. function:: CMSG_SPACE(length) |
| 605 | |
| 606 | Return the buffer size needed for :meth:`~socket.recvmsg` to |
| 607 | receive an ancillary data item with associated data of the given |
| 608 | *length*, along with any trailing padding. The buffer space needed |
| 609 | to receive multiple items is the sum of the :func:`CMSG_SPACE` |
| 610 | values for their associated data lengths. Raises |
| 611 | :exc:`OverflowError` if *length* is outside the permissible range |
| 612 | of values. |
| 613 | |
| 614 | Note that some systems might support ancillary data without |
| 615 | providing this function. Also note that setting the buffer size |
| 616 | using the results of this function may not precisely limit the |
| 617 | amount of ancillary data that can be received, since additional |
| 618 | data may be able to fit into the padding area. |
| 619 | |
| 620 | Availability: most Unix platforms, possibly others. |
| 621 | |
| 622 | .. versionadded:: 3.3 |
| 623 | |
| 624 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 625 | .. function:: getdefaulttimeout() |
| 626 | |
Ezio Melotti | 388c945 | 2011-08-14 08:28:57 +0300 | [diff] [blame] | 627 | 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] | 628 | of ``None`` indicates that new socket objects have no timeout. When the socket |
| 629 | module is first imported, the default is ``None``. |
| 630 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 631 | |
| 632 | .. function:: setdefaulttimeout(timeout) |
| 633 | |
Ezio Melotti | 388c945 | 2011-08-14 08:28:57 +0300 | [diff] [blame] | 634 | Set the default timeout in seconds (float) for new socket objects. When |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 635 | the socket module is first imported, the default is ``None``. See |
| 636 | :meth:`~socket.settimeout` for possible values and their respective |
| 637 | meanings. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 638 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 639 | |
Antoine Pitrou | 061cfb5 | 2011-02-28 22:25:22 +0000 | [diff] [blame] | 640 | .. function:: sethostname(name) |
| 641 | |
| 642 | Set the machine's hostname to *name*. This will raise a |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 643 | :exc:`OSError` if you don't have enough rights. |
Antoine Pitrou | 061cfb5 | 2011-02-28 22:25:22 +0000 | [diff] [blame] | 644 | |
| 645 | Availability: Unix. |
| 646 | |
| 647 | .. versionadded:: 3.3 |
| 648 | |
| 649 | |
Gregory P. Smith | 5ed2e77 | 2011-05-15 00:26:45 -0700 | [diff] [blame] | 650 | .. function:: if_nameindex() |
| 651 | |
Gregory P. Smith | b6471db | 2011-05-22 22:47:55 -0700 | [diff] [blame] | 652 | Return a list of network interface information |
| 653 | (index int, name string) tuples. |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 654 | :exc:`OSError` if the system call fails. |
Gregory P. Smith | 5ed2e77 | 2011-05-15 00:26:45 -0700 | [diff] [blame] | 655 | |
| 656 | Availability: Unix. |
| 657 | |
| 658 | .. versionadded:: 3.3 |
| 659 | |
| 660 | |
| 661 | .. function:: if_nametoindex(if_name) |
| 662 | |
Gregory P. Smith | b6471db | 2011-05-22 22:47:55 -0700 | [diff] [blame] | 663 | Return a network interface index number corresponding to an |
| 664 | interface name. |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 665 | :exc:`OSError` if no interface with the given name exists. |
Gregory P. Smith | 5ed2e77 | 2011-05-15 00:26:45 -0700 | [diff] [blame] | 666 | |
| 667 | Availability: Unix. |
| 668 | |
| 669 | .. versionadded:: 3.3 |
| 670 | |
| 671 | |
| 672 | .. function:: if_indextoname(if_index) |
| 673 | |
Gregory P. Smith | b6471db | 2011-05-22 22:47:55 -0700 | [diff] [blame] | 674 | Return a network interface name corresponding to a |
| 675 | interface index number. |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 676 | :exc:`OSError` if no interface with the given index exists. |
Gregory P. Smith | 5ed2e77 | 2011-05-15 00:26:45 -0700 | [diff] [blame] | 677 | |
| 678 | Availability: Unix. |
| 679 | |
| 680 | .. versionadded:: 3.3 |
| 681 | |
| 682 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 683 | .. data:: SocketType |
| 684 | |
| 685 | This is a Python type object that represents the socket object type. It is the |
| 686 | same as ``type(socket(...))``. |
| 687 | |
| 688 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 689 | .. _socket-objects: |
| 690 | |
| 691 | Socket Objects |
| 692 | -------------- |
| 693 | |
| 694 | Socket objects have the following methods. Except for :meth:`makefile` these |
| 695 | correspond to Unix system calls applicable to sockets. |
| 696 | |
| 697 | |
| 698 | .. method:: socket.accept() |
| 699 | |
| 700 | Accept a connection. The socket must be bound to an address and listening for |
| 701 | connections. The return value is a pair ``(conn, address)`` where *conn* is a |
| 702 | *new* socket object usable to send and receive data on the connection, and |
| 703 | *address* is the address bound to the socket on the other end of the connection. |
| 704 | |
| 705 | |
| 706 | .. method:: socket.bind(address) |
| 707 | |
| 708 | Bind the socket to *address*. The socket must not already be bound. (The format |
| 709 | of *address* depends on the address family --- see above.) |
| 710 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 711 | |
| 712 | .. method:: socket.close() |
| 713 | |
| 714 | Close the socket. All future operations on the socket object will fail. The |
| 715 | remote end will receive no more data (after queued data is flushed). Sockets are |
| 716 | automatically closed when they are garbage-collected. |
| 717 | |
Antoine Pitrou | 4a67a46 | 2011-01-02 22:06:53 +0000 | [diff] [blame] | 718 | .. note:: |
| 719 | :meth:`close()` releases the resource associated with a connection but |
| 720 | does not necessarily close the connection immediately. If you want |
| 721 | to close the connection in a timely fashion, call :meth:`shutdown()` |
| 722 | before :meth:`close()`. |
| 723 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 724 | |
| 725 | .. method:: socket.connect(address) |
| 726 | |
| 727 | Connect to a remote socket at *address*. (The format of *address* depends on the |
| 728 | address family --- see above.) |
| 729 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 730 | |
| 731 | .. method:: socket.connect_ex(address) |
| 732 | |
| 733 | Like ``connect(address)``, but return an error indicator instead of raising an |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 734 | 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] | 735 | problems, such as "host not found," can still raise exceptions). The error |
| 736 | indicator is ``0`` if the operation succeeded, otherwise the value of the |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 737 | :c:data:`errno` variable. This is useful to support, for example, asynchronous |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 738 | connects. |
| 739 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 740 | |
Antoine Pitrou | 6e451df | 2010-08-09 20:39:54 +0000 | [diff] [blame] | 741 | .. method:: socket.detach() |
| 742 | |
| 743 | Put the socket object into closed state without actually closing the |
| 744 | underlying file descriptor. The file descriptor is returned, and can |
| 745 | be reused for other purposes. |
| 746 | |
| 747 | .. versionadded:: 3.2 |
| 748 | |
| 749 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 750 | .. method:: socket.fileno() |
| 751 | |
| 752 | Return the socket's file descriptor (a small integer). This is useful with |
| 753 | :func:`select.select`. |
| 754 | |
| 755 | Under Windows the small integer returned by this method cannot be used where a |
| 756 | file descriptor can be used (such as :func:`os.fdopen`). Unix does not have |
| 757 | this limitation. |
| 758 | |
| 759 | |
| 760 | .. method:: socket.getpeername() |
| 761 | |
| 762 | Return the remote address to which the socket is connected. This is useful to |
| 763 | find out the port number of a remote IPv4/v6 socket, for instance. (The format |
| 764 | of the address returned depends on the address family --- see above.) On some |
| 765 | systems this function is not supported. |
| 766 | |
| 767 | |
| 768 | .. method:: socket.getsockname() |
| 769 | |
| 770 | Return the socket's own address. This is useful to find out the port number of |
| 771 | an IPv4/v6 socket, for instance. (The format of the address returned depends on |
| 772 | the address family --- see above.) |
| 773 | |
| 774 | |
| 775 | .. method:: socket.getsockopt(level, optname[, buflen]) |
| 776 | |
| 777 | Return the value of the given socket option (see the Unix man page |
| 778 | :manpage:`getsockopt(2)`). The needed symbolic constants (:const:`SO_\*` etc.) |
| 779 | are defined in this module. If *buflen* is absent, an integer option is assumed |
| 780 | and its integer value is returned by the function. If *buflen* is present, it |
| 781 | 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] | 782 | 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] | 783 | 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] | 784 | to decode C structures encoded as byte strings). |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 785 | |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 786 | |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 787 | .. method:: socket.gettimeout() |
| 788 | |
Ezio Melotti | 388c945 | 2011-08-14 08:28:57 +0300 | [diff] [blame] | 789 | Return the timeout in seconds (float) associated with socket operations, |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 790 | or ``None`` if no timeout is set. This reflects the last call to |
| 791 | :meth:`setblocking` or :meth:`settimeout`. |
| 792 | |
| 793 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 794 | .. method:: socket.ioctl(control, option) |
| 795 | |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 796 | :platform: Windows |
| 797 | |
Christian Heimes | 679db4a | 2008-01-18 09:56:22 +0000 | [diff] [blame] | 798 | The :meth:`ioctl` method is a limited interface to the WSAIoctl system |
Georg Brandl | 8569e58 | 2010-05-19 20:57:08 +0000 | [diff] [blame] | 799 | interface. Please refer to the `Win32 documentation |
| 800 | <http://msdn.microsoft.com/en-us/library/ms741621%28VS.85%29.aspx>`_ for more |
| 801 | information. |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 802 | |
Alexandre Vassalotti | 6d3dfc3 | 2009-07-29 19:54:39 +0000 | [diff] [blame] | 803 | On other platforms, the generic :func:`fcntl.fcntl` and :func:`fcntl.ioctl` |
| 804 | 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] | 805 | |
| 806 | .. method:: socket.listen(backlog) |
| 807 | |
| 808 | Listen for connections made to the socket. The *backlog* argument specifies the |
Antoine Pitrou | 1be815a | 2011-05-10 19:16:29 +0200 | [diff] [blame] | 809 | maximum number of queued connections and should be at least 0; the maximum value |
| 810 | is system-dependent (usually 5), the minimum value is forced to 0. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 811 | |
| 812 | |
Georg Brandl | e9e8c9b | 2010-12-28 11:49:41 +0000 | [diff] [blame] | 813 | .. method:: socket.makefile(mode='r', buffering=None, *, encoding=None, \ |
| 814 | errors=None, newline=None) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 815 | |
| 816 | .. index:: single: I/O control; buffering |
| 817 | |
Georg Brandl | e9e8c9b | 2010-12-28 11:49:41 +0000 | [diff] [blame] | 818 | Return a :term:`file object` associated with the socket. The exact returned |
| 819 | type depends on the arguments given to :meth:`makefile`. These arguments are |
| 820 | interpreted the same way as by the built-in :func:`open` function. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 821 | |
Georg Brandl | e9e8c9b | 2010-12-28 11:49:41 +0000 | [diff] [blame] | 822 | Closing the file object won't close the socket unless there are no remaining |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 823 | references to the socket. The socket must be in blocking mode; it can have |
| 824 | a timeout, but the file object's internal buffer may end up in a inconsistent |
| 825 | state if a timeout occurs. |
Georg Brandl | e9e8c9b | 2010-12-28 11:49:41 +0000 | [diff] [blame] | 826 | |
| 827 | .. note:: |
| 828 | |
| 829 | On Windows, the file-like object created by :meth:`makefile` cannot be |
| 830 | used where a file object with a file descriptor is expected, such as the |
| 831 | stream arguments of :meth:`subprocess.Popen`. |
Antoine Pitrou | 4adb288 | 2010-01-04 18:50:53 +0000 | [diff] [blame] | 832 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 833 | |
| 834 | .. method:: socket.recv(bufsize[, flags]) |
| 835 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 836 | 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] | 837 | data received. The maximum amount of data to be received at once is specified |
| 838 | by *bufsize*. See the Unix manual page :manpage:`recv(2)` for the meaning of |
| 839 | the optional argument *flags*; it defaults to zero. |
| 840 | |
| 841 | .. note:: |
| 842 | |
| 843 | For best match with hardware and network realities, the value of *bufsize* |
| 844 | should be a relatively small power of 2, for example, 4096. |
| 845 | |
| 846 | |
| 847 | .. method:: socket.recvfrom(bufsize[, flags]) |
| 848 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 849 | Receive data from the socket. The return value is a pair ``(bytes, address)`` |
| 850 | 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] | 851 | address of the socket sending the data. See the Unix manual page |
| 852 | :manpage:`recv(2)` for the meaning of the optional argument *flags*; it defaults |
| 853 | to zero. (The format of *address* depends on the address family --- see above.) |
| 854 | |
| 855 | |
Nick Coghlan | 96fe56a | 2011-08-22 11:55:57 +1000 | [diff] [blame] | 856 | .. method:: socket.recvmsg(bufsize[, ancbufsize[, flags]]) |
| 857 | |
| 858 | Receive normal data (up to *bufsize* bytes) and ancillary data from |
| 859 | the socket. The *ancbufsize* argument sets the size in bytes of |
| 860 | the internal buffer used to receive the ancillary data; it defaults |
| 861 | to 0, meaning that no ancillary data will be received. Appropriate |
| 862 | buffer sizes for ancillary data can be calculated using |
| 863 | :func:`CMSG_SPACE` or :func:`CMSG_LEN`, and items which do not fit |
| 864 | into the buffer might be truncated or discarded. The *flags* |
| 865 | argument defaults to 0 and has the same meaning as for |
| 866 | :meth:`recv`. |
| 867 | |
| 868 | The return value is a 4-tuple: ``(data, ancdata, msg_flags, |
| 869 | address)``. The *data* item is a :class:`bytes` object holding the |
| 870 | non-ancillary data received. The *ancdata* item is a list of zero |
| 871 | or more tuples ``(cmsg_level, cmsg_type, cmsg_data)`` representing |
| 872 | the ancillary data (control messages) received: *cmsg_level* and |
| 873 | *cmsg_type* are integers specifying the protocol level and |
| 874 | protocol-specific type respectively, and *cmsg_data* is a |
| 875 | :class:`bytes` object holding the associated data. The *msg_flags* |
| 876 | item is the bitwise OR of various flags indicating conditions on |
| 877 | the received message; see your system documentation for details. |
| 878 | If the receiving socket is unconnected, *address* is the address of |
| 879 | the sending socket, if available; otherwise, its value is |
| 880 | unspecified. |
| 881 | |
| 882 | On some systems, :meth:`sendmsg` and :meth:`recvmsg` can be used to |
| 883 | pass file descriptors between processes over an :const:`AF_UNIX` |
| 884 | socket. When this facility is used (it is often restricted to |
| 885 | :const:`SOCK_STREAM` sockets), :meth:`recvmsg` will return, in its |
| 886 | ancillary data, items of the form ``(socket.SOL_SOCKET, |
| 887 | socket.SCM_RIGHTS, fds)``, where *fds* is a :class:`bytes` object |
| 888 | representing the new file descriptors as a binary array of the |
| 889 | native C :c:type:`int` type. If :meth:`recvmsg` raises an |
| 890 | exception after the system call returns, it will first attempt to |
| 891 | close any file descriptors received via this mechanism. |
| 892 | |
| 893 | Some systems do not indicate the truncated length of ancillary data |
| 894 | items which have been only partially received. If an item appears |
| 895 | to extend beyond the end of the buffer, :meth:`recvmsg` will issue |
| 896 | a :exc:`RuntimeWarning`, and will return the part of it which is |
| 897 | inside the buffer provided it has not been truncated before the |
| 898 | start of its associated data. |
| 899 | |
| 900 | On systems which support the :const:`SCM_RIGHTS` mechanism, the |
| 901 | following function will receive up to *maxfds* file descriptors, |
| 902 | returning the message data and a list containing the descriptors |
| 903 | (while ignoring unexpected conditions such as unrelated control |
| 904 | messages being received). See also :meth:`sendmsg`. :: |
| 905 | |
| 906 | import socket, array |
| 907 | |
| 908 | def recv_fds(sock, msglen, maxfds): |
| 909 | fds = array.array("i") # Array of ints |
| 910 | msg, ancdata, flags, addr = sock.recvmsg(msglen, socket.CMSG_LEN(maxfds * fds.itemsize)) |
| 911 | for cmsg_level, cmsg_type, cmsg_data in ancdata: |
| 912 | if (cmsg_level == socket.SOL_SOCKET and cmsg_type == socket.SCM_RIGHTS): |
| 913 | # Append data, ignoring any truncated integers at the end. |
| 914 | fds.fromstring(cmsg_data[:len(cmsg_data) - (len(cmsg_data) % fds.itemsize)]) |
| 915 | return msg, list(fds) |
| 916 | |
| 917 | Availability: most Unix platforms, possibly others. |
| 918 | |
| 919 | .. versionadded:: 3.3 |
| 920 | |
| 921 | |
| 922 | .. method:: socket.recvmsg_into(buffers[, ancbufsize[, flags]]) |
| 923 | |
| 924 | Receive normal data and ancillary data from the socket, behaving as |
| 925 | :meth:`recvmsg` would, but scatter the non-ancillary data into a |
| 926 | series of buffers instead of returning a new bytes object. The |
| 927 | *buffers* argument must be an iterable of objects that export |
| 928 | writable buffers (e.g. :class:`bytearray` objects); these will be |
| 929 | filled with successive chunks of the non-ancillary data until it |
| 930 | has all been written or there are no more buffers. The operating |
| 931 | system may set a limit (:func:`~os.sysconf` value ``SC_IOV_MAX``) |
| 932 | on the number of buffers that can be used. The *ancbufsize* and |
| 933 | *flags* arguments have the same meaning as for :meth:`recvmsg`. |
| 934 | |
| 935 | The return value is a 4-tuple: ``(nbytes, ancdata, msg_flags, |
| 936 | address)``, where *nbytes* is the total number of bytes of |
| 937 | non-ancillary data written into the buffers, and *ancdata*, |
| 938 | *msg_flags* and *address* are the same as for :meth:`recvmsg`. |
| 939 | |
| 940 | Example:: |
| 941 | |
| 942 | >>> import socket |
| 943 | >>> s1, s2 = socket.socketpair() |
| 944 | >>> b1 = bytearray(b'----') |
| 945 | >>> b2 = bytearray(b'0123456789') |
| 946 | >>> b3 = bytearray(b'--------------') |
| 947 | >>> s1.send(b'Mary had a little lamb') |
| 948 | 22 |
| 949 | >>> s2.recvmsg_into([b1, memoryview(b2)[2:9], b3]) |
| 950 | (22, [], 0, None) |
| 951 | >>> [b1, b2, b3] |
| 952 | [bytearray(b'Mary'), bytearray(b'01 had a 9'), bytearray(b'little lamb---')] |
| 953 | |
| 954 | Availability: most Unix platforms, possibly others. |
| 955 | |
| 956 | .. versionadded:: 3.3 |
| 957 | |
| 958 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 959 | .. method:: socket.recvfrom_into(buffer[, nbytes[, flags]]) |
| 960 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 961 | Receive data from the socket, writing it into *buffer* instead of creating a |
| 962 | 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] | 963 | the number of bytes received and *address* is the address of the socket sending |
| 964 | the data. See the Unix manual page :manpage:`recv(2)` for the meaning of the |
| 965 | optional argument *flags*; it defaults to zero. (The format of *address* |
| 966 | depends on the address family --- see above.) |
| 967 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 968 | |
| 969 | .. method:: socket.recv_into(buffer[, nbytes[, flags]]) |
| 970 | |
| 971 | 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] | 972 | 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] | 973 | receive up to the size available in the given buffer. Returns the number of |
| 974 | bytes received. See the Unix manual page :manpage:`recv(2)` for the meaning |
| 975 | of the optional argument *flags*; it defaults to zero. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 976 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 977 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 978 | .. method:: socket.send(bytes[, flags]) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 979 | |
| 980 | Send data to the socket. The socket must be connected to a remote socket. The |
| 981 | optional *flags* argument has the same meaning as for :meth:`recv` above. |
| 982 | Returns the number of bytes sent. Applications are responsible for checking that |
| 983 | 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] | 984 | application needs to attempt delivery of the remaining data. For further |
| 985 | information on this topic, consult the :ref:`socket-howto`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 986 | |
| 987 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 988 | .. method:: socket.sendall(bytes[, flags]) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 989 | |
| 990 | Send data to the socket. The socket must be connected to a remote socket. The |
| 991 | optional *flags* argument has the same meaning as for :meth:`recv` above. |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 992 | Unlike :meth:`send`, this method continues to send data from *bytes* until |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 993 | either all data has been sent or an error occurs. ``None`` is returned on |
| 994 | success. On error, an exception is raised, and there is no way to determine how |
| 995 | much data, if any, was successfully sent. |
| 996 | |
| 997 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 998 | .. method:: socket.sendto(bytes[, flags], address) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 999 | |
| 1000 | Send data to the socket. The socket should not be connected to a remote socket, |
| 1001 | since the destination socket is specified by *address*. The optional *flags* |
| 1002 | argument has the same meaning as for :meth:`recv` above. Return the number of |
| 1003 | bytes sent. (The format of *address* depends on the address family --- see |
| 1004 | above.) |
| 1005 | |
| 1006 | |
Nick Coghlan | 96fe56a | 2011-08-22 11:55:57 +1000 | [diff] [blame] | 1007 | .. method:: socket.sendmsg(buffers[, ancdata[, flags[, address]]]) |
| 1008 | |
| 1009 | Send normal and ancillary data to the socket, gathering the |
| 1010 | non-ancillary data from a series of buffers and concatenating it |
| 1011 | into a single message. The *buffers* argument specifies the |
| 1012 | non-ancillary data as an iterable of buffer-compatible objects |
| 1013 | (e.g. :class:`bytes` objects); the operating system may set a limit |
| 1014 | (:func:`~os.sysconf` value ``SC_IOV_MAX``) on the number of buffers |
| 1015 | that can be used. The *ancdata* argument specifies the ancillary |
| 1016 | data (control messages) as an iterable of zero or more tuples |
| 1017 | ``(cmsg_level, cmsg_type, cmsg_data)``, where *cmsg_level* and |
| 1018 | *cmsg_type* are integers specifying the protocol level and |
| 1019 | protocol-specific type respectively, and *cmsg_data* is a |
| 1020 | buffer-compatible object holding the associated data. Note that |
| 1021 | some systems (in particular, systems without :func:`CMSG_SPACE`) |
| 1022 | might support sending only one control message per call. The |
| 1023 | *flags* argument defaults to 0 and has the same meaning as for |
| 1024 | :meth:`send`. If *address* is supplied and not ``None``, it sets a |
| 1025 | destination address for the message. The return value is the |
| 1026 | number of bytes of non-ancillary data sent. |
| 1027 | |
| 1028 | The following function sends the list of file descriptors *fds* |
| 1029 | over an :const:`AF_UNIX` socket, on systems which support the |
| 1030 | :const:`SCM_RIGHTS` mechanism. See also :meth:`recvmsg`. :: |
| 1031 | |
| 1032 | import socket, array |
| 1033 | |
| 1034 | def send_fds(sock, msg, fds): |
| 1035 | return sock.sendmsg([msg], [(socket.SOL_SOCKET, socket.SCM_RIGHTS, array.array("i", fds))]) |
| 1036 | |
| 1037 | Availability: most Unix platforms, possibly others. |
| 1038 | |
| 1039 | .. versionadded:: 3.3 |
| 1040 | |
| 1041 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1042 | .. method:: socket.setblocking(flag) |
| 1043 | |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 1044 | Set blocking or non-blocking mode of the socket: if *flag* is false, the |
| 1045 | socket is set to non-blocking, else to blocking mode. |
| 1046 | |
| 1047 | This method is a shorthand for certain :meth:`~socket.settimeout` calls: |
| 1048 | |
| 1049 | * ``sock.setblocking(True)`` is equivalent to ``sock.settimeout(None)`` |
| 1050 | |
| 1051 | * ``sock.setblocking(False)`` is equivalent to ``sock.settimeout(0.0)`` |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1052 | |
| 1053 | |
| 1054 | .. method:: socket.settimeout(value) |
| 1055 | |
| 1056 | 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] | 1057 | nonnegative floating point number expressing seconds, or ``None``. |
| 1058 | If a non-zero value is given, subsequent socket operations will raise a |
| 1059 | :exc:`timeout` exception if the timeout period *value* has elapsed before |
| 1060 | the operation has completed. If zero is given, the socket is put in |
| 1061 | 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] | 1062 | |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 1063 | 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] | 1064 | |
| 1065 | |
| 1066 | .. method:: socket.setsockopt(level, optname, value) |
| 1067 | |
| 1068 | .. index:: module: struct |
| 1069 | |
| 1070 | Set the value of the given socket option (see the Unix manual page |
| 1071 | :manpage:`setsockopt(2)`). The needed symbolic constants are defined in the |
| 1072 | :mod:`socket` module (:const:`SO_\*` etc.). The value can be an integer or a |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 1073 | bytes object representing a buffer. In the latter case it is up to the caller to |
| 1074 | ensure that the bytestring contains the proper bits (see the optional built-in |
| 1075 | module :mod:`struct` for a way to encode C structures as bytestrings). |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1076 | |
| 1077 | |
| 1078 | .. method:: socket.shutdown(how) |
| 1079 | |
| 1080 | Shut down one or both halves of the connection. If *how* is :const:`SHUT_RD`, |
| 1081 | further receives are disallowed. If *how* is :const:`SHUT_WR`, further sends |
| 1082 | 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] | 1083 | disallowed. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1084 | |
Georg Brandl | 8569e58 | 2010-05-19 20:57:08 +0000 | [diff] [blame] | 1085 | Note that there are no methods :meth:`read` or :meth:`write`; use |
| 1086 | :meth:`~socket.recv` and :meth:`~socket.send` without *flags* argument instead. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1087 | |
| 1088 | Socket objects also have these (read-only) attributes that correspond to the |
| 1089 | values given to the :class:`socket` constructor. |
| 1090 | |
| 1091 | |
| 1092 | .. attribute:: socket.family |
| 1093 | |
| 1094 | The socket family. |
| 1095 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1096 | |
| 1097 | .. attribute:: socket.type |
| 1098 | |
| 1099 | The socket type. |
| 1100 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1101 | |
| 1102 | .. attribute:: socket.proto |
| 1103 | |
| 1104 | The socket protocol. |
| 1105 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1106 | |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 1107 | |
| 1108 | .. _socket-timeouts: |
| 1109 | |
| 1110 | Notes on socket timeouts |
| 1111 | ------------------------ |
| 1112 | |
| 1113 | A socket object can be in one of three modes: blocking, non-blocking, or |
| 1114 | timeout. Sockets are by default always created in blocking mode, but this |
| 1115 | can be changed by calling :func:`setdefaulttimeout`. |
| 1116 | |
| 1117 | * In *blocking mode*, operations block until complete or the system returns |
| 1118 | an error (such as connection timed out). |
| 1119 | |
| 1120 | * In *non-blocking mode*, operations fail (with an error that is unfortunately |
| 1121 | system-dependent) if they cannot be completed immediately: functions from the |
| 1122 | :mod:`select` can be used to know when and whether a socket is available for |
| 1123 | reading or writing. |
| 1124 | |
| 1125 | * In *timeout mode*, operations fail if they cannot be completed within the |
| 1126 | timeout specified for the socket (they raise a :exc:`timeout` exception) |
| 1127 | or if the system returns an error. |
| 1128 | |
| 1129 | .. note:: |
| 1130 | At the operating system level, sockets in *timeout mode* are internally set |
| 1131 | in non-blocking mode. Also, the blocking and timeout modes are shared between |
| 1132 | file descriptors and socket objects that refer to the same network endpoint. |
| 1133 | This implementation detail can have visible consequences if e.g. you decide |
| 1134 | to use the :meth:`~socket.fileno()` of a socket. |
| 1135 | |
| 1136 | Timeouts and the ``connect`` method |
| 1137 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| 1138 | |
| 1139 | The :meth:`~socket.connect` operation is also subject to the timeout |
| 1140 | setting, and in general it is recommended to call :meth:`~socket.settimeout` |
| 1141 | before calling :meth:`~socket.connect` or pass a timeout parameter to |
| 1142 | :meth:`create_connection`. However, the system network stack may also |
| 1143 | return a connection timeout error of its own regardless of any Python socket |
| 1144 | timeout setting. |
| 1145 | |
| 1146 | Timeouts and the ``accept`` method |
| 1147 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| 1148 | |
| 1149 | If :func:`getdefaulttimeout` is not :const:`None`, sockets returned by |
| 1150 | the :meth:`~socket.accept` method inherit that timeout. Otherwise, the |
| 1151 | behaviour depends on settings of the listening socket: |
| 1152 | |
| 1153 | * if the listening socket is in *blocking mode* or in *timeout mode*, |
| 1154 | the socket returned by :meth:`~socket.accept` is in *blocking mode*; |
| 1155 | |
| 1156 | * if the listening socket is in *non-blocking mode*, whether the socket |
| 1157 | returned by :meth:`~socket.accept` is in blocking or non-blocking mode |
| 1158 | is operating system-dependent. If you want to ensure cross-platform |
| 1159 | behaviour, it is recommended you manually override this setting. |
| 1160 | |
| 1161 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1162 | .. _socket-example: |
| 1163 | |
| 1164 | Example |
| 1165 | ------- |
| 1166 | |
| 1167 | Here are four minimal example programs using the TCP/IP protocol: a server that |
| 1168 | echoes all data that it receives back (servicing only one client), and a client |
| 1169 | using it. Note that a server must perform the sequence :func:`socket`, |
Georg Brandl | 8569e58 | 2010-05-19 20:57:08 +0000 | [diff] [blame] | 1170 | :meth:`~socket.bind`, :meth:`~socket.listen`, :meth:`~socket.accept` (possibly |
| 1171 | repeating the :meth:`~socket.accept` to service more than one client), while a |
| 1172 | client only needs the sequence :func:`socket`, :meth:`~socket.connect`. Also |
Senthil Kumaran | 6e13f13 | 2012-02-09 17:54:17 +0800 | [diff] [blame] | 1173 | note that the server does not :meth:`~socket.sendall`/:meth:`~socket.recv` on |
| 1174 | 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] | 1175 | :meth:`~socket.accept`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1176 | |
| 1177 | The first two examples support IPv4 only. :: |
| 1178 | |
| 1179 | # Echo server program |
| 1180 | import socket |
| 1181 | |
Christian Heimes | 81ee3ef | 2008-05-04 22:42:01 +0000 | [diff] [blame] | 1182 | HOST = '' # Symbolic name meaning all available interfaces |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1183 | PORT = 50007 # Arbitrary non-privileged port |
| 1184 | s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) |
| 1185 | s.bind((HOST, PORT)) |
| 1186 | s.listen(1) |
| 1187 | conn, addr = s.accept() |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 1188 | print('Connected by', addr) |
Collin Winter | 4633448 | 2007-09-10 00:49:57 +0000 | [diff] [blame] | 1189 | while True: |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1190 | data = conn.recv(1024) |
| 1191 | if not data: break |
Senthil Kumaran | 6e13f13 | 2012-02-09 17:54:17 +0800 | [diff] [blame] | 1192 | conn.sendall(data) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1193 | conn.close() |
| 1194 | |
| 1195 | :: |
| 1196 | |
| 1197 | # Echo client program |
| 1198 | import socket |
| 1199 | |
| 1200 | HOST = 'daring.cwi.nl' # The remote host |
| 1201 | PORT = 50007 # The same port as used by the server |
| 1202 | s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) |
| 1203 | s.connect((HOST, PORT)) |
Senthil Kumaran | 6e13f13 | 2012-02-09 17:54:17 +0800 | [diff] [blame] | 1204 | s.sendall(b'Hello, world') |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1205 | data = s.recv(1024) |
| 1206 | s.close() |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 1207 | print('Received', repr(data)) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1208 | |
| 1209 | The next two examples are identical to the above two, but support both IPv4 and |
| 1210 | IPv6. The server side will listen to the first address family available (it |
| 1211 | should listen to both instead). On most of IPv6-ready systems, IPv6 will take |
| 1212 | precedence and the server may not accept IPv4 traffic. The client side will try |
| 1213 | to connect to the all addresses returned as a result of the name resolution, and |
| 1214 | sends traffic to the first one connected successfully. :: |
| 1215 | |
| 1216 | # Echo server program |
| 1217 | import socket |
| 1218 | import sys |
| 1219 | |
Alexandre Vassalotti | 5f8ced2 | 2008-05-16 00:03:33 +0000 | [diff] [blame] | 1220 | HOST = None # Symbolic name meaning all available interfaces |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1221 | PORT = 50007 # Arbitrary non-privileged port |
| 1222 | s = None |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 1223 | for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC, |
| 1224 | socket.SOCK_STREAM, 0, socket.AI_PASSIVE): |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1225 | af, socktype, proto, canonname, sa = res |
| 1226 | try: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1227 | s = socket.socket(af, socktype, proto) |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 1228 | except OSError as msg: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1229 | s = None |
| 1230 | continue |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1231 | try: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1232 | s.bind(sa) |
| 1233 | s.listen(1) |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 1234 | except OSError as msg: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1235 | s.close() |
| 1236 | s = None |
| 1237 | continue |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1238 | break |
| 1239 | if s is None: |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 1240 | print('could not open socket') |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1241 | sys.exit(1) |
| 1242 | conn, addr = s.accept() |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 1243 | print('Connected by', addr) |
Collin Winter | 4633448 | 2007-09-10 00:49:57 +0000 | [diff] [blame] | 1244 | while True: |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1245 | data = conn.recv(1024) |
| 1246 | if not data: break |
| 1247 | conn.send(data) |
| 1248 | conn.close() |
| 1249 | |
| 1250 | :: |
| 1251 | |
| 1252 | # Echo client program |
| 1253 | import socket |
| 1254 | import sys |
| 1255 | |
| 1256 | HOST = 'daring.cwi.nl' # The remote host |
| 1257 | PORT = 50007 # The same port as used by the server |
| 1258 | s = None |
| 1259 | for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC, socket.SOCK_STREAM): |
| 1260 | af, socktype, proto, canonname, sa = res |
| 1261 | try: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1262 | s = socket.socket(af, socktype, proto) |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 1263 | except OSError as msg: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1264 | s = None |
| 1265 | continue |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1266 | try: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1267 | s.connect(sa) |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 1268 | except OSError as msg: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 1269 | s.close() |
| 1270 | s = None |
| 1271 | continue |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1272 | break |
| 1273 | if s is None: |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 1274 | print('could not open socket') |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1275 | sys.exit(1) |
Senthil Kumaran | 6e13f13 | 2012-02-09 17:54:17 +0800 | [diff] [blame] | 1276 | s.sendall(b'Hello, world') |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1277 | data = s.recv(1024) |
| 1278 | s.close() |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 1279 | print('Received', repr(data)) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 1280 | |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1281 | |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 1282 | 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] | 1283 | sockets on Windows. The example requires administrator privileges to modify |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1284 | the interface:: |
| 1285 | |
| 1286 | import socket |
| 1287 | |
| 1288 | # the public network interface |
| 1289 | HOST = socket.gethostbyname(socket.gethostname()) |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1290 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1291 | # create a raw socket and bind it to the public interface |
| 1292 | s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_IP) |
| 1293 | s.bind((HOST, 0)) |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1294 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1295 | # Include IP headers |
| 1296 | s.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1) |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1297 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1298 | # receive all packages |
| 1299 | s.ioctl(socket.SIO_RCVALL, socket.RCVALL_ON) |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1300 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1301 | # receive a package |
Neal Norwitz | 752abd0 | 2008-05-13 04:55:24 +0000 | [diff] [blame] | 1302 | print(s.recvfrom(65565)) |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1303 | |
Christian Heimes | c3f30c4 | 2008-02-22 16:37:40 +0000 | [diff] [blame] | 1304 | # disabled promiscuous mode |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1305 | s.ioctl(socket.SIO_RCVALL, socket.RCVALL_OFF) |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 1306 | |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 1307 | The last example shows how to use the socket interface to communicate to a CAN |
| 1308 | network. This example might require special priviledge:: |
| 1309 | |
| 1310 | import socket |
| 1311 | import struct |
| 1312 | |
| 1313 | |
Georg Brandl | a673eb8 | 2012-03-04 16:17:05 +0100 | [diff] [blame] | 1314 | # 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] | 1315 | |
| 1316 | can_frame_fmt = "=IB3x8s" |
Victor Stinner | b09460f | 2011-10-06 20:27:20 +0200 | [diff] [blame] | 1317 | can_frame_size = struct.calcsize(can_frame_fmt) |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 1318 | |
| 1319 | def build_can_frame(can_id, data): |
| 1320 | can_dlc = len(data) |
| 1321 | data = data.ljust(8, b'\x00') |
| 1322 | return struct.pack(can_frame_fmt, can_id, can_dlc, data) |
| 1323 | |
| 1324 | def dissect_can_frame(frame): |
| 1325 | can_id, can_dlc, data = struct.unpack(can_frame_fmt, frame) |
| 1326 | return (can_id, can_dlc, data[:can_dlc]) |
| 1327 | |
| 1328 | |
Georg Brandl | a673eb8 | 2012-03-04 16:17:05 +0100 | [diff] [blame] | 1329 | # create a raw socket and bind it to the 'vcan0' interface |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 1330 | s = socket.socket(socket.AF_CAN, socket.SOCK_RAW, socket.CAN_RAW) |
| 1331 | s.bind(('vcan0',)) |
| 1332 | |
| 1333 | while True: |
Victor Stinner | b09460f | 2011-10-06 20:27:20 +0200 | [diff] [blame] | 1334 | cf, addr = s.recvfrom(can_frame_size) |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 1335 | |
| 1336 | print('Received: can_id=%x, can_dlc=%x, data=%s' % dissect_can_frame(cf)) |
| 1337 | |
| 1338 | try: |
| 1339 | s.send(cf) |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 1340 | except OSError: |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 1341 | print('Error sending CAN frame') |
| 1342 | |
| 1343 | try: |
| 1344 | s.send(build_can_frame(0x01, b'\x01\x02\x03')) |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 1345 | except OSError: |
Charles-François Natali | 47413c1 | 2011-10-06 19:47:44 +0200 | [diff] [blame] | 1346 | print('Error sending CAN frame') |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 1347 | |
Sandro Tosi | 172f374 | 2011-09-02 20:06:31 +0200 | [diff] [blame] | 1348 | Running an example several times with too small delay between executions, could |
| 1349 | lead to this error:: |
| 1350 | |
Antoine Pitrou | 5574c30 | 2011-10-12 17:53:43 +0200 | [diff] [blame] | 1351 | OSError: [Errno 98] Address already in use |
Sandro Tosi | 172f374 | 2011-09-02 20:06:31 +0200 | [diff] [blame] | 1352 | |
| 1353 | This is because the previous execution has left the socket in a ``TIME_WAIT`` |
| 1354 | state, and can't be immediately reused. |
| 1355 | |
| 1356 | There is a :mod:`socket` flag to set, in order to prevent this, |
| 1357 | :data:`socket.SO_REUSEADDR`:: |
| 1358 | |
| 1359 | s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) |
| 1360 | s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) |
| 1361 | s.bind((HOST, PORT)) |
| 1362 | |
| 1363 | the :data:`SO_REUSEADDR` flag tells the kernel to reuse a local socket in |
| 1364 | ``TIME_WAIT`` state, without waiting for its natural timeout to expire. |
| 1365 | |
| 1366 | |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 1367 | .. seealso:: |
| 1368 | |
| 1369 | For an introduction to socket programming (in C), see the following papers: |
| 1370 | |
| 1371 | - *An Introductory 4.3BSD Interprocess Communication Tutorial*, by Stuart Sechrest |
| 1372 | |
| 1373 | - *An Advanced 4.3BSD Interprocess Communication Tutorial*, by Samuel J. Leffler et |
| 1374 | al, |
| 1375 | |
| 1376 | both in the UNIX Programmer's Manual, Supplementary Documents 1 (sections |
| 1377 | PS1:7 and PS1:8). The platform-specific reference material for the various |
| 1378 | socket-related system calls are also a valuable source of information on the |
| 1379 | details of socket semantics. For Unix, refer to the manual pages; for Windows, |
| 1380 | see the WinSock (or Winsock 2) specification. For IPv6-ready APIs, readers may |
| 1381 | want to refer to :rfc:`3493` titled Basic Socket Interface Extensions for IPv6. |
| 1382 | |