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 | |
| 43 | Socket addresses are represented as follows: |
| 44 | |
| 45 | - A single string is used for the :const:`AF_UNIX` address family. |
| 46 | |
| 47 | - A pair ``(host, port)`` is used for the :const:`AF_INET` address family, |
| 48 | where *host* is a string representing either a hostname in Internet domain |
| 49 | notation like ``'daring.cwi.nl'`` or an IPv4 address like ``'100.50.200.5'``, |
| 50 | and *port* is an integral port number. |
| 51 | |
| 52 | - For :const:`AF_INET6` address family, a four-tuple ``(host, port, flowinfo, |
| 53 | scopeid)`` is used, where *flowinfo* and *scopeid* represent the ``sin6_flowinfo`` |
| 54 | and ``sin6_scope_id`` members in :const:`struct sockaddr_in6` in C. For |
| 55 | :mod:`socket` module methods, *flowinfo* and *scopeid* can be omitted just for |
| 56 | backward compatibility. Note, however, omission of *scopeid* can cause problems |
| 57 | in manipulating scoped IPv6 addresses. |
| 58 | |
| 59 | - :const:`AF_NETLINK` sockets are represented as pairs ``(pid, groups)``. |
| 60 | |
| 61 | - Linux-only support for TIPC is available using the :const:`AF_TIPC` |
| 62 | address family. TIPC is an open, non-IP based networked protocol designed |
| 63 | for use in clustered computer environments. Addresses are represented by a |
| 64 | tuple, and the fields depend on the address type. The general tuple form is |
| 65 | ``(addr_type, v1, v2, v3 [, scope])``, where: |
| 66 | |
| 67 | - *addr_type* is one of TIPC_ADDR_NAMESEQ, TIPC_ADDR_NAME, or |
| 68 | TIPC_ADDR_ID. |
| 69 | - *scope* is one of TIPC_ZONE_SCOPE, TIPC_CLUSTER_SCOPE, and |
| 70 | TIPC_NODE_SCOPE. |
| 71 | - If *addr_type* is TIPC_ADDR_NAME, then *v1* is the server type, *v2* is |
| 72 | the port identifier, and *v3* should be 0. |
| 73 | |
| 74 | If *addr_type* is TIPC_ADDR_NAMESEQ, then *v1* is the server type, *v2* |
| 75 | is the lower port number, and *v3* is the upper port number. |
| 76 | |
| 77 | If *addr_type* is TIPC_ADDR_ID, then *v1* is the node, *v2* is the |
| 78 | reference, and *v3* should be set to 0. |
| 79 | |
| 80 | If *addr_type* is TIPC_ADDR_ID, then *v1* is the node, *v2* is the |
| 81 | reference, and *v3* should be set to 0. |
| 82 | |
| 83 | - Certain other address families (:const:`AF_BLUETOOTH`, :const:`AF_PACKET`) |
| 84 | support specific representations. |
| 85 | |
| 86 | .. XXX document them! |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 87 | |
| 88 | For IPv4 addresses, two special forms are accepted instead of a host address: |
| 89 | the empty string represents :const:`INADDR_ANY`, and the string |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 90 | ``'<broadcast>'`` represents :const:`INADDR_BROADCAST`. This behavior is not |
| 91 | compatible with IPv6, therefore, you may want to avoid these if you intend |
| 92 | to support IPv6 with your Python programs. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 93 | |
| 94 | If you use a hostname in the *host* portion of IPv4/v6 socket address, the |
| 95 | program may show a nondeterministic behavior, as Python uses the first address |
| 96 | returned from the DNS resolution. The socket address will be resolved |
| 97 | differently into an actual IPv4/v6 address, depending on the results from DNS |
| 98 | resolution and/or the host configuration. For deterministic behavior use a |
| 99 | numeric address in *host* portion. |
| 100 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 101 | All errors raise exceptions. The normal exceptions for invalid argument types |
| 102 | and out-of-memory conditions can be raised; errors related to socket or address |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 103 | semantics raise :exc:`socket.error` or one of its subclasses. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 104 | |
Georg Brandl | 8569e58 | 2010-05-19 20:57:08 +0000 | [diff] [blame] | 105 | Non-blocking mode is supported through :meth:`~socket.setblocking`. A |
| 106 | generalization of this based on timeouts is supported through |
| 107 | :meth:`~socket.settimeout`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 108 | |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 109 | |
| 110 | Module contents |
| 111 | --------------- |
| 112 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 113 | The module :mod:`socket` exports the following constants and functions: |
| 114 | |
| 115 | |
| 116 | .. exception:: error |
| 117 | |
| 118 | .. index:: module: errno |
| 119 | |
Antoine Pitrou | 6120d87 | 2011-02-28 23:03:28 +0000 | [diff] [blame] | 120 | A subclass of :exc:`IOError`, this exception is raised for socket-related |
| 121 | errors. It is recommended that you inspect its ``errno`` attribute to |
| 122 | discriminate between different kinds of errors. |
| 123 | |
| 124 | .. seealso:: |
| 125 | The :mod:`errno` module contains symbolic names for the error codes |
| 126 | defined by the underlying operating system. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 127 | |
| 128 | |
| 129 | .. exception:: herror |
| 130 | |
Antoine Pitrou | 6120d87 | 2011-02-28 23:03:28 +0000 | [diff] [blame] | 131 | A subclass of :exc:`socket.error`, this exception is raised for |
| 132 | address-related errors, i.e. for functions that use *h_errno* in the POSIX |
| 133 | C API, including :func:`gethostbyname_ex` and :func:`gethostbyaddr`. |
| 134 | The accompanying value is a pair ``(h_errno, string)`` representing an |
| 135 | error returned by a library call. *h_errno* is a numeric value, while |
| 136 | *string* represents the description of *h_errno*, as returned by the |
| 137 | :c:func:`hstrerror` C function. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 138 | |
| 139 | |
| 140 | .. exception:: gaierror |
| 141 | |
Antoine Pitrou | 6120d87 | 2011-02-28 23:03:28 +0000 | [diff] [blame] | 142 | A subclass of :exc:`socket.error`, this exception is raised for |
| 143 | address-related errors by :func:`getaddrinfo` and :func:`getnameinfo`. |
| 144 | The accompanying value is a pair ``(error, string)`` representing an error |
| 145 | returned by a library call. *string* represents the description of |
| 146 | *error*, as returned by the :c:func:`gai_strerror` C function. The |
| 147 | numeric *error* value will match one of the :const:`EAI_\*` constants |
| 148 | defined in this module. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 149 | |
| 150 | |
| 151 | .. exception:: timeout |
| 152 | |
Antoine Pitrou | 6120d87 | 2011-02-28 23:03:28 +0000 | [diff] [blame] | 153 | A subclass of :exc:`socket.error`, this exception is raised when a timeout |
| 154 | occurs on a socket which has had timeouts enabled via a prior call to |
| 155 | :meth:`~socket.settimeout` (or implicitly through |
| 156 | :func:`~socket.setdefaulttimeout`). The accompanying value is a string |
| 157 | whose value is currently always "timed out". |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 158 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 159 | |
| 160 | .. data:: AF_UNIX |
| 161 | AF_INET |
| 162 | AF_INET6 |
| 163 | |
| 164 | These constants represent the address (and protocol) families, used for the |
| 165 | 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] | 166 | defined then this protocol is unsupported. More constants may be available |
| 167 | depending on the system. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 168 | |
| 169 | |
| 170 | .. data:: SOCK_STREAM |
| 171 | SOCK_DGRAM |
| 172 | SOCK_RAW |
| 173 | SOCK_RDM |
| 174 | SOCK_SEQPACKET |
| 175 | |
| 176 | These constants represent the socket types, used for the second argument to |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 177 | :func:`socket`. More constants may be available depending on the system. |
| 178 | (Only :const:`SOCK_STREAM` and :const:`SOCK_DGRAM` appear to be generally |
| 179 | useful.) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 180 | |
Antoine Pitrou | b1c5496 | 2010-10-14 15:05:38 +0000 | [diff] [blame] | 181 | .. data:: SOCK_CLOEXEC |
| 182 | SOCK_NONBLOCK |
| 183 | |
| 184 | These two constants, if defined, can be combined with the socket types and |
| 185 | allow you to set some flags atomically (thus avoiding possible race |
| 186 | conditions and the need for separate calls). |
| 187 | |
| 188 | .. seealso:: |
| 189 | |
| 190 | `Secure File Descriptor Handling <http://udrepper.livejournal.com/20407.html>`_ |
| 191 | for a more thorough explanation. |
| 192 | |
| 193 | Availability: Linux >= 2.6.27. |
| 194 | |
| 195 | .. versionadded:: 3.2 |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 196 | |
| 197 | .. data:: SO_* |
| 198 | SOMAXCONN |
| 199 | MSG_* |
| 200 | SOL_* |
| 201 | IPPROTO_* |
| 202 | IPPORT_* |
| 203 | INADDR_* |
| 204 | IP_* |
| 205 | IPV6_* |
| 206 | EAI_* |
| 207 | AI_* |
| 208 | NI_* |
| 209 | TCP_* |
| 210 | |
| 211 | Many constants of these forms, documented in the Unix documentation on sockets |
| 212 | and/or the IP protocol, are also defined in the socket module. They are |
| 213 | generally used in arguments to the :meth:`setsockopt` and :meth:`getsockopt` |
| 214 | methods of socket objects. In most cases, only those symbols that are defined |
| 215 | in the Unix header files are defined; for a few symbols, default values are |
| 216 | provided. |
| 217 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 218 | .. data:: SIO_* |
| 219 | RCVALL_* |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 220 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 221 | Constants for Windows' WSAIoctl(). The constants are used as arguments to the |
| 222 | :meth:`ioctl` method of socket objects. |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 223 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 224 | |
Christian Heimes | 043d6f6 | 2008-01-07 17:19:16 +0000 | [diff] [blame] | 225 | .. data:: TIPC_* |
| 226 | |
| 227 | TIPC related constants, matching the ones exported by the C socket API. See |
| 228 | the TIPC documentation for more information. |
| 229 | |
| 230 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 231 | .. data:: has_ipv6 |
| 232 | |
| 233 | This constant contains a boolean value which indicates if IPv6 is supported on |
| 234 | this platform. |
| 235 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 236 | |
Gregory P. Smith | b406637 | 2010-01-03 03:28:29 +0000 | [diff] [blame] | 237 | .. function:: create_connection(address[, timeout[, source_address]]) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 238 | |
Georg Brandl | f78e02b | 2008-06-10 17:40:04 +0000 | [diff] [blame] | 239 | Convenience function. Connect to *address* (a 2-tuple ``(host, port)``), |
| 240 | and return the socket object. Passing the optional *timeout* parameter will |
| 241 | set the timeout on the socket instance before attempting to connect. If no |
| 242 | *timeout* is supplied, the global default timeout setting returned by |
| 243 | :func:`getdefaulttimeout` is used. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 244 | |
Gregory P. Smith | b406637 | 2010-01-03 03:28:29 +0000 | [diff] [blame] | 245 | If supplied, *source_address* must be a 2-tuple ``(host, port)`` for the |
| 246 | socket to bind to as its source address before connecting. If host or port |
| 247 | are '' or 0 respectively the OS default behavior will be used. |
| 248 | |
| 249 | .. versionchanged:: 3.2 |
| 250 | *source_address* was added. |
| 251 | |
Giampaolo Rodolà | b383dbb | 2010-09-08 22:44:12 +0000 | [diff] [blame] | 252 | .. versionchanged:: 3.2 |
| 253 | support for the :keyword:`with` statement was added. |
| 254 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 255 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 256 | .. function:: getaddrinfo(host, port, family=0, type=0, proto=0, flags=0) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 257 | |
Antoine Pitrou | 9103597 | 2010-05-31 17:04:40 +0000 | [diff] [blame] | 258 | Translate the *host*/*port* argument into a sequence of 5-tuples that contain |
| 259 | all the necessary arguments for creating a socket connected to that service. |
| 260 | *host* is a domain name, a string representation of an IPv4/v6 address |
| 261 | or ``None``. *port* is a string service name such as ``'http'``, a numeric |
| 262 | port number or ``None``. By passing ``None`` as the value of *host* |
| 263 | and *port*, you can pass ``NULL`` to the underlying C API. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 264 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 265 | The *family*, *type* and *proto* arguments can be optionally specified |
Antoine Pitrou | 9103597 | 2010-05-31 17:04:40 +0000 | [diff] [blame] | 266 | in order to narrow the list of addresses returned. Passing zero as a |
| 267 | value for each of these arguments selects the full range of results. |
| 268 | The *flags* argument can be one or several of the ``AI_*`` constants, |
| 269 | and will influence how results are computed and returned. |
| 270 | For example, :const:`AI_NUMERICHOST` will disable domain name resolution |
| 271 | and will raise an error if *host* is a domain name. |
| 272 | |
| 273 | The function returns a list of 5-tuples with the following structure: |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 274 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 275 | ``(family, type, proto, canonname, sockaddr)`` |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 276 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 277 | In these tuples, *family*, *type*, *proto* are all integers and are |
Antoine Pitrou | 9103597 | 2010-05-31 17:04:40 +0000 | [diff] [blame] | 278 | meant to be passed to the :func:`socket` function. *canonname* will be |
| 279 | a string representing the canonical name of the *host* if |
| 280 | :const:`AI_CANONNAME` is part of the *flags* argument; else *canonname* |
| 281 | will be empty. *sockaddr* is a tuple describing a socket address, whose |
| 282 | format depends on the returned *family* (a ``(address, port)`` 2-tuple for |
| 283 | :const:`AF_INET`, a ``(address, port, flow info, scope id)`` 4-tuple for |
| 284 | :const:`AF_INET6`), and is meant to be passed to the :meth:`socket.connect` |
| 285 | method. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 286 | |
Antoine Pitrou | 9103597 | 2010-05-31 17:04:40 +0000 | [diff] [blame] | 287 | The following example fetches address information for a hypothetical TCP |
| 288 | connection to ``www.python.org`` on port 80 (results may differ on your |
| 289 | system if IPv6 isn't enabled):: |
| 290 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 291 | >>> socket.getaddrinfo("www.python.org", 80, proto=socket.SOL_TCP) |
Antoine Pitrou | 9103597 | 2010-05-31 17:04:40 +0000 | [diff] [blame] | 292 | [(2, 1, 6, '', ('82.94.164.162', 80)), |
| 293 | (10, 1, 6, '', ('2001:888:2000:d::a2', 80, 0, 0))] |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 294 | |
Giampaolo Rodolà | ccfb91c | 2010-08-17 15:30:23 +0000 | [diff] [blame] | 295 | .. versionchanged:: 3.2 |
| 296 | parameters can now be passed as single keyword arguments. |
| 297 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 298 | .. function:: getfqdn([name]) |
| 299 | |
| 300 | Return a fully qualified domain name for *name*. If *name* is omitted or empty, |
| 301 | 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] | 302 | hostname returned by :func:`gethostbyaddr` is checked, followed by aliases for the |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 303 | host, if available. The first name which includes a period is selected. In |
| 304 | case no fully qualified domain name is available, the hostname as returned by |
| 305 | :func:`gethostname` is returned. |
| 306 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 307 | |
| 308 | .. function:: gethostbyname(hostname) |
| 309 | |
| 310 | Translate a host name to IPv4 address format. The IPv4 address is returned as a |
| 311 | string, such as ``'100.50.200.5'``. If the host name is an IPv4 address itself |
| 312 | it is returned unchanged. See :func:`gethostbyname_ex` for a more complete |
| 313 | interface. :func:`gethostbyname` does not support IPv6 name resolution, and |
| 314 | :func:`getaddrinfo` should be used instead for IPv4/v6 dual stack support. |
| 315 | |
| 316 | |
| 317 | .. function:: gethostbyname_ex(hostname) |
| 318 | |
| 319 | Translate a host name to IPv4 address format, extended interface. Return a |
| 320 | triple ``(hostname, aliaslist, ipaddrlist)`` where *hostname* is the primary |
| 321 | host name responding to the given *ip_address*, *aliaslist* is a (possibly |
| 322 | empty) list of alternative host names for the same address, and *ipaddrlist* is |
| 323 | a list of IPv4 addresses for the same interface on the same host (often but not |
| 324 | always a single address). :func:`gethostbyname_ex` does not support IPv6 name |
| 325 | resolution, and :func:`getaddrinfo` should be used instead for IPv4/v6 dual |
| 326 | stack support. |
| 327 | |
| 328 | |
| 329 | .. function:: gethostname() |
| 330 | |
| 331 | Return a string containing the hostname of the machine where the Python |
Benjamin Peterson | 65676e4 | 2008-11-05 21:42:45 +0000 | [diff] [blame] | 332 | interpreter is currently executing. |
| 333 | |
| 334 | If you want to know the current machine's IP address, you may want to use |
| 335 | ``gethostbyname(gethostname())``. This operation assumes that there is a |
| 336 | valid address-to-host mapping for the host, and the assumption does not |
| 337 | always hold. |
| 338 | |
| 339 | Note: :func:`gethostname` doesn't always return the fully qualified domain |
| 340 | name; use ``getfqdn()`` (see above). |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 341 | |
| 342 | |
| 343 | .. function:: gethostbyaddr(ip_address) |
| 344 | |
| 345 | Return a triple ``(hostname, aliaslist, ipaddrlist)`` where *hostname* is the |
| 346 | primary host name responding to the given *ip_address*, *aliaslist* is a |
| 347 | (possibly empty) list of alternative host names for the same address, and |
| 348 | *ipaddrlist* is a list of IPv4/v6 addresses for the same interface on the same |
| 349 | host (most likely containing only a single address). To find the fully qualified |
| 350 | domain name, use the function :func:`getfqdn`. :func:`gethostbyaddr` supports |
| 351 | both IPv4 and IPv6. |
| 352 | |
| 353 | |
| 354 | .. function:: getnameinfo(sockaddr, flags) |
| 355 | |
| 356 | Translate a socket address *sockaddr* into a 2-tuple ``(host, port)``. Depending |
| 357 | on the settings of *flags*, the result can contain a fully-qualified domain name |
| 358 | or numeric address representation in *host*. Similarly, *port* can contain a |
| 359 | string port name or a numeric port number. |
| 360 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 361 | |
| 362 | .. function:: getprotobyname(protocolname) |
| 363 | |
| 364 | Translate an Internet protocol name (for example, ``'icmp'``) to a constant |
| 365 | suitable for passing as the (optional) third argument to the :func:`socket` |
| 366 | function. This is usually only needed for sockets opened in "raw" mode |
| 367 | (:const:`SOCK_RAW`); for the normal socket modes, the correct protocol is chosen |
| 368 | automatically if the protocol is omitted or zero. |
| 369 | |
| 370 | |
| 371 | .. function:: getservbyname(servicename[, protocolname]) |
| 372 | |
| 373 | Translate an Internet service name and protocol name to a port number for that |
| 374 | service. The optional protocol name, if given, should be ``'tcp'`` or |
| 375 | ``'udp'``, otherwise any protocol will match. |
| 376 | |
| 377 | |
| 378 | .. function:: getservbyport(port[, protocolname]) |
| 379 | |
| 380 | Translate an Internet port number and protocol name to a service name for that |
| 381 | service. The optional protocol name, if given, should be ``'tcp'`` or |
| 382 | ``'udp'``, otherwise any protocol will match. |
| 383 | |
| 384 | |
| 385 | .. function:: socket([family[, type[, proto]]]) |
| 386 | |
| 387 | Create a new socket using the given address family, socket type and protocol |
| 388 | number. The address family should be :const:`AF_INET` (the default), |
| 389 | :const:`AF_INET6` or :const:`AF_UNIX`. The socket type should be |
| 390 | :const:`SOCK_STREAM` (the default), :const:`SOCK_DGRAM` or perhaps one of the |
| 391 | other ``SOCK_`` constants. The protocol number is usually zero and may be |
| 392 | omitted in that case. |
| 393 | |
| 394 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 395 | .. function:: socketpair([family[, type[, proto]]]) |
| 396 | |
| 397 | Build a pair of connected socket objects using the given address family, socket |
| 398 | type, and protocol number. Address family, socket type, and protocol number are |
| 399 | as for the :func:`socket` function above. The default family is :const:`AF_UNIX` |
| 400 | if defined on the platform; otherwise, the default is :const:`AF_INET`. |
| 401 | Availability: Unix. |
| 402 | |
Antoine Pitrou | 9e0b864 | 2010-09-14 18:00:02 +0000 | [diff] [blame] | 403 | .. versionchanged:: 3.2 |
| 404 | The returned socket objects now support the whole socket API, rather |
| 405 | than a subset. |
| 406 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 407 | |
| 408 | .. function:: fromfd(fd, family, type[, proto]) |
| 409 | |
| 410 | Duplicate the file descriptor *fd* (an integer as returned by a file object's |
| 411 | :meth:`fileno` method) and build a socket object from the result. Address |
| 412 | family, socket type and protocol number are as for the :func:`socket` function |
| 413 | above. The file descriptor should refer to a socket, but this is not checked --- |
| 414 | subsequent operations on the object may fail if the file descriptor is invalid. |
| 415 | This function is rarely needed, but can be used to get or set socket options on |
| 416 | a socket passed to a program as standard input or output (such as a server |
| 417 | 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] | 418 | |
| 419 | |
| 420 | .. function:: ntohl(x) |
| 421 | |
| 422 | Convert 32-bit positive integers from network to host byte order. On machines |
| 423 | where the host byte order is the same as network byte order, this is a no-op; |
| 424 | otherwise, it performs a 4-byte swap operation. |
| 425 | |
| 426 | |
| 427 | .. function:: ntohs(x) |
| 428 | |
| 429 | Convert 16-bit positive integers from network to host byte order. On machines |
| 430 | where the host byte order is the same as network byte order, this is a no-op; |
| 431 | otherwise, it performs a 2-byte swap operation. |
| 432 | |
| 433 | |
| 434 | .. function:: htonl(x) |
| 435 | |
| 436 | Convert 32-bit positive integers from host to network byte order. On machines |
| 437 | where the host byte order is the same as network byte order, this is a no-op; |
| 438 | otherwise, it performs a 4-byte swap operation. |
| 439 | |
| 440 | |
| 441 | .. function:: htons(x) |
| 442 | |
| 443 | Convert 16-bit positive integers from host to network byte order. On machines |
| 444 | where the host byte order is the same as network byte order, this is a no-op; |
| 445 | otherwise, it performs a 2-byte swap operation. |
| 446 | |
| 447 | |
| 448 | .. function:: inet_aton(ip_string) |
| 449 | |
| 450 | Convert an IPv4 address from dotted-quad string format (for example, |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 451 | '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] | 452 | 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] | 453 | 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] | 454 | for the 32-bit packed binary this function returns. |
| 455 | |
Georg Brandl | f5123ef | 2009-06-04 10:28:36 +0000 | [diff] [blame] | 456 | :func:`inet_aton` also accepts strings with less than three dots; see the |
| 457 | Unix manual page :manpage:`inet(3)` for details. |
| 458 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 459 | If the IPv4 address string passed to this function is invalid, |
| 460 | :exc:`socket.error` will be raised. Note that exactly what is valid depends on |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 461 | the underlying C implementation of :c:func:`inet_aton`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 462 | |
Georg Brandl | 5f25972 | 2009-05-04 20:50:30 +0000 | [diff] [blame] | 463 | :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] | 464 | instead for IPv4/v6 dual stack support. |
| 465 | |
| 466 | |
| 467 | .. function:: inet_ntoa(packed_ip) |
| 468 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 469 | Convert a 32-bit packed IPv4 address (a bytes object four characters in |
| 470 | length) to its standard dotted-quad string representation (for example, |
| 471 | '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] | 472 | 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] | 473 | is the C type for the 32-bit packed binary data this function takes as an |
| 474 | argument. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 475 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 476 | If the byte sequence passed to this function is not exactly 4 bytes in |
| 477 | length, :exc:`socket.error` will be raised. :func:`inet_ntoa` does not |
Georg Brandl | 5f25972 | 2009-05-04 20:50:30 +0000 | [diff] [blame] | 478 | 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] | 479 | stack support. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 480 | |
| 481 | |
| 482 | .. function:: inet_pton(address_family, ip_string) |
| 483 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 484 | Convert an IP address from its family-specific string format to a packed, |
| 485 | 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] | 486 | calls for an object of type :c:type:`struct in_addr` (similar to |
| 487 | :func:`inet_aton`) or :c:type:`struct in6_addr`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 488 | |
| 489 | Supported values for *address_family* are currently :const:`AF_INET` and |
| 490 | :const:`AF_INET6`. If the IP address string *ip_string* is invalid, |
| 491 | :exc:`socket.error` will be raised. Note that exactly what is valid depends on |
| 492 | both the value of *address_family* and the underlying implementation of |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 493 | :c:func:`inet_pton`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 494 | |
| 495 | Availability: Unix (maybe not all platforms). |
| 496 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 497 | |
| 498 | .. function:: inet_ntop(address_family, packed_ip) |
| 499 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 500 | 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] | 501 | standard, family-specific string representation (for example, ``'7.10.0.5'`` or |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 502 | ``'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] | 503 | returns an object of type :c:type:`struct in_addr` (similar to :func:`inet_ntoa`) |
| 504 | or :c:type:`struct in6_addr`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 505 | |
| 506 | Supported values for *address_family* are currently :const:`AF_INET` and |
| 507 | :const:`AF_INET6`. If the string *packed_ip* is not the correct length for the |
| 508 | specified address family, :exc:`ValueError` will be raised. A |
| 509 | :exc:`socket.error` is raised for errors from the call to :func:`inet_ntop`. |
| 510 | |
| 511 | Availability: Unix (maybe not all platforms). |
| 512 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 513 | |
| 514 | .. function:: getdefaulttimeout() |
| 515 | |
| 516 | Return the default timeout in floating seconds for new socket objects. A value |
| 517 | of ``None`` indicates that new socket objects have no timeout. When the socket |
| 518 | module is first imported, the default is ``None``. |
| 519 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 520 | |
| 521 | .. function:: setdefaulttimeout(timeout) |
| 522 | |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 523 | Set the default timeout in floating seconds for new socket objects. When |
| 524 | the socket module is first imported, the default is ``None``. See |
| 525 | :meth:`~socket.settimeout` for possible values and their respective |
| 526 | meanings. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 527 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 528 | |
| 529 | .. data:: SocketType |
| 530 | |
| 531 | This is a Python type object that represents the socket object type. It is the |
| 532 | same as ``type(socket(...))``. |
| 533 | |
| 534 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 535 | .. _socket-objects: |
| 536 | |
| 537 | Socket Objects |
| 538 | -------------- |
| 539 | |
| 540 | Socket objects have the following methods. Except for :meth:`makefile` these |
| 541 | correspond to Unix system calls applicable to sockets. |
| 542 | |
| 543 | |
| 544 | .. method:: socket.accept() |
| 545 | |
| 546 | Accept a connection. The socket must be bound to an address and listening for |
| 547 | connections. The return value is a pair ``(conn, address)`` where *conn* is a |
| 548 | *new* socket object usable to send and receive data on the connection, and |
| 549 | *address* is the address bound to the socket on the other end of the connection. |
| 550 | |
| 551 | |
| 552 | .. method:: socket.bind(address) |
| 553 | |
| 554 | Bind the socket to *address*. The socket must not already be bound. (The format |
| 555 | of *address* depends on the address family --- see above.) |
| 556 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 557 | |
| 558 | .. method:: socket.close() |
| 559 | |
| 560 | Close the socket. All future operations on the socket object will fail. The |
| 561 | remote end will receive no more data (after queued data is flushed). Sockets are |
| 562 | automatically closed when they are garbage-collected. |
| 563 | |
Antoine Pitrou | 4a67a46 | 2011-01-02 22:06:53 +0000 | [diff] [blame] | 564 | .. note:: |
| 565 | :meth:`close()` releases the resource associated with a connection but |
| 566 | does not necessarily close the connection immediately. If you want |
| 567 | to close the connection in a timely fashion, call :meth:`shutdown()` |
| 568 | before :meth:`close()`. |
| 569 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 570 | |
| 571 | .. method:: socket.connect(address) |
| 572 | |
| 573 | Connect to a remote socket at *address*. (The format of *address* depends on the |
| 574 | address family --- see above.) |
| 575 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 576 | |
| 577 | .. method:: socket.connect_ex(address) |
| 578 | |
| 579 | Like ``connect(address)``, but return an error indicator instead of raising an |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 580 | 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] | 581 | problems, such as "host not found," can still raise exceptions). The error |
| 582 | indicator is ``0`` if the operation succeeded, otherwise the value of the |
Georg Brandl | 60203b4 | 2010-10-06 10:11:56 +0000 | [diff] [blame] | 583 | :c:data:`errno` variable. This is useful to support, for example, asynchronous |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 584 | connects. |
| 585 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 586 | |
Antoine Pitrou | 6e451df | 2010-08-09 20:39:54 +0000 | [diff] [blame] | 587 | .. method:: socket.detach() |
| 588 | |
| 589 | Put the socket object into closed state without actually closing the |
| 590 | underlying file descriptor. The file descriptor is returned, and can |
| 591 | be reused for other purposes. |
| 592 | |
| 593 | .. versionadded:: 3.2 |
| 594 | |
| 595 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 596 | .. method:: socket.fileno() |
| 597 | |
| 598 | Return the socket's file descriptor (a small integer). This is useful with |
| 599 | :func:`select.select`. |
| 600 | |
| 601 | Under Windows the small integer returned by this method cannot be used where a |
| 602 | file descriptor can be used (such as :func:`os.fdopen`). Unix does not have |
| 603 | this limitation. |
| 604 | |
| 605 | |
| 606 | .. method:: socket.getpeername() |
| 607 | |
| 608 | Return the remote address to which the socket is connected. This is useful to |
| 609 | find out the port number of a remote IPv4/v6 socket, for instance. (The format |
| 610 | of the address returned depends on the address family --- see above.) On some |
| 611 | systems this function is not supported. |
| 612 | |
| 613 | |
| 614 | .. method:: socket.getsockname() |
| 615 | |
| 616 | Return the socket's own address. This is useful to find out the port number of |
| 617 | an IPv4/v6 socket, for instance. (The format of the address returned depends on |
| 618 | the address family --- see above.) |
| 619 | |
| 620 | |
| 621 | .. method:: socket.getsockopt(level, optname[, buflen]) |
| 622 | |
| 623 | Return the value of the given socket option (see the Unix man page |
| 624 | :manpage:`getsockopt(2)`). The needed symbolic constants (:const:`SO_\*` etc.) |
| 625 | are defined in this module. If *buflen* is absent, an integer option is assumed |
| 626 | and its integer value is returned by the function. If *buflen* is present, it |
| 627 | 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] | 628 | 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] | 629 | 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] | 630 | to decode C structures encoded as byte strings). |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 631 | |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 632 | |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 633 | .. method:: socket.gettimeout() |
| 634 | |
| 635 | Return the timeout in floating seconds associated with socket operations, |
| 636 | or ``None`` if no timeout is set. This reflects the last call to |
| 637 | :meth:`setblocking` or :meth:`settimeout`. |
| 638 | |
| 639 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 640 | .. method:: socket.ioctl(control, option) |
| 641 | |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 642 | :platform: Windows |
| 643 | |
Christian Heimes | 679db4a | 2008-01-18 09:56:22 +0000 | [diff] [blame] | 644 | The :meth:`ioctl` method is a limited interface to the WSAIoctl system |
Georg Brandl | 8569e58 | 2010-05-19 20:57:08 +0000 | [diff] [blame] | 645 | interface. Please refer to the `Win32 documentation |
| 646 | <http://msdn.microsoft.com/en-us/library/ms741621%28VS.85%29.aspx>`_ for more |
| 647 | information. |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 648 | |
Alexandre Vassalotti | 6d3dfc3 | 2009-07-29 19:54:39 +0000 | [diff] [blame] | 649 | On other platforms, the generic :func:`fcntl.fcntl` and :func:`fcntl.ioctl` |
| 650 | 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] | 651 | |
| 652 | .. method:: socket.listen(backlog) |
| 653 | |
| 654 | Listen for connections made to the socket. The *backlog* argument specifies the |
Antoine Pitrou | 1be815a | 2011-05-10 19:16:29 +0200 | [diff] [blame] | 655 | maximum number of queued connections and should be at least 0; the maximum value |
| 656 | is system-dependent (usually 5), the minimum value is forced to 0. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 657 | |
| 658 | |
Georg Brandl | e9e8c9b | 2010-12-28 11:49:41 +0000 | [diff] [blame] | 659 | .. method:: socket.makefile(mode='r', buffering=None, *, encoding=None, \ |
| 660 | errors=None, newline=None) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 661 | |
| 662 | .. index:: single: I/O control; buffering |
| 663 | |
Georg Brandl | e9e8c9b | 2010-12-28 11:49:41 +0000 | [diff] [blame] | 664 | Return a :term:`file object` associated with the socket. The exact returned |
| 665 | type depends on the arguments given to :meth:`makefile`. These arguments are |
| 666 | interpreted the same way as by the built-in :func:`open` function. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 667 | |
Georg Brandl | e9e8c9b | 2010-12-28 11:49:41 +0000 | [diff] [blame] | 668 | 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] | 669 | references to the socket. The socket must be in blocking mode; it can have |
| 670 | a timeout, but the file object's internal buffer may end up in a inconsistent |
| 671 | state if a timeout occurs. |
Georg Brandl | e9e8c9b | 2010-12-28 11:49:41 +0000 | [diff] [blame] | 672 | |
| 673 | .. note:: |
| 674 | |
| 675 | On Windows, the file-like object created by :meth:`makefile` cannot be |
| 676 | used where a file object with a file descriptor is expected, such as the |
| 677 | stream arguments of :meth:`subprocess.Popen`. |
Antoine Pitrou | 4adb288 | 2010-01-04 18:50:53 +0000 | [diff] [blame] | 678 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 679 | |
| 680 | .. method:: socket.recv(bufsize[, flags]) |
| 681 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 682 | 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] | 683 | data received. The maximum amount of data to be received at once is specified |
| 684 | by *bufsize*. See the Unix manual page :manpage:`recv(2)` for the meaning of |
| 685 | the optional argument *flags*; it defaults to zero. |
| 686 | |
| 687 | .. note:: |
| 688 | |
| 689 | For best match with hardware and network realities, the value of *bufsize* |
| 690 | should be a relatively small power of 2, for example, 4096. |
| 691 | |
| 692 | |
| 693 | .. method:: socket.recvfrom(bufsize[, flags]) |
| 694 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 695 | Receive data from the socket. The return value is a pair ``(bytes, address)`` |
| 696 | 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] | 697 | address of the socket sending the data. See the Unix manual page |
| 698 | :manpage:`recv(2)` for the meaning of the optional argument *flags*; it defaults |
| 699 | to zero. (The format of *address* depends on the address family --- see above.) |
| 700 | |
| 701 | |
| 702 | .. method:: socket.recvfrom_into(buffer[, nbytes[, flags]]) |
| 703 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 704 | Receive data from the socket, writing it into *buffer* instead of creating a |
| 705 | 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] | 706 | the number of bytes received and *address* is the address of the socket sending |
| 707 | the data. See the Unix manual page :manpage:`recv(2)` for the meaning of the |
| 708 | optional argument *flags*; it defaults to zero. (The format of *address* |
| 709 | depends on the address family --- see above.) |
| 710 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 711 | |
| 712 | .. method:: socket.recv_into(buffer[, nbytes[, flags]]) |
| 713 | |
| 714 | 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] | 715 | 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] | 716 | receive up to the size available in the given buffer. Returns the number of |
| 717 | bytes received. See the Unix manual page :manpage:`recv(2)` for the meaning |
| 718 | of the optional argument *flags*; it defaults to zero. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 719 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 720 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 721 | .. method:: socket.send(bytes[, flags]) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 722 | |
| 723 | Send data to the socket. The socket must be connected to a remote socket. The |
| 724 | optional *flags* argument has the same meaning as for :meth:`recv` above. |
| 725 | Returns the number of bytes sent. Applications are responsible for checking that |
| 726 | all data has been sent; if only some of the data was transmitted, the |
| 727 | application needs to attempt delivery of the remaining data. |
| 728 | |
| 729 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 730 | .. method:: socket.sendall(bytes[, flags]) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 731 | |
| 732 | Send data to the socket. The socket must be connected to a remote socket. The |
| 733 | optional *flags* argument has the same meaning as for :meth:`recv` above. |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 734 | Unlike :meth:`send`, this method continues to send data from *bytes* until |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 735 | either all data has been sent or an error occurs. ``None`` is returned on |
| 736 | success. On error, an exception is raised, and there is no way to determine how |
| 737 | much data, if any, was successfully sent. |
| 738 | |
| 739 | |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 740 | .. method:: socket.sendto(bytes[, flags], address) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 741 | |
| 742 | Send data to the socket. The socket should not be connected to a remote socket, |
| 743 | since the destination socket is specified by *address*. The optional *flags* |
| 744 | argument has the same meaning as for :meth:`recv` above. Return the number of |
| 745 | bytes sent. (The format of *address* depends on the address family --- see |
| 746 | above.) |
| 747 | |
| 748 | |
| 749 | .. method:: socket.setblocking(flag) |
| 750 | |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 751 | Set blocking or non-blocking mode of the socket: if *flag* is false, the |
| 752 | socket is set to non-blocking, else to blocking mode. |
| 753 | |
| 754 | This method is a shorthand for certain :meth:`~socket.settimeout` calls: |
| 755 | |
| 756 | * ``sock.setblocking(True)`` is equivalent to ``sock.settimeout(None)`` |
| 757 | |
| 758 | * ``sock.setblocking(False)`` is equivalent to ``sock.settimeout(0.0)`` |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 759 | |
| 760 | |
| 761 | .. method:: socket.settimeout(value) |
| 762 | |
| 763 | 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] | 764 | nonnegative floating point number expressing seconds, or ``None``. |
| 765 | If a non-zero value is given, subsequent socket operations will raise a |
| 766 | :exc:`timeout` exception if the timeout period *value* has elapsed before |
| 767 | the operation has completed. If zero is given, the socket is put in |
| 768 | 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] | 769 | |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 770 | 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] | 771 | |
| 772 | |
| 773 | .. method:: socket.setsockopt(level, optname, value) |
| 774 | |
| 775 | .. index:: module: struct |
| 776 | |
| 777 | Set the value of the given socket option (see the Unix manual page |
| 778 | :manpage:`setsockopt(2)`). The needed symbolic constants are defined in the |
| 779 | :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] | 780 | bytes object representing a buffer. In the latter case it is up to the caller to |
| 781 | ensure that the bytestring contains the proper bits (see the optional built-in |
| 782 | module :mod:`struct` for a way to encode C structures as bytestrings). |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 783 | |
| 784 | |
| 785 | .. method:: socket.shutdown(how) |
| 786 | |
| 787 | Shut down one or both halves of the connection. If *how* is :const:`SHUT_RD`, |
| 788 | further receives are disallowed. If *how* is :const:`SHUT_WR`, further sends |
| 789 | are disallowed. If *how* is :const:`SHUT_RDWR`, further sends and receives are |
Georg Brandl | 0104bcd | 2010-07-11 09:23:11 +0000 | [diff] [blame] | 790 | disallowed. Depending on the platform, shutting down one half of the connection |
| 791 | can also close the opposite half (e.g. on Mac OS X, ``shutdown(SHUT_WR)`` does |
| 792 | not allow further reads on the other end of the connection). |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 793 | |
Georg Brandl | 8569e58 | 2010-05-19 20:57:08 +0000 | [diff] [blame] | 794 | Note that there are no methods :meth:`read` or :meth:`write`; use |
| 795 | :meth:`~socket.recv` and :meth:`~socket.send` without *flags* argument instead. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 796 | |
| 797 | Socket objects also have these (read-only) attributes that correspond to the |
| 798 | values given to the :class:`socket` constructor. |
| 799 | |
| 800 | |
| 801 | .. attribute:: socket.family |
| 802 | |
| 803 | The socket family. |
| 804 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 805 | |
| 806 | .. attribute:: socket.type |
| 807 | |
| 808 | The socket type. |
| 809 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 810 | |
| 811 | .. attribute:: socket.proto |
| 812 | |
| 813 | The socket protocol. |
| 814 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 815 | |
Antoine Pitrou | dfad7e3 | 2011-01-05 21:17:36 +0000 | [diff] [blame] | 816 | |
| 817 | .. _socket-timeouts: |
| 818 | |
| 819 | Notes on socket timeouts |
| 820 | ------------------------ |
| 821 | |
| 822 | A socket object can be in one of three modes: blocking, non-blocking, or |
| 823 | timeout. Sockets are by default always created in blocking mode, but this |
| 824 | can be changed by calling :func:`setdefaulttimeout`. |
| 825 | |
| 826 | * In *blocking mode*, operations block until complete or the system returns |
| 827 | an error (such as connection timed out). |
| 828 | |
| 829 | * In *non-blocking mode*, operations fail (with an error that is unfortunately |
| 830 | system-dependent) if they cannot be completed immediately: functions from the |
| 831 | :mod:`select` can be used to know when and whether a socket is available for |
| 832 | reading or writing. |
| 833 | |
| 834 | * In *timeout mode*, operations fail if they cannot be completed within the |
| 835 | timeout specified for the socket (they raise a :exc:`timeout` exception) |
| 836 | or if the system returns an error. |
| 837 | |
| 838 | .. note:: |
| 839 | At the operating system level, sockets in *timeout mode* are internally set |
| 840 | in non-blocking mode. Also, the blocking and timeout modes are shared between |
| 841 | file descriptors and socket objects that refer to the same network endpoint. |
| 842 | This implementation detail can have visible consequences if e.g. you decide |
| 843 | to use the :meth:`~socket.fileno()` of a socket. |
| 844 | |
| 845 | Timeouts and the ``connect`` method |
| 846 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| 847 | |
| 848 | The :meth:`~socket.connect` operation is also subject to the timeout |
| 849 | setting, and in general it is recommended to call :meth:`~socket.settimeout` |
| 850 | before calling :meth:`~socket.connect` or pass a timeout parameter to |
| 851 | :meth:`create_connection`. However, the system network stack may also |
| 852 | return a connection timeout error of its own regardless of any Python socket |
| 853 | timeout setting. |
| 854 | |
| 855 | Timeouts and the ``accept`` method |
| 856 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| 857 | |
| 858 | If :func:`getdefaulttimeout` is not :const:`None`, sockets returned by |
| 859 | the :meth:`~socket.accept` method inherit that timeout. Otherwise, the |
| 860 | behaviour depends on settings of the listening socket: |
| 861 | |
| 862 | * if the listening socket is in *blocking mode* or in *timeout mode*, |
| 863 | the socket returned by :meth:`~socket.accept` is in *blocking mode*; |
| 864 | |
| 865 | * if the listening socket is in *non-blocking mode*, whether the socket |
| 866 | returned by :meth:`~socket.accept` is in blocking or non-blocking mode |
| 867 | is operating system-dependent. If you want to ensure cross-platform |
| 868 | behaviour, it is recommended you manually override this setting. |
| 869 | |
| 870 | |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 871 | .. _socket-example: |
| 872 | |
| 873 | Example |
| 874 | ------- |
| 875 | |
| 876 | Here are four minimal example programs using the TCP/IP protocol: a server that |
| 877 | echoes all data that it receives back (servicing only one client), and a client |
| 878 | using it. Note that a server must perform the sequence :func:`socket`, |
Georg Brandl | 8569e58 | 2010-05-19 20:57:08 +0000 | [diff] [blame] | 879 | :meth:`~socket.bind`, :meth:`~socket.listen`, :meth:`~socket.accept` (possibly |
| 880 | repeating the :meth:`~socket.accept` to service more than one client), while a |
| 881 | client only needs the sequence :func:`socket`, :meth:`~socket.connect`. Also |
| 882 | note that the server does not :meth:`~socket.send`/:meth:`~socket.recv` on the |
| 883 | socket it is listening on but on the new socket returned by |
| 884 | :meth:`~socket.accept`. |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 885 | |
| 886 | The first two examples support IPv4 only. :: |
| 887 | |
| 888 | # Echo server program |
| 889 | import socket |
| 890 | |
Christian Heimes | 81ee3ef | 2008-05-04 22:42:01 +0000 | [diff] [blame] | 891 | HOST = '' # Symbolic name meaning all available interfaces |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 892 | PORT = 50007 # Arbitrary non-privileged port |
| 893 | s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) |
| 894 | s.bind((HOST, PORT)) |
| 895 | s.listen(1) |
| 896 | conn, addr = s.accept() |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 897 | print('Connected by', addr) |
Collin Winter | 4633448 | 2007-09-10 00:49:57 +0000 | [diff] [blame] | 898 | while True: |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 899 | data = conn.recv(1024) |
| 900 | if not data: break |
| 901 | conn.send(data) |
| 902 | conn.close() |
| 903 | |
| 904 | :: |
| 905 | |
| 906 | # Echo client program |
| 907 | import socket |
| 908 | |
| 909 | HOST = 'daring.cwi.nl' # The remote host |
| 910 | PORT = 50007 # The same port as used by the server |
| 911 | s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) |
| 912 | s.connect((HOST, PORT)) |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 913 | s.send(b'Hello, world') |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 914 | data = s.recv(1024) |
| 915 | s.close() |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 916 | print('Received', repr(data)) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 917 | |
| 918 | The next two examples are identical to the above two, but support both IPv4 and |
| 919 | IPv6. The server side will listen to the first address family available (it |
| 920 | should listen to both instead). On most of IPv6-ready systems, IPv6 will take |
| 921 | precedence and the server may not accept IPv4 traffic. The client side will try |
| 922 | to connect to the all addresses returned as a result of the name resolution, and |
| 923 | sends traffic to the first one connected successfully. :: |
| 924 | |
| 925 | # Echo server program |
| 926 | import socket |
| 927 | import sys |
| 928 | |
Alexandre Vassalotti | 5f8ced2 | 2008-05-16 00:03:33 +0000 | [diff] [blame] | 929 | HOST = None # Symbolic name meaning all available interfaces |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 930 | PORT = 50007 # Arbitrary non-privileged port |
| 931 | s = None |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 932 | for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC, |
| 933 | socket.SOCK_STREAM, 0, socket.AI_PASSIVE): |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 934 | af, socktype, proto, canonname, sa = res |
| 935 | try: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 936 | s = socket.socket(af, socktype, proto) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 937 | except socket.error as msg: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 938 | s = None |
| 939 | continue |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 940 | try: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 941 | s.bind(sa) |
| 942 | s.listen(1) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 943 | except socket.error as msg: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 944 | s.close() |
| 945 | s = None |
| 946 | continue |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 947 | break |
| 948 | if s is None: |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 949 | print('could not open socket') |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 950 | sys.exit(1) |
| 951 | conn, addr = s.accept() |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 952 | print('Connected by', addr) |
Collin Winter | 4633448 | 2007-09-10 00:49:57 +0000 | [diff] [blame] | 953 | while True: |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 954 | data = conn.recv(1024) |
| 955 | if not data: break |
| 956 | conn.send(data) |
| 957 | conn.close() |
| 958 | |
| 959 | :: |
| 960 | |
| 961 | # Echo client program |
| 962 | import socket |
| 963 | import sys |
| 964 | |
| 965 | HOST = 'daring.cwi.nl' # The remote host |
| 966 | PORT = 50007 # The same port as used by the server |
| 967 | s = None |
| 968 | for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC, socket.SOCK_STREAM): |
| 969 | af, socktype, proto, canonname, sa = res |
| 970 | try: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 971 | s = socket.socket(af, socktype, proto) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 972 | except socket.error as msg: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 973 | s = None |
| 974 | continue |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 975 | try: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 976 | s.connect(sa) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 977 | except socket.error as msg: |
Georg Brandl | a1c6a1c | 2009-01-03 21:26:05 +0000 | [diff] [blame] | 978 | s.close() |
| 979 | s = None |
| 980 | continue |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 981 | break |
| 982 | if s is None: |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 983 | print('could not open socket') |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 984 | sys.exit(1) |
Georg Brandl | 42b2f2e | 2008-08-14 11:50:32 +0000 | [diff] [blame] | 985 | s.send(b'Hello, world') |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 986 | data = s.recv(1024) |
| 987 | s.close() |
Georg Brandl | 6911e3c | 2007-09-04 07:15:32 +0000 | [diff] [blame] | 988 | print('Received', repr(data)) |
Georg Brandl | 116aa62 | 2007-08-15 14:28:22 +0000 | [diff] [blame] | 989 | |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 990 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 991 | The last example shows how to write a very simple network sniffer with raw |
Alexandre Vassalotti | 5f8ced2 | 2008-05-16 00:03:33 +0000 | [diff] [blame] | 992 | sockets on Windows. The example requires administrator privileges to modify |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 993 | the interface:: |
| 994 | |
| 995 | import socket |
| 996 | |
| 997 | # the public network interface |
| 998 | HOST = socket.gethostbyname(socket.gethostname()) |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 999 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1000 | # create a raw socket and bind it to the public interface |
| 1001 | s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_IP) |
| 1002 | s.bind((HOST, 0)) |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1003 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1004 | # Include IP headers |
| 1005 | s.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1) |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1006 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1007 | # receive all packages |
| 1008 | s.ioctl(socket.SIO_RCVALL, socket.RCVALL_ON) |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1009 | |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1010 | # receive a package |
Neal Norwitz | 752abd0 | 2008-05-13 04:55:24 +0000 | [diff] [blame] | 1011 | print(s.recvfrom(65565)) |
Georg Brandl | 48310cd | 2009-01-03 21:18:54 +0000 | [diff] [blame] | 1012 | |
Christian Heimes | c3f30c4 | 2008-02-22 16:37:40 +0000 | [diff] [blame] | 1013 | # disabled promiscuous mode |
Christian Heimes | faf2f63 | 2008-01-06 16:59:19 +0000 | [diff] [blame] | 1014 | s.ioctl(socket.SIO_RCVALL, socket.RCVALL_OFF) |
Antoine Pitrou | 7bdfe77 | 2010-12-12 20:57:12 +0000 | [diff] [blame] | 1015 | |
| 1016 | |
| 1017 | .. seealso:: |
| 1018 | |
| 1019 | For an introduction to socket programming (in C), see the following papers: |
| 1020 | |
| 1021 | - *An Introductory 4.3BSD Interprocess Communication Tutorial*, by Stuart Sechrest |
| 1022 | |
| 1023 | - *An Advanced 4.3BSD Interprocess Communication Tutorial*, by Samuel J. Leffler et |
| 1024 | al, |
| 1025 | |
| 1026 | both in the UNIX Programmer's Manual, Supplementary Documents 1 (sections |
| 1027 | PS1:7 and PS1:8). The platform-specific reference material for the various |
| 1028 | socket-related system calls are also a valuable source of information on the |
| 1029 | details of socket semantics. For Unix, refer to the manual pages; for Windows, |
| 1030 | see the WinSock (or Winsock 2) specification. For IPv6-ready APIs, readers may |
| 1031 | want to refer to :rfc:`3493` titled Basic Socket Interface Extensions for IPv6. |
| 1032 | |