Revert socket.rst to unix-eol.

1 files changed, 906 insertions, 906 deletions

diff --git a/Doc/library/socket.rst b/Doc/library/socket.rst
index 1eb183e..40e6d19 100644
--- a/Doc/library/socket.rst
+++ b/Doc/library/socket.rst
@@ -1,906 +1,906 @@
-

-:mod:`socket` --- Low-level networking interface

-================================================

-

-.. module:: socket

-   :synopsis: Low-level networking interface.

-

-

-This module provides access to the BSD *socket* interface. It is available on

-all modern Unix systems, Windows, Mac OS X, BeOS, OS/2, and probably additional

-platforms.

-

-.. note::

-

-   Some behavior may be platform dependent, since calls are made to the operating

-   system socket APIs.

-

-For an introduction to socket programming (in C), see the following papers: An

-Introductory 4.3BSD Interprocess Communication Tutorial, by Stuart Sechrest and

-An Advanced 4.3BSD Interprocess Communication Tutorial, by Samuel J.  Leffler et

-al, both in the UNIX Programmer's Manual, Supplementary Documents 1 (sections

-PS1:7 and PS1:8).  The platform-specific reference material for the various

-socket-related system calls are also a valuable source of information on the

-details of socket semantics.  For Unix, refer to the manual pages; for Windows,

-see the WinSock (or Winsock 2) specification. For IPv6-ready APIs, readers may

-want to refer to :rfc:`2553` titled Basic Socket Interface Extensions for IPv6.

-

-.. index:: object: socket

-

-The Python interface is a straightforward transliteration of the Unix system

-call and library interface for sockets to Python's object-oriented style: the

-:func:`socket` function returns a :dfn:`socket object` whose methods implement

-the various socket system calls.  Parameter types are somewhat higher-level than

-in the C interface: as with :meth:`read` and :meth:`write` operations on Python

-files, buffer allocation on receive operations is automatic, and buffer length

-is implicit on send operations.

-

-Socket addresses are represented as follows: A single string is used for the

-:const:`AF_UNIX` address family. A pair ``(host, port)`` is used for the

-:const:`AF_INET` address family, where *host* is a string representing either a

-hostname in Internet domain notation like ``'daring.cwi.nl'`` or an IPv4 address

-like ``'100.50.200.5'``, and *port* is an integral port number. For

-:const:`AF_INET6` address family, a four-tuple ``(host, port, flowinfo,

-scopeid)`` is used, where *flowinfo* and *scopeid* represents ``sin6_flowinfo``

-and ``sin6_scope_id`` member in :const:`struct sockaddr_in6` in C. For

-:mod:`socket` module methods, *flowinfo* and *scopeid* can be omitted just for

-backward compatibility. Note, however, omission of *scopeid* can cause problems

-in manipulating scoped IPv6 addresses. Other address families are currently not

-supported. The address format required by a particular socket object is

-automatically selected based on the address family specified when the socket

-object was created.

-

-For IPv4 addresses, two special forms are accepted instead of a host address:

-the empty string represents :const:`INADDR_ANY`, and the string

-``'<broadcast>'`` represents :const:`INADDR_BROADCAST`. The behavior is not

-available for IPv6 for backward compatibility, therefore, you may want to avoid

-these if you intend to support IPv6 with your Python programs.

-

-If you use a hostname in the *host* portion of IPv4/v6 socket address, the

-program may show a nondeterministic behavior, as Python uses the first address

-returned from the DNS resolution.  The socket address will be resolved

-differently into an actual IPv4/v6 address, depending on the results from DNS

-resolution and/or the host configuration.  For deterministic behavior use a

-numeric address in *host* portion.

-

-.. versionadded:: 2.5

-   AF_NETLINK sockets are represented as  pairs ``pid, groups``.

-

-All errors raise exceptions.  The normal exceptions for invalid argument types

-and out-of-memory conditions can be raised; errors related to socket or address

-semantics raise the error :exc:`socket.error`.

-

-Non-blocking mode is supported through :meth:`setblocking`.  A generalization of

-this based on timeouts is supported through :meth:`settimeout`.

-

-The module :mod:`socket` exports the following constants and functions:

-

-

-.. exception:: error

-

-   .. index:: module: errno

-

-   This exception is raised for socket-related errors. The accompanying value is

-   either a string telling what went wrong or a pair ``(errno, string)``

-   representing an error returned by a system call, similar to the value

-   accompanying :exc:`os.error`. See the module :mod:`errno`, which contains names

-   for the error codes defined by the underlying operating system.

-

-   .. versionchanged:: 2.6

-      :exc:`socket.error` is now a child class of :exc:`IOError`.

-

-

-.. exception:: herror

-

-   This exception is raised for address-related errors, i.e. for functions that use

-   *h_errno* in the C API, including :func:`gethostbyname_ex` and

-   :func:`gethostbyaddr`.

-

-   The accompanying value is a pair ``(h_errno, string)`` representing an error

-   returned by a library call. *string* represents the description of *h_errno*, as

-   returned by the :cfunc:`hstrerror` C function.

-

-

-.. exception:: gaierror

-

-   This exception is raised for address-related errors, for :func:`getaddrinfo` and

-   :func:`getnameinfo`. The accompanying value is a pair ``(error, string)``

-   representing an error returned by a library call. *string* represents the

-   description of *error*, as returned by the :cfunc:`gai_strerror` C function. The

-   *error* value will match one of the :const:`EAI_\*` constants defined in this

-   module.

-

-

-.. exception:: timeout

-

-   This exception is raised when a timeout occurs on a socket which has had

-   timeouts enabled via a prior call to :meth:`settimeout`.  The accompanying value

-   is a string whose value is currently always "timed out".

-

-   .. versionadded:: 2.3

-

-

-.. data:: AF_UNIX

-          AF_INET

-          AF_INET6

-

-   These constants represent the address (and protocol) families, used for the

-   first argument to :func:`socket`.  If the :const:`AF_UNIX` constant is not

-   defined then this protocol is unsupported.

-

-

-.. data:: SOCK_STREAM

-          SOCK_DGRAM

-          SOCK_RAW

-          SOCK_RDM

-          SOCK_SEQPACKET

-

-   These constants represent the socket types, used for the second argument to

-   :func:`socket`. (Only :const:`SOCK_STREAM` and :const:`SOCK_DGRAM` appear to be

-   generally useful.)

-

-

-.. data:: SO_*

-          SOMAXCONN

-          MSG_*

-          SOL_*

-          IPPROTO_*

-          IPPORT_*

-          INADDR_*

-          IP_*

-          IPV6_*

-          EAI_*

-          AI_*

-          NI_*

-          TCP_*

-

-   Many constants of these forms, documented in the Unix documentation on sockets

-   and/or the IP protocol, are also defined in the socket module. They are

-   generally used in arguments to the :meth:`setsockopt` and :meth:`getsockopt`

-   methods of socket objects.  In most cases, only those symbols that are defined

-   in the Unix header files are defined; for a few symbols, default values are

-   provided.

-

-.. data:: SIO_*

-          RCVALL_*

-          

-   Constants for Windows' WSAIoctl(). The constants are used as arguments to the

-   :meth:`ioctl` method of socket objects.

-   

-   .. versionadded:: 2.6

-

-

-.. data:: has_ipv6

-

-   This constant contains a boolean value which indicates if IPv6 is supported on

-   this platform.

-

-   .. versionadded:: 2.3

-

-

-.. function:: create_connection(address[, timeout])

-

-   Connects to the *address* received (as usual, a ``(host, port)`` pair), with an

-   optional timeout for the connection.  Especially useful for higher-level

-   protocols, it is not normally used directly from application-level code.

-   Passing the optional *timeout* parameter will set the timeout on the socket

-   instance (if it is not given or ``None``, the global default timeout setting is

-   used).

-

-   .. versionadded:: 2.6

-

-

-.. function:: getaddrinfo(host, port[, family[, socktype[, proto[, flags]]]])

-

-   Resolves the *host*/*port* argument, into a sequence of 5-tuples that contain

-   all the necessary argument for the sockets manipulation. *host* is a domain

-   name, a string representation of IPv4/v6 address or ``None``. *port* is a string

-   service name (like ``'http'``), a numeric port number or ``None``.

-

-   The rest of the arguments are optional and must be numeric if specified.  For

-   *host* and *port*, by passing either an empty string or ``None``, you can pass

-   ``NULL`` to the C API.  The :func:`getaddrinfo` function returns a list of

-   5-tuples with the following structure:

-

-   ``(family, socktype, proto, canonname, sockaddr)``

-

-   *family*, *socktype*, *proto* are all integer and are meant to be passed to the

-   :func:`socket` function. *canonname* is a string representing the canonical name

-   of the *host*. It can be a numeric IPv4/v6 address when :const:`AI_CANONNAME` is

-   specified for a numeric *host*. *sockaddr* is a tuple describing a socket

-   address, as described above. See the source for :mod:`socket` and other

-   library modules for a typical usage of the function.

-

-   .. versionadded:: 2.2

-

-

-.. function:: getfqdn([name])

-

-   Return a fully qualified domain name for *name*. If *name* is omitted or empty,

-   it is interpreted as the local host.  To find the fully qualified name, the

-   hostname returned by :func:`gethostbyaddr` is checked, then aliases for the

-   host, if available.  The first name which includes a period is selected.  In

-   case no fully qualified domain name is available, the hostname as returned by

-   :func:`gethostname` is returned.

-

-   .. versionadded:: 2.0

-

-

-.. function:: gethostbyname(hostname)

-

-   Translate a host name to IPv4 address format.  The IPv4 address is returned as a

-   string, such as  ``'100.50.200.5'``.  If the host name is an IPv4 address itself

-   it is returned unchanged.  See :func:`gethostbyname_ex` for a more complete

-   interface. :func:`gethostbyname` does not support IPv6 name resolution, and

-   :func:`getaddrinfo` should be used instead for IPv4/v6 dual stack support.

-

-

-.. function:: gethostbyname_ex(hostname)

-

-   Translate a host name to IPv4 address format, extended interface. Return a

-   triple ``(hostname, aliaslist, ipaddrlist)`` where *hostname* is the primary

-   host name responding to the given *ip_address*, *aliaslist* is a (possibly

-   empty) list of alternative host names for the same address, and *ipaddrlist* is

-   a list of IPv4 addresses for the same interface on the same host (often but not

-   always a single address). :func:`gethostbyname_ex` does not support IPv6 name

-   resolution, and :func:`getaddrinfo` should be used instead for IPv4/v6 dual

-   stack support.

-

-

-.. function:: gethostname()

-

-   Return a string containing the hostname of the machine where  the Python

-   interpreter is currently executing. If you want to know the current machine's IP

-   address, you may want to use ``gethostbyname(gethostname())``. This operation

-   assumes that there is a valid address-to-host mapping for the host, and the

-   assumption does not always hold. Note: :func:`gethostname` doesn't always return

-   the fully qualified domain name; use ``getfqdn()`` (see above).

-

-

-.. function:: gethostbyaddr(ip_address)

-

-   Return a triple ``(hostname, aliaslist, ipaddrlist)`` where *hostname* is the

-   primary host name responding to the given *ip_address*, *aliaslist* is a

-   (possibly empty) list of alternative host names for the same address, and

-   *ipaddrlist* is a list of IPv4/v6 addresses for the same interface on the same

-   host (most likely containing only a single address). To find the fully qualified

-   domain name, use the function :func:`getfqdn`. :func:`gethostbyaddr` supports

-   both IPv4 and IPv6.

-

-

-.. function:: getnameinfo(sockaddr, flags)

-

-   Translate a socket address *sockaddr* into a 2-tuple ``(host, port)``. Depending

-   on the settings of *flags*, the result can contain a fully-qualified domain name

-   or numeric address representation in *host*.  Similarly, *port* can contain a

-   string port name or a numeric port number.

-

-   .. versionadded:: 2.2

-

-

-.. function:: getprotobyname(protocolname)

-

-   Translate an Internet protocol name (for example, ``'icmp'``) to a constant

-   suitable for passing as the (optional) third argument to the :func:`socket`

-   function.  This is usually only needed for sockets opened in "raw" mode

-   (:const:`SOCK_RAW`); for the normal socket modes, the correct protocol is chosen

-   automatically if the protocol is omitted or zero.

-

-

-.. function:: getservbyname(servicename[, protocolname])

-

-   Translate an Internet service name and protocol name to a port number for that

-   service.  The optional protocol name, if given, should be ``'tcp'`` or

-   ``'udp'``, otherwise any protocol will match.

-

-

-.. function:: getservbyport(port[, protocolname])

-

-   Translate an Internet port number and protocol name to a service name for that

-   service.  The optional protocol name, if given, should be ``'tcp'`` or

-   ``'udp'``, otherwise any protocol will match.

-

-

-.. function:: socket([family[, type[, proto]]])

-

-   Create a new socket using the given address family, socket type and protocol

-   number.  The address family should be :const:`AF_INET` (the default),

-   :const:`AF_INET6` or :const:`AF_UNIX`.  The socket type should be

-   :const:`SOCK_STREAM` (the default), :const:`SOCK_DGRAM` or perhaps one of the

-   other ``SOCK_`` constants.  The protocol number is usually zero and may be

-   omitted in that case.

-

-

-.. function:: socketpair([family[, type[, proto]]])

-

-   Build a pair of connected socket objects using the given address family, socket

-   type, and protocol number.  Address family, socket type, and protocol number are

-   as for the :func:`socket` function above. The default family is :const:`AF_UNIX`

-   if defined on the platform; otherwise, the default is :const:`AF_INET`.

-   Availability: Unix.

-

-   .. versionadded:: 2.4

-

-

-.. function:: fromfd(fd, family, type[, proto])

-

-   Duplicate the file descriptor *fd* (an integer as returned by a file object's

-   :meth:`fileno` method) and build a socket object from the result.  Address

-   family, socket type and protocol number are as for the :func:`socket` function

-   above. The file descriptor should refer to a socket, but this is not checked ---

-   subsequent operations on the object may fail if the file descriptor is invalid.

-   This function is rarely needed, but can be used to get or set socket options on

-   a socket passed to a program as standard input or output (such as a server

-   started by the Unix inet daemon).  The socket is assumed to be in blocking mode.

-   Availability: Unix.

-

-

-.. function:: ntohl(x)

-

-   Convert 32-bit positive integers from network to host byte order.  On machines

-   where the host byte order is the same as network byte order, this is a no-op;

-   otherwise, it performs a 4-byte swap operation.

-

-

-.. function:: ntohs(x)

-

-   Convert 16-bit positive integers from network to host byte order.  On machines

-   where the host byte order is the same as network byte order, this is a no-op;

-   otherwise, it performs a 2-byte swap operation.

-

-

-.. function:: htonl(x)

-

-   Convert 32-bit positive integers from host to network byte order.  On machines

-   where the host byte order is the same as network byte order, this is a no-op;

-   otherwise, it performs a 4-byte swap operation.

-

-

-.. function:: htons(x)

-

-   Convert 16-bit positive integers from host to network byte order.  On machines

-   where the host byte order is the same as network byte order, this is a no-op;

-   otherwise, it performs a 2-byte swap operation.

-

-

-.. function:: inet_aton(ip_string)

-

-   Convert an IPv4 address from dotted-quad string format (for example,

-   '123.45.67.89') to 32-bit packed binary format, as a string four characters in

-   length.  This is useful when conversing with a program that uses the standard C

-   library and needs objects of type :ctype:`struct in_addr`, which is the C type

-   for the 32-bit packed binary this function returns.

-

-   If the IPv4 address string passed to this function is invalid,

-   :exc:`socket.error` will be raised. Note that exactly what is valid depends on

-   the underlying C implementation of :cfunc:`inet_aton`.

-

-   :func:`inet_aton` does not support IPv6, and :func:`getnameinfo` should be used

-   instead for IPv4/v6 dual stack support.

-

-

-.. function:: inet_ntoa(packed_ip)

-

-   Convert a 32-bit packed IPv4 address (a string four characters in length) to its

-   standard dotted-quad string representation (for example, '123.45.67.89').  This

-   is useful when conversing with a program that uses the standard C library and

-   needs objects of type :ctype:`struct in_addr`, which is the C type for the

-   32-bit packed binary data this function takes as an argument.

-

-   If the string passed to this function is not exactly 4 bytes in length,

-   :exc:`socket.error` will be raised. :func:`inet_ntoa` does not support IPv6, and

-   :func:`getnameinfo` should be used instead for IPv4/v6 dual stack support.

-

-

-.. function:: inet_pton(address_family, ip_string)

-

-   Convert an IP address from its family-specific string format to a packed, binary

-   format. :func:`inet_pton` is useful when a library or network protocol calls for

-   an object of type :ctype:`struct in_addr` (similar to :func:`inet_aton`) or

-   :ctype:`struct in6_addr`.

-

-   Supported values for *address_family* are currently :const:`AF_INET` and

-   :const:`AF_INET6`. If the IP address string *ip_string* is invalid,

-   :exc:`socket.error` will be raised. Note that exactly what is valid depends on

-   both the value of *address_family* and the underlying implementation of

-   :cfunc:`inet_pton`.

-

-   Availability: Unix (maybe not all platforms).

-

-   .. versionadded:: 2.3

-

-

-.. function:: inet_ntop(address_family, packed_ip)

-

-   Convert a packed IP address (a string of some number of characters) to its

-   standard, family-specific string representation (for example, ``'7.10.0.5'`` or

-   ``'5aef:2b::8'``) :func:`inet_ntop` is useful when a library or network protocol

-   returns an object of type :ctype:`struct in_addr` (similar to :func:`inet_ntoa`)

-   or :ctype:`struct in6_addr`.

-

-   Supported values for *address_family* are currently :const:`AF_INET` and

-   :const:`AF_INET6`. If the string *packed_ip* is not the correct length for the

-   specified address family, :exc:`ValueError` will be raised.  A

-   :exc:`socket.error` is raised for errors from the call to :func:`inet_ntop`.

-

-   Availability: Unix (maybe not all platforms).

-

-   .. versionadded:: 2.3

-

-

-.. function:: getdefaulttimeout()

-

-   Return the default timeout in floating seconds for new socket objects. A value

-   of ``None`` indicates that new socket objects have no timeout. When the socket

-   module is first imported, the default is ``None``.

-

-   .. versionadded:: 2.3

-

-

-.. function:: setdefaulttimeout(timeout)

-

-   Set the default timeout in floating seconds for new socket objects. A value of

-   ``None`` indicates that new socket objects have no timeout. When the socket

-   module is first imported, the default is ``None``.

-

-   .. versionadded:: 2.3

-

-

-.. data:: SocketType

-

-   This is a Python type object that represents the socket object type. It is the

-   same as ``type(socket(...))``.

-

-

-.. seealso::

-

-   Module :mod:`SocketServer`

-      Classes that simplify writing network servers.

-

-

-.. _socket-objects:

-

-Socket Objects

---------------

-

-Socket objects have the following methods.  Except for :meth:`makefile` these

-correspond to Unix system calls applicable to sockets.

-

-

-.. method:: socket.accept()

-

-   Accept a connection. The socket must be bound to an address and listening for

-   connections. The return value is a pair ``(conn, address)`` where *conn* is a

-   *new* socket object usable to send and receive data on the connection, and

-   *address* is the address bound to the socket on the other end of the connection.

-

-

-.. method:: socket.bind(address)

-

-   Bind the socket to *address*.  The socket must not already be bound. (The format

-   of *address* depends on the address family --- see above.)

-

-   .. note::

-

-      This method has historically accepted a pair of parameters for :const:`AF_INET`

-      addresses instead of only a tuple.  This was never intentional and is no longer

-      available in Python 2.0 and later.

-

-

-.. method:: socket.close()

-

-   Close the socket.  All future operations on the socket object will fail. The

-   remote end will receive no more data (after queued data is flushed). Sockets are

-   automatically closed when they are garbage-collected.

-

-

-.. method:: socket.connect(address)

-

-   Connect to a remote socket at *address*. (The format of *address* depends on the

-   address family --- see above.)

-

-   .. note::

-

-      This method has historically accepted a pair of parameters for :const:`AF_INET`

-      addresses instead of only a tuple.  This was never intentional and is no longer

-      available in Python 2.0 and later.

-

-

-.. method:: socket.connect_ex(address)

-

-   Like ``connect(address)``, but return an error indicator instead of raising an

-   exception for errors returned by the C-level :cfunc:`connect` call (other

-   problems, such as "host not found," can still raise exceptions).  The error

-   indicator is ``0`` if the operation succeeded, otherwise the value of the

-   :cdata:`errno` variable.  This is useful to support, for example, asynchronous

-   connects.

-

-   .. note::

-

-      This method has historically accepted a pair of parameters for :const:`AF_INET`

-      addresses instead of only a tuple. This was never intentional and is no longer

-      available in Python 2.0 and later.

-

-

-.. method:: socket.fileno()

-

-   Return the socket's file descriptor (a small integer).  This is useful with

-   :func:`select.select`.

-

-   Under Windows the small integer returned by this method cannot be used where a

-   file descriptor can be used (such as :func:`os.fdopen`).  Unix does not have

-   this limitation.

-

-

-.. method:: socket.getpeername()

-

-   Return the remote address to which the socket is connected.  This is useful to

-   find out the port number of a remote IPv4/v6 socket, for instance. (The format

-   of the address returned depends on the address family --- see above.)  On some

-   systems this function is not supported.

-

-

-.. method:: socket.getsockname()

-

-   Return the socket's own address.  This is useful to find out the port number of

-   an IPv4/v6 socket, for instance. (The format of the address returned depends on

-   the address family --- see above.)

-

-

-.. method:: socket.getsockopt(level, optname[, buflen])

-

-   Return the value of the given socket option (see the Unix man page

-   :manpage:`getsockopt(2)`).  The needed symbolic constants (:const:`SO_\*` etc.)

-   are defined in this module.  If *buflen* is absent, an integer option is assumed

-   and its integer value is returned by the function.  If *buflen* is present, it

-   specifies the maximum length of the buffer used to receive the option in, and

-   this buffer is returned as a string.  It is up to the caller to decode the

-   contents of the buffer (see the optional built-in module :mod:`struct` for a way

-   to decode C structures encoded as strings).

-

-   

-.. method:: socket.ioctl(control, option)

-

-   :platform: Windows 

-   

-   The `meth:ioctl` method is a limited interface to the WSAIoctl system

-   interface. Please refer to the MSDN documentation for more information.

-   

-   .. versionadded:: 2.6

-

-

-.. method:: socket.listen(backlog)

-

-   Listen for connections made to the socket.  The *backlog* argument specifies the

-   maximum number of queued connections and should be at least 1; the maximum value

-   is system-dependent (usually 5).

-

-

-.. method:: socket.makefile([mode[, bufsize]])

-

-   .. index:: single: I/O control; buffering

-

-   Return a :dfn:`file object` associated with the socket.  (File objects are

-   described in :ref:`bltin-file-objects`.) The file object

-   references a :cfunc:`dup`\ ped version of the socket file descriptor, so the

-   file object and socket object may be closed or garbage-collected independently.

-   The socket must be in blocking mode (it can not have a timeout). The optional

-   *mode* and *bufsize* arguments are interpreted the same way as by the built-in

-   :func:`file` function.

-

-

-.. method:: socket.recv(bufsize[, flags])

-

-   Receive data from the socket.  The return value is a string representing the

-   data received.  The maximum amount of data to be received at once is specified

-   by *bufsize*.  See the Unix manual page :manpage:`recv(2)` for the meaning of

-   the optional argument *flags*; it defaults to zero.

-

-   .. note::

-

-      For best match with hardware and network realities, the value of  *bufsize*

-      should be a relatively small power of 2, for example, 4096.

-

-

-.. method:: socket.recvfrom(bufsize[, flags])

-

-   Receive data from the socket.  The return value is a pair ``(string, address)``

-   where *string* is a string representing the data received and *address* is the

-   address of the socket sending the data.  See the Unix manual page

-   :manpage:`recv(2)` for the meaning of the optional argument *flags*; it defaults

-   to zero. (The format of *address* depends on the address family --- see above.)

-

-

-.. method:: socket.recvfrom_into(buffer[, nbytes[, flags]])

-

-   Receive data from the socket, writing it into *buffer* instead of  creating a

-   new string.  The return value is a pair ``(nbytes, address)`` where *nbytes* is

-   the number of bytes received and *address* is the address of the socket sending

-   the data.  See the Unix manual page :manpage:`recv(2)` for the meaning of the

-   optional argument *flags*; it defaults to zero.  (The format of *address*

-   depends on the address family --- see above.)

-

-   .. versionadded:: 2.5

-

-

-.. method:: socket.recv_into(buffer[, nbytes[, flags]])

-

-   Receive up to *nbytes* bytes from the socket, storing the data into a buffer

-   rather than creating a new string.     If *nbytes* is not specified (or 0),

-   receive up to the size available in the given buffer. See the Unix manual page

-   :manpage:`recv(2)` for the meaning of the optional argument *flags*; it defaults

-   to zero.

-

-   .. versionadded:: 2.5

-

-

-.. method:: socket.send(string[, flags])

-

-   Send data to the socket.  The socket must be connected to a remote socket.  The

-   optional *flags* argument has the same meaning as for :meth:`recv` above.

-   Returns the number of bytes sent. Applications are responsible for checking that

-   all data has been sent; if only some of the data was transmitted, the

-   application needs to attempt delivery of the remaining data.

-

-

-.. method:: socket.sendall(string[, flags])

-

-   Send data to the socket.  The socket must be connected to a remote socket.  The

-   optional *flags* argument has the same meaning as for :meth:`recv` above.

-   Unlike :meth:`send`, this method continues to send data from *string* until

-   either all data has been sent or an error occurs.  ``None`` is returned on

-   success.  On error, an exception is raised, and there is no way to determine how

-   much data, if any, was successfully sent.

-

-

-.. method:: socket.sendto(string[, flags], address)

-

-   Send data to the socket.  The socket should not be connected to a remote socket,

-   since the destination socket is specified by *address*.  The optional *flags*

-   argument has the same meaning as for :meth:`recv` above.  Return the number of

-   bytes sent. (The format of *address* depends on the address family --- see

-   above.)

-

-

-.. method:: socket.setblocking(flag)

-

-   Set blocking or non-blocking mode of the socket: if *flag* is 0, the socket is

-   set to non-blocking, else to blocking mode.  Initially all sockets are in

-   blocking mode.  In non-blocking mode, if a :meth:`recv` call doesn't find any

-   data, or if a :meth:`send` call can't immediately dispose of the data, a

-   :exc:`error` exception is raised; in blocking mode, the calls block until they

-   can proceed. ``s.setblocking(0)`` is equivalent to ``s.settimeout(0)``;

-   ``s.setblocking(1)`` is equivalent to ``s.settimeout(None)``.

-

-

-.. method:: socket.settimeout(value)

-

-   Set a timeout on blocking socket operations.  The *value* argument can be a

-   nonnegative float expressing seconds, or ``None``. If a float is given,

-   subsequent socket operations will raise an :exc:`timeout` exception if the

-   timeout period *value* has elapsed before the operation has completed.  Setting

-   a timeout of ``None`` disables timeouts on socket operations.

-   ``s.settimeout(0.0)`` is equivalent to ``s.setblocking(0)``;

-   ``s.settimeout(None)`` is equivalent to ``s.setblocking(1)``.

-

-   .. versionadded:: 2.3

-

-

-.. method:: socket.gettimeout()

-

-   Return the timeout in floating seconds associated with socket operations, or

-   ``None`` if no timeout is set.  This reflects the last call to

-   :meth:`setblocking` or :meth:`settimeout`.

-

-   .. versionadded:: 2.3

-

-Some notes on socket blocking and timeouts: A socket object can be in one of

-three modes: blocking, non-blocking, or timeout.  Sockets are always created in

-blocking mode.  In blocking mode, operations block until complete.  In

-non-blocking mode, operations fail (with an error that is unfortunately

-system-dependent) if they cannot be completed immediately.  In timeout mode,

-operations fail if they cannot be completed within the timeout specified for the

-socket.  The :meth:`setblocking` method is simply a shorthand for certain

-:meth:`settimeout` calls.

-

-Timeout mode internally sets the socket in non-blocking mode.  The blocking and

-timeout modes are shared between file descriptors and socket objects that refer

-to the same network endpoint.  A consequence of this is that file objects

-returned by the :meth:`makefile` method must only be used when the socket is in

-blocking mode; in timeout or non-blocking mode file operations that cannot be

-completed immediately will fail.

-

-Note that the :meth:`connect` operation is subject to the timeout setting, and

-in general it is recommended to call :meth:`settimeout` before calling

-:meth:`connect`.

-

-

-.. method:: socket.setsockopt(level, optname, value)

-

-   .. index:: module: struct

-

-   Set the value of the given socket option (see the Unix manual page

-   :manpage:`setsockopt(2)`).  The needed symbolic constants are defined in the

-   :mod:`socket` module (:const:`SO_\*` etc.).  The value can be an integer or a

-   string representing a buffer.  In the latter case it is up to the caller to

-   ensure that the string contains the proper bits (see the optional built-in

-   module :mod:`struct` for a way to encode C structures as strings).

-

-

-.. method:: socket.shutdown(how)

-

-   Shut down one or both halves of the connection.  If *how* is :const:`SHUT_RD`,

-   further receives are disallowed.  If *how* is :const:`SHUT_WR`, further sends

-   are disallowed.  If *how* is :const:`SHUT_RDWR`, further sends and receives are

-   disallowed.

-

-Note that there are no methods :meth:`read` or :meth:`write`; use :meth:`recv`

-and :meth:`send` without *flags* argument instead.

-

-Socket objects also have these (read-only) attributes that correspond to the

-values given to the :class:`socket` constructor.

-

-

-.. attribute:: socket.family

-

-   The socket family.

-

-   .. versionadded:: 2.5

-

-

-.. attribute:: socket.type

-

-   The socket type.

-

-   .. versionadded:: 2.5

-

-

-.. attribute:: socket.proto

-

-   The socket protocol.

-

-   .. versionadded:: 2.5

-

-

-.. _socket-example:

-

-Example

--------

-

-Here are four minimal example programs using the TCP/IP protocol: a server that

-echoes all data that it receives back (servicing only one client), and a client

-using it.  Note that a server must perform the sequence :func:`socket`,

-:meth:`bind`, :meth:`listen`, :meth:`accept` (possibly repeating the

-:meth:`accept` to service more than one client), while a client only needs the

-sequence :func:`socket`, :meth:`connect`.  Also note that the server does not

-:meth:`send`/:meth:`recv` on the  socket it is listening on but on the new

-socket returned by :meth:`accept`.

-

-The first two examples support IPv4 only. ::

-

-   # Echo server program

-   import socket

-

-   HOST = ''                 # Symbolic name meaning the local host

-   PORT = 50007              # Arbitrary non-privileged port

-   s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

-   s.bind((HOST, PORT))

-   s.listen(1)

-   conn, addr = s.accept()

-   print 'Connected by', addr

-   while 1:

-       data = conn.recv(1024)

-       if not data: break

-       conn.send(data)

-   conn.close()

-

-::

-

-   # Echo client program

-   import socket

-

-   HOST = 'daring.cwi.nl'    # The remote host

-   PORT = 50007              # The same port as used by the server

-   s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

-   s.connect((HOST, PORT))

-   s.send('Hello, world')

-   data = s.recv(1024)

-   s.close()

-   print 'Received', repr(data)

-

-The next two examples are identical to the above two, but support both IPv4 and

-IPv6. The server side will listen to the first address family available (it

-should listen to both instead). On most of IPv6-ready systems, IPv6 will take

-precedence and the server may not accept IPv4 traffic. The client side will try

-to connect to the all addresses returned as a result of the name resolution, and

-sends traffic to the first one connected successfully. ::

-

-   # Echo server program

-   import socket

-   import sys

-

-   HOST = ''                 # Symbolic name meaning the local host

-   PORT = 50007              # Arbitrary non-privileged port

-   s = None

-   for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC, socket.SOCK_STREAM, 0, socket.AI_PASSIVE):

-       af, socktype, proto, canonname, sa = res

-       try:

-   	s = socket.socket(af, socktype, proto)

-       except socket.error, msg:

-   	s = None

-   	continue

-       try:

-   	s.bind(sa)

-   	s.listen(1)

-       except socket.error, msg:

-   	s.close()

-   	s = None

-   	continue

-       break

-   if s is None:

-       print 'could not open socket'

-       sys.exit(1)

-   conn, addr = s.accept()

-   print 'Connected by', addr

-   while 1:

-       data = conn.recv(1024)

-       if not data: break

-       conn.send(data)

-   conn.close()

-

-::

-

-   # Echo client program

-   import socket

-   import sys

-

-   HOST = 'daring.cwi.nl'    # The remote host

-   PORT = 50007              # The same port as used by the server

-   s = None

-   for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC, socket.SOCK_STREAM):

-       af, socktype, proto, canonname, sa = res

-       try:

-   	s = socket.socket(af, socktype, proto)

-       except socket.error, msg:

-   	s = None

-   	continue

-       try:

-   	s.connect(sa)

-       except socket.error, msg:

-   	s.close()

-   	s = None

-   	continue

-       break

-   if s is None:

-       print 'could not open socket'

-       sys.exit(1)

-   s.send('Hello, world')

-   data = s.recv(1024)

-   s.close()

-   print 'Received', repr(data)

-

-   

-The last example shows how to write a very simple network sniffer with raw

-sockets on Windows. The example requires administrator priviliges to modify

-the interface::

-

-   import socket

-

-   # the public network interface

-   HOST = socket.gethostbyname(socket.gethostname())

-   

-   # create a raw socket and bind it to the public interface

-   s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_IP)

-   s.bind((HOST, 0))

-   

-   # Include IP headers

-   s.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1)

-   

-   # receive all packages

-   s.ioctl(socket.SIO_RCVALL, socket.RCVALL_ON)

-   

-   # receive a package

-   print s.recvfrom(65565)

-   

-   # disabled promiscous mode

-   s.ioctl(socket.SIO_RCVALL, socket.RCVALL_OFF)

+
+:mod:`socket` --- Low-level networking interface
+================================================
+
+.. module:: socket
+   :synopsis: Low-level networking interface.
+
+
+This module provides access to the BSD *socket* interface. It is available on
+all modern Unix systems, Windows, Mac OS X, BeOS, OS/2, and probably additional
+platforms.
+
+.. note::
+
+   Some behavior may be platform dependent, since calls are made to the operating
+   system socket APIs.
+
+For an introduction to socket programming (in C), see the following papers: An
+Introductory 4.3BSD Interprocess Communication Tutorial, by Stuart Sechrest and
+An Advanced 4.3BSD Interprocess Communication Tutorial, by Samuel J.  Leffler et
+al, both in the UNIX Programmer's Manual, Supplementary Documents 1 (sections
+PS1:7 and PS1:8).  The platform-specific reference material for the various
+socket-related system calls are also a valuable source of information on the
+details of socket semantics.  For Unix, refer to the manual pages; for Windows,
+see the WinSock (or Winsock 2) specification. For IPv6-ready APIs, readers may
+want to refer to :rfc:`2553` titled Basic Socket Interface Extensions for IPv6.
+
+.. index:: object: socket
+
+The Python interface is a straightforward transliteration of the Unix system
+call and library interface for sockets to Python's object-oriented style: the
+:func:`socket` function returns a :dfn:`socket object` whose methods implement
+the various socket system calls.  Parameter types are somewhat higher-level than
+in the C interface: as with :meth:`read` and :meth:`write` operations on Python
+files, buffer allocation on receive operations is automatic, and buffer length
+is implicit on send operations.
+
+Socket addresses are represented as follows: A single string is used for the
+:const:`AF_UNIX` address family. A pair ``(host, port)`` is used for the
+:const:`AF_INET` address family, where *host* is a string representing either a
+hostname in Internet domain notation like ``'daring.cwi.nl'`` or an IPv4 address
+like ``'100.50.200.5'``, and *port* is an integral port number. For
+:const:`AF_INET6` address family, a four-tuple ``(host, port, flowinfo,
+scopeid)`` is used, where *flowinfo* and *scopeid* represents ``sin6_flowinfo``
+and ``sin6_scope_id`` member in :const:`struct sockaddr_in6` in C. For
+:mod:`socket` module methods, *flowinfo* and *scopeid* can be omitted just for
+backward compatibility. Note, however, omission of *scopeid* can cause problems
+in manipulating scoped IPv6 addresses. Other address families are currently not
+supported. The address format required by a particular socket object is
+automatically selected based on the address family specified when the socket
+object was created.
+
+For IPv4 addresses, two special forms are accepted instead of a host address:
+the empty string represents :const:`INADDR_ANY`, and the string
+``'<broadcast>'`` represents :const:`INADDR_BROADCAST`. The behavior is not
+available for IPv6 for backward compatibility, therefore, you may want to avoid
+these if you intend to support IPv6 with your Python programs.
+
+If you use a hostname in the *host* portion of IPv4/v6 socket address, the
+program may show a nondeterministic behavior, as Python uses the first address
+returned from the DNS resolution.  The socket address will be resolved
+differently into an actual IPv4/v6 address, depending on the results from DNS
+resolution and/or the host configuration.  For deterministic behavior use a
+numeric address in *host* portion.
+
+.. versionadded:: 2.5
+   AF_NETLINK sockets are represented as  pairs ``pid, groups``.
+
+All errors raise exceptions.  The normal exceptions for invalid argument types
+and out-of-memory conditions can be raised; errors related to socket or address
+semantics raise the error :exc:`socket.error`.
+
+Non-blocking mode is supported through :meth:`setblocking`.  A generalization of
+this based on timeouts is supported through :meth:`settimeout`.
+
+The module :mod:`socket` exports the following constants and functions:
+
+
+.. exception:: error
+
+   .. index:: module: errno
+
+   This exception is raised for socket-related errors. The accompanying value is
+   either a string telling what went wrong or a pair ``(errno, string)``
+   representing an error returned by a system call, similar to the value
+   accompanying :exc:`os.error`. See the module :mod:`errno`, which contains names
+   for the error codes defined by the underlying operating system.
+
+   .. versionchanged:: 2.6
+      :exc:`socket.error` is now a child class of :exc:`IOError`.
+
+
+.. exception:: herror
+
+   This exception is raised for address-related errors, i.e. for functions that use
+   *h_errno* in the C API, including :func:`gethostbyname_ex` and
+   :func:`gethostbyaddr`.
+
+   The accompanying value is a pair ``(h_errno, string)`` representing an error
+   returned by a library call. *string* represents the description of *h_errno*, as
+   returned by the :cfunc:`hstrerror` C function.
+
+
+.. exception:: gaierror
+
+   This exception is raised for address-related errors, for :func:`getaddrinfo` and
+   :func:`getnameinfo`. The accompanying value is a pair ``(error, string)``
+   representing an error returned by a library call. *string* represents the
+   description of *error*, as returned by the :cfunc:`gai_strerror` C function. The
+   *error* value will match one of the :const:`EAI_\*` constants defined in this
+   module.
+
+
+.. exception:: timeout
+
+   This exception is raised when a timeout occurs on a socket which has had
+   timeouts enabled via a prior call to :meth:`settimeout`.  The accompanying value
+   is a string whose value is currently always "timed out".
+
+   .. versionadded:: 2.3
+
+
+.. data:: AF_UNIX
+          AF_INET
+          AF_INET6
+
+   These constants represent the address (and protocol) families, used for the
+   first argument to :func:`socket`.  If the :const:`AF_UNIX` constant is not
+   defined then this protocol is unsupported.
+
+
+.. data:: SOCK_STREAM
+          SOCK_DGRAM
+          SOCK_RAW
+          SOCK_RDM
+          SOCK_SEQPACKET
+
+   These constants represent the socket types, used for the second argument to
+   :func:`socket`. (Only :const:`SOCK_STREAM` and :const:`SOCK_DGRAM` appear to be
+   generally useful.)
+
+
+.. data:: SO_*
+          SOMAXCONN
+          MSG_*
+          SOL_*
+          IPPROTO_*
+          IPPORT_*
+          INADDR_*
+          IP_*
+          IPV6_*
+          EAI_*
+          AI_*
+          NI_*
+          TCP_*
+
+   Many constants of these forms, documented in the Unix documentation on sockets
+   and/or the IP protocol, are also defined in the socket module. They are
+   generally used in arguments to the :meth:`setsockopt` and :meth:`getsockopt`
+   methods of socket objects.  In most cases, only those symbols that are defined
+   in the Unix header files are defined; for a few symbols, default values are
+   provided.
+
+.. data:: SIO_*
+          RCVALL_*
+          
+   Constants for Windows' WSAIoctl(). The constants are used as arguments to the
+   :meth:`ioctl` method of socket objects.
+   
+   .. versionadded:: 2.6
+
+
+.. data:: has_ipv6
+
+   This constant contains a boolean value which indicates if IPv6 is supported on
+   this platform.
+
+   .. versionadded:: 2.3
+
+
+.. function:: create_connection(address[, timeout])
+
+   Connects to the *address* received (as usual, a ``(host, port)`` pair), with an
+   optional timeout for the connection.  Especially useful for higher-level
+   protocols, it is not normally used directly from application-level code.
+   Passing the optional *timeout* parameter will set the timeout on the socket
+   instance (if it is not given or ``None``, the global default timeout setting is
+   used).
+
+   .. versionadded:: 2.6
+
+
+.. function:: getaddrinfo(host, port[, family[, socktype[, proto[, flags]]]])
+
+   Resolves the *host*/*port* argument, into a sequence of 5-tuples that contain
+   all the necessary argument for the sockets manipulation. *host* is a domain
+   name, a string representation of IPv4/v6 address or ``None``. *port* is a string
+   service name (like ``'http'``), a numeric port number or ``None``.
+
+   The rest of the arguments are optional and must be numeric if specified.  For
+   *host* and *port*, by passing either an empty string or ``None``, you can pass
+   ``NULL`` to the C API.  The :func:`getaddrinfo` function returns a list of
+   5-tuples with the following structure:
+
+   ``(family, socktype, proto, canonname, sockaddr)``
+
+   *family*, *socktype*, *proto* are all integer and are meant to be passed to the
+   :func:`socket` function. *canonname* is a string representing the canonical name
+   of the *host*. It can be a numeric IPv4/v6 address when :const:`AI_CANONNAME` is
+   specified for a numeric *host*. *sockaddr* is a tuple describing a socket
+   address, as described above. See the source for :mod:`socket` and other
+   library modules for a typical usage of the function.
+
+   .. versionadded:: 2.2
+
+
+.. function:: getfqdn([name])
+
+   Return a fully qualified domain name for *name*. If *name* is omitted or empty,
+   it is interpreted as the local host.  To find the fully qualified name, the
+   hostname returned by :func:`gethostbyaddr` is checked, then aliases for the
+   host, if available.  The first name which includes a period is selected.  In
+   case no fully qualified domain name is available, the hostname as returned by
+   :func:`gethostname` is returned.
+
+   .. versionadded:: 2.0
+
+
+.. function:: gethostbyname(hostname)
+
+   Translate a host name to IPv4 address format.  The IPv4 address is returned as a
+   string, such as  ``'100.50.200.5'``.  If the host name is an IPv4 address itself
+   it is returned unchanged.  See :func:`gethostbyname_ex` for a more complete
+   interface. :func:`gethostbyname` does not support IPv6 name resolution, and
+   :func:`getaddrinfo` should be used instead for IPv4/v6 dual stack support.
+
+
+.. function:: gethostbyname_ex(hostname)
+
+   Translate a host name to IPv4 address format, extended interface. Return a
+   triple ``(hostname, aliaslist, ipaddrlist)`` where *hostname* is the primary
+   host name responding to the given *ip_address*, *aliaslist* is a (possibly
+   empty) list of alternative host names for the same address, and *ipaddrlist* is
+   a list of IPv4 addresses for the same interface on the same host (often but not
+   always a single address). :func:`gethostbyname_ex` does not support IPv6 name
+   resolution, and :func:`getaddrinfo` should be used instead for IPv4/v6 dual
+   stack support.
+
+
+.. function:: gethostname()
+
+   Return a string containing the hostname of the machine where  the Python
+   interpreter is currently executing. If you want to know the current machine's IP
+   address, you may want to use ``gethostbyname(gethostname())``. This operation
+   assumes that there is a valid address-to-host mapping for the host, and the
+   assumption does not always hold. Note: :func:`gethostname` doesn't always return
+   the fully qualified domain name; use ``getfqdn()`` (see above).
+
+
+.. function:: gethostbyaddr(ip_address)
+
+   Return a triple ``(hostname, aliaslist, ipaddrlist)`` where *hostname* is the
+   primary host name responding to the given *ip_address*, *aliaslist* is a
+   (possibly empty) list of alternative host names for the same address, and
+   *ipaddrlist* is a list of IPv4/v6 addresses for the same interface on the same
+   host (most likely containing only a single address). To find the fully qualified
+   domain name, use the function :func:`getfqdn`. :func:`gethostbyaddr` supports
+   both IPv4 and IPv6.
+
+
+.. function:: getnameinfo(sockaddr, flags)
+
+   Translate a socket address *sockaddr* into a 2-tuple ``(host, port)``. Depending
+   on the settings of *flags*, the result can contain a fully-qualified domain name
+   or numeric address representation in *host*.  Similarly, *port* can contain a
+   string port name or a numeric port number.
+
+   .. versionadded:: 2.2
+
+
+.. function:: getprotobyname(protocolname)
+
+   Translate an Internet protocol name (for example, ``'icmp'``) to a constant
+   suitable for passing as the (optional) third argument to the :func:`socket`
+   function.  This is usually only needed for sockets opened in "raw" mode
+   (:const:`SOCK_RAW`); for the normal socket modes, the correct protocol is chosen
+   automatically if the protocol is omitted or zero.
+
+
+.. function:: getservbyname(servicename[, protocolname])
+
+   Translate an Internet service name and protocol name to a port number for that
+   service.  The optional protocol name, if given, should be ``'tcp'`` or
+   ``'udp'``, otherwise any protocol will match.
+
+
+.. function:: getservbyport(port[, protocolname])
+
+   Translate an Internet port number and protocol name to a service name for that
+   service.  The optional protocol name, if given, should be ``'tcp'`` or
+   ``'udp'``, otherwise any protocol will match.
+
+
+.. function:: socket([family[, type[, proto]]])
+
+   Create a new socket using the given address family, socket type and protocol
+   number.  The address family should be :const:`AF_INET` (the default),
+   :const:`AF_INET6` or :const:`AF_UNIX`.  The socket type should be
+   :const:`SOCK_STREAM` (the default), :const:`SOCK_DGRAM` or perhaps one of the
+   other ``SOCK_`` constants.  The protocol number is usually zero and may be
+   omitted in that case.
+
+
+.. function:: socketpair([family[, type[, proto]]])
+
+   Build a pair of connected socket objects using the given address family, socket
+   type, and protocol number.  Address family, socket type, and protocol number are
+   as for the :func:`socket` function above. The default family is :const:`AF_UNIX`
+   if defined on the platform; otherwise, the default is :const:`AF_INET`.
+   Availability: Unix.
+
+   .. versionadded:: 2.4
+
+
+.. function:: fromfd(fd, family, type[, proto])
+
+   Duplicate the file descriptor *fd* (an integer as returned by a file object's
+   :meth:`fileno` method) and build a socket object from the result.  Address
+   family, socket type and protocol number are as for the :func:`socket` function
+   above. The file descriptor should refer to a socket, but this is not checked ---
+   subsequent operations on the object may fail if the file descriptor is invalid.
+   This function is rarely needed, but can be used to get or set socket options on
+   a socket passed to a program as standard input or output (such as a server
+   started by the Unix inet daemon).  The socket is assumed to be in blocking mode.
+   Availability: Unix.
+
+
+.. function:: ntohl(x)
+
+   Convert 32-bit positive integers from network to host byte order.  On machines
+   where the host byte order is the same as network byte order, this is a no-op;
+   otherwise, it performs a 4-byte swap operation.
+
+
+.. function:: ntohs(x)
+
+   Convert 16-bit positive integers from network to host byte order.  On machines
+   where the host byte order is the same as network byte order, this is a no-op;
+   otherwise, it performs a 2-byte swap operation.
+
+
+.. function:: htonl(x)
+
+   Convert 32-bit positive integers from host to network byte order.  On machines
+   where the host byte order is the same as network byte order, this is a no-op;
+   otherwise, it performs a 4-byte swap operation.
+
+
+.. function:: htons(x)
+
+   Convert 16-bit positive integers from host to network byte order.  On machines
+   where the host byte order is the same as network byte order, this is a no-op;
+   otherwise, it performs a 2-byte swap operation.
+
+
+.. function:: inet_aton(ip_string)
+
+   Convert an IPv4 address from dotted-quad string format (for example,
+   '123.45.67.89') to 32-bit packed binary format, as a string four characters in
+   length.  This is useful when conversing with a program that uses the standard C
+   library and needs objects of type :ctype:`struct in_addr`, which is the C type
+   for the 32-bit packed binary this function returns.
+
+   If the IPv4 address string passed to this function is invalid,
+   :exc:`socket.error` will be raised. Note that exactly what is valid depends on
+   the underlying C implementation of :cfunc:`inet_aton`.
+
+   :func:`inet_aton` does not support IPv6, and :func:`getnameinfo` should be used
+   instead for IPv4/v6 dual stack support.
+
+
+.. function:: inet_ntoa(packed_ip)
+
+   Convert a 32-bit packed IPv4 address (a string four characters in length) to its
+   standard dotted-quad string representation (for example, '123.45.67.89').  This
+   is useful when conversing with a program that uses the standard C library and
+   needs objects of type :ctype:`struct in_addr`, which is the C type for the
+   32-bit packed binary data this function takes as an argument.
+
+   If the string passed to this function is not exactly 4 bytes in length,
+   :exc:`socket.error` will be raised. :func:`inet_ntoa` does not support IPv6, and
+   :func:`getnameinfo` should be used instead for IPv4/v6 dual stack support.
+
+
+.. function:: inet_pton(address_family, ip_string)
+
+   Convert an IP address from its family-specific string format to a packed, binary
+   format. :func:`inet_pton` is useful when a library or network protocol calls for
+   an object of type :ctype:`struct in_addr` (similar to :func:`inet_aton`) or
+   :ctype:`struct in6_addr`.
+
+   Supported values for *address_family* are currently :const:`AF_INET` and
+   :const:`AF_INET6`. If the IP address string *ip_string* is invalid,
+   :exc:`socket.error` will be raised. Note that exactly what is valid depends on
+   both the value of *address_family* and the underlying implementation of
+   :cfunc:`inet_pton`.
+
+   Availability: Unix (maybe not all platforms).
+
+   .. versionadded:: 2.3
+
+
+.. function:: inet_ntop(address_family, packed_ip)
+
+   Convert a packed IP address (a string of some number of characters) to its
+   standard, family-specific string representation (for example, ``'7.10.0.5'`` or
+   ``'5aef:2b::8'``) :func:`inet_ntop` is useful when a library or network protocol
+   returns an object of type :ctype:`struct in_addr` (similar to :func:`inet_ntoa`)
+   or :ctype:`struct in6_addr`.
+
+   Supported values for *address_family* are currently :const:`AF_INET` and
+   :const:`AF_INET6`. If the string *packed_ip* is not the correct length for the
+   specified address family, :exc:`ValueError` will be raised.  A
+   :exc:`socket.error` is raised for errors from the call to :func:`inet_ntop`.
+
+   Availability: Unix (maybe not all platforms).
+
+   .. versionadded:: 2.3
+
+
+.. function:: getdefaulttimeout()
+
+   Return the default timeout in floating seconds for new socket objects. A value
+   of ``None`` indicates that new socket objects have no timeout. When the socket
+   module is first imported, the default is ``None``.
+
+   .. versionadded:: 2.3
+
+
+.. function:: setdefaulttimeout(timeout)
+
+   Set the default timeout in floating seconds for new socket objects. A value of
+   ``None`` indicates that new socket objects have no timeout. When the socket
+   module is first imported, the default is ``None``.
+
+   .. versionadded:: 2.3
+
+
+.. data:: SocketType
+
+   This is a Python type object that represents the socket object type. It is the
+   same as ``type(socket(...))``.
+
+
+.. seealso::
+
+   Module :mod:`SocketServer`
+      Classes that simplify writing network servers.
+
+
+.. _socket-objects:
+
+Socket Objects
+--------------
+
+Socket objects have the following methods.  Except for :meth:`makefile` these
+correspond to Unix system calls applicable to sockets.
+
+
+.. method:: socket.accept()
+
+   Accept a connection. The socket must be bound to an address and listening for
+   connections. The return value is a pair ``(conn, address)`` where *conn* is a
+   *new* socket object usable to send and receive data on the connection, and
+   *address* is the address bound to the socket on the other end of the connection.
+
+
+.. method:: socket.bind(address)
+
+   Bind the socket to *address*.  The socket must not already be bound. (The format
+   of *address* depends on the address family --- see above.)
+
+   .. note::
+
+      This method has historically accepted a pair of parameters for :const:`AF_INET`
+      addresses instead of only a tuple.  This was never intentional and is no longer
+      available in Python 2.0 and later.
+
+
+.. method:: socket.close()
+
+   Close the socket.  All future operations on the socket object will fail. The
+   remote end will receive no more data (after queued data is flushed). Sockets are
+   automatically closed when they are garbage-collected.
+
+
+.. method:: socket.connect(address)
+
+   Connect to a remote socket at *address*. (The format of *address* depends on the
+   address family --- see above.)
+
+   .. note::
+
+      This method has historically accepted a pair of parameters for :const:`AF_INET`
+      addresses instead of only a tuple.  This was never intentional and is no longer
+      available in Python 2.0 and later.
+
+
+.. method:: socket.connect_ex(address)
+
+   Like ``connect(address)``, but return an error indicator instead of raising an
+   exception for errors returned by the C-level :cfunc:`connect` call (other
+   problems, such as "host not found," can still raise exceptions).  The error
+   indicator is ``0`` if the operation succeeded, otherwise the value of the
+   :cdata:`errno` variable.  This is useful to support, for example, asynchronous
+   connects.
+
+   .. note::
+
+      This method has historically accepted a pair of parameters for :const:`AF_INET`
+      addresses instead of only a tuple. This was never intentional and is no longer
+      available in Python 2.0 and later.
+
+
+.. method:: socket.fileno()
+
+   Return the socket's file descriptor (a small integer).  This is useful with
+   :func:`select.select`.
+
+   Under Windows the small integer returned by this method cannot be used where a
+   file descriptor can be used (such as :func:`os.fdopen`).  Unix does not have
+   this limitation.
+
+
+.. method:: socket.getpeername()
+
+   Return the remote address to which the socket is connected.  This is useful to
+   find out the port number of a remote IPv4/v6 socket, for instance. (The format
+   of the address returned depends on the address family --- see above.)  On some
+   systems this function is not supported.
+
+
+.. method:: socket.getsockname()
+
+   Return the socket's own address.  This is useful to find out the port number of
+   an IPv4/v6 socket, for instance. (The format of the address returned depends on
+   the address family --- see above.)
+
+
+.. method:: socket.getsockopt(level, optname[, buflen])
+
+   Return the value of the given socket option (see the Unix man page
+   :manpage:`getsockopt(2)`).  The needed symbolic constants (:const:`SO_\*` etc.)
+   are defined in this module.  If *buflen* is absent, an integer option is assumed
+   and its integer value is returned by the function.  If *buflen* is present, it
+   specifies the maximum length of the buffer used to receive the option in, and
+   this buffer is returned as a string.  It is up to the caller to decode the
+   contents of the buffer (see the optional built-in module :mod:`struct` for a way
+   to decode C structures encoded as strings).
+
+   
+.. method:: socket.ioctl(control, option)
+
+   :platform: Windows 
+   
+   The `meth:ioctl` method is a limited interface to the WSAIoctl system
+   interface. Please refer to the MSDN documentation for more information.
+   
+   .. versionadded:: 2.6
+
+
+.. method:: socket.listen(backlog)
+
+   Listen for connections made to the socket.  The *backlog* argument specifies the
+   maximum number of queued connections and should be at least 1; the maximum value
+   is system-dependent (usually 5).
+
+
+.. method:: socket.makefile([mode[, bufsize]])
+
+   .. index:: single: I/O control; buffering
+
+   Return a :dfn:`file object` associated with the socket.  (File objects are
+   described in :ref:`bltin-file-objects`.) The file object
+   references a :cfunc:`dup`\ ped version of the socket file descriptor, so the
+   file object and socket object may be closed or garbage-collected independently.
+   The socket must be in blocking mode (it can not have a timeout). The optional
+   *mode* and *bufsize* arguments are interpreted the same way as by the built-in
+   :func:`file` function.
+
+
+.. method:: socket.recv(bufsize[, flags])
+
+   Receive data from the socket.  The return value is a string representing the
+   data received.  The maximum amount of data to be received at once is specified
+   by *bufsize*.  See the Unix manual page :manpage:`recv(2)` for the meaning of
+   the optional argument *flags*; it defaults to zero.
+
+   .. note::
+
+      For best match with hardware and network realities, the value of  *bufsize*
+      should be a relatively small power of 2, for example, 4096.
+
+
+.. method:: socket.recvfrom(bufsize[, flags])
+
+   Receive data from the socket.  The return value is a pair ``(string, address)``
+   where *string* is a string representing the data received and *address* is the
+   address of the socket sending the data.  See the Unix manual page
+   :manpage:`recv(2)` for the meaning of the optional argument *flags*; it defaults
+   to zero. (The format of *address* depends on the address family --- see above.)
+
+
+.. method:: socket.recvfrom_into(buffer[, nbytes[, flags]])
+
+   Receive data from the socket, writing it into *buffer* instead of  creating a
+   new string.  The return value is a pair ``(nbytes, address)`` where *nbytes* is
+   the number of bytes received and *address* is the address of the socket sending
+   the data.  See the Unix manual page :manpage:`recv(2)` for the meaning of the
+   optional argument *flags*; it defaults to zero.  (The format of *address*
+   depends on the address family --- see above.)
+
+   .. versionadded:: 2.5
+
+
+.. method:: socket.recv_into(buffer[, nbytes[, flags]])
+
+   Receive up to *nbytes* bytes from the socket, storing the data into a buffer
+   rather than creating a new string.     If *nbytes* is not specified (or 0),
+   receive up to the size available in the given buffer. See the Unix manual page
+   :manpage:`recv(2)` for the meaning of the optional argument *flags*; it defaults
+   to zero.
+
+   .. versionadded:: 2.5
+
+
+.. method:: socket.send(string[, flags])
+
+   Send data to the socket.  The socket must be connected to a remote socket.  The
+   optional *flags* argument has the same meaning as for :meth:`recv` above.
+   Returns the number of bytes sent. Applications are responsible for checking that
+   all data has been sent; if only some of the data was transmitted, the
+   application needs to attempt delivery of the remaining data.
+
+
+.. method:: socket.sendall(string[, flags])
+
+   Send data to the socket.  The socket must be connected to a remote socket.  The
+   optional *flags* argument has the same meaning as for :meth:`recv` above.
+   Unlike :meth:`send`, this method continues to send data from *string* until
+   either all data has been sent or an error occurs.  ``None`` is returned on
+   success.  On error, an exception is raised, and there is no way to determine how
+   much data, if any, was successfully sent.
+
+
+.. method:: socket.sendto(string[, flags], address)
+
+   Send data to the socket.  The socket should not be connected to a remote socket,
+   since the destination socket is specified by *address*.  The optional *flags*
+   argument has the same meaning as for :meth:`recv` above.  Return the number of
+   bytes sent. (The format of *address* depends on the address family --- see
+   above.)
+
+
+.. method:: socket.setblocking(flag)
+
+   Set blocking or non-blocking mode of the socket: if *flag* is 0, the socket is
+   set to non-blocking, else to blocking mode.  Initially all sockets are in
+   blocking mode.  In non-blocking mode, if a :meth:`recv` call doesn't find any
+   data, or if a :meth:`send` call can't immediately dispose of the data, a
+   :exc:`error` exception is raised; in blocking mode, the calls block until they
+   can proceed. ``s.setblocking(0)`` is equivalent to ``s.settimeout(0)``;
+   ``s.setblocking(1)`` is equivalent to ``s.settimeout(None)``.
+
+
+.. method:: socket.settimeout(value)
+
+   Set a timeout on blocking socket operations.  The *value* argument can be a
+   nonnegative float expressing seconds, or ``None``. If a float is given,
+   subsequent socket operations will raise an :exc:`timeout` exception if the
+   timeout period *value* has elapsed before the operation has completed.  Setting
+   a timeout of ``None`` disables timeouts on socket operations.
+   ``s.settimeout(0.0)`` is equivalent to ``s.setblocking(0)``;
+   ``s.settimeout(None)`` is equivalent to ``s.setblocking(1)``.
+
+   .. versionadded:: 2.3
+
+
+.. method:: socket.gettimeout()
+
+   Return the timeout in floating seconds associated with socket operations, or
+   ``None`` if no timeout is set.  This reflects the last call to
+   :meth:`setblocking` or :meth:`settimeout`.
+
+   .. versionadded:: 2.3
+
+Some notes on socket blocking and timeouts: A socket object can be in one of
+three modes: blocking, non-blocking, or timeout.  Sockets are always created in
+blocking mode.  In blocking mode, operations block until complete.  In
+non-blocking mode, operations fail (with an error that is unfortunately
+system-dependent) if they cannot be completed immediately.  In timeout mode,
+operations fail if they cannot be completed within the timeout specified for the
+socket.  The :meth:`setblocking` method is simply a shorthand for certain
+:meth:`settimeout` calls.
+
+Timeout mode internally sets the socket in non-blocking mode.  The blocking and
+timeout modes are shared between file descriptors and socket objects that refer
+to the same network endpoint.  A consequence of this is that file objects
+returned by the :meth:`makefile` method must only be used when the socket is in
+blocking mode; in timeout or non-blocking mode file operations that cannot be
+completed immediately will fail.
+
+Note that the :meth:`connect` operation is subject to the timeout setting, and
+in general it is recommended to call :meth:`settimeout` before calling
+:meth:`connect`.
+
+
+.. method:: socket.setsockopt(level, optname, value)
+
+   .. index:: module: struct
+
+   Set the value of the given socket option (see the Unix manual page
+   :manpage:`setsockopt(2)`).  The needed symbolic constants are defined in the
+   :mod:`socket` module (:const:`SO_\*` etc.).  The value can be an integer or a
+   string representing a buffer.  In the latter case it is up to the caller to
+   ensure that the string contains the proper bits (see the optional built-in
+   module :mod:`struct` for a way to encode C structures as strings).
+
+
+.. method:: socket.shutdown(how)
+
+   Shut down one or both halves of the connection.  If *how* is :const:`SHUT_RD`,
+   further receives are disallowed.  If *how* is :const:`SHUT_WR`, further sends
+   are disallowed.  If *how* is :const:`SHUT_RDWR`, further sends and receives are
+   disallowed.
+
+Note that there are no methods :meth:`read` or :meth:`write`; use :meth:`recv`
+and :meth:`send` without *flags* argument instead.
+
+Socket objects also have these (read-only) attributes that correspond to the
+values given to the :class:`socket` constructor.
+
+
+.. attribute:: socket.family
+
+   The socket family.
+
+   .. versionadded:: 2.5
+
+
+.. attribute:: socket.type
+
+   The socket type.
+
+   .. versionadded:: 2.5
+
+
+.. attribute:: socket.proto
+
+   The socket protocol.
+
+   .. versionadded:: 2.5
+
+
+.. _socket-example:
+
+Example
+-------
+
+Here are four minimal example programs using the TCP/IP protocol: a server that
+echoes all data that it receives back (servicing only one client), and a client
+using it.  Note that a server must perform the sequence :func:`socket`,
+:meth:`bind`, :meth:`listen`, :meth:`accept` (possibly repeating the
+:meth:`accept` to service more than one client), while a client only needs the
+sequence :func:`socket`, :meth:`connect`.  Also note that the server does not
+:meth:`send`/:meth:`recv` on the  socket it is listening on but on the new
+socket returned by :meth:`accept`.
+
+The first two examples support IPv4 only. ::
+
+   # Echo server program
+   import socket
+
+   HOST = ''                 # Symbolic name meaning the local host
+   PORT = 50007              # Arbitrary non-privileged port
+   s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+   s.bind((HOST, PORT))
+   s.listen(1)
+   conn, addr = s.accept()
+   print 'Connected by', addr
+   while 1:
+       data = conn.recv(1024)
+       if not data: break
+       conn.send(data)
+   conn.close()
+
+::
+
+   # Echo client program
+   import socket
+
+   HOST = 'daring.cwi.nl'    # The remote host
+   PORT = 50007              # The same port as used by the server
+   s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+   s.connect((HOST, PORT))
+   s.send('Hello, world')
+   data = s.recv(1024)
+   s.close()
+   print 'Received', repr(data)
+
+The next two examples are identical to the above two, but support both IPv4 and
+IPv6. The server side will listen to the first address family available (it
+should listen to both instead). On most of IPv6-ready systems, IPv6 will take
+precedence and the server may not accept IPv4 traffic. The client side will try
+to connect to the all addresses returned as a result of the name resolution, and
+sends traffic to the first one connected successfully. ::
+
+   # Echo server program
+   import socket
+   import sys
+
+   HOST = ''                 # Symbolic name meaning the local host
+   PORT = 50007              # Arbitrary non-privileged port
+   s = None
+   for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC, socket.SOCK_STREAM, 0, socket.AI_PASSIVE):
+       af, socktype, proto, canonname, sa = res
+       try:
+   	s = socket.socket(af, socktype, proto)
+       except socket.error, msg:
+   	s = None
+   	continue
+       try:
+   	s.bind(sa)
+   	s.listen(1)
+       except socket.error, msg:
+   	s.close()
+   	s = None
+   	continue
+       break
+   if s is None:
+       print 'could not open socket'
+       sys.exit(1)
+   conn, addr = s.accept()
+   print 'Connected by', addr
+   while 1:
+       data = conn.recv(1024)
+       if not data: break
+       conn.send(data)
+   conn.close()
+
+::
+
+   # Echo client program
+   import socket
+   import sys
+
+   HOST = 'daring.cwi.nl'    # The remote host
+   PORT = 50007              # The same port as used by the server
+   s = None
+   for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC, socket.SOCK_STREAM):
+       af, socktype, proto, canonname, sa = res
+       try:
+   	s = socket.socket(af, socktype, proto)
+       except socket.error, msg:
+   	s = None
+   	continue
+       try:
+   	s.connect(sa)
+       except socket.error, msg:
+   	s.close()
+   	s = None
+   	continue
+       break
+   if s is None:
+       print 'could not open socket'
+       sys.exit(1)
+   s.send('Hello, world')
+   data = s.recv(1024)
+   s.close()
+   print 'Received', repr(data)
+
+   
+The last example shows how to write a very simple network sniffer with raw
+sockets on Windows. The example requires administrator priviliges to modify
+the interface::
+
+   import socket
+
+   # the public network interface
+   HOST = socket.gethostbyname(socket.gethostname())
+   
+   # create a raw socket and bind it to the public interface
+   s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_IP)
+   s.bind((HOST, 0))
+   
+   # Include IP headers
+   s.setsockopt(socket.IPPROTO_IP, socket.IP_HDRINCL, 1)
+   
+   # receive all packages
+   s.ioctl(socket.SIO_RCVALL, socket.RCVALL_ON)
+   
+   # receive a package
+   print s.recvfrom(65565)
+   
+   # disabled promiscous mode
+   s.ioctl(socket.SIO_RCVALL, socket.RCVALL_OFF)