--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/symbian-qemu-0.9.1-12/python-2.6.1/Doc/library/socket.rst Fri Jul 31 15:01:17 2009 +0100
@@ -0,0 +1,936 @@
+
+: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:`3493` 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``.
+
+.. versionadded:: 2.6
+ Linux-only support for TIPC is also available using the :const:`AF_TIPC`
+ address family. TIPC is an open, non-IP based networked protocol designed
+ for use in clustered computer environments. Addresses are represented by a
+ tuple, and the fields depend on the address type. The general tuple form is
+ ``(addr_type, v1, v2, v3 [, scope])``, where:
+
+ - *addr_type* is one of TIPC_ADDR_NAMESEQ, TIPC_ADDR_NAME, or
+ TIPC_ADDR_ID.
+ - *scope* is one of TIPC_ZONE_SCOPE, TIPC_CLUSTER_SCOPE, and
+ TIPC_NODE_SCOPE.
+ - If *addr_type* is TIPC_ADDR_NAME, then *v1* is the server type, *v2* is
+ the port identifier, and *v3* should be 0.
+
+ If *addr_type* is TIPC_ADDR_NAMESEQ, then *v1* is the server type, *v2*
+ is the lower port number, and *v3* is the upper port number.
+
+ If *addr_type* is TIPC_ADDR_ID, then *v1* is the node, *v2* is the
+ reference, and *v3* should be set to 0.
+
+
+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:: TIPC_*
+
+ TIPC related constants, matching the ones exported by the C socket API. See
+ the TIPC documentation for more information.
+
+ .. 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])
+
+ Convenience function. Connect to *address* (a 2-tuple ``(host, port)``),
+ and return the socket object. Passing the optional *timeout* parameter will
+ set the timeout on the socket instance before attempting to connect. If no
+ *timeout* is supplied, the global default timeout setting returned by
+ :func:`getdefaulttimeout` 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 arguments for creating the corresponding socket. *host* is a domain
+ name, a string representation of an IPv4/v6 address or ``None``. *port* is a string
+ service name such as ``'http'``, a numeric port number or ``None``.
+ The rest of the arguments are optional and must be numeric if specified.
+ By passing ``None`` as the value of *host* and *port*, , 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 integers 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, followed by 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 all available interfaces
+ 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 = None # Symbolic name meaning all available interfaces
+ 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 privileges 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 promiscuous mode
+ s.ioctl(socket.SIO_RCVALL, socket.RCVALL_OFF)