socket — Low-level networking interface低层网络接口

Source code: Lib/socket.py

This module provides access to the BSD socket interface. 此模块提供对BSD套接字接口的访问。It is available on all modern Unix systems, Windows, MacOS, and probably additional platforms.它可以在所有现代Unix系统、Windows、MacOS以及可能的其他平台上使用。

Note

Some behavior may be platform dependent, since calls are made to the operating system socket APIs.有些行为可能依赖于平台，因为调用操作系统套接字API。

The Python interface is a straightforward transliteration of the Unix system call and library interface for sockets to Python’s object-oriented style: the socket() function returns a socket object whose methods implement the various socket system calls. Python接口是Unix系统调用和socket库接口对Python面向对象风格的直接音译：socket()函数返回一个socket对象，其方法实现各种socket系统调用。Parameter types are somewhat higher-level than in the C interface: as with read() and write() operations on Python files, buffer allocation on receive operations is automatic, and buffer length is implicit on send operations.参数类型的级别比C接口稍高：与Python文件上的read()和write()操作一样，接收操作上的缓冲区分配是自动的，发送操作上的缓存长度是隐式的。

See also参阅

Module 模块socketserver

Classes that simplify writing network servers.简化网络服务器编写的类。

Module 模块ssl

A TLS/SSL wrapper for socket objects.套接字对象的TLS/SSL包装器。

Socket familiesSocket家族

Depending on the system and the build options, various socket families are supported by this module.根据系统和构建选项，此模块支持各种插座系列。

The address format required by a particular socket object is automatically selected based on the address family specified when the socket object was created. 根据创建套接字对象时指定的地址族，自动选择特定套接字对象所需的地址格式。Socket addresses are represented as follows:套接字地址表示如下：

  • The address of an AF_UNIX socket bound to a file system node is represented as a string, using the file system encoding and the 'surrogateescape' error handler (see PEP 383). 绑定到文件系统节点的AF_UNIX套接字的地址表示为字符串，使用文件系统编码'surrogateescape'和错误处理程序（请参阅PEP 383）。An address in Linux’s abstract namespace is returned as a bytes-like object with an initial null byte; note that sockets in this namespace can communicate with normal file system sockets, so programs intended to run on Linux may need to deal with both types of address. Linux抽象名称空间中的地址以类字节对象的形式返回，初始为空字节；请注意，此名称空间中的套接字可以与普通文件系统套接字通信，因此打算在Linux上运行的程序可能需要处理这两种类型的地址。A string or bytes-like object can be used for either type of address when passing it as an argument.作为参数传递时，字符串或类似字节的对象可用于任一类型的地址。

    Changed in version 3.3:版本3.3中更改： Previously, AF_UNIX socket paths were assumed to use UTF-8 encoding.以前，假设AF_UNIX套接字路径使用UTF-8编码。

    Changed in version 3.5:版本3.5中更改： Writable bytes-like object is now accepted.现在接受可写的类字节对象。

  • A pair (host, port) is used for the 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 integer.一对(host, port)用于AF_INET地址系列，其中host是一个字符串，表示internet域符号中的主机名，如'daring.cwi.nl'，或IPv4地址，如'100.50.200.5'，port是一个整数。

    • For IPv4 addresses, two special forms are accepted instead of a host address: '' represents INADDR_ANY, which is used to bind to all interfaces, and the string '<broadcast>' represents INADDR_BROADCAST. 对于IPv4地址，接受两种特殊形式而不是主机地址：''表示INADDR_ANY，它用来绑定到所有的接口，而字符串'<broadcast>'代表INADDR_BROADCAST。This behavior is not compatible with IPv6, therefore, you may want to avoid these if you intend to support IPv6 with your Python programs.这种行为与IPv6不兼容，因此，如果您打算用Python程序支持IPv6，您可能希望避免这些行为。

  • For AF_INET6 address family, a four-tuple (host, port, flowinfo, scope_id) is used, where flowinfo and scope_id represent the sin6_flowinfo and sin6_scope_id members in struct sockaddr_in6 in C. For socket module methods, flowinfo and scope_id can be omitted just for backward compatibility. Note, however, omission of scope_id can cause problems in manipulating scoped IPv6 addresses.

    Changed in version 3.7:版本3.7中更改： For multicast addresses (with scope_id meaningful) address may not contain %scope_id (or zone id) part. This information is superfluous and may be safely omitted (recommended).

  • AF_NETLINK sockets are represented as pairs (pid, groups).

  • Linux-only support for TIPC is available using the 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.

  • A tuple (interface, ) is used for the AF_CAN address family, where interface is a string representing a network interface name like 'can0'. The network interface name '' can be used to receive packets from all network interfaces of this family.

    • CAN_ISOTP protocol require a tuple (interface, rx_addr, tx_addr) where both additional parameters are unsigned long integer that represent a CAN identifier (standard or extended).

    • CAN_J1939 protocol require a tuple (interface, name, pgn, addr) where additional parameters are 64-bit unsigned integer representing the ECU name, a 32-bit unsigned integer representing the Parameter Group Number (PGN), and an 8-bit integer representing the address.

  • A string or a tuple (id, unit) is used for the SYSPROTO_CONTROL protocol of the PF_SYSTEM family. 字符串或元组(id, unit)用于PF_SYSTEM系列的SYSPROTO_CONTROL协议。The string is the name of a kernel control using a dynamically-assigned ID. 字符串是使用动态分配的ID的内核控件的名称。The tuple can be used if ID and unit number of the kernel control are known or if a registered ID is used.如果内核控件的ID和单元号已知，或者使用了注册的ID，则可以使用元组。

    New in version 3.3.版本3.3中新增。

  • AF_BLUETOOTH supports the following protocols and address formats:支持以下协议和地址格式：

    • BTPROTO_L2CAP accepts (bdaddr, psm) where bdaddr is the Bluetooth address as a string and psm is an integer.

    • BTPROTO_RFCOMM accepts (bdaddr, channel) where bdaddr is the Bluetooth address as a string and channel is an integer.

    • BTPROTO_HCI accepts (device_id,) where device_id is either an integer or a string with the Bluetooth address of the interface. (This depends on your OS; NetBSD and DragonFlyBSD expect a Bluetooth address while everything else expects an integer.)（这取决于您的操作系统；NetBSD和DragonFlyBSD需要一个蓝牙地址，而其他的都需要一个整数。）

      Changed in version 3.2:版本3.2中更改： NetBSD and DragonFlyBSD support added.

    • BTPROTO_SCO accepts bdaddr where bdaddr is a bytes object containing the Bluetooth address in a string format. (ex. b'12:23:34:45:56:67') This protocol is not supported under FreeBSD.FreeBSD不支持此协议。

  • AF_ALG is a Linux-only socket based interface to Kernel cryptography. 是一个仅限Linux的基于套接字的内核加密接口。An algorithm socket is configured with a tuple of two to four elements (type, name [, feat [, mask]]), where:算法套接字配置有两到四个元素(type, name [, feat [, mask]])的元组，其中：

    • type is the algorithm type as string, e.g. aead, hash, skcipher or rng.

    • name is the algorithm name and operation mode as string, e.g. sha256, hmac(sha256), cbc(aes) or drbg_nopr_ctr_aes256.

    • feat and mask are unsigned 32bit integers.

    Availability: Linux 2.6.38, some algorithm types require more recent Kernels.

    New in version 3.6.版本3.6中新增。

  • AF_VSOCK allows communication between virtual machines and their hosts. 允许虚拟机与其主机之间的通信。The sockets are represented as a (CID, port) tuple where the context ID or CID and port are integers.套接字表示为(CID, port)元组，其中上下文ID或CID和端口是整数。

    Availability: Linux >= 4.8 QEMU >= 2.8 ESX >= 4.0 ESX Workstation >= 6.5.

    New in version 3.7.版本3.7中新增。

  • AF_PACKET is a low-level interface directly to network devices. 是直接到网络设备的低级接口。The packets are represented by the tuple (ifname, proto[, pkttype[, hatype[, addr]]]) where:数据包由元组(ifname, proto[, pkttype[, hatype[, addr]]])表示，其中：

    • ifname - String specifying the device name.指定设备名称的字符串。

    • proto - An in network-byte-order integer specifying the Ethernet protocol number.指定以太网协议号的网络内字节顺序整数。

    • pkttype - Optional integer specifying the packet type:指定数据包类型的可选整数：

      • PACKET_HOST (the default) - Packet addressed to the local host.发往本地主机的数据包。

      • PACKET_BROADCAST - Physical-layer broadcast packet.物理层广播包。

      • PACKET_MULTIHOST - Packet sent to a physical-layer multicast address.发送到物理层多播地址的数据包。

      • PACKET_OTHERHOST - Packet to some other host that has been caught by a device driver in promiscuous mode.发送到其他主机的数据包已被设备驱动程序以混乱模式捕获。

      • PACKET_OUTGOING - Packet originating from the local host that is looped back to a packet socket.从本地主机发出的数据包，被循环回数据包套接字。

    • hatype - Optional integer specifying the ARP hardware address type.指定ARP硬件地址类型的可选整数。

    • addr - Optional bytes-like object specifying the hardware physical address, whose interpretation depends on the device.可选字节，如指定硬件物理地址的对象，其解释取决于设备。

    Availability: Linux >= 2.2.

  • AF_QIPCRTR is a Linux-only socket based interface for communicating with services running on co-processors in Qualcomm platforms. 是一个基于Linux的套接字接口，用于与高通平台中协同处理器上运行的服务进行通信。The address family is represented as a (node, port) tuple where the node and port are non-negative integers.地址族表示为(node, port)元组，其中node和port为非负整数。

    Availability: Linux >= 4.7.

    New in version 3.8.版本3.8中新增。

  • IPPROTO_UDPLITE is a variant of UDP which allows you to specify what portion of a packet is covered with the checksum. 是UDP的一种变体，允许您指定校验和覆盖了数据包的哪一部分。It adds two socket options that you can change. 它添加了两个可以更改的套接字选项。self.setsockopt(IPPROTO_UDPLITE, UDPLITE_SEND_CSCOV, length) will change what portion of outgoing packets are covered by the checksum and self.setsockopt(IPPROTO_UDPLITE, UDPLITE_RECV_CSCOV, length) will filter out packets which cover too little of their data. In both cases length should be in range(8, 2**16, 8).

    Such a socket should be constructed with socket(AF_INET, SOCK_DGRAM, IPPROTO_UDPLITE) for IPv4 or socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDPLITE) for IPv6.

    Availability: Linux >= 2.6.20, FreeBSD >= 10.1-RELEASE

    New in version 3.9.版本3.9中新增。

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.

All errors raise exceptions. The normal exceptions for invalid argument types and out-of-memory conditions can be raised; starting from Python 3.3, errors related to socket or address semantics raise OSError or one of its subclasses (they used to raise socket.error).

Non-blocking mode is supported through setblocking(). A generalization of this based on timeouts is supported through settimeout().

Module contents模块内容

The module socket exports the following elements.

Exceptions例外情况

exceptionsocket.error

A deprecated alias of OSError.OSError的不推荐的别名。

Changed in version 3.3:版本3.3中更改： Following PEP 3151, this class was made an alias of OSError.

exceptionsocket.herror

A subclass of OSError, this exception is raised for address-related errors, i.e. for functions that use h_errno in the POSIX C API, including gethostbyname_ex() and gethostbyaddr(). The accompanying value is a pair (h_errno, string) representing an error returned by a library call. h_errno is a numeric value, while string represents the description of h_errno, as returned by the hstrerror() C function.

Changed in version 3.3:版本3.3中更改： This class was made a subclass of OSError.

exceptionsocket.gaierror

A subclass of OSError, this exception is raised for address-related errors by getaddrinfo() and 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 gai_strerror() C function. The numeric error value will match one of the EAI_* constants defined in this module.

Changed in version 3.3:版本3.3中更改： This class was made a subclass of OSError.

exceptionsocket.timeout

A deprecated alias of TimeoutError.

A subclass of OSError, this exception is raised when a timeout occurs on a socket which has had timeouts enabled via a prior call to settimeout() (or implicitly through setdefaulttimeout()). The accompanying value is a string whose value is currently always “timed out”.伴随的值是一个字符串，其值当前总是“超时”。

Changed in version 3.3:版本3.3中更改： This class was made a subclass of OSError.

Changed in version 3.10:版本3.10中更改： This class was made an alias of TimeoutError.

Constants常量

The AF_* and SOCK_* constants are now AddressFamily and SocketKind IntEnum collections.AF_*和SOCK_*常量现在是AddressFamily和SocketKind IntEnum集合。

New in version 3.4.版本3.4中新增。

socket.AF_UNIX
socket.AF_INET
socket.AF_INET6

These constants represent the address (and protocol) families, used for the first argument to socket(). If the AF_UNIX constant is not defined then this protocol is unsupported. More constants may be available depending on the system.

socket.SOCK_STREAM
socket.SOCK_DGRAM
socket.SOCK_RAW
socket.SOCK_RDM
socket.SOCK_SEQPACKET

These constants represent the socket types, used for the second argument to socket(). 这些常量表示套接字类型，用于socket()的第二个参数。More constants may be available depending on the system. 根据系统的不同，可以使用更多的常量。(Only SOCK_STREAM and SOCK_DGRAM appear to be generally useful.)（通常只有SOCK_STREAM和SOCK_DGRAM才有用。）

socket.SOCK_CLOEXEC
socket.SOCK_NONBLOCK

These two constants, if defined, can be combined with the socket types and allow you to set some flags atomically (thus avoiding possible race conditions and the need for separate calls).这两个常量（如果定义了）可以与套接字类型组合，并允许您原子地设置一些标志（从而避免可能的竞争条件和单独调用的需要）。

See also

Secure File Descriptor Handling for a more thorough explanation.以获得更详细的解释。

Availability: Linux >= 2.6.27.

New in version 3.2.版本3.2中新增。

SO_*
socket.SOMAXCONN
MSG_*
SOL_*
SCM_*
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. Unix文档中关于套接字和/或IP协议的许多常量也在套接字模块中定义。They are generally used in arguments to the setsockopt() and getsockopt() methods of socket objects. 它们通常用于套接字对象的setsockopt()和getsockopt()方法的参数中。In most cases, only those symbols that are defined in the Unix header files are defined; for a few symbols, default values are provided.在大多数情况下，只定义Unix头文件中定义的符号；对于少数符号，提供了默认值。

Changed in version 3.6:版本3.6中更改： SO_DOMAIN, SO_PROTOCOL, SO_PEERSEC, SO_PASSSEC, TCP_USER_TIMEOUT, TCP_CONGESTION were added.

Changed in version 3.6.5:版本3.6.5中更改： On Windows, TCP_FASTOPEN, TCP_KEEPCNT appear if run-time Windows supports.在Windows上，如果运行时Windows支持，则会显示TCP_FASTOPEN、TCP_KEEPCNT。

Changed in version 3.7:版本3.7中更改： TCP_NOTSENT_LOWAT was added.

On Windows, TCP_KEEPIDLE, TCP_KEEPINTVL appear if run-time Windows supports.在Windows上，如果运行时Windows支持，则会显示TCP_KEEPIDLE、TCP_KEEPINTVL。

Changed in version 3.10:版本3.10中更改： IP_RECVTOS was added. Added TCP_KEEPALIVE. On MacOS this constant can be used in the same way that TCP_KEEPIDLE is used on Linux.在MacOS上，此常数的使用方式与在Linux上使用TCP_KEEPIDLE的方式相同。

socket.AF_CAN
socket.PF_CAN
SOL_CAN_*
CAN_*

Many constants of these forms, documented in the Linux documentation, are also defined in the socket module.Linux文档中记录的这些形式的许多常量也在套接字模块中定义。

Availability: Linux >= 2.6.25.

New in version 3.3.版本3.3中新增。

socket.CAN_BCM
CAN_BCM_*

CAN_BCM, in the CAN protocol family, is the broadcast manager (BCM) protocol. CAN协议族中的CAN_BCM是广播管理器（BCM）协议。Broadcast manager constants, documented in the Linux documentation, are also defined in the socket module.Linux文档中记录的广播管理器常量也在套接字模块中定义。

Availability: Linux >= 2.6.25.

Note

The CAN_BCM_CAN_FD_FRAME flag is only available on Linux >= 4.8.

New in version 3.4.版本3.4中新增。

socket.CAN_RAW_FD_FRAMES

Enables CAN FD support in a CAN_RAW socket. 在CAN_RAW插座中启用CAN FD支持。This is disabled by default. 这在默认情况下是禁用的。This allows your application to send both CAN and CAN FD frames; however, you must accept both CAN and CAN FD frames when reading from the socket.这允许您的应用程序发送CAN和CAN FD帧；但是，从套接字读取时，必须同时接受CAN和CAN FD帧。

This constant is documented in the Linux documentation.Linux文档中记录了此常数。

Availability: Linux >= 3.6.

New in version 3.5.版本3.5中新增。

socket.CAN_RAW_JOIN_FILTERS

Joins the applied CAN filters such that only CAN frames that match all given CAN filters are passed to user space.连接应用的CAN筛选器，以便仅将与所有给定CAN过滤器匹配的CAN帧传递到用户空间。

This constant is documented in the Linux documentation.Linux文档中记录了此常数。

Availability: Linux >= 4.1.

New in version 3.9.版本3.9中新增。

socket.CAN_ISOTP

CAN_ISOTP, in the CAN protocol family, is the ISO-TP (ISO 15765-2) protocol. CAN协议族中的CAN_ISOTP是ISO-TP(ISO 15765-2）协议。ISO-TP constants, documented in the Linux documentation.ISO-TP常量，记录在Linux文档中。

Availability: Linux >= 2.6.25.

New in version 3.7.版本3.7中新增。

socket.CAN_J1939

CAN_J1939, in the CAN protocol family, is the SAE J1939 protocol. J1939 constants, documented in the Linux documentation.CAN协议族中的CAN_J1939是SAE J1939协议。J1939常量，记录在Linux文档中。

Availability: Linux >= 5.4.

New in version 3.9.版本3.9中新增。

socket.AF_PACKET
socket.PF_PACKET
PACKET_*

Many constants of these forms, documented in the Linux documentation, are also defined in the socket module.Linux文档中记录的这些形式的许多常量也在套接字模块中定义。

Availability: Linux >= 2.2.

socket.AF_RDS
socket.PF_RDS
socket.SOL_RDS
RDS_*

Many constants of these forms, documented in the Linux documentation, are also defined in the socket module.Linux文档中记录的这些形式的许多常量也在套接字模块中定义。

Availability: Linux >= 2.6.30.

New in version 3.3.版本3.3中新增。

socket.SIO_RCVALL
socket.SIO_KEEPALIVE_VALS
socket.SIO_LOOPBACK_FAST_PATH
RCVALL_*

Constants for Windows’ WSAIoctl(). Windows的WSAIoctl()的常量。The constants are used as arguments to the ioctl() method of socket objects.常量用作套接字对象的ioctl()方法的参数。

Changed in version 3.6:版本3.6中更改： SIO_LOOPBACK_FAST_PATH was added.已添加。

TIPC_*

TIPC related constants, matching the ones exported by the C socket API. TIPC相关常量，与C套接字API导出的常量匹配。See the TIPC documentation for more information.有关更多信息，请参阅TIPC文档。

socket.AF_ALG
socket.SOL_ALG
ALG_*

Constants for Linux Kernel cryptography.Linux内核加密的常量。

Availability: Linux >= 2.6.38.

New in version 3.6.版本3.6中新增。

socket.AF_VSOCK
socket.IOCTL_VM_SOCKETS_GET_LOCAL_CID
VMADDR*
SO_VM*

Constants for Linux host/guest communication.Linux主机/客户机通信的常数。

Availability: Linux >= 4.8.

New in version 3.7.版本3.7中新增。

Availability: BSD, macOS.

New in version 3.4.版本3.4中新增。

socket.has_ipv6

This constant contains a boolean value which indicates if IPv6 is supported on this platform.此常量包含一个布尔值，指示此平台是否支持IPv6。

socket.BDADDR_ANY
socket.BDADDR_LOCAL

These are string constants containing Bluetooth addresses with special meanings. 这些是包含具有特殊含义的蓝牙地址的字符串常量。For example, BDADDR_ANY can be used to indicate any address when specifying the binding socket with BTPROTO_RFCOMM.

socket.HCI_FILTER
socket.HCI_TIME_STAMP
socket.HCI_DATA_DIR

For use with BTPROTO_HCI. HCI_FILTER is not available for NetBSD or DragonFlyBSD. HCI_TIME_STAMP and HCI_DATA_DIR are not available for FreeBSD, NetBSD, or DragonFlyBSD.

socket.AF_QIPCRTR

Constant for Qualcomm’s IPC router protocol, used to communicate with service providing remote processors.高通公司IPC路由器协议的常量，用于与提供服务的远程处理器通信。

Availability: Linux >= 4.7.

Functions功能

Creating sockets创建套接字

The following functions all create socket objects.以下函数都创建套接字对象。

classsocket.socket(family=AF_INET, type=SOCK_STREAM, proto=0, fileno=None)

Create a new socket using the given address family, socket type and protocol number. The address family should be AF_INET (the default), AF_INET6, AF_UNIX, AF_CAN, AF_PACKET, or AF_RDS. The socket type should be SOCK_STREAM (the default), SOCK_DGRAM, SOCK_RAW or perhaps one of the other SOCK_ constants. The protocol number is usually zero and may be omitted or in the case where the address family is AF_CAN the protocol should be one of CAN_RAW, CAN_BCM, CAN_ISOTP or CAN_J1939.

If fileno is specified, the values for family, type, and proto are auto-detected from the specified file descriptor. Auto-detection can be overruled by calling the function with explicit family, type, or proto arguments. This only affects how Python represents e.g. the return value of socket.getpeername() but not the actual OS resource. Unlike socket.fromfd(), fileno will return the same socket and not a duplicate. This may help close a detached socket using socket.close().

The newly created socket is non-inheritable.新创建的套接字不可继承。

Raises an auditing event socket.__new__ with arguments self, family, type, protocol.

Changed in version 3.3:版本3.3中更改： The AF_CAN family was added. The AF_RDS family was added.

Changed in version 3.4:版本3.4中更改： The CAN_BCM protocol was added.

Changed in version 3.4:版本3.4中更改： The returned socket is now non-inheritable.返回的套接字现在不可继承。

Changed in version 3.7:版本3.7中更改： The CAN_ISOTP protocol was added.

Changed in version 3.7:版本3.7中更改： When SOCK_NONBLOCK or SOCK_CLOEXEC bit flags are applied to type they are cleared, and socket.type will not reflect them. They are still passed to the underlying system socket() call. Therefore,

sock = socket.socket(
    socket.AF_INET,
    socket.SOCK_STREAM | socket.SOCK_NONBLOCK)

will still create a non-blocking socket on OSes that support SOCK_NONBLOCK, but sock.type will be set to socket.SOCK_STREAM.

Changed in version 3.9:版本3.9中更改： The CAN_J1939 protocol was added.

Changed in version 3.10:版本3.10中更改： The IPPROTO_MPTCP protocol was added.

socket.socketpair([family[, type[, proto]]])

Build a pair of connected socket objects using the given address family, socket type, and protocol number. 使用给定的地址族、套接字类型和协议号构建一对连接的套接字对象。Address family, socket type, and protocol number are as for the socket() function above. 地址族、套接字类型和协议号与上面的socket()函数相同。The default family is AF_UNIX if defined on the platform; otherwise, the default is AF_INET.如果在平台上定义，则默认族为AF_UNIX；否则，默认值为AF_INET。

The newly created sockets are non-inheritable.新创建的套接字是不可继承的。

Changed in version 3.2:版本3.2中更改： The returned socket objects now support the whole socket API, rather than a subset.返回的套接字对象现在支持整个套接字API，而不是子集。

Changed in version 3.4:版本3.4中更改： The returned sockets are now non-inheritable.返回的套接字现在不可继承。

Changed in version 3.5:版本3.5中更改： Windows support added.添加了Windows支持。

socket.create_connection(address[, timeout[, source_address]])

Connect to a TCP service listening on the internet address (a 2-tuple (host, port)), and return the socket object. This is a higher-level function than socket.connect(): if host is a non-numeric hostname, it will try to resolve it for both AF_INET and AF_INET6, and then try to connect to all possible addresses in turn until a connection succeeds. This makes it easy to write clients that are compatible to both IPv4 and IPv6.这使得编写兼容IPv4和IPv6的客户端变得容易。

Passing the optional timeout parameter will set the timeout on the socket instance before attempting to connect. 传递可选的超时参数将在尝试连接之前设置套接字实例的超时。If no timeout is supplied, the global default timeout setting returned by getdefaulttimeout() is used.

If supplied, source_address must be a 2-tuple (host, port) for the socket to bind to as its source address before connecting. If host or port are ‘’ or 0 respectively the OS default behavior will be used.

Changed in version 3.2:版本3.2中更改： source_address was added.

socket.create_server(address, *, family=AF_INET, backlog=None, reuse_port=False, dualstack_ipv6=False)

Convenience function which creates a TCP socket bound to address (a 2-tuple (host, port)) and return the socket object.

family should be either AF_INET or AF_INET6. backlog is the queue size passed to socket.listen(); when 0 a default reasonable value is chosen. reuse_port dictates whether to set the SO_REUSEPORT socket option.

If dualstack_ipv6 is true and the platform supports it the socket will be able to accept both IPv4 and IPv6 connections, else it will raise ValueError. Most POSIX platforms and Windows are supposed to support this functionality. When this functionality is enabled the address returned by socket.getpeername() when an IPv4 connection occurs will be an IPv6 address represented as an IPv4-mapped IPv6 address. If dualstack_ipv6 is false it will explicitly disable this functionality on platforms that enable it by default (e.g. Linux). This parameter can be used in conjunction with has_dualstack_ipv6():

import socket
addr = ("", 8080)  # all interfaces, port 8080
if socket.has_dualstack_ipv6():
    s = socket.create_server(addr, family=socket.AF_INET6, dualstack_ipv6=True)
else:
    s = socket.create_server(addr)

Note

On POSIX platforms the SO_REUSEADDR socket option is set in order to immediately reuse previous sockets which were bound on the same address and remained in TIME_WAIT state.在POSIX平台上，设置了SO_REUSEADDR套接字选项，以便立即重用绑定在同一address并保持TIME_WAIT状态的先前套接字。

New in version 3.8.版本3.8中新增。

socket.has_dualstack_ipv6()

Return True if the platform supports creating a TCP socket which can handle both IPv4 and IPv6 connections.如果平台支持创建可以处理IPv4和IPv6连接的TCP套接字，则返回True。

New in version 3.8.版本3.8中新增。

socket.fromfd(fd, family, type, proto=0)

Duplicate the file descriptor fd (an integer as returned by a file object’s fileno() method) and build a socket object from the result. 复制文件描述符fd（文件对象的fileno()方法返回的整数），并根据结果构建套接字对象。Address family, socket type and protocol number are as for the socket() function above. 地址族、套接字类型和协议号与上面的socket()函数相同。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. 文件描述符应引用套接字，但未选中此选项-如果文件描述符无效，则对对象的后续操作可能会失败。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). 这个函数很少需要，但可以用于获取或设置套接字选项，该套接字作为标准输入或输出传递给程序（例如由Unix inet守护程序启动的服务器）。The socket is assumed to be in blocking mode.假定套接字处于阻塞模式。

The newly created socket is non-inheritable.新创建的套接字不可继承。

Changed in version 3.4:版本3.4中更改： The returned socket is now non-inheritable.返回的套接字现在不可继承。

socket.fromshare(data)

Instantiate a socket from data obtained from the socket.share() method. 根据从socket.share()方法获得的数据实例化套接字。The socket is assumed to be in blocking mode.假定套接字处于阻塞模式。

Availability: Windows.

New in version 3.3.版本3.3中新增。

socket.SocketType

This is a Python type object that represents the socket object type. 这是一个表示套接字对象类型的Python类型对象。It is the same as type(socket(...)).它与type(socket(...))相同。

Other functions其他功能

The socket module also offers various network-related services:socket模块还提供各种网络相关服务：

socket.close(fd)

Close a socket file descriptor. This is like os.close(), but for sockets. On some platforms (most noticeable Windows) os.close() does not work for socket file descriptors.

New in version 3.7.版本3.7中新增。

socket.getaddrinfo(host, port, family=0, type=0, proto=0, flags=0)

Translate the host/port argument into a sequence of 5-tuples that contain all the necessary arguments for creating a socket connected to that service. 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. By passing None as the value of host and port, you can pass NULL to the underlying C API.

The family, type and proto arguments can be optionally specified in order to narrow the list of addresses returned. Passing zero as a value for each of these arguments selects the full range of results. The flags argument can be one or several of the AI_* constants, and will influence how results are computed and returned. For example, AI_NUMERICHOST will disable domain name resolution and will raise an error if host is a domain name.

The function returns a list of 5-tuples with the following structure:该函数返回具有以下结构的5元组列表：

(family, type, proto, canonname, sockaddr)

In these tuples, family, type, proto are all integers and are meant to be passed to the socket() function. 在这些元组中，family、type、proto都是整数，并且要传递给socket()函数。canonname will be a string representing the canonical name of the host if AI_CANONNAME is part of the flags argument; else canonname will be empty. sockaddr is a tuple describing a socket address, whose format depends on the returned family (a (address, port) 2-tuple for AF_INET, a (address, port, flowinfo, scope_id) 4-tuple for AF_INET6), and is meant to be passed to the socket.connect() method.

Raises an auditing event socket.getaddrinfo with arguments host, port, family, type, protocol.

The following example fetches address information for a hypothetical TCP connection to example.org on port 80 (results may differ on your system if IPv6 isn’t enabled):

>>> socket.getaddrinfo("example.org", 80, proto=socket.IPPROTO_TCP)
[(<AddressFamily.AF_INET6: 10>, <AddressFamily.SOCK_STREAM: 1>,
 6, '', ('2606:2800:220:1:248:1893:25c8:1946', 80, 0, 0)),
 (<AddressFamily.AF_INET: 2>, <AddressFamily.SOCK_STREAM: 1>,
 6, '', ('93.184.216.34', 80))]

Changed in version 3.2:版本3.2中更改： parameters can now be passed using keyword arguments.现在可以使用关键字参数传递参数。

Changed in version 3.7:版本3.7中更改： for IPv6 multicast addresses, string representing an address will not contain %scope_id part.对于IPv6多播地址，表示地址的字符串将不包含%scope_id部分。

socket.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 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 and name was provided, it is returned unchanged. If name was empty or equal to '0.0.0.0', the hostname from gethostname() is returned.

socket.gethostbyname(hostname)

Translate a host name to IPv4 address format. 将主机名转换为IPv4地址格式。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. 如果主机名本身是IPv4地址，则返回不变。See gethostbyname_ex() for a more complete interface. gethostbyname() does not support IPv6 name resolution, and getaddrinfo() should be used instead for IPv4/v6 dual stack support.

Raises an auditing event socket.gethostbyname with argument hostname.

socket.gethostbyname_ex(hostname)

Translate a host name to IPv4 address format, extended interface. 将主机名转换为IPv4地址格式，扩展接口。Return a triple (hostname, aliaslist, ipaddrlist) where hostname is the host’s primary host name, 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). gethostbyname_ex() does not support IPv6 name resolution, and getaddrinfo() should be used instead for IPv4/v6 dual stack support.

Raises an auditing event socket.gethostbyname with argument hostname.

socket.gethostname()

Return a string containing the hostname of the machine where the Python interpreter is currently executing.

Raises an auditing event socket.gethostname with no arguments.

Note: gethostname() doesn’t always return the fully qualified domain name; use getfqdn() for that.

socket.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 getfqdn(). gethostbyaddr() supports both IPv4 and IPv6.

Raises an auditing event socket.gethostbyaddr with argument ip_address.

socket.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.

For IPv6 addresses, %scope_id is appended to the host part if sockaddr contains meaningful scope_id. Usually this happens for multicast addresses.

For more information about flags you can consult getnameinfo(3).

Raises an auditing event socket.getnameinfo with argument sockaddr.

socket.getprotobyname(protocolname)

Translate an internet protocol name (for example, 'icmp') to a constant suitable for passing as the (optional) third argument to the socket() function. This is usually only needed for sockets opened in “raw” mode (SOCK_RAW); for the normal socket modes, the correct protocol is chosen automatically if the protocol is omitted or zero.

socket.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.

Raises an auditing event socket.getservbyname with arguments servicename, protocolname.

socket.getservbyport(port[, protocolname])

Translate an internet port number and protocol name to a service name for that service. 将互联网端口号和协议名称转换为该服务的服务名称。The optional protocol name, if given, should be 'tcp' or 'udp', otherwise any protocol will match.

Raises an auditing event socket.getservbyport with arguments port, protocolname.

socket.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.

socket.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.

Changed in version 3.10:版本3.10中更改： Raises OverflowError if x does not fit in a 16-bit unsigned integer.

socket.htonl(x)

Convert 32-bit positive integers from host to network byte order. 将32位正整数从主机转换为网络字节顺序。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.在主机字节顺序与网络字节顺序相同的机器上，这是一个无操作；否则，它将执行4字节交换操作。

socket.htons(x)

Convert 16-bit positive integers from host to network byte order. 将16位正整数从主机转换为网络字节顺序。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.在主机字节顺序与网络字节顺序相同的机器上，这是一个无操作；否则，它将执行2字节交换操作。

Changed in version 3.10:版本3.10中更改： Raises OverflowError if x does not fit in a 16-bit unsigned integer.如果x不适合16位无符号整数，则引发OverflowError。

socket.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 bytes object four characters in length.将IPv4地址从虚线四字符串格式（例如“123.45.67.89”）转换为32位压缩二进制格式，作为长度为四个字符的字节对象。 This is useful when conversing with a program that uses the standard C library and needs objects of type struct in_addr, which is the C type for the 32-bit packed binary this function returns.这在与使用标准C库且需要struct in_addr类型对象的程序进行转换时非常有用，struct in_addr是此函数返回的32位压缩二进制文件的C类型。

inet_aton() also accepts strings with less than three dots; see the Unix manual page inet(3) for details.

If the IPv4 address string passed to this function is invalid, OSError will be raised. Note that exactly what is valid depends on the underlying C implementation of inet_aton().

inet_aton() does not support IPv6, and inet_pton() should be used instead for IPv4/v6 dual stack support.

socket.inet_ntoa(packed_ip)

Convert a 32-bit packed IPv4 address (a bytes-like object four bytes 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 struct in_addr, which is the C type for the 32-bit packed binary data this function takes as an argument.

If the byte sequence passed to this function is not exactly 4 bytes in length, OSError will be raised. inet_ntoa() does not support IPv6, and inet_ntop() should be used instead for IPv4/v6 dual stack support.

Changed in version 3.5:版本3.5中更改： Writable bytes-like object is now accepted.

socket.inet_pton(address_family, ip_string)

Convert an IP address from its family-specific string format to a packed, binary format. 将IP地址从其系列特定的字符串格式转换为压缩的二进制格式。inet_pton() is useful when a library or network protocol calls for an object of type struct in_addr (similar to inet_aton()) or struct in6_addr.

Supported values for address_family are currently AF_INET and AF_INET6. If the IP address string ip_string is invalid, OSError will be raised. Note that exactly what is valid depends on both the value of address_family and the underlying implementation of inet_pton().

Availability: Unix (maybe not all platforms), Windows.

Changed in version 3.4:版本3.4中更改： Windows support added

socket.inet_ntop(address_family, packed_ip)

Convert a packed IP address (a bytes-like object of some number of bytes) to its standard, family-specific string representation (for example, '7.10.0.5' or '5aef:2b::8'). inet_ntop() is useful when a library or network protocol returns an object of type struct in_addr (similar to inet_ntoa()) or struct in6_addr.

Supported values for address_family are currently AF_INET and AF_INET6. If the bytes object packed_ip is not the correct length for the specified address family, ValueError will be raised. OSError is raised for errors from the call to inet_ntop().

Availability: Unix (maybe not all platforms), Windows.

Changed in version 3.4:版本3.4中更改： Windows support added

Changed in version 3.5:版本3.5中更改： Writable bytes-like object is now accepted.

socket.CMSG_LEN(length)

Return the total length, without trailing padding, of an ancillary data item with associated data of the given length. This value can often be used as the buffer size for recvmsg() to receive a single item of ancillary data, but RFC 3542 requires portable applications to use CMSG_SPACE() and thus include space for padding, even when the item will be the last in the buffer. Raises OverflowError if length is outside the permissible range of values.

Availability: most Unix platforms, possibly others.

New in version 3.3.版本3.3中新增。

socket.CMSG_SPACE(length)

Return the buffer size needed for recvmsg() to receive an ancillary data item with associated data of the given length, along with any trailing padding. The buffer space needed to receive multiple items is the sum of the CMSG_SPACE() values for their associated data lengths. Raises OverflowError if length is outside the permissible range of values.

Note that some systems might support ancillary data without providing this function. Also note that setting the buffer size using the results of this function may not precisely limit the amount of ancillary data that can be received, since additional data may be able to fit into the padding area.

Availability: most Unix platforms, possibly others.：大多数Unix平台，可能还有其他平台。

New in version 3.3.版本3.3中新增。

socket.getdefaulttimeout()

Return the default timeout in seconds (float) 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.

socket.setdefaulttimeout(timeout)

Set the default timeout in seconds (float) for new socket objects. When the socket module is first imported, the default is None. See settimeout() for possible values and their respective meanings.

socket.sethostname(name)

Set the machine’s hostname to name. This will raise an OSError if you don’t have enough rights.

Raises an auditing event socket.sethostname with argument name.

Availability: Unix.

New in version 3.3.版本3.3中新增。

socket.if_nameindex()

Return a list of network interface information (index int, name string) tuples. OSError if the system call fails.

Availability: Unix, Windows.

New in version 3.3.版本3.3中新增。

Changed in version 3.8:版本3.8中更改： Windows support was added.

Note

On Windows network interfaces have different names in different contexts (all names are examples):

  • UUID: {FB605B73-AAC2-49A6-9A2F-25416AEA0573}

  • name: ethernet_32770

  • friendly name: vEthernet (nat)

  • description: Hyper-V Virtual Ethernet Adapter

This function returns names of the second form from the list, ethernet_32770 in this example case.此函数返回列表中第二个表单的名称，在本例中为ethernet_32770。

socket.if_nametoindex(if_name)

Return a network interface index number corresponding to an interface name. OSError if no interface with the given name exists.

Availability: Unix, Windows.

New in version 3.3.版本3.3中新增。

Changed in version 3.8:版本3.8中更改： Windows support was added.

See also

“Interface name” is a name as documented in if_nameindex().

socket.if_indextoname(if_index)

Return a network interface name corresponding to an interface index number. OSError if no interface with the given index exists.

Availability: Unix, Windows.

New in version 3.3.版本3.3中新增。

Changed in version 3.8:版本3.8中更改： Windows support was added.

See also

“Interface name” is a name as documented in if_nameindex().

socket.send_fds(sock, buffers, fds[, flags[, address]])

Send the list of file descriptors fds over an AF_UNIX socket sock. The fds parameter is a sequence of file descriptors. Consult sendmsg() for the documentation of these parameters.

Availability: Unix supporting sendmsg() and SCM_RIGHTS mechanism.

New in version 3.9.版本3.9中新增。

socket.recv_fds(sock, bufsize, maxfds[, flags])

Receive up to maxfds file descriptors from an AF_UNIX socket sock. Return (msg, list(fds), flags, addr). Consult recvmsg() for the documentation of these parameters.

Availability: Unix supporting recvmsg() and SCM_RIGHTS mechanism.

New in version 3.9.版本3.9中新增。

Note

Any truncated integers at the end of the list of file descriptors.文件描述符列表末尾的任何截断整数。

Socket Objects对象

Socket objects have the following methods. Socket对象有以下方法。Except for makefile(), these correspond to Unix system calls applicable to sockets.

Changed in version 3.2:版本3.2中更改： Support for the context manager protocol was added. Exiting the context manager is equivalent to calling close().

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.

The newly created socket is non-inheritable.

Changed in version 3.4:版本3.4中更改： The socket is now non-inheritable.

Changed in version 3.5:版本3.5中更改： If the system call is interrupted and the signal handler does not raise an exception, the method now retries the system call instead of raising an InterruptedError exception (see PEP 475 for the rationale).

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.)

Raises an auditing event socket.bind with arguments self, address.

socket.close()

Mark the socket closed. The underlying system resource (e.g. a file descriptor) is also closed when all file objects from makefile() are closed. Once that happens, 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, but it is recommended to close() them explicitly, or to use a with statement around them.

Changed in version 3.6:版本3.6中更改： OSError is now raised if an error occurs when the underlying close() call is made.

Note

close() releases the resource associated with a connection but does not necessarily close the connection immediately. If you want to close the connection in a timely fashion, call shutdown() before close().

socket.connect(address)

Connect to a remote socket at address. (The format of address depends on the address family — see above.)

If the connection is interrupted by a signal, the method waits until the connection completes, or raise a TimeoutError on timeout, if the signal handler doesn’t raise an exception and the socket is blocking or has a timeout. For non-blocking sockets, the method raises an InterruptedError exception if the connection is interrupted by a signal (or the exception raised by the signal handler).

Raises an auditing event socket.connect with arguments self, address.

Changed in version 3.5:版本3.5中更改： The method now waits until the connection completes instead of raising an InterruptedError exception if the connection is interrupted by a signal, the signal handler doesn’t raise an exception and the socket is blocking or has a timeout (see the PEP 475 for the rationale).

socket.connect_ex(address)

Like connect(address), but return an error indicator instead of raising an exception for errors returned by the C-level 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 errno variable. This is useful to support, for example, asynchronous connects.

Raises an auditing event socket.connect with arguments self, address.

socket.detach()

Put the socket object into closed state without actually closing the underlying file descriptor. 将套接字对象置于关闭状态，而不实际关闭底层文件描述符。The file descriptor is returned, and can be reused for other purposes.返回文件描述符，并可用于其他目的。

New in version 3.2.版本3.2中新增。

socket.dup()

Duplicate the socket.

The newly created socket is non-inheritable.

Changed in version 3.4:版本3.4中更改： The socket is now non-inheritable.

socket.fileno()

Return the socket’s file descriptor (a small integer), or -1 on failure. This is useful with select.select().

Under Windows the small integer returned by this method cannot be used where a file descriptor can be used (such as os.fdopen()). Unix does not have this limitation.

socket.get_inheritable()

Get the inheritable flag of the socket’s file descriptor or socket’s handle: True if the socket can be inherited in child processes, False if it cannot.

New in version 3.4.版本3.4中新增。

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.

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.)

socket.getsockopt(level, optname[, buflen])

Return the value of the given socket option (see the Unix man page getsockopt(2)). The needed symbolic constants (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 bytes object. It is up to the caller to decode the contents of the buffer (see the optional built-in module struct for a way to decode C structures encoded as byte strings).

socket.getblocking()

Return True if socket is in blocking mode, False if in non-blocking.

This is equivalent to checking socket.gettimeout() == 0.

New in version 3.7.版本3.7中新增。

socket.gettimeout()

Return the timeout in seconds (float) associated with socket operations, or None if no timeout is set. This reflects the last call to setblocking() or settimeout().

socket.ioctl(control, option)
Platform

Windows

The ioctl() method is a limited interface to the WSAIoctl system interface. Please refer to the Win32 documentation for more information.

On other platforms, the generic fcntl.fcntl() and fcntl.ioctl() functions may be used; they accept a socket object as their first argument.

Currently only the following control codes are supported: SIO_RCVALL, SIO_KEEPALIVE_VALS, and SIO_LOOPBACK_FAST_PATH.

Changed in version 3.6:版本3.6中更改： SIO_LOOPBACK_FAST_PATH was added.

socket.listen([backlog])

Enable a server to accept connections. If backlog is specified, it must be at least 0 (if it is lower, it is set to 0); it specifies the number of unaccepted connections that the system will allow before refusing new connections. If not specified, a default reasonable value is chosen.

Changed in version 3.5:版本3.5中更改： The backlog parameter is now optional.

socket.makefile(mode='r', buffering=None, *, encoding=None, errors=None, newline=None)

Return a file object associated with the socket. The exact returned type depends on the arguments given to makefile(). These arguments are interpreted the same way as by the built-in open() function, except the only supported mode values are 'r' (default), 'w' and 'b'.

The socket must be in blocking mode; it can have a timeout, but the file object’s internal buffer may end up in an inconsistent state if a timeout occurs.

Closing the file object returned by makefile() won’t close the original socket unless all other file objects have been closed and socket.close() has been called on the socket object.

Note

On Windows, the file-like object created by makefile() cannot be used where a file object with a file descriptor is expected, such as the stream arguments of subprocess.Popen().

socket.recv(bufsize[, flags])

Receive data from the socket. The return value is a bytes object representing the data received. The maximum amount of data to be received at once is specified by bufsize. See the Unix manual page 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.为了与硬件和网络现实最佳匹配，bufsize的值应该是相对较小的2次方，例如4096。

Changed in version 3.5:版本3.5中更改： If the system call is interrupted and the signal handler does not raise an exception, the method now retries the system call instead of raising an InterruptedError exception (see PEP 475 for the rationale).

socket.recvfrom(bufsize[, flags])

Receive data from the socket. The return value is a pair (bytes, address) where bytes is a bytes object representing the data received and address is the address of the socket sending the data. See the Unix manual page 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.)

Changed in version 3.5:版本3.5中更改： If the system call is interrupted and the signal handler does not raise an exception, the method now retries the system call instead of raising an InterruptedError exception (see PEP 475 for the rationale).

Changed in version 3.7:版本3.7中更改： For multicast IPv6 address, first item of address does not contain %scope_id part anymore. In order to get full IPv6 address use getnameinfo().

socket.recvmsg(bufsize[, ancbufsize[, flags]])

Receive normal data (up to bufsize bytes) and ancillary data from the socket. The ancbufsize argument sets the size in bytes of the internal buffer used to receive the ancillary data; it defaults to 0, meaning that no ancillary data will be received. Appropriate buffer sizes for ancillary data can be calculated using CMSG_SPACE() or CMSG_LEN(), and items which do not fit into the buffer might be truncated or discarded. The flags argument defaults to 0 and has the same meaning as for recv().

The return value is a 4-tuple: (data, ancdata, msg_flags, address). The data item is a bytes object holding the non-ancillary data received. The ancdata item is a list of zero or more tuples (cmsg_level, cmsg_type, cmsg_data) representing the ancillary data (control messages) received: cmsg_level and cmsg_type are integers specifying the protocol level and protocol-specific type respectively, and cmsg_data is a bytes object holding the associated data. The msg_flags item is the bitwise OR of various flags indicating conditions on the received message; see your system documentation for details. If the receiving socket is unconnected, address is the address of the sending socket, if available; otherwise, its value is unspecified.

On some systems, sendmsg() and recvmsg() can be used to pass file descriptors between processes over an AF_UNIX socket. When this facility is used (it is often restricted to SOCK_STREAM sockets), recvmsg() will return, in its ancillary data, items of the form (socket.SOL_SOCKET, socket.SCM_RIGHTS, fds), where fds is a bytes object representing the new file descriptors as a binary array of the native C int type. If recvmsg() raises an exception after the system call returns, it will first attempt to close any file descriptors received via this mechanism.

Some systems do not indicate the truncated length of ancillary data items which have been only partially received. If an item appears to extend beyond the end of the buffer, recvmsg() will issue a RuntimeWarning, and will return the part of it which is inside the buffer provided it has not been truncated before the start of its associated data.

On systems which support the SCM_RIGHTS mechanism, the following function will receive up to maxfds file descriptors, returning the message data and a list containing the descriptors (while ignoring unexpected conditions such as unrelated control messages being received). See also sendmsg().

import socket, array
def recv_fds(sock, msglen, maxfds):
    fds = array.array("i")   # Array of ints
    msg, ancdata, flags, addr = sock.recvmsg(msglen, socket.CMSG_LEN(maxfds * fds.itemsize))
    for cmsg_level, cmsg_type, cmsg_data in ancdata:
        if cmsg_level == socket.SOL_SOCKET and cmsg_type == socket.SCM_RIGHTS:
            # Append data, ignoring any truncated integers at the end.
            fds.frombytes(cmsg_data[:len(cmsg_data) - (len(cmsg_data) % fds.itemsize)])
    return msg, list(fds)

Availability: most Unix platforms, possibly others.

New in version 3.3.版本3.3中新增。

Changed in version 3.5:版本3.5中更改： If the system call is interrupted and the signal handler does not raise an exception, the method now retries the system call instead of raising an InterruptedError exception (see PEP 475 for the rationale).

socket.recvmsg_into(buffers[, ancbufsize[, flags]])

Receive normal data and ancillary data from the socket, behaving as recvmsg() would, but scatter the non-ancillary data into a series of buffers instead of returning a new bytes object. The buffers argument must be an iterable of objects that export writable buffers (e.g. bytearray objects); these will be filled with successive chunks of the non-ancillary data until it has all been written or there are no more buffers. The operating system may set a limit (sysconf() value SC_IOV_MAX) on the number of buffers that can be used. The ancbufsize and flags arguments have the same meaning as for recvmsg().

The return value is a 4-tuple: (nbytes, ancdata, msg_flags, address), where nbytes is the total number of bytes of non-ancillary data written into the buffers, and ancdata, msg_flags and address are the same as for recvmsg().

Example:

>>> import socket
>>> s1, s2 = socket.socketpair()
>>> b1 = bytearray(b'----')
>>> b2 = bytearray(b'0123456789')
>>> b3 = bytearray(b'--------------')
>>> s1.send(b'Mary had a little lamb')
22
>>> s2.recvmsg_into([b1, memoryview(b2)[2:9], b3])
(22, [], 0, None)
>>> [b1, b2, b3]
[bytearray(b'Mary'), bytearray(b'01 had a 9'), bytearray(b'little lamb---')]

Availability: most Unix platforms, possibly others.

New in version 3.3.版本3.3中新增。

socket.recvfrom_into(buffer[, nbytes[, flags]])

Receive data from the socket, writing it into buffer instead of creating a new bytestring. 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 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.)

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 bytestring. If nbytes is not specified (or 0), receive up to the size available in the given buffer. Returns the number of bytes received. See the Unix manual page recv(2) for the meaning of the optional argument flags; it defaults to zero.

socket.send(bytes[, 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 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. For further information on this topic, consult the Socket Programming HOWTO.

Changed in version 3.5:版本3.5中更改： If the system call is interrupted and the signal handler does not raise an exception, the method now retries the system call instead of raising an InterruptedError exception (see PEP 475 for the rationale).

socket.sendall(bytes[, 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 recv() above. Unlike send(), this method continues to send data from bytes 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.

Changed in version 3.5:版本3.5中更改： The socket timeout is no more reset each time data is sent successfully. The socket timeout is now the maximum total duration to send all data.

Changed in version 3.5:版本3.5中更改： If the system call is interrupted and the signal handler does not raise an exception, the method now retries the system call instead of raising an InterruptedError exception (see PEP 475 for the rationale).

socket.sendto(bytes, address)
socket.sendto(bytes, 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 recv() above. Return the number of bytes sent. (The format of address depends on the address family — see above.)

Raises an auditing event socket.sendto with arguments self, address.

Changed in version 3.5:版本3.5中更改： If the system call is interrupted and the signal handler does not raise an exception, the method now retries the system call instead of raising an InterruptedError exception (see PEP 475 for the rationale).

socket.sendmsg(buffers[, ancdata[, flags[, address]]])

Send normal and ancillary data to the socket, gathering the non-ancillary data from a series of buffers and concatenating it into a single message. The buffers argument specifies the non-ancillary data as an iterable of bytes-like objects (e.g. bytes objects); the operating system may set a limit (sysconf() value SC_IOV_MAX) on the number of buffers that can be used. The ancdata argument specifies the ancillary data (control messages) as an iterable of zero or more tuples (cmsg_level, cmsg_type, cmsg_data), where cmsg_level and cmsg_type are integers specifying the protocol level and protocol-specific type respectively, and cmsg_data is a bytes-like object holding the associated data. Note that some systems (in particular, systems without CMSG_SPACE()) might support sending only one control message per call. The flags argument defaults to 0 and has the same meaning as for send(). If address is supplied and not None, it sets a destination address for the message. The return value is the number of bytes of non-ancillary data sent.

The following function sends the list of file descriptors fds over an AF_UNIX socket, on systems which support the SCM_RIGHTS mechanism. See also recvmsg().

import socket, array
def send_fds(sock, msg, fds):
    return sock.sendmsg([msg], [(socket.SOL_SOCKET, socket.SCM_RIGHTS, array.array("i", fds))])

Availability: most Unix platforms, possibly others.

Raises an auditing event socket.sendmsg with arguments self, address.

New in version 3.3.版本3.3中新增。

Changed in version 3.5:版本3.5中更改： If the system call is interrupted and the signal handler does not raise an exception, the method now retries the system call instead of raising an InterruptedError exception (see PEP 475 for the rationale).

socket.sendmsg_afalg([msg, ]*, op[, iv[, assoclen[, flags]]])

Specialized version of sendmsg() for AF_ALG socket. Set mode, IV, AEAD associated data length and flags for AF_ALG socket.

Availability: Linux >= 2.6.38.

New in version 3.6.版本3.6中新增。

socket.sendfile(file, offset=0, count=None)

Send a file until EOF is reached by using high-performance os.sendfile and return the total number of bytes which were sent. file must be a regular file object opened in binary mode. If os.sendfile is not available (e.g. Windows) or file is not a regular file send() will be used instead. offset tells from where to start reading the file. If specified, count is the total number of bytes to transmit as opposed to sending the file until EOF is reached. File position is updated on return or also in case of error in which case file.tell() can be used to figure out the number of bytes which were sent. The socket must be of SOCK_STREAM type. Non-blocking sockets are not supported.

New in version 3.5.版本3.5中新增。

socket.set_inheritable(inheritable)

Set the inheritable flag of the socket’s file descriptor or socket’s handle.

New in version 3.4.版本3.4中新增。

socket.setblocking(flag)

Set blocking or non-blocking mode of the socket: if flag is false, the socket is set to non-blocking, else to blocking mode.

This method is a shorthand for certain settimeout() calls:

  • sock.setblocking(True) is equivalent to sock.settimeout(None)

  • sock.setblocking(False) is equivalent to sock.settimeout(0.0)

Changed in version 3.7:版本3.7中更改： The method no longer applies SOCK_NONBLOCK flag on socket.type.

socket.settimeout(value)

Set a timeout on blocking socket operations. 设置阻塞套接字操作的超时。The value argument can be a nonnegative floating point number expressing seconds, or None. 值参数可以是表示秒的非负浮点数，也可以是None。If a non-zero value is given, subsequent socket operations will raise a timeout exception if the timeout period value has elapsed before the operation has completed. If zero is given, the socket is put in non-blocking mode. If None is given, the socket is put in blocking mode.

For further information, please consult the notes on socket timeouts.

Changed in version 3.7:版本3.7中更改： The method no longer toggles SOCK_NONBLOCK flag on socket.type.

socket.setsockopt(level, optname, value: int)
socket.setsockopt(level, optname, value: buffer)
socket.setsockopt(level, optname, None, optlen: int)

Set the value of the given socket option (see the Unix manual page setsockopt(2)). The needed symbolic constants are defined in the socket module (SO_* etc.). The value can be an integer, None or a bytes-like object representing a buffer. In the later case it is up to the caller to ensure that the bytestring contains the proper bits (see the optional built-in module struct for a way to encode C structures as bytestrings). When value is set to None, optlen argument is required. It’s equivalent to call setsockopt() C function with optval=NULL and optlen=optlen.

Changed in version 3.5:版本3.5中更改： Writable bytes-like object is now accepted.

Changed in version 3.6:版本3.6中更改： setsockopt(level, optname, None, optlen: int) form added.

socket.shutdown(how)

Shut down one or both halves of the connection. If how is SHUT_RD, further receives are disallowed. If how is SHUT_WR, further sends are disallowed. If how is SHUT_RDWR, further sends and receives are disallowed.

socket.share(process_id)

Duplicate a socket and prepare it for sharing with a target process. The target process must be provided with process_id. The resulting bytes object can then be passed to the target process using some form of interprocess communication and the socket can be recreated there using fromshare(). Once this method has been called, it is safe to close the socket since the operating system has already duplicated it for the target process.

Availability: Windows.

New in version 3.3.版本3.3中新增。

Note that there are no methods read() or write(); use recv() and send() without flags argument instead.

Socket objects also have these (read-only) attributes that correspond to the values given to the socket constructor.套接字对象还具有这些（只读）属性，这些属性与socket构造函数的值相对应。

socket.family

The socket family.

socket.type

The socket type.

socket.proto

The socket protocol.

Notes on socket timeouts关于套接字超时的说明

A socket object can be in one of three modes: blocking, non-blocking, or timeout. 套接字对象可以处于三种模式之一：阻塞、非阻塞或超时。Sockets are by default always created in blocking mode, but this can be changed by calling setdefaulttimeout().默认情况下，套接字总是以阻塞模式创建的，但可以通过调用setdefaulttimeout()来更改。

  • In blocking mode, operations block until complete or the system returns an error (such as connection timed out).

  • In non-blocking mode, operations fail (with an error that is unfortunately system-dependent) if they cannot be completed immediately: functions from the select can be used to know when and whether a socket is available for reading or writing.

  • In timeout mode, operations fail if they cannot be completed within the timeout specified for the socket (they raise a timeout exception) or if the system returns an error.

Note

At the operating system level, sockets in timeout mode are internally set in non-blocking mode. Also, the blocking and timeout modes are shared between file descriptors and socket objects that refer to the same network endpoint. This implementation detail can have visible consequences if e.g. you decide to use the fileno() of a socket.

Timeouts and the connect method超时和connect方法

The connect() operation is also subject to the timeout setting, and in general it is recommended to call settimeout() before calling connect() or pass a timeout parameter to create_connection(). However, the system network stack may also return a connection timeout error of its own regardless of any Python socket timeout setting.

Timeouts and the accept method超时和accept方法

If getdefaulttimeout() is not None, sockets returned by the accept() method inherit that timeout. Otherwise, the behaviour depends on settings of the listening socket:

  • if the listening socket is in blocking mode or in timeout mode, the socket returned by accept() is in blocking mode;

  • if the listening socket is in non-blocking mode, whether the socket returned by accept() is in blocking or non-blocking mode is operating system-dependent. If you want to ensure cross-platform behaviour, it is recommended you manually override this setting.

Example示例

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 socket(), bind(), listen(), accept() (possibly repeating the accept() to service more than one client), while a client only needs the sequence socket(), connect(). Also note that the server does not sendall()/recv() on the socket it is listening on but on the new socket returned by accept().

The first two examples support IPv4 only.前两个示例仅支持IPv4。

# Echo server program
import socket
HOST = ''                 # Symbolic name meaning all available interfaces
PORT = 50007              # Arbitrary non-privileged port
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
    s.bind((HOST, PORT))
    s.listen(1)
    conn, addr = s.accept()
    with conn:
        print('Connected by', addr)
        while True:
            data = conn.recv(1024)
            if not data: break
            conn.sendall(data)
# Echo client program
import socket
HOST = 'daring.cwi.nl'    # The remote host
PORT = 50007              # The same port as used by the server
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
    s.connect((HOST, PORT))
    s.sendall(b'Hello, world')
    data = s.recv(1024)
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 OSError as msg:
        s = None
        continue
    try:
        s.bind(sa)
        s.listen(1)
    except OSError as msg:
        s.close()
        s = None
        continue
    break
if s is None:
    print('could not open socket')
    sys.exit(1)
conn, addr = s.accept()
with conn:
    print('Connected by', addr)
    while True:
        data = conn.recv(1024)
        if not data: break
        conn.send(data)
# 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 OSError as msg:
        s = None
        continue
    try:
        s.connect(sa)
    except OSError as msg:
        s.close()
        s = None
        continue
    break
if s is None:
    print('could not open socket')
    sys.exit(1)
with s:
    s.sendall(b'Hello, world')
    data = s.recv(1024)
print('Received', repr(data))

The next 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)

The next example shows how to use the socket interface to communicate to a CAN network using the raw socket protocol. To use CAN with the broadcast manager protocol instead, open a socket with:

socket.socket(socket.AF_CAN, socket.SOCK_DGRAM, socket.CAN_BCM)

After binding (CAN_RAW) or connecting (CAN_BCM) the socket, you can use the socket.send(), and the socket.recv() operations (and their counterparts) on the socket object as usual.

This last example might require special privileges:

import socket
import struct
# CAN frame packing/unpacking (see 'struct can_frame' in <linux/can.h>)

can_frame_fmt = "=IB3x8s"
can_frame_size = struct.calcsize(can_frame_fmt)

def build_can_frame(can_id, data):
    can_dlc = len(data)
    data = data.ljust(8, b'\x00')
    return struct.pack(can_frame_fmt, can_id, can_dlc, data)

def dissect_can_frame(frame):
    can_id, can_dlc, data = struct.unpack(can_frame_fmt, frame)
    return (can_id, can_dlc, data[:can_dlc])


# create a raw socket and bind it to the 'vcan0' interface
s = socket.socket(socket.AF_CAN, socket.SOCK_RAW, socket.CAN_RAW)
s.bind(('vcan0',))

while True:
    cf, addr = s.recvfrom(can_frame_size)

    print('Received: can_id=%x, can_dlc=%x, data=%s' % dissect_can_frame(cf))

    try:
        s.send(cf)
    except OSError:
        print('Error sending CAN frame')

    try:
        s.send(build_can_frame(0x01, b'\x01\x02\x03'))
    except OSError:
        print('Error sending CAN frame')

Running an example several times with too small delay between executions, could lead to this error:

OSError: [Errno 98] Address already in use

This is because the previous execution has left the socket in a TIME_WAIT state, and can’t be immediately reused.

There is a socket flag to set, in order to prevent this, socket.SO_REUSEADDR:

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((HOST, PORT))

the SO_REUSEADDR flag tells the kernel to reuse a local socket in TIME_WAIT state, without waiting for its natural timeout to expire.

See also

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

  • An Introductory 4.3BSD Interprocess Communication Tutorial, by Stuart Sechrest

  • 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.