17.2. socket — 低级网络接口 ¶

此模块提供访问 BSD socket interface. It is available on all modern Unix systems, Windows, Mac OS X, BeOS, OS/2, and probably additional platforms.

注意

某些行为可能从属平台，由于调用的是操作系统的套接字 API。

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.

Python 接口是 Unix 系统调用和套接字库接口到 Python 面向对象风格的简明直译： socket() 函数返回 套接字对象 其方法有实现各种套接字系统调用。参数类型比 C 接口中的要高级一些：如同采用 read() and write() 操作 Python 文件，接收操作的缓冲分配是自动的，而发送操作的缓冲长度是隐式的。

Socket addresses are represented as follows: A single string is used for the AF_UNIX address family. A pair (host, port) 用于 AF_INET 地址族，其中 host 是以 Internet 域表示法表示主机名的字符串像 'daring.cwi.nl' 或 IPv4 地址像 '100.50.200.5' ，和 port is an integer. For AF_INET6 地址族 4 元组 (host, port, flowinfo, scopeid) 的使用，其中 flowinfo and scopeid 表示 sin6_flowinfo and sin6_scope_id member in struct sockaddr_in6 在 C 中。对于 socket 模块方法， flowinfo and scopeid 可以省略只为向后兼容。注意，不管怎样，省略 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 INADDR_ANY , and the string '<broadcast>' 表示 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.

若使用主机名在 host 部分为 IPv4/v6 套接字地址，程序可能展示不确定行为，因为 Python 使用解析自 DNS 的第一返回地址。套接字地址将以不同方式被解析成实际 IPv4/v6 地址，取决于解析自 DNS 的结果和/或主机配置。对于确定性行为，使用数值地址在 host 部分。

New in version 2.5: AF_NETLINK sockets are represented as pairs pid, groups .

2.6 版新增： Linux-only support for TIPC is also available using the AF_TIPC 地址族。TIPC 是开放的、基于非 IP 的网络协议，设计用于集群计算机环境。地址由元组表示，且字段从属地址类型。一般元组形式为 (addr_type, v1, v2, v3 [, scope]) ，其中：

• addr_type 是某一 TIPC_ADDR_NAMESEQ , TIPC_ADDR_NAME ，或 TIPC_ADDR_ID .

• scope 是某一 TIPC_ZONE_SCOPE , TIPC_CLUSTER_SCOPE ，和 TIPC_NODE_SCOPE .

• 若 addr_type is TIPC_ADDR_NAME ，那么 v1 是服务器类型， v2 是端口标识符，和 v3 应该为 0。

  若 addr_type is TIPC_ADDR_NAMESEQ ，那么 v1 是服务器类型， v2 是更低端口号，和 v3 是更高端口号。

  若 addr_type is TIPC_ADDR_ID ，那么 v1 是节点， v2 是引用，和 v3 应被设为 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 socket.error .

支持非阻塞模式透过 setblocking() 。支持基于超时的一般化透过 settimeout() .

模块 socket exports the following constants and functions:

exception socket. error ¶

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 os.error . See the module errno , which contains names for the error codes defined by the underlying operating system.

2.6 版改变： socket.error is now a child class of IOError .

exception socket. herror ¶

This exception is raised for address-related errors, i.e. for functions that use h_errno in the C API, including gethostbyname_ex() and gethostbyaddr() .

The accompanying value is a pair (h_errno, string) 表示由库调用返回的错误。 string 表示描述对于 h_errno ，如返回通过 hstrerror() C 函数。

exception socket. gaierror ¶

This exception is raised for address-related errors, for getaddrinfo() and getnameinfo() 。伴随值是一对 (error, string) 表示由库调用返回的错误。 string 表示描述对于 error ，如返回通过 gai_strerror() C function. The error 值将匹配某一 EAI_* 常量 (在此模块中有定义)。

exception socket. timeout ¶

This exception is raised when a timeout occurs on a socket which has had timeouts enabled via a prior call to settimeout() . The accompanying value is a string whose value is currently always “timed out”.

2.3 版新增。

socket. AF_UNIX ¶

socket. AF_INET ¶

socket. AF_INET6 ¶

这些常量表示地址 (和协议) 系列，用作第一自变量对于 socket() 。若 AF_UNIX constant is not defined then this protocol is unsupported.

socket. SOCK_STREAM ¶

socket. SOCK_DGRAM ¶

socket. SOCK_RAW ¶

socket. SOCK_RDM ¶

socket. SOCK_SEQPACKET ¶

这些常量表示套接字类型，用作第 2 自变量对于 socket() . (Only SOCK_STREAM and SOCK_DGRAM 似乎很有用，一般来说)。

SO_*

socket. SOMAXCONN ¶

MSG_*

SOL_*

IPPROTO_*

IPPORT_*

INADDR_*

IP_*

IPV6_*

EAI_*

AI_*

NI_*

TCP_*

这些形式的很多常量，在有关套接字和/或 IP 协议的 Unix 文档编制中有文档化，在 socket 模块也有定义。它们一般是自变量用于 setsockopt() and getsockopt() 方法的套接字对象。在大多数情况下，在 Unix 头文件中有定义的那些符号才会被定义；对于少数符号，提供默认值。

SIO_*

RCVALL_*

用于 Windows WSAIoctl() 的常量。常量被用作为自变量对于 ioctl() 方法为套接字对象。

2.6 版新增。

TIPC_*

TIPC related constants, matching the ones exported by the C socket API. See the TIPC documentation for more information.

2.6 版新增。

socket. has_ipv6 ¶

此常量包含指示平台是否支持 IPv6 的布尔值。

2.3 版新增。

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

Connect to a TCP service listening on the Internet address (2 元素元组 (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.

传递可选 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 getdefaulttimeout() 被使用。

若供给， source_address 必须是 2 元素元组 (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.

2.6 版新增。

2.7 版改变： source_address 被添加。

socket. getaddrinfo ( host , port [ , 系列 [ , socktype [ , proto [ , flags ] ] ] ] ) ¶

翻译 host / port 自变量成 5 元组序列，包含创建连接到该服务的套接字的所有必要自变量。 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 系列 , socktype and proto arguments can be optionally specified in order to narrow the list of addresses returned. By default, their value is 0 , meaning that the full range of results is selected. The flags argument can be one or several of the AI_* constants, and will influence how results are computed and returned. Its default value is 0 。例如， AI_NUMERICHOST will disable domain name resolution and will raise an error if host is a domain name.

函数返回的 5 元组列表具有以下结构：

(family, socktype, proto, canonname, sockaddr)

在这些元组中， 系列 , socktype , proto are all integers and are meant to be passed to the socket() 函数。 canonname will be a string representing the canonical name of the host if AI_CANONNAME 属于 flags argument; else canonname will be empty. sockaddr is a tuple describing a socket address, whose format depends on the returned 系列 ( (address, port) 2-tuple for AF_INET ， (address, port, flow info, scope id) 4-tuple for AF_INET6 ), and is meant to be passed to the socket.connect() 方法。

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, 0, 0, socket.IPPROTO_TCP)
[(10, 1, 6, '', ('2606:2800:220:1:248:1893:25c8:1946', 80, 0, 0)),
 (2, 1, 6, '', ('93.184.216.34', 80))]
						

2.2 版新增。

socket. getfqdn ( [ 名称 ] ) ¶

返回完全合格的域名对于 name 。若 name 被省略或空，解释成本地主机。要找到完全合格的名称，主机名的返回通过 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 gethostname() 被返回。

2.0 版新增。

socket. gethostbyname ( hostname ) ¶

将主机名翻译成 IPv4 地址格式。IPv4 地址被返回成字符串，譬如 '100.50.200.5' 。若主机名本身是 IPv4 地址，它将不变返回。见 gethostbyname_ex() 了解更完整接口。 gethostbyname() 不支持 IPv6 名称解析，和 getaddrinfo() 应该被使用而不是 IPv4/v6 双堆栈支持。

socket. gethostbyname_ex ( hostname ) ¶

将主机名翻译成 IPv4 地址格式，扩展接口。返回 3 元组 (hostname, aliaslist, ipaddrlist) where hostname 是首要主机名响应给定 ip_address , aliaslist 是同一地址的备选主机名列表 (可能为空)，和 ipaddrlist 是同一主机同一接口的 IPv4 地址列表 (经常但始终不是单个地址)。 gethostbyname_ex() 不支持 IPv6 名称解析，和 getaddrinfo() 应该被使用而不是 IPv4/v6 双堆栈支持。

socket. gethostname ( ) ¶

返回包含 Python 解释器目前正在其中执行的机器主机名字符串。

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.

注意： gethostname() 不会始终返回完全合格的域名；使用 getfqdn() (see above).

socket. gethostbyaddr ( ip_address ) ¶

返回 3 元组 (hostname, aliaslist, ipaddrlist) where hostname 是首要主机名响应给定 ip_address , aliaslist 是同一地址的备选主机名列表 (可能为空)，和 ipaddrlist 是同一主机同一接口的 IPv4/v6 地址列表 (很可能只包含单个地址)。要找到完全合格的域名，使用函数 getfqdn() . gethostbyaddr() 支持 IPv4 和 IPv6 两者。

socket. getnameinfo ( sockaddr , flags ) ¶

翻译套接字地址 sockaddr 成 2 元素元组 (host, port) 。取决于设置的 flags , the result can contain a fully-qualified domain name or numeric address representation in host 。同样， port 可以包含字符串端口名或数值端口号。

2.2 版新增。

socket. getprotobyname ( protocolname ) ¶

翻译 Internet 协议名称 (例如， '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.

socket. 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.

socket. socket ( [ 系列 [ , type [ , proto ] ] ] ) ¶

使用给定地址族、套接字类型和协议编号，创建新的套接字。地址族应该是 AF_INET (默认)， AF_INET6 or AF_UNIX 。套接字类型应该是 SOCK_STREAM (默认)， SOCK_DGRAM 或者或许某一其它 SOCK_ constants. The protocol number is usually zero and may be omitted in that case.

socket. socketpair ( [ 系列 [ , 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 socket() function above. The default family is AF_UNIX if defined on the platform; otherwise, the default is AF_INET . Availability: Unix.

2.4 版新增。

socket. fromfd ( fd , 系列 , type [ , proto ] ) ¶

Duplicate the file descriptor fd (an integer as returned by a file object’s fileno() method) and build a socket object from the result. Address family, socket type and protocol number are as for the 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.

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.

socket. 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.

socket. 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.

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 string four characters in length. 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.

inet_aton() also accepts strings with less than three dots; see the Unix manual page inet(3) 了解细节。

If the IPv4 address string passed to this function is invalid, socket.error 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() 应该被使用而不是 IPv4/v6 双堆栈支持。

socket. 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 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, socket.error 会被引发。 inet_ntoa() does not support IPv6, and inet_ntop() 应该被使用而不是 IPv4/v6 双堆栈支持。

socket. inet_pton ( address_family , ip_string ) ¶

将 IP 地址从特定系列字符串格式，转换成打包二进制格式。 inet_pton() 很有用当库或网络协议调用对象的类型为 struct in_addr (类似 inet_aton() ) 或 struct in6_addr .

Supported values for address_family are currently AF_INET and AF_INET6 . If the IP address string ip_string is invalid, socket.error 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).

2.3 版新增。

socket. 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' ) inet_ntop() is useful when a library or network protocol returns an object of type struct in_addr (类似 inet_ntoa() ) 或 struct in6_addr .

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

Availability: Unix (maybe not all platforms).

2.3 版新增。

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 .

2.3 版新增。

socket. setdefaulttimeout ( timeout ) ¶

Set 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 .

2.3 版新增。

socket. SocketType ¶

这是表示套接字对象类型的 Python 类型对象。如同 type(socket(...)) .

另请参阅

模块 SocketServer

简化编写网络服务器的类。

模块 ssl

套接字对象的 TLS/SSL 包裹器。

17.2.1. 套接字对象 ¶

套接字对象拥有以下方法。除了 makefile() these correspond to Unix system calls applicable to sockets.

socket. accept ( ) ¶

接受连接。必须将套接字绑定到地址并监听连接。返回值是一对 (conn, address) where conn 是 new 套接字对象用于发送和接收数据当连接上时，和 address 是绑定到连接另一端的套接字地址。

socket. bind ( address ) ¶

将套接字绑定到 address 。套接字必须尚未绑定。(格式对于 address 从属地址族 — 见上文。)

注意

This method has historically accepted a pair of parameters for AF_INET addresses instead of only a tuple. This was never intentional and is no longer available in Python 2.0 and later.

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.

注意

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 ) ¶

连接到远程套接字在 address 。(格式对于 address 从属地址族 — 见上文。)

注意

This method has historically accepted a pair of parameters for AF_INET addresses instead of only a tuple. This was never intentional and is no longer available in Python 2.0 and later.

socket. connect_ex ( address ) ¶

像 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.

注意

This method has historically accepted a pair of parameters for AF_INET addresses instead of only a tuple. This was never intentional and is no longer available in Python 2.0 and later.

socket. fileno ( ) ¶

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

在 Windows，在可以使用文件描述符的地方不可以使用由此方法返回的小整数 (譬如 os.fdopen() )。Unix 没有这种局限性。

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 string. 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 strings).

socket. ioctl ( 控制 , option ) ¶

平台

Windows

The ioctl() method is a limited interface to the WSAIoctl system interface. Please refer to the Win32 文档编制 了解更多信息。

在其它平台，一般 fcntl.fcntl() and fcntl.ioctl() 函数可以使用；它们接受套接字对象作为其第一自变量。

2.6 版新增。

socket. listen ( backlog ) ¶

监听套接字建立的连接。 backlog argument specifies the maximum number of queued connections and should be at least 0; the maximum value is system-dependent (usually 5), the minimum value is forced to 0.

socket. makefile ( [ mode [ , bufsize ] ] ) ¶

返回 文件对象 associated with the socket. (File objects are described in 文件对象 .) The file object does not close the socket explicitly when its close() method is called, but only removes its reference to the socket object, so that the socket will be closed if it is not referenced from anywhere else.

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 file() 函数。

注意

在 Windows，像文件对象的创建通过 makefile() 无法使用若期望具有文件描述符的文件对象，譬如流自变量对于 subprocess.Popen() .

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 。见 Unix 手册页 recv(2) 了解含义对于可选自变量 flags ；默认为 0。

注意

为与硬件和网络实际情况最佳匹配，值对于 bufsize 应该是相对小的 2 的幂，例如 4096。

socket. recvfrom ( bufsize [ , flags ] ) ¶

从套接字接收数据。返回值是成对 (string, address) where string is a string representing the data received and address 是发送数据的套接字地址。见 Unix 手册页 recv(2) 了解含义对于可选自变量 flags ；默认为 0。(格式对于 address 从属地址族 — 见上文。)

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 是发送数据的套接字地址。见 Unix 手册页 recv(2) 了解含义对于可选自变量 flags ；默认为 0。(格式对于 address 从属地址族 — 见上文。)

2.5 版新增。

socket. recv_into ( buffer [ , nbytes [ , flags ] ] ) ¶

接收直到 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. Returns the number of bytes received. See the Unix manual page recv(2) 了解含义对于可选自变量 flags ；默认为 0。

2.5 版新增。

socket. send ( string [ , flags ] ) ¶

发送数据到套接字。套接字必须连接到远程套接字。可选 flags 自变量有相同含义如 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 concept, consult the 套接字编程怎么样 .

socket. sendall ( string [ , flags ] ) ¶

发送数据到套接字。套接字必须连接到远程套接字。可选 flags 自变量有相同含义如 recv() above. Unlike 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.

socket. sendto ( string , address ) ¶

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 。可选 flags 自变量有相同含义如 recv() above. Return the number of bytes sent. (The format of address 从属地址族 — 见上文。)

socket. setblocking ( flag ) ¶

设置套接字的阻塞或非阻塞模式：若 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 recv() call doesn’t find any data, or if a send() call can’t immediately dispose of the data, an error exception is raised; in blocking mode, the calls block until they can proceed. s.setblocking(0) 相当于 s.settimeout(0.0) ; s.setblocking(1) 相当于 s.settimeout(None) .

socket. settimeout ( 值 ) ¶

设置阻塞套接字操作时的超时。 value argument can be a nonnegative float expressing seconds, or None . If a float is given, subsequent socket operations will raise a timeout 异常若超时周期 value has elapsed before the operation has completed. Setting a timeout of None disables timeouts on socket operations. s.settimeout(0.0) 相当于 s.setblocking(0) ; s.settimeout(None) 相当于 s.setblocking(1) .

2.3 版新增。

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() .

2.3 版新增。

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 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. In timeout mode, operations fail if they cannot be completed within the timeout specified for the socket or if the system returns an error. The setblocking() method is simply a shorthand for certain settimeout() 调用。

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 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.

注意， connect() operation is 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() . The system network stack may return a connection timeout error of its own regardless of any Python socket timeout setting.

socket. setsockopt ( level , optname , 值 ) ¶

设置给定套接字选项的值 (见 Unix 手册页 setsockopt(2) )。需要的符号常量的定义在 socket 模块 ( 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 struct for a way to encode C structures as strings).

socket. shutdown ( how ) ¶

关闭连接的一半 (或两半)。若 how is SHUT_RD ，禁止进一步接收。若 how is SHUT_WR ，禁止进一步发送。若 how is SHUT_RDWR , further sends and receives are disallowed. Depending on the platform, shutting down one half of the connection can also close the opposite half (e.g. on Mac OS X, shutdown(SHUT_WR) does not allow further reads on the other end of the connection).

注意，没有方法 read() or write() ；使用 recv() and send() without flags 自变量代替。

套接字对象还有这些 (只读) 属性，给出值对应 socket 构造函数。

socket. 系列 ¶

套接字系列。

2.5 版新增。

socket. type ¶

套接字类型。

2.5 版新增。

socket. proto ¶

套接字协议。

2.5 版新增。

17.2.2. 范例 ¶

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() .

前 2 范例仅支持 IPv4。

# 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.sendall(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.sendall('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 as msg:
        s = None
        continue
    try:
        s.bind(sa)
        s.listen(1)
    except socket.error as 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 as msg:
        s = None
        continue
    try:
        s.connect(sa)
    except socket.error as msg:
        s.close()
        s = None
        continue
    break
if s is None:
    print 'could not open socket'
    sys.exit(1)
s.sendall('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)
					

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

socket.error: [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.

有 socket 标志要设置，为阻止此 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.

内容表

• 17.2. socket — 低级网络接口
  • 17.2.1. Socket Objects
  • 17.2.2. Example

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