【学习笔记：Python-网络编程】Socket 之初见

Socket 是任何一种计算机网络通讯中最基础的内容。当你在浏览器地址栏中输入一个地址时，你会打开一个套接字，可以说任何网络通讯都是通过 Socket 来完成的。

Socket 的 python 官方函数 http://docs.python.org/library/socket.html

socket和file的区别：

　　1、file模块是针对某个指定文件进行【打开】【读写】【关闭】

　　2、socket模块是针对 服务器端 和 客户端Socket 进行【打开】【读写】【关闭】

基本流程：

简单的一个端对端单线通信代码如下：

Server：

 # -*- coding:utf-8
 import socket
 sock = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
 sock.bind(("0.0.0.0",12800))
 sock.listen(2)
 while True:
     conn,sockname = sock.accept()
     print("Now,We have accepted a connection from:",sockname)
     print("Socket Name is:",conn.getsockname())
     print("Socket Peer is:",conn.getpeername())
     message = conn.recv(1024)
     print("The message we have received is:\n%s"%message)

Client：

# -*- coding:utf-8
import socket
sock = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
sock.connect(("127.0.0.1",12800))
sock.send(b"Hello World!")

参数解释：

 socket.socket(family=AF_INET, type=SOCK_STREAM, proto=0, fileno=None): 创建一个套接字对象，所有套接字操作基于此对象进行
　　family：套接字协议族，包括：有两种类型的套接字：基于文件的和面向网络的。AF表示地址家族（address family）
　　　　AF_UNIX：该套接字是基于文件的，一般用于本机通信
　　　　AF_INET：该套接字是基于网络的，这也是最常用的（默认） 　　
　　　　AF_INET6 ：用于第6 版因特网协议（IPv6）寻址

　 type：套接字类型，常用的有两种：
　　　　SOCK_STREAM：流式socket , for TCP （默认） 　　
　　　　SOCK_DGRAM：数据报式socket , for UDP

　　　　SOCK_RAW ：原始套接字，普通的套接字无法处理ICMP、IGMP等网络报文，而SOCK_RAW可以；其次，SOCK_RAW也可以处理特殊的IPv4报文；此外，利用原始套接字，可以通过IP_HDRINCL套接字选项由用户构造IP头。
　　　　SOCK_RDM ：是一种可靠的UDP形式，即保证交付数据报但不保证顺序。SOCK_RAM用来提供对原始协议的低级访问，在需要执行某些特殊操作时使用，如发送ICMP报文。SOCK_RAM通常仅限于高级用户或管理员运行的程序使用。
　　　　SOCK_SEQPACKET： 可靠的连续数据包服务

　 proto：协议，与特定的地址家族相关的协议,如果是 0 ,则系统就会根据地址格式和套接类别,自动选择一个合适的协议

sock.bind(address)

　　sock.bind(address) 将套接字绑定到地址。address地址的格式取决于地址族。在AF_INET下，以元组（host,port）的形式表示地址。

 

sock.listen(backlog)-- 服务端

　　开始监听传入连接。backlog指定在拒绝连接之前，可以挂起的最大连接数量。

    backlog等于5，表示内核已经接到了连接请求，但服务器还没有调用accept进行处理的连接个数最大为5
    这个值不能无限大，因为要在内核中维护连接队列，一般默认值为5

 

 

sock.settimeout(timeout)

 

　　设置套接字操作的超时期，timeout是一个浮点数，单位是秒。值为None表示没有超时期。一般，超时期应该在刚创建套接字时设置，因为它们可能用于连接的操作（如 client 连接最多等待5s ）

 

sock.getpeername()

 

　　返回连接套接字的远程地址。返回值通常是元组（ipaddr,port）。

 

sock.getsockname()

 

　　返回套接字自己的地址。通常是一个元组(ipaddr,port)

 

sock.fileno()

 

　　套接字的文件描述符

 

 

sock.setblocking(bool)

　　是否阻塞（默认True），如果设置False，那么accept和recv时一旦无数据，则报错。

sock.accept()-- 服务端

　　接受连接并返回（conn,address）,其中conn是新的套接字对象，可以用来接收和发送数据。address是连接客户端的地址。

　　接收TCP 客户的连接（阻塞式）等待连接的到来

sock.connect(address)-- 客户端

　　连接到address处的套接字。一般，address的格式为元组（hostname,port）,如果连接出错，返回socket.error错误。

sock.connect_ex(address)

　　同上，只不过会有返回值，连接成功时返回 0 ，连接失败时候返回编码，例如：10061

sock.close()

　　关闭套接字

 

 

sock.recv(bufsize[,flag])

　　接受套接字的数据。数据以字符串形式返回，bufsize指定最多可以接收的数量。flag提供有关消息的其他信息，通常可以忽略。

sock.recvfrom(bufsize[.flag])

　　与recv()类似，但返回值是（data,address）。其中data是包含接收数据的字符串，address是发送数据的套接字地址。

sock.send(string[,flag])

　　将string中的数据发送到连接的套接字。返回值是要发送的字节数量，该数量可能小于string的字节大小。即：可能未将指定内容全部发送。

sock.sendall(string[,flag])

　　将string中的数据发送到连接的套接字，但在返回之前会尝试发送所有数据。成功返回None，失败则抛出异常。

      内部通过递归调用send，将所有内容发送出去。

sock.sendto(string[,flag],address)

　　将数据发送到套接字，address是形式为（ipaddr，port）的元组，指定远程地址。返回值是发送的字节数。该函数主要用于UDP协议。

SocketType.__doc__

 class SocketType(__builtin__.object)
  |  socket([family[, type[, proto]]]) -> socket object
  |
  |  Open a socket of the given type.  The family argument specifies the
  |  address family; it defaults to AF_INET.  The type argument specifies
  |  whether this is a stream (SOCK_STREAM, this is the default)
  |  or datagram (SOCK_DGRAM) socket.  The protocol argument defaults to 0,
  |  specifying the default protocol.  Keyword arguments are accepted.
  |
  |  A socket object represents one endpoint of a network connection.
  |
  |  Methods of socket objects (keyword arguments not allowed):
  |
  |  accept() -- accept a connection, returning new socket and client address
  |  bind(addr) -- bind the socket to a local address
  |  close() -- close the socket
  |  connect(addr) -- connect the socket to a remote address
  |  connect_ex(addr) -- connect, return an error code instead of an exception
  |  dup() -- return a new socket object identical to the current one [*]
  |  fileno() -- return underlying file descriptor
  |  getpeername() -- return remote address [*]
  |  getsockname() -- return local address
  |  getsockopt(level, optname[, buflen]) -- get socket options
  |  gettimeout() -- return timeout or None
  |  listen(n) -- start listening for incoming connections
  |  makefile([mode, [bufsize]]) -- return a file object for the socket [*]
  |  recv(buflen[, flags]) -- receive data
  |  recv_into(buffer[, nbytes[, flags]]) -- receive data (into a buffer)
  |  recvfrom(buflen[, flags]) -- receive data and sender's address
  |  recvfrom_into(buffer[, nbytes, [, flags])
  |    -- receive data and sender's address (into a buffer)
  |  sendall(data[, flags]) -- send all data
  |  send(data[, flags]) -- send data, may not send all of it
  |  sendto(data[, flags], addr) -- send data to a given address
  |  setblocking(0 | 1) -- set or clear the blocking I/O flag
  |  setsockopt(level, optname, value) -- set socket options
  |  settimeout(None | float) -- set or clear the timeout
  |  shutdown(how) -- shut down traffic in one or both directions
  |
  |   [*] not available on all platforms!
  |
  |  Methods defined here:

  |
  |  accept(self)
  |      accept() -> (socket object, address info)
  |
  |      Wait for an incoming connection.  Return a new socket representing the
  |      connection, and the address of the client.  For IP sockets, the address
  |      info is a pair (hostaddr, port).
  |
  |  bind(self, address)

  |      bind(address)
  |
  |      Bind the socket to a local address.  For IP sockets, the address is a
  |      pair (host, port); the host must refer to the local host. For raw packet
  |      sockets the address is a tuple (ifname, proto [,pkttype [,hatype]])
  |
  |  close(self)
  |      close()
  |
  |      Close the socket.  It cannot be used after this call.
  |
  |  connect(self, address)
  |      connect(address)
  |
  |      Connect the socket to a remote address.  For IP sockets, the address
  |      is a pair (host, port).
  |
  |  connect_ex(self, address)
  |      connect_ex(address) -> errno
  |
  |      This is like connect(address), but returns an error code (the errno value)
  |      instead of raising an exception when an error occurs.
  |
  |  fileno(self)
  |      fileno() -> integer
  |
  |      Return the integer file descriptor of the socket.
  |
  |  getpeername(self)
  |      getpeername() -> address info
  |
  |      Return the address of the remote endpoint.  For IP sockets, the address
  |      info is a pair (hostaddr, port).
  |
  |  getsockname(self)
  |      getsockname() -> address info
  |
  |      Return the address of the local endpoint.  For IP sockets, the address
  |      info is a pair (hostaddr, port).
  |
  |  getsockopt(self, level, option, buffersize=None)
  |      getsockopt(level, option[, buffersize]) -> value
  |
  |      Get a socket option.  See the Unix manual for level and option.
  |      If a nonzero buffersize argument is given, the return value is a
  |      string of that length; otherwise it is an integer.
  |
  |  gettimeout(self)
  |      gettimeout() -> timeout
  |
  |      Returns the timeout in seconds (float) associated with socket
  |      operations. A timeout of None indicates that timeouts on socket
  |      operations are disabled.
  |
  |  ioctl(self, cmd, option)
  |      ioctl(cmd, option) -> long
  |
  |      Control the socket with WSAIoctl syscall. Currently supported 'cmd' values are
  |      SIO_RCVALL:  'option' must be one of the socket.RCVALL_* constants.
  |      SIO_KEEPALIVE_VALS:  'option' is a tuple of (onoff, timeout, interval).
  |
  |  listen(self, backlog)
  |      listen(backlog)
  |
  |      Enable a server to accept connections.  The backlog argument 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.
  |
  |  recv(self, buffersize, flags=None)
  |      recv(buffersize[, flags]) -> data
  |
  |      Receive up to buffersize bytes from the socket.  For the optional flags
  |      argument, see the Unix manual.  When no data is available, block until
  |      at least one byte is available or until the remote end is closed.  When
  |      the remote end is closed and all data is read, return the empty string.
  |
  |  recv_into(self, buffer, nbytes=None, flags=None)
  |      recv_into(buffer, [nbytes[, flags]]) -> nbytes_read
  |
  |      A version of recv() that stores its data into a buffer rather than creating
  |      a new string.  Receive up to buffersize bytes from the socket.  If buffersize
  |      is not specified (or 0), receive up to the size available in the given buffer.
  |
  |      See recv() for documentation about the flags.
  |
  |  recvfrom(self, buffersize, flags=None)
  |      recvfrom(buffersize[, flags]) -> (data, address info)
  |
  |      Like recv(buffersize, flags) but also return the sender's address info.
  |
  |  recvfrom_into(self, buffer, nbytes=None, flags=None)
  |      recvfrom_into(buffer[, nbytes[, flags]]) -> (nbytes, address info)
  |
  |      Like recv_into(buffer[, nbytes[, flags]]) but also return the sender's address info.
  |
  |  send(self, data, flags=None)
  |      send(data[, flags]) -> count
  |
  |      Send a data string to the socket.  For the optional flags
  |      argument, see the Unix manual.  Return the number of bytes
  |      sent; this may be less than len(data) if the network is busy.
  |
  |  sendall(self, data, flags=None)
  |      sendall(data[, flags])
  |
  |      Send a data string to the socket.  For the optional flags
  |      argument, see the Unix manual.  This calls send() repeatedly
  |      until all data is sent.  If an error occurs, it's impossible
  |      to tell how much data has been sent.
  |
  |  sendto(self, data, flags=None, *args, **kwargs)
  |      sendto(data[, flags], address) -> count
  |
  |      Like send(data, flags) but allows specifying the destination address.
  |      For IP sockets, the address is a pair (hostaddr, port).
  |
  |  setblocking(self, flag)
  |      setblocking(flag)
  |
  |      Set the socket to blocking (flag is true) or non-blocking (false).
  |      setblocking(True) is equivalent to settimeout(None);
  |      setblocking(False) is equivalent to settimeout(0.0).
  |
  |  setsockopt(self, level, option, value)
  |      setsockopt(level, option, value)
  |
  |      Set a socket option.  See the Unix manual for level and option.
  |      The value argument can either be an integer or a string.
  |
  |  settimeout(self, timeout)
  |      settimeout(timeout)
  |
  |      Set a timeout on socket operations.  'timeout' can be a float,
  |      giving in seconds, or None.  Setting a timeout of None disables
  |      the timeout feature and is equivalent to setblocking(1).
  |      Setting a timeout of zero is the same as setblocking(0).
  |
  |  shutdown(self, flag)
  |      shutdown(flag)
  |
  |      Shut down the reading side of the socket (flag == SHUT_RD), the writing side
  |      of the socket (flag == SHUT_WR), or both ends (flag == SHUT_RDWR).