本节内容:
Socket 语法及相关
SocketServer 实现多并发
Socket 语法及相关
socket 概念
socket 本质上就是在 2 台网络互通的电脑之间, 架设一个通道, 两台电脑通过这个通道来实现数据的互相传递. 我们知道网络 通信 都 是基于 ip+port 方能定位到目标的具体机器上的具体服务, 操作系统有 0-65535 个端口, 每个端口都可以独立对外提供服务, 如果 把一个公司比做一台电脑 , 那公司的总机号码就相当于 ip 地址, 每个员工的分机号就相当于端口, 你想找公司某个人, 必须 先打电话到总机, 然后再转分机 .
建立一个 socket 必须至少有 2 端, 一个服务端, 一个客户端, 服务端被动等待并接收请求, 客户端主动发起请求, 连接建立之后, 双方可以互发数据.
- A network socket is an endpoint of a connection across a computer network https://en.wikipedia.org/wiki/Computer_network . Today, most communication between computers is based on the Internet Protocol https://en.wikipedia.org/wiki/Internet_Protocol ; therefore most network sockets are Internet sockets. More precisely, a socket is a handle https://en.wikipedia.org/wiki/Handle_(computing) (abstract reference) that a local program can pass to the networking application programming interface (API) to use the connection, for example "send this data on this socket". Sockets are internally often simply integers https://en.wikipedia.org/wiki/Integer , which identify which connection to use.
- For example, to send "Hello, world!" via TCP to port 80 of the host with address 1.2.3.4, one might get a socket, connect it to the remote host, send the string, then close the socket:
- Socket socket = getSocket(type = "TCP")
- connect(socket, address = "1.2.3.4", port = "80")
- send(socket, "Hello, world!")
- close(socket)
- A socket API is an application programming interface (API), usually provided by the operating system https://en.wikipedia.org/wiki/Operating_system , that allows application programs to control and use network sockets. Internet socket APIs are usually based on the Berkeley sockets https://en.wikipedia.org/wiki/Berkeley_sockets standard. In the Berkeley sockets standard, sockets are a form of file descriptor https://en.wikipedia.org/wiki/File_descriptor (a file handle), due to the Unix philosophy https://en.wikipedia.org/wiki/Unix_philosophy that "everything is a file", and the analogies between sockets and files: you can read, write, open, and close both. In practice the differences mean the analogy is strained, and one instead use different interfaces (send and receive) on a socket. In inter-process communication, each end will generally have its own socket, but these may use different APIs: they are abstracted by the network protocol.
- A socket address is the combination of an IP address https://en.wikipedia.org/wiki/IP_address and a port number https://en.wikipedia.org/wiki/Port_number , much like one end of a telephone connection is the combination of a phone number https://en.wikipedia.org/wiki/Phone_number and a particular extension. Sockets need not have an address (for example for only sending data), but if a program binds a socket to an address, the socket can be used to receive data sent to that address. Based on this address, internet sockets deliver incoming data packets to the appropriate application process https://en.wikipedia.org/wiki/Process_(computing) or thread.
- Socket Families(地址簇)
socket.AF_UNIX unix 本机进程间通信
- socket.AF_INET IPV4
- socket.AF_INET6 IPV6
These constants represent the address (and protocol) families, used for the first argument to socket(). If the constant is not defined then this protocol is unsupported. More constants may be available depending on the system.
- Socket Types
- socket.SOCK_STREAM #for tcp
- socket.SOCK_DGRAM #for udp
- socket.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.
- socket.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.
- socket.SOCK_SEQPACKET #废弃了
- These constants represent the socket types, used for the second argument to socket(). More constants may be available depending on the system. (Only and appear to be generally useful.)
Socket 方法
- socket.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 (the default), , , or . The socket type should be (the default), , 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 the protocol should be one of CAN_RAW or . If fileno is specified, the other arguments are ignored, causing the socket with the specified file descriptor to return. Unlike socket.fromfd(), fileno will return the same socket and not a duplicate. This may help close a detached socket using socket.close().
socket.socketpair([family[, type[, proto]]])
Build a pair of connected socket objects using the given address family, socket type, and protocol number. Address family, socket type, and protocol number are as for the socket() function above. The default family is if defined on the platform; otherwise, the default is .
- 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 and , 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.
- Passing the optional timeout parameter will set the timeout on the socket instance before attempting to connect. If no timeout is supplied, the global default timeout setting returned by 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.
- socket.getaddrinfo(host, port, family=0, type=0, proto=0, flags=0) #获取要连接的对端主机地址
- sk.bind(address)
s.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.
sk.listen(backlog)
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
sk.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.
sk.accept()
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
sk.connect(address)
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.
sk.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
sk.close()
关闭套接字
sk.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.
sk.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.
sk.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.
sk.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.
sk.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.
sk.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 )
sk.getpeername()
返回连接套接字的远程地址. 返回值通常是元组(ipaddr,port).
sk.getsockname()
返回套接字自己的地址. 通常是一个元组(ipaddr,port)
sk.fileno()
套接字的文件描述符
socket.sendfile(file, offset=0, count=None)
发送文件 , 但目前多数情况下并无什么卵用.
SocketServer
The module simplifies the task of writing network servers.
- There are four basic concrete server classes:
- class socketserver.TCPServer
- (server_address, RequestHandlerClass, bind_and_activate=True)
This uses the Internet TCP protocol, which provides for continuous streams of data between the client and server. If bind_and_activate is true, the constructor automatically attempts to invoke server_bind() andserver_activate(). The other parameters are passed to the base class.
- class socketserver.UDPServer
- (server_address, RequestHandlerClass, bind_and_activate=True)
- This uses datagrams, which are discrete packets of information that may arrive out of order or be lost while in transit. The parameters are the same as for .
- class socketserver.UnixStreamServer
- (server_address, RequestHandlerClass, bind_and_activate=True)
- class socketserver.UnixDatagramServer
- (server_address, RequestHandlerClass,bind_and_activate=True)
- These more infrequently used classes are similar to the TCP and UDP classes, but use Unix domain sockets; they're not available on non-Unix platforms. The parameters are the same as for .
- These four classes process requests synchronously; each request must be completed before the next request can be started. This isn't suitable if each request takes a long time to complete, because it requires a lot of computation, or because it returns a lot of data which the client is slow to process. The solution is to create a separate process or thread to handle each request; the and mix-in classes can be used to support asynchronous behaviour.
- There are five classes in an inheritance diagram, four of which represent synchronous servers of four types:
- +------------+
- | BaseServer |
- +------------+
- |
- v
- +-----------+ +------------------+
- | TCPServer |------->| UnixStreamServer |
- +-----------+ +------------------+
- |
- v
- +-----------+ +--------------------+
- | UDPServer |------->| UnixDatagramServer |
- +-----------+ +--------------------+
- Note that derives from , not from - the only difference between an IP and a Unix stream server is the address family, which is simply repeated in both Unix server classes.
- class socketserver.ForkingMixIn
- class socketserver.ThreadingMixIn
- Forking and threading versions of each type of server can be created using these mix-in classes. For instance, is created as follows:
- class ThreadingUDPServer(ThreadingMixIn, UDPServer):
- pass
- The mix-in class comes first, since it overrides a method defined in . Setting the various attributes also changes the behavior of the underlying server mechanism.
- class socketserver.ForkingTCPServer
- class socketserver.ForkingUDPServer
- class socketserver.ThreadingTCPServer
- class socketserver.ThreadingUDPServer
- These classes are pre-defined using the mix-in classes.
- Request Handler Objects
- class socketserver.BaseRequestHandler
This is the superclass of all request handler objects. It defines the interface, given below. A concrete request handler subclass must define a new handle() method, and can override any of the other methods. A new instance of the subclass is created for each request.
- setup()
- Called before the handle() method to perform any initialization actions required. The default implementation does nothing.
- handle()
This function must do all the work required to service a request. The default implementation does nothing. Several instance attributes are available to it; the request is available as self.request; the client address as self.client_address; and the server instance as self.server, in case it needs access to per-server information.
- The type of self.request is different for datagram or stream services. For stream services,self.request is a socket object; for datagram services, self.request is a pair of string and socket.
- finish()
Called after the handle() method to perform any clean-up actions required. The default implementation does nothing. If setup() raises an exception, this function will not be called.
- socketserver.TCPServer
- Example
- server side
- import socketserver
- class MyTCPHandler(socketserver.BaseRequestHandler):
- """
- The request handler class for our server.
- It is instantiated once per connection to the server, and must
- override the handle() method to implement communication to the
- client.
- """
- def handle(self):
- # self.request is the TCP socket connected to the client
- self.data = self.request.recv(1024).strip()
- print("{} wrote:".format(self.client_address[0]))
- print(self.data)
- # just send back the same data, but upper-cased
- self.request.sendall(self.data.upper())
- if __name__ == "__main__":
- HOST, PORT = "localhost", 9999
- # Create the server, binding to localhost on port 9999
- server = socketserver.TCPServer((HOST, PORT), MyTCPHandler)
- # Activate the server; this will keep running until you
- # interrupt the program with Ctrl-C
- server.serve_forever()
- client side
- import socket
- import sys
- HOST, PORT = "localhost", 9999
- data = " ".join(sys.argv[1:])
- # Create a socket (SOCK_STREAM means a TCP socket)
- sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
- try:
- # Connect to server and send data
- sock.connect((HOST, PORT))
- sock.sendall(bytes(data + "\n", "utf-8"))
- # Receive data from the server and shut down
- received = str(sock.recv(1024), "utf-8")
- finally:
- sock.close()
- print("Sent: {}".format(data))
- print("Received: {}".format(received))
上面这个例子你会发现, 依然不能实现多并发, 哈哈, 在 server 端做一下更改就可以了
把
server = socketserver.TCPServer((HOST, PORT), MyTCPHandler)
改成
server = socketserver.ThreadingTCPServer((HOST, PORT), MyTCPHandler)
线程与进程
https://www.cnblogs.com/shuai1991/p/10920096.html
主机管理之 paramiko 模块学习
http://www.cnblogs.com/wupeiqi/articles/5095821.html
作业 1: 用 socketserver 继续完善 FTP 作业
作业 2: 开发一个批量主机管理工具
需求:
可以对机器进行分组
可以对指定的一组或多组机器执行批量命令, 分发文件(发送 \ 接收)
纪录操作日志
来源: http://www.bubuko.com/infodetail-3070528.html