Socket編程進階8

Python之路,Day8 - Socket編程進階

本節內容：

1. Socket語法及相關
2. SocketServer實現多併發　

Socket語法及相關

socket概念

socket本質上就是在2臺網絡互通的電腦之間，架設一個通道，兩臺電腦通過這個通道來實現數據的互相傳遞。 我們知道網絡 通信 都 是基於 ip+port 方能定位到目標的具體機器上的具體服務，操作系統有0-65535個端口，每個端口都可以獨立對外提供服務，如果 把一個公司比做一臺電腦 ，那公司的總機號碼就相當於ip地址， 每個員工的分機號就相當於端口， 你想找公司某個人，必須 先打電話到總機，然後再轉分機 。

建立一個socket必須至少有2端， 一個服務端，一個客戶端， 服務端被動等待並接收請求，客戶端主動發起請求， 連接建立之後，雙方可以互發數據。

A network socket is an endpoint of a connection across a computer network. Today, most communication between computers is based on the Internet Protocol; therefore most network sockets are Internet sockets. More precisely, a socket is a handle (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, 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, that allows application programs to control and use network sockets. Internet socket APIs are usually based on the Berkeley sockets standard. In the Berkeley sockets standard, sockets are a form of file descriptor (a file handle), due to the 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 and a port number, much like one end of a telephone connection is the combination of a 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 or thread.

Socket Families(地址簇)

socket.AF_UNIX unix本機進程間通信

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 AF_UNIX 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，普通的套接字無法處理ICMP、IGMP等網絡報文，而SOCK_RAW可以；其次，SOCK_RAW也可以處理特殊的IPv4報文；此外，利用原始套接字，可以通過IP_HDRINCL套接字選項由用戶構造IP頭。

socket.SOCK_RDM

是一種可靠的UDP形式，即保證交付數據報但不保證順序。SOCK_RAM用來提供對原始協議的低級訪問，在需要執行某些特殊操作時使用，如發送ICMP報文。SOCK_RAM通常僅限於高級用戶或管理員運行的程序使用。

socket.SOCK_SEQPACKET

廢棄了

These constants represent the socket types, used for the second argument to socket(). More constants may be available depending on the system. (Only SOCK_STREAM and SOCK_DGRAM 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 AF_INET (the default), AF_INET6, AF_UNIX, AF_CAN or AF_RDS. The socket type should beSOCK_STREAM (the default), SOCK_DGRAM, SOCKRAW 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 or CAN_BCM. 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 AF_UNIX if defined on the platform; otherwise, the default is AF_INET.

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.

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) #獲取要連接的對端主機地址

sk.bind(address)

　　s.bind(address) 將套接字綁定到地址。address地址的格式取決於地址族。在AF_INET下，以元組（host,port）的形式表示地址。

sk.listen(backlog)

　　開始監聽傳入連接。backlog指定在拒絕連接之前，可以掛起的最大連接數量。

backlog等於5，表示內核已經接到了連接請求，但服務器還沒有調用accept進行處理的連接個數最大爲5

這個值不能無限大，因爲要在內核中維護連接隊列

sk.setblocking(bool)

　　是否阻塞（默認True），如果設置False，那麼accept和recv時一旦無數據，則報錯。

sk.accept()

　　接受連接並返回（conn,address）,其中conn是新的套接字對象，可以用來接收和發送數據。address是連接客戶端的地址。

　　接收TCP 客戶的連接（阻塞式）等待連接的到來

sk.connect(address)

　　連接到address處的套接字。一般，address的格式爲元組（hostname,port）,如果連接出錯，返回socket.error錯誤。

sk.connect_ex(address)

　　同上，只不過會有返回值，連接成功時返回 0 ，連接失敗時候返回編碼，例如：10061

sk.close()

　　關閉套接字

sk.recv(bufsize[,flag])

　　接受套接字的數據。數據以字符串形式返回，bufsize指定最多可以接收的數量。flag提供有關消息的其他信息，通常可以忽略。

sk.recvfrom(bufsize[.flag])

　　與recv()類似，但返回值是（data,address）。其中data是包含接收數據的字符串，address是發送數據的套接字地址。

sk.send(string[,flag])

　　將string中的數據發送到連接的套接字。返回值是要發送的字節數量，該數量可能小於string的字節大小。即：可能未將指定內容全部發送。

sk.sendall(string[,flag])

　　將string中的數據發送到連接的套接字，但在返回之前會嘗試發送所有數據。成功返回None，失敗則拋出異常。

內部通過遞歸調用send，將所有內容發送出去。

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

　　將數據發送到套接字，address是形式爲（ipaddr，port）的元組，指定遠程地址。返回值是發送的字節數。該函數主要用於UDP協議。

sk.settimeout(timeout)

　　設置套接字操作的超時期，timeout是一個浮點數，單位是秒。值爲None表示沒有超時期。一般，超時期應該在剛創建套接字時設置，因爲它們可能用於連接的操作（如 client 連接最多等待5s ）

sk.getpeername()

　　返回連接套接字的遠程地址。返回值通常是元組（ipaddr,port）。

sk.getsockname()

　　返回套接字自己的地址。通常是一個元組(ipaddr,port)

sk.fileno()

　　套接字的文件描述符

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

發送文件 ，但目前多數情況下並無什麼卵用。

SocketServer

The socketserver 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 BaseServer 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 TCPServer.

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 TCPServer.

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 ForkingMixIn and ThreadingMixIn 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 UnixDatagramServer derives from UDPServer, not from UnixStreamServer — 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, ThreadingUDPServer is created as follows:

class ThreadingUDPServer(ThreadingMixIn, UDPServer):
    pass

The mix-in class comes first, since it overrides a method defined in UDPServer. 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))

上面這個例子你會發現，依然不能實現多併發，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)

線程與進程

http://www.cnblogs.com/alex3714/articles/5230609.html 　　

主機管理之paramiko模塊學習

http://www.cnblogs.com/wupeiqi/articles/5095821.html

作業1：用socketserver繼續完善FTP作業

作業2：開發一個批量主機管理工具
需求：

1. 可以對機器進行分組
2. 可以對指定的一組或多組機器執行批量命令，分發文件(發送\接收)
3. 紀錄操作日誌

注：該文章由alex的blog搬運而來