TCP操作小記

代碼位置

https://github.com/duganlx/fopnp/tree/m/py3

簡單的TCP服務器和客戶端

文件位置：fopnp/py3/chapter03/tcp_sixteen.py

import argparse, socket


def recvall(sock, length):
    data = b''
    while len(data) < length:
        more = sock.recv(length - len(data))
        if not more:
            raise EOFError('was expecting %d bytes but only received'
                           ' %d bytes before the socket closed'
                           % (length, len(data)))
        data += more
    return data


def server(interface, port):
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    sock.bind((interface, port))
    sock.listen(1)
    print('Listening at', sock.getsockname())
    while True:
        print('Waiting to accept a new connection')
        sc, sockname = sock.accept()
        print('We have accepted a connection from', sockname)
        print('  Socket name:', sc.getsockname())
        print('  Socket peer:', sc.getpeername())
        message = recvall(sc, 16)
        print('  Incoming sixteen-octet message:', repr(message))
        sc.sendall(b'Farewell, client')
        sc.close()
        print('  Reply sent, socket closed')


def client(host, port):
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.connect((host, port))
    print('Client has been assigned socket name', sock.getsockname())
    sock.sendall(b'Hi there, server')
    reply = recvall(sock, 16)
    print('The server said', repr(reply))
    sock.close()


if __name__ == '__main__':
    choices = {'client': client, 'server': server}
    parser = argparse.ArgumentParser(description='Send and receive over TCP')
    parser.add_argument('role', choices=choices, help='which role to play')
    parser.add_argument('host', help='interface the server listens at;'
                                     ' host the client sends to')
    parser.add_argument('-p', metavar='PORT', type=int, default=1060,
                        help='TCP port (default 1060)')
    args = parser.parse_args()
    function = choices[args.role]
    function(args.host, args.p)

運行效果

# cmd1
python tcp_sixteen.py server ""
Listening at ('0.0.0.0', 1060)
Waiting to accept a new connection
We have accepted a connection from ('127.0.0.1', 13857)
  Socket name: ('127.0.0.1', 1060)
  Socket peer: ('127.0.0.1', 13857)
  Incoming sixteen-octet message: b'Hi there, server'
  Reply sent, socket closed
Waiting to accept a new connection

# cmd2
python tcp_sixteen.py client 127.0.0.1
Client has been assigned socket name ('127.0.0.1', 13857)
The server said b'Farewell, client'

可能造成死鎖的TCP服務器和客戶端

文件位置：fopnp/py3/chapter03/tcp_deadlock.py

import argparse, socket, sys


def server(host, port):
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    sock.bind((host, port))
    sock.listen(1)
    print('Listening at', sock.getsockname())
    while True:
        sc, sockname = sock.accept()
        print('Processing up to 1024 bytes at a time from', sockname)
        n = 0
        while True:
            data = sc.recv(1024)
            if not data:
                break
            output = data.decode('ascii').upper().encode('ascii')
            sc.sendall(output)  # send it back uppercase
            n += len(data)
            print('\r  %d bytes processed so far' % (n,), end=' ')
            sys.stdout.flush()
        print()
        sc.close()
        print('  Socket closed')


def client(host, port, bytecount):
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    bytecount = (bytecount + 15) // 16 * 16  # round up to a multiple of 16
    message = b'capitalize this!'  # 16-byte message to repeat over and over

    print('Sending', bytecount, 'bytes of data, in chunks of 16 bytes')
    sock.connect((host, port))

    sent = 0
    while sent < bytecount:
        sock.sendall(message)
        sent += len(message)
        print('\r  %d bytes sent' % (sent,), end=' ')
        sys.stdout.flush()

    print()
    sock.shutdown(socket.SHUT_WR)

    print('Receiving all the data the server sends back')

    received = 0
    while True:
        data = sock.recv(42)
        if not received:
            print('  The first data received says', repr(data))
        if not data:
            break
        received += len(data)
        print('\r  %d bytes received' % (received,), end=' ')

    print()
    sock.close()


if __name__ == '__main__':
    roles = ('client', 'server')
    parser = argparse.ArgumentParser(description='Get deadlocked over TCP')
    parser.add_argument('role', choices=roles, help='which role to play')
    parser.add_argument('host', help='interface the server listens at;'
                                     ' host the client sends to')
    parser.add_argument('bytecount', type=int, nargs='?', default=16,
                        help='number of bytes for client to send (default 16)')
    parser.add_argument('-p', metavar='PORT', type=int, default=1060,
                        help='TCP port (default 1060)')
    args = parser.parse_args()
    if args.role == 'client':
        client(args.host, args.p, args.bytecount)
    else:
        server(args.host, args.p)

運行效果

# cmd1
python tcp_deadlock.py server ""
Listening at ('0.0.0.0', 1060)
Processing up to 1024 bytes at a time from ('127.0.0.1', 13918)
  195760 bytes processed so far

# cmd2
python tcp_deadlock.py client 127.0.0.1 160000000
Sending 160000000 bytes of data, in chunks of 16 bytes
  391552 bytes sent