107 lines
2.6 KiB
Python
107 lines
2.6 KiB
Python
import socket
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import threading
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import protocol
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import sys
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LOCAL_PORT = 9000
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TIMEOUT = 2 # 秒
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class StopWaitChat:
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def __init__(self, local_port, peer_addr):
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# IPv6 UDP socket
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self.sock = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
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# 绑定本地 IPv6 任意地址
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self.sock.bind(("::", local_port))
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# 设置 socket 超时（用于停等协议）
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self.sock.settimeout(TIMEOUT)
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self.peer_addr = peer_addr
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# 停等协议序号
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self.send_seq = 0
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self.recv_seq = 0
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def sender(self):
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"""
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发送线程（停等协议）
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"""
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while True:
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try:
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msg = input(">> ").encode()
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except EOFError:
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break
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pkt = protocol.make_packet(
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self.send_seq,
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protocol.TYPE_DATA,
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msg
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)
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# 停等：一直发，直到收到正确 ACK
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while True:
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self.sock.sendto(pkt, self.peer_addr)
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try:
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data, _ = self.sock.recvfrom(1024)
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seq, ptype, _ = protocol.parse_packet(data)
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if ptype == protocol.TYPE_ACK and seq == self.send_seq:
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# 正确 ACK
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self.send_seq ^= 1
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break
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except socket.timeout:
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print("[timeout] retransmit")
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def receiver(self):
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"""
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接收线程（必须捕获 timeout）
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"""
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while True:
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try:
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data, addr = self.sock.recvfrom(1024)
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except socket.timeout:
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continue
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seq, ptype, payload = protocol.parse_packet(data)
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if ptype == protocol.TYPE_DATA:
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if seq == self.recv_seq:
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print("\npeer:", payload.decode())
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self.recv_seq ^= 1
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# 无论是否重复，都返回 ACK
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ack = protocol.make_packet(seq, protocol.TYPE_ACK)
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self.sock.sendto(ack, addr)
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def main():
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if len(sys.argv) != 3:
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print("用法: python3 chat.py <对方IPv6地址或域名> <对方端口>")
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sys.exit(1)
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peer_ip = sys.argv[1]
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peer_port = int(sys.argv[2])
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chat = StopWaitChat(
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LOCAL_PORT,
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(peer_ip, peer_port)
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)
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# 启动接收线程
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recv_thread = threading.Thread(
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target=chat.receiver,
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daemon=True
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)
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recv_thread.start()
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# 主线程负责发送
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chat.sender()
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if __name__ == "__main__":
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main()
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