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"""
This server reads a message from a WebSocket, and sends the reverse string in a
response message. It can only handle one client at a time. This is a very bad
implementation of a server! It is only intended to demonstrate how to use
wsproto.
"""
import socket
import sys
from wsproto import ConnectionType, WSConnection
from wsproto.events import (
AcceptConnection,
CloseConnection,
Message,
Ping,
Request,
TextMessage,
)
MAX_CONNECTS = 5
RECEIVE_BYTES = 4096
def main() -> None:
"""Run the server."""
try:
ip = sys.argv[1]
port = int(sys.argv[2])
except (IndexError, ValueError):
print("Usage: {} <BIND_IP> <PORT>".format(sys.argv[0]))
sys.exit(1)
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server.bind((ip, port))
server.listen(0)
try:
while True:
print("Waiting for connection...")
(stream, addr) = server.accept()
print("Client connected: {}:{}".format(addr[0], addr[1]))
handle_connection(stream)
stream.shutdown(socket.SHUT_WR)
stream.close()
except KeyboardInterrupt:
print("Received SIGINT: shutting down…")
def handle_connection(stream: socket.socket) -> None:
"""
Handle a connection.
The server operates a request/response cycle, so it performs a synchronous
loop:
1) Read data from network into wsproto
2) Get new events and handle them
3) Send data from wsproto to network
:param stream: a socket stream
"""
ws = WSConnection(ConnectionType.SERVER)
running = True
while running:
# 1) Read data from network
in_data = stream.recv(RECEIVE_BYTES)
print("Received {} bytes".format(len(in_data)))
ws.receive_data(in_data)
# 2) Get new events and handle them
out_data = b""
for event in ws.events():
if isinstance(event, Request):
# Negotiate new WebSocket connection
print("Accepting WebSocket upgrade")
out_data += ws.send(AcceptConnection())
elif isinstance(event, CloseConnection):
# Print log message and break out
print(
"Connection closed: code={} reason={}".format(
event.code, event.reason
)
)
out_data += ws.send(event.response())
running = False
elif isinstance(event, TextMessage):
# Reverse text and send it back to wsproto
print("Received request and sending response")
out_data += ws.send(Message(data=event.data[::-1]))
elif isinstance(event, Ping):
# wsproto handles ping events for you by placing a pong frame in
# the outgoing buffer. You should not call pong() unless you want to
# send an unsolicited pong frame.
print("Received ping and sending pong")
out_data += ws.send(event.response())
else:
print(f"Unknown event: {event!r}")
# 4) Send data from wsproto to network
print("Sending {} bytes".format(len(out_data)))
stream.send(out_data)
if __name__ == "__main__":
main()
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