103 lines
3.2 KiB
Python
103 lines
3.2 KiB
Python
# PyDTLS sequential echo. Written by Ray Brown.
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"""PyDTLS sequential echo
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This script runs a sequential echo server. It is sequential in that it will
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respond without error only to a single sclient that invokes the following steps
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in order:
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* DTLS cookie exchange on port 28000 of localhost
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* DTLS handshake (application-default ciphers)
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* Write and receive echo back for an arbitrary number of datagrams
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* Isue shutdown notification and receive the shutdown notification response
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Note that this script's operation is slow and inefficient on purpose: it
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invokes the demux without socket select, but with 5-second timeouts after
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the cookie exchange; this is done so that one can follow the debug logs when
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operating this server from a client shell interactively.
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"""
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import socket
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from os import path
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from logging import basicConfig, DEBUG
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basicConfig(level=DEBUG) # set now for dtls import code
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from dtls.sslconnection import SSLConnection
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from dtls.err import SSLError, SSL_ERROR_WANT_READ, SSL_ERROR_ZERO_RETURN
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def main():
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sck = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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sck.bind(("127.0.0.1", 28000))
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sck.settimeout(30)
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cert_path = path.join(path.abspath(path.dirname(__file__)), "certs")
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scn = SSLConnection(
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sck,
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keyfile=path.join(cert_path, "server-key.pem"),
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certfile=path.join(cert_path, "server-cert.pem"),
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server_side=True,
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ca_certs=path.join(cert_path, "ca-cert.pem"),
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do_handshake_on_connect=False)
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cnt = 0
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while True:
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cnt += 1
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print "Listen invocation: %d" % cnt
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peer_address = scn.listen()
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if peer_address:
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print "Completed listening for peer: %s" % str(peer_address)
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break
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print "Accepting..."
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conn = scn.accept()[0]
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sck.settimeout(5)
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conn.get_socket(True).settimeout(5)
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cnt = 0
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while True:
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cnt += 1
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print "Listen invocation: %d" % cnt
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peer_address = scn.listen()
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assert not peer_address
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print "Handshake invocation: %d" % cnt
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try:
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conn.do_handshake()
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except SSLError as err:
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if len(err.args) > 1 and err.args[1].args[0] == SSL_ERROR_WANT_READ:
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continue
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raise
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print "Completed handshaking with peer"
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break
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cnt = 0
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while True:
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cnt += 1
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print "Listen invocation: %d" % cnt
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peer_address = scn.listen()
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assert not peer_address
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print "Read invocation: %d" % cnt
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try:
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message = conn.read()
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except SSLError as err:
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if err.args[0] == SSL_ERROR_WANT_READ:
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continue
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if err.args[0] == SSL_ERROR_ZERO_RETURN:
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break
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raise
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print message
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conn.write("Back to you: " + message)
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cnt = 0
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while True:
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cnt += 1
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print "Listen invocation: %d" % cnt
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peer_address = scn.listen()
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assert not peer_address
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print "Shutdown invocation: %d" % cnt
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try:
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conn.shutdown()
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except SSLError as err:
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if err.args[0] == SSL_ERROR_WANT_READ:
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continue
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raise
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break
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if __name__ == "__main__":
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main()
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