2018-03-20 12:32:41 +01:00
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import argparse
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import time
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import FPE
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# Let's define an app name. We'll use this for all
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# destinations we create. Since this echo example
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# is part of a range of example utilities, we'll put
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# them all within the app namespace "example_utilities"
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APP_NAME = "example_utilitites"
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# This initialisation is executed when the users chooses
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# to run as a server
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def server(configpath):
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# We must first initialise FlexPE
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fpe = FPE.FlexPE(configpath)
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# Randomly create a new identity for our echo server
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server_identity = FPE.Identity()
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# We create a destination that clients can query. We want
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# to be able to verify echo replies to our clients, so we
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# create a "single" destination that can receive encrypted
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# messages. This way the client can send a request and be
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# certain that no-one else than this destination was able
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# to read it.
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echo_destination = FPE.Destination(server_identity, FPE.Destination.IN, FPE.Destination.SINGLE, APP_NAME, "echo", "request")
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# Tell the destination which function in our program to
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# run when a packet is received.
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echo_destination.setCallback(serverCallback)
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# Everything's ready!
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# Let's Wait for client requests or user input
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announceLoop(echo_destination)
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def announceLoop(destination):
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# Let the user know that everything is ready
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2018-03-20 16:57:26 +01:00
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FPE.log("Echo server "+FPE.prettyhexrep(destination.hash)+" running, hit enter to send announce (Ctrl-C to quit)")
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2018-03-20 12:32:41 +01:00
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# We enter a loop that runs until the users exits.
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# If the user just hits enter, we will announce our server
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# destination on the network, which will let clients know
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# how to create messages directed towards it.
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while True:
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entered = raw_input()
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destination.announce()
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FPE.log("Sent announce from "+FPE.prettyhexrep(destination.hash))
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def serverCallback(message, packet):
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# We have received am echo request from a client! When
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# a client sends a request, it will include the hash of
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# it's identity in the message. Since we know that the
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# client has created a listening destination using this
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# identity hash, we can construct an outgoing destination
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# to direct our response to. The hash is sent in binary
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# format, so we encode it as printable hexadecimal first,
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# since aspect names need to in printable text.
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client_identity_hexhash = message.encode("hex_codec")
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# We can now create a destination that will let us reach
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# the client which send the echo request.
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reply_destination = FPE.Destination(None, FPE.Destination.OUT, FPE.Destination.PLAIN, APP_NAME, "echo", "reply", client_identity_hexhash)
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# Let's encode the reply destination hash in a readable
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# way, so we can output some info to the user.
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reply_destination_hexhash = reply_destination.hash.encode("hex_codec")
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# Tell the user that we received an echo request, and
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# that we are going to send a reply to the requester.
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FPE.log("Received packet from <"+reply_destination_hexhash+">, sending reply")
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# To let the client know that we got the echo request,
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# we will use the "proof" functions of FlexPE. In most
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# applications, the proving of packets will occur fully
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# automatically, but in some cases like this, it can be
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# beneficial to use the functions manually, since it
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# neatly provides functionality that can unequivocally
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# prove the receipt of the request to the client.
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#
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# Using the proof functionality is very simple, we just
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# need to call the "prove" method on the packet we wish
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# to prove, and specify which destination it should be
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# directed to.
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packet.prove(reply_destination)
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# We need a global list to hold sent echo requests
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sent_requests = []
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# This initialisation is executed when the users chooses
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# to run as a client
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def client(destination_hexhash, configpath):
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# We need a binary representation of the destination
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# hash that was entered on the command line
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try:
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if len(destination_hexhash) != 20:
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raise ValueError("Destination length is invalid, must be 20 hexadecimal characters (10 bytes)")
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destination_hash = destination_hexhash.decode("hex")
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except:
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FPE.log("Invalid destination entered. Check your input!")
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exit()
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# We must first initialise FlexPE
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2018-03-20 16:57:26 +01:00
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fpe = FPE.FlexPE(configpath)
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2018-03-20 12:32:41 +01:00
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# Randomly create a new identity for our echo server
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client_identity = FPE.Identity()
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# Let's set up a destination for replies to our echo
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# requests. This destination will be used by the server
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# to direct replies to. We're going to use a "plain"
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# destination, so the server can send replies back
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# without knowing any public keys of the client. In this
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# case, such a design is benificial, since any client
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# can send echo requests directly to the server, without
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# first having to announce it's destination, or include
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# public keys in the echo request
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#
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# We will use the destination naming convention of:
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# example_utilities.echo.reply.<IDENTITY_HASH>
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# where the last part is a hex representation of the hash
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# of our "client_identity". We need to include this to
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# create a unique destination for the server to respond to.
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# If we had used a "single" destination, something equivalent
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# to this process would have happened automatically.
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reply_destination = FPE.Destination(client_identity, FPE.Destination.IN, FPE.Destination.PLAIN, APP_NAME, "echo", "reply", client_identity.hexhash)
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# Since we are only expecting packets of the "proof"
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# type to reach our reply destination, we just set the
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# proof callback (and in this case not the normal
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# message callback)
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reply_destination.setProofCallback(clientProofCallback)
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# Tell the user that the client is ready!
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FPE.log("Echo client "+FPE.prettyhexrep(reply_destination.hash)+" ready, hit enter to send echo request (Ctrl-C to quit)")
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# We enter a loop that runs until the user exits.
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# If the user hits enter, we will try to send an
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# echo request to the destination specified on the
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# command line.
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while True:
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raw_input()
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# To address the server, we need to know it's public
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# key, so we check if FlexPE knows this destination.
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# This is done by calling the "recall" method of the
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# Identity module. If the destination is known, it will
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# return an Identity instance that can be used in
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# outgoing destinations.
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server_identity = FPE.Identity.recall(destination_hash)
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if server_identity != None:
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# We got the correct identity instance from the
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# recall method, so let's create an outgoing
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# destination. We use the naming convention:
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# example_utilities.echo.request
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# Since this is a "single" destination, the identity
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# hash will be automatically added to the end of
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# the name.
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request_destination = FPE.Destination(server_identity, FPE.Destination.OUT, FPE.Destination.SINGLE, APP_NAME, "echo", "request")
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# The destination is ready, so let's create a packet.
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# We set the destination to the request_destination
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# that was just created, and the only data we add
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# is the identity hash of our client identity.
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# Including that information will let the server
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# create a destination to send replies to.
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echo_request = FPE.Packet(request_destination, client_identity.hash)
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# Send the packet!
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echo_request.send()
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# Add the request to our list of sent packets
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sent_requests.append(echo_request)
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# Tell the user that the echo request was sent
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FPE.log("Sent echo request to "+FPE.prettyhexrep(request_destination.hash))
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else:
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# If we do not know this destination, tell the
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# user to wait for an announce to arrive.
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FPE.log("Destination is not yet known. Wait for an announce to arrive.")
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2018-04-04 10:35:21 +02:00
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# This method is called when our reply destination
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# receives a proof packet.
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2018-03-20 12:32:41 +01:00
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def clientProofCallback(proof_packet):
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2018-04-04 10:35:21 +02:00
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# We save the current time so we can calculate
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# round-trip time for the packet
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2018-03-20 12:32:41 +01:00
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now = time.time()
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2018-04-04 10:35:21 +02:00
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# Let's look through our list of sent requests,
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# and see if we can find one that matches the
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# proof we just received.
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2018-03-20 12:32:41 +01:00
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for unproven_packet in sent_requests:
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2018-04-04 10:35:21 +02:00
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try:
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# Check that the proof hash matches the
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# hash of the packet we sent earlier
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if unproven_packet.packet_hash == proof_packet.data[:32]:
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# We need to actually calidate the proof.
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# This is simply done by calling the
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# validateProofPacket method on the packet
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# we sent earlier.
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if unproven_packet.validateProofPacket(proof_packet):
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# If the proof is valid, we will calculate
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# the round-trip time, and inform the user.
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rtt = now - unproven_packet.sent_at
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if (rtt >= 1):
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rtt = round(rtt, 3)
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rttstring = str(rtt)+" seconds"
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else:
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rtt = round(rtt*1000, 3)
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rttstring = str(rtt)+" milliseconds"
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FPE.log(
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"Valid echo reply, proved by "+FPE.prettyhexrep(unproven_packet.destination.hash)+
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", round-trip time was "+rttstring
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)
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# Perform some cleanup
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sent_requests.remove(unproven_packet)
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del unproven_packet
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2018-03-20 12:32:41 +01:00
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else:
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2018-04-04 10:35:21 +02:00
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# If the proof was invalid, we inform
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# the user of this.
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FPE.log("Echo reply received, but proof was invalid")
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except:
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FPE.log("Proof packet received, but packet contained invalid or unparsable data")
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2018-03-20 12:32:41 +01:00
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if __name__ == "__main__":
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2018-04-04 10:35:21 +02:00
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# Set up command line arguments and start
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# the selected program mode.
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2018-03-20 12:32:41 +01:00
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try:
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parser = argparse.ArgumentParser(description="Simple echo server and client utility")
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parser.add_argument("-s", "--server", action="store_true", help="wait for incoming packets from clients")
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parser.add_argument("--config", action="store", default=None, help="path to alternative FlexPE config directory", type=str)
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parser.add_argument("destination", nargs="?", default=None, help="hexadecimal hash of the server destination", type=str)
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args = parser.parse_args()
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if args.server:
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configarg=None
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if args.config:
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configarg = args.config
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server(configarg)
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else:
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configarg=None
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if args.config:
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configarg = args.config
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client(args.destination, configarg)
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except KeyboardInterrupt:
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exit()
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