390 lines
13 KiB
Python
390 lines
13 KiB
Python
##########################################################
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# This RNS example demonstrates how to set up a link to #
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# a destination, and pass structured messages over it #
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# using a channel. #
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##########################################################
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import os
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import sys
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import time
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import argparse
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from datetime import datetime
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import RNS
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from RNS.vendor import umsgpack
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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_utilities"
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##########################################################
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#### Shared Objects ######################################
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##########################################################
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# Channel data must be structured in a subclass of
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# MessageBase. This ensures that the channel will be able
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# to serialize and deserialize the object and multiplex it
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# with other objects. Both ends of a link will need the
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# same object definitions to be able to communicate over
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# a channel.
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#
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# Note: The objects we wish to use over the channel must
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# be registered with the channel, and each link has a
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# different channel instance. See the client_connected
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# and link_established functions in this example to see
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# how message types are registered.
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# Let's make a simple message class called StringMessage
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# that will convey a string with a timestamp.
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class StringMessage(RNS.MessageBase):
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# The MSGTYPE class variable needs to be assigned a
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# 2 byte integer value. This identifier allows the
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# channel to look up your message's constructor when a
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# message arrives over the channel.
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#
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# MSGTYPE must be unique across all message types we
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# register with the channel. MSGTYPEs >= 0xf000 are
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# reserved for the system.
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MSGTYPE = 0x0101
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# The constructor of our object must be callable with
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# no arguments. We can have parameters, but they must
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# have a default assignment.
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#
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# This is needed so the channel can create an empty
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# version of our message into which the incoming
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# message can be unpacked.
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def __init__(self, data=None):
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self.data = data
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self.timestamp = datetime.now()
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# Finally, our message needs to implement functions
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# the channel can call to pack and unpack our message
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# to/from the raw packet payload. We'll use the
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# umsgpack package bundled with RNS. We could also use
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# the struct package bundled with Python if we wanted
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# more control over the structure of the packed bytes.
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#
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# Also note that packed message objects must fit
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# entirely in one packet. The number of bytes
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# available for message payloads can be queried from
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# the channel using the Channel.MDU property. The
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# channel MDU is slightly less than the link MDU due
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# to encoding the message header.
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# The pack function encodes the message contents into
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# a byte stream.
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def pack(self) -> bytes:
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return umsgpack.packb((self.data, self.timestamp))
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# And the unpack function decodes a byte stream into
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# the message contents.
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def unpack(self, raw):
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self.data, self.timestamp = umsgpack.unpackb(raw)
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##########################################################
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#### Server Part #########################################
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##########################################################
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# A reference to the latest client link that connected
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latest_client_link = None
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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 Reticulum
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reticulum = RNS.Reticulum(configpath)
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# Randomly create a new identity for our link example
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server_identity = RNS.Identity()
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# We create a destination that clients can connect to. We
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# want clients to create links to this destination, so we
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# need to create a "single" destination type.
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server_destination = RNS.Destination(
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server_identity,
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RNS.Destination.IN,
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RNS.Destination.SINGLE,
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APP_NAME,
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"channelexample"
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)
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# We configure a function that will get called every time
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# a new client creates a link to this destination.
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server_destination.set_link_established_callback(client_connected)
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# Everything's ready!
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# Let's Wait for client requests or user input
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server_loop(server_destination)
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def server_loop(destination):
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# Let the user know that everything is ready
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RNS.log(
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"Link example "+
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RNS.prettyhexrep(destination.hash)+
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" running, waiting for a connection."
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)
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RNS.log("Hit enter to manually send an announce (Ctrl-C to quit)")
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# We enter a loop that runs until the users exits.
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# If the user hits enter, we will announce our server
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# destination on the network, which will let clients
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# know how to create messages directed towards it.
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while True:
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entered = input()
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destination.announce()
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RNS.log("Sent announce from "+RNS.prettyhexrep(destination.hash))
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# When a client establishes a link to our server
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# destination, this function will be called with
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# a reference to the link.
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def client_connected(link):
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global latest_client_link
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latest_client_link = link
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RNS.log("Client connected")
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link.set_link_closed_callback(client_disconnected)
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# Register message types and add callback to channel
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channel = link.get_channel()
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channel.register_message_type(StringMessage)
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channel.add_message_handler(server_message_received)
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def client_disconnected(link):
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RNS.log("Client disconnected")
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def server_message_received(message):
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"""
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A message handler
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@param message: An instance of a subclass of MessageBase
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@return: True if message was handled
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"""
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global latest_client_link
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# When a message is received over any active link,
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# the replies will all be directed to the last client
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# that connected.
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# In a message handler, any deserializable message
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# that arrives over the link's channel will be passed
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# to all message handlers, unless a preceding handler indicates it
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# has handled the message.
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#
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#
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if isinstance(message, StringMessage):
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RNS.log("Received data on the link: " + message.data + " (message created at " + str(message.timestamp) + ")")
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reply_message = StringMessage("I received \""+message.data+"\" over the link")
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latest_client_link.get_channel().send(reply_message)
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# Incoming messages are sent to each message
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# handler added to the channel, in the order they
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# were added.
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# If any message handler returns True, the message
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# is considered handled and any subsequent
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# handlers are skipped.
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return True
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##########################################################
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#### Client Part #########################################
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##########################################################
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# A reference to the server link
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server_link = None
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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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dest_len = (RNS.Reticulum.TRUNCATED_HASHLENGTH//8)*2
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if len(destination_hexhash) != dest_len:
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raise ValueError(
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"Destination length is invalid, must be {hex} hexadecimal characters ({byte} bytes).".format(hex=dest_len, byte=dest_len//2)
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)
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destination_hash = bytes.fromhex(destination_hexhash)
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except:
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RNS.log("Invalid destination entered. Check your input!\n")
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exit()
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# We must first initialise Reticulum
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reticulum = RNS.Reticulum(configpath)
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# Check if we know a path to the destination
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if not RNS.Transport.has_path(destination_hash):
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RNS.log("Destination is not yet known. Requesting path and waiting for announce to arrive...")
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RNS.Transport.request_path(destination_hash)
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while not RNS.Transport.has_path(destination_hash):
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time.sleep(0.1)
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# Recall the server identity
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server_identity = RNS.Identity.recall(destination_hash)
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# Inform the user that we'll begin connecting
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RNS.log("Establishing link with server...")
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# When the server identity is known, we set
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# up a destination
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server_destination = RNS.Destination(
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server_identity,
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RNS.Destination.OUT,
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RNS.Destination.SINGLE,
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APP_NAME,
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"channelexample"
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)
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# And create a link
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link = RNS.Link(server_destination)
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# We'll also set up functions to inform the
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# user when the link is established or closed
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link.set_link_established_callback(link_established)
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link.set_link_closed_callback(link_closed)
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# Everything is set up, so let's enter a loop
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# for the user to interact with the example
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client_loop()
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def client_loop():
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global server_link
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# Wait for the link to become active
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while not server_link:
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time.sleep(0.1)
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should_quit = False
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while not should_quit:
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try:
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print("> ", end=" ")
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text = input()
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# Check if we should quit the example
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if text == "quit" or text == "q" or text == "exit":
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should_quit = True
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server_link.teardown()
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# If not, send the entered text over the link
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if text != "":
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message = StringMessage(text)
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packed_size = len(message.pack())
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channel = server_link.get_channel()
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if channel.is_ready_to_send():
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if packed_size <= channel.MDU:
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channel.send(message)
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else:
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RNS.log(
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"Cannot send this packet, the data size of "+
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str(packed_size)+" bytes exceeds the link packet MDU of "+
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str(channel.MDU)+" bytes",
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RNS.LOG_ERROR
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)
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else:
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RNS.log("Channel is not ready to send, please wait for " +
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"pending messages to complete.", RNS.LOG_ERROR)
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except Exception as e:
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RNS.log("Error while sending data over the link: "+str(e))
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should_quit = True
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server_link.teardown()
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# This function is called when a link
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# has been established with the server
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def link_established(link):
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# We store a reference to the link
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# instance for later use
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global server_link
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server_link = link
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# Register messages and add handler to channel
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channel = link.get_channel()
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channel.register_message_type(StringMessage)
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channel.add_message_handler(client_message_received)
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# Inform the user that the server is
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# connected
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RNS.log("Link established with server, enter some text to send, or \"quit\" to quit")
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# When a link is closed, we'll inform the
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# user, and exit the program
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def link_closed(link):
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if link.teardown_reason == RNS.Link.TIMEOUT:
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RNS.log("The link timed out, exiting now")
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elif link.teardown_reason == RNS.Link.DESTINATION_CLOSED:
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RNS.log("The link was closed by the server, exiting now")
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else:
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RNS.log("Link closed, exiting now")
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RNS.Reticulum.exit_handler()
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time.sleep(1.5)
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os._exit(0)
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# When a packet is received over the channel, we
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# simply print out the data.
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def client_message_received(message):
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if isinstance(message, StringMessage):
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RNS.log("Received data on the link: " + message.data + " (message created at " + str(message.timestamp) + ")")
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print("> ", end=" ")
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sys.stdout.flush()
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##########################################################
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#### Program Startup #####################################
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##########################################################
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# This part of the program runs at startup,
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# and parses input of from the user, and then
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# starts up the desired program mode.
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if __name__ == "__main__":
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try:
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parser = argparse.ArgumentParser(description="Simple channel example")
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parser.add_argument(
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"-s",
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"--server",
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action="store_true",
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help="wait for incoming link requests from clients"
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)
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parser.add_argument(
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"--config",
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action="store",
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default=None,
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help="path to alternative Reticulum config directory",
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type=str
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)
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parser.add_argument(
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"destination",
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nargs="?",
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default=None,
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help="hexadecimal hash of the server destination",
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type=str
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)
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args = parser.parse_args()
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if args.config:
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configarg = args.config
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else:
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configarg = None
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if args.server:
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server(configarg)
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else:
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if (args.destination == None):
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print("")
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parser.print_help()
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print("")
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else:
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client(args.destination, configarg)
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except KeyboardInterrupt:
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print("")
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exit() |