Added link example

Examples/Link.py

@@ -0,0 +1,232 @@
+##########################################################
+# This RNS example demonstrates how to set up a link to  #
+# a destination, and pass data back and forth over it.   #
+##########################################################
+
+import os
+import sys
+import time
+import argparse
+import RNS
+
+# Let's define an app name. We'll use this for all
+# destinations we create. Since this echo example
+# is part of a range of example utilities, we'll put
+# them all within the app namespace "example_utilities"
+APP_NAME = "example_utilitites"
+
+##########################################################
+#### Server Part #########################################
+##########################################################
+
+# A reference to the latest client link that connected
+latest_client_link = None
+
+# This initialisation is executed when the users chooses
+# to run as a server
+def server(configpath):
+	# We must first initialise Reticulum
+	reticulum = RNS.Reticulum(configpath)
+	
+	# Randomly create a new identity for our link example
+	server_identity = RNS.Identity()
+
+	# We create a destination that clients can connect to. We
+	# want clients to create links to this destination, so we
+	# need to create a "single" destination type.
+	server_destination = RNS.Destination(server_identity, RNS.Destination.IN, RNS.Destination.SINGLE, APP_NAME, "linkexample")
+
+	# We configure a function that will get called every time
+	# a new client creates a link to this destination.
+	server_destination.link_established_callback(client_connected)
+
+	# Everything's ready!
+	# Let's Wait for client requests or user input
+	server_loop(server_destination)
+
+def server_loop(destination):
+	# Let the user know that everything is ready
+	RNS.log("Link example "+RNS.prettyhexrep(destination.hash)+" running, waiting for a connection.")
+	RNS.log("Hit enter to manually send an announce (Ctrl-C to quit)")
+
+	# We enter a loop that runs until the users exits.
+	# If the user hits enter, we will announce our server
+	# destination on the network, which will let clients
+	# know how to create messages directed towards it.
+	while True:
+		entered = input()
+		destination.announce()
+		RNS.log("Sent announce from "+RNS.prettyhexrep(destination.hash))
+
+# When a client establishes a link to our server
+# destination, this function will be called with
+# a reference to the link.
+def client_connected(link):
+	global latest_client_link
+
+	RNS.log("Client connected")
+	link.link_closed_callback(client_disconnected)
+	link.packet_callback(server_packet_received)
+	latest_client_link = link
+
+def client_disconnected(link):
+	RNS.log("Client disconnected")
+
+def server_packet_received(message, packet):
+	global latest_client_link
+
+	text = message.decode("utf-8")
+	RNS.log("Received data on the link: "+text)
+	
+	reply_text = "I got \""+text+"\" from you"
+	reply_data = reply_text.encode("utf-8")
+	RNS.Packet(latest_client_link, reply_data).send()
+
+
+##########################################################
+#### Client Part #########################################
+##########################################################
+
+# A reference to the server link
+server_link = None
+
+# This initialisation is executed when the users chooses
+# to run as a client
+def client(destination_hexhash, configpath):
+	# We need a binary representation of the destination
+	# hash that was entered on the command line
+	try:
+		if len(destination_hexhash) != 20:
+			raise ValueError("Destination length is invalid, must be 20 hexadecimal characters (10 bytes)")
+		destination_hash = bytes.fromhex(destination_hexhash)
+	except:
+		RNS.log("Invalid destination entered. Check your input!\n")
+		exit()
+
+	# We must first initialise Reticulum
+	reticulum = RNS.Reticulum(configpath)
+
+	# Check if we know a path to the destination
+	if not RNS.Transport.hasPath(destination_hash):
+		RNS.log("Destination is not yet known. Requesting path and waiting for announce to arrive...")
+		RNS.Transport.requestPath(destination_hash)
+		while not RNS.Transport.hasPath(destination_hash):
+			time.sleep(0.1)
+
+	# Recall the server identity
+	server_identity = RNS.Identity.recall(destination_hash)
+
+	# Inform the user that we'll begin connecting
+	RNS.log("Establishing link with server...")
+
+	# When the server identity is known, we set
+	# up a destination
+	server_destination = RNS.Destination(server_identity, RNS.Destination.OUT, RNS.Destination.SINGLE, APP_NAME, "linkexample")
+
+	# And create a link
+	link = RNS.Link(server_destination)
+
+	# We set a callback that will get executed
+	# every time a packet is received over the
+	# link
+	link.packet_callback(client_packet_received)
+
+	# We'll also set up functions to inform the
+	# user when the link is established or closed
+	link.link_established_callback(link_established)
+	link.link_closed_callback(link_closed)
+
+	# Everything is set up, so let's enter a loop
+	# for the user to interact with the example
+	client_loop()
+
+def client_loop():
+	global server_link
+
+	# Wait for the link to become active
+	while not server_link:
+		time.sleep(0.1)
+
+	should_quit = False
+	while not should_quit:
+		print("> ", end=" ")
+		text = input()
+
+		# Check if we should quit the example
+		if text == "quit" or text == "q" or text == "exit":
+			should_quit = True
+			server_link.teardown()
+
+		# If not, send the entered text over the link
+		if text != "":
+			data = text.encode("utf-8")
+			RNS.Packet(server_link, data).send()
+
+# This function is called when a link
+# has been established with the server
+def link_established(link):
+	# We store a reference to the link
+	# instance for later use
+	global server_link
+	server_link = link
+
+	# Inform the user that the server is
+	# connected
+	RNS.log("Link established with server, enter some text to send, or \"quit\" to quit")
+
+# When a link is closed, we'll inform the
+# user, and exit the program
+def link_closed(link):
+	if link.teardown_reason == RNS.Link.TIMEOUT:
+		RNS.log("The link timed out, exiting now")
+	elif link.teardown_reason == RNS.Link.DESTINATION_CLOSED:
+		RNS.log("The link was closed by the server, exiting now")
+	else:
+		RNS.log("Link closed, exiting now")
+	
+	RNS.Reticulum.exit_handler()
+	time.sleep(1.5)
+	os._exit(0)
+
+# When a packet is received over the link, we
+# simply print out the data.
+def client_packet_received(message, packet):
+	text = message.decode("utf-8")
+	RNS.log("Received data on the link: "+text)
+	print("> ", end=" ")
+	sys.stdout.flush()
+
+
+##########################################################
+#### Program Startup #####################################
+##########################################################
+
+# This part of the program runs at startup,
+# and parses input of from the user, and then
+# starts up the desired program mode.
+if __name__ == "__main__":
+	try:
+		parser = argparse.ArgumentParser(description="Simple link example")
+		parser.add_argument("-s", "--server", action="store_true", help="wait for incoming link requests from clients")
+		parser.add_argument("--config", action="store", default=None, help="path to alternative Reticulum config directory", type=str)
+		parser.add_argument("destination", nargs="?", default=None, help="hexadecimal hash of the server destination", type=str)
+		args = parser.parse_args()
+
+		if args.config:
+			configarg = args.config
+		else:
+			configarg = None
+
+		if args.server:
+			server(configarg)
+		else:
+			if (args.destination == None):
+				print("")
+				parser.print_help()
+				print("")
+			else:
+				client(args.destination, configarg)
+
+	except KeyboardInterrupt:
+		print("")
+		exit()