Add readme, add arg parse, fix proxy

README.md

@@ -0,0 +1,48 @@
+# FlexRadio Discovery Pakcet Proxy
+
+This project was created to allow connecting to a FlexRadio over a VPN as an
+alternative to using SmartLink.
+
+## Why?
+
+FlexRadio does not want to provide a way to connect to the radio by IP address.
+The only way to connect to the radio is by recieving a discovery packet from the radio.
+This is a problem if you want to connect to the radio from a different network when broadcast packets are not forwarded.
+
+## How?
+
+The proxy consists of two Python 3 scripts.
+
+`flex_proxy.py` is the main script that listens for discovery packets and forwards them to the client.
+It listens for UDP discovery packets on port 4992 and forwards the payload to all clients connected to the TCP socket on port 4996.
+
+`client.py` connects to the proxy via the TCP socket on port 4996. When a message is recieved, it re-broadcasts it as a UDP packet on port 4992.
+
+## Usage
+
+None of the two scripts require any external libraries.
+All libraries used are part of the Python 3 standard library:
+
+- `argparse`
+- `re`
+- `select`
+- `socket`
+- `sys`
+- `time`
+
+### Server
+
+```
+python3 flex_proxy.py
+```
+
+The TCP socket port can be changed by changing the `PORT` variable in `flex_proxy.py`.
+
+### Client
+
+```
+python3 client.py [ip address]
+```
+
+The default IP address is `localhost`.
+It can be changed by changing the `HOST` variable in `client.py` or by passing the IP address as an argument.

client.py

@@ -22,16 +22,50 @@ from socket import (
 )
 from select import select
 import sys
+from argparse import ArgumentParser
+import re
 
 SERVER = "localhost"
 PORT = 4996
 
+
+# Argument parsing
+serverRegex = r"^(?P<host>[^:]+)(:(?P<port>\d+))?$"
+
+parser = ArgumentParser(
+    prog="FlexRadio discovery proxy client",
+    description="Connect to a FlexRadio discovery proxy and re-broadcast all received packets",
+    epilog="Author: Jakob Kordež, S52KJ",
+)
+parser.add_argument(
+    "server",
+    metavar="SERVER",
+    type=str,
+    nargs="?",
+    default=SERVER,
+    help="Server address (default: %(default)s)",
+)
+
+args = parser.parse_args()
+sp = re.fullmatch(serverRegex, args.server)
+if not sp:
+    print("Invalid server address")
+    sys.exit(1)
+
+SERVER = sp.group("host")
+if sp.group("port"):
+    PORT = int(sp.group("port"))
+
+
+# Create broadcast socket
 broadcastSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)
 broadcastSocket.setsockopt(SOL_SOCKET, SO_BROADCAST, 1)
 
+
+# Connect to TCP server
 with socket(AF_INET, SOCK_STREAM) as s:
     s.settimeout(5)
-    print("Connecting to server...")
+    print("Connecting to server...", (SERVER, PORT))
 
     # Try to connect to the server for 5 seconds
     try:

flex_proxy.py

@@ -67,7 +67,7 @@ try:
                     except:
                         print("Client disconnected")
                     clients.remove(s)
-except KeyboardInterrupt:
+except:
     print("\nExiting...")
     for s in clients:
         s.close()