Add echo demo

examples/echo/echo.py

@@ -0,0 +1,141 @@
+import argparse
+import asyncio
+import urllib.request
+
+import multiaddr
+
+from libp2p import new_node
+from libp2p.crypto.secp256k1 import create_new_key_pair
+from libp2p.network.stream.net_stream_interface import INetStream
+from libp2p.peer.peerinfo import info_from_p2p_addr
+from libp2p.typing import TProtocol
+
+PROTOCOL_ID = TProtocol("/echo/1.0.0")
+
+
+async def _echo_stream_handler(stream: INetStream) -> None:
+    msg = await stream.read()
+    await stream.write(msg)
+    await stream.close()
+
+
+async def run(port: int, destination: str, localhost: bool, seed: int = None) -> None:
+    if localhost:
+        ip = "127.0.0.1"
+    else:
+        ip = urllib.request.urlopen("https://v4.ident.me/").read().decode("utf8")
+    transport_opt = f"/ip4/{ip}/tcp/{port}"
+
+    if seed:
+        import random
+
+        random.seed(seed)
+        secret_number = random.getrandbits(32 * 8)
+        secret = secret_number.to_bytes(length=32, byteorder="big")
+    else:
+        import secrets
+
+        secret = secrets.token_bytes(32)
+
+    host = await new_node(
+        key_pair=create_new_key_pair(secret), transport_opt=[transport_opt]
+    )
+
+    print(f"I am {host.get_id().to_string()}")
+
+    await host.get_network().listen(multiaddr.Multiaddr(transport_opt))
+
+    if not destination:  # its the server
+
+        host.set_stream_handler(PROTOCOL_ID, _echo_stream_handler)
+
+        localhost_opt = " --localhost" if localhost else ""
+
+        print(
+            f"Run 'python ./examples/echo/echo.py"
+            + localhost_opt
+            + f" -p {int(port) + 1} -d /ip4/{ip}/tcp/{port}/p2p/{host.get_id().pretty()}'"
+            + " on another console."
+        )
+        print("Waiting for incoming connections...")
+
+    else:  # its the client
+        maddr = multiaddr.Multiaddr(destination)
+        info = info_from_p2p_addr(maddr)
+        # Associate the peer with local ip address
+        await host.connect(info)
+
+        # Start a stream with the destination.
+        # Multiaddress of the destination peer is fetched from the peerstore using 'peerId'.
+        stream = await host.new_stream(info.peer_id, [PROTOCOL_ID])
+
+        msg = b"hi, there!\n"
+
+        await stream.write(msg)
+        response = await stream.read()
+
+        print(f"Sent: {msg}")
+        print(f"Got: {response}")
+
+        await stream.close()
+
+
+def main() -> None:
+    description = """
+    This program demonstrates a simple echo protocol where a peer listens for
+    connections and copies back any input received on a stream.
+
+    To use it, first run 'python ./echo -p <PORT>', where <PORT> is the port number.
+    Then, run another host with 'python ./chat -p <ANOTHER_PORT> -d <DESTINATION>',
+    where <DESTINATION> is the multiaddress of the previous listener host.
+    """
+    example_maddr = (
+        "/ip4/127.0.0.1/tcp/8000/p2p/QmQn4SwGkDZKkUEpBRBvTmheQycxAHJUNmVEnjA2v1qe8Q"
+    )
+    parser = argparse.ArgumentParser(description=description)
+    parser.add_argument(
+        "--debug",
+        action="store_true",
+        help="generate the same node ID on every execution",
+    )
+    parser.add_argument(
+        "-p", "--port", default=8000, type=int, help="source port number"
+    )
+    parser.add_argument(
+        "-d",
+        "--destination",
+        type=str,
+        help=f"destination multiaddr string, e.g. {example_maddr}",
+    )
+    parser.add_argument(
+        "-l",
+        "--localhost",
+        dest="localhost",
+        action="store_true",
+        help="flag indicating if localhost should be used or an external IP",
+    )
+    parser.add_argument(
+        "-s",
+        "--seed",
+        type=int,
+        help="provide a seed to the random number generator (e.g. to fix peer IDs across runs)",
+    )
+    args = parser.parse_args()
+
+    if not args.port:
+        raise RuntimeError("was not able to determine a local port")
+
+    loop = asyncio.get_event_loop()
+    try:
+        asyncio.ensure_future(
+            run(args.port, args.destination, args.localhost, args.seed)
+        )
+        loop.run_forever()
+    except KeyboardInterrupt:
+        pass
+    finally:
+        loop.close()
+
+
+if __name__ == "__main__":
+    main()