Add project files

asserver.py

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+#!/usr/bin/env python3
+
+# Copyright (c) 2024 Julian Müller (ChaoticByte)
+# License: MIT
+
+import asyncio
+
+from argparse import ArgumentParser
+from pathlib import Path
+from sys import stdout
+from sys import stderr
+
+import asyncssh
+import yaml
+
+
+config_host = ""
+config_port = 8022
+connected_clients = []
+config_clients = {
+    # username: asyncssh.SSHAuthorizedKeys
+}
+
+
+class SSHServer(asyncssh.SSHServer):
+    def host_based_auth_supported(self): return False
+    def kbdint_auth_supported(self): return False
+    def password_auth_supported(self): return False
+    def public_key_auth_supported(self): return True
+    def begin_auth(self, username: str) -> bool: return True # we wanna handle auth
+
+    def validate_public_key(self, username: str, key: asyncssh.SSHKey) -> bool:
+        try:
+            return config_clients[username].validate(key, "", "") is not None
+        except:
+            return False
+
+
+def broadcast(msg: str):
+    assert type(msg) == str
+    for c in connected_clients:
+        c.stdout.write(msg)
+
+async def handle_connection(process: asyncssh.SSHServerProcess):
+    connected_clients.append(process)
+    username = process.get_extra_info("username")
+    try:
+        connected_msg = f"[connected] {username}\n"
+        stdout.write(connected_msg)
+        broadcast(connected_msg)
+        while True:
+            try:
+                async for line in process.stdin:
+                    if line == "": raise asyncssh.BreakReceived(0)
+                    line = line.strip('\n\r')
+                    msg = f"{username}: {line}\n"
+                    stdout.write(msg)
+                    broadcast(msg)
+            except asyncssh.TerminalSizeChanged:
+                continue
+            finally:
+                break
+    except asyncssh.BreakReceived:
+        pass
+    except Exception as e:
+        stderr.write(f"An error occured: {type(e).__name__} {e}\n")
+        stderr.flush()
+    finally:
+        process.exit(0)
+        connected_clients.remove(process)
+        disconnected_msg = f"[disconnected] {username}\n"
+        stdout.write(disconnected_msg)
+        broadcast(disconnected_msg)
+
+
+if __name__ == "__main__":
+    # commandline arguments
+    argp = ArgumentParser()
+    argp.add_argument("config", type=Path, help="The path to the config file")
+    args = argp.parse_args()
+    # read config
+    config = yaml.safe_load(args.config.read_text())
+    config_host = str(config["host"])
+    config_port = int(config["port"])
+    config_private_key = asyncssh.import_private_key(config["private_key"])
+    server_public_key = config_private_key.export_public_key("openssh").decode().strip("\n\r")
+    stderr.write(f"Server public key is \"{server_public_key}\"\n")
+    stderr.flush()
+    for c in config["clients"]:
+        config_clients[str(c)] = asyncssh.import_authorized_keys(str(config["clients"][c]))
+    # start server
+    loop = asyncio.get_event_loop()
+    loop.run_until_complete(
+        asyncssh.create_server(
+            SSHServer,
+            config_host,
+            config_port,
+            server_host_keys=[config_private_key],
+            process_factory=handle_connection
+        ))
+    loop.run_forever()