Added more comments and moved the read-privatekey-part after the read-config-part

asserver.py

@@ -31,16 +31,17 @@ class SSHServer(asyncssh.SSHServer):
 
     def validate_public_key(self, username: str, key: asyncssh.SSHKey) -> bool:
         try:
-            return config_clients[username].validate(key, "", "") is not None
+            return config_clients[username].validate(key, "", "") is not None # checks client key
         except:
             return False
 
 
 def broadcast(msg: str, use_stderr: bool = False):
+    # Broadcast a message to all connected clients
     assert type(msg) == str
     msg = msg.strip("\r\n")
     if use_stderr:
-        msg += "\r\n"
+        msg += "\r\n" # we need CRLF for stderr apparently
         for c in connected_clients:
             c.stderr.write(msg)
     else:
@@ -52,15 +53,18 @@ async def handle_connection(process: asyncssh.SSHServerProcess):
     connected_clients.append(process)
     username = process.get_extra_info("username")
     try:
+        # hello there
         connected_msg = f"[connected] {username}\n"
         stderr.write(connected_msg)
         broadcast(connected_msg, True)
         if process.command is not None:
+            # client has provided a command as a ssh commandline argument
             line = process.command.strip("\r\n")
             msg = f"{username}: {line}\n"
             stdout.write(msg)
             broadcast(msg)
         else:
+            # client wants an interactive session
             while True:
                 try:
                     async for line in process.stdin:
@@ -70,18 +74,19 @@ async def handle_connection(process: asyncssh.SSHServerProcess):
                         stdout.write(msg)
                         broadcast(msg)
                 except asyncssh.TerminalSizeChanged:
-                    continue
-                finally:
-                    break
+                    continue # we don't want to exit when the client changes its terminal size lol
+                finally:     # but otherwise, we do want to
+                    break    # exit this loop.
     except asyncssh.BreakReceived:
-        pass
+        pass # we don't want to write an error message on this exception
     except Exception as e:
         stderr.write(f"An error occured: {type(e).__name__} {e}\n")
         stderr.flush()
     finally:
+        # exit process, remove client from list, inform other clients
+        disconnected_msg = f"[disconnected] {username}\n"
         process.exit(0)
         connected_clients.remove(process)
-        disconnected_msg = f"[disconnected] {username}\n"
         stderr.write(disconnected_msg)
         broadcast(disconnected_msg, True)
 
@@ -97,11 +102,12 @@ if __name__ == "__main__":
     config_host = str(config["host"])
     config_port = int(config["port"])
     config_private_key = asyncssh.import_private_key(args.pkey.read_text())
+    for c in config["clients"]:
+        config_clients[str(c)] = asyncssh.import_authorized_keys(str(config["clients"][c]))
+    # read 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(