server: add docstrings

trezor_agent/server.py

@@ -1,3 +1,4 @@
+"""UNIX-domain socket server for ssh-agent implementation."""
 import contextlib
 import logging
 import os
@@ -14,6 +15,7 @@ UNIX_SOCKET_TIMEOUT = 0.1
 
 
 def remove_file(path, remove=os.remove, exists=os.path.exists):
+    """Remove file, and raise OSError if still exists."""
     try:
         remove(path)
     except OSError:
@@ -23,6 +25,11 @@ def remove_file(path, remove=os.remove, exists=os.path.exists):
 
 @contextlib.contextmanager
 def unix_domain_socket_server(sock_path):
+    """
+    Create UNIX-domain socket on specified path.
+
+    Listen on it, and delete it after the generated context is over.
+    """
     log.debug('serving on SSH_AUTH_SOCK=%s', sock_path)
     remove_file(sock_path)
 
@@ -36,6 +43,12 @@ def unix_domain_socket_server(sock_path):
 
 
 def handle_connection(conn, handler):
+    """
+    Handle a single connection using the specified protocol handler in a loop.
+
+    Exit when EOFError is raised.
+    All other exceptions are logged as warnings.
+    """
     try:
         log.debug('welcome agent')
         while True:
@@ -49,6 +62,12 @@ def handle_connection(conn, handler):
 
 
 def retry(func, exception_type, quit_event):
+    """
+    Run the function, retrying when the specified exception_type occurs.
+
+    Poll quit_event on each iteration, to be responsive to an external
+    exit request.
+    """
     while True:
         if quit_event.is_set():
             raise StopIteration
@@ -58,16 +77,17 @@ def retry(func, exception_type, quit_event):
             pass
 
 
-def server_thread(server, handler, quit_event):
+def server_thread(sock, handler, quit_event):
+    """Run a server on the specified socket."""
     log.debug('server thread started')
 
     def accept_connection():
-        conn, _ = server.accept()
+        conn, _ = sock.accept()
         conn.settimeout(None)
         return conn
 
     while True:
-        log.debug('waiting for connection on %s', server.getsockname())
+        log.debug('waiting for connection on %s', sock.getsockname())
         try:
             conn = retry(accept_connection, socket.timeout, quit_event)
         except StopIteration:
@@ -80,6 +100,7 @@ def server_thread(server, handler, quit_event):
 
 @contextlib.contextmanager
 def spawn(func, kwargs):
+    """Spawn a thread, and join it after the context is over."""
     t = threading.Thread(target=func, kwargs=kwargs)
     t.start()
     yield
@@ -88,14 +109,20 @@ def spawn(func, kwargs):
 
 @contextlib.contextmanager
 def serve(handler, sock_path=None, timeout=UNIX_SOCKET_TIMEOUT):
+    """
+    Start the ssh-agent server on a UNIX-domain socket.
+
+    If no connection is made during the specified timeout,
+    retry until the context is over.
+    """
     if sock_path is None:
         sock_path = tempfile.mktemp(prefix='ssh-agent-')
 
     environ = {'SSH_AUTH_SOCK': sock_path, 'SSH_AGENT_PID': str(os.getpid())}
-    with unix_domain_socket_server(sock_path) as server:
-        server.settimeout(timeout)
+    with unix_domain_socket_server(sock_path) as sock:
+        sock.settimeout(timeout)
         quit_event = threading.Event()
-        kwargs = dict(server=server, handler=handler, quit_event=quit_event)
+        kwargs = dict(sock=sock, handler=handler, quit_event=quit_event)
         with spawn(server_thread, kwargs):
             try:
                 yield environ
@@ -105,6 +132,11 @@ def serve(handler, sock_path=None, timeout=UNIX_SOCKET_TIMEOUT):
 
 
 def run_process(command, environ, use_shell=False):
+    """
+    Run the specified process and wait until it finishes.
+
+    Use environ dict for environment variables.
+    """
     log.info('running %r with %r', command, environ)
     env = dict(os.environ)
     env.update(environ)

trezor_agent/tests/test_server.py

@@ -71,7 +71,7 @@ def test_server_thread():
         def getsockname(self):  # pylint: disable=no-self-use
             return 'fake_server'
 
-    server.server_thread(server=FakeServer(),
+    server.server_thread(sock=FakeServer(),
                          handler=protocol.Handler(keys=[], signer=None),
                          quit_event=quit_event)