extmod/uasyncio: Get addr and bind server socket before creating task.

dpgeorge · dpgeorge · commit 7ec95c276879 · 2021-06-26T22:30:22.000+10:00
Currently when using uasyncio.start_server() the socket configuration is done inside a uasyncio.create_task() background function. If the address and port are already in use however this throws an OSError which cannot be cleanly caught behind the create_task(). This commit moves the getaddrinfo and socket binding to the start_server() function, and only creates the task if that succeeds. This means that any OSError from the initial socket configuration is propagated directly up the call stack, compatible with CPython behaviour. See adafruit#7444. Signed-off-by: Damien George <damien@micropython.org>
diff --git a/extmod/uasyncio/stream.py b/extmod/uasyncio/stream.py
@@ -107,15 +107,7 @@ def close(self):
     async def wait_closed(self):
         await self.task
 
-    async def _serve(self, cb, host, port, backlog):
-        import usocket as socket
-
-        ai = socket.getaddrinfo(host, port)[0]  # TODO this is blocking!
-        s = socket.socket()
-        s.setblocking(False)
-        s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-        s.bind(ai[-1])
-        s.listen(backlog)
+    async def _serve(self, s, cb):
         # Accept incoming connections
         while True:
             try:
@@ -137,9 +129,20 @@ async def _serve(self, cb, host, port, backlog):
 # Helper function to start a TCP stream server, running as a new task
 # TODO could use an accept-callback on socket read activity instead of creating a task
 async def start_server(cb, host, port, backlog=5):
-    s = Server()
-    s.task = core.create_task(s._serve(cb, host, port, backlog))
-    return s
+    import usocket as socket
+
+    # Create and bind server socket.
+    host = socket.getaddrinfo(host, port)[0]  # TODO this is blocking!
+    s = socket.socket()
+    s.setblocking(False)
+    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    s.bind(host[-1])
+    s.listen(backlog)
+
+    # Create and return server object and task.
+    srv = Server()
+    srv.task = core.create_task(srv._serve(s, cb))
+    return srv
 
 
 ################################################################################
diff --git a/tests/net_hosted/uasyncio_start_server.py b/tests/net_hosted/uasyncio_start_server.py
@@ -0,0 +1,31 @@
+# Test basic behaviour of uasyncio.start_server()
+
+try:
+    import uasyncio as asyncio
+except ImportError:
+    try:
+        import asyncio
+    except ImportError:
+        print("SKIP")
+        raise SystemExit
+
+
+async def test():
+    # Test creating 2 servers using the same address
+    print("create server1")
+    server1 = await asyncio.start_server(None, "0.0.0.0", 8000)
+    try:
+        print("create server2")
+        await asyncio.start_server(None, "0.0.0.0", 8000)
+    except OSError as er:
+        print("OSError")
+
+    # Wait for server to close.
+    async with server1:
+        print("sleep")
+        await asyncio.sleep(0)
+
+    print("done")
+
+
+asyncio.run(test())
diff --git a/tests/net_hosted/uasyncio_start_server.py.exp b/tests/net_hosted/uasyncio_start_server.py.exp
@@ -0,0 +1,5 @@
+create server1
+create server2
+OSError
+sleep
+done

-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +create server1
 +create server2
 +OSError
 +sleep
 +done