fix AbstractTransport repr socket error (#361)

If AbstractTransport's self.sock is disconnected, then
self.sock.getpeername() will raise an error in __repr__, which shows up
in backtraces for other upstream errors.

Fix this by catching socket.error in __repr__ and putting the error info
in to the returned repr string.

Fixes #361

amqp/transport.py

@@ -116,7 +116,10 @@ def __init__(self, host, connect_timeout=None,
     def __repr__(self):
         if self.sock:
             src = f'{self.sock.getsockname()[0]}:{self.sock.getsockname()[1]}'
-            dst = f'{self.sock.getpeername()[0]}:{self.sock.getpeername()[1]}'
+            try:
+                dst = f'{self.sock.getpeername()[0]}:{self.sock.getpeername()[1]}'
+            except (socket.error) as e:
+                dst = f'ERROR: {e}'
             return f'<{type(self).__name__}: {src} -> {dst} at {id(self):#x}>'
         else:
             return f'<{type(self).__name__}: (disconnected) at {id(self):#x}>'

t/unit/test_transport.py

@@ -59,7 +59,10 @@ def getsockname(self):
         return ('127.0.0.1', 1234)
 
     def getpeername(self):
-        return ('1.2.3.4', 5671)
+        if self.connected:
+            return ('1.2.3.4', 5671)
+        else:
+            raise socket.error
 
 
 TCP_KEEPIDLE = 4
@@ -237,6 +240,17 @@ def test_set_sockopt_opts_timeout(self):
         assert expected_sndtimeo == self.socket.getsockopt(socket.SOL_TCP,
                                                            socket.SO_SNDTIMEO)
 
+    def test_transport_repr_issue_361(self):
+        "Regression test for https://github.com/celery/py-amqp/issues/361"
+        self.t = transport.Transport(self.host)
+        self.t.sock = MockSocket()
+        self.t.sock.connect(None)
+        assert '127.0.0.1:1234 -> 1.2.3.4:5671' in repr(self.t)
+
+        self.t.sock.connected = False
+        self.t.sock.close()
+        assert '127.0.0.1:1234 -> ERROR:' in repr(self.t)
+
 
 class test_AbstractTransport:
     class Transport(transport._AbstractTransport):