Catch `Exception` and not `BaseException` in the `Connection` (#2104)

* Add failing unittests for passing BaseException through

* Resolve failing unittest

* Remove redundant checks for asyncio.CancelledError

4 files changed, 121 insertions, 7 deletions

diff --git a/redis/asyncio/connection.py b/redis/asyncio/connection.py
index 16f33e2..a470b6f 100644
--- a/redis/asyncio/connection.py
+++ b/redis/asyncio/connection.py
@@ -502,8 +502,6 @@ class HiredisParser(BaseParser):
             # data was read from the socket and added to the buffer.
             # return True to indicate that data was read.
             return True
-        except asyncio.CancelledError:
-            raise
         except (socket.timeout, asyncio.TimeoutError):
             if raise_on_timeout:
                 raise TimeoutError("Timeout reading from socket") from None
@@ -721,7 +719,7 @@ class Connection:
                 lambda: self._connect(), lambda error: self.disconnect()
             )
         except asyncio.CancelledError:
-            raise
+            raise  # in 3.7 and earlier, this is an Exception, not BaseException
         except (socket.timeout, asyncio.TimeoutError):
             raise TimeoutError("Timeout connecting to server")
         except OSError as e:
@@ -916,7 +914,7 @@ class Connection:
             raise ConnectionError(
                 f"Error {err_no} while writing to socket. {errmsg}."
             ) from e
-        except BaseException:
+        except Exception:
             await self.disconnect()
             raise
 
@@ -958,7 +956,7 @@ class Connection:
             raise ConnectionError(
                 f"Error while reading from {self.host}:{self.port} : {e.args}"
             )
-        except BaseException:
+        except Exception:
             await self.disconnect()
             raise
 
diff --git a/redis/connection.py b/redis/connection.py
index 491df8e..2e33e31 100755
--- a/redis/connection.py
+++ b/redis/connection.py
@@ -766,7 +766,7 @@ class Connection:
                 errno = e.args[0]
                 errmsg = e.args[1]
             raise ConnectionError(f"Error {errno} while writing to socket. {errmsg}.")
-        except BaseException:
+        except Exception:
             self.disconnect()
             raise
 
@@ -804,7 +804,7 @@ class Connection:
         except OSError as e:
             self.disconnect()
             raise ConnectionError(f"Error while reading from {hosterr}" f" : {e.args}")
-        except BaseException:
+        except Exception:
             self.disconnect()
             raise
 
diff --git a/tests/test_asyncio/test_pubsub.py b/tests/test_asyncio/test_pubsub.py
index 2ff0c72..555cfdb 100644
--- a/tests/test_asyncio/test_pubsub.py
+++ b/tests/test_asyncio/test_pubsub.py
@@ -1,7 +1,9 @@
 import asyncio
 import functools
 import socket
+import sys
 from typing import Optional
+from unittest.mock import patch
 
 import async_timeout
 import pytest
@@ -914,3 +916,75 @@ class TestPubSubAutoReconnect:
                     return True
         except asyncio.TimeoutError:
             return False
+
+
+@pytest.mark.onlynoncluster
+class TestBaseException:
+    @pytest.mark.skipif(
+        sys.version_info < (3, 8), reason="requires python 3.8 or higher"
+    )
+    async def test_outer_timeout(self, r: redis.Redis):
+        """
+        Using asyncio_timeout manually outside the inner method timeouts works.
+        This works on Python versions 3.8 and greater, at which time asyncio.
+        CancelledError became a BaseException instead of an Exception before.
+        """
+        pubsub = r.pubsub()
+        await pubsub.subscribe("foo")
+        assert pubsub.connection.is_connected
+
+        async def get_msg_or_timeout(timeout=0.1):
+            async with async_timeout.timeout(timeout):
+                # blocking method to return messages
+                while True:
+                    response = await pubsub.parse_response(block=True)
+                    message = await pubsub.handle_message(
+                        response, ignore_subscribe_messages=False
+                    )
+                    if message is not None:
+                        return message
+
+        # get subscribe message
+        msg = await get_msg_or_timeout(10)
+        assert msg is not None
+        # timeout waiting for another message which never arrives
+        assert pubsub.connection.is_connected
+        with pytest.raises(asyncio.TimeoutError):
+            await get_msg_or_timeout()
+        # the timeout on the read should not cause disconnect
+        assert pubsub.connection.is_connected
+
+    async def test_base_exception(self, r: redis.Redis):
+        """
+        Manually trigger a BaseException inside the parser's .read_response method
+        and verify that it isn't caught
+        """
+        pubsub = r.pubsub()
+        await pubsub.subscribe("foo")
+        assert pubsub.connection.is_connected
+
+        async def get_msg():
+            # blocking method to return messages
+            while True:
+                response = await pubsub.parse_response(block=True)
+                message = await pubsub.handle_message(
+                    response, ignore_subscribe_messages=False
+                )
+                if message is not None:
+                    return message
+
+        # get subscribe message
+        msg = await get_msg()
+        assert msg is not None
+        # timeout waiting for another message which never arrives
+        assert pubsub.connection.is_connected
+        with patch("redis.asyncio.connection.PythonParser.read_response") as mock1:
+            mock1.side_effect = BaseException("boom")
+            with patch("redis.asyncio.connection.HiredisParser.read_response") as mock2:
+                mock2.side_effect = BaseException("boom")
+
+                with pytest.raises(BaseException):
+                    await get_msg()
+
+        # the timeout on the read should not cause disconnect
+        assert pubsub.connection.is_connected
diff --git a/tests/test_pubsub.py b/tests/test_pubsub.py
index 26df598..5d86934 100644
--- a/tests/test_pubsub.py
+++ b/tests/test_pubsub.py
@@ -735,3 +735,45 @@ class TestPubSubAutoReconnect:
         for message in self.pubsub.listen():
             self.messages.put(message)
             return True
+
+
+@pytest.mark.onlynoncluster
+class TestBaseException:
+    def test_base_exception(self, r: redis.Redis):
+        """
+        Manually trigger a BaseException inside the parser's .read_response method
+        and verify that it isn't caught
+        """
+        pubsub = r.pubsub()
+        pubsub.subscribe("foo")
+
+        def is_connected():
+            return pubsub.connection._sock is not None
+
+        assert is_connected()
+
+        def get_msg():
+            # blocking method to return messages
+            while True:
+                response = pubsub.parse_response(block=True)
+                message = pubsub.handle_message(
+                    response, ignore_subscribe_messages=False
+                )
+                if message is not None:
+                    return message
+
+        # get subscribe message
+        msg = get_msg()
+        assert msg is not None
+        # timeout waiting for another message which never arrives
+        assert is_connected()
+        with patch("redis.connection.PythonParser.read_response") as mock1:
+            mock1.side_effect = BaseException("boom")
+            with patch("redis.connection.HiredisParser.read_response") as mock2:
+                mock2.side_effect = BaseException("boom")
+
+                with pytest.raises(BaseException):
+                    get_msg()
+
+        # the timeout on the read should not cause disconnect
+        assert is_connected()