add exception handling for forward handler

app/src/async_stream.py

@@ -1,6 +1,7 @@
 import logging
 import traceback
 from messages import hex_dump_memory
+from typing import Self
 
 logger = logging.getLogger('conn')
 
@@ -15,7 +16,7 @@ class AsyncStream():
         self.r_addr = ''
         self.l_addr = ''
 
-    async def server_loop(self, addr):
+    async def server_loop(self, addr: str) -> None:
         '''Loop for receiving messages from the inverter (server-side)'''
         logging.info(f'[{self.node_id}] Accept connection from {addr}')
         self.inc_counter('Inverter_Cnt')
@@ -34,7 +35,7 @@ class AsyncStream():
         except Exception:
             pass
 
-    async def client_loop(self, addr):
+    async def client_loop(self, addr: str) -> None:
         '''Loop for receiving messages from the TSUN cloud (client-side)'''
         clientStream = await self.remoteStream.loop()
         logging.info(f'[{self.node_id}] Client loop stopped for'
@@ -54,7 +55,8 @@ class AsyncStream():
             # than erase client connection
             self.remoteStream = None
 
-    async def loop(self):
+    async def loop(self) -> Self:
+        """Async loop handler for precessing all received messages"""
         self.r_addr = self.writer.get_extra_info('peername')
         self.l_addr = self.writer.get_extra_info('sockname')
 
@@ -86,14 +88,29 @@ class AsyncStream():
                     f"Exception for {self.addr}:\n"
                     f"{traceback.format_exc()}")
 
+    async def async_write(self, headline: str = 'Transmit to ') -> None:
+        """Async write handler to transmit the send_buffer"""
+        if self._send_buffer:
+            hex_dump_memory(logging.INFO, f'{headline}{self.addr}:',
+                            self._send_buffer, len(self._send_buffer))
+            self.writer.write(self._send_buffer)
+            await self.writer.drain()
+            self._send_buffer = bytearray(0)  # self._send_buffer[sent:]
+
     async def disc(self) -> None:
+        """Async disc handler for graceful disconnect"""
         if self.writer.is_closing():
             return
         logger.debug(f'AsyncStream.disc() l{self.l_addr} | r{self.r_addr}')
         self.writer.close()
         await self.writer.wait_closed()
 
-    def close(self):
+    def close(self) -> None:
+        """close handler for a no waiting disconnect
+
+           hint: must be called before releasing the connection instance
+        """
+        self.reader.feed_eof()          # abort awaited read
         if self.writer.is_closing():
             return
         logger.debug(f'AsyncStream.close() l{self.l_addr} | r{self.r_addr}')
@@ -103,6 +120,7 @@ class AsyncStream():
     Our private methods
     '''
     async def __async_read(self) -> None:
+        """Async read handler to read received data from TCP stream"""
         data = await self.reader.read(4096)
         if data:
             self._recv_buffer += data
@@ -110,16 +128,11 @@ class AsyncStream():
         else:
             raise RuntimeError("Peer closed.")
 
-    async def async_write(self, headline='Transmit to ') -> None:
-        if self._send_buffer:
-            hex_dump_memory(logging.INFO, f'{headline}{self.addr}:',
-                            self._send_buffer, len(self._send_buffer))
-            self.writer.write(self._send_buffer)
-            await self.writer.drain()
-            self._send_buffer = bytearray(0)  # self._send_buffer[sent:]
-
     async def __async_forward(self) -> None:
-        if self._forward_buffer:
+        """forward handler transmits data over the remote connection"""
+        if not self._forward_buffer:
+            return
+        try:
             if not self.remoteStream:
                 await self.async_create_remote()
                 if self.remoteStream:
@@ -136,6 +149,29 @@ class AsyncStream():
                 await self.remoteStream.writer.drain()
                 self._forward_buffer = bytearray(0)
 
+        except OSError as error:
+            if self.remoteStream:
+                rmt = self.remoteStream
+                self.remoteStream = None
+                logger.error(f'[{rmt.node_id}] Fwd: {error} for '
+                             f'l{rmt.l_addr} | r{rmt.r_addr}')
+                await rmt.disc()
+                rmt.close()
+
+        except RuntimeError as error:
+            if self.remoteStream:
+                rmt = self.remoteStream
+                self.remoteStream = None
+                logger.info(f"[{rmt.node_id}] Fwd: {error} for {rmt.l_addr}")
+                await rmt.disc()
+                rmt.close()
+
+        except Exception:
+            self.inc_counter('SW_Exception')
+            logger.error(
+                f"Fwd Exception for {self.addr}:\n"
+                f"{traceback.format_exc()}")
+
     def __del__(self):
         logger.debug(
             f"AsyncStream.__del__  l{self.l_addr} | r{self.r_addr}")