Merge pull request adafruit#133 from vladak/exact_recv_is_not

make sure to read the whole buffer in _sock_exact_recv()

Author: brentru

adafruit_minimqtt/adafruit_minimqtt.py

@@ -316,35 +316,6 @@ def __enter__(self):
     def __exit__(self, exception_type, exception_value, traceback):
         self.deinit()
 
-    def _sock_exact_recv(self, bufsize):
-        """Reads _exact_ number of bytes from the connected socket. Will only return
-        string with the exact number of bytes requested.
-
-        The semantics of native socket receive is that it returns no more than the
-        specified number of bytes (i.e. max size). However, it makes no guarantees in
-        terms of the minimum size of the buffer, which could be 1 byte. This is a
-        wrapper for socket recv() to ensure that no less than the expected number of
-        bytes is returned or trigger a timeout exception.
-
-        :param int bufsize: number of bytes to receive
-        """
-        stamp = time.monotonic()
-        rc = self._sock.recv(bufsize)
-        to_read = bufsize - len(rc)
-        assert to_read >= 0
-        read_timeout = self.keep_alive
-        while to_read > 0:
-            recv = self._sock.recv(to_read)
-            to_read -= len(recv)
-            rc += recv
-            if time.monotonic() - stamp > read_timeout:
-                raise MMQTTException(
-                    "Unable to receive {} bytes within {} seconds.".format(
-                        to_read, read_timeout
-                    )
-                )
-        return rc
-
     def deinit(self):
         """De-initializes the MQTT client and disconnects from the mqtt broker."""
         self.disconnect()
@@ -988,15 +959,28 @@ def _sock_exact_recv(self, bufsize):
         bytes is returned or trigger a timeout exception.
 
         :param int bufsize: number of bytes to receive
-
+        :return: byte array
         """
+        stamp = time.monotonic()
         if not self._backwards_compatible_sock:
             # CPython/Socketpool Impl.
             rc = bytearray(bufsize)
-            self._sock.recv_into(rc, bufsize)
-        else:  # ESP32SPI Impl.
-            stamp = time.monotonic()
+            mv = memoryview(rc)
+            recv_len = self._sock.recv_into(rc, bufsize)
+            to_read = bufsize - recv_len
+            if to_read < 0:
+                raise MMQTTException(f"negative number of bytes to read: {to_read}")
             read_timeout = self.keep_alive
+            mv = mv[recv_len:]
+            while to_read > 0:
+                recv_len = self._sock.recv_into(mv, to_read)
+                to_read -= recv_len
+                mv = mv[recv_len:]
+                if time.monotonic() - stamp > read_timeout:
+                    raise MMQTTException(
+                        f"Unable to receive {to_read} bytes within {read_timeout} seconds."
+                    )
+        else:  # ESP32SPI Impl.
             # This will timeout with socket timeout (not keepalive timeout)
             rc = self._sock.recv(bufsize)
             if not rc:
@@ -1015,9 +999,7 @@ def _sock_exact_recv(self, bufsize):
                 rc += recv
                 if time.monotonic() - stamp > read_timeout:
                     raise MMQTTException(
-                        "Unable to receive {} bytes within {} seconds.".format(
-                            to_read, read_timeout
-                        )
+                        f"Unable to receive {to_read} bytes within {read_timeout} seconds."
                     )
         return rc