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make sure to read the whole buffer in _sock_exact_recv() #133

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Merged
merged 6 commits into from
Jan 12, 2023
Merged

make sure to read the whole buffer in _sock_exact_recv() #133

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d60ab23
remove duplicate _sock_exact_recv() definition
vladak Dec 5, 2022
c334c81
finish partial reads in CPython
vladak Dec 5, 2022
f0fd465
rename variable for better readability
vladak Dec 6, 2022
c0a902a
use f-strings for the exceptions
vladak Dec 7, 2022
8f51710
use MMQTTException instead of assert for the negative read length
vladak Jan 12, 2023
be9c198
try different format
vladak Jan 12, 2023
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54 changes: 18 additions & 36 deletions adafruit_minimqtt/adafruit_minimqtt.py
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Original file line number Diff line number Diff line change
Expand Up @@ -313,35 +313,6 @@ 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()
Expand Down Expand Up @@ -985,15 +956,28 @@ 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:
Expand All @@ -1012,9 +996,7 @@ 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

Expand Down