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Check for empty topic filters in subscribes #139

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merged 1 commit into from
Dec 11, 2020
Merged

Check for empty topic filters in subscribes #139

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34 changes: 16 additions & 18 deletions source/core_mqtt_serializer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -201,7 +201,7 @@ static bool calculatePublishPacketSize( const MQTTPublishInfo_t * pPublishInfo,
* @param[in] subscriptionType #MQTT_SUBSCRIBE or #MQTT_UNSUBSCRIBE.
*
* #MQTTBadParameter if the packet would exceed the size allowed by the
* MQTT spec; #MQTTSuccess otherwise.
* MQTT spec or a subscription is empty; #MQTTSuccess otherwise.
*/
static MQTTStatus_t calculateSubscriptionPacketSize( const MQTTSubscribeInfo_t * pSubscriptionList,
size_t subscriptionCount,
Expand Down Expand Up @@ -1032,6 +1032,17 @@ static MQTTStatus_t calculateSubscriptionPacketSize( const MQTTSubscribeInfo_t *
{
packetSize += 1U;
}

/* Validate each topic filter. */
if( ( pSubscriptionList[ i ].topicFilterLength == 0U ) ||
( pSubscriptionList[ i ].pTopicFilter == NULL ) )
{
status = MQTTBadParameter;
LogError( ( "Subscription #%lu in %sSUBSCRIBE packet cannot be empty.",
( unsigned long ) i,
( subscriptionType == MQTT_SUBSCRIBE ) ? "" : "UN" ) );
/* It is not necessary to break as an error status has already been set. */
}
}

/* At this point, the "Remaining length" has been calculated. Return error
Expand All @@ -1045,7 +1056,8 @@ static MQTTStatus_t calculateSubscriptionPacketSize( const MQTTSubscribeInfo_t *
MQTT_MAX_REMAINING_LENGTH ) );
status = MQTTBadParameter;
}
else

if( status == MQTTSuccess )
{
*pRemainingLength = packetSize;

Expand Down Expand Up @@ -1669,19 +1681,12 @@ MQTTStatus_t MQTT_GetSubscribePacketSize( const MQTTSubscribeInfo_t * pSubscript
}
else
{
/* Calculate the MQTT UNSUBSCRIBE packet size. */
/* Calculate the MQTT SUBSCRIBE packet size. */
status = calculateSubscriptionPacketSize( pSubscriptionList,
subscriptionCount,
pRemainingLength,
pPacketSize,
MQTT_SUBSCRIBE );

if( status == MQTTBadParameter )
{
LogError( ( "SUBSCRIBE packet remaining length exceeds %lu, which is the "
"maximum size allowed by MQTT 3.1.1.",
MQTT_MAX_REMAINING_LENGTH ) );
}
}

return status;
Expand Down Expand Up @@ -1768,19 +1773,12 @@ MQTTStatus_t MQTT_GetUnsubscribePacketSize( const MQTTSubscribeInfo_t * pSubscri
}
else
{
/* Calculate the MQTT SUBSCRIBE packet size. */
/* Calculate the MQTT UNSUBSCRIBE packet size. */
status = calculateSubscriptionPacketSize( pSubscriptionList,
subscriptionCount,
pRemainingLength,
pPacketSize,
MQTT_UNSUBSCRIBE );

if( status == MQTTBadParameter )
{
LogError( ( "UNSUBSCRIBE packet remaining length exceeds %lu, which is the "
"maximum size allowed by MQTT 3.1.1.",
MQTT_MAX_REMAINING_LENGTH ) );
}
}

return status;
Expand Down
44 changes: 42 additions & 2 deletions test/unit-test/core_mqtt_serializer_utest.c
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Original file line number Diff line number Diff line change
Expand Up @@ -656,7 +656,7 @@ void test_MQTT_SerializeConnect( void )
void test_MQTT_GetSubscribePacketSize( void )
{
MQTTSubscribeInfo_t subscriptionList;
size_t subscriptionCount = 0;
size_t subscriptionCount = 1;
size_t remainingLength = 0;
size_t packetSize = 0;
MQTTStatus_t status = MQTTSuccess;
Expand Down Expand Up @@ -693,6 +693,22 @@ void test_MQTT_GetSubscribePacketSize( void )
&packetSize );
TEST_ASSERT_EQUAL_INT( MQTTBadParameter, status );

/* Zero length topic filter. */
subscriptionCount = 1;
status = MQTT_GetSubscribePacketSize( &subscriptionList,
subscriptionCount,
&remainingLength,
&packetSize );
TEST_ASSERT_EQUAL_INT( MQTTBadParameter, status );

/* NULL topic filter, nonzero length. */
subscriptionList.topicFilterLength = 1;
status = MQTT_GetSubscribePacketSize( &subscriptionList,
subscriptionCount,
&remainingLength,
&packetSize );
TEST_ASSERT_EQUAL_INT( MQTTBadParameter, status );

/* Verify packet size cannot exceed limit. Note the max remaining length of
* an MQTT packet is 2^28-1 = 268435455, or 256MiB. Since the only way to increase
* the subscribe packet size is with the topic filters of the subscriptions
Expand All @@ -701,6 +717,10 @@ void test_MQTT_GetSubscribePacketSize( void )
for( i = 0; i < 4096; i++ )
{
fourThousandSubscriptions[ i ].topicFilterLength = UINT16_MAX;

/* We need to set this to avoid an early bad parameter, however we do
* not need a 65535 byte buffer as the packet will not be serialized. */
fourThousandSubscriptions[ i ].pTopicFilter = "";
}

subscriptionCount = sizeof( fourThousandSubscriptions ) / sizeof( fourThousandSubscriptions[ 0 ] );
Expand Down Expand Up @@ -730,7 +750,7 @@ void test_MQTT_GetSubscribePacketSize( void )
void test_MQTT_GetUnsubscribePacketSize( void )
{
MQTTSubscribeInfo_t subscriptionList;
size_t subscriptionCount = 0;
size_t subscriptionCount = 1;
size_t remainingLength = 0;
size_t packetSize = 0;
MQTTStatus_t status = MQTTSuccess;
Expand Down Expand Up @@ -767,6 +787,22 @@ void test_MQTT_GetUnsubscribePacketSize( void )
&packetSize );
TEST_ASSERT_EQUAL_INT( MQTTBadParameter, status );

/* Zero length topic filter. */
subscriptionCount = 1;
status = MQTT_GetUnsubscribePacketSize( &subscriptionList,
subscriptionCount,
&remainingLength,
&packetSize );
TEST_ASSERT_EQUAL_INT( MQTTBadParameter, status );

/* NULL topic filter, nonzero length. */
subscriptionList.topicFilterLength = 1;
status = MQTT_GetUnsubscribePacketSize( &subscriptionList,
subscriptionCount,
&remainingLength,
&packetSize );
TEST_ASSERT_EQUAL_INT( MQTTBadParameter, status );

/* Verify packet size cannot exceed limit. Note the max remaining length of
* an MQTT packet is 2^28-1 = 268435455, or 256MiB. Since the only way to increase
* the subscribe packet size is with the topic filters of the subscriptions
Expand All @@ -775,6 +811,10 @@ void test_MQTT_GetUnsubscribePacketSize( void )
for( i = 0; i < 4096; i++ )
{
fourThousandSubscriptions[ i ].topicFilterLength = UINT16_MAX;

/* We need to set this to avoid an early bad parameter, however we do
* not need a 65535 byte buffer as the packet will not be serialized. */
fourThousandSubscriptions[ i ].pTopicFilter = "";
}

subscriptionCount = sizeof( fourThousandSubscriptions ) / sizeof( fourThousandSubscriptions[ 0 ] );
Expand Down