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[MQTT] Implemented remaining length decoding

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This commit is contained in:
jgromes 2020-07-05 09:59:40 +02:00
parent eeb70e24bd
commit 0dd3e347a0
2 changed files with 8 additions and 6 deletions
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12
src/protocols/MQTT/MQTT.cpp
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@ -411,10 +411,11 @@ int16_t MQTTClient::check(void (*func)(const char*, const char*)) {
_tl->receive(dataIn, numBytes);
if(dataIn[0] == MQTT_PUBLISH << 4) {
// TODO: properly decode remaining length
uint8_t remainingLength = dataIn[1];
uint8_t remLenFieldLen = 0;
uint32_t remainingLength = decodeLength(dataIn + 1, remLenFieldLen);
// get the topic
size_t topicLength = dataIn[3] | dataIn[2] << 8;
size_t topicLength = dataIn[remLenFieldLen + 2] | dataIn[remLenFieldLen + 1] << 8;
char* topic = new char[topicLength + 1];
memcpy(topic, dataIn + 4, topicLength);
topic[topicLength] = 0x00;
@ -422,7 +423,7 @@ int16_t MQTTClient::check(void (*func)(const char*, const char*)) {
// get the message
size_t messageLength = remainingLength - topicLength - 2;
char* message = new char[messageLength + 1];
memcpy(message, dataIn + 4 + topicLength, messageLength);
memcpy(message, dataIn + remLenFieldLen + 3 + topicLength, messageLength);
message[messageLength] = 0x00;
// execute the callback function provided by user
@ -452,7 +453,7 @@ size_t MQTTClient::encodeLength(uint32_t len, uint8_t* encoded) {
return(i);
}
uint32_t MQTTClient::decodeLength(uint8_t* encoded) {
uint32_t MQTTClient::decodeLength(uint8_t* encoded, uint8_t& numBytes) {
// algorithm to decode packet length as per MQTT specification 3.1.1
uint32_t mult = 1;
uint32_t len = 0;
@ -464,7 +465,8 @@ uint32_t MQTTClient::decodeLength(uint8_t* encoded) {
// malformed remaining length
return(0);
}
} while((encoded[i] & 128) != 0);
} while((encoded[i++] & 128) != 0);
numBytes = i;
return len;
}

2
src/protocols/MQTT/MQTT.h
View file

@ -139,7 +139,7 @@ class MQTTClient {
uint16_t _packetId;
static size_t encodeLength(uint32_t len, uint8_t* encoded);
static uint32_t decodeLength(uint8_t* encoded);
static uint32_t decodeLength(uint8_t* encoded, uint8_t& numBytes);
};
#endif