Merge pull request #193 from xdylanm/send_rcv_long_packets

Support publishing and receiving large messages.

Author: brentru

Adafruit_MQTT.cpp

@@ -96,6 +96,22 @@ static uint8_t *stringprint(uint8_t *p, const char *s, uint16_t maxlen = 0) {
   return p + len;
 }
 
+// packetAdditionalLen is a helper function used to figure out
+// how bigger the payload needs to be in order to account for
+// its variable length field. As per
+// http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Table_2.4_Size
+// See also readFullPacket
+static uint16_t packetAdditionalLen(uint32_t currLen) {
+  /* Increase length field based on current length */
+  if (currLen < 128) // 7-bits
+    return 0;
+  if (currLen < 16384) // 14-bits
+    return 1;
+  if (currLen < 2097152) // 21-bits
+    return 2;
+  return 3;
+}
+
 // Adafruit_MQTT Definition ////////////////////////////////////////////////////
 
 Adafruit_MQTT::Adafruit_MQTT(const char *server, uint16_t port, const char *cid,
@@ -233,7 +249,7 @@ uint16_t Adafruit_MQTT::readFullPacket(uint8_t *buffer, uint16_t maxsize,
   // will read a packet and Do The Right Thing with length
   uint8_t *pbuff = buffer;
 
-  uint8_t rlen;
+  uint16_t rlen;
 
   // read the packet type:
   rlen = readPacket(pbuff, 1, timeout);
@@ -267,7 +283,8 @@ uint16_t Adafruit_MQTT::readFullPacket(uint8_t *buffer, uint16_t maxsize,
   DEBUG_PRINT(F("Packet Length:\t"));
   DEBUG_PRINTLN(value);
 
-  if (value > (maxsize - (pbuff - buffer) - 1)) {
+  // maxsize is limited to 65536 by 16-bit unsigned
+  if (value > uint32_t(maxsize - (pbuff - buffer) - 1)) {
     DEBUG_PRINTLN(F("Packet too big for buffer"));
     rlen = readPacket(pbuff, (maxsize - (pbuff - buffer) - 1), timeout);
   } else {
@@ -492,7 +509,9 @@ Adafruit_MQTT_Subscribe *Adafruit_MQTT::handleSubscriptionPacket(uint16_t len) {
   }
 
   // Parse out length of packet.
-  topiclen = buffer[3];
+  uint16_t const topicoffset = packetAdditionalLen(len);
+  uint16_t const topicstart = topicoffset + 4;
+  topiclen = buffer[3 + topicoffset];
   DEBUG_PRINT(F("Looking for subscription len "));
   DEBUG_PRINTLN(topiclen);
 
@@ -505,8 +524,8 @@ Adafruit_MQTT_Subscribe *Adafruit_MQTT::handleSubscriptionPacket(uint16_t len) {
         continue;
       // Stop if the subscription topic matches the received topic. Be careful
       // to make comparison case insensitive.
-      if (strncasecmp((char *)buffer + 4, subscriptions[i]->topic, topiclen) ==
-          0) {
+      if (strncasecmp((char *)buffer + topicstart, subscriptions[i]->topic,
+                      topiclen) == 0) {
         DEBUG_PRINT(F("Found sub #"));
         DEBUG_PRINTLN(i);
         break;
@@ -521,21 +540,21 @@ Adafruit_MQTT_Subscribe *Adafruit_MQTT::handleSubscriptionPacket(uint16_t len) {
   // Check if it is QoS 1, TODO: we dont support QoS 2
   if ((buffer[0] & 0x6) == 0x2) {
     packet_id_len = 2;
-    packetid = buffer[topiclen + 4];
+    packetid = buffer[topiclen + topicstart];
     packetid <<= 8;
-    packetid |= buffer[topiclen + 5];
+    packetid |= buffer[topiclen + topicstart + 1];
   }
 
   // zero out the old data
   memset(subscriptions[i]->lastread, 0, SUBSCRIPTIONDATALEN);
 
-  datalen = len - topiclen - packet_id_len - 4;
+  datalen = len - topiclen - packet_id_len - topicstart;
   if (datalen > SUBSCRIPTIONDATALEN) {
     datalen = SUBSCRIPTIONDATALEN - 1; // cut it off
   }
   // extract out just the data, into the subscription object itself
-  memmove(subscriptions[i]->lastread, buffer + 4 + topiclen + packet_id_len,
-          datalen);
+  memmove(subscriptions[i]->lastread,
+          buffer + topicstart + topiclen + packet_id_len, datalen);
   subscriptions[i]->datalen = datalen;
   DEBUG_PRINT(F("Data len: "));
   DEBUG_PRINTLN(datalen);
@@ -669,21 +688,6 @@ uint8_t Adafruit_MQTT::connectPacket(uint8_t *packet) {
   return len;
 }
 
-// packetAdditionalLen is a helper function used to figure out
-// how bigger the payload needs to be in order to account for
-// its variable length field. As per
-// http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Table_2.4_Size
-static uint16_t packetAdditionalLen(uint16_t currLen) {
-  /* Increase length field based on current length */
-  if (currLen < 128)
-    return 0;
-  if (currLen < 16384)
-    return 1;
-  if (currLen < 2097151)
-    return 2;
-  return 3;
-}
-
 // as per
 // http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc398718040
 uint16_t Adafruit_MQTT::publishPacket(uint8_t *packet, const char *topic,

Adafruit_MQTT_Client.cpp

@@ -83,17 +83,18 @@ uint16_t Adafruit_MQTT_Client::readPacket(uint8_t *buffer, uint16_t maxlen,
 
 bool Adafruit_MQTT_Client::sendPacket(uint8_t *buffer, uint16_t len) {
   uint16_t ret = 0;
-
+  uint16_t offset = 0;
   while (len > 0) {
     if (client->connected()) {
       // send 250 bytes at most at a time, can adjust this later based on Client
 
       uint16_t sendlen = len > 250 ? 250 : len;
       // Serial.print("Sending: "); Serial.println(sendlen);
-      ret = client->write(buffer, sendlen);
+      ret = client->write(buffer + offset, sendlen);
       DEBUG_PRINT(F("Client sendPacket returned: "));
       DEBUG_PRINTLN(ret);
       len -= ret;
+      offset += ret;
 
       if (ret != sendlen) {
         DEBUG_PRINTLN("Failed to send packet.");

library.properties

@@ -1,5 +1,5 @@
 name=Adafruit MQTT Library
-version=2.2.0
+version=2.3.0
 author=Adafruit
 maintainer=Adafruit <info@adafruit.com>
 sentence=MQTT library that supports the FONA, ESP8266, Yun, and generic Arduino Client hardware.