Merge branch 'master' into esp8266_example_fixes

.gitignore

@@ -1 +1,5 @@
 tests/bin
+.pioenvs
+.piolibdeps
+.clang_complete
+.gcc-flags.json

CHANGES.txt

@@ -1,8 +1,16 @@
+2.7
+   * Fix remaining-length handling to prevent buffer overrun
+   * Add large-payload API - beginPublish/write/publish/endPublish
+   * Add yield call to improve reliability on ESP
+   * Add Clean Session flag to connect options
+   * Add ESP32 support for functional callback signature
+   * Various other fixes
+
 2.4
    * Add MQTT_SOCKET_TIMEOUT to prevent it blocking indefinitely
      whilst waiting for inbound data
    * Fixed return code when publishing >256 bytes
-   
+
 2.3
    * Add publish(topic,payload,retained) function
 

README.md

@@ -8,13 +8,13 @@ a server that supports MQTT.
 The library comes with a number of example sketches. See File > Examples > PubSubClient
 within the Arduino application.
 
-Full API documentation is available here: http://pubsubclient.knolleary.net
+Full API documentation is available here: https://pubsubclient.knolleary.net
 
 ## Limitations
 
  - It can only publish QoS 0 messages. It can subscribe at QoS 0 or QoS 1.
  - The maximum message size, including header, is **128 bytes** by default. This
-   is configurable via `MQTT_MAX_PACKET_SIZE` in `PubSubClient.h`.
+   is configurable via `MQTT_MAX_PACKET_SIZE` in `PubSubClient.h`.  Longer messages can also be sent with the `publish_P()` method.
  - The keepalive interval is set to 15 seconds by default. This is configurable
    via `MQTT_KEEPALIVE` in `PubSubClient.h`.
  - The client uses MQTT 3.1.1 by default. It can be changed to use MQTT 3.1 by
@@ -37,6 +37,7 @@ boards and shields, including:
  - TI CC3000 WiFi - [library](https://github.com/sparkfun/SFE_CC3000_Library)
  - Intel Galileo/Edison
  - ESP8266
+ - ESP32
 
 The library cannot currently be used with hardware based on the ENC28J60 chip –
 such as the Nanode or the Nuelectronics Ethernet Shield. For those, there is an

examples/mqtt_esp8266/mqtt_esp8266.ino

@@ -1,26 +1,21 @@
 /*
  Basic ESP8266 MQTT example
-
  This sketch demonstrates the capabilities of the pubsub library in combination
  with the ESP8266 board/library.
-
  It connects to an MQTT server then:
   - publishes "hello world" to the topic "outTopic" every two seconds
   - subscribes to the topic "inTopic", printing out any messages
     it receives. NB - it assumes the received payloads are strings not binary
   - If the first character of the topic "inTopic" is an 1, switch ON the ESP Led,
     else switch it off
-
  It will reconnect to the server if the connection is lost using a blocking
  reconnect function. See the 'mqtt_reconnect_nonblocking' example for how to
  achieve the same result without blocking the main loop.
-
  To install the ESP8266 board, (using Arduino 1.6.4+):
   - Add the following 3rd party board manager under "File -> Preferences -> Additional Boards Manager URLs":
        http://arduino.esp8266.com/stable/package_esp8266com_index.json
   - Open the "Tools -> Board -> Board Manager" and click install for the ESP8266"
   - Select your ESP8266 in "Tools -> Board"
-
 */
 
 #include <ESP8266WiFi.h>
@@ -75,7 +70,7 @@ void callback(char* topic, byte* payload, unsigned int length) {
   if ((char)payload[0] == '1') {
     digitalWrite(BUILTIN_LED, LOW);   // Turn the LED on (Note that LOW is the voltage level
     // but actually the LED is on; this is because
-    // it is acive low on the ESP-01)
+    // it is active low on the ESP-01)
   } else {
     digitalWrite(BUILTIN_LED, HIGH);  // Turn the LED off by making the voltage HIGH
   }

examples/mqtt_large_message/mqtt_large_message.ino

@@ -0,0 +1,179 @@
+/*
+ Long message ESP8266 MQTT example
+
+ This sketch demonstrates sending arbitrarily large messages in combination
+ with the ESP8266 board/library.
+
+ It connects to an MQTT server then:
+  - publishes "hello world" to the topic "outTopic"
+  - subscribes to the topic "greenBottles/#", printing out any messages
+    it receives. NB - it assumes the received payloads are strings not binary
+  - If the sub-topic is a number, it publishes a "greenBottles/lyrics" message
+    with a payload consisting of the lyrics to "10 green bottles", replacing
+    10 with the number given in the sub-topic.
+
+ It will reconnect to the server if the connection is lost using a blocking
+ reconnect function. See the 'mqtt_reconnect_nonblocking' example for how to
+ achieve the same result without blocking the main loop.
+
+ To install the ESP8266 board, (using Arduino 1.6.4+):
+  - Add the following 3rd party board manager under "File -> Preferences -> Additional Boards Manager URLs":
+       http://arduino.esp8266.com/stable/package_esp8266com_index.json
+  - Open the "Tools -> Board -> Board Manager" and click install for the ESP8266"
+  - Select your ESP8266 in "Tools -> Board"
+
+*/
+
+#include <ESP8266WiFi.h>
+#include <PubSubClient.h>
+
+// Update these with values suitable for your network.
+
+const char* ssid = "........";
+const char* password = "........";
+const char* mqtt_server = "broker.mqtt-dashboard.com";
+
+WiFiClient espClient;
+PubSubClient client(espClient);
+long lastMsg = 0;
+char msg[50];
+int value = 0;
+
+void setup_wifi() {
+
+  delay(10);
+  // We start by connecting to a WiFi network
+  Serial.println();
+  Serial.print("Connecting to ");
+  Serial.println(ssid);
+
+  WiFi.begin(ssid, password);
+
+  while (WiFi.status() != WL_CONNECTED) {
+    delay(500);
+    Serial.print(".");
+  }
+
+  randomSeed(micros());
+
+  Serial.println("");
+  Serial.println("WiFi connected");
+  Serial.println("IP address: ");
+  Serial.println(WiFi.localIP());
+}
+
+void callback(char* topic, byte* payload, unsigned int length) {
+  Serial.print("Message arrived [");
+  Serial.print(topic);
+  Serial.print("] ");
+  for (int i = 0; i < length; i++) {
+    Serial.print((char)payload[i]);
+  }
+  Serial.println();
+
+  // Find out how many bottles we should generate lyrics for
+  String topicStr(topic);
+  int bottleCount = 0; // assume no bottles unless we correctly parse a value from the topic
+  if (topicStr.indexOf('/') >= 0) {
+    // The topic includes a '/', we'll try to read the number of bottles from just after that
+    topicStr.remove(0, topicStr.indexOf('/')+1);
+    // Now see if there's a number of bottles after the '/'
+    bottleCount = topicStr.toInt();
+  }
+
+  if (bottleCount > 0) {
+    // Work out how big our resulting message will be
+    int msgLen = 0;
+    for (int i = bottleCount; i > 0; i--) {
+      String numBottles(i);
+      msgLen += 2*numBottles.length();
+      if (i == 1) {
+        msgLen += 2*String(" green bottle, standing on the wall\n").length();
+      } else {
+        msgLen += 2*String(" green bottles, standing on the wall\n").length();
+      }
+      msgLen += String("And if one green bottle should accidentally fall\nThere'll be ").length();
+      switch (i) {
+      case 1:
+        msgLen += String("no green bottles, standing on the wall\n\n").length();
+        break;
+      case 2:
+        msgLen += String("1 green bottle, standing on the wall\n\n").length();
+        break;
+      default:
+        numBottles = i-1;
+        msgLen += numBottles.length();
+        msgLen += String(" green bottles, standing on the wall\n\n").length();
+        break;
+      };
+    }
+  
+    // Now we can start to publish the message
+    client.beginPublish("greenBottles/lyrics", msgLen, false);
+    for (int i = bottleCount; i > 0; i--) {
+      for (int j = 0; j < 2; j++) {
+        client.print(i);
+        if (i == 1) {
+          client.print(" green bottle, standing on the wall\n");
+        } else {
+          client.print(" green bottles, standing on the wall\n");
+        }
+      }
+      client.print("And if one green bottle should accidentally fall\nThere'll be ");
+      switch (i) {
+      case 1:
+        client.print("no green bottles, standing on the wall\n\n");
+        break;
+      case 2:
+        client.print("1 green bottle, standing on the wall\n\n");
+        break;
+      default:
+        client.print(i-1);
+        client.print(" green bottles, standing on the wall\n\n");
+        break;
+      };
+    }
+    // Now we're done!
+    client.endPublish();
+  }
+}
+
+void reconnect() {
+  // Loop until we're reconnected
+  while (!client.connected()) {
+    Serial.print("Attempting MQTT connection...");
+    // Create a random client ID
+    String clientId = "ESP8266Client-";
+    clientId += String(random(0xffff), HEX);
+    // Attempt to connect
+    if (client.connect(clientId.c_str())) {
+      Serial.println("connected");
+      // Once connected, publish an announcement...
+      client.publish("outTopic", "hello world");
+      // ... and resubscribe
+      client.subscribe("greenBottles/#");
+    } else {
+      Serial.print("failed, rc=");
+      Serial.print(client.state());
+      Serial.println(" try again in 5 seconds");
+      // Wait 5 seconds before retrying
+      delay(5000);
+    }
+  }
+}
+
+void setup() {
+  pinMode(BUILTIN_LED, OUTPUT);     // Initialize the BUILTIN_LED pin as an output
+  Serial.begin(115200);
+  setup_wifi();
+  client.setServer(mqtt_server, 1883);
+  client.setCallback(callback);
+}
+
+void loop() {
+
+  if (!client.connected()) {
+    reconnect();
+  }
+  client.loop();
+}

keywords.txt

@@ -16,6 +16,9 @@ connect 	KEYWORD2
 disconnect 	KEYWORD2
 publish 	KEYWORD2
 publish_P 	KEYWORD2
+beginPublish 	KEYWORD2
+endPublish 	KEYWORD2
+write	 	KEYWORD2
 subscribe 	KEYWORD2
 unsubscribe 	KEYWORD2
 loop 	KEYWORD2

library.json

@@ -6,7 +6,7 @@
         "type": "git",
         "url": "https://github.com/knolleary/pubsubclient.git"
     },
-    "version": "2.6",
+    "version": "2.7",
     "exclude": "tests",
     "examples": "examples/*/*.ino",
     "frameworks": "arduino",

library.properties

@@ -1,5 +1,5 @@
 name=PubSubClient
-version=2.6
+version=2.7
 author=Nick O'Leary <nick.oleary@gmail.com>
 maintainer=Nick O'Leary <nick.oleary@gmail.com>
 sentence=A client library for MQTT messaging.

src/PubSubClient.cpp

@@ -1,4 +1,5 @@
 /*
+
   PubSubClient.cpp - A simple client for MQTT.
   Nick O'Leary
   http://knolleary.net
@@ -102,30 +103,40 @@ PubSubClient::PubSubClient(const char* domain, uint16_t port, MQTT_CALLBACK_SIGN
 }
 
 boolean PubSubClient::connect(const char *id) {
-    return connect(id,NULL,NULL,0,0,0,0);
+    return connect(id,NULL,NULL,0,0,0,0,1);
 }
 
 boolean PubSubClient::connect(const char *id, const char *user, const char *pass) {
-    return connect(id,user,pass,0,0,0,0);
+    return connect(id,user,pass,0,0,0,0,1);
 }
 
 boolean PubSubClient::connect(const char *id, const char* willTopic, uint8_t willQos, boolean willRetain, const char* willMessage) {
-    return connect(id,NULL,NULL,willTopic,willQos,willRetain,willMessage);
+    return connect(id,NULL,NULL,willTopic,willQos,willRetain,willMessage,1);
 }
 
 boolean PubSubClient::connect(const char *id, const char *user, const char *pass, const char* willTopic, uint8_t willQos, boolean willRetain, const char* willMessage) {
+    return connect(id,user,pass,willTopic,willQos,willRetain,willMessage,1);
+}
+
+boolean PubSubClient::connect(const char *id, const char *user, const char *pass, const char* willTopic, uint8_t willQos, boolean willRetain, const char* willMessage, boolean cleanSession) {
     if (!connected()) {
         int result = 0;
 
-        if (domain != NULL) {
+
-            result = _client->connect(this->domain, this->port);
+        if(_client->connected()) {
+            result = 1;
         } else {
-            result = _client->connect(this->ip, this->port);
+            if (domain != NULL) {
+                result = _client->connect(this->domain, this->port);
+            } else {
+                result = _client->connect(this->ip, this->port);
+            }
         }
+        
         if (result == 1) {
             nextMsgId = 1;
             // Leave room in the buffer for header and variable length field
-            uint16_t length = 5;
+            uint16_t length = MQTT_MAX_HEADER_SIZE;
             unsigned int j;
 
 #if MQTT_VERSION == MQTT_VERSION_3_1
@@ -141,9 +152,12 @@ boolean PubSubClient::connect(const char *id, const char *user, const char *pass
 
             uint8_t v;
             if (willTopic) {
-                v = 0x06|(willQos<<3)|(willRetain<<5);
+                v = 0x04|(willQos<<3)|(willRetain<<5);
             } else {
-                v = 0x02;
+                v = 0x00;
+            }
+            if (cleanSession) {
+                v = v|0x02;
             }
 
             if(user != NULL) {
@@ -158,20 +172,26 @@ boolean PubSubClient::connect(const char *id, const char *user, const char *pass
 
             buffer[length++] = ((MQTT_KEEPALIVE) >> 8);
             buffer[length++] = ((MQTT_KEEPALIVE) & 0xFF);
+
+            CHECK_STRING_LENGTH(length,id)
             length = writeString(id,buffer,length);
             if (willTopic) {
+                CHECK_STRING_LENGTH(length,willTopic)
                 length = writeString(willTopic,buffer,length);
+                CHECK_STRING_LENGTH(length,willMessage)
                 length = writeString(willMessage,buffer,length);
             }
 
             if(user != NULL) {
+                CHECK_STRING_LENGTH(length,user)
                 length = writeString(user,buffer,length);
                 if(pass != NULL) {
+                    CHECK_STRING_LENGTH(length,pass)
                     length = writeString(pass,buffer,length);
                 }
             }
 
-            write(MQTTCONNECT,buffer,length-5);
+            write(MQTTCONNECT,buffer,length-MQTT_MAX_HEADER_SIZE);
 
             lastInActivity = lastOutActivity = millis();
 
@@ -184,7 +204,7 @@ boolean PubSubClient::connect(const char *id, const char *user, const char *pass
                 }
             }
             uint8_t llen;
-            uint16_t len = readPacket(&llen);
+            uint32_t len = readPacket(&llen);
 
             if (len == 4) {
                 if (buffer[3] == 0) {
@@ -209,6 +229,7 @@ boolean PubSubClient::connect(const char *id, const char *user, const char *pass
 boolean PubSubClient::readByte(uint8_t * result) {
    uint32_t previousMillis = millis();
    while(!_client->available()) {
+     yield();
      uint32_t currentMillis = millis();
      if(currentMillis - previousMillis >= ((int32_t) MQTT_SOCKET_TIMEOUT * 1000)){
        return false;
@@ -229,21 +250,27 @@ boolean PubSubClient::readByte(uint8_t * result, uint16_t * index){
   return false;
 }
 
-uint16_t PubSubClient::readPacket(uint8_t* lengthLength) {
+uint32_t PubSubClient::readPacket(uint8_t* lengthLength) {
     uint16_t len = 0;
     if(!readByte(buffer, &len)) return 0;
     bool isPublish = (buffer[0]&0xF0) == MQTTPUBLISH;
     uint32_t multiplier = 1;
-    uint16_t length = 0;
+    uint32_t length = 0;
     uint8_t digit = 0;
     uint16_t skip = 0;
     uint8_t start = 0;
 
     do {
+        if (len == 5) {
+            // Invalid remaining length encoding - kill the connection
+            _state = MQTT_DISCONNECTED;
+            _client->stop();
+            return 0;
+        }
         if(!readByte(&digit)) return 0;
         buffer[len++] = digit;
         length += (digit & 127) * multiplier;
-        multiplier *= 128;
+        multiplier <<=7; //multiplier *= 128
     } while ((digit & 128) != 0);
     *lengthLength = len-1;
 
@@ -259,20 +286,22 @@ uint16_t PubSubClient::readPacket(uint8_t* lengthLength) {
         }
     }
 
-    for (uint16_t i = start;i<length;i++) {
+    uint32_t idx = len;
+    for (uint32_t i = start;i<length;i++) {
         if(!readByte(&digit)) return 0;
         if (this->stream) {
-            if (isPublish && len-*lengthLength-2>skip) {
+            if (isPublish && idx-*lengthLength-2>skip) {
                 this->stream->write(digit);
             }
         }
         if (len < MQTT_MAX_PACKET_SIZE) {
             buffer[len] = digit;
+            len++;
         }
-        len++;
+        idx++;
     }
 
-    if (!this->stream && len > MQTT_MAX_PACKET_SIZE) {
+    if (!this->stream && idx > MQTT_MAX_PACKET_SIZE) {
         len = 0; // This will cause the packet to be ignored.
     }
 
@@ -335,6 +364,9 @@ boolean PubSubClient::loop() {
                 } else if (type == MQTTPINGRESP) {
                     pingOutstanding = false;
                 }
+            } else if (!connected()) {
+                // readPacket has closed the connection
+                return false;
             }
         }
         return true;
@@ -343,11 +375,11 @@ boolean PubSubClient::loop() {
 }
 
 boolean PubSubClient::publish(const char* topic, const char* payload) {
-    return publish(topic,(const uint8_t*)payload,strlen(payload),false);
+    return publish(topic,(const uint8_t*)payload, payload ? strlen(payload) : 0,false);
 }
 
 boolean PubSubClient::publish(const char* topic, const char* payload, boolean retained) {
-    return publish(topic,(const uint8_t*)payload,strlen(payload),retained);
+    return publish(topic,(const uint8_t*)payload, payload ? strlen(payload) : 0,retained);
 }
 
 boolean PubSubClient::publish(const char* topic, const uint8_t* payload, unsigned int plength) {
@@ -356,26 +388,34 @@ boolean PubSubClient::publish(const char* topic, const uint8_t* payload, unsigne
 
 boolean PubSubClient::publish(const char* topic, const uint8_t* payload, unsigned int plength, boolean retained) {
     if (connected()) {
-        if (MQTT_MAX_PACKET_SIZE < 5 + 2+strlen(topic) + plength) {
+        if (MQTT_MAX_PACKET_SIZE < MQTT_MAX_HEADER_SIZE + 2+strlen(topic) + plength) {
             // Too long
             return false;
         }
         // Leave room in the buffer for header and variable length field
-        uint16_t length = 5;
+        uint16_t length = MQTT_MAX_HEADER_SIZE;
         length = writeString(topic,buffer,length);
+
+        // Add payload
         uint16_t i;
         for (i=0;i<plength;i++) {
             buffer[length++] = payload[i];
         }
+
+        // Write the header 
         uint8_t header = MQTTPUBLISH;
         if (retained) {
             header |= 1;
         }
-        return write(header,buffer,length-5);
+        return write(header,buffer,length-MQTT_MAX_HEADER_SIZE);
     }
     return false;
 }
 
+boolean PubSubClient::publish_P(const char* topic, const char* payload, boolean retained) {
+    return publish_P(topic, (const uint8_t*)payload, payload ? strlen(payload) : 0, retained);
+}
+
 boolean PubSubClient::publish_P(const char* topic, const uint8_t* payload, unsigned int plength, boolean retained) {
     uint8_t llen = 0;
     uint8_t digit;
@@ -385,6 +425,7 @@ boolean PubSubClient::publish_P(const char* topic, const uint8_t* payload, unsig
     unsigned int i;
     uint8_t header;
     unsigned int len;
+    int expectedLength;
 
     if (!connected()) {
         return false;
@@ -399,8 +440,8 @@ boolean PubSubClient::publish_P(const char* topic, const uint8_t* payload, unsig
     buffer[pos++] = header;
     len = plength + 2 + tlen;
     do {
-        digit = len % 128;
+        digit = len  & 127; //digit = len %128
-        len = len / 128;
+        len >>= 7; //len = len / 128
         if (len > 0) {
             digit |= 0x80;
         }
@@ -418,19 +459,52 @@ boolean PubSubClient::publish_P(const char* topic, const uint8_t* payload, unsig
 
     lastOutActivity = millis();
 
-    return rc == tlen + 4 + plength;
+    expectedLength = 1 + llen + 2 + tlen + plength;
+
+    return (rc == expectedLength);
 }
 
-boolean PubSubClient::write(uint8_t header, uint8_t* buf, uint16_t length) {
+boolean PubSubClient::beginPublish(const char* topic, unsigned int plength, boolean retained) {
+    if (connected()) {
+        // Send the header and variable length field
+        uint16_t length = MQTT_MAX_HEADER_SIZE;
+        length = writeString(topic,buffer,length);
+        uint8_t header = MQTTPUBLISH;
+        if (retained) {
+            header |= 1;
+        }
+        size_t hlen = buildHeader(header, buffer, plength+length-MQTT_MAX_HEADER_SIZE);
+        uint16_t rc = _client->write(buffer+(MQTT_MAX_HEADER_SIZE-hlen),length-(MQTT_MAX_HEADER_SIZE-hlen));
+        lastOutActivity = millis();
+        return (rc == (length-(MQTT_MAX_HEADER_SIZE-hlen)));
+    }
+    return false;
+}
+
+int PubSubClient::endPublish() {
+ return 1;
+}
+
+size_t PubSubClient::write(uint8_t data) {
+    lastOutActivity = millis();
+    return _client->write(data);
+}
+
+size_t PubSubClient::write(const uint8_t *buffer, size_t size) {
+    lastOutActivity = millis();
+    return _client->write(buffer,size);
+}
+
+size_t PubSubClient::buildHeader(uint8_t header, uint8_t* buf, uint16_t length) {
     uint8_t lenBuf[4];
     uint8_t llen = 0;
     uint8_t digit;
     uint8_t pos = 0;
-    uint16_t rc;
     uint16_t len = length;
     do {
-        digit = len % 128;
+
-        len = len / 128;
+        digit = len  & 127; //digit = len %128
+        len >>= 7; //len = len / 128
         if (len > 0) {
             digit |= 0x80;
         }
@@ -440,12 +514,18 @@ boolean PubSubClient::write(uint8_t header, uint8_t* buf, uint16_t length) {
 
     buf[4-llen] = header;
     for (int i=0;i<llen;i++) {
-        buf[5-llen+i] = lenBuf[i];
+        buf[MQTT_MAX_HEADER_SIZE-llen+i] = lenBuf[i];
     }
+    return llen+1; // Full header size is variable length bit plus the 1-byte fixed header
+}
+
+boolean PubSubClient::write(uint8_t header, uint8_t* buf, uint16_t length) {
+    uint16_t rc;
+    uint8_t hlen = buildHeader(header, buf, length);
 
 #ifdef MQTT_MAX_TRANSFER_SIZE
-    uint8_t* writeBuf = buf+(4-llen);
+    uint8_t* writeBuf = buf+(MQTT_MAX_HEADER_SIZE-hlen);
-    uint16_t bytesRemaining = length+1+llen;  //Match the length type
+    uint16_t bytesRemaining = length+hlen;  //Match the length type
     uint8_t bytesToWrite;
     boolean result = true;
     while((bytesRemaining > 0) && result) {
@@ -457,9 +537,9 @@ boolean PubSubClient::write(uint8_t header, uint8_t* buf, uint16_t length) {
     }
     return result;
 #else
-    rc = _client->write(buf+(4-llen),length+1+llen);
+    rc = _client->write(buf+(MQTT_MAX_HEADER_SIZE-hlen),length+hlen);
     lastOutActivity = millis();
-    return (rc == 1+llen+length);
+    return (rc == hlen+length);
 #endif
 }
 
@@ -468,7 +548,7 @@ boolean PubSubClient::subscribe(const char* topic) {
 }
 
 boolean PubSubClient::subscribe(const char* topic, uint8_t qos) {
-    if (qos < 0 || qos > 1) {
+    if (qos > 1) {
         return false;
     }
     if (MQTT_MAX_PACKET_SIZE < 9 + strlen(topic)) {
@@ -477,7 +557,7 @@ boolean PubSubClient::subscribe(const char* topic, uint8_t qos) {
     }
     if (connected()) {
         // Leave room in the buffer for header and variable length field
-        uint16_t length = 5;
+        uint16_t length = MQTT_MAX_HEADER_SIZE;
         nextMsgId++;
         if (nextMsgId == 0) {
             nextMsgId = 1;
@@ -486,7 +566,7 @@ boolean PubSubClient::subscribe(const char* topic, uint8_t qos) {
         buffer[length++] = (nextMsgId & 0xFF);
         length = writeString((char*)topic, buffer,length);
         buffer[length++] = qos;
-        return write(MQTTSUBSCRIBE|MQTTQOS1,buffer,length-5);
+        return write(MQTTSUBSCRIBE|MQTTQOS1,buffer,length-MQTT_MAX_HEADER_SIZE);
     }
     return false;
 }
@@ -497,7 +577,7 @@ boolean PubSubClient::unsubscribe(const char* topic) {
         return false;
     }
     if (connected()) {
-        uint16_t length = 5;
+        uint16_t length = MQTT_MAX_HEADER_SIZE;
         nextMsgId++;
         if (nextMsgId == 0) {
             nextMsgId = 1;
@@ -505,7 +585,7 @@ boolean PubSubClient::unsubscribe(const char* topic) {
         buffer[length++] = (nextMsgId >> 8);
         buffer[length++] = (nextMsgId & 0xFF);
         length = writeString(topic, buffer,length);
-        return write(MQTTUNSUBSCRIBE|MQTTQOS1,buffer,length-5);
+        return write(MQTTUNSUBSCRIBE|MQTTQOS1,buffer,length-MQTT_MAX_HEADER_SIZE);
     }
     return false;
 }
@@ -515,6 +595,7 @@ void PubSubClient::disconnect() {
     buffer[1] = 0;
     _client->write(buffer,2);
     _state = MQTT_DISCONNECTED;
+    _client->flush();
     _client->stop();
     lastInActivity = lastOutActivity = millis();
 }
@@ -545,6 +626,8 @@ boolean PubSubClient::connected() {
                 _client->flush();
                 _client->stop();
             }
+        } else {
+            return this->_state == MQTT_CONNECTED;
         }
     }
     return rc;

src/PubSubClient.h

@@ -73,14 +73,19 @@
 #define MQTTQOS1        (1 << 1)
 #define MQTTQOS2        (2 << 1)
 
-#ifdef ESP8266
+// Maximum size of fixed header and variable length size header
+#define MQTT_MAX_HEADER_SIZE 5
+
+#if defined(ESP8266) || defined(ESP32)
 #include <functional>
 #define MQTT_CALLBACK_SIGNATURE std::function<void(char*, uint8_t*, unsigned int)> callback
 #else
 #define MQTT_CALLBACK_SIGNATURE void (*callback)(char*, uint8_t*, unsigned int)
 #endif
 
-class PubSubClient {
+#define CHECK_STRING_LENGTH(l,s) if (l+2+strlen(s) > MQTT_MAX_PACKET_SIZE) {_client->stop();return false;}
+
+class PubSubClient : public Print {
 private:
    Client* _client;
    uint8_t buffer[MQTT_MAX_PACKET_SIZE];
@@ -89,11 +94,16 @@ private:
    unsigned long lastInActivity;
    bool pingOutstanding;
    MQTT_CALLBACK_SIGNATURE;
-   uint16_t readPacket(uint8_t*);
+   uint32_t readPacket(uint8_t*);
    boolean readByte(uint8_t * result);
    boolean readByte(uint8_t * result, uint16_t * index);
    boolean write(uint8_t header, uint8_t* buf, uint16_t length);
    uint16_t writeString(const char* string, uint8_t* buf, uint16_t pos);
+   // Build up the header ready to send
+   // Returns the size of the header
+   // Note: the header is built at the end of the first MQTT_MAX_HEADER_SIZE bytes, so will start
+   //       (MQTT_MAX_HEADER_SIZE - <returned size>) bytes into the buffer
+   size_t buildHeader(uint8_t header, uint8_t* buf, uint16_t length);
    IPAddress ip;
    const char* domain;
    uint16_t port;
@@ -126,12 +136,31 @@ public:
    boolean connect(const char* id, const char* user, const char* pass);
    boolean connect(const char* id, const char* willTopic, uint8_t willQos, boolean willRetain, const char* willMessage);
    boolean connect(const char* id, const char* user, const char* pass, const char* willTopic, uint8_t willQos, boolean willRetain, const char* willMessage);
+   boolean connect(const char* id, const char* user, const char* pass, const char* willTopic, uint8_t willQos, boolean willRetain, const char* willMessage, boolean cleanSession);
    void disconnect();
    boolean publish(const char* topic, const char* payload);
    boolean publish(const char* topic, const char* payload, boolean retained);
    boolean publish(const char* topic, const uint8_t * payload, unsigned int plength);
    boolean publish(const char* topic, const uint8_t * payload, unsigned int plength, boolean retained);
+   boolean publish_P(const char* topic, const char* payload, boolean retained);
    boolean publish_P(const char* topic, const uint8_t * payload, unsigned int plength, boolean retained);
+   // Start to publish a message.
+   // This API:
+   //   beginPublish(...)
+   //   one or more calls to write(...)
+   //   endPublish()
+   // Allows for arbitrarily large payloads to be sent without them having to be copied into
+   // a new buffer and held in memory at one time
+   // Returns 1 if the message was started successfully, 0 if there was an error
+   boolean beginPublish(const char* topic, unsigned int plength, boolean retained);
+   // Finish off this publish message (started with beginPublish)
+   // Returns 1 if the packet was sent successfully, 0 if there was an error
+   int endPublish();
+   // Write a single byte of payload (only to be used with beginPublish/endPublish)
+   virtual size_t write(uint8_t);
+   // Write size bytes from buffer into the payload (only to be used with beginPublish/endPublish)
+   // Returns the number of bytes written
+   virtual size_t write(const uint8_t *buffer, size_t size);
    boolean subscribe(const char* topic);
    boolean subscribe(const char* topic, uint8_t qos);
    boolean unsubscribe(const char* topic);

tests/src/connect_spec.cpp

@@ -98,6 +98,33 @@ int test_connect_fails_on_bad_rc() {
     END_IT
 }
 
+int test_connect_non_clean_session() {
+    IT("sends a properly formatted non-clean session connect packet and succeeds");
+    ShimClient shimClient;
+
+    shimClient.setAllowConnect(true);
+    byte expectServer[] = { 172, 16, 0, 2 };
+    shimClient.expectConnect(expectServer,1883);
+    byte connect[] = {0x10,0x18,0x0,0x4,0x4d,0x51,0x54,0x54,0x4,0x0,0x0,0xf,0x0,0xc,0x63,0x6c,0x69,0x65,0x6e,0x74,0x5f,0x74,0x65,0x73,0x74,0x31};
+    byte connack[] = { 0x20, 0x02, 0x00, 0x00 };
+
+    shimClient.expect(connect,26);
+    shimClient.respond(connack,4);
+
+    PubSubClient client(server, 1883, callback, shimClient);
+    int state = client.state();
+    IS_TRUE(state == MQTT_DISCONNECTED);
+
+    int rc = client.connect((char*)"client_test1",0,0,0,0,0,0,0);
+    IS_TRUE(rc);
+    IS_FALSE(shimClient.error());
+
+    state = client.state();
+    IS_TRUE(state == MQTT_CONNECTED);
+
+    END_IT
+}
+
 int test_connect_accepts_username_password() {
     IT("accepts a username and password");
     ShimClient shimClient;
@@ -133,6 +160,23 @@ int test_connect_accepts_username_no_password() {
 
     END_IT
 }
+int test_connect_accepts_username_blank_password() {
+    IT("accepts a username and blank password");
+    ShimClient shimClient;
+    shimClient.setAllowConnect(true);
+
+    byte connect[] = { 0x10,0x20,0x0,0x4,0x4d,0x51,0x54,0x54,0x4,0xc2,0x0,0xf,0x0,0xc,0x63,0x6c,0x69,0x65,0x6e,0x74,0x5f,0x74,0x65,0x73,0x74,0x31,0x0,0x4,0x75,0x73,0x65,0x72,0x0,0x0};
+    byte connack[] = { 0x20, 0x02, 0x00, 0x00 };
+    shimClient.expect(connect,0x26);
+    shimClient.respond(connack,4);
+
+    PubSubClient client(server, 1883, callback, shimClient);
+    int rc = client.connect((char*)"client_test1",(char*)"user",(char*)"pass");
+    IS_TRUE(rc);
+    IS_FALSE(shimClient.error());
+
+    END_IT
+}
 
 int test_connect_ignores_password_no_username() {
     IT("ignores a password but no username");
@@ -239,10 +283,12 @@ int test_connect_disconnect_connect() {
 int main()
 {
     SUITE("Connect");
+
     test_connect_fails_no_network();
     test_connect_fails_on_no_response();
 
     test_connect_properly_formatted();
+    test_connect_non_clean_session();
     test_connect_accepts_username_password();
     test_connect_fails_on_bad_rc();
     test_connect_properly_formatted_hostname();

tests/src/lib/Arduino.h

@@ -5,6 +5,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <math.h>
+#include "Print.h"
 
 
 extern "C"{
@@ -20,4 +21,6 @@ extern "C"{
 #define PROGMEM
 #define pgm_read_byte_near(x) *(x)
 
+#define yield(x) {}
+
 #endif // Arduino_h

tests/src/lib/Buffer.cpp

@@ -2,9 +2,13 @@
 #include "Arduino.h"
 
 Buffer::Buffer() {
+    this->pos = 0;
+    this->length = 0;
 }
 
 Buffer::Buffer(uint8_t* buf, size_t size) {
+    this->pos = 0;
+    this->length = 0;
     this->add(buf,size);
 }
 bool Buffer::available() {

tests/src/lib/Print.h

@@ -0,0 +1,28 @@
+/*
+ Print.h - Base class that provides print() and println()
+ Copyright (c) 2008 David A. Mellis.  All right reserved.
+
+ This library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ This library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with this library; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifndef Print_h
+#define Print_h
+
+class Print {
+    public:
+        virtual size_t write(uint8_t) = 0;
+};
+
+#endif

tests/src/receive_spec.cpp

@@ -160,8 +160,37 @@ int test_receive_oversized_message() {
     END_IT
 }
 
+int test_drop_invalid_remaining_length_message() {
+    IT("drops invalid remaining length message");
+    reset_callback();
+
+    ShimClient shimClient;
+    shimClient.setAllowConnect(true);
+
+    byte connack[] = { 0x20, 0x02, 0x00, 0x00 };
+    shimClient.respond(connack,4);
+
+    PubSubClient client(server, 1883, callback, shimClient);
+    int rc = client.connect((char*)"client_test1");
+    IS_TRUE(rc);
+
+    byte publish[] = {0x30,0x92,0x92,0x92,0x92,0x01,0x0,0x5,0x74,0x6f,0x70,0x69,0x63,0x70,0x61,0x79,0x6c,0x6f,0x61,0x64};
+    shimClient.respond(publish,20);
+
+    rc = client.loop();
+
+    IS_FALSE(rc);
+
+    IS_FALSE(callback_called);
+
+    IS_FALSE(shimClient.error());
+
+    END_IT
+}
+
+
 int test_receive_oversized_stream_message() {
-    IT("drops an oversized message");
+    IT("receive an oversized streamed message");
     reset_callback();
 
     Stream stream;
@@ -193,7 +222,7 @@ int test_receive_oversized_stream_message() {
 
     IS_TRUE(callback_called);
     IS_TRUE(strcmp(lastTopic,"topic")==0);
-    IS_TRUE(lastLength == length-9);
+    IS_TRUE(lastLength == MQTT_MAX_PACKET_SIZE-9);
 
     IS_FALSE(stream.error());
     IS_FALSE(shimClient.error());
@@ -241,6 +270,7 @@ int main()
     test_receive_callback();
     test_receive_stream();
     test_receive_max_sized_message();
+    test_drop_invalid_remaining_length_message();
     test_receive_oversized_message();
     test_receive_oversized_stream_message();
     test_receive_qos1();