diff --git a/.gitignore b/.gitignore
index 1c3ba189..a42cc406 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,5 @@
 tests/bin
+.pioenvs
+.piolibdeps
+.clang_complete
+.gcc-flags.json
diff --git a/CHANGES.txt b/CHANGES.txt
index 8c8bef64..ff4da62a 100755
--- a/CHANGES.txt
+++ b/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
 
diff --git a/README.md b/README.md
index c3b5cce4..2751cb52 100644
--- a/README.md
+++ b/README.md
@@ -8,14 +8,14 @@ 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` or at runtime
-   using PubSubClient::setBufferSize().
+ - The maximum message size, including header, is **256 bytes** by default. This
+   is configurable via `MQTT_MAX_PACKET_SIZE` in `PubSubClient.h` or can be changed
+   by calling `PubSubClient::setBufferSize(size)`.
  - 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
@@ -38,6 +38,7 @@ 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
diff --git a/examples/mqtt_esp8266/mqtt_esp8266.ino b/examples/mqtt_esp8266/mqtt_esp8266.ino
index 34333c9c..7e6effd2 100644
--- a/examples/mqtt_esp8266/mqtt_esp8266.ino
+++ b/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>
@@ -34,8 +29,9 @@ const char* mqtt_server = "broker.mqtt-dashboard.com";
 
 WiFiClient espClient;
 PubSubClient client(espClient);
-long lastMsg = 0;
-char msg[50];
+unsigned long lastMsg = 0;
+#define MSG_BUFFER_SIZE	(50)
+char msg[MSG_BUFFER_SIZE];
 int value = 0;
 
 void setup_wifi() {
@@ -46,6 +42,7 @@ void setup_wifi() {
   Serial.print("Connecting to ");
   Serial.println(ssid);
 
+  WiFi.mode(WIFI_STA);
   WiFi.begin(ssid, password);
 
   while (WiFi.status() != WL_CONNECTED) {
@@ -74,7 +71,7 @@ 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
   }
@@ -120,11 +117,11 @@ void loop() {
   }
   client.loop();
 
-  long now = millis();
+  unsigned long now = millis();
   if (now - lastMsg > 2000) {
     lastMsg = now;
     ++value;
-    snprintf (msg, 75, "hello world #%ld", value);
+    snprintf (msg, MSG_BUFFER_SIZE, "hello world #%ld", value);
     Serial.print("Publish message: ");
     Serial.println(msg);
     client.publish("outTopic", msg);
diff --git a/examples/mqtt_large_message/mqtt_large_message.ino b/examples/mqtt_large_message/mqtt_large_message.ino
new file mode 100644
index 00000000..e048c3ed
--- /dev/null
+++ b/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();
+}
diff --git a/keywords.txt b/keywords.txt
index b979588f..1ee23d0f 100755
--- a/keywords.txt
+++ b/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
diff --git a/library.json b/library.json
index b9673907..8a36a1c5 100644
--- a/library.json
+++ b/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",
diff --git a/library.properties b/library.properties
index 3ceeda81..1ae97882 100644
--- a/library.properties
+++ b/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.
diff --git a/src/PubSubClient.cpp b/src/PubSubClient.cpp
index 73714bd2..7efe9b0f 100755
--- a/src/PubSubClient.cpp
+++ b/src/PubSubClient.cpp
@@ -1,4 +1,5 @@
 /*
+
   PubSubClient.cpp - A simple client for MQTT.
   Nick O'Leary
   http://knolleary.net
@@ -12,16 +13,16 @@ PubSubClient::PubSubClient() {
     this->_client = NULL;
     this->stream = NULL;
     setCallback(NULL);
-    this->buffer_size = MQTT_MAX_PACKET_SIZE;
-    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
+    this->bufferSize = 0;
+    setBufferSize(MQTT_MAX_PACKET_SIZE);
 }
 
 PubSubClient::PubSubClient(Client& client) {
     this->_state = MQTT_DISCONNECTED;
     setClient(client);
     this->stream = NULL;
-    this->buffer_size = MQTT_MAX_PACKET_SIZE;
-    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
+    this->bufferSize = 0;
+    setBufferSize(MQTT_MAX_PACKET_SIZE);
 }
 
 PubSubClient::PubSubClient(IPAddress addr, uint16_t port, Client& client) {
@@ -29,16 +30,16 @@ PubSubClient::PubSubClient(IPAddress addr, uint16_t port, Client& client) {
     setServer(addr, port);
     setClient(client);
     this->stream = NULL;
-    this->buffer_size = MQTT_MAX_PACKET_SIZE;
-    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
+    this->bufferSize = 0;
+    setBufferSize(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(IPAddress addr, uint16_t port, Client& client, Stream& stream) {
     this->_state = MQTT_DISCONNECTED;
     setServer(addr,port);
     setClient(client);
     setStream(stream);
-    this->buffer_size = MQTT_MAX_PACKET_SIZE;
-    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
+    this->bufferSize = 0;
+    setBufferSize(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(IPAddress addr, uint16_t port, MQTT_CALLBACK_SIGNATURE, Client& client) {
     this->_state = MQTT_DISCONNECTED;
@@ -46,8 +47,8 @@ PubSubClient::PubSubClient(IPAddress addr, uint16_t port, MQTT_CALLBACK_SIGNATUR
     setCallback(callback);
     setClient(client);
     this->stream = NULL;
-    this->buffer_size = MQTT_MAX_PACKET_SIZE;
-    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
+    this->bufferSize = 0;
+    setBufferSize(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(IPAddress addr, uint16_t port, MQTT_CALLBACK_SIGNATURE, Client& client, Stream& stream) {
     this->_state = MQTT_DISCONNECTED;
@@ -55,8 +56,8 @@ PubSubClient::PubSubClient(IPAddress addr, uint16_t port, MQTT_CALLBACK_SIGNATUR
     setCallback(callback);
     setClient(client);
     setStream(stream);
-    this->buffer_size = MQTT_MAX_PACKET_SIZE;
-    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
+    this->bufferSize = 0;
+    setBufferSize(MQTT_MAX_PACKET_SIZE);
 }
 
 PubSubClient::PubSubClient(uint8_t *ip, uint16_t port, Client& client) {
@@ -64,16 +65,16 @@ PubSubClient::PubSubClient(uint8_t *ip, uint16_t port, Client& client) {
     setServer(ip, port);
     setClient(client);
     this->stream = NULL;
-    this->buffer_size = MQTT_MAX_PACKET_SIZE;
-    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
+    this->bufferSize = 0;
+    setBufferSize(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(uint8_t *ip, uint16_t port, Client& client, Stream& stream) {
     this->_state = MQTT_DISCONNECTED;
     setServer(ip,port);
     setClient(client);
     setStream(stream);
-    this->buffer_size = MQTT_MAX_PACKET_SIZE;
-    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
+    this->bufferSize = 0;
+    setBufferSize(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(uint8_t *ip, uint16_t port, MQTT_CALLBACK_SIGNATURE, Client& client) {
     this->_state = MQTT_DISCONNECTED;
@@ -81,8 +82,8 @@ PubSubClient::PubSubClient(uint8_t *ip, uint16_t port, MQTT_CALLBACK_SIGNATURE,
     setCallback(callback);
     setClient(client);
     this->stream = NULL;
-    this->buffer_size = MQTT_MAX_PACKET_SIZE;
-    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
+    this->bufferSize = 0;
+    setBufferSize(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(uint8_t *ip, uint16_t port, MQTT_CALLBACK_SIGNATURE, Client& client, Stream& stream) {
     this->_state = MQTT_DISCONNECTED;
@@ -90,8 +91,8 @@ PubSubClient::PubSubClient(uint8_t *ip, uint16_t port, MQTT_CALLBACK_SIGNATURE,
     setCallback(callback);
     setClient(client);
     setStream(stream);
-    this->buffer_size = MQTT_MAX_PACKET_SIZE;
-    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
+    this->bufferSize = 0;
+    setBufferSize(MQTT_MAX_PACKET_SIZE);
 }
 
 PubSubClient::PubSubClient(const char* domain, uint16_t port, Client& client) {
@@ -99,16 +100,16 @@ PubSubClient::PubSubClient(const char* domain, uint16_t port, Client& client) {
     setServer(domain,port);
     setClient(client);
     this->stream = NULL;
-    this->buffer_size = MQTT_MAX_PACKET_SIZE;
-    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
+    this->bufferSize = 0;
+    setBufferSize(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(const char* domain, uint16_t port, Client& client, Stream& stream) {
     this->_state = MQTT_DISCONNECTED;
     setServer(domain,port);
     setClient(client);
     setStream(stream);
-    this->buffer_size = MQTT_MAX_PACKET_SIZE;
-    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
+    this->bufferSize = 0;
+    setBufferSize(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(const char* domain, uint16_t port, MQTT_CALLBACK_SIGNATURE, Client& client) {
     this->_state = MQTT_DISCONNECTED;
@@ -116,8 +117,8 @@ PubSubClient::PubSubClient(const char* domain, uint16_t port, MQTT_CALLBACK_SIGN
     setCallback(callback);
     setClient(client);
     this->stream = NULL;
-    this->buffer_size = MQTT_MAX_PACKET_SIZE;
-    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
+    this->bufferSize = 0;
+    setBufferSize(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(const char* domain, uint16_t port, MQTT_CALLBACK_SIGNATURE, Client& client, Stream& stream) {
     this->_state = MQTT_DISCONNECTED;
@@ -125,8 +126,8 @@ PubSubClient::PubSubClient(const char* domain, uint16_t port, MQTT_CALLBACK_SIGN
     setCallback(callback);
     setClient(client);
     setStream(stream);
-    this->buffer_size = MQTT_MAX_PACKET_SIZE;
-    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
+    this->bufferSize = 0;
+    setBufferSize(MQTT_MAX_PACKET_SIZE);
 }
 
 PubSubClient::~PubSubClient() {
@@ -134,30 +135,40 @@ PubSubClient::~PubSubClient() {
 }
 
 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
@@ -168,14 +179,17 @@ boolean PubSubClient::connect(const char *id, const char *user, const char *pass
 #define MQTT_HEADER_VERSION_LENGTH 7
 #endif
             for (j = 0;j<MQTT_HEADER_VERSION_LENGTH;j++) {
-                buffer[length++] = d[j];
+                this->buffer[length++] = d[j];
             }
 
             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) {
@@ -185,25 +199,30 @@ boolean PubSubClient::connect(const char *id, const char *user, const char *pass
                     v = v|(0x80>>1);
                 }
             }
+            this->buffer[length++] = v;
 
-            buffer[length++] = v;
+            this->buffer[length++] = ((MQTT_KEEPALIVE) >> 8);
+            this->buffer[length++] = ((MQTT_KEEPALIVE) & 0xFF);
 
-            buffer[length++] = ((MQTT_KEEPALIVE) >> 8);
-            buffer[length++] = ((MQTT_KEEPALIVE) & 0xFF);
-            length = writeString(id,buffer,length);
+            CHECK_STRING_LENGTH(length,id)
+            length = writeString(id,this->buffer,length);
             if (willTopic) {
-                length = writeString(willTopic,buffer,length);
-                length = writeString(willMessage,buffer,length);
+                CHECK_STRING_LENGTH(length,willTopic)
+                length = writeString(willTopic,this->buffer,length);
+                CHECK_STRING_LENGTH(length,willMessage)
+                length = writeString(willMessage,this->buffer,length);
             }
 
             if(user != NULL) {
-                length = writeString(user,buffer,length);
+                CHECK_STRING_LENGTH(length,user)
+                length = writeString(user,this->buffer,length);
                 if(pass != NULL) {
-                    length = writeString(pass,buffer,length);
+                    CHECK_STRING_LENGTH(length,pass)
+                    length = writeString(pass,this->buffer,length);
                 }
             }
 
-            write(MQTTCONNECT,buffer,length-5);
+            write(MQTTCONNECT,this->buffer,length-MQTT_MAX_HEADER_SIZE);
 
             lastInActivity = lastOutActivity = millis();
 
@@ -216,7 +235,7 @@ 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) {
@@ -241,6 +260,7 @@ 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;
@@ -261,53 +281,61 @@ 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;
+    if(!readByte(this->buffer, &len)) return 0;
+    bool isPublish = (this->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;
+    uint32_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;
+        this->buffer[len++] = digit;
         length += (digit & 127) * multiplier;
-        multiplier *= 128;
+        multiplier <<=7; //multiplier *= 128
     } while ((digit & 128) != 0);
     *lengthLength = len-1;
 
     if (isPublish) {
         // Read in topic length to calculate bytes to skip over for Stream writing
-        if(!readByte(buffer, &len)) return 0;
-        if(!readByte(buffer, &len)) return 0;
-        skip = (buffer[*lengthLength+1]<<8)+buffer[*lengthLength+2];
+        if(!readByte(this->buffer, &len)) return 0;
+        if(!readByte(this->buffer, &len)) return 0;
+        skip = (this->buffer[*lengthLength+1]<<8)+this->buffer[*lengthLength+2];
         start = 2;
-        if (buffer[0]&MQTTQOS1) {
+        if (this->buffer[0]&MQTTQOS1) {
             // skip message id
             skip += 2;
         }
     }
+    uint32_t idx = len;
 
-    for (uint16_t i = start;i<length;i++) {
+    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 < this->buffer_size) {
-            buffer[len] = digit;
+
+        if (len < this->bufferSize) {
+            this->buffer[len] = digit;
+            len++;
         }
-        len++;
+        idx++;
     }
 
-    if (!this->stream && len > this->buffer_size) {
+    if (!this->stream && idx > this->bufferSize) {
         len = 0; // This will cause the packet to be ignored.
     }
-
     return len;
 }
 
@@ -320,9 +348,9 @@ boolean PubSubClient::loop() {
                 _client->stop();
                 return false;
             } else {
-                buffer[0] = MQTTPINGREQ;
-                buffer[1] = 0;
-                _client->write(buffer,2);
+                this->buffer[0] = MQTTPINGREQ;
+                this->buffer[1] = 0;
+                _client->write(this->buffer,2);
                 lastOutActivity = t;
                 lastInActivity = t;
                 pingOutstanding = true;
@@ -335,38 +363,41 @@ boolean PubSubClient::loop() {
             uint8_t *payload;
             if (len > 0) {
                 lastInActivity = t;
-                uint8_t type = buffer[0]&0xF0;
+                uint8_t type = this->buffer[0]&0xF0;
                 if (type == MQTTPUBLISH) {
                     if (callback) {
-                        uint16_t tl = (buffer[llen+1]<<8)+buffer[llen+2]; /* topic length in bytes */
-                        memmove(buffer+llen+2,buffer+llen+3,tl); /* move topic inside buffer 1 byte to front */
-                        buffer[llen+2+tl] = 0; /* end the topic as a 'C' string with \x00 */
-                        char *topic = (char*) buffer+llen+2;
+                        uint16_t tl = (this->buffer[llen+1]<<8)+this->buffer[llen+2]; /* topic length in bytes */
+                        memmove(this->buffer+llen+2,this->buffer+llen+3,tl); /* move topic inside buffer 1 byte to front */
+                        this->buffer[llen+2+tl] = 0; /* end the topic as a 'C' string with \x00 */
+                        char *topic = (char*) this->buffer+llen+2;
                         // msgId only present for QOS>0
-                        if ((buffer[0]&0x06) == MQTTQOS1) {
-                            msgId = (buffer[llen+3+tl]<<8)+buffer[llen+3+tl+1];
-                            payload = buffer+llen+3+tl+2;
+                        if ((this->buffer[0]&0x06) == MQTTQOS1) {
+                            msgId = (this->buffer[llen+3+tl]<<8)+this->buffer[llen+3+tl+1];
+                            payload = this->buffer+llen+3+tl+2;
                             callback(topic,payload,len-llen-3-tl-2);
 
-                            buffer[0] = MQTTPUBACK;
-                            buffer[1] = 2;
-                            buffer[2] = (msgId >> 8);
-                            buffer[3] = (msgId & 0xFF);
-                            _client->write(buffer,4);
+                            this->buffer[0] = MQTTPUBACK;
+                            this->buffer[1] = 2;
+                            this->buffer[2] = (msgId >> 8);
+                            this->buffer[3] = (msgId & 0xFF);
+                            _client->write(this->buffer,4);
                             lastOutActivity = t;
 
                         } else {
-                            payload = buffer+llen+3+tl;
+                            payload = this->buffer+llen+3+tl;
                             callback(topic,payload,len-llen-3-tl);
                         }
                     }
                 } else if (type == MQTTPINGREQ) {
-                    buffer[0] = MQTTPINGRESP;
-                    buffer[1] = 0;
-                    _client->write(buffer,2);
+                    this->buffer[0] = MQTTPINGRESP;
+                    this->buffer[1] = 0;
+                    _client->write(this->buffer,2);
                 } else if (type == MQTTPINGRESP) {
                     pingOutstanding = false;
                 }
+            } else if (!connected()) {
+                // readPacket has closed the connection
+                return false;
             }
         }
         return true;
@@ -375,11 +406,11 @@ 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 ? strnlen(payload, this->bufferSize) : 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 ? strnlen(payload, this->bufferSize) : 0,retained);
 }
 
 boolean PubSubClient::publish(const char* topic, const uint8_t* payload, unsigned int plength) {
@@ -388,26 +419,34 @@ 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 (this->buffer_size < 5 + 2+strlen(topic) + plength) {
+        if (this->bufferSize < MQTT_MAX_HEADER_SIZE + 2+strnlen(topic, this->bufferSize) + plength) {
             // Too long
             return false;
         }
         // Leave room in the buffer for header and variable length field
-        uint16_t length = 5;
-        length = writeString(topic,buffer,length);
+        uint16_t length = MQTT_MAX_HEADER_SIZE;
+        length = writeString(topic,this->buffer,length);
+
+        // Add payload
         uint16_t i;
         for (i=0;i<plength;i++) {
-            buffer[length++] = payload[i];
+            this->buffer[length++] = payload[i];
         }
+
+        // Write the header
         uint8_t header = MQTTPUBLISH;
         if (retained) {
             header |= 1;
         }
-        return write(header,buffer,length-5);
+        return write(header,this->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 ? strnlen(payload, this->bufferSize) : 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;
@@ -417,32 +456,33 @@ 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;
     }
 
-    tlen = strlen(topic);
+    tlen = strnlen(topic, this->bufferSize);
 
     header = MQTTPUBLISH;
     if (retained) {
         header |= 1;
     }
-    buffer[pos++] = header;
+    this->buffer[pos++] = header;
     len = plength + 2 + tlen;
     do {
-        digit = len % 128;
-        len = len / 128;
+        digit = len  & 127; //digit = len %128
+        len >>= 7; //len = len / 128
         if (len > 0) {
             digit |= 0x80;
         }
-        buffer[pos++] = digit;
+        this->buffer[pos++] = digit;
         llen++;
     } while(len>0);
 
-    pos = writeString(topic,buffer,pos);
+    pos = writeString(topic,this->buffer,pos);
 
-    rc += _client->write(buffer,pos);
+    rc += _client->write(this->buffer,pos);
 
     for (i=0;i<plength;i++) {
         rc += _client->write((char)pgm_read_byte_near(payload + i));
@@ -450,19 +490,52 @@ 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,this->buffer,length);
+        uint8_t header = MQTTPUBLISH;
+        if (retained) {
+            header |= 1;
+        }
+        size_t hlen = buildHeader(header, this->buffer, plength+length-MQTT_MAX_HEADER_SIZE);
+        uint16_t rc = _client->write(this->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;
         }
@@ -472,12 +545,18 @@ 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);
-    uint16_t bytesRemaining = length+1+llen;  //Match the length type
+    uint8_t* writeBuf = buf+(MQTT_MAX_HEADER_SIZE-hlen);
+    uint16_t bytesRemaining = length+hlen;  //Match the length type
     uint8_t bytesToWrite;
     boolean result = true;
     while((bytesRemaining > 0) && result) {
@@ -489,9 +568,9 @@ 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
 }
 
@@ -500,53 +579,62 @@ boolean PubSubClient::subscribe(const char* topic) {
 }
 
 boolean PubSubClient::subscribe(const char* topic, uint8_t qos) {
-    if (qos < 0 || qos > 1) {
+    size_t topicLength = strnlen(topic, this->bufferSize);
+    if (topic == 0) {
+        return false;
+    }
+    if (qos > 1) {
         return false;
     }
-    if (this->buffer_size < 9 + strlen(topic)) {
+    if (this->bufferSize < 9 + topicLength) {
         // Too long
         return false;
     }
     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;
         }
-        buffer[length++] = (nextMsgId >> 8);
-        buffer[length++] = (nextMsgId & 0xFF);
-        length = writeString((char*)topic, buffer,length);
-        buffer[length++] = qos;
-        return write(MQTTSUBSCRIBE|MQTTQOS1,buffer,length-5);
+        this->buffer[length++] = (nextMsgId >> 8);
+        this->buffer[length++] = (nextMsgId & 0xFF);
+        length = writeString((char*)topic, this->buffer,length);
+        this->buffer[length++] = qos;
+        return write(MQTTSUBSCRIBE|MQTTQOS1,this->buffer,length-MQTT_MAX_HEADER_SIZE);
     }
     return false;
 }
 
 boolean PubSubClient::unsubscribe(const char* topic) {
-    if (this->buffer_size < 9 + strlen(topic)) {
+	size_t topicLength = strnlen(topic, this->bufferSize);
+    if (topic == 0) {
+        return false;
+    }
+    if (this->bufferSize < 9 + topicLength) {
         // Too long
         return false;
     }
     if (connected()) {
-        uint16_t length = 5;
+        uint16_t length = MQTT_MAX_HEADER_SIZE;
         nextMsgId++;
         if (nextMsgId == 0) {
             nextMsgId = 1;
         }
-        buffer[length++] = (nextMsgId >> 8);
-        buffer[length++] = (nextMsgId & 0xFF);
-        length = writeString(topic, buffer,length);
-        return write(MQTTUNSUBSCRIBE|MQTTQOS1,buffer,length-5);
+        this->buffer[length++] = (nextMsgId >> 8);
+        this->buffer[length++] = (nextMsgId & 0xFF);
+        length = writeString(topic, this->buffer,length);
+        return write(MQTTUNSUBSCRIBE|MQTTQOS1,this->buffer,length-MQTT_MAX_HEADER_SIZE);
     }
     return false;
 }
 
 void PubSubClient::disconnect() {
-    buffer[0] = MQTTDISCONNECT;
-    buffer[1] = 0;
-    _client->write(buffer,2);
+    this->buffer[0] = MQTTDISCONNECT;
+    this->buffer[1] = 0;
+    _client->write(this->buffer,2);
     _state = MQTT_DISCONNECTED;
+    _client->flush();
     _client->stop();
     lastInActivity = lastOutActivity = millis();
 }
@@ -577,6 +665,8 @@ boolean PubSubClient::connected() {
                 _client->flush();
                 _client->stop();
             }
+        } else {
+            return this->_state == MQTT_CONNECTED;
         }
     }
     return rc;
@@ -620,11 +710,24 @@ int PubSubClient::state() {
 }
 
 boolean PubSubClient::setBufferSize(uint16_t size) {
-  this->buffer = (uint8_t*)realloc(this->buffer, size);
-  this->buffer_size = size;
-  return (this->buffer == NULL);
+    if (size == 0) {
+        // Cannot set it back to 0
+        return false;
+    }
+    if (this->bufferSize == 0) {
+        this->buffer = (uint8_t*)malloc(size);
+    } else {
+        uint8_t* newBuffer = (uint8_t*)realloc(this->buffer, size);
+        if (newBuffer != NULL) {
+            this->buffer = newBuffer;
+        } else {
+            return false;
+        }
+    }
+    this->bufferSize = size;
+    return (this->buffer != NULL);
 }
 
 uint16_t PubSubClient::getBufferSize() {
-  return this->buffer_size;
+    return this->bufferSize;
 }
diff --git a/src/PubSubClient.h b/src/PubSubClient.h
index c8b0ff14..bd44f2a9 100755
--- a/src/PubSubClient.h
+++ b/src/PubSubClient.h
@@ -23,7 +23,7 @@
 
 // MQTT_MAX_PACKET_SIZE : Maximum packet size. Override with setBufferSize().
 #ifndef MQTT_MAX_PACKET_SIZE
-#define MQTT_MAX_PACKET_SIZE 128
+#define MQTT_MAX_PACKET_SIZE 256
 #endif
 
 // MQTT_KEEPALIVE : keepAlive interval in Seconds
@@ -73,28 +73,38 @@
 #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+strnlen(s, this->bufferSize) > this->bufferSize) {_client->stop();return false;}
+
+class PubSubClient : public Print {
 private:
    Client* _client;
    uint8_t* buffer;
-   uint16_t buffer_size;
+   uint16_t bufferSize;
    uint16_t nextMsgId;
    unsigned long lastOutActivity;
    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;
@@ -125,24 +135,45 @@ class PubSubClient {
    PubSubClient& setClient(Client& client);
    PubSubClient& setStream(Stream& stream);
 
+   boolean setBufferSize(uint16_t size);
+   uint16_t getBufferSize();
+
    boolean connect(const char* id);
    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);
    boolean loop();
    boolean connected();
    int state();
-   boolean setBufferSize(uint16_t size);
-   uint16_t getBufferSize();
+
 };
 
 
diff --git a/tests/src/connect_spec.cpp b/tests/src/connect_spec.cpp
index 69f18646..e27a1f59 100644
--- a/tests/src/connect_spec.cpp
+++ b/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();
diff --git a/tests/src/lib/Arduino.h b/tests/src/lib/Arduino.h
index c6752801..2a00f24b 100644
--- a/tests/src/lib/Arduino.h
+++ b/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
diff --git a/tests/src/lib/Buffer.cpp b/tests/src/lib/Buffer.cpp
index 59a2fbbb..f07759a3 100644
--- a/tests/src/lib/Buffer.cpp
+++ b/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() {
diff --git a/tests/src/lib/Buffer.h b/tests/src/lib/Buffer.h
index f448cade..c6a2cb58 100644
--- a/tests/src/lib/Buffer.h
+++ b/tests/src/lib/Buffer.h
@@ -5,18 +5,18 @@
 
 class Buffer {
 private:
-    uint8_t buffer[1024];
+    uint8_t buffer[2048];
     uint16_t pos;
     uint16_t length;
-    
+
 public:
     Buffer();
     Buffer(uint8_t* buf, size_t size);
-    
+
     virtual bool available();
     virtual uint8_t next();
     virtual void reset();
-    
+
     virtual void add(uint8_t* buf, size_t size);
 };
 
diff --git a/tests/src/lib/Print.h b/tests/src/lib/Print.h
new file mode 100644
index 00000000..02ef77c2
--- /dev/null
+++ b/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
diff --git a/tests/src/publish_spec.cpp b/tests/src/publish_spec.cpp
index 232df0d3..ee3d3bed 100644
--- a/tests/src/publish_spec.cpp
+++ b/tests/src/publish_spec.cpp
@@ -134,6 +134,7 @@ int test_publish_too_long() {
     shimClient.respond(connack,4);
 
     PubSubClient client(server, 1883, callback, shimClient);
+    client.setBufferSize(128);
     int rc = client.connect((char*)"client_test1");
     IS_TRUE(rc);
 
diff --git a/tests/src/receive_spec.cpp b/tests/src/receive_spec.cpp
index 29975190..93e909ae 100644
--- a/tests/src/receive_spec.cpp
+++ b/tests/src/receive_spec.cpp
@@ -20,6 +20,7 @@ void reset_callback() {
 }
 
 void callback(char* topic, byte* payload, unsigned int length) {
+    TRACE("Callback received topic=[" << topic << "] length=" << length << "\n")
     callback_called = true;
     strcpy(lastTopic,topic);
     memcpy(lastPayload,payload,length);
@@ -102,10 +103,15 @@ int test_receive_max_sized_message() {
     shimClient.respond(connack,4);
 
     PubSubClient client(server, 1883, callback, shimClient);
+    int length = 80; // If this is changed to > 128 then the publish packet below
+                     // is no longer valid as it assumes the remaining length
+                     // is a single-byte. Don't make that mistake like I just
+                     // did and lose a whole evening tracking down the issue.
+    client.setBufferSize(length);
     int rc = client.connect((char*)"client_test1");
     IS_TRUE(rc);
 
-    int length = MQTT_MAX_PACKET_SIZE;
+
     byte publish[] = {0x30,length-2,0x0,0x5,0x74,0x6f,0x70,0x69,0x63,0x70,0x61,0x79,0x6c,0x6f,0x61,0x64};
     byte bigPublish[length];
     memset(bigPublish,'A',length);
@@ -137,11 +143,13 @@ int test_receive_oversized_message() {
     byte connack[] = { 0x20, 0x02, 0x00, 0x00 };
     shimClient.respond(connack,4);
 
+    int length = 80; // See comment in test_receive_max_sized_message before changing this value
+
     PubSubClient client(server, 1883, callback, shimClient);
+    client.setBufferSize(length-1);
     int rc = client.connect((char*)"client_test1");
     IS_TRUE(rc);
 
-    int length = MQTT_MAX_PACKET_SIZE+1;
     byte publish[] = {0x30,length-2,0x0,0x5,0x74,0x6f,0x70,0x69,0x63,0x70,0x61,0x79,0x6c,0x6f,0x61,0x64};
     byte bigPublish[length];
     memset(bigPublish,'A',length);
@@ -160,6 +168,34 @@ 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_resize_buffer() {
     IT("receives a message larger than the default maximum");
     reset_callback();
@@ -170,24 +206,36 @@ int test_resize_buffer() {
     byte connack[] = { 0x20, 0x02, 0x00, 0x00 };
     shimClient.respond(connack,4);
 
+    int length = 80; // See comment in test_receive_max_sized_message before changing this value
+
     PubSubClient client(server, 1883, callback, shimClient);
+    client.setBufferSize(length-1);
     int rc = client.connect((char*)"client_test1");
     IS_TRUE(rc);
 
-    int length = MQTT_MAX_PACKET_SIZE+1;
-    client.setBufferSize(length);
     byte publish[] = {0x30,length-2,0x0,0x5,0x74,0x6f,0x70,0x69,0x63,0x70,0x61,0x79,0x6c,0x6f,0x61,0x64};
     byte bigPublish[length];
     memset(bigPublish,'A',length);
     bigPublish[length] = 'B';
     memcpy(bigPublish,publish,16);
+    // Send it twice
+    shimClient.respond(bigPublish,length);
     shimClient.respond(bigPublish,length);
 
     rc = client.loop();
+    IS_TRUE(rc);
+
+    // First message fails as it is too big
+    IS_FALSE(callback_called);
+
+    // Resize the buffer
+    client.setBufferSize(length);
 
+    rc = client.loop();
     IS_TRUE(rc);
 
     IS_TRUE(callback_called);
+
     IS_TRUE(strcmp(lastTopic,"topic")==0);
     IS_TRUE(lastLength == length-9);
     IS_TRUE(memcmp(lastPayload,bigPublish+9,lastLength)==0);
@@ -197,8 +245,9 @@ int test_resize_buffer() {
     END_IT
 }
 
+
 int test_receive_oversized_stream_message() {
-    IT("drops an oversized message");
+    IT("receive an oversized streamed message");
     reset_callback();
 
     Stream stream;
@@ -209,11 +258,13 @@ int test_receive_oversized_stream_message() {
     byte connack[] = { 0x20, 0x02, 0x00, 0x00 };
     shimClient.respond(connack,4);
 
+    int length = 80; // See comment in test_receive_max_sized_message before changing this value
+
     PubSubClient client(server, 1883, callback, shimClient, stream);
+    client.setBufferSize(length-1);
     int rc = client.connect((char*)"client_test1");
     IS_TRUE(rc);
 
-    int length = MQTT_MAX_PACKET_SIZE+1;
     byte publish[] = {0x30,length-2,0x0,0x5,0x74,0x6f,0x70,0x69,0x63,0x70,0x61,0x79,0x6c,0x6f,0x61,0x64};
 
     byte bigPublish[length];
@@ -230,7 +281,8 @@ int test_receive_oversized_stream_message() {
 
     IS_TRUE(callback_called);
     IS_TRUE(strcmp(lastTopic,"topic")==0);
-    IS_TRUE(lastLength == length-9);
+
+    IS_TRUE(lastLength == length-10);
 
     IS_FALSE(stream.error());
     IS_FALSE(shimClient.error());
@@ -278,6 +330,7 @@ int main()
     test_receive_callback();
     test_receive_stream();
     test_receive_max_sized_message();
+    test_drop_invalid_remaining_length_message();
     test_receive_oversized_message();
     test_resize_buffer();
     test_receive_oversized_stream_message();
diff --git a/tests/src/subscribe_spec.cpp b/tests/src/subscribe_spec.cpp
index a4198235..22dc8a44 100644
--- a/tests/src/subscribe_spec.cpp
+++ b/tests/src/subscribe_spec.cpp
@@ -106,6 +106,7 @@ int test_subscribe_too_long() {
     shimClient.respond(connack,4);
 
     PubSubClient client(server, 1883, callback, shimClient);
+    client.setBufferSize(128);
     int rc = client.connect((char*)"client_test1");
     IS_TRUE(rc);