Revert breaking change to callback signature

closes #44

library.json

@@ -0,0 +1,17 @@
+{
+    "name": "PubSubClient",
+    "keywords": "ethernet, mqtt, m2m, iot",
+    "description": "A client library for MQTT messaging. MQTT is a lightweight messaging protocol ideal for small devices. This library allows you to send and receive MQTT messages. It supports the latest MQTT 3.1.1 protocol and can be configured to use the older MQTT 3.1 if needed. It supports all Arduino Ethernet Client compatible hardware, including the Intel Galileo/Edison, ESP8266 and TI CC3000.",
+    "repository": {
+        "type": "git",
+        "url": "https://github.com/knolleary/pubsubclient.git"
+    },
+    "version": "2.6",
+    "exclude": "tests",
+    "examples": "examples/*/*.ino",
+    "frameworks": "arduino",
+    "platforms": [
+        "atmelavr",
+        "espressif"
+    ]
+}

library.properties

@@ -1,5 +1,5 @@
 name=PubSubClient
-version=2.4
+version=2.6
 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

@@ -122,7 +122,7 @@ boolean PubSubClient::connect(const char *id, const char *user, const char *pass
         } else {
             result = _client->connect(this->ip, this->port);
         }
-        if (result) {
+        if (result == 1) {
             nextMsgId = 1;
             // Leave room in the buffer for header and variable length field
             uint16_t length = 5;
@@ -570,7 +570,7 @@ PubSubClient& PubSubClient::setServer(const char * domain, uint16_t port) {
     return *this;
 }
 
-PubSubClient& PubSubClient::setCallback(void(*callback)(char*,uint8_t*,unsigned int)){
+PubSubClient& PubSubClient::setCallback(MQTT_CALLBACK_SIGNATURE) {
     this->callback = callback;
     return *this;
 }

src/PubSubClient.h

@@ -17,16 +17,24 @@
 
 // MQTT_VERSION : Pick the version
 //#define MQTT_VERSION MQTT_VERSION_3_1
+#ifndef MQTT_VERSION
 #define MQTT_VERSION MQTT_VERSION_3_1_1
+#endif
 
 // MQTT_MAX_PACKET_SIZE : Maximum packet size
+#ifndef MQTT_MAX_PACKET_SIZE
 #define MQTT_MAX_PACKET_SIZE 128
+#endif
 
 // MQTT_KEEPALIVE : keepAlive interval in Seconds
+#ifndef MQTT_KEEPALIVE
 #define MQTT_KEEPALIVE 15
+#endif
 
 // MQTT_SOCKET_TIMEOUT: socket timeout interval in Seconds
+#ifndef MQTT_SOCKET_TIMEOUT
 #define MQTT_SOCKET_TIMEOUT 15
+#endif
 
 // MQTT_MAX_TRANSFER_SIZE : limit how much data is passed to the network client
 //  in each write call. Needed for the Arduino Wifi Shield. Leave undefined to
@@ -65,7 +73,12 @@
 #define MQTTQOS1        (1 << 1)
 #define MQTTQOS2        (2 << 1)
 
+#ifdef ESP8266
+#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 {
 private: