ESP8266mDNS using the provided IP in the begin method (esp8266#2349)

this fix forces the mDNS to use the provided IP in the begin method
instead of the auto detected IP. this is required if the ESP8266 starts
in the AP_STA mode and activates only the AP initially.

libraries/ESP8266mDNS/ESP8266mDNS.cpp

@@ -142,26 +142,39 @@ MDNSResponder::~MDNSResponder() {
   _answers = 0;
 }
 
-bool MDNSResponder::begin(const char* hostname){
-  size_t n = strlen(hostname);
+bool MDNSResponder::begin(const char* hostName){
+  return _begin(hostName, 0, 120);
+}
+
+bool MDNSResponder::begin(const char* hostName, IPAddress ip, uint32_t ttl){
+  return _begin(hostName, ip, ttl);
+}
+
+bool MDNSResponder::_begin(const char *hostName, uint32_t ip, uint32_t ttl){
+  size_t n = strlen(hostName);
   if (n > 63) { // max size for a single label.
     return false;
   }
 
+  _ip = ip;
+
   // Copy in hostname characters as lowercase
-  _hostName = hostname;
+  _hostName = hostName;
   _hostName.toLowerCase();
 
   // If instance name is not already set copy hostname to instance name
-  if (_instanceName.equals("") ) _instanceName=hostname;
+  if (_instanceName.equals("") ) _instanceName=hostName;
 
-  _gotIPHandler = WiFi.onStationModeGotIP([this](const WiFiEventStationModeGotIP& event){
-    _restart();
-  });
+  //only if the IP hasn't been set manually, use the events
+  if (ip == 0) {
+    _gotIPHandler = WiFi.onStationModeGotIP([this](const WiFiEventStationModeGotIP& event){
+      _restart();
+    });
 
-  _disconnectedHandler = WiFi.onStationModeDisconnected([this](const WiFiEventStationModeDisconnected& event) {
-    _restart();
-  });
+    _disconnectedHandler = WiFi.onStationModeDisconnected([this](const WiFiEventStationModeDisconnected& event) {
+      _restart();
+    });
+  }
 
   return _listen();
 }
@@ -442,7 +455,11 @@ uint16_t MDNSResponder::_getServicePort(char *name, char *proto){
 
 uint32_t MDNSResponder::_getOurIp(){
   int mode = wifi_get_opmode();
-  if(mode & STATION_MODE){
+
+  //if has a manually set IP use this
+  if(_ip){
+    return _ip;
+  } else if(mode & STATION_MODE){
     struct ip_info staIpInfo;
     wifi_get_ip_info(STATION_IF, &staIpInfo);
     return staIpInfo.ip.addr;

libraries/ESP8266mDNS/ESP8266mDNS.h

@@ -63,9 +63,7 @@ class MDNSResponder {
   ~MDNSResponder();
   bool begin(const char* hostName);
   //for compatibility
-  bool begin(const char* hostName, IPAddress ip, uint32_t ttl=120){
-    return begin(hostName);
-  }
+  bool begin(const char* hostName, IPAddress ip, uint32_t ttl=120);
   void update();
 
   void addService(char *service, char *proto, uint16_t port);
@@ -116,8 +114,9 @@ class MDNSResponder {
   bool _waitingForAnswers;
   WiFiEventHandler _disconnectedHandler;
   WiFiEventHandler _gotIPHandler;
-
+  uint32_t _ip;
 
+  bool _begin(const char* hostName, uint32_t ip, uint32_t ttl);
   uint32_t _getOurIp();
   uint16_t _getServicePort(char *service, char *proto);
   MDNSTxt * _getServiceTxt(char *name, char *proto);