UDP multicast APIs fix

fix #74, fix #7

Author: igrr

hardware/esp8266com/esp8266/libraries/ESP8266WiFi/keywords.txt

@@ -33,6 +33,7 @@ flush	KEYWORD2
 stop	KEYWORD2
 connected	KEYWORD2
 begin	KEYWORD2
+beginMulticast	KEYWORD2
 disconnect	KEYWORD2
 macAddress	KEYWORD2
 localIP	KEYWORD2
@@ -43,6 +44,7 @@ BSSID		KEYWORD2
 RSSI	KEYWORD2
 encryptionType	KEYWORD2
 beginPacket	KEYWORD2
+beginPacketMulticast	KEYWORD2
 endPacket	KEYWORD2
 parsePacket	KEYWORD2
 remoteIP	KEYWORD2

hardware/esp8266com/esp8266/libraries/ESP8266WiFi/src/WiFiUdp.cpp

@@ -142,22 +142,33 @@ int WiFiUDP::beginPacket(IPAddress ip, uint16_t port)
     return (_ctx->connect(addr, port)) ? 1 : 0;
 }
 
-int WiFiUDP::endPacket()
+int WiFiUDP::beginPacketMulticast(IPAddress multicastAddress, uint16_t port, 
+    IPAddress interfaceAddress, int ttl)
 {
-    if (!_ctx)
-        return 0;
+    ip_addr_t mcastAddr;
+    mcastAddr.addr = multicastAddress;
+    ip_addr_t ifaceAddr;
+    ifaceAddr.addr = interfaceAddress;
 
-    _ctx->send();
+    if (!_ctx) {
+        _ctx = new UdpContext;
+        _ctx->ref();
+    }
+    if (!_ctx->connect(mcastAddr, port)) {
+        return 0;
+    }
+    _ctx->setMulticastInterface(ifaceAddr);
+    _ctx->setMulticastTTL(ttl);
     return 1;
 }
 
-int WiFiUDP::endPacketMulticast(IPAddress ip, uint16_t port)
+int WiFiUDP::endPacket()
 {
     if (!_ctx)
         return 0;
-    ip_addr_t addr;
-    addr.addr = (uint32_t) ip;
-    _ctx->send(&addr, port);
+
+    _ctx->send();
+    _ctx->disconnect();
     return 1;
 }
 

hardware/esp8266com/esp8266/libraries/ESP8266WiFi/src/WiFiUdp.h

@@ -40,9 +40,13 @@ class WiFiUDP : public UDP {
 
   operator bool() const { return _ctx != 0; }
 
-  virtual uint8_t begin(uint16_t port);	// initialize, start listening on specified port. Returns 1 if successful, 0 if there are no sockets available to use
-  virtual void stop();  // Finish with the UDP socket
-  uint8_t beginMulticast(IPAddress interfaceAddr, IPAddress multicast, uint16_t port); // connect to a multicast group and listen on the given port
+  // initialize, start listening on specified port. 
+  // Returns 1 if successful, 0 if there are no sockets available to use
+  virtual uint8_t begin(uint16_t port);	
+  // Finish with the UDP connetion
+  virtual void stop();
+  // join a multicast group and listen on the given port
+  uint8_t beginMulticast(IPAddress interfaceAddr, IPAddress multicast, uint16_t port); 
 
   // Sending UDP packets
 
@@ -52,12 +56,19 @@ class WiFiUDP : public UDP {
   // Start building up a packet to send to the remote host specific in host and port
   // Returns 1 if successful, 0 if there was a problem resolving the hostname or port
   virtual int beginPacket(const char *host, uint16_t port);
+  // Start building up a packet to send to the multicast address
+  // multicastAddress - muticast address to send to
+  // interfaceAddress - the local IP address of the interface that should be used
+  //                    use WiFi.localIP() or WiFi.softAPIP() depending on the interface you need
+  // ttl              - multicast packet TTL (default is 1)
+  // Returns 1 if successful, 0 if there was a problem with the supplied IP address or port
+  virtual int beginPacketMulticast(IPAddress multicastAddress, 
+                                   uint16_t port, 
+                                   IPAddress interfaceAddress, 
+                                   int ttl = 1);
   // Finish off this packet and send it
   // Returns 1 if the packet was sent successfully, 0 if there was an error
   virtual int endPacket();
-  // Send the packet to a multicast address
-  // Returns 1 if the packet was sent successfully, 0 if there was an error
-  int endPacketMulticast(IPAddress ip, uint16_t port);
   // Write a single byte into the packet
   virtual size_t write(uint8_t);
   // Write size bytes from buffer into the packet

hardware/esp8266com/esp8266/libraries/ESP8266WiFi/src/include/UdpContext.h

@@ -94,6 +94,21 @@ class UdpContext
         udp_disconnect(_pcb);
     }
 
+    void setMulticastInterface(ip_addr_t addr)
+    {
+        // newer versions of lwip have a macro to set the multicast ip
+        // udp_set_multicast_netif_addr(_pcb, addr);
+        _pcb->multicast_ip = addr;
+    }
+
+    void setMulticastTTL(int ttl)
+    {
+        // newer versions of lwip have an additional field (mcast_ttl) for this purpose
+        // and a macro to set it instead of direct field access
+        // udp_set_multicast_ttl(_pcb, ttl);
+        _pcb->ttl = ttl;
+    }
+
     size_t getSize() const
     {
         if (!_rx_buf)

hardware/esp8266com/esp8266/libraries/ESP8266mDNS/ESP8266mDNS.cpp

@@ -62,6 +62,7 @@ MDNSResponder::~MDNSResponder() {
 
 bool MDNSResponder::begin(const char* domain, IPAddress addr, uint32_t ttlSeconds)
 { 
+  _localAddr = addr;
   // Construct DNS request/response fully qualified domain name of form:
   // <domain length>, <domain characters>, 5, "local"
   size_t n = strlen(domain);
@@ -190,8 +191,9 @@ void MDNSResponder::update() {
         Serial.print("responding, i=");
         Serial.println(i);
 #endif
+        _mdnsConn.beginPacketMulticast(IPAddress(224, 0, 0, 251), 5353, _localAddr);
         _mdnsConn.write(_response, _responseLen);
-        _mdnsConn.endPacketMulticast(IPAddress(224, 0, 0, 251), 5353);
+        _mdnsConn.endPacket();
         _index = 0;
       }
     }

hardware/esp8266com/esp8266/libraries/ESP8266mDNS/ESP8266mDNS.h

@@ -64,6 +64,8 @@ class MDNSResponder {
   int _responseLen;
   // Socket for MDNS communication
   WiFiUDP _mdnsConn;
+  // local IP Address
+  IPAddress _localAddr;
 };
 
 #endif //ESP8266MDNS_H

hardware/esp8266com/esp8266/libraries/ESP8266mDNS/examples/mDNS_Web_Server/mDNS_Web_Server.ino

@@ -53,7 +53,6 @@ void setup(void)
   //   the fully-qualified domain name is "esp8266.local"
   // - second argument is the IP address to advertise
   //   we send our IP address on the WiFi network
-  //   Note: for AP mode we would use WiFi.softAPIP()!
   if (!mdns.begin("esp8266", WiFi.localIP())) {
     Serial.println("Error setting up MDNS responder!");
     while(1) {