core: new core event for received datagrams

- event type defined as SREV_NET_DGRAM_IN
- allow modules to get a callback when a udp datagram is received
- offers the possibility to handle different content sent via datagram,
  such as HEP from Homer project, without invading the core with new
  code

events.c

@@ -81,6 +81,11 @@ int sr_event_register_cb(int type, sr_event_cb_f f)
 					_sr_events_list.pkg_set_real_used = f;
 				else return -1;
 			break;
+		case SREV_NET_DGRAM_IN:
+				if(_sr_events_list.net_dgram_in==0)
+					_sr_events_list.net_dgram_in = f;
+				else return -1;
+			break;
 		default:
 			return -1;
 	}
@@ -154,6 +159,12 @@ int sr_event_exec(int type, void *data)
 					ret = _sr_events_list.pkg_set_real_used(data);
 					return ret;
 				} else return 1;
+		case SREV_NET_DGRAM_IN:
+				if(unlikely(_sr_events_list.net_dgram_in!=0))
+				{
+					ret = _sr_events_list.net_dgram_in(data);
+					return ret;
+				} else return 1;
 		default:
 			return -1;
 	}

events.h

@@ -29,6 +29,7 @@
 #define SREV_CFG_RUN_ACTION		4
 #define SREV_PKG_SET_USED		5
 #define SREV_PKG_SET_REAL_USED	6
+#define SREV_NET_DGRAM_IN		7
 
 typedef int (*sr_event_cb_f)(void *data);
 
@@ -39,6 +40,7 @@ typedef struct sr_event_cb {
 	sr_event_cb_f run_action;
 	sr_event_cb_f pkg_set_used;
 	sr_event_cb_f pkg_set_real_used;
+	sr_event_cb_f net_dgram_in;
 } sr_event_cb_t;
 
 void sr_event_cb_init(void);

udp_server.c

@@ -75,6 +75,7 @@
 #include "mem/mem.h"
 #include "ip_addr.h"
 #include "cfg/cfg_struct.h"
+#include "events.h"
 #ifdef USE_RAW_SOCKS
 #include "raw_sock.h"
 #endif /* USE_RAW_SOCKS */
@@ -475,6 +476,17 @@ int udp_rcv_loop()
 		su2ip_addr(&ri.src_ip, from);
 		ri.src_port=su_getport(from);
 
+		if(unlikely(sr_event_enabled(SREV_NET_DGRAM_IN)))
+		{
+			void *sredp[3];
+			sredp[0] = (void*)buf;
+			sredp[1] = (void*)(&len);
+			sredp[2] = (void*)(&ri);
+			if(sr_event_exec(SREV_NET_DGRAM_IN, (void*)sredp)<0) {
+				/* data handled by callback - continue to next packet */
+				continue;
+			}
+		}
 #ifndef NO_ZERO_CHECKS
 #ifdef USE_STUN
 		/* STUN support can be switched off even if it's compiled */