Added SSDP search example

examples/udp-ssdp-search/Makefile

@@ -0,0 +1,10 @@
+PROG ?= example
+
+all: $(PROG)
+	$(RUN) ./$(PROG) $(ARGS)
+
+$(PROG): main.c
+	$(CC) ../../mongoose.c -I../.. -W -Wall $(CFLAGS) -o $(PROG) main.c
+
+clean:
+	rm -rf $(PROG) *.o *.dSYM *.gcov *.gcno *.gcda *.obj *.exe *.ilk *.pdb

examples/udp-ssdp-search/main.c

@@ -0,0 +1,36 @@
+// Copyright (c) 2022 Cesanta Software Limited
+// All rights reserved
+
+#include "mongoose.h"
+
+static const char *s_ssdp_url = "udp://239.255.255.250:1900";
+
+static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
+  if (ev == MG_EV_OPEN) c->is_hexdumping = 1;
+  LOG(LL_DEBUG, ("%p got event: %d %p %p", c, ev, ev_data, fn_data));
+}
+
+static void tfn(void *param) {
+  struct mg_connection *c = param;
+  if (c == NULL) return;
+  LOG(LL_INFO, ("Sending M-SEARCH"));
+  mg_printf(c, "%s",
+            "M-SEARCH * HTTP/1.1\r\n"
+            "HOST: 239.255.255.250:1900\r\n"
+            "MAN: \"ssdp:discover\"\r\n"
+            "ST: urn:schemas-upnp-org:device:MediaRenderer:1\r\n"
+            "MX: 5\r\n"
+            "\r\n");
+}
+
+int main(void) {
+  struct mg_mgr mgr;
+  struct mg_timer timer;
+  static struct mg_connection *c;
+  mg_mgr_init(&mgr);
+  c = mg_connect(&mgr, s_ssdp_url, fn, NULL);
+  mg_timer_init(&timer, 2000, MG_TIMER_REPEAT | MG_TIMER_RUN_NOW, tfn, c);
+  while (true) mg_mgr_poll(&mgr, 200);
+  mg_mgr_free(&mgr);
+  return 0;
+}