feat: add basic support for libnet

src/Makefile

@@ -1,8 +1,9 @@
 IGMPPROG=igmpgen
-CFLAGS=-Wall
+CFLAGS=-Wall `libnet-config --defines`
+LDFLAGS=`libnet-config --libs`
 
 all:
-	gcc $(CFLAGS) $(IGMPPROG).c -o $(IGMPPROG)
+	gcc $(CFLAGS) $(IGMPPROG).c -o $(IGMPPROG) $(LDFLAGS)
 
 clean:
 	rm -f $(IGMPPROG)

src/igmpgen.c

@@ -1,6 +1,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+
 #include <libnet.h>
 #include <netinet/igmp.h>
 
@@ -30,6 +31,14 @@ void usage(char *name)
 
 int main(int argc, char **argv)
 {
+    /* ip addresses */
+    u_int32_t ip_src = 0;
+    char *ip_src_str = NULL;
+
+    /* libnet stuff */
+    char neterr[LIBNET_ERRBUF_SIZE];
+    libnet_t *netcontext = NULL;
+
     /* misc */
     int c;                      
     char *device = NULL;
@@ -58,6 +67,24 @@ int main(int argc, char **argv)
 
     printf("done\n");
 
+    /*
+     * Memory initialization
+     */
+    printf("Initializing libnet context...");
+    netcontext = libnet_init(LIBNET_RAW4, device, neterr);
+    if (!netcontext){
+        fprintf(stderr,neterr);
+        exit(1);
+    }
+    libnet_clear_packet(netcontext);
+    if (!ip_src_str)
+    {
+        ip_src = libnet_get_ipaddr4(netcontext);
+        ip_src_str = libnet_addr2name4(ip_src, LIBNET_DONT_RESOLVE);
+    }
+
+    printf("done\n");
+
     return 0;
 }