fixed DHCPv6 options processing

dhcp_protect.c

@@ -253,6 +253,8 @@ int dp_dhcp_check(struct nfq_data *nfa, dp_conf *conf) {
 		}
 	}
 
+	if ( conf->debug ) printf("remoteidlen=%i\n",remoteidlen);
+
 	if ( remoteidlen>0 ) {
 		if ( conf->debug ) {
 			int i;
@@ -283,43 +285,45 @@ int dp_dhcp_check(struct nfq_data *nfa, dp_conf *conf) {
 }
 
 void dp_dhcpv6_check(dp_conf *conf, unsigned char *pkt, int pktlen, int offset, unsigned char **remoteid, int *remoteidlen) {
+	uint8_t msgtype = (uint8_t)pkt[offset];
 
-	while(offset<pktlen) {
-		uint8_t msgtype = (uint8_t)pkt[offset];
+	if ( conf->debug ) printf("offset=%i\n",offset);
 
-		switch(msgtype) {
-			case 11: // RELAY-FORW
-			case 12: // RELAY-REPL
-				offset += 2 + 16 + 16; // msg-type, hop-count, link-addr, peer-addr
-				break;
-			default: // all other msgtypes
-				offset += 2; // msg-type, hop-count
-		}
+	switch(msgtype) {
+		case 12: // RELAY-FORW
+		case 13: // RELAY-REPL
+			offset += 2 + 16 + 16; // msg-type, hop-count, link-addr, peer-addr
+			if ( conf->debug ) printf("this is a relay msg\n");
+			break;
+		default: // all other msgtypes
+			offset += 2; // msg-type, hop-count
+	}
 
-		while(offset+4<=pktlen) {
-			uint16_t code = ntohs((uint16_t)pkt[offset]);
-			uint16_t len  = ntohs((uint16_t)pkt[offset+2]);
+	if ( conf->debug ) printf("offset=%i\n",offset);
 
-			offset+=4;
+	while(offset+4<=pktlen) {
+		uint16_t code = ntohs(*(uint16_t*)(pkt+offset));
+		uint16_t len  = ntohs(*(uint16_t*)(pkt+offset+2));
 
-			if ( code == 9 ) { // relay message
-				offset += 4;
-				continue;
-			}
+		if ( conf->debug ) printf("code %i len %i\n", code, len);
 
-			if ( code == 1 ) { // Client identifier / DUID
-				// make sure there's enough space
-				if ( offset + len <= pktlen ) {
-					*remoteid = pkt+offset;
-					*remoteidlen = len;
-					break;
-				}
-			}
-			offset+=len;
+		offset+=4;
+
+		if ( code == 9 ) { // relay message
+			if ( conf->debug ) printf("option 9, relay msg\n");
+			offset+=4;
+			continue;
 		}
 
-		if ( *remoteidlen>0 )
-			break;
+		if ( code == 1 ) { // Client identifier / DUID
+			// make sure there's enough space
+			if ( offset + len <= pktlen ) {
+				*remoteid = pkt+offset;
+				*remoteidlen = len;
+				break;
+			}
+		}
+		offset+=len;
 	}
 }