Give names to the various types of sub-TLV

message.c

@@ -127,7 +127,7 @@ parse_route_attributes(const unsigned char *a, int alen,
 
     while(i < alen) {
         type = a[i];
-        if(type == 0) {
+        if(type == SUBTLV_PAD1) {
             i++;
             continue;
         }
@@ -142,9 +142,9 @@ parse_route_attributes(const unsigned char *a, int alen,
             return;
         }
 
-        if(type == 1) {
+        if(type == SUBTLV_PADN) {
             /* Nothing. */
-        } else if(type == 2) {
+        } else if(type == SUBTLV_DIVERSITY) {
             if(len > DIVERSITY_HOPS) {
                 fprintf(stderr,
                         "Received overlong channel information (%d > %d).\n",

message.h

@@ -25,6 +25,9 @@ THE SOFTWARE.
 #define BUCKET_TOKENS_MAX 200
 #define BUCKET_TOKENS_PER_SEC 40
 
+/* A registry of assigned TLV and sub-TLV types is available at
+   http://www.pps.univ-paris-diderot.fr/~jch/software/babel/babel-tlv-registry.text
+*/
 #define MESSAGE_PAD1 0
 #define MESSAGE_PADN 1
 #define MESSAGE_ACK_REQ 2
@@ -37,6 +40,10 @@ THE SOFTWARE.
 #define MESSAGE_REQUEST 9
 #define MESSAGE_MH_REQUEST 10
 
+/* Protocol extension through sub-TLVs. */
+#define SUBTLV_PAD1 0
+#define SUBTLV_PADN 1
+#define SUBTLV_DIVERSITY 2 /* Also known as babelz. */
 
 extern unsigned short myseqno;
 extern struct timeval seqno_time;