Implement hash_id.

message.c

@@ -58,6 +58,16 @@ struct buffered_update buffered_updates[MAX_BUFFERED_UPDATES];
 struct network *update_net = NULL;
 int updates = 0;
 
+unsigned short
+hash_id(const unsigned char *id)
+{
+    int i;
+    unsigned short hash = 0;
+    for(i = 0; i < 8; i++)
+        hash ^= (id[2 * i] << 8) | id[2 * i + 1];
+    return hash;
+}
+
 void
 parse_packet(const unsigned char *from, struct network *net,
              const unsigned char *packet, int len)

message.h

@@ -35,6 +35,7 @@ extern int split_horizon;
 extern struct timeval update_flush_time;
 extern const unsigned char packet_header[8];
 
+unsigned short hash_id(const unsigned char *id) ATTRIBUTE ((pure));
 void parse_packet(const unsigned char *from, struct network *net,
                   const unsigned char *packet, int len);
 void flushbuf(struct network *net);