Add a condition for sending timestamps on Hello and IHU

Note that this commit is a no-op, since this condition is true by
default, and it cannot be set in the configuration yet.

interface.c

@@ -305,6 +305,9 @@ interface_up(struct interface *ifp, int up)
             IF_CONF(ifp, update_interval) :
            ifp->hello_interval * 4;
 
+        ifp->enable_timestamps =
+            (IF_CONF(ifp, enable_timestamps) == CONFIG_NO) ? 0 : 1;
+
         ifp->rtt_exponential_decay =
             IF_CONF(ifp, rtt_exponential_decay) > 0 ?
             IF_CONF(ifp, rtt_exponential_decay) : 42;

interface.h

@@ -37,6 +37,7 @@ struct interface_conf {
     char lq;
     char faraway;
     int channel;
+    int enable_timestamps;
     unsigned int rtt_exponential_decay;
     unsigned int rtt_min;
     unsigned int rtt_max;
@@ -95,6 +96,7 @@ struct interface {
     unsigned short hello_seqno;
     unsigned hello_interval;
     unsigned update_interval;
+    int enable_timestamps;
     /* A higher value means we forget old RTT samples faster. Must be
        between 1 and 256, inclusive. */
     unsigned int rtt_exponential_decay;

message.c

@@ -654,7 +654,7 @@ check_bucket(struct interface *ifp)
 static int
 fill_rtt_message(struct interface *ifp)
 {
-    if(ifp->buffered_hello >= 0) {
+    if(ifp->enable_timestamps && (ifp->buffered_hello >= 0)) {
         unsigned int time;
         /* Change the type of sub-TLV. */
         ifp->sendbuf[ifp->buffered_hello + 8] = SUBTLV_TIMESTAMP;
@@ -885,17 +885,19 @@ send_hello_noupdate(struct interface *ifp, unsigned interval)
     debugf("Sending hello %d (%d) to %s.\n",
            ifp->hello_seqno, interval, ifp->name);
 
-    start_message(ifp, MESSAGE_HELLO, 12);
+    start_message(ifp, MESSAGE_HELLO, ifp->enable_timestamps ? 12 : 6);
     ifp->buffered_hello = ifp->buffered - 2;
     accumulate_short(ifp, 0);
     accumulate_short(ifp, ifp->hello_seqno);
     accumulate_short(ifp, interval > 0xFFFF ? 0xFFFF : interval);
-    /* Sub-TLV containing the local time of emission. We use a Pad4
-       sub-TLV, which we'll fill just before sending. */
+    if(ifp->enable_timestamps) {
+        /* Sub-TLV containing the local time of emission. We use a
+           Pad4 sub-TLV, which we'll fill just before sending. */
         accumulate_byte(ifp, SUBTLV_PADN);
         accumulate_byte(ifp, 4);
         accumulate_int(ifp, 0);
-    end_message(ifp, MESSAGE_HELLO, 12);
+    }
+    end_message(ifp, MESSAGE_HELLO, ifp->enable_timestamps ? 12 : 6);
 }
 
 void
@@ -1418,8 +1420,8 @@ send_ihu(struct neighbour *neigh, struct interface *ifp)
 
     ll = linklocal(neigh->address);
 
+    if(ifp->enable_timestamps && neigh->hello_send_us
        /* Checks whether the RTT data is not too old to be sent. */
-    if(neigh->hello_send_us
        && timeval_minus_msec(&now, &neigh->hello_rtt_receive_time) < 1000000) {
         send_rtt_data = 1;
     } else {