Use timeval usecs instead of secs for greater randomistation.

diff --git a/client.c b/client.c
index a82c11146c22d686de7b61f85a898d453f7a3906..28d53a5cf41199257ab6a5532b291929bda53e0a 100644 (file)
--- a/client.c
+++ b/client.c
@@ -80,9 +80,9 @@
 #define T1                     0.5
 #define T2                     0.875
 #define DHCP_BASE              4
+#define DHCP_MAX               64
 #define DHCP_RAND_MIN          -1
 #define DHCP_RAND_MAX          1
-#define DHCP_MAX               64
 
 /* We should define a maximum for the NAK exponential backoff */ 
 #define NAKOFF_MAX              60
@@ -102,6 +102,16 @@
 #define RATE_LIMIT_INTERVAL    60
 #define DEFEND_INTERVAL                10
 
+
+/* number of usecs in a second. */
+#define USECS_SECOND           1000000
+/* As we use timevals, we should use the usec part for
+ * greater randomisation. */
+#define DHCP_RAND_MIN_U                DHCP_RAND_MIN * USECS_SECOND
+#define DHCP_RAND_MAX_U                DHCP_RAND_MAX * USECS_SECOND
+#define PROBE_MIN_U            PROBE_MIN * USECS_SECOND
+#define PROBE_MAX_U            PROBE_MAX * USECS_SECOND
+
 struct if_state {
        int options;
        struct interface *interface;
@@ -1070,8 +1080,9 @@ handle_timeout(struct if_state *state, const struct options *options)
                        logger(LOG_DEBUG, "sending ARP probe #%d",
                               state->probes);
                        if (state->probes < PROBE_NUM) 
-                               tv.tv_sec = (arc4random() %
-                                            (PROBE_MAX - PROBE_MIN)) + PROBE_MIN;
+                               tv.tv_usec = (arc4random() %
+                                             (PROBE_MAX_U - PROBE_MIN_U)) +
+                                            PROBE_MIN_U;
                        else
                                tv.tv_sec = ANNOUNCE_WAIT;
                        get_time(&state->timeout);
@@ -1207,8 +1218,8 @@ handle_timeout(struct if_state *state, const struct options *options)
                        break;
                }
        }
-       tv.tv_sec += (arc4random() % (DHCP_RAND_MAX - DHCP_RAND_MIN)) +
-               DHCP_RAND_MIN;
+       tv.tv_usec += (arc4random() % (DHCP_RAND_MAX_U - DHCP_RAND_MIN_U)) +
+               DHCP_RAND_MIN_U;
        timeradd(&state->timeout, &tv, &state->timeout);
        return 0;
 }