fix DUID-LTT epoch

RELNOTES

@@ -156,6 +156,9 @@ work on other platforms. Please report any problems and suggested fixes to
 - Fix startup error messages to report a missing "subnet6 declaration", rather
   than a missing "subnet declaration", when running as a DHCPv6 server.
 
+- DHCPv6 client timestamp in DUID was based on the year 1970 rather 
+  than the year 2000.
+
 			Changes since 4.0.0b3
 
 - The reverse dns name for PTR updates on IPv6 addresses has been fixed to

client/dhc6.c

@@ -135,7 +135,7 @@ form_duid(struct data_string *duid, const char *file, int line)
 	/* Basic Link Local Address type of DUID. */
 	putUShort(duid->buffer->data, DUID_LLT);
 	putUShort(duid->buffer->data + 2, ip->hw_address.hbuf[0]);
-	putULong(duid->buffer->data + 4, cur_time);
+	putULong(duid->buffer->data + 4, cur_time - DUID_TIME_EPOCH);
 	memcpy(duid->buffer->data + 8, ip->hw_address.hbuf + 1,
 	       ip->hw_address.hlen - 1);
 }

includes/dhcp6.h

@@ -195,3 +195,10 @@ struct dhcpv6_relay_packet {
 
 #define LQ6QT_BY_ADDRESS	1
 #define LQ6QT_BY_CLIENTID	2
+
+/*
+ * DUID time starts 2000-01-01.
+ * This constant is the number of seconds since 1970-01-01,
+ * when the Unix epoch began.
+ */
+#define DUID_TIME_EPOCH 946684800

server/dhcpv6.c

@@ -112,13 +112,6 @@ static isc_result_t reply_process_send_addr(struct reply_state *reply,
 					    struct iaddr *addr);
 static struct iaaddr *lease_compare(struct iaaddr *alpha, struct iaaddr *beta);
 
-/*
- * DUID time starts 2000-01-01.
- * This constant is the number of seconds since 1970-01-01,
- * when the Unix epoch began.
- */
-#define DUID_TIME_EPOCH 946684800
-
 /*
  * This function returns the time since DUID time start for the
  * given time_t value.