From 3511a928691cda102d4cb395309ba46ae5920be8 Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Thu, 7 Nov 2013 10:28:11 +0000
Subject: [PATCH] Fix start-up order for making DHCPv6 DUID

Previously, if the DUID wasn't read from the lease-file or
script, a new one was created _after_ the helper process fork,
so for that first run, the script calls got an empty DUID.

Also, use a DUID_LL format DUID when there's no stable lease
storage, as well as when the RTC is broken. That has a chance of
evaluating to the same value on each startup.
---
 src/dhcp6.c   | 42 +++++++++++++++++++++++++++---------------
 src/dnsmasq.c |  3 +++
 src/dnsmasq.h |  1 +
 src/lease.c   | 10 ++++++++--
 4 files changed, 39 insertions(+), 17 deletions(-)

diff --git a/src/dhcp6.c b/src/dhcp6.c
index 7b0adcf..7c72872 100644
--- a/src/dhcp6.c
+++ b/src/dhcp6.c
@@ -523,6 +523,8 @@ int config_valid(struct dhcp_config *config, struct dhcp_context *context, struc
 
 void make_duid(time_t now)
 {
+  (void)now;
+
   if (daemon->duid_config)
     {
       unsigned char *p;
@@ -535,8 +537,14 @@ void make_duid(time_t now)
     }
   else
     {
+      time_t newnow = 0;
+      
+      /* If we have no persistent lease database, or a non-stable RTC, use DUID_LL (newnow == 0) */
+#ifndef HAVE_BROKEN_RTC
       /* rebase epoch to 1/1/2000 */
-      time_t newnow = now - 946684800;
+      if (!option_bool(OPT_LEASE_RO) || daemon->lease_change_command)
+	newnow = now - 946684800;
+#endif      
       
       iface_enumerate(AF_LOCAL, &newnow, make_duid1);
       
@@ -555,23 +563,27 @@ static int make_duid1(int index, unsigned int type, char *mac, size_t maclen, vo
   unsigned char *p;
   (void)index;
   (void)parm;
-
+  time_t newnow = *((time_t *)parm);
+  
   if (type >= 256)
     return 1;
 
-#ifdef HAVE_BROKEN_RTC
-  daemon->duid = p = safe_malloc(maclen + 4);
-  daemon->duid_len = maclen + 4;
-  PUTSHORT(3, p); /* DUID_LL */
-  PUTSHORT(type, p); /* address type */
-#else
-  daemon->duid = p = safe_malloc(maclen + 8);
-  daemon->duid_len = maclen + 8;
-  PUTSHORT(1, p); /* DUID_LLT */
-  PUTSHORT(type, p); /* address type */
-  PUTLONG(*((time_t *)parm), p); /* time */
-#endif
-
+  if (newnow == 0)
+    {
+      daemon->duid = p = safe_malloc(maclen + 4);
+      daemon->duid_len = maclen + 4;
+      PUTSHORT(3, p); /* DUID_LL */
+      PUTSHORT(type, p); /* address type */
+    }
+  else
+    {
+      daemon->duid = p = safe_malloc(maclen + 8);
+      daemon->duid_len = maclen + 8;
+      PUTSHORT(1, p); /* DUID_LLT */
+      PUTSHORT(type, p); /* address type */
+      PUTLONG(*((time_t *)parm), p); /* time */
+    }
+  
   memcpy(p, mac, maclen);
 
   return 0;
diff --git a/src/dnsmasq.c b/src/dnsmasq.c
index a2b37dc..a701ab5 100644
--- a/src/dnsmasq.c
+++ b/src/dnsmasq.c
@@ -273,6 +273,9 @@ int main (int argc, char **argv)
   /* after enumerate_interfaces() */
   if (daemon->doing_dhcp6 || daemon->relay6 || daemon->doing_ra)
     join_multicast(1);
+
+  /* After netlink_init() and before create_helper() */
+  lease_make_duid(now);
 #endif
   
   if (daemon->port != 0)
diff --git a/src/dnsmasq.h b/src/dnsmasq.h
index 4d368c5..62b1d68 100644
--- a/src/dnsmasq.h
+++ b/src/dnsmasq.h
@@ -1120,6 +1120,7 @@ u64 lease_find_max_addr6(struct dhcp_context *context);
 void lease_ping_reply(struct in6_addr *sender, unsigned char *packet, char *interface);
 void lease_update_slaac(time_t now);
 void lease_set_iaid(struct dhcp_lease *lease, int iaid);
+void lease_make_duid(time_t now);
 #endif
 void lease_set_hwaddr(struct dhcp_lease *lease, unsigned char *hwaddr,
 		      unsigned char *clid, int hw_len, int hw_type, int clid_len, time_t now, int force);
diff --git a/src/lease.c b/src/lease.c
index 4b4d10a..7e00804 100644
--- a/src/lease.c
+++ b/src/lease.c
@@ -417,15 +417,21 @@ void lease_find_interfaces(time_t now)
   iface_enumerate(AF_INET, &now, find_interface_v4);
 #ifdef HAVE_DHCP6
   iface_enumerate(AF_INET6, &now, find_interface_v6);
+#endif
+}
 
+#ifdef HAVE_DHCP6
+void lease_make_duid(time_t now)
+{
   /* If we're not doing DHCPv6, and there are not v6 leases, don't add the DUID to the database */
-  if (!daemon->duid && daemon->dhcp6)
+  if (!daemon->duid && daemon->doing_dhcp6)
     {
       file_dirty = 1;
       make_duid(now);
     }
-#endif
 }
+#endif
+