From 7d8a6199730a2fd0cd2a7cfa4fdb73b8399f110a Mon Sep 17 00:00:00 2001
From: Shufeng Cao <caoshufeng@huawei.com>
Date: Tue, 27 Nov 2018 15:03:59 +0800
Subject: [PATCH 1/2] allow binding mac address with ipv6

This change introduces a new option --bind-mac-with-ip6, when this
option is enabled, a client of same mac address will always get the
bound ipv6 address, even when it's duid has been changed.
---
 src/dnsmasq.c |  1 +
 src/dnsmasq.h |  4 +++-
 src/option.c  |  3 +++
 src/rfc3315.c | 34 +++++++++++++++++++++++++++++++++-
 4 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/src/dnsmasq.c b/src/dnsmasq.c
index 9f6c020..32a4d22 100644
--- a/src/dnsmasq.c
+++ b/src/dnsmasq.c
@@ -243,6 +243,7 @@ int main (int argc, char **argv)
   if (daemon->dhcp6)
     {
       daemon->doing_ra = option_bool(OPT_RA);
+      daemon->bind_mac_with_ip6 = option_bool(OPT_BIND_MAC_IP6);
       
       for (context = daemon->dhcp6; context; context = context->next)
 	{
diff --git a/src/dnsmasq.h b/src/dnsmasq.h
index 6773b69..8b31d42 100644
--- a/src/dnsmasq.h
+++ b/src/dnsmasq.h
@@ -269,7 +269,8 @@ struct event_desc {
 #define OPT_IGNORE_CLID    59
 #define OPT_SINGLE_PORT    60
 #define OPT_LEASE_RENEW    61
-#define OPT_LAST           62
+#define OPT_BIND_MAC_IP6   62
+#define OPT_LAST           63

 #define OPTION_BITS (sizeof(unsigned int)*8)
 #define OPTION_SIZE ( (OPT_LAST/OPTION_BITS)+((OPT_LAST%OPTION_BITS)!=0) )
@@ -1049,6 +1050,7 @@ extern struct daemon {
   int override;
   int enable_pxe;
   int doing_ra, doing_dhcp6;
+  int bind_mac_with_ip6;
   struct dhcp_netid_list *dhcp_ignore, *dhcp_ignore_names, *dhcp_gen_names; 
   struct dhcp_netid_list *force_broadcast, *bootp_dynamic;
   struct hostsfile *dhcp_hosts_file, *dhcp_opts_file, *dynamic_dirs;
diff --git a/src/option.c b/src/option.c
index d358d99..919e5a3 100644
--- a/src/option.c
+++ b/src/option.c
@@ -167,7 +167,8 @@ struct myoption {
 #define LOPT_IGNORE_CLID   358
 #define LOPT_SINGLE_PORT   359
 #define LOPT_SCRIPT_TIME   360
- 
+#define LOPT_BIND_MAC_IP6  361
+
 #ifdef HAVE_GETOPT_LONG
 static const struct option opts[] =  
 #else
@@ -339,6 +340,7 @@ static const struct myoption opts[] =
     { "dumpfile", 1, 0, LOPT_DUMPFILE },
     { "dumpmask", 1, 0, LOPT_DUMPMASK },
     { "dhcp-ignore-clid", 0, 0,  LOPT_IGNORE_CLID },
+    { "bind-mac-with-ip6", 0, 0 , LOPT_BIND_MAC_IP6 },
     { NULL, 0, 0, 0 }
   };
 
@@ -518,6 +520,7 @@ static struct {
   { LOPT_DUMPFILE, ARG_ONE, "<path>", gettext_noop("Path to debug packet dump file"), NULL },
   { LOPT_DUMPMASK, ARG_ONE, "<hex>", gettext_noop("Mask which packets to dump"), NULL },
   { LOPT_SCRIPT_TIME, OPT_LEASE_RENEW, NULL, gettext_noop("Call dhcp-script when lease expiry changes."), NULL },
+  { LOPT_BIND_MAC_IP6, OPT_BIND_MAC_IP6, NULL, gettext_noop("Bind mac with ipv6 address. This is an experimental feature and it conflicts with rfc3315."), NULL },
   { 0, 0, NULL, NULL, NULL }
 }; 
 
diff --git a/src/rfc3315.c b/src/rfc3315.c
index 21fcd9b..defd966 100644
--- a/src/rfc3315.c
+++ b/src/rfc3315.c
@@ -49,6 +49,7 @@ static void end_ia(int t1cntr, unsigned int min_time, int do_fuzz);
 static void mark_context_used(struct state *state, struct in6_addr *addr);
 static void mark_config_used(struct dhcp_context *context, struct in6_addr *addr);
 static int check_address(struct state *state, struct in6_addr *addr);
+static int check_and_try_preempte_address(struct state *state, struct in6_addr *addr, time_t now, struct dhcp_config *config);
 static int config_valid(struct dhcp_config *config, struct dhcp_context *context, struct in6_addr *addr, struct state *state, time_t now);
 static struct addrlist *config_implies(struct dhcp_config *config, struct dhcp_context *context, struct in6_addr *addr);
 static void add_address(struct state *state, struct dhcp_context *context, unsigned int lease_time, void *ia_option, 
@@ -703,7 +704,8 @@ static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_
 	    for (c = state->context; c; c = c->current) 
 	      if (!(c->flags & CONTEXT_CONF_USED) &&
 		  match_netid(c->filter, solicit_tags, plain_range) &&
-		  config_valid(config, c, &addr, state, now))
+		  config_valid(config, c, &addr, state, now) &&
+		  check_and_try_preempte_address(state, &addr, now, config))
 		{
 		  mark_config_used(state->context, &addr);
 		  if (have_config(config, CONFIG_TIME))
@@ -1259,6 +1261,37 @@ static int dhcp6_no_relay(struct state *state, int msg_type, void *inbuff, size_
 
 }
 
+static int check_and_try_preempte_address(struct state *state, struct in6_addr *addr, time_t now, struct dhcp_config *config)
+{
+  struct dhcp_lease *lease;
+
+  if (!(lease = lease6_find_by_addr(addr, 128, 0)))
+  {
+    return 1;
+  }
+
+
+  if(daemon->bind_mac_with_ip6) {
+    // break rfc3315 here
+    // bind mac address with a lease
+    if ((state->mac) && !(config->flags & CONFIG_CLID) &&
+      config_has_mac(config, state->mac, state->mac_len, state->mac_type)) {
+      lease_prune(lease, now);
+      return 1;
+    }
+  }
+
+  // what rfc3315 do
+  if (lease->clid_len != state->clid_len ||
+      memcmp(lease->clid, state->clid, state->clid_len) != 0 ||
+      lease->iaid != state->iaid)
+   {
+   return 0;
+   }
+
+  return 1;
+}
+
 static struct dhcp_netid *add_options(struct state *state, int do_refresh)  
 {
   void *oro;
-- 
2.19.1