From d81b42d0674d161934a060bea5de1a44a8238376 Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Mon, 23 Sep 2013 12:26:34 +0100
Subject: [PATCH] Prod neighbour  discovery with ARP instead of PING.

---
 src/dhcp6.c         | 17 +++++++++--------
 src/radv-protocol.h |  7 +++++++
 src/rfc3315.c       | 34 ++++++++++++++++------------------
 3 files changed, 32 insertions(+), 26 deletions(-)

diff --git a/src/dhcp6.c b/src/dhcp6.c
index 9ad8912..5e151d6 100644
--- a/src/dhcp6.c
+++ b/src/dhcp6.c
@@ -183,13 +183,13 @@ void dhcp6_packet(time_t now)
 	return;
 
       /* Recieving a packet from a host does not populate the neighbour
-	 cache, so we send a ping to prompt neighbour discovery if we can't 
+	 cache, so we send a neighbour discovery request if we can't 
 	 find the sender. Repeat a few times in case of packet loss. */
       
       for (i = 0; i < 5; i++)
 	{
 	  struct timespec ts;
-	  struct ping_packet *ping;
+	  struct neigh_packet *neigh;
 	  struct sockaddr_in6 addr;
 	  
 	  mac_param.target = &from.sin6_addr;
@@ -201,12 +201,12 @@ void dhcp6_packet(time_t now)
 	    break;
 	 
 	  save_counter(0);
-	  ping = expand(sizeof(struct ping_packet));
-	  ping->type = ICMP6_ECHO_REQUEST;
-	  ping->code = 0;
-	  ping->identifier = 1;
-	  ping->sequence_no = 1;
-            
+	  neigh = expand(sizeof(struct neigh_packet));
+	  neigh->type = ND_NEIGHBOR_SOLICIT;
+	  neigh->code = 0;
+	  neigh->reserved = 0;
+	  neigh->target = from.sin6_addr;
+
 	  memset(&addr, 0, sizeof(addr));
 #ifdef HAVE_SOCKADDR_SA_LEN
 	  addr.sin6_len = sizeof(struct sockaddr_in6);
@@ -214,6 +214,7 @@ void dhcp6_packet(time_t now)
 	  addr.sin6_family = AF_INET6;
 	  addr.sin6_port = htons(IPPROTO_ICMPV6);
 	  addr.sin6_addr = from.sin6_addr;
+	  addr.sin6_scope_id = from.sin6_scope_id;
           
 	  sendto(daemon->icmp6fd, daemon->outpacket.iov_base, save_counter(0), 0,
 		 (struct sockaddr *)&addr,  sizeof(addr));
diff --git a/src/radv-protocol.h b/src/radv-protocol.h
index 1f0f88a..8d5b153 100644
--- a/src/radv-protocol.h
+++ b/src/radv-protocol.h
@@ -33,6 +33,13 @@ struct ra_packet {
   u32 retrans_time;
 };
 
+struct neigh_packet {
+  u8 type, code;
+  u16 checksum;
+  u16 reserved;
+  struct in6_addr target;
+};
+
 struct prefix_opt {
   u8 type, len, prefix_len, flags;
   u32 valid_lifetime, preferred_lifetime, reserved;
diff --git a/src/rfc3315.c b/src/rfc3315.c
index ee06353..26dca71 100644
--- a/src/rfc3315.c
+++ b/src/rfc3315.c
@@ -419,14 +419,22 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
     }
 
   if (mac_len != 0)
-    for (mac_opt = daemon->dhcp_macs; mac_opt; mac_opt = mac_opt->next)
-      if ((unsigned)mac_opt->hwaddr_len == mac_len &&
-	  ((unsigned)mac_opt->hwaddr_type == mac_type || mac_opt->hwaddr_type == 0) &&
-	  memcmp_masked(mac_opt->hwaddr, mac, mac_len, mac_opt->mask))
+    {
+      if (option_bool(OPT_LOG_OPTS))
 	{
-	  mac_opt->netid.next = state.tags;
-	  state.tags = &mac_opt->netid;
+	  print_mac(daemon->dhcp_buff, mac, mac_len);
+	  my_syslog(MS_DHCP | LOG_INFO, _("%u client MAC address: %s"), state.xid, daemon->dhcp_buff);
 	}
+
+      for (mac_opt = daemon->dhcp_macs; mac_opt; mac_opt = mac_opt->next)
+	if ((unsigned)mac_opt->hwaddr_len == mac_len &&
+	    ((unsigned)mac_opt->hwaddr_type == mac_type || mac_opt->hwaddr_type == 0) &&
+	    memcmp_masked(mac_opt->hwaddr, mac, mac_len, mac_opt->mask))
+	  {
+	    mac_opt->netid.next = state.tags;
+	    state.tags = &mac_opt->netid;
+	  }
+    }
   
   if ((opt = opt6_find(state.packet_options, state.end, OPTION6_FQDN, 1)))
     {
@@ -1225,18 +1233,8 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
     }
   
   log_tags(tagif, state.xid);
+  log6_opts(0, state.xid, daemon->outpacket.iov_base + start_opts, daemon->outpacket.iov_base + save_counter(-1));
   
-  if (option_bool(OPT_LOG_OPTS))
-    {
-      if (mac_len != 0)
-	{
-	  print_mac(daemon->dhcp_buff, mac, mac_len);
-	  my_syslog(MS_DHCP | LOG_INFO, _("%u client MAC address: %s"), state.xid, daemon->dhcp_buff);
-	}
-      
-      log6_opts(0, state.xid, daemon->outpacket.iov_base + start_opts, daemon->outpacket.iov_base + save_counter(-1));
-    }
-
   return 1;
 
 }
@@ -1824,7 +1822,7 @@ static void log6_opts(int nest, unsigned int xid, void *start_opts, void *end_op
   void *opt;
   char *desc = nest ? "nest" : "sent";
   
-  if (start_opts == end_opts)
+  if (!option_bool(OPT_LOG_OPTS) || start_opts == end_opts)
     return;
   
   for (opt = start_opts; opt; opt = opt6_next(opt, end_opts))