[T106][ZXW-22]7520V3SCV2.01.01.02P42U09_VEC_V0.8_AP_VEC origin source commit

Change-Id: Ic6e05d89ecd62fc34f82b23dcf306c93764aec4b
diff --git a/ap/app/dnsmasq/dnsmasq-2.86/src/dhcp6.c b/ap/app/dnsmasq/dnsmasq-2.86/src/dhcp6.c
new file mode 100755
index 0000000..2be877f
--- /dev/null
+++ b/ap/app/dnsmasq/dnsmasq-2.86/src/dhcp6.c
@@ -0,0 +1,828 @@
+/* dnsmasq is Copyright (c) 2000-2021 Simon Kelley
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 dated June, 1991, or
+   (at your option) version 3 dated 29 June, 2007.
+ 
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+     
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "dnsmasq.h"
+
+#ifdef HAVE_DHCP6
+
+#include <netinet/icmp6.h>
+
+struct iface_param {
+  struct dhcp_context *current;
+  struct dhcp_relay *relay;
+  struct in6_addr fallback, relay_local, ll_addr, ula_addr;
+  int ind, addr_match;
+};
+
+
+static int complete_context6(struct in6_addr *local,  int prefix,
+			     int scope, int if_index, int flags, 
+			     unsigned int preferred, unsigned int valid, void *vparam);
+static int make_duid1(int index, unsigned int type, char *mac, size_t maclen, void *parm); 
+
+void dhcp6_init(void)
+{
+  int fd;
+  struct sockaddr_in6 saddr;
+#if defined(IPV6_TCLASS) && defined(IPTOS_CLASS_CS6)
+  int class = IPTOS_CLASS_CS6;
+#endif
+  int oneopt = 1;
+
+  if ((fd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP)) == -1 ||
+#if defined(IPV6_TCLASS) && defined(IPTOS_CLASS_CS6)
+      setsockopt(fd, IPPROTO_IPV6, IPV6_TCLASS, &class, sizeof(class)) == -1 ||
+#endif
+      setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &oneopt, sizeof(oneopt)) == -1 ||
+      !fix_fd(fd) ||
+      !set_ipv6pktinfo(fd))
+    die (_("cannot create DHCPv6 socket: %s"), NULL, EC_BADNET);
+  
+ /* When bind-interfaces is set, there might be more than one dnsmasq
+     instance binding port 547. That's OK if they serve different networks.
+     Need to set REUSEADDR|REUSEPORT to make this possible.
+     Handle the case that REUSEPORT is defined, but the kernel doesn't 
+     support it. This handles the introduction of REUSEPORT on Linux. */
+  if (option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND))
+    {
+      int rc = 0;
+
+#ifdef SO_REUSEPORT
+      if ((rc = setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &oneopt, sizeof(oneopt))) == -1 &&
+	  errno == ENOPROTOOPT)
+	rc = 0;
+#endif
+      
+      if (rc != -1)
+	rc = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &oneopt, sizeof(oneopt));
+      
+      if (rc == -1)
+	die(_("failed to set SO_REUSE{ADDR|PORT} on DHCPv6 socket: %s"), NULL, EC_BADNET);
+    }
+  
+  memset(&saddr, 0, sizeof(saddr));
+#ifdef HAVE_SOCKADDR_SA_LEN
+  saddr.sin6_len = sizeof(struct sockaddr_in6);
+#endif
+  saddr.sin6_family = AF_INET6;
+  saddr.sin6_addr = in6addr_any;
+  saddr.sin6_port = htons(DHCPV6_SERVER_PORT);
+  
+  if (bind(fd, (struct sockaddr *)&saddr, sizeof(struct sockaddr_in6)))
+    die(_("failed to bind DHCPv6 server socket: %s"), NULL, EC_BADNET);
+  
+  daemon->dhcp6fd = fd;
+}
+
+void dhcp6_packet(time_t now)
+{
+  struct dhcp_context *context;
+  struct dhcp_relay *relay;
+  struct iface_param parm;
+  struct cmsghdr *cmptr;
+  struct msghdr msg;
+  int if_index = 0;
+  union {
+    struct cmsghdr align; /* this ensures alignment */
+    char control6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
+  } control_u;
+  struct sockaddr_in6 from;
+  ssize_t sz; 
+  struct ifreq ifr;
+  struct iname *tmp;
+  unsigned short port;
+  struct in6_addr dst_addr;
+
+  memset(&dst_addr, 0, sizeof(dst_addr));
+
+  msg.msg_control = control_u.control6;
+  msg.msg_controllen = sizeof(control_u);
+  msg.msg_flags = 0;
+  msg.msg_name = &from;
+  msg.msg_namelen = sizeof(from);
+  msg.msg_iov =  &daemon->dhcp_packet;
+  msg.msg_iovlen = 1;
+  
+  if ((sz = recv_dhcp_packet(daemon->dhcp6fd, &msg)) == -1)
+    return;
+  
+  for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr))
+    if (cmptr->cmsg_level == IPPROTO_IPV6 && cmptr->cmsg_type == daemon->v6pktinfo)
+      {
+	union {
+	  unsigned char *c;
+	  struct in6_pktinfo *p;
+	} p;
+	p.c = CMSG_DATA(cmptr);
+        
+	if_index = p.p->ipi6_ifindex;
+	dst_addr = p.p->ipi6_addr;
+      }
+
+  if (!indextoname(daemon->dhcp6fd, if_index, ifr.ifr_name))
+    return;
+
+  if ((port = relay_reply6(&from, sz, ifr.ifr_name)) != 0)
+    {
+      from.sin6_port = htons(port);
+      while (retry_send(sendto(daemon->dhcp6fd, daemon->outpacket.iov_base, 
+			       save_counter(-1), 0, (struct sockaddr *)&from, 
+			       sizeof(from))));
+    }
+  else
+    {
+      struct dhcp_bridge *bridge, *alias;
+
+      for (tmp = daemon->if_except; tmp; tmp = tmp->next)
+	if (tmp->name && wildcard_match(tmp->name, ifr.ifr_name))
+	  return;
+      
+      for (tmp = daemon->dhcp_except; tmp; tmp = tmp->next)
+	if (tmp->name && wildcard_match(tmp->name, ifr.ifr_name))
+	  return;
+      
+      parm.current = NULL;
+      parm.relay = NULL;
+      memset(&parm.relay_local, 0, IN6ADDRSZ);
+      parm.ind = if_index;
+      parm.addr_match = 0;
+      memset(&parm.fallback, 0, IN6ADDRSZ);
+      memset(&parm.ll_addr, 0, IN6ADDRSZ);
+      memset(&parm.ula_addr, 0, IN6ADDRSZ);
+
+      /* If the interface on which the DHCPv6 request was received is
+         an alias of some other interface (as specified by the
+         --bridge-interface option), change parm.ind so that we look
+         for DHCPv6 contexts associated with the aliased interface
+         instead of with the aliasing one. */
+      for (bridge = daemon->bridges; bridge; bridge = bridge->next)
+	{
+	  for (alias = bridge->alias; alias; alias = alias->next)
+	    if (wildcard_matchn(alias->iface, ifr.ifr_name, IF_NAMESIZE))
+	      {
+		parm.ind = if_nametoindex(bridge->iface);
+		if (!parm.ind)
+		  {
+		    my_syslog(MS_DHCP | LOG_WARNING,
+			      _("unknown interface %s in bridge-interface"),
+			      bridge->iface);
+		    return;
+		  }
+		break;
+	      }
+	  if (alias)
+	    break;
+	}
+      
+      for (context = daemon->dhcp6; context; context = context->next)
+	if (IN6_IS_ADDR_UNSPECIFIED(&context->start6) && context->prefix == 0)
+	  {
+	    /* wildcard context for DHCP-stateless only */
+	    parm.current = context;
+	    context->current = NULL;
+	  }
+	else
+	  {
+	    /* unlinked contexts are marked by context->current == context */
+	    context->current = context;
+	    memset(&context->local6, 0, IN6ADDRSZ);
+	  }
+
+      for (relay = daemon->relay6; relay; relay = relay->next)
+	relay->current = relay;
+      
+      if (!iface_enumerate(AF_INET6, &parm, complete_context6))
+	return;
+
+      if (daemon->if_names || daemon->if_addrs)
+	{
+	  
+	  for (tmp = daemon->if_names; tmp; tmp = tmp->next)
+	    if (tmp->name && wildcard_match(tmp->name, ifr.ifr_name))
+	      break;
+	  
+	  if (!tmp && !parm.addr_match)
+	    return;
+	}
+      
+      if (parm.relay)
+	{
+	  /* Ignore requests sent to the ALL_SERVERS multicast address for relay when
+	     we're listening there for DHCPv6 server reasons. */
+	  struct in6_addr all_servers;
+	  
+	  inet_pton(AF_INET6, ALL_SERVERS, &all_servers);
+	  
+	  if (!IN6_ARE_ADDR_EQUAL(&dst_addr, &all_servers))
+	    relay_upstream6(parm.relay, sz, &from.sin6_addr, from.sin6_scope_id, now);
+	  return;
+	}
+      
+      /* May have configured relay, but not DHCP server */
+      if (!daemon->doing_dhcp6)
+	return;
+
+      lease_prune(NULL, now); /* lose any expired leases */
+      
+      port = dhcp6_reply(parm.current, if_index, ifr.ifr_name, &parm.fallback, 
+			 &parm.ll_addr, &parm.ula_addr, sz, &from.sin6_addr, now);
+      
+      /* The port in the source address of the original request should
+	 be correct, but at least once client sends from the server port,
+	 so we explicitly send to the client port to a client, and the
+	 server port to a relay. */
+      if (port != 0)
+	{
+	  from.sin6_port = htons(port);
+	  while (retry_send(sendto(daemon->dhcp6fd, daemon->outpacket.iov_base, 
+				   save_counter(-1), 0, (struct sockaddr *)&from, 
+				   sizeof(from))));
+	}
+
+      /* These need to be called _after_ we send DHCPv6 packet, since lease_update_file()
+	 may trigger sending an RA packet, which overwrites our buffer. */
+      lease_update_file(now);
+      lease_update_dns(0);
+    }
+}
+
+void get_client_mac(struct in6_addr *client, int iface, unsigned char *mac, unsigned int *maclenp, unsigned int *mactypep, time_t now)
+{
+  /* Receiving a packet from a host does not populate the neighbour
+     cache, so we send a neighbour discovery request if we can't 
+     find the sender. Repeat a few times in case of packet loss. */
+  
+  struct neigh_packet neigh;
+  union mysockaddr addr;
+  int i, maclen;
+
+  neigh.type = ND_NEIGHBOR_SOLICIT;
+  neigh.code = 0;
+  neigh.reserved = 0;
+  neigh.target = *client;
+  /* RFC4443 section-2.3: checksum has to be zero to be calculated */
+  neigh.checksum = 0;
+   
+  memset(&addr, 0, sizeof(addr));
+#ifdef HAVE_SOCKADDR_SA_LEN
+  addr.in6.sin6_len = sizeof(struct sockaddr_in6);
+#endif
+  addr.in6.sin6_family = AF_INET6;
+  addr.in6.sin6_port = htons(IPPROTO_ICMPV6);
+  addr.in6.sin6_addr = *client;
+  addr.in6.sin6_scope_id = iface;
+  
+  for (i = 0; i < 5; i++)
+    {
+      struct timespec ts;
+      
+      if ((maclen = find_mac(&addr, mac, 0, now)) != 0)
+	break;
+	  
+      sendto(daemon->icmp6fd, &neigh, sizeof(neigh), 0, &addr.sa, sizeof(addr));
+      
+      ts.tv_sec = 0;
+      ts.tv_nsec = 100000000; /* 100ms */
+      nanosleep(&ts, NULL);
+    }
+
+  *maclenp = maclen;
+  *mactypep = ARPHRD_ETHER;
+}
+    
+static int complete_context6(struct in6_addr *local,  int prefix,
+			     int scope, int if_index, int flags, unsigned int preferred, 
+			     unsigned int valid, void *vparam)
+{
+  struct dhcp_context *context;
+  struct shared_network *share;
+  struct dhcp_relay *relay;
+  struct iface_param *param = vparam;
+  struct iname *tmp;
+ 
+  (void)scope; /* warning */
+  
+  if (if_index != param->ind)
+    return 1;
+  
+  if (IN6_IS_ADDR_LINKLOCAL(local))
+    param->ll_addr = *local;
+  else if (IN6_IS_ADDR_ULA(local))
+    param->ula_addr = *local;
+      
+  if (IN6_IS_ADDR_LOOPBACK(local) ||
+      IN6_IS_ADDR_LINKLOCAL(local) ||
+      IN6_IS_ADDR_MULTICAST(local))
+    return 1;
+  
+  /* if we have --listen-address config, see if the 
+     arrival interface has a matching address. */
+  for (tmp = daemon->if_addrs; tmp; tmp = tmp->next)
+    if (tmp->addr.sa.sa_family == AF_INET6 &&
+	IN6_ARE_ADDR_EQUAL(&tmp->addr.in6.sin6_addr, local))
+      param->addr_match = 1;
+  
+  /* Determine a globally address on the arrival interface, even
+     if we have no matching dhcp-context, because we're only
+     allocating on remote subnets via relays. This
+     is used as a default for the DNS server option. */
+  param->fallback = *local;
+  
+  for (context = daemon->dhcp6; context; context = context->next)
+    if ((context->flags & CONTEXT_DHCP) &&
+	!(context->flags & (CONTEXT_TEMPLATE | CONTEXT_OLD)) &&
+	prefix <= context->prefix &&
+	context->current == context)
+      {
+	if (is_same_net6(local, &context->start6, context->prefix) &&
+	    is_same_net6(local, &context->end6, context->prefix))
+	  {
+	    struct dhcp_context *tmp, **up;
+	    
+	    /* use interface values only for constructed contexts */
+	    if (!(context->flags & CONTEXT_CONSTRUCTED))
+	      preferred = valid = 0xffffffff;
+	    else if (flags & IFACE_DEPRECATED)
+	      preferred = 0;
+		    
+	    if (context->flags & CONTEXT_DEPRECATE)
+	      preferred = 0;
+	    
+	    /* order chain, longest preferred time first */
+	    for (up = &param->current, tmp = param->current; tmp; tmp = tmp->current)
+	      if (tmp->preferred <= preferred)
+		break;
+	      else
+		up = &tmp->current;
+	    
+	    context->current = *up;
+	    *up = context;
+	    context->local6 = *local;
+	    context->preferred = preferred;
+	    context->valid = valid;
+	  }
+	else
+	  {
+	    for (share = daemon->shared_networks; share; share = share->next)
+	      {
+		/* IPv4 shared_address - ignore */
+		if (share->shared_addr.s_addr != 0)
+		  continue;
+			
+		if (share->if_index != 0)
+		  {
+		    if (share->if_index != if_index)
+		      continue;
+		  }
+		else
+		  {
+		    if (!IN6_ARE_ADDR_EQUAL(&share->match_addr6, local))
+		      continue;
+		  }
+		
+		if (is_same_net6(&share->shared_addr6, &context->start6, context->prefix) &&
+		    is_same_net6(&share->shared_addr6, &context->end6, context->prefix))
+		  {
+		    context->current = param->current;
+		    param->current = context;
+		    context->local6 = *local;
+		    context->preferred = context->flags & CONTEXT_DEPRECATE ? 0 :0xffffffff;
+		    context->valid = 0xffffffff;
+		  }
+	      }
+	  }      
+      }
+
+  for (relay = daemon->relay6; relay; relay = relay->next)
+    if (IN6_ARE_ADDR_EQUAL(local, &relay->local.addr6) && relay->current == relay &&
+	(IN6_IS_ADDR_UNSPECIFIED(&param->relay_local) || IN6_ARE_ADDR_EQUAL(local, &param->relay_local)))
+      {
+	relay->current = param->relay;
+	param->relay = relay;
+	param->relay_local = *local;
+      }
+     
+  return 1;
+}
+
+struct dhcp_config *config_find_by_address6(struct dhcp_config *configs, struct in6_addr *net, int prefix,  struct in6_addr *addr)
+{
+  struct dhcp_config *config;
+  
+  for (config = configs; config; config = config->next)
+    if (config->flags & CONFIG_ADDR6)
+      {
+	struct addrlist *addr_list;
+	
+	for (addr_list = config->addr6; addr_list; addr_list = addr_list->next)
+	  if ((!net || is_same_net6(&addr_list->addr.addr6, net, prefix) || ((addr_list->flags & ADDRLIST_WILDCARD) && prefix == 64)) &&
+	      is_same_net6(&addr_list->addr.addr6, addr, (addr_list->flags & ADDRLIST_PREFIX) ? addr_list->prefixlen : 128))
+	    return config;
+      }
+  
+  return NULL;
+}
+
+struct dhcp_context *address6_allocate(struct dhcp_context *context,  unsigned char *clid, int clid_len, int temp_addr,
+				       unsigned int iaid, int serial, struct dhcp_netid *netids, int plain_range, struct in6_addr *ans)
+{
+  /* Find a free address: exclude anything in use and anything allocated to
+     a particular hwaddr/clientid/hostname in our configuration.
+     Try to return from contexts which match netids first. 
+     
+     Note that we assume the address prefix lengths are 64 or greater, so we can
+     get by with 64 bit arithmetic.
+*/
+
+  u64 start, addr;
+  struct dhcp_context *c, *d;
+  int i, pass;
+  u64 j; 
+
+  /* hash hwaddr: use the SDBM hashing algorithm.  This works
+     for MAC addresses, let's see how it manages with client-ids! 
+     For temporary addresses, we generate a new random one each time. */
+  if (temp_addr)
+    j = rand64();
+  else
+    for (j = iaid, i = 0; i < clid_len; i++)
+      j = clid[i] + (j << 6) + (j << 16) - j;
+  
+  for (pass = 0; pass <= plain_range ? 1 : 0; pass++)
+    for (c = context; c; c = c->current)
+      if (c->flags & (CONTEXT_DEPRECATE | CONTEXT_STATIC | CONTEXT_RA_STATELESS | CONTEXT_USED))
+	continue;
+      else if (!match_netid(c->filter, netids, pass))
+	continue;
+      else
+	{ 
+	  if (!temp_addr && option_bool(OPT_CONSEC_ADDR))
+	    {
+	      /* seed is largest extant lease addr in this context,
+		 skip addresses equal to the number of addresses rejected
+		 by clients. This should avoid the same client being offered the same
+		 address after it has rjected it. */
+	      start = lease_find_max_addr6(c) + 1 + serial + c->addr_epoch;
+	      if (c->addr_epoch)
+		c->addr_epoch--;
+	    }
+	  else
+	    {
+	      u64 range = 1 + addr6part(&c->end6) - addr6part(&c->start6);
+	      u64 offset = j + c->addr_epoch;
+
+	      /* don't divide by zero if range is whole 2^64 */
+	      if (range != 0)
+		offset = offset % range;
+
+	      start = addr6part(&c->start6) + offset;
+	    }
+
+	  /* iterate until we find a free address. */
+	  addr = start;
+	  
+	  do {
+	    /* eliminate addresses in use by the server. */
+	    for (d = context; d; d = d->current)
+	      if (addr == addr6part(&d->local6))
+		break;
+	    
+	    *ans = c->start6;
+	    setaddr6part (ans, addr);
+
+	    if (!d &&
+		!lease6_find_by_addr(&c->start6, c->prefix, addr) && 
+		!config_find_by_address6(daemon->dhcp_conf, &c->start6, c->prefix, ans))
+	      return c;
+	    
+	    addr++;
+	    
+	    if (addr  == addr6part(&c->end6) + 1)
+	      addr = addr6part(&c->start6);
+	    
+	  } while (addr != start);
+	}
+	   
+  return NULL;
+}
+
+/* can dynamically allocate addr */
+struct dhcp_context *address6_available(struct dhcp_context *context, 
+					struct in6_addr *taddr,
+					struct dhcp_netid *netids,
+					int plain_range)
+{
+  u64 start, end, addr = addr6part(taddr);
+  struct dhcp_context *tmp;
+ 
+  for (tmp = context; tmp; tmp = tmp->current)
+    {
+      start = addr6part(&tmp->start6);
+      end = addr6part(&tmp->end6);
+
+      if (!(tmp->flags & (CONTEXT_STATIC | CONTEXT_RA_STATELESS)) &&
+          is_same_net6(&tmp->start6, taddr, tmp->prefix) &&
+	  is_same_net6(&tmp->end6, taddr, tmp->prefix) &&
+	  addr >= start &&
+          addr <= end &&
+          match_netid(tmp->filter, netids, plain_range))
+        return tmp;
+    }
+
+  return NULL;
+}
+
+/* address OK if configured */
+struct dhcp_context *address6_valid(struct dhcp_context *context, 
+				    struct in6_addr *taddr,
+				    struct dhcp_netid *netids,
+				    int plain_range)
+{
+  struct dhcp_context *tmp;
+ 
+  for (tmp = context; tmp; tmp = tmp->current)
+    if (is_same_net6(&tmp->start6, taddr, tmp->prefix) &&
+	match_netid(tmp->filter, netids, plain_range))
+      return tmp;
+
+  return NULL;
+}
+
+void make_duid(time_t now)
+{
+  (void)now;
+
+  if (daemon->duid_config)
+    {
+      unsigned char *p;
+      
+      daemon->duid = p = safe_malloc(daemon->duid_config_len + 6);
+      daemon->duid_len = daemon->duid_config_len + 6;
+      PUTSHORT(2, p); /* DUID_EN */
+      PUTLONG(daemon->duid_enterprise, p);
+      memcpy(p, daemon->duid_config, daemon->duid_config_len);
+    }
+  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 */
+      if (!option_bool(OPT_LEASE_RO) || daemon->lease_change_command)
+	newnow = now - 946684800;
+#endif      
+      
+      iface_enumerate(AF_LOCAL, &newnow, make_duid1);
+      
+      if(!daemon->duid)
+	die("Cannot create DHCPv6 server DUID: %s", NULL, EC_MISC);
+    }
+}
+
+static int make_duid1(int index, unsigned int type, char *mac, size_t maclen, void *parm)
+{
+  /* create DUID as specified in RFC3315. We use the MAC of the
+     first interface we find that isn't loopback or P-to-P and
+     has address-type < 256. Address types above 256 are things like 
+     tunnels which don't have usable MAC addresses. */
+  
+  unsigned char *p;
+  (void)index;
+  (void)parm;
+  time_t newnow = *((time_t *)parm);
+  
+  if (type >= 256)
+    return 1;
+
+  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;
+}
+
+struct cparam {
+  time_t now;
+  int newone, newname;
+};
+
+static int construct_worker(struct in6_addr *local, int prefix, 
+			    int scope, int if_index, int flags, 
+			    int preferred, int valid, void *vparam)
+{
+  char ifrn_name[IFNAMSIZ];
+  struct in6_addr start6, end6;
+  struct dhcp_context *template, *context;
+  struct iname *tmp;
+  
+  (void)scope;
+  (void)flags;
+  (void)valid;
+  (void)preferred;
+
+  struct cparam *param = vparam;
+
+  if (IN6_IS_ADDR_LOOPBACK(local) ||
+      IN6_IS_ADDR_LINKLOCAL(local) ||
+      IN6_IS_ADDR_MULTICAST(local))
+    return 1;
+
+  if (!(flags & IFACE_PERMANENT))
+    return 1;
+
+  if (flags & IFACE_DEPRECATED)
+    return 1;
+
+  /* Ignore interfaces where we're not doing RA/DHCP6 */
+  if (!indextoname(daemon->icmp6fd, if_index, ifrn_name) ||
+      !iface_check(AF_LOCAL, NULL, ifrn_name, NULL))
+    return 1;
+  
+  for (tmp = daemon->dhcp_except; tmp; tmp = tmp->next)
+    if (tmp->name && wildcard_match(tmp->name, ifrn_name))
+      return 1;
+
+  for (template = daemon->dhcp6; template; template = template->next)
+    if (!(template->flags & (CONTEXT_TEMPLATE | CONTEXT_CONSTRUCTED)))
+      {
+	/* non-template entries, just fill in interface and local addresses */
+	if (prefix <= template->prefix &&
+	    is_same_net6(local, &template->start6, template->prefix) &&
+	    is_same_net6(local, &template->end6, template->prefix))
+	  {
+	    /* First time found, do fast RA. */
+	    if (template->if_index == 0)
+	      {
+		ra_start_unsolicited(param->now, template);
+		param->newone = 1;
+	      }
+	    
+	    template->if_index = if_index;
+	    template->local6 = *local;
+	  }
+	
+      }
+    else if (wildcard_match(template->template_interface, ifrn_name) &&
+	     template->prefix >= prefix)
+      {
+	start6 = *local;
+	setaddr6part(&start6, addr6part(&template->start6));
+	end6 = *local;
+	setaddr6part(&end6, addr6part(&template->end6));
+	
+	for (context = daemon->dhcp6; context; context = context->next)
+	  if (!(context->flags & CONTEXT_TEMPLATE) &&
+	      IN6_ARE_ADDR_EQUAL(&start6, &context->start6) &&
+	      IN6_ARE_ADDR_EQUAL(&end6, &context->end6))
+	    {
+	      /* If there's an absolute address context covering this address
+		 then don't construct one as well. */
+	      if (!(context->flags & CONTEXT_CONSTRUCTED))
+		break;
+	      
+	      if (context->if_index == if_index)
+		{
+		  int cflags = context->flags;
+		  context->flags &= ~(CONTEXT_GC | CONTEXT_OLD);
+		  if (cflags & CONTEXT_OLD)
+		    {
+		      /* address went, now it's back, and on the same interface */
+		      log_context(AF_INET6, context); 
+		      /* fast RAs for a while */
+		      ra_start_unsolicited(param->now, context);
+		      param->newone = 1; 
+		      /* Add address to name again */
+		      if (context->flags & CONTEXT_RA_NAME)
+			param->newname = 1;
+		    
+		    }
+		  break;
+		}
+	    }
+	
+	if (!context && (context = whine_malloc(sizeof (struct dhcp_context))))
+	  {
+	    *context = *template;
+	    context->start6 = start6;
+	    context->end6 = end6;
+	    context->flags &= ~CONTEXT_TEMPLATE;
+	    context->flags |= CONTEXT_CONSTRUCTED;
+	    context->if_index = if_index;
+	    context->local6 = *local;
+	    context->saved_valid = 0;
+	    
+	    context->next = daemon->dhcp6;
+	    daemon->dhcp6 = context;
+
+	    ra_start_unsolicited(param->now, context);
+	    /* we created a new one, need to call
+	       lease_update_file to get periodic functions called */
+	    param->newone = 1; 
+
+	    /* Will need to add new putative SLAAC addresses to existing leases */
+	    if (context->flags & CONTEXT_RA_NAME)
+	      param->newname = 1;
+	    
+	    log_context(AF_INET6, context);
+	  } 
+      }
+  
+  return 1;
+}
+
+void dhcp_construct_contexts(time_t now)
+{ 
+  struct dhcp_context *context, *tmp, **up;
+  struct cparam param;
+  param.newone = 0;
+  param.newname = 0;
+  param.now = now;
+
+  for (context = daemon->dhcp6; context; context = context->next)
+    if (context->flags & CONTEXT_CONSTRUCTED)
+      context->flags |= CONTEXT_GC;
+   
+  iface_enumerate(AF_INET6, &param, construct_worker);
+
+  for (up = &daemon->dhcp6, context = daemon->dhcp6; context; context = tmp)
+    {
+      
+      tmp = context->next; 
+     
+      if (context->flags & CONTEXT_GC && !(context->flags & CONTEXT_OLD))
+	{
+	  if ((context->flags & CONTEXT_RA) || option_bool(OPT_RA))
+	    {
+	      /* previously constructed context has gone. advertise it's demise */
+	      context->flags |= CONTEXT_OLD;
+	      context->address_lost_time = now;
+	      /* Apply same ceiling of configured lease time as in radv.c */
+	      if (context->saved_valid > context->lease_time)
+		context->saved_valid = context->lease_time;
+	      /* maximum time is 2 hours, from RFC */
+	      if (context->saved_valid > 7200) /* 2 hours */
+		context->saved_valid = 7200;
+	      ra_start_unsolicited(now, context);
+	      param.newone = 1; /* include deletion */ 
+	      
+	      if (context->flags & CONTEXT_RA_NAME)
+		param.newname = 1; 
+			      
+	      log_context(AF_INET6, context);
+	      
+	      up = &context->next;
+	    }
+	  else
+	    {
+	      /* we were never doing RA for this, so free now */
+	      *up = context->next;
+	      free(context);
+	    }
+	}
+      else
+	 up = &context->next;
+    }
+  
+  if (param.newone)
+    {
+      if (daemon->dhcp || daemon->doing_dhcp6)
+	{
+	  if (param.newname)
+	    lease_update_slaac(now);
+	  lease_update_file(now);
+	}
+      else 
+	/* Not doing DHCP, so no lease system, manage alarms for ra only */
+	send_alarm(periodic_ra(now), now);
+    }
+}
+
+#endif /* HAVE_DHCP6 */