rt_netlink.c

大名鼎鼎的路由器源码。程序分ZEBRA、OSPFRIP等3个包。程序框架采用一个路由协议一个进程的方式

/* Looking up routing table by netlink interface. */
int
netlink_routing_table (struct sockaddr_nl *snl, struct nlmsghdr *h)
{
  int len;
  struct rtmsg *rtm;
  struct rtattr *tb [RTA_MAX + 1];
  u_char flags = 0;
  
  char anyaddr[16] = {0};

  int index;
  int table;
  void *dest;
  void *gate;

  rtm = NLMSG_DATA (h);

  if (h->nlmsg_type != RTM_NEWROUTE)
    return 0;
  if (rtm->rtm_type != RTN_UNICAST)
    return 0;

  table = rtm->rtm_table;
#if 0		/* we weed them out later in rib_weed_tables () */
  if (table != RT_TABLE_MAIN && table != rtm_table_default)
    return 0;
#endif

  len = h->nlmsg_len - NLMSG_LENGTH(sizeof (struct rtmsg));
  if (len < 0)
    return -1;

  memset (tb, 0, sizeof tb);
  netlink_parse_rtattr (tb, RTA_MAX, RTM_RTA (rtm), len);

  if (rtm->rtm_flags & RTM_F_CLONED)
    return 0;
  if (rtm->rtm_protocol == RTPROT_REDIRECT)
    return 0;
  if (rtm->rtm_protocol == RTPROT_KERNEL)
    return 0;

  if (rtm->rtm_src_len != 0)
    return 0;

  /* Route which inserted by Zebra. */
  if (rtm->rtm_protocol == RTPROT_ZEBRA)
    flags |= ZEBRA_FLAG_SELFROUTE;
  
  index = 0;
  dest = NULL;
  gate = NULL;

  if (tb[RTA_OIF])
    index = *(int *) RTA_DATA (tb[RTA_OIF]);

  if (tb[RTA_DST])
    dest = RTA_DATA (tb[RTA_DST]);
  else
    dest = anyaddr;

  /* Multipath treatment is needed. */
  if (tb[RTA_GATEWAY])
    gate = RTA_DATA (tb[RTA_GATEWAY]);

  if (rtm->rtm_family == AF_INET)
    {
      struct prefix_ipv4 p;
      p.family = AF_INET;
      memcpy (&p.prefix, dest, 4);
      p.prefixlen = rtm->rtm_dst_len;

      rib_add_ipv4 (ZEBRA_ROUTE_KERNEL, flags, &p, gate, index, table, 0, 0);
    }
#ifdef HAVE_IPV6
  if (rtm->rtm_family == AF_INET6)
    {
      struct prefix_ipv6 p;
      p.family = AF_INET6;
      memcpy (&p.prefix, dest, 16);
      p.prefixlen = rtm->rtm_dst_len;

      rib_add_ipv6 (ZEBRA_ROUTE_KERNEL, flags, &p, gate, index, table);
    }
#endif /* HAVE_IPV6 */

  return 0;
}

struct message rtproto_str [] = 
{
  {RTPROT_REDIRECT, "redirect"},
  {RTPROT_KERNEL,   "kernel"},
  {RTPROT_BOOT,     "boot"},
  {RTPROT_STATIC,   "static"},
  {RTPROT_GATED,    "GateD"},
  {RTPROT_RA,       "router advertisement"},
  {RTPROT_MRT,      "MRT"},
  {RTPROT_ZEBRA,    "Zebra"},
#ifdef RTPROT_BIRD
  {RTPROT_BIRD,     "BIRD"},
#endif /* RTPROT_BIRD */
  {0,               NULL}
};

/* Routing information change from the kernel. */
int
netlink_route_change (struct sockaddr_nl *snl, struct nlmsghdr *h)
{
  int len;
  struct rtmsg *rtm;
  struct rtattr *tb [RTA_MAX + 1];
  
  char anyaddr[16] = {0};

  int index;
  int table;
  void *dest;
  void *gate;

  rtm = NLMSG_DATA (h);

  if (! (h->nlmsg_type == RTM_NEWROUTE || h->nlmsg_type == RTM_DELROUTE))
    {
      /* If this is not route add/delete message print warning. */
      zlog_warn ("Kernel message: %d\n", h->nlmsg_type);
      return 0;
    }

  /* Connected route. */
  if (IS_ZEBRA_DEBUG_KERNEL)
    zlog_info ("%s %s %s proto %s",
	       h->nlmsg_type == RTM_NEWROUTE ? "RTM_NEWROUTE" : "RTM_DELROUTE",
	       rtm->rtm_family == AF_INET ? "ipv4" : "ipv6",
	       rtm->rtm_type == RTN_UNICAST ? "unicast" : "multicast",
	       lookup (rtproto_str, rtm->rtm_protocol));

  if (rtm->rtm_type != RTN_UNICAST)
    {
      return 0;
    }

  table = rtm->rtm_table;
  if (table != RT_TABLE_MAIN && table != rtm_table_default)
    {
      return 0;
    }

  len = h->nlmsg_len - NLMSG_LENGTH(sizeof (struct rtmsg));
  if (len < 0)
    return -1;

  memset (tb, 0, sizeof tb);
  netlink_parse_rtattr (tb, RTA_MAX, RTM_RTA (rtm), len);

  if (rtm->rtm_flags & RTM_F_CLONED)
    return 0;
  if (rtm->rtm_protocol == RTPROT_REDIRECT)
    return 0;
  if (rtm->rtm_protocol == RTPROT_KERNEL)
    return 0;

  if (rtm->rtm_protocol == RTPROT_ZEBRA && h->nlmsg_type == RTM_NEWROUTE)
    return 0;

  if (rtm->rtm_src_len != 0)
    {
      zlog_warn ("netlink_route_change(): no src len");
      return 0;
    }
  
  index = 0;
  dest = NULL;
  gate = NULL;

  if (tb[RTA_OIF])
    index = *(int *) RTA_DATA (tb[RTA_OIF]);

  if (tb[RTA_DST])
    dest = RTA_DATA (tb[RTA_DST]);
  else
    dest = anyaddr;

  if (tb[RTA_GATEWAY])
    gate = RTA_DATA (tb[RTA_GATEWAY]);

  if (rtm->rtm_family == AF_INET)
    {
      struct prefix_ipv4 p;
      p.family = AF_INET;
      memcpy (&p.prefix, dest, 4);
      p.prefixlen = rtm->rtm_dst_len;

      if (IS_ZEBRA_DEBUG_KERNEL)
	{
	  if (h->nlmsg_type == RTM_NEWROUTE)
	    zlog_info ("RTM_NEWROUTE %s/%d",
		       inet_ntoa (p.prefix), p.prefixlen);
	  else
	    zlog_info ("RTM_DELROUTE %s/%d",
		       inet_ntoa (p.prefix), p.prefixlen);
	}

      if (h->nlmsg_type == RTM_NEWROUTE)
	rib_add_ipv4 (ZEBRA_ROUTE_KERNEL, 0, &p, gate, index, table, 0, 0);
      else
	rib_delete_ipv4 (ZEBRA_ROUTE_KERNEL, 0, &p, gate, index, table);
    }

#ifdef HAVE_IPV6
  if (rtm->rtm_family == AF_INET6)
    {
      struct prefix_ipv6 p;
      char buf[BUFSIZ];

      p.family = AF_INET6;
      memcpy (&p.prefix, dest, 16);
      p.prefixlen = rtm->rtm_dst_len;

      if (IS_ZEBRA_DEBUG_KERNEL)
	{
	  if (h->nlmsg_type == RTM_NEWROUTE)
	    zlog_info ("RTM_NEWROUTE %s/%d",
		       inet_ntop (AF_INET6, &p.prefix, buf, BUFSIZ),
		       p.prefixlen);
	  else
	    zlog_info ("RTM_DELROUTE %s/%d",
		       inet_ntop (AF_INET6, &p.prefix, buf, BUFSIZ),
		       p.prefixlen);
	}

      if (h->nlmsg_type == RTM_NEWROUTE)
	rib_add_ipv6 (ZEBRA_ROUTE_KERNEL, 0, &p, gate, index, 0);
      else
	rib_delete_ipv6 (ZEBRA_ROUTE_KERNEL, 0, &p, gate, index, 0);
    }
#endif /* HAVE_IPV6 */

  return 0;
}

int
netlink_link_change (struct sockaddr_nl *snl, struct nlmsghdr *h)
{
  int len;
  struct ifinfomsg *ifi;
  struct rtattr *tb [IFLA_MAX + 1];
  struct interface *ifp;
  char *name;

  ifi = NLMSG_DATA (h);

  if (! (h->nlmsg_type == RTM_NEWLINK || h->nlmsg_type == RTM_DELLINK))
    {
      /* If this is not link add/delete message so print warning. */
      zlog_warn ("netlink_link_change: wrong kernel message %d\n",
		 h->nlmsg_type);
      return 0;
    }

  len = h->nlmsg_len - NLMSG_LENGTH (sizeof (struct ifinfomsg));
  if (len < 0)
    return -1;

  /* Looking up interface name. */
  memset (tb, 0, sizeof tb);
  netlink_parse_rtattr (tb, IFLA_MAX, IFLA_RTA (ifi), len);
  if (tb[IFLA_IFNAME] == NULL)
    return -1;
  name = (char *)RTA_DATA(tb[IFLA_IFNAME]);

  /* Add interface. */
  if (h->nlmsg_type == RTM_NEWLINK)
    {
      ifp = if_lookup_by_name (name);

      if (ifp == NULL || ! CHECK_FLAG (ifp->status, ZEBRA_INTERFACE_ACTIVE))
	{
	  if (ifp == NULL)
	    ifp = if_get_by_name (name);

	  ifp->ifindex = ifi->ifi_index;
	  ifp->flags = ifi->ifi_flags & 0x0000fffff;
	  ifp->mtu = *(int *)RTA_DATA (tb[IFLA_MTU]);
	  ifp->metric = 1;

	  /* If new link is added. */
	  if_add_update(ifp);
	}      
      else
	{
	  /* Interface status change. */
	  ifp->ifindex = ifi->ifi_index;
	  ifp->mtu = *(int *)RTA_DATA (tb[IFLA_MTU]);
	  ifp->metric = 1;

	  if (if_is_up (ifp))
	    {
	      ifp->flags = ifi->ifi_flags & 0x0000fffff;
	      if (! if_is_up (ifp))
		if_down (ifp);
	    }
	  else
	    {
	      ifp->flags = ifi->ifi_flags & 0x0000fffff;
	      if (if_is_up (ifp))
		if_up (ifp);
	    }
	}
    }
  else
    {
      /* RTM_DELLINK. */
      ifp = if_lookup_by_name (name);

      if (ifp == NULL)
	{
	  zlog (NULL, LOG_WARNING, "interface %s is deleted but can't find",
                name);
	  return 0;
	}
      
      if_delete_update (ifp);
    }

  return 0;
}

int
netlink_information_fetch (struct sockaddr_nl *snl, struct nlmsghdr *h)
{
  switch (h->nlmsg_type)
    {
    case RTM_NEWROUTE:
      return netlink_route_change (snl, h);
      break;
    case RTM_DELROUTE:
      return netlink_route_change (snl, h);
      break;
    case RTM_NEWLINK:
      return netlink_link_change (snl, h);
      break;
    case RTM_DELLINK:
      return netlink_link_change (snl, h);
      break;
    case RTM_NEWADDR:
      return netlink_interface_addr (snl, h);
      break;
    case RTM_DELADDR:
      return netlink_interface_addr (snl, h);
      break;
    default:
      zlog_warn ("Unknown netlink nlmsg_type %d\n", h->nlmsg_type);
      break;
    }
  return 0;
}

/* Interface lookup by netlink socket. */
int
interface_lookup_netlink ()
{
  int ret;

  /* Get interface information. */
  ret = netlink_request (AF_PACKET, RTM_GETLINK, &netlink_cmd);
  if (ret < 0)
    return ret;
  ret = netlink_parse_info (netlink_interface, &netlink_cmd);
  if (ret < 0)
    return ret;

  /* Get IPv4 address of the interfaces. */
  ret = netlink_request (AF_INET, RTM_GETADDR, &netlink_cmd);
  if (ret < 0)
    return ret;
  ret = netlink_parse_info (netlink_interface_addr, &netlink_cmd);
  if (ret < 0)
    return ret;

#ifdef HAVE_IPV6
  /* Get IPv6 address of the interfaces. */
  ret = netlink_request (AF_INET6, RTM_GETADDR, &netlink_cmd);
  if (ret < 0)
    return ret;
  ret = netlink_parse_info (netlink_interface_addr, &netlink_cmd);
  if (ret < 0)
    return ret;
#endif /* HAVE_IPV6 */

  return 0;
}

/* Routing table read function using netlink interface.  Only called
   bootstrap time. */
int
netlink_route_read ()
{
  int ret;

  /* Get IPv4 routing table. */
  ret = netlink_request (AF_INET, RTM_GETROUTE, &netlink_cmd);
  if (ret < 0)
    return ret;
  ret = netlink_parse_info (netlink_routing_table, &netlink_cmd);
  if (ret < 0)
    return ret;

#ifdef HAVE_IPV6
  /* Get IPv6 routing table. */
  ret = netlink_request (AF_INET6, RTM_GETROUTE, &netlink_cmd);
  if (ret < 0)
    return ret;
  ret = netlink_parse_info (netlink_routing_table, &netlink_cmd);
  if (ret < 0)
    return ret;
#endif /* HAVE_IPV6 */

  return 0;
}

/* Utility function  comes from iproute2. 
   Authors:	Alexey Kuznetsov, <[e-mail]> */
int
addattr_l (struct nlmsghdr *n, int maxlen, int type, void *data, int alen)
{
  int len;
  struct rtattr *rta;

  len = RTA_LENGTH(alen);

  if (NLMSG_ALIGN(n->nlmsg_len) + len > maxlen)
    return -1;

  rta = (struct rtattr*) (((char*)n) + NLMSG_ALIGN (n->nlmsg_len));
  rta->rta_type = type;
  rta->rta_len = len;
  memcpy (RTA_DATA(rta), data, alen);
  n->nlmsg_len = NLMSG_ALIGN (n->nlmsg_len) + len;

  return 0;
}

int
rta_addattr_l (struct rtattr *rta, int maxlen, int type, void *data, int alen)
{
  int len;
  struct rtattr *subrta;

  len = RTA_LENGTH(alen);

  if (RTA_ALIGN(rta->rta_len) + len > maxlen)
    return -1;

  subrta = (struct rtattr*) (((char*)rta) + RTA_ALIGN (rta->rta_len));
  subrta->rta_type = type;
  subrta->rta_len = len;
  memcpy (RTA_DATA(subrta), data, alen);
  rta->rta_len = NLMSG_ALIGN (rta->rta_len) + len;

  return 0;
}

/* Utility function comes from iproute2. 
   Authors:	Alexey Kuznetsov, <[e-mail]> */
int
addattr32 (struct nlmsghdr *n, int maxlen, int type, int data)
{
  int len;
  struct rtattr *rta;
  
  len = RTA_LENGTH(4);
  
  if (NLMSG_ALIGN (n->nlmsg_len) + len > maxlen)
    return -1;

  rta = (struct rtattr*) (((char*)n) + NLMSG_ALIGN (n->nlmsg_len));
  rta->rta_type = type;
  rta->rta_len = len;
  memcpy (RTA_DATA(rta), &data, 4);
  n->nlmsg_len = NLMSG_ALIGN (n->nlmsg_len) + len;

  return 0;
}

static int
netlink_talk_filter (struct sockaddr_nl *snl, struct nlmsghdr *h)
{
  zlog_warn ("netlink_talk: ignoring message type 0x%04x", h->nlmsg_type);
  return 0;
}

/* sendmsg() to netlink socket then recvmsg(). */
int
netlink_talk (struct nlmsghdr *n, struct nlsock *nl)
{
  int status;
  struct sockaddr_nl snl;