Update.

2003-03-28  Thorsten Kukuk  <kukuk@suse.de>

	* sysdeps/unix/sysv/linux/ifaddrs.c: New file.
	* inet/test-ifaddrs.c: Allow AF_PACKET.
	* sysdeps/unix/sysv/linux/kernel-features.h: Add
	__ASSUME_NETLINK_SUPPORT.

2 files changed, 776 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/ifaddrs.c b/sysdeps/unix/sysv/linux/ifaddrs.c
new file mode 100644
index 0000000000..3921c40dc7
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/ifaddrs.c
@@ -0,0 +1,770 @@
+/* getifaddrs -- get names and addresses of all network interfaces
+   Copyright (C) 2003 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <assert.h>
+#include <errno.h>
+#include <ifaddrs.h>
+#include <net/if.h>
+#include <netinet/in.h>
+#include <netpacket/packet.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sysdep.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <asm/types.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+
+#include "kernel-features.h"
+
+/* We don't know if we have NETLINK support compiled in in our
+   Kernel, so include the old implementation as fallback.  */
+#if __ASSUME_NETLINK_SUPPORT == 0
+static int no_netlink_support;
+
+#define getifaddrs fallback_getifaddrs
+#include "sysdeps/gnu/ifaddrs.c"
+#undef getifaddrs
+
+#endif
+
+
+struct netlink_res
+{
+  struct netlink_res *next;
+  struct nlmsghdr *nlh;
+  size_t size;			/* Size of response.  */
+  uint32_t seq;			/* sequential number we used.  */
+};
+
+
+struct netlink_handle
+{
+  int fd;			/* Netlink file descriptor.  */
+  pid_t pid;			/* Process ID.  */
+  uint32_t seq;			/* The sequence number we use currently.  */
+  struct netlink_res *nlm_list;	/* Pointer to list of responses.  */
+  struct netlink_res *end_ptr;	/* For faster append of new entries.  */
+};
+
+
+/* struct to hold the data for one ifaddrs entry, so we can allocate
+   everything at once.  */
+struct ifaddrs_storage
+{
+  struct ifaddrs ifa;
+  union
+  {
+    /* Save space for the biggest of the four used sockaddr types and
+       avoid a lot of casts.  */
+    struct sockaddr sa;
+    struct sockaddr_ll sl;
+    struct sockaddr_in s4;
+    struct sockaddr_in6 s6;
+  } addr, netmask, broadaddr;
+  char name[IF_NAMESIZE + 1];
+};
+
+
+static void
+free_netlink_handle (struct netlink_handle *h)
+{
+  struct netlink_res *ptr;
+  int saved_errno = errno;
+
+  ptr = h->nlm_list;
+  while (ptr != NULL)
+    {
+      struct netlink_res *tmpptr;
+
+      free (ptr->nlh);
+      tmpptr = ptr->next;
+      free (ptr);
+      ptr = tmpptr;
+    }
+
+  errno = saved_errno;
+}
+
+
+static int
+netlink_sendreq (struct netlink_handle *h, int type)
+{
+  struct
+  {
+    struct nlmsghdr nlh;
+    struct rtgenmsg g;
+  } req;
+  struct sockaddr_nl nladdr;
+
+  if (h->seq == 0)
+    h->seq = time (NULL);
+
+  req.nlh.nlmsg_len = sizeof (req);
+  req.nlh.nlmsg_type = type;
+  req.nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST;
+  req.nlh.nlmsg_pid = 0;
+  req.nlh.nlmsg_seq = h->seq;
+  req.g.rtgen_family = AF_UNSPEC;
+
+  memset (&nladdr, '\0', sizeof (nladdr));
+  nladdr.nl_family = AF_NETLINK;
+
+  return TEMP_FAILURE_RETRY (sendto (h->fd, (void *) &req, sizeof (req), 0,
+				     (struct sockaddr *) &nladdr,
+				     sizeof (nladdr)));
+}
+
+
+static int
+netlink_receive (struct netlink_handle *h)
+{
+  struct netlink_res *nlm_next;
+  char buf[4096];
+  struct iovec iov = { buf, sizeof (buf) };
+  struct sockaddr_nl nladdr;
+  struct nlmsghdr *nlmh;
+  int read_len;
+  bool done = false;
+
+  while (! done)
+    {
+      struct msghdr msg =
+	{
+	  (void *) &nladdr, sizeof (nladdr),
+	  &iov, 1,
+	  NULL, 0,
+	  0
+	};
+
+      read_len = TEMP_FAILURE_RETRY (recvmsg (h->fd, &msg, 0));
+      if (read_len < 0)
+	return -1;
+
+      if (msg.msg_flags & MSG_TRUNC)
+	return -1;
+
+      nlm_next = (struct netlink_res *) malloc (sizeof (struct netlink_res));
+      if (nlm_next == NULL)
+	return -1;
+      nlm_next->next = NULL;
+      nlm_next->nlh = (struct nlmsghdr *) malloc (read_len);
+      if (nlm_next->nlh == NULL)
+	{
+	  free (nlm_next);
+	  return -1;
+	}
+      memcpy (nlm_next->nlh, buf, read_len);
+      nlm_next->size = read_len;
+      nlm_next->seq = h->seq;
+      if (h->nlm_list == NULL)
+	{
+	  h->nlm_list = nlm_next;
+	  h->end_ptr = nlm_next;
+	}
+      else
+	{
+	  h->end_ptr->next = nlm_next;
+	  h->end_ptr = nlm_next;
+	}
+
+      for (nlmh = (struct nlmsghdr *) buf;
+	   NLMSG_OK (nlmh, (size_t) read_len);
+	   nlmh = (struct nlmsghdr *) NLMSG_NEXT (nlmh, read_len))
+	{
+	  if ((pid_t) nlmh->nlmsg_pid != h->pid || nlmh->nlmsg_seq != h->seq)
+	    continue;
+
+	  if (nlmh->nlmsg_type == NLMSG_DONE)
+	    {
+	      /* we found the end, leave the loop.  */
+	      done = true;
+	      break;
+	    }
+	  if (nlmh->nlmsg_type == NLMSG_ERROR)
+	    {
+	      struct nlmsgerr *nlerr = (struct nlmsgerr *) NLMSG_DATA (nlmh);
+	      if (nlmh->nlmsg_len < NLMSG_LENGTH (sizeof (struct nlmsgerr)))
+		errno = EIO;
+	      else
+		errno = -nlerr->error;
+	      return -1;
+	    }
+	}
+    }
+  return 0;
+}
+
+
+static void
+netlink_close (struct netlink_handle *h)
+{
+  /* Don't modify errno.  */
+  INTERNAL_SYSCALL_DECL (err);
+  (void) INTERNAL_SYSCALL (close, err, 1, h->fd);
+}
+
+
+/* Open a NETLINK socket.  */
+static int
+netlink_open (struct netlink_handle *h)
+{
+  struct sockaddr_nl nladdr;
+
+  h->fd = socket (PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+  if (h->fd < 0)
+    return -1;
+
+  memset (&nladdr, '\0', sizeof (nladdr));
+  nladdr.nl_family = AF_NETLINK;
+  if (bind (h->fd, (struct sockaddr *) &nladdr, sizeof (nladdr)) < 0)
+    {
+      netlink_close (h);
+      return -1;
+    }
+  return 0;
+}
+
+
+/* We know the number of RTM_NEWLINK entries, so we reserve the first
+   # of entries for this type. All RTM_NEWADDR entries have an index
+   pointer to the RTM_NEWLINK entry.  To find the entry, create
+   a table to map kernel index entries to our index numbers.
+   Since we get at first all RTM_NEWLINK entries, it can never happen
+   that a RTM_NEWADDR index is not known to this map.  */
+static int
+map_newlink (int index, int *map, int max)
+{
+  int i;
+
+  for (i = 0; i < max; i++)
+    {
+      if (map[i] == -1)
+	{
+	  map[i] = index;
+	  return i;
+	}
+      else if (map[i] == index)
+	return i;
+    }
+  /* This should never be reached. If this will be reached, we have
+     very big problem.  */
+  abort ();
+}
+
+
+/* Create a linked list of `struct ifaddrs' structures, one for each
+   network interface on the host machine.  If successful, store the
+   list in *IFAP and return 0.  On errors, return -1 and set `errno'.  */
+int
+getifaddrs (struct ifaddrs **ifap)
+{
+  struct netlink_handle nh = { 0, 0, 0, NULL, NULL };
+  struct netlink_res *nlp;
+  struct ifaddrs_storage *ifas;
+  unsigned int i, newlink, newaddr, newaddr_idx;
+  int *map_newlink_data;
+  size_t ifa_data_size = 0;  /* Size to allocate for all ifa_data.  */
+  char *ifa_data_ptr;        /* Pointer to the unused part of memory for
+				ifa_data.  */
+
+  if (ifap)
+    *ifap = NULL;
+
+  if (netlink_open (&nh) < 0)
+    {
+#if __ASSUME_NETLINK_SUPPORT == 0
+       no_netlink_support = 1;
+#else
+       return -1;
+#endif
+    }
+
+#if __ASSUME_NETLINK_SUPPORT == 0
+  if (no_netlink_support)
+    return fallback_getifaddrs (ifap);
+#endif
+
+  nh.pid = getpid ();
+
+  /* Tell the kernel that we wish to get a list of all
+     active interfaces.  */
+  if (netlink_sendreq (&nh, RTM_GETLINK) < 0)
+    {
+      netlink_close (&nh);
+      return -1;
+    }
+  /* Collect all data for every interface.  */
+  if (netlink_receive (&nh) < 0)
+    {
+      free_netlink_handle (&nh);
+      netlink_close (&nh);
+      return -1;
+    }
+
+
+  /* Now ask the kernel for all addresses which are assigned
+     to an interface.  Since we store the addresses after the
+     interfaces in the list, we will later always find the
+     interface before the corresponding addresses.  */
+  ++nh.seq;
+  if (netlink_sendreq (&nh, RTM_GETADDR) < 0)
+    {
+      free_netlink_handle (&nh);
+      netlink_close (&nh);
+      return -1;
+    }
+  /* Collect all data for every inerface.  */
+  if (netlink_receive (&nh) < 0)
+    {
+      free_netlink_handle (&nh);
+      netlink_close (&nh);
+      return -1;
+    }
+
+  /* Count all RTM_NEWLINK and RTM_NEWADDR entries to allocate
+     enough memory.  */
+  newlink = newaddr = 0;
+  for (nlp = nh.nlm_list; nlp; nlp = nlp->next)
+    {
+      struct nlmsghdr *nlh;
+      size_t size = nlp->size;
+
+      if (nlp->nlh == NULL)
+	continue;
+
+      /* Walk through all entries we got from the kernel and look, which
+         message type they contain.  */
+      for (nlh = nlp->nlh; NLMSG_OK (nlh, size); nlh = NLMSG_NEXT (nlh, size))
+	{
+	  /* check if the message is what we want */
+	  if ((pid_t) nlh->nlmsg_pid != nh.pid || nlh->nlmsg_seq != nlp->seq)
+	    continue;
+
+	  if (nlh->nlmsg_type == NLMSG_DONE)
+	    break;		/* ok */
+
+	  if (nlh->nlmsg_type == RTM_NEWLINK)
+	    {
+	      /* A RTM_NEWLINK message can have IFLA_STATS data. We need to
+		 know the size before creating the list to allocate enough
+		 memory.  */
+	      struct ifinfomsg *ifim = (struct ifinfomsg *) NLMSG_DATA (nlh);
+	      struct rtattr *rta = IFLA_RTA (ifim);
+	      size_t rtasize = IFLA_PAYLOAD (nlh);
+
+	      while (RTA_OK (rta, rtasize))
+		{
+		  size_t rta_payload = RTA_PAYLOAD (rta);
+
+		  if (rta->rta_type == IFLA_STATS)
+		    {
+		      ifa_data_size += rta_payload;
+		      break;
+		    }
+		  else
+		    rta = RTA_NEXT (rta, rtasize);
+		}
+	      ++newlink;
+	    }
+	  else if (nlh->nlmsg_type == RTM_NEWADDR)
+	    ++newaddr;
+	}
+    }
+
+  /* Return if no interface is up.  */
+  if ((newlink + newaddr) == 0)
+    {
+      free_netlink_handle (&nh);
+      netlink_close (&nh);
+      return 0;
+    }
+
+  /* Table for mapping kernel index to entry in our list.  */
+  map_newlink_data = alloca (newlink * sizeof (int));
+
+  /* Allocate memory for all entries we have and initialize next
+     pointer.  */
+  ifas = (struct ifaddrs_storage *) calloc (1,
+					    (newlink + newaddr)
+					    * sizeof (struct ifaddrs_storage)
+					    + ifa_data_size);
+  if (ifas == NULL)
+    {
+      free_netlink_handle (&nh);
+      netlink_close (&nh);
+      return -1;
+    }
+
+  for (i = 0; i < newlink + newaddr - 1; i++)
+    {
+      ifas[i].ifa.ifa_next = &ifas[i + 1].ifa;
+      map_newlink_data[i] = -1;
+    }
+  ifa_data_ptr = (char *)&ifas[newlink + newaddr];
+  newaddr_idx = 0;		/* Counter for newaddr index.  */
+
+  /* Walk through the list of data we got from the kernel.  */
+  for (nlp = nh.nlm_list; nlp; nlp = nlp->next)
+    {
+      struct nlmsghdr *nlh;
+      size_t size = nlp->size;
+
+      if (nlp->nlh == NULL)
+	continue;
+
+      /* Walk through one message and look at the type: If it is our
+	 message, we need RTM_NEWLINK/RTM_NEWADDR and stop if we reach
+	 the end or we find the end marker (in this case we ignore the
+	 following data.  */
+      for (nlh = nlp->nlh; NLMSG_OK (nlh, size); nlh = NLMSG_NEXT (nlh, size))
+	{
+	  int ifa_index = 0;
+
+	  /* check if the message is the one we want */
+	  if ((pid_t) nlh->nlmsg_pid != nh.pid || nlh->nlmsg_seq != nlp->seq)
+	    continue;
+
+	  if (nlh->nlmsg_type == NLMSG_DONE)
+	    break;		/* ok */
+	  else if (nlh->nlmsg_type == RTM_NEWLINK)
+	    {
+	      /* We found a new interface. Now extract everything from the
+		 interface data we got and need.  */
+	      struct ifinfomsg *ifim = (struct ifinfomsg *) NLMSG_DATA (nlh);
+	      struct rtattr *rta = IFLA_RTA (ifim);
+	      size_t rtasize = IFLA_PAYLOAD (nlh);
+
+	      /* interfaces are stored in the first "newlink" entries
+		 of our list, starting in the order as we got from the
+		 kernel.  */
+              ifa_index = map_newlink (ifim->ifi_index - 1,
+				       map_newlink_data, newlink);
+	      ifas[ifa_index].ifa.ifa_flags = ifim->ifi_flags;
+
+	      while (RTA_OK (rta, rtasize))
+		{
+		  char *rta_data = RTA_DATA (rta);
+		  size_t rta_payload = RTA_PAYLOAD (rta);
+
+		  switch (rta->rta_type)
+		    {
+		    case IFLA_ADDRESS:
+		      ifas[ifa_index].addr.sl.sll_family = AF_PACKET;
+		      memcpy (ifas[ifa_index].addr.sl.sll_addr,
+			      (char *) rta_data, rta_payload);
+		      ifas[ifa_index].addr.sl.sll_halen = rta_payload;
+		      ifas[ifa_index].addr.sl.sll_ifindex = ifim->ifi_index;
+		      ifas[ifa_index].addr.sl.sll_hatype = ifim->ifi_type;
+
+		      ifas[ifa_index].ifa.ifa_addr = &ifas[ifa_index].addr.sa;
+		      break;
+
+		    case IFLA_BROADCAST:
+		      ifas[ifa_index].broadaddr.sl.sll_family = AF_PACKET;
+		      memcpy (ifas[ifa_index].broadaddr.sl.sll_addr,
+			      (char *) rta_data, rta_payload);
+		      ifas[ifa_index].broadaddr.sl.sll_halen = rta_payload;
+		      ifas[ifa_index].broadaddr.sl.sll_ifindex
+			= ifim->ifi_index;
+		      ifas[ifa_index].broadaddr.sl.sll_hatype = ifim->ifi_type;
+
+		      ifas[ifa_index].ifa.ifa_broadaddr
+			= &ifas[ifa_index].broadaddr.sa;
+		      break;
+
+		    case IFLA_IFNAME:	/* Name of Interface */
+		      if ((rta_payload + 1) <= sizeof (ifas[ifa_index].name))
+			{
+			  ifas[ifa_index].ifa.ifa_name = ifas[ifa_index].name;
+			  strncpy (ifas[ifa_index].name, rta_data,
+				   rta_payload);
+			  ifas[ifa_index].name[rta_payload] = '\0';
+			}
+		      break;
+
+		    case IFLA_STATS:	/* Statistics of Interface */
+		      ifas[ifa_index].ifa.ifa_data = ifa_data_ptr;
+		      ifa_data_ptr += rta_payload;
+		      memcpy (ifas[ifa_index].ifa.ifa_data, rta_data,
+			      rta_payload);
+		      break;
+
+		    case IFLA_UNSPEC:
+		      break;
+		    case IFLA_MTU:
+		      break;
+		    case IFLA_LINK:
+		      break;
+		    case IFLA_QDISC:
+		      break;
+		    default:
+		      break;
+		    }
+
+		  rta = RTA_NEXT (rta, rtasize);
+		}
+	    }
+	  else if (nlh->nlmsg_type == RTM_NEWADDR)
+	    {
+	      struct ifaddrmsg *ifam = (struct ifaddrmsg *) NLMSG_DATA (nlh);
+	      struct rtattr *rta = IFA_RTA (ifam);
+	      size_t rtasize = IFA_PAYLOAD (nlh);
+
+	      /* New Addresses are stored in the order we got them from
+		 the kernel after interfaces. Theoretical it is possible
+		 that we have holes in the interface part of the list,
+		 but we always have already the interface for this address.  */
+	      ifa_index = newlink + newaddr_idx;
+	      ifas[ifa_index].ifa.ifa_flags
+		= ifas[map_newlink (ifam->ifa_index - 1,
+				    map_newlink_data, newlink)].ifa.ifa_flags;
+	      ++newaddr_idx;
+
+	      while (RTA_OK (rta, rtasize))
+		{
+		  char *rta_data = RTA_DATA (rta);
+		  size_t rta_payload = RTA_PAYLOAD (rta);
+
+		  switch (rta->rta_type)
+		    {
+		    case IFA_ADDRESS:
+		      {
+			struct sockaddr *sa;
+
+			if (ifas[ifa_index].ifa.ifa_addr != NULL)
+			  {
+			    /* In a point-to-poing network IFA_ADDRESS
+			       contains the destination address, local
+			       address is supplied in IFA_LOCAL attribute.
+			       destination address and broadcast address
+			       are stored in an union, so it doesn't matter
+			       which name we use.  */
+			    ifas[ifa_index].ifa.ifa_broadaddr
+			      = &ifas[ifa_index].broadaddr.sa;
+			    sa = &ifas[ifa_index].broadaddr.sa;
+			  }
+			else
+			  {
+			    ifas[ifa_index].ifa.ifa_addr
+			      = &ifas[ifa_index].addr.sa;
+			    sa = &ifas[ifa_index].addr.sa;
+			  }
+
+			sa->sa_family = ifam->ifa_family;
+
+			switch (ifam->ifa_family)
+			  {
+			  case AF_INET:
+			    memcpy (&((struct sockaddr_in *) sa)->sin_addr,
+				    rta_data, rta_payload);
+			    break;
+
+			  case AF_INET6:
+			    memcpy (&((struct sockaddr_in6 *) sa)->sin6_addr,
+				    rta_data, rta_payload);
+			    if (IN6_IS_ADDR_LINKLOCAL (rta_data) ||
+				IN6_IS_ADDR_MC_LINKLOCAL (rta_data))
+			      ((struct sockaddr_in6 *) sa)->sin6_scope_id =
+				ifam->ifa_scope;
+			    break;
+
+			  default:
+			    memcpy (sa->sa_data, rta_data, rta_payload);
+			    break;
+			  }
+		      }
+		      break;
+
+		    case IFA_LOCAL:
+		      if (ifas[ifa_index].ifa.ifa_addr != NULL)
+			{
+			  /* If ifa_addr is set and we get IFA_LOCAL,
+			     assume we have a point-to-point network.
+			     Move address to correct field.  */
+			  ifas[ifa_index].broadaddr = ifas[ifa_index].addr;
+			  ifas[ifa_index].ifa.ifa_broadaddr
+			    = &ifas[ifa_index].broadaddr.sa;
+			  memset (&ifas[ifa_index].addr, '\0',
+				  sizeof (ifas[ifa_index].addr));
+			}
+
+		      ifas[ifa_index].ifa.ifa_addr = &ifas[ifa_index].addr.sa;
+		      ifas[ifa_index].ifa.ifa_addr->sa_family
+			= ifam->ifa_family;
+
+		      switch (ifam->ifa_family)
+			{
+			case AF_INET:
+			  memcpy (&ifas[ifa_index].addr.s4.sin_addr,
+				  rta_data, rta_payload);
+			  break;
+
+			case AF_INET6:
+			  memcpy (&ifas[ifa_index].addr.s6.sin6_addr,
+				  rta_data, rta_payload);
+			  if (IN6_IS_ADDR_LINKLOCAL (rta_data) ||
+			      IN6_IS_ADDR_MC_LINKLOCAL (rta_data))
+			    ifas[ifa_index].addr.s6.sin6_scope_id =
+			      ifam->ifa_scope;
+			  break;
+
+			default:
+			  memcpy (ifas[ifa_index].addr.sa.sa_data,
+				  rta_data, rta_payload);
+			  break;
+			}
+		      break;
+
+		    case IFA_BROADCAST:
+		      /* We get IFA_BROADCAST, so IFA_LOCAL was too much.  */
+		      if (ifas[ifa_index].ifa.ifa_broadaddr != NULL)
+			memset (&ifas[ifa_index].broadaddr, '\0',
+				sizeof (ifas[ifa_index].broadaddr));
+
+		      ifas[ifa_index].ifa.ifa_broadaddr
+			= &ifas[ifa_index].broadaddr.sa;
+		      ifas[ifa_index].ifa.ifa_broadaddr->sa_family
+			= ifam->ifa_family;
+
+		      switch (ifam->ifa_family)
+			{
+			case AF_INET:
+			  memcpy (&ifas[ifa_index].broadaddr.s4.sin_addr,
+				  rta_data, rta_payload);
+			  break;
+
+			case AF_INET6:
+			  memcpy (&ifas[ifa_index].broadaddr.s6.sin6_addr,
+				  rta_data, rta_payload);
+			  if (IN6_IS_ADDR_LINKLOCAL (rta_data) ||
+			      IN6_IS_ADDR_MC_LINKLOCAL (rta_data))
+			    ifas[ifa_index].broadaddr.s6.sin6_scope_id =
+			      ifam->ifa_scope;
+			  break;
+
+			default:
+			  memcpy (&ifas[ifa_index].broadaddr.sa.sa_data,
+				  rta_data, rta_payload);
+			  break;
+			}
+		      break;
+
+		    case IFA_LABEL:
+		      if (rta_payload + 1 <= sizeof (ifas[ifa_index].name))
+			{
+			  ifas[ifa_index].ifa.ifa_name = ifas[ifa_index].name;
+			  strncpy (ifas[ifa_index].name, rta_data,
+				   rta_payload);
+			  ifas[ifa_index].name[rta_payload] = '\0';
+			}
+		      else
+			abort ();
+		      break;
+
+		    case IFA_UNSPEC:
+		      break;
+		    case IFA_CACHEINFO:
+		      break;
+		    default:
+		      break;
+		    }
+
+		  rta = RTA_NEXT (rta, rtasize);
+		}
+
+	      /* If we didn't get the interface name with the
+		 address, use the name from the interface entry.  */
+	      if (ifas[ifa_index].ifa.ifa_name == NULL)
+		ifas[ifa_index].ifa.ifa_name
+		  = ifas[map_newlink (ifam->ifa_index - 1,
+				      map_newlink_data, newlink)].ifa.ifa_name;
+
+	      /* Calculate the netmask.  */
+	      if (ifas[ifa_index].ifa.ifa_addr
+		  && ifas[ifa_index].ifa.ifa_addr->sa_family != AF_UNSPEC
+		  && ifas[ifa_index].ifa.ifa_addr->sa_family != AF_PACKET)
+		{
+		  uint32_t max_prefixlen = 0;
+		  char *cp = NULL;
+
+		  ifas[ifa_index].ifa.ifa_netmask
+		    = &ifas[ifa_index].netmask.sa;
+
+		  switch (ifas[ifa_index].ifa.ifa_addr->sa_family)
+		    {
+		    case AF_INET:
+		      cp = (char *) &ifas[ifa_index].netmask.s4.sin_addr;
+		      max_prefixlen = 32;
+		      break;
+
+		    case AF_INET6:
+		      cp = (char *) &ifas[ifa_index].netmask.s6.sin6_addr;
+		      max_prefixlen = 128;
+		      break;
+		    }
+
+		  ifas[ifa_index].ifa.ifa_netmask->sa_family
+		    = ifas[ifa_index].ifa.ifa_addr->sa_family;
+
+		  if (cp != NULL)
+		    {
+		      char c;
+		      unsigned int preflen;
+
+		      if ((max_prefixlen > 0) &&
+			  (ifam->ifa_prefixlen > max_prefixlen))
+			preflen = max_prefixlen;
+		      else
+			preflen = ifam->ifa_prefixlen;
+
+		      for (i = 0; i < (preflen / 8); i++)
+			*cp++ = 0xff;
+		      c = 0xff;
+		      c <<= (8 - (preflen % 8));
+		      *cp = c;
+		    }
+		}
+	    }
+	}
+    }
+
+  free_netlink_handle (&nh);
+
+  netlink_close (&nh);
+
+  if (ifap != NULL)
+    *ifap = &ifas[0].ifa;
+
+  return 0;
+}
+
+
+#if __ASSUME_NETLINK_SUPPORT != 0
+void
+freeifaddrs (struct ifaddrs *ifa)
+{
+  free (ifa);
+}
+#endif
diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h
index 9909b75393..b016b6c077 100644
--- a/sysdeps/unix/sysv/linux/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/kernel-features.h
@@ -279,3 +279,9 @@
     && (defined __ia64__ || defined __s390__ || defined __powerpc__)
 # define __ASSUME_CLONE_THREAD_FLAGS	1
 #endif
+
+/* With kernel 2.4.17 we always have netlink support.  */
+#if __LINUX_KERNEL_VERSION >= (132096+17)
+# define __ASSUME_NETLINK_SUPPORT	1
+#endif
+