ifaddrs.c

glibc 2.9,最新版的C语言库函数

	}
    }

  /* Return if no interface is up.  */
  if ((newlink + newaddr) == 0)
    goto exit_free;

  /* 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)
    {
      result = -1;
      goto exit_free;
    }

  /* Table for mapping kernel index to entry in our list.  */
  map_newlink_data = alloca (newlink * sizeof (int));
  memset (map_newlink_data, '\xff', newlink * sizeof (int));

  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 */

	  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, ifas,
				       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:
		      if (rta_payload <= sizeof (ifas[ifa_index].addr))
			{
			  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:
		      if (rta_payload <= sizeof (ifas[ifa_index].broadaddr))
			{
			  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;
			  *(char *) __mempcpy (ifas[ifa_index].name, rta_data,
					       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 the interfaces. Theoretically 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, ifas,
				    map_newlink_data, newlink)].ifa.ifa_flags;
	      if (ifa_index > 0)
		ifas[ifa_index - 1].ifa.ifa_next = &ifas[ifa_index].ifa;
	      ++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:
			    /* Size must match that of an address for IPv4.  */
			    if (rta_payload == 4)
			      memcpy (&((struct sockaddr_in *) sa)->sin_addr,
				      rta_data, rta_payload);
			    break;

			  case AF_INET6:
			    /* Size must match that of an address for IPv6.  */
			    if (rta_payload == 16)
			      {
				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_index;
			      }
			    break;

			  default:
			    if (rta_payload <= sizeof (ifas[ifa_index].addr))
			      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:
			  /* Size must match that of an address for IPv4.  */
			  if (rta_payload == 4)
			    memcpy (&ifas[ifa_index].addr.s4.sin_addr,
				  rta_data, rta_payload);
			  break;

			case AF_INET6:
			  /* Size must match that of an address for IPv6.  */
			  if (rta_payload == 16)
			    {
			      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_index;
			    }
			  break;

			default:
			  if (rta_payload <= sizeof (ifas[ifa_index].addr))
			    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:
			  /* Size must match that of an address for IPv4.  */
			  if (rta_payload == 4)
			    memcpy (&ifas[ifa_index].broadaddr.s4.sin_addr,
				    rta_data, rta_payload);
			  break;

			case AF_INET6:
			  /* Size must match that of an address for IPv6.  */
			  if (rta_payload == 16)
			    {
			      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_index;
			    }
			  break;

			default:
			  if (rta_payload <= sizeof (ifas[ifa_index].addr))
			    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;
			  *(char *) __mempcpy (ifas[ifa_index].name, rta_data,
					       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, ifas,
				      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;
		    }
		}
	    }
	}
    }

  assert (ifa_data_ptr <= (char *) &ifas[newlink + newaddr] + ifa_data_size);

  if (newaddr_idx > 0)
    {
      for (i = 0; i < newlink; ++i)
	if (map_newlink_data[i] == -1)
	  {
	    /* We have fewer links then we anticipated.  Adjust the
	       forward pointer to the first address entry.  */
	    ifas[i - 1].ifa.ifa_next = &ifas[newlink].ifa;
	  }

      if (i == 0 && newlink > 0)
	/* No valid link, but we allocated memory.  We have to
	   populate the first entry.  */
	memmove (ifas, &ifas[newlink], sizeof (struct ifaddrs_storage));
    }

  *ifap = &ifas[0].ifa;

 exit_free:
  __netlink_free_handle (&nh);
  __netlink_close (&nh);

  return result;
}
libc_hidden_def (getifaddrs)


#if __ASSUME_NETLINK_SUPPORT != 0
void
freeifaddrs (struct ifaddrs *ifa)
{
  free (ifa);
}
libc_hidden_def (freeifaddrs)
#endif