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libcares/ares_parse_aaaa_reply.c  view on Meta::CPAN

#endif
#ifdef HAVE_ARPA_NAMESER_H
#  include <arpa/nameser.h>
#else
#  include "nameser.h"
#endif
#ifdef HAVE_ARPA_NAMESER_COMPAT_H
#  include <arpa/nameser_compat.h>
#endif

#ifdef HAVE_STRINGS_H
#  include <strings.h>
#endif

#ifdef HAVE_LIMITS_H
#  include <limits.h>
#endif

#include "ares.h"
#include "ares_dns.h"
#include "ares_inet_net_pton.h"
#include "ares_private.h"

int ares__parse_aaaa_reply(const unsigned char *abuf, int alen,
                           struct hostent **host, struct ares_addrinfo **ai,
                           unsigned short port, char **cname,
                           struct ares_addr6ttl *addrttls, int *naddrttls)
{
  unsigned int qdcount, ancount;
  int status, i, rr_type, rr_class, rr_len, rr_ttl, naddrs;
  int cname_ttl = INT_MAX;  /* the TTL imposed by the CNAME chain */
  int naliases;
  long len;
  const unsigned char *aptr;
  char *hostname, *rr_name, *rr_data, **aliases;
  struct ares_in6_addr *addrs;
  struct hostent *hostent;
  struct ares_addrinfo *nested_ai, *head_ai = NULL;
  struct sockaddr_in6 *sin;
  const int max_addr_ttls = (addrttls && naddrttls) ? *naddrttls : 0;

  /* Set *host to NULL for all failure cases. */
  if (host)
    *host = NULL;
  /* Same with *naddrttls. */
  if (naddrttls)
    *naddrttls = 0;

  /* Give up if abuf doesn't have room for a header. */
  if (alen < HFIXEDSZ)
    return ARES_EBADRESP;

  /* Fetch the question and answer count from the header. */
  qdcount = DNS_HEADER_QDCOUNT(abuf);
  ancount = DNS_HEADER_ANCOUNT(abuf);
  if (qdcount != 1)
    return ARES_EBADRESP;

  /* Expand the name from the question, and skip past the question. */
  aptr = abuf + HFIXEDSZ;
  status = ares__expand_name_for_response(aptr, abuf, alen, &hostname, &len);
  if (status != ARES_SUCCESS)
    return status;
  if (aptr + len + QFIXEDSZ > abuf + alen)
    {
      ares_free(hostname);
      return ARES_EBADRESP;
    }
  aptr += len + QFIXEDSZ;

  /* Allocate addresses and aliases; ancount gives an upper bound for both. */
  if (host)
    {
      addrs = ares_malloc(ancount * sizeof(struct ares_in6_addr));
      if (!addrs)
        {
          ares_free(hostname);
          return ARES_ENOMEM;
        }
      aliases = ares_malloc((ancount + 1) * sizeof(char *));
      if (!aliases)
        {
          ares_free(hostname);
          ares_free(addrs);
          return ARES_ENOMEM;
        }
    }
  /* Allocate addresses; ancount gives an upper bound. */
  else if (ai)
    {
      addrs = ares_malloc(ancount * sizeof(struct ares_in6_addr));
      if (!addrs)
        {
          ares_free(hostname);
          return ARES_ENOMEM;
        }
      aliases = NULL;
    }
  else
    {
      addrs = NULL;
      aliases = NULL;
    }
  naddrs = 0;
  naliases = 0;

  /* Examine each answer resource record (RR) in turn. */
  for (i = 0; i < (int)ancount; i++)
    {
      /* Decode the RR up to the data field. */
      status = ares__expand_name_for_response(aptr, abuf, alen, &rr_name, &len);
      if (status != ARES_SUCCESS)
        break;
      aptr += len;
      if (aptr + RRFIXEDSZ > abuf + alen)
        {
          ares_free(rr_name);
          status = ARES_EBADRESP;
          break;
        }
      rr_type = DNS_RR_TYPE(aptr);
      rr_class = DNS_RR_CLASS(aptr);
      rr_len = DNS_RR_LEN(aptr);
      rr_ttl = DNS_RR_TTL(aptr);
      aptr += RRFIXEDSZ;
      if (aptr + rr_len > abuf + alen)
        {
          ares_free(rr_name);
          status = ARES_EBADRESP;
          break;
        }

      if (rr_class == C_IN && rr_type == T_AAAA
          && rr_len == sizeof(struct ares_in6_addr)
          && strcasecmp(rr_name, hostname) == 0)
        {
          if (addrs)
            {
              if (aptr + sizeof(struct ares_in6_addr) > abuf + alen)
              {  /* LCOV_EXCL_START: already checked above */
                ares_free(rr_name);
                status = ARES_EBADRESP;
                break;
              }  /* LCOV_EXCL_STOP */
              memcpy(&addrs[naddrs], aptr, sizeof(struct ares_in6_addr));
            }
          if (naddrs < max_addr_ttls)
            {
              struct ares_addr6ttl * const at = &addrttls[naddrs];
              if (aptr + sizeof(struct ares_in6_addr) > abuf + alen)
              {  /* LCOV_EXCL_START: already checked above */
                ares_free(rr_name);
                status = ARES_EBADRESP;
                break;
              }  /* LCOV_EXCL_STOP */
              memcpy(&at->ip6addr, aptr,  sizeof(struct ares_in6_addr));
              at->ttl = rr_ttl;
            }
          naddrs++;
          status = ARES_SUCCESS;
        }

      if (rr_class == C_IN && rr_type == T_CNAME)
        {
          /* Record the RR name as an alias. */
          if (aliases)
            aliases[naliases] = rr_name;
          else
            ares_free(rr_name);
          naliases++;

          /* Decode the RR data and replace the hostname with it. */
          status = ares__expand_name_for_response(aptr, abuf, alen, &rr_data,
                                                  &len);
          if (status != ARES_SUCCESS)
            break;
          ares_free(hostname);
          hostname = rr_data;

          /* Take the min of the TTLs we see in the CNAME chain. */
          if (cname_ttl > rr_ttl)
            cname_ttl = rr_ttl;
        }
      else
        ares_free(rr_name);

      aptr += rr_len;
      if (aptr > abuf + alen)
        {  /* LCOV_EXCL_START: already checked above */
          status = ARES_EBADRESP;
          break;
        }  /* LCOV_EXCL_STOP */
    }

  /* the check for naliases to be zero is to make sure CNAME responses
     don't get caught here */
  if (status == ARES_SUCCESS && naddrs == 0 && naliases == 0)
    status = ARES_ENODATA;
  if (status == ARES_SUCCESS)
    {
      /* We got our answer. */
      if (naddrttls)
        {
          const int n = naddrs < max_addr_ttls ? naddrs : max_addr_ttls;
          for (i = 0; i < n; i++)
            {
              /* Ensure that each A TTL is no larger than the CNAME TTL. */
              if (addrttls[i].ttl > cname_ttl)
                addrttls[i].ttl = cname_ttl;
            }
          *naddrttls = n;
        }
      if (aliases)
        aliases[naliases] = NULL;
      if (host)
        {
          /* Allocate memory to build the host entry. */
          hostent = ares_malloc(sizeof(struct hostent));
          if (hostent)
            {
              hostent->h_addr_list = ares_malloc((naddrs + 1) * sizeof(char *));
              if (hostent->h_addr_list)
                {
                  /* Fill in the hostent and return successfully. */
                  hostent->h_name = hostname;
                  hostent->h_aliases = aliases;
                  hostent->h_addrtype = AF_INET6;
                  hostent->h_length = sizeof(struct ares_in6_addr);
                  for (i = 0; i < naddrs; i++)
                    hostent->h_addr_list[i] = (char *) &addrs[i];
                  hostent->h_addr_list[naddrs] = NULL;
                  if (!naddrs && addrs)
                    ares_free(addrs);