path: root/contrib/libs/c-ares/ares_gethostbyname.c

 
/* Copyright 1998, 2011, 2013 by the Massachusetts Institute of Technology. 
 * 
 * Permission to use, copy, modify, and distribute this 
 * software and its documentation for any purpose and without 
 * fee is hereby granted, provided that the above copyright 
 * notice appear in all copies and that both that copyright 
 * notice and this permission notice appear in supporting 
 * documentation, and that the name of M.I.T. not be used in 
 * advertising or publicity pertaining to distribution of the 
 * software without specific, written prior permission. 
 * M.I.T. makes no representations about the suitability of 
 * this software for any purpose.  It is provided "as is" 
 * without express or implied warranty. 
 */ 
 
#include "ares_setup.h" 
 
#ifdef HAVE_NETINET_IN_H 
#  include <netinet/in.h> 
#endif 
#ifdef HAVE_NETDB_H 
#  include <netdb.h> 
#endif 
#ifdef HAVE_ARPA_INET_H 
#  include <arpa/inet.h> 
#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 
 
#include "ares.h" 
#include "ares_inet_net_pton.h" 
#include "bitncmp.h" 
#include "ares_platform.h" 
#include "ares_nowarn.h" 
#include "ares_private.h" 
 
#ifdef WATT32 
#undef WIN32 
#endif 
 
struct host_query { 
  /* Arguments passed to ares_gethostbyname() */ 
  ares_channel channel; 
  char *name; 
  ares_host_callback callback; 
  void *arg; 
  int sent_family; /* this family is what was is being used */ 
  int want_family; /* this family is what is asked for in the API */ 
  const char *remaining_lookups; 
  int timeouts; 
}; 
 
static void next_lookup(struct host_query *hquery, int status_code); 
static void host_callback(void *arg, int status, int timeouts, 
                          unsigned char *abuf, int alen); 
static void end_hquery(struct host_query *hquery, int status, 
                       struct hostent *host); 
static int fake_hostent(const char *name, int family, 
                        ares_host_callback callback, void *arg); 
static int file_lookup(const char *name, int family, struct hostent **host); 
static void sort_addresses(struct hostent *host, 
                           const struct apattern *sortlist, int nsort); 
static void sort6_addresses(struct hostent *host, 
                            const struct apattern *sortlist, int nsort); 
static int get_address_index(const struct in_addr *addr, 
                             const struct apattern *sortlist, int nsort); 
static int get6_address_index(const struct ares_in6_addr *addr, 
                              const struct apattern *sortlist, int nsort); 
 
void ares_gethostbyname(ares_channel channel, const char *name, int family, 
                        ares_host_callback callback, void *arg) 
{ 
  struct host_query *hquery; 
 
  /* Right now we only know how to look up Internet addresses - and unspec 
     means try both basically. */ 
  switch (family) { 
  case AF_INET: 
  case AF_INET6: 
  case AF_UNSPEC: 
    break; 
  default: 
    callback(arg, ARES_ENOTIMP, 0, NULL); 
    return; 
  } 
 
  /* Per RFC 7686, reject queries for ".onion" domain names with NXDOMAIN. */
  if (ares__is_onion_domain(name))
    {
      callback(arg, ARES_ENOTFOUND, 0, NULL);
      return;
    }

  if (fake_hostent(name, family, callback, arg)) 
    return; 
 
  /* Allocate and fill in the host query structure. */ 
  hquery = ares_malloc(sizeof(struct host_query));
  if (!hquery) 
    { 
      callback(arg, ARES_ENOMEM, 0, NULL); 
      return; 
    } 
  hquery->channel = channel; 
  hquery->name = ares_strdup(name);
  hquery->want_family = family; 
  hquery->sent_family = -1; /* nothing is sent yet */ 
  if (!hquery->name) { 
    ares_free(hquery);
    callback(arg, ARES_ENOMEM, 0, NULL); 
    return; 
  } 
  hquery->callback = callback; 
  hquery->arg = arg; 
  hquery->remaining_lookups = channel->lookups; 
  hquery->timeouts = 0; 
 
  /* Start performing lookups according to channel->lookups. */ 
  next_lookup(hquery, ARES_ECONNREFUSED /* initial error code */); 
} 
 
static void next_lookup(struct host_query *hquery, int status_code) 
{ 
  const char *p; 
  struct hostent *host; 
  int status = status_code; 
 
  for (p = hquery->remaining_lookups; *p; p++) 
    { 
      switch (*p) 
        { 
        case 'b': 
          /* DNS lookup */ 
          hquery->remaining_lookups = p + 1; 
          if ((hquery->want_family == AF_INET6) || 
              (hquery->want_family == AF_UNSPEC)) { 
            /* if inet6 or unspec, start out with AAAA */ 
            hquery->sent_family = AF_INET6; 
            ares_search(hquery->channel, hquery->name, C_IN, T_AAAA, 
                        host_callback, hquery); 
          } 
          else { 
            hquery->sent_family = AF_INET; 
            ares_search(hquery->channel, hquery->name, C_IN, T_A, 
                        host_callback, hquery); 
          } 
          return; 
 
        case 'f': 
          /* Host file lookup */ 
          status = file_lookup(hquery->name, hquery->want_family, &host); 
 
          /* this status check below previously checked for !ARES_ENOTFOUND, 
             but we should not assume that this single error code is the one 
             that can occur, as that is in fact no longer the case */ 
          if (status == ARES_SUCCESS) 
            { 
              end_hquery(hquery, status, host); 
              return; 
            } 
          status = status_code;   /* Use original status code */ 
          break; 
        } 
    } 
  end_hquery(hquery, status, NULL); 
} 
 
static void host_callback(void *arg, int status, int timeouts, 
                          unsigned char *abuf, int alen) 
{ 
  struct host_query *hquery = (struct host_query *) arg; 
  ares_channel channel = hquery->channel; 
  struct hostent *host = NULL; 
 
  hquery->timeouts += timeouts; 
  if (status == ARES_SUCCESS) 
    { 
      if (hquery->sent_family == AF_INET) 
        { 
          status = ares_parse_a_reply(abuf, alen, &host, NULL, NULL); 
          if (host && channel->nsort) 
            sort_addresses(host, channel->sortlist, channel->nsort); 
        } 
      else if (hquery->sent_family == AF_INET6) 
        { 
          status = ares_parse_aaaa_reply(abuf, alen, &host, NULL, NULL); 
          if ((status == ARES_ENODATA || status == ARES_EBADRESP ||
               (status == ARES_SUCCESS && host && host->h_addr_list[0] == NULL)) &&
                hquery->want_family == AF_UNSPEC) {
            /* The query returned something but either there were no AAAA 
               records (e.g. just CNAME) or the response was malformed.  Try 
               looking up A instead. */ 
            if (host)
              ares_free_hostent(host);
            hquery->sent_family = AF_INET; 
            ares_search(hquery->channel, hquery->name, C_IN, T_A, 
                        host_callback, hquery); 
            return; 
          } 
          if (host && channel->nsort) 
            sort6_addresses(host, channel->sortlist, channel->nsort); 
        } 
      if (status == ARES_SUCCESS && host && host->h_addr_list[0] == NULL)
      {
        /* The query returned something but had no A/AAAA record
           (even after potentially retrying AAAA with A)
           so we should treat this as an error */
        status = ARES_ENODATA;
      }
      end_hquery(hquery, status, host); 
    } 
  else if ((status == ARES_ENODATA || status == ARES_EBADRESP || 
            status == ARES_ETIMEOUT) && (hquery->sent_family == AF_INET6 && 
            hquery->want_family == AF_UNSPEC)) 
    { 
      /* The AAAA query yielded no useful result.  Now look up an A instead. */ 
      hquery->sent_family = AF_INET; 
      ares_search(hquery->channel, hquery->name, C_IN, T_A, host_callback, 
                  hquery); 
    } 
  else if (status == ARES_EDESTRUCTION) 
    end_hquery(hquery, status, NULL); 
  else 
    next_lookup(hquery, status); 
} 
 
static void end_hquery(struct host_query *hquery, int status, 
                       struct hostent *host) 
{ 
  hquery->callback(hquery->arg, status, hquery->timeouts, host); 
  if (host) 
    ares_free_hostent(host); 
  ares_free(hquery->name);
  ares_free(hquery);
} 
 
/* If the name looks like an IP address, fake up a host entry, end the 
 * query immediately, and return true.  Otherwise return false. 
 */ 
static int fake_hostent(const char *name, int family, 
                        ares_host_callback callback, void *arg) 
{ 
  struct hostent hostent; 
  char *aliases[1] = { NULL }; 
  char *addrs[2]; 
  int result = 0; 
  struct in_addr in; 
  struct ares_in6_addr in6; 
 
  if (family == AF_INET || family == AF_INET6) 
    { 
      /* It only looks like an IP address if it's all numbers and dots. */ 
      int numdots = 0, valid = 1; 
      const char *p; 
      for (p = name; *p; p++) 
        { 
          if (!ISDIGIT(*p) && *p != '.') { 
            valid = 0; 
            break; 
          } else if (*p == '.') { 
            numdots++; 
          } 
        } 
 
      /* if we don't have 3 dots, it is illegal 
       * (although inet_pton doesn't think so).
       */ 
      if (numdots != 3 || !valid) 
        result = 0; 
      else 
        result = (ares_inet_pton(AF_INET, name, &in) < 1 ? 0 : 1);
 
      if (result) 
        family = AF_INET; 
    } 
  if (family == AF_INET6) 
    result = (ares_inet_pton(AF_INET6, name, &in6) < 1 ? 0 : 1); 
 
  if (!result) 
    return 0; 
 
  if (family == AF_INET) 
    { 
      hostent.h_length = (int)sizeof(struct in_addr); 
      addrs[0] = (char *)&in; 
    } 
  else if (family == AF_INET6) 
    { 
      hostent.h_length = (int)sizeof(struct ares_in6_addr); 
      addrs[0] = (char *)&in6; 
    } 
  /* Duplicate the name, to avoid a constness violation. */ 
  hostent.h_name = ares_strdup(name);
  if (!hostent.h_name) 
    { 
      callback(arg, ARES_ENOMEM, 0, NULL); 
      return 1; 
    } 
 
  /* Fill in the rest of the host structure and terminate the query. */ 
  addrs[1] = NULL; 
  hostent.h_aliases = aliases; 
  hostent.h_addrtype = aresx_sitoss(family); 
  hostent.h_addr_list = addrs; 
  callback(arg, ARES_SUCCESS, 0, &hostent); 
 
  ares_free((char *)(hostent.h_name));
  return 1; 
} 
 
/* This is an API method */ 
int ares_gethostbyname_file(ares_channel channel, const char *name, 
                            int family, struct hostent **host) 
{ 
  int result; 
 
  /* We only take the channel to ensure that ares_init() been called. */ 
  if(channel == NULL) 
    { 
      /* Anything will do, really.  This seems fine, and is consistent with 
         other error cases. */ 
      *host = NULL; 
      return ARES_ENOTFOUND; 
    } 
 
  /* Just chain to the internal implementation we use here; it's exactly 
   * what we want. 
   */ 
  result = file_lookup(name, family, host); 
  if(result != ARES_SUCCESS) 
    { 
      /* We guarantee a NULL hostent on failure. */ 
      *host = NULL; 
    } 
  return result; 
} 
 
static int file_lookup(const char *name, int family, struct hostent **host) 
{ 
  FILE *fp; 
  char **alias; 
  int status; 
  int error; 
 
#ifdef WIN32 
  char PATH_HOSTS[MAX_PATH]; 
  win_platform platform; 
 
  PATH_HOSTS[0] = '\0'; 
 
  platform = ares__getplatform(); 
 
  if (platform == WIN_NT) { 
    char tmp[MAX_PATH]; 
    HKEY hkeyHosts; 
 
    if (RegOpenKeyExA(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0, KEY_READ,
                     &hkeyHosts) == ERROR_SUCCESS) 
    { 
      DWORD dwLength = MAX_PATH; 
      RegQueryValueExA(hkeyHosts, DATABASEPATH, NULL, NULL, (LPBYTE)tmp,
                      &dwLength); 
      ExpandEnvironmentStringsA(tmp, PATH_HOSTS, MAX_PATH);
      RegCloseKey(hkeyHosts); 
    } 
  } 
  else if (platform == WIN_9X) 
    GetWindowsDirectoryA(PATH_HOSTS, MAX_PATH);
  else 
    return ARES_ENOTFOUND; 
 
  strcat(PATH_HOSTS, WIN_PATH_HOSTS); 
 
#elif defined(WATT32) 
  extern const char *_w32_GetHostsFile (void); 
  const char *PATH_HOSTS = _w32_GetHostsFile(); 
 
  if (!PATH_HOSTS) 
    return ARES_ENOTFOUND; 
#endif 
 
  /* Per RFC 7686, reject queries for ".onion" domain names with NXDOMAIN. */
  if (ares__is_onion_domain(name))
    return ARES_ENOTFOUND;


  fp = fopen(PATH_HOSTS, "r"); 
  if (!fp) 
    { 
      error = ERRNO; 
      switch(error) 
        { 
        case ENOENT: 
        case ESRCH: 
          return ARES_ENOTFOUND; 
        default: 
          DEBUGF(fprintf(stderr, "fopen() failed with error: %d %s\n", 
                         error, strerror(error))); 
          DEBUGF(fprintf(stderr, "Error opening file: %s\n", 
                         PATH_HOSTS)); 
          *host = NULL; 
          return ARES_EFILE; 
        } 
    } 
  while ((status = ares__get_hostent(fp, family, host)) == ARES_SUCCESS) 
    { 
      if (strcasecmp((*host)->h_name, name) == 0) 
        break; 
      for (alias = (*host)->h_aliases; *alias; alias++) 
        { 
          if (strcasecmp(*alias, name) == 0) 
            break; 
        } 
      if (*alias) 
        break; 
      ares_free_hostent(*host); 
    } 
  fclose(fp); 
  if (status == ARES_EOF) 
    status = ARES_ENOTFOUND; 
  if (status != ARES_SUCCESS) 
    *host = NULL; 
  return status; 
} 
 
static void sort_addresses(struct hostent *host, 
                           const struct apattern *sortlist, int nsort) 
{ 
  struct in_addr a1, a2; 
  int i1, i2, ind1, ind2; 
 
  /* This is a simple insertion sort, not optimized at all.  i1 walks 
   * through the address list, with the loop invariant that everything 
   * to the left of i1 is sorted.  In the loop body, the value at i1 is moved 
   * back through the list (via i2) until it is in sorted order. 
   */ 
  for (i1 = 0; host->h_addr_list[i1]; i1++) 
    { 
      memcpy(&a1, host->h_addr_list[i1], sizeof(struct in_addr)); 
      ind1 = get_address_index(&a1, sortlist, nsort); 
      for (i2 = i1 - 1; i2 >= 0; i2--) 
        { 
          memcpy(&a2, host->h_addr_list[i2], sizeof(struct in_addr)); 
          ind2 = get_address_index(&a2, sortlist, nsort); 
          if (ind2 <= ind1) 
            break; 
          memcpy(host->h_addr_list[i2 + 1], &a2, sizeof(struct in_addr)); 
        } 
      memcpy(host->h_addr_list[i2 + 1], &a1, sizeof(struct in_addr)); 
    } 
} 
 
/* Find the first entry in sortlist which matches addr.  Return nsort 
 * if none of them match. 
 */ 
static int get_address_index(const struct in_addr *addr, 
                             const struct apattern *sortlist, 
                             int nsort) 
{ 
  int i; 
 
  for (i = 0; i < nsort; i++) 
    { 
      if (sortlist[i].family != AF_INET) 
        continue; 
      if (sortlist[i].type == PATTERN_MASK) 
        { 
          if ((addr->s_addr & sortlist[i].mask.addr4.s_addr) 
              == sortlist[i].addrV4.s_addr) 
            break; 
        } 
      else 
        { 
          if (!ares__bitncmp(&addr->s_addr, &sortlist[i].addrV4.s_addr, 
                             sortlist[i].mask.bits)) 
            break; 
        } 
    } 
  return i; 
} 
 
static void sort6_addresses(struct hostent *host, 
                            const struct apattern *sortlist, int nsort) 
{ 
  struct ares_in6_addr a1, a2; 
  int i1, i2, ind1, ind2; 
 
  /* This is a simple insertion sort, not optimized at all.  i1 walks 
   * through the address list, with the loop invariant that everything 
   * to the left of i1 is sorted.  In the loop body, the value at i1 is moved 
   * back through the list (via i2) until it is in sorted order. 
   */ 
  for (i1 = 0; host->h_addr_list[i1]; i1++) 
    { 
      memcpy(&a1, host->h_addr_list[i1], sizeof(struct ares_in6_addr)); 
      ind1 = get6_address_index(&a1, sortlist, nsort); 
      for (i2 = i1 - 1; i2 >= 0; i2--) 
        { 
          memcpy(&a2, host->h_addr_list[i2], sizeof(struct ares_in6_addr)); 
          ind2 = get6_address_index(&a2, sortlist, nsort); 
          if (ind2 <= ind1) 
            break; 
          memcpy(host->h_addr_list[i2 + 1], &a2, sizeof(struct ares_in6_addr)); 
        } 
      memcpy(host->h_addr_list[i2 + 1], &a1, sizeof(struct ares_in6_addr)); 
    } 
} 
 
/* Find the first entry in sortlist which matches addr.  Return nsort 
 * if none of them match. 
 */ 
static int get6_address_index(const struct ares_in6_addr *addr, 
                              const struct apattern *sortlist, 
                              int nsort) 
{ 
  int i; 
 
  for (i = 0; i < nsort; i++) 
    { 
      if (sortlist[i].family != AF_INET6) 
        continue; 
      if (!ares__bitncmp(addr, &sortlist[i].addrV6, sortlist[i].mask.bits)) 
        break; 
    } 
  return i; 
}