chrony/nameserv.c

/*
  chronyd/chronyc - Programs for keeping computer clocks accurate.

 **********************************************************************
 * Copyright (C) Richard P. Curnow  1997-2003
 * Copyright (C) Miroslav Lichvar  2009-2011
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 * 
 * This program 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
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 * 
 **********************************************************************

  =======================================================================

  Functions to do name to IP address conversion

  */

#include "config.h"

#include "sysincl.h"

#include <netdb.h>
#include <resolv.h>

#include "nameserv.h"
#include "socket.h"
#include "util.h"

/* ================================================== */

static int address_family = IPADDR_UNSPEC;

void
DNS_SetAddressFamily(int family)
{
  address_family = family;
}

DNS_Status 
DNS_Name2IPAddress(const char *name, IPAddr *ip_addrs, int max_addrs)
{
  struct addrinfo hints, *res, *ai;
  int i, result;
  IPAddr ip;

  max_addrs = MIN(max_addrs, DNS_MAX_ADDRESSES);

  for (i = 0; i < max_addrs; i++)
    ip_addrs[i].family = IPADDR_UNSPEC;

  /* Avoid calling getaddrinfo() if the name is an IP address */
  if (UTI_StringToIP(name, &ip)) {
    if (address_family != IPADDR_UNSPEC && ip.family != address_family)
      return DNS_Failure;
    if (max_addrs >= 1)
      ip_addrs[0] = ip;
    return DNS_Success;
  }

  memset(&hints, 0, sizeof (hints));

  switch (address_family) {
    case IPADDR_INET4:
      hints.ai_family = AF_INET;
      break;
#ifdef FEAT_IPV6
    case IPADDR_INET6:
      hints.ai_family = AF_INET6;
      break;
#endif
    default:
      hints.ai_family = AF_UNSPEC;
  }
  hints.ai_socktype = SOCK_DGRAM;

  result = getaddrinfo(name, NULL, &hints, &res);

  if (result) {
#ifdef FORCE_DNSRETRY
    return DNS_TryAgain;
#else
    return result == EAI_AGAIN ? DNS_TryAgain : DNS_Failure;
#endif
  }

  for (ai = res, i = 0; i < max_addrs && ai != NULL; ai = ai->ai_next) {
    switch (ai->ai_family) {
      case AF_INET:
        if (address_family != IPADDR_UNSPEC && address_family != IPADDR_INET4)
          continue;
        ip_addrs[i].family = IPADDR_INET4;
        ip_addrs[i].addr.in4 = ntohl(((struct sockaddr_in *)ai->ai_addr)->sin_addr.s_addr);
        i++;
        break;
#ifdef FEAT_IPV6
      case AF_INET6:
        if (address_family != IPADDR_UNSPEC && address_family != IPADDR_INET6)
          continue;
        /* Don't return an address that would lose a scope ID */
        if (((struct sockaddr_in6 *)ai->ai_addr)->sin6_scope_id != 0)
          continue;
        ip_addrs[i].family = IPADDR_INET6;
        memcpy(&ip_addrs[i].addr.in6, &((struct sockaddr_in6 *)ai->ai_addr)->sin6_addr.s6_addr,
               sizeof (ip_addrs->addr.in6));
        i++;
        break;
#endif
    }
  }

  freeaddrinfo(res);

  return !max_addrs || ip_addrs[0].family != IPADDR_UNSPEC ? DNS_Success : DNS_Failure;
}

/* ================================================== */

int
DNS_IPAddress2Name(IPAddr *ip_addr, char *name, int len)
{
  char *result = NULL;
#ifdef FEAT_IPV6
  struct sockaddr_in6 saddr;
#else
  struct sockaddr_in saddr;
#endif
  IPSockAddr ip_saddr;
  socklen_t slen;
  char hbuf[NI_MAXHOST];

  ip_saddr.ip_addr = *ip_addr;
  ip_saddr.port = 0;

  slen = SCK_IPSockAddrToSockaddr(&ip_saddr, (struct sockaddr *)&saddr, sizeof (saddr));
  if (!getnameinfo((struct sockaddr *)&saddr, slen, hbuf, sizeof (hbuf), NULL, 0, 0))
    result = hbuf;

  if (result == NULL)
    result = UTI_IPToString(ip_addr);
  if (snprintf(name, len, "%s", result) >= len)
    return 0;

  return 1;
}

/* ================================================== */

void
DNS_Reload(void)
{
  res_init();
}

/* ================================================== */