curl/lib/if2ip.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2022, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * SPDX-License-Identifier: curl
 *
 ***************************************************************************/

#include "curl_setup.h"

#ifdef HAVE_NETINET_IN_H
#  include <netinet/in.h>
#endif
#ifdef HAVE_ARPA_INET_H
#  include <arpa/inet.h>
#endif
#ifdef HAVE_NET_IF_H
#  include <net/if.h>
#endif
#ifdef HAVE_SYS_IOCTL_H
#  include <sys/ioctl.h>
#endif
#ifdef HAVE_NETDB_H
#  include <netdb.h>
#endif
#ifdef HAVE_SYS_SOCKIO_H
#  include <sys/sockio.h>
#endif
#ifdef HAVE_IFADDRS_H
#  include <ifaddrs.h>
#endif
#ifdef HAVE_STROPTS_H
#  include <stropts.h>
#endif
#ifdef __VMS
#  include <inet.h>
#endif

#include "inet_ntop.h"
#include "strcase.h"
#include "if2ip.h"
/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h"
#include "memdebug.h"

/* ------------------------------------------------------------------ */

#ifdef ENABLE_IPV6
/* Return the scope of the given address. */
unsigned int Curl_ipv6_scope(const struct sockaddr *sa)
{
  if(sa->sa_family == AF_INET6) {
    const struct sockaddr_in6 * sa6 = (const struct sockaddr_in6 *)(void *) sa;
    const unsigned char *b = sa6->sin6_addr.s6_addr;
    unsigned short w = (unsigned short) ((b[0] << 8) | b[1]);

    if((b[0] & 0xFE) == 0xFC) /* Handle ULAs */
      return IPV6_SCOPE_UNIQUELOCAL;
    switch(w & 0xFFC0) {
    case 0xFE80:
      return IPV6_SCOPE_LINKLOCAL;
    case 0xFEC0:
      return IPV6_SCOPE_SITELOCAL;
    case 0x0000:
      w = b[1] | b[2] | b[3] | b[4] | b[5] | b[6] | b[7] | b[8] | b[9] |
          b[10] | b[11] | b[12] | b[13] | b[14];
      if(w || b[15] != 0x01)
        break;
      return IPV6_SCOPE_NODELOCAL;
    default:
      break;
    }
  }
  return IPV6_SCOPE_GLOBAL;
}
#endif

#if defined(HAVE_GETIFADDRS)

if2ip_result_t Curl_if2ip(int af,
#ifdef ENABLE_IPV6
                          unsigned int remote_scope,
                          unsigned int local_scope_id,
#endif
                          const char *interf,
                          char *buf, int buf_size)
{
  struct ifaddrs *iface, *head;
  if2ip_result_t res = IF2IP_NOT_FOUND;

#if defined(ENABLE_IPV6) && \
    !defined(HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID)
  (void) local_scope_id;
#endif

  if(getifaddrs(&head) >= 0) {
    for(iface = head; iface != NULL; iface = iface->ifa_next) {
      if(iface->ifa_addr) {
        if(iface->ifa_addr->sa_family == af) {
          if(strcasecompare(iface->ifa_name, interf)) {
            void *addr;
            const char *ip;
            char scope[12] = "";
            char ipstr[64];
#ifdef ENABLE_IPV6
            if(af == AF_INET6) {
#ifdef HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID
              unsigned int scopeid = 0;
#endif
              unsigned int ifscope = Curl_ipv6_scope(iface->ifa_addr);

              if(ifscope != remote_scope) {
                /* We are interested only in interface addresses whose scope
                   matches the remote address we want to connect to: global
                   for global, link-local for link-local, etc... */
                if(res == IF2IP_NOT_FOUND)
                  res = IF2IP_AF_NOT_SUPPORTED;
                continue;
              }

              addr =
                &((struct sockaddr_in6 *)(void *)iface->ifa_addr)->sin6_addr;
#ifdef HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID
              /* Include the scope of this interface as part of the address */
              scopeid = ((struct sockaddr_in6 *)(void *)iface->ifa_addr)
                            ->sin6_scope_id;

              /* If given, scope id should match. */
              if(local_scope_id && scopeid != local_scope_id) {
                if(res == IF2IP_NOT_FOUND)
                  res = IF2IP_AF_NOT_SUPPORTED;

                continue;
              }

              if(scopeid)
                msnprintf(scope, sizeof(scope), "%%%u", scopeid);
#endif
            }
            else
#endif
              addr =
                &((struct sockaddr_in *)(void *)iface->ifa_addr)->sin_addr;
            res = IF2IP_FOUND;
            ip = Curl_inet_ntop(af, addr, ipstr, sizeof(ipstr));
            msnprintf(buf, buf_size, "%s%s", ip, scope);
            break;
          }
        }
        else if((res == IF2IP_NOT_FOUND) &&
                strcasecompare(iface->ifa_name, interf)) {
          res = IF2IP_AF_NOT_SUPPORTED;
        }
      }
    }

    freeifaddrs(head);
  }

  return res;
}

#elif defined(HAVE_IOCTL_SIOCGIFADDR)

if2ip_result_t Curl_if2ip(int af,
#ifdef ENABLE_IPV6
                          unsigned int remote_scope,
                          unsigned int local_scope_id,
#endif
                          const char *interf,
                          char *buf, int buf_size)
{
  struct ifreq req;
  struct in_addr in;
  struct sockaddr_in *s;
  curl_socket_t dummy;
  size_t len;
  const char *r;

#ifdef ENABLE_IPV6
  (void)remote_scope;
  (void)local_scope_id;
#endif

  if(!interf || (af != AF_INET))
    return IF2IP_NOT_FOUND;

  len = strlen(interf);
  if(len >= sizeof(req.ifr_name))
    return IF2IP_NOT_FOUND;

  dummy = socket(AF_INET, SOCK_STREAM, 0);
  if(CURL_SOCKET_BAD == dummy)
    return IF2IP_NOT_FOUND;

  memset(&req, 0, sizeof(req));
  memcpy(req.ifr_name, interf, len + 1);
  req.ifr_addr.sa_family = AF_INET;

  if(ioctl(dummy, SIOCGIFADDR, &req) < 0) {
    sclose(dummy);
    /* With SIOCGIFADDR, we cannot tell the difference between an interface
       that does not exist and an interface that has no address of the
       correct family. Assume the interface does not exist */
    return IF2IP_NOT_FOUND;
  }

  s = (struct sockaddr_in *)(void *)&req.ifr_addr;
  memcpy(&in, &s->sin_addr, sizeof(in));
  r = Curl_inet_ntop(s->sin_family, &in, buf, buf_size);

  sclose(dummy);
  if(!r)
    return IF2IP_NOT_FOUND;
  return IF2IP_FOUND;
}

#else

if2ip_result_t Curl_if2ip(int af,
#ifdef ENABLE_IPV6
                          unsigned int remote_scope,
                          unsigned int local_scope_id,
#endif
                          const char *interf,
                          char *buf, int buf_size)
{
    (void) af;
#ifdef ENABLE_IPV6
    (void) remote_scope;
    (void) local_scope_id;
#endif
    (void) interf;
    (void) buf;
    (void) buf_size;
    return IF2IP_NOT_FOUND;
}

#endif