text: /***************************************************************************
   *                                  _   _ ____  _
   *  Project                     ___| | | |  _ \| |
   *                             / __| | | | |_) | |
   *                            | (__| |_| |  _ <| |___
   *                             \___|\___/|_| \_\_____|
   *
   * Copyright (C) 1998 - 2020, 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.haxx.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.
   *
   ***************************************************************************/
  
  #include "curl_setup.h"
  
  /***********************************************************************
   * Only for IPv6-enabled builds
   **********************************************************************/
  #ifdef CURLRES_IPV6
  
  #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 __VMS
  #include <in.h>
  #include <inet.h>
  #endif
  
  #ifdef HAVE_PROCESS_H
  #include <process.h>
  #endif
  
  #include <fcntl.h>
  #include "urldata.h"
  #include "sendf.h"
  #include "hostip.h"
  #include "hash.h"
  #include "share.h"
  #include "strerror.h"
  #include "url.h"
  #include "inet_pton.h"
  #include "connect.h"
  /* The last 3 #include files should be in this order */
  #include "curl_printf.h"
  #include "curl_memory.h"
  #include "memdebug.h"
  
  /*
   * Curl_ipv6works() returns TRUE if IPv6 seems to work.
   */
  bool Curl_ipv6works(struct connectdata *conn)
  {
    if(conn) {
      /* the nature of most system is that IPv6 status doesn't come and go
         during a program's lifetime so we only probe the first time and then we
         have the info kept for fast re-use */
      DEBUGASSERT(conn);
      DEBUGASSERT(conn->data);
      DEBUGASSERT(conn->data->multi);
      return conn->data->multi->ipv6_works;
    }
    else {
      int ipv6_works = -1;
      /* probe to see if we have a working IPv6 stack */
      curl_socket_t s = socket(PF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, 0);
      if(s == CURL_SOCKET_BAD)
        /* an IPv6 address was requested but we can't get/use one */
        ipv6_works = 0;
      else {
        ipv6_works = 1;
        Curl_closesocket(NULL, s);
      }
      return (ipv6_works>0)?TRUE:FALSE;
    }
  }
  
  /*
   * Curl_ipvalid() checks what CURL_IPRESOLVE_* requirements that might've
   * been set and returns TRUE if they are OK.
   */
  bool Curl_ipvalid(struct connectdata *conn)
  {
    if(conn->ip_version == CURL_IPRESOLVE_V6)
      return Curl_ipv6works(conn);
  
    return TRUE;
  }
  
  #if defined(CURLRES_SYNCH)
  
  #ifdef DEBUG_ADDRINFO
  static void dump_addrinfo(struct connectdata *conn,
                            const struct Curl_addrinfo *ai)
  {
    printf("dump_addrinfo:\n");
    for(; ai; ai = ai->ai_next) {
      char buf[INET6_ADDRSTRLEN];
      printf("    fam %2d, CNAME %s, ",
             ai->ai_family, ai->ai_canonname ? ai->ai_canonname : "<none>");
      Curl_printable_address(ai, buf, sizeof(buf));
      printf("%s\n", buf);
    }
  }
  #else
  #define dump_addrinfo(x,y) Curl_nop_stmt
  #endif
  
  /*
   * Curl_getaddrinfo() when built IPv6-enabled (non-threading and
   * non-ares version).
   *
   * Returns name information about the given hostname and port number. If
   * successful, the 'addrinfo' is returned and the forth argument will point to
   * memory we need to free after use. That memory *MUST* be freed with
   * Curl_freeaddrinfo(), nothing else.
   */
  struct Curl_addrinfo *Curl_getaddrinfo(struct connectdata *conn,
                                         const char *hostname,
                                         int port,
                                         int *waitp)
  {
    struct addrinfo hints;
    struct Curl_addrinfo *res;
    int error;
    char sbuf[12];
    char *sbufptr = NULL;
  #ifndef USE_RESOLVE_ON_IPS
    char addrbuf[128];
  #endif
    int pf;
  #if !defined(CURL_DISABLE_VERBOSE_STRINGS)
    struct Curl_easy *data = conn->data;
  #endif
  
    *waitp = 0; /* synchronous response only */
  
    /* Check if a limited name resolve has been requested */
    switch(conn->ip_version) {
    case CURL_IPRESOLVE_V4:
      pf = PF_INET;
      break;
    case CURL_IPRESOLVE_V6:
      pf = PF_INET6;
      break;
    default:
      pf = PF_UNSPEC;
      break;
    }
  
    if((pf != PF_INET) && !Curl_ipv6works(conn))
      /* The stack seems to be a non-IPv6 one */
      pf = PF_INET;
  
    memset(&hints, 0, sizeof(hints));
    hints.ai_family = pf;
    hints.ai_socktype = (conn->transport == TRNSPRT_TCP) ?
      SOCK_STREAM : SOCK_DGRAM;
  
  #ifndef USE_RESOLVE_ON_IPS
    /*
     * The AI_NUMERICHOST must not be set to get synthesized IPv6 address from
     * an IPv4 address on iOS and Mac OS X.
     */
    if((1 == Curl_inet_pton(AF_INET, hostname, addrbuf)) ||
       (1 == Curl_inet_pton(AF_INET6, hostname, addrbuf))) {
      /* the given address is numerical only, prevent a reverse lookup */
      hints.ai_flags = AI_NUMERICHOST;
    }
  #endif
  
    if(port) {
      msnprintf(sbuf, sizeof(sbuf), "%d", port);
      sbufptr = sbuf;
    }
  
    error = Curl_getaddrinfo_ex(hostname, sbufptr, &hints, &res);
    if(error) {
      infof(data, "getaddrinfo(3) failed for %s:%d\n", hostname, port);
      return NULL;
    }
  
    if(port) {
      Curl_addrinfo_set_port(res, port);
    }
  
    dump_addrinfo(conn, res);
  
    return res;
  }
  #endif /* CURLRES_SYNCH */
  
  #endif /* CURLRES_IPV6 */
  