/*

 * Copyright (C) 1996-2022  Internet Software Consortium.

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM

 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL

 * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,

 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING

 * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,

 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION

 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

 *

 * SPDX-License-Identifier: ISC

 */

#include "curl_setup.h"

#ifdef HAVE_SYS_PARAM_H

#include <sys/param.h>

#endif

#ifdef HAVE_NETINET_IN_H

#include <netinet/in.h>

#endif

#ifdef HAVE_ARPA_INET_H

#include <arpa/inet.h>

#endif

#include "curlx/inet_ntop.h"

#include "curlx/snprintf.h"

#include "curlx/strcopy.h"

#define IN6ADDRSZ       16

/* #define INADDRSZ         4 */

#define INT16SZ          2

/*

 * If USE_IPV6 is disabled, we still want to parse IPv6 addresses, so make

 * sure we have _some_ value for AF_INET6 without polluting our fake value

 * everywhere.

 */

#if !defined(USE_IPV6) && !defined(AF_INET6)

#define AF_INET6 (AF_INET + 1)

#endif

/*

 * Format an IPv4 address, more or less like inet_ntop().

 *

 * Returns CURLcode.

 * Note:

 *  - uses no static variables

 *  - takes an unsigned char* not an in_addr as input

 */

static CURLcode inet_ntop4(const unsigned char *src, char *dst, size_t size)

{

  char tmp[sizeof("255.255.255.255")];

  size_t len;

  DEBUGASSERT(size >= 16);

  /* this snprintf() does not overflow the buffer. */

  SNPRINTF(tmp, sizeof(tmp), "%d.%d.%d.%d",

           ((int)((unsigned char)src[0])) & 0xff,

           ((int)((unsigned char)src[1])) & 0xff,

           ((int)((unsigned char)src[2])) & 0xff,

           ((int)((unsigned char)src[3])) & 0xff);

  len = strlen(tmp);

  if(len == 0 || len >= size)

    return CURLE_TOO_LARGE;

  curlx_strcopy(dst, size, tmp, len);

  return CURLE_OK;

}

/*

 * Convert IPv6 binary address into presentation (printable) format.

 */

static CURLcode inet_ntop6(const unsigned char *src, char *dst, size_t size)

{

  /*

   * Note that int32_t and int16_t need only be "at least" large enough

   * to contain a value of the specified size. On some systems, like

   * Crays, there is no such thing as an integer variable with 16 bits.

   * Keep this in mind if you think this function should have been coded

   * to use pointer overlays. All the world's not a VAX.

   */

  char tmp[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")];

  char *tp;

  struct {

    int base;

    int len;

  } best, cur;

  unsigned int words[IN6ADDRSZ / INT16SZ];

  int i;

  /* Preprocess:

   *  Copy the input (bytewise) array into a wordwise array.

   *  Find the longest run of 0x00's in src[] for :: shorthanding.

   */

  memset(words, '\0', sizeof(words));

  for(i = 0; i < IN6ADDRSZ; i++)

    words[i / 2] |= ((unsigned int)src[i] << ((1 - (i % 2)) << 3));

  best.base = -1;

  cur.base = -1;

  best.len = 0;

  cur.len = 0;

  for(i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {

    if(words[i] == 0) {

      if(cur.base == -1) {

        cur.base = i;

        cur.len = 1;

      }

      else

        cur.len++;

    }

    else if(cur.base != -1) {

      if(best.base == -1 || cur.len > best.len)

        best = cur;

      cur.base = -1;

    }

  }

  if((cur.base != -1) && (best.base == -1 || cur.len > best.len))

    best = cur;

  if(best.base != -1 && best.len < 2)

    best.base = -1;

  /* Format the result. */

  tp = tmp;

  for(i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {

    /* Are we inside the best run of 0x00's? */

    if(best.base != -1 && i >= best.base && i < (best.base + best.len)) {

      if(i == best.base)

        *tp++ = ':';

      continue;

    }

    /* Are we following an initial run of 0x00s or any real hex?

     */

    if(i)

      *tp++ = ':';

    /* Is this address an encapsulated IPv4?

     */

    if(i == 6 && best.base == 0 &&

       (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {

      CURLcode result = inet_ntop4(src + 12, tp, sizeof(tmp) - (tp - tmp));

      if(result)

        return result;

      tp += strlen(tp);

      break;

    }

    else {

      /* Lower-case digits. Cannot use the set from mprintf.c since this

         needs to work as a curlx function */

      static const unsigned char ldigits[] = "0123456789abcdef";

      unsigned int w = words[i];

      /* output lowercase 16-bit hex number but ignore leading zeroes */

      if(w & 0xf000)

        *tp++ = ldigits[(w & 0xf000) >> 12];

      if(w & 0xff00)

        *tp++ = ldigits[(w & 0x0f00) >> 8];

      if(w & 0xfff0)

        *tp++ = ldigits[(w & 0x00f0) >> 4];

      *tp++ = ldigits[(w & 0x000f)];

    }

  }

  /* Was it a trailing run of 0x00's?

   */

  if(best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ))

    *tp++ = ':';

  /* Check for overflow, copy, and we are done. */

  if((size_t)(tp - tmp) >= size)

    return CURLE_TOO_LARGE;

  curlx_strcopy(dst, size, tmp, tp - tmp);

  return CURLE_OK;

}

/*

 * Convert a network format address to presentation format.

 *

 * Copies result to 'buf' and returns CURLcode.

 */

CURLcode curlx_inet_ntop(int af, const void *src, char *buf, size_t size)

{

  switch(af) {

  case AF_INET:

    return inet_ntop4((const unsigned char *)src, buf, size);

  case AF_INET6:

    return inet_ntop6((const unsigned char *)src, buf, size);

  default:

    return CURLE_UNSUPPORTED_PROTOCOL;

  }

}