/*

 * Copyright (c) 2012-2015 Tim Ruehsen

 * Copyright (c) 2015-2024 Free Software Foundation, Inc.

 *

 * This file is part of libwget.

 *

 * Libwget is free software: you can redistribute it and/or modify

 * it under the terms of the GNU Lesser General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * Libwget 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 Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with libwget.  If not, see <https://www.gnu.org/licenses/>.

 *

 *

 * a collection of charset encoding routines

 *

 * Changelog

 * 02.10.2013  Tim Ruehsen  created

 *

 */

#include <config.h>

#include <string.h>

#include <errno.h>

#ifdef HAVE_ICONV

# include <iconv.h>

#endif

#include <langinfo.h>

#if defined HAVE_IDN2_H && defined WITH_LIBIDN2

# include <idn2.h>

#elif defined HAVE_IDNA_H && defined WITH_LIBIDN

# include <idna.h>

# ifdef _WIN32

#   include <idn-free.h>

# endif

#elif defined HAVE_IDN_IDNA_H && defined WITH_LIBIDN

// OpenSolaris uses the idn subdir

# include <idn/idna.h>

#endif

#include <wget.h>

#include "private.h"

const char *wget_local_charset_encoding(void)

{

  const char *encoding = nl_langinfo(CODESET);

  if (encoding && *encoding)

    return wget_strdup(encoding);

  return wget_strdup("ASCII");

}

// void *wget_memiconv(const void *src, size_t length, const char *src_encoding, const char *dst_encoding)

int wget_memiconv(const char *src_encoding, const void *src, size_t srclen, const char *dst_encoding, char **out, size_t *outlen)

{

  if (!src)

    return WGET_E_INVALID;

#ifdef HAVE_ICONV

  if (!src_encoding)

    src_encoding = "iso-8859-1"; // default character-set for most browsers

  if (!dst_encoding)

    dst_encoding = "iso-8859-1"; // default character-set for most browsers

  if (wget_strcasecmp_ascii(src_encoding, dst_encoding)) {

    int ret = WGET_E_UNKNOWN;

    iconv_t cd = iconv_open(dst_encoding, src_encoding);

    if (cd != (iconv_t)-1) {

      char *tmp = (char *) src; // iconv won't change where src points to, but changes tmp itself

      size_t tmp_len = srclen;

      size_t dst_len = tmp_len * 6, dst_len_tmp = dst_len;

      char *dst = wget_malloc(dst_len + 1), *dst_tmp = dst;

      if (!dst) {

        iconv_close(cd);

        return WGET_E_MEMORY;

      }

      errno = 0;

      if (iconv(cd, (ICONV_CONST char **)&tmp, &tmp_len, &dst_tmp, &dst_len_tmp) == 0

        && iconv(cd, NULL, NULL, &dst_tmp, &dst_len_tmp) == 0)

      {

        debug_printf("transcoded %zu bytes from '%s' to '%s'\n", srclen, src_encoding, dst_encoding);

        if (out) {

          // here we reduce the allocated memory size, if it fails we use the original memory chunk

          tmp = wget_realloc(dst, dst_len - dst_len_tmp + 1);

          if (!tmp)

            tmp = dst;

          tmp[dst_len - dst_len_tmp] = 0;

          *out = tmp;

        } else

          xfree(dst);

        if (outlen)

          *outlen = dst_len - dst_len_tmp;

        ret = WGET_E_SUCCESS;

      } else {

        // erno == 0 means some codepoints were encoded non-reversible, treat as error

        error_printf(_("Failed to transcode '%s' string into '%s' (%d)\n"), src_encoding, dst_encoding, errno);

        xfree(dst);

        if (out)

          *out = NULL;

        if (outlen)

          *outlen = 0;

      }

      iconv_close(cd);

    } else

      error_printf(_("Failed to prepare transcoding '%s' into '%s' (%d)\n"), src_encoding, dst_encoding, errno);

    return ret;

  }

#endif

  if (out)

    *out = wget_strmemdup(src, srclen);

  if (outlen)

    *outlen = srclen;

  return WGET_E_SUCCESS;

}

// src must be a ASCII compatible C string

char *wget_striconv(const char *src, const char *src_encoding, const char *dst_encoding)

{

  if (!src)

    return NULL;

  char *dst;

  if (wget_memiconv(src_encoding, src, strlen(src), dst_encoding, &dst, NULL))

    return NULL;

  return dst;

}

bool wget_str_needs_encoding(const char *s)

{

  if (!s)

    return false;

  while (*s && (*s & ~0x7f) == 0) s++;

  return *s != 0;

}

bool wget_str_is_valid_utf8(const char *utf8)

{

  const unsigned char *s = (const unsigned char *) utf8;

  if (!s)

    return 0;

  while (*s) {

    if ((*s & 0x80) == 0) /* 0xxxxxxx ASCII char */

      s++;

    else if ((*s & 0xE0) == 0xC0) /* 110xxxxx 10xxxxxx */ {

      if ((s[1] & 0xC0) != 0x80)

        return 0;

      s += 2;

    } else if ((*s & 0xF0) == 0xE0) /* 1110xxxx 10xxxxxx 10xxxxxx */ {

      if ((s[1] & 0xC0) != 0x80 || (s[2] & 0xC0) != 0x80)

        return 0;

      s += 3;

    } else if ((*s & 0xF8) == 0xF0) /* 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */ {

      if ((s[1] & 0xC0) != 0x80 || (s[2] & 0xC0) != 0x80 || (s[3] & 0xC0) != 0x80)

        return 0;

      s += 4;

    } else

      return 0;

  }

  return 1;

}

char *wget_str_to_utf8(const char *src, const char *encoding)

{

  return wget_striconv(src, encoding, "utf-8");

}

char *wget_utf8_to_str(const char *src, const char *encoding)

{

  return wget_striconv(src, "utf-8", encoding);

}

#ifdef WITH_LIBIDN

/*

 * Work around a libidn <= 1.30 vulnerability.

 *

 * The function checks for a valid UTF-8 character sequence before

 * passing it to idna_to_ascii_8z().

 *

 * [1] https://lists.gnu.org/archive/html/help-libidn/2015-05/msg00002.html

 * [2] https://lists.gnu.org/archive/html/bug-wget/2015-06/msg00002.html

 * [3] https://curl.haxx.se/mail/lib-2015-06/0143.html

 */

static int WGET_GCC_PURE _utf8_is_valid(const char *utf8)

{

  const unsigned char *s = (const unsigned char *) utf8;

  while (*s) {

    if ((*s & 0x80) == 0) /* 0xxxxxxx ASCII char */

      s++;

    else if ((*s & 0xE0) == 0xC0) /* 110xxxxx 10xxxxxx */ {

      if ((s[1] & 0xC0) != 0x80)

        return 0;

      s += 2;

    } else if ((*s & 0xF0) == 0xE0) /* 1110xxxx 10xxxxxx 10xxxxxx */ {

      if ((s[1] & 0xC0) != 0x80 || (s[2] & 0xC0) != 0x80)

        return 0;

      s += 3;

    } else if ((*s & 0xF8) == 0xF0) /* 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */ {

      if ((s[1] & 0xC0) != 0x80 || (s[2] & 0xC0) != 0x80 || (s[3] & 0xC0) != 0x80)

        return 0;

      s += 4;

    } else

      return 0;

  }

  return 1;

}

#endif

/* We convert hostnames and thus have to apply IDN2_USE_STD3_ASCII_RULES.

 * If we don't do, the result could contain any ascii characters,

 * e.g. 'evil.c\u2100.example.com' will be converted into

 * 'evil.ca/c.example.com', which seems no good idea. */

const char *wget_str_to_ascii(const char *src)

{

#ifdef WITH_LIBIDN2

  if (wget_str_needs_encoding(src)) {

    char *asc = NULL;

    int rc;

    if ((rc = idn2_lookup_u8((uint8_t *)src, (uint8_t **)&asc, IDN2_NONTRANSITIONAL|IDN2_USE_STD3_ASCII_RULES)) != IDN2_OK)

      rc = idn2_lookup_u8((uint8_t *)src, (uint8_t **)&asc, IDN2_TRANSITIONAL|IDN2_USE_STD3_ASCII_RULES);

    if (rc == IDN2_OK)

    {

      debug_printf("idn2 '%s' -> '%s'\n", src, asc);

#  ifdef _WIN32

        src = wget_strdup(asc);

        idn2_free(asc);

#  else

        src = asc;

#  endif

    } else

      error_printf(_("toASCII(%s) failed (%d): %s\n"), src, rc, idn2_strerror(rc));

  }

#elif defined WITH_LIBIDN

  if (wget_str_needs_encoding(src)) {

    char *asc = NULL;

    if (_utf8_is_valid(src)) {

      int rc;

      // idna_to_ascii_8z() automatically converts UTF-8 to lowercase

      if ((rc = idna_to_ascii_8z(src, &asc, IDNA_USE_STD3_ASCII_RULES)) == IDNA_SUCCESS) {

        // debug_printf("toASCII '%s' -> '%s'\n", src, asc);

# ifdef _WIN32

        src = wget_strdup(asc);

        idn_free(asc);

# else

        src = asc;

# endif

      } else

        error_printf(_("toASCII failed (%d): %s\n"), rc, idna_strerror(rc));

    }

    else

      error_printf(_("Invalid UTF-8 sequence not converted: '%s'\n"), src);

  }

#else

  if (wget_str_needs_encoding(src)) {

    error_printf(_("toASCII not available: '%s'\n"), src);

  }

#endif

  return src;

}