idna.c

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#include "config.h"
#include <stdint.h>
#include <stdio.h>
#include "mutt/lib.h"
#include "config/lib.h"
#include "core/lib.h"
#include "idna2.h"
#ifdef HAVE_LIBIDN
#include <stdbool.h>
#include <string.h>
#endif
#ifdef HAVE_STRINGPREP_H
#include <stringprep.h>
#elif defined(HAVE_IDN_STRINGPREP_H)
#include <idn/stringprep.h>
#endif
#define IDN2_SKIP_LIBIDN_COMPAT
#ifdef HAVE_IDN2_H
#include <idn2.h>
#elif defined(HAVE_IDN_IDN2_H)
#include <idn/idn2.h>
#elif defined(HAVE_IDNA_H)
#include <idna.h>
#elif defined(HAVE_IDN_IDNA_H)
#include <idn/idna.h>
#endif

#if defined(HAVE_IDN2_H) || defined(HAVE_IDN_IDN2_H)
#define IDN_VERSION 2
#elif defined(HAVE_IDNA_H) || defined(HAVE_IDN_IDNA_H)
#define IDN_VERSION 1
#endif

#ifdef HAVE_LIBIDN
/* Work around incompatibilities in the libidn API */
#if (!defined(HAVE_IDNA_TO_ASCII_8Z) && defined(HAVE_IDNA_TO_ASCII_FROM_UTF8))
#define idna_to_ascii_8z(input, output, flags)                                 \
  idna_to_ascii_from_utf8(input, output, (flags) &1, ((flags) &2) ? 1 : 0)
#endif
#if (!defined(HAVE_IDNA_TO_ASCII_LZ) && defined(HAVE_IDNA_TO_ASCII_FROM_LOCALE))
#define idna_to_ascii_lz(input, output, flags)                                 \
  idna_to_ascii_from_locale(input, output, (flags) &1, ((flags) &2) ? 1 : 0)
#endif
#if (!defined(HAVE_IDNA_TO_UNICODE_8Z8Z) && defined(HAVE_IDNA_TO_UNICODE_UTF8_FROM_UTF8))
#define idna_to_unicode_8z8z(input, output, flags)                             \
  idna_to_unicode_utf8_from_utf8(input, output, (flags) &1, ((flags) &2) ? 1 : 0)
#endif
#endif /* HAVE_LIBIDN */

#ifdef HAVE_LIBIDN

static bool check_idn(char *domain)
{
  if (!domain)
    return false;

  if (mutt_istr_startswith(domain, "xn--"))
    return true;

  while ((domain = strchr(domain, '.')))
  {
    if (mutt_istr_startswith(++domain, "xn--"))
      return true;
  }

  return false;
}

int mutt_idna_to_ascii_lz(const char *input, char **output, uint8_t flags)
{
  if (!input || !output)
    return 1;

#if (IDN_VERSION == 2)
  return idn2_to_ascii_8z(input, output, flags | IDN2_NFC_INPUT | IDN2_NONTRANSITIONAL);
#else
  return idna_to_ascii_lz(input, output, flags);
#endif
}
#endif /* HAVE_LIBIDN */

char *mutt_idna_intl_to_local(const char *user, const char *domain, uint8_t flags)
{
  char *mailbox = NULL;
  char *reversed_user = NULL, *reversed_domain = NULL;
  char *tmp = NULL;

  char *local_user = mutt_str_dup(user);
  char *local_domain = mutt_str_dup(domain);

#ifdef HAVE_LIBIDN
  bool is_idn_encoded = check_idn(local_domain);
  const bool c_idn_decode = cs_subset_bool(NeoMutt->sub, "idn_decode");
  if (is_idn_encoded && c_idn_decode)
  {
#if (IDN_VERSION == 2)
    if (idn2_to_unicode_8z8z(local_domain, &tmp, IDN2_ALLOW_UNASSIGNED) != IDN2_OK)
#else
    if (idna_to_unicode_8z8z(local_domain, &tmp, IDNA_ALLOW_UNASSIGNED) != IDNA_SUCCESS)
#endif
    {
      goto cleanup;
    }
    mutt_str_replace(&local_domain, tmp);
    FREE(&tmp);
  }
#endif /* HAVE_LIBIDN */

  /* we don't want charset-hook effects, so we set flags to 0 */
  const char *const c_charset = cs_subset_string(NeoMutt->sub, "charset");
  if (mutt_ch_convert_string(&local_user, "utf-8", c_charset, MUTT_ICONV_NO_FLAGS) != 0)
    goto cleanup;

  if (mutt_ch_convert_string(&local_domain, "utf-8", c_charset, MUTT_ICONV_NO_FLAGS) != 0)
    goto cleanup;

  /* make sure that we can convert back and come out with the same
   * user and domain name.  */
  if ((flags & MI_MAY_BE_IRREVERSIBLE) == 0)
  {
    reversed_user = mutt_str_dup(local_user);

    if (mutt_ch_convert_string(&reversed_user, c_charset, "utf-8", MUTT_ICONV_NO_FLAGS) != 0)
    {
      mutt_debug(LL_DEBUG1, "Not reversible. Charset conv to utf-8 failed for user = '%s'\n",
                 reversed_user);
      goto cleanup;
    }

    if (!mutt_istr_equal(user, reversed_user))
    {
      mutt_debug(LL_DEBUG1, "#1 Not reversible. orig = '%s', reversed = '%s'\n",
                 user, reversed_user);
      goto cleanup;
    }

    reversed_domain = mutt_str_dup(local_domain);

    if (mutt_ch_convert_string(&reversed_domain, c_charset, "utf-8", MUTT_ICONV_NO_FLAGS) != 0)
    {
      mutt_debug(LL_DEBUG1, "Not reversible. Charset conv to utf-8 failed for domain = '%s'\n",
                 reversed_domain);
      goto cleanup;
    }

#ifdef HAVE_LIBIDN
    /* If the original domain was UTF-8, idna encoding here could
     * produce a non-matching domain!  Thus we only want to do the
     * idna_to_ascii_8z() if the original domain was IDNA encoded.  */
    if (is_idn_encoded && c_idn_decode)
    {
#if (IDN_VERSION == 2)
      if (idn2_to_ascii_8z(reversed_domain, &tmp,
                           IDN2_ALLOW_UNASSIGNED | IDN2_NFC_INPUT | IDN2_NONTRANSITIONAL) != IDN2_OK)
#else
      if (idna_to_ascii_8z(reversed_domain, &tmp, IDNA_ALLOW_UNASSIGNED) != IDNA_SUCCESS)
#endif
      {
        mutt_debug(LL_DEBUG1, "Not reversible. idna_to_ascii_8z failed for domain = '%s'\n",
                   reversed_domain);
        goto cleanup;
      }
      mutt_str_replace(&reversed_domain, tmp);
    }
#endif /* HAVE_LIBIDN */

    if (!mutt_istr_equal(domain, reversed_domain))
    {
      mutt_debug(LL_DEBUG1, "#2 Not reversible. orig = '%s', reversed = '%s'\n",
                 domain, reversed_domain);
      goto cleanup;
    }
  }

  mailbox = mutt_mem_malloc(mutt_str_len(local_user) + mutt_str_len(local_domain) + 2);
  sprintf(mailbox, "%s@%s", NONULL(local_user), NONULL(local_domain));

cleanup:
  FREE(&local_user);
  FREE(&local_domain);
  FREE(&tmp);
  FREE(&reversed_domain);
  FREE(&reversed_user);

  return mailbox;
}

char *mutt_idna_local_to_intl(const char *user, const char *domain)
{
  char *mailbox = NULL;
  char *tmp = NULL;

  char *intl_user = mutt_str_dup(user);
  char *intl_domain = mutt_str_dup(domain);

  /* we don't want charset-hook effects, so we set flags to 0 */
  const char *const c_charset = cs_subset_string(NeoMutt->sub, "charset");
  if (mutt_ch_convert_string(&intl_user, c_charset, "utf-8", MUTT_ICONV_NO_FLAGS) != 0)
    goto cleanup;

  if (mutt_ch_convert_string(&intl_domain, c_charset, "utf-8", MUTT_ICONV_NO_FLAGS) != 0)
    goto cleanup;

#ifdef HAVE_LIBIDN
  const bool c_idn_encode = cs_subset_bool(NeoMutt->sub, "idn_encode");
  if (c_idn_encode)
  {
#if (IDN_VERSION == 2)
    if (idn2_to_ascii_8z(intl_domain, &tmp,
                         IDN2_ALLOW_UNASSIGNED | IDN2_NFC_INPUT | IDN2_NONTRANSITIONAL) != IDN2_OK)
#else
    if (idna_to_ascii_8z(intl_domain, &tmp, IDNA_ALLOW_UNASSIGNED) != IDNA_SUCCESS)
#endif
    {
      goto cleanup;
    }
    mutt_str_replace(&intl_domain, tmp);
  }
#endif /* HAVE_LIBIDN */

  mailbox = mutt_mem_malloc(mutt_str_len(intl_user) + mutt_str_len(intl_domain) + 2);
  sprintf(mailbox, "%s@%s", NONULL(intl_user), NONULL(intl_domain));

cleanup:
  FREE(&intl_user);
  FREE(&intl_domain);
  FREE(&tmp);

  return mailbox;
}

const char *mutt_idna_print_version(void)
{
  static char vstring[256];

#ifdef HAVE_LIBIDN
#if (IDN_VERSION == 2)
  snprintf(vstring, sizeof(vstring), "libidn2: %s (compiled with %s)",
           idn2_check_version(NULL), IDN2_VERSION);
#elif (IDN_VERSION == 1)
  snprintf(vstring, sizeof(vstring), "libidn: %s (compiled with %s)",
           stringprep_check_version(NULL), STRINGPREP_VERSION);
#endif
#endif /* HAVE_LIBIDN */

  return vstring;
}