utf8.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2020, Sean Bright
 *
 * Sean Bright <[email protected]>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief UTF-8 information and validation functions
 */

/*** MODULEINFO
    <support_level>core</support_level>
***/

#include "asterisk.h"

#include "asterisk/utils.h"
#include "asterisk/utf8.h"
#include "asterisk/test.h"

/*
 * BEGIN THIRD PARTY CODE
 *
 * Copyright (c) 2008-2010 Björn Höhrmann <[email protected]>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * See http://bjoern.hoehrmann.de/utf-8/decoder/dfa/ for details.
 */

#define UTF8_ACCEPT 0
#define UTF8_REJECT 12

static const uint8_t utf8d[] = {
   /* The first part of the table maps bytes to character classes that
    * to reduce the size of the transition table and create bitmasks. */
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,  0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
   1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,  9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
   7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,  7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
   8,8,2,2,2,2,2,2,2,2,2,2,2,2,2,2,  2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
   10,3,3,3,3,3,3,3,3,3,3,3,3,4,3,3, 11,6,6,6,5,8,8,8,8,8,8,8,8,8,8,8,

   /* The second part is a transition table that maps a combination
    * of a state of the automaton and a character class to a state. */
   0,12,24,36,60,96,84,12,12,12,48,72, 12,12,12,12,12,12,12,12,12,12,12,12,
   12, 0,12,12,12,12,12, 0,12, 0,12,12, 12,24,12,12,12,12,12,24,12,24,12,12,
   12,12,12,12,12,12,12,24,12,12,12,12, 12,24,12,12,12,12,12,12,12,24,12,12,
   12,12,12,12,12,12,12,36,12,36,12,12, 12,36,12,12,12,12,12,36,12,36,12,12,
   12,36,12,12,12,12,12,12,12,12,12,12,
};

#if 0
/* We can bring this back if we need the codepoint? */
static uint32_t inline decode(uint32_t *state, uint32_t *codep, uint32_t byte) {
   uint32_t type = utf8d[byte];

   *codep = (*state != UTF8_ACCEPT) ?
      (byte & 0x3fu) | (*codep << 6) :
      (0xff >> type) & (byte);

   *state = utf8d[256 + *state + type];
   return *state;
}
#endif

static uint32_t inline decode(uint32_t *state, uint32_t byte) {
   uint32_t type = utf8d[byte];
   *state = utf8d[256 + *state + type];
   return *state;
}

/*
 * END THIRD PARTY CODE
 *
 * See copyright notice above.
 */

int ast_utf8_is_valid(const char *src)
{
   uint32_t state = UTF8_ACCEPT;

   while (*src) {
      decode(&state, (uint8_t) *src++);
   }

   return state == UTF8_ACCEPT;
}

int ast_utf8_is_validn(const char *src, size_t size)
{
   uint32_t state = UTF8_ACCEPT;

   while (size && *src) {
      decode(&state, (uint8_t) *src++);
      size--;
   }

   return state == UTF8_ACCEPT;
}

void ast_utf8_copy_string(char *dst, const char *src, size_t size)
{
   uint32_t state = UTF8_ACCEPT;
   char *last_good = dst;

   ast_assert(size > 0);

   while (size && *src) {
      if (decode(&state, (uint8_t) *src) == UTF8_REJECT) {
         /* We _could_ replace with U+FFFD and try to recover, but for now
          * we treat this the same as if we had run out of space */
         break;
      }

      *dst++ = *src++;
      size--;

      if (size && state == UTF8_ACCEPT) {
         /* last_good is where we will ultimately write the 0 byte */
         last_good = dst;
      }
   }

   *last_good = '\0';
}

struct ast_utf8_validator {
   uint32_t state;
};

int ast_utf8_validator_new(struct ast_utf8_validator **validator)
{
   struct ast_utf8_validator *tmp = ast_malloc(sizeof(*tmp));

   if (!tmp) {
      return 1;
   }

   tmp->state = UTF8_ACCEPT;
   *validator = tmp;
   return 0;
}

enum ast_utf8_validation_result ast_utf8_validator_state(
   struct ast_utf8_validator *validator)
{
   switch (validator->state) {
   case UTF8_ACCEPT:
      return AST_UTF8_VALID;
   case UTF8_REJECT:
      return AST_UTF8_INVALID;
   default:
      return AST_UTF8_UNKNOWN;
   }
}

enum ast_utf8_validation_result ast_utf8_validator_feed(
   struct ast_utf8_validator *validator, const char *data)
{
   while (*data) {
      decode(&validator->state, (uint8_t) *data++);
   }

   return ast_utf8_validator_state(validator);
}

enum ast_utf8_validation_result ast_utf8_validator_feedn(
   struct ast_utf8_validator *validator, const char *data, size_t size)
{
   while (size && *data) {
      decode(&validator->state, (uint8_t) *data++);
      size--;
   }

   return ast_utf8_validator_state(validator);
}

void ast_utf8_validator_reset(struct ast_utf8_validator *validator)
{
   validator->state = UTF8_ACCEPT;
}

void ast_utf8_validator_destroy(struct ast_utf8_validator *validator)
{
   ast_free(validator);
}

#ifdef TEST_FRAMEWORK

AST_TEST_DEFINE(test_utf8_is_valid)
{
   switch (cmd) {
   case TEST_INIT:
      info->name = "is_valid";
      info->category = "/main/utf8/";
      info->summary = "Test ast_utf8_is_valid and ast_utf8_is_validn";
      info->description =
         "Tests UTF-8 string validation code.";
      return AST_TEST_NOT_RUN;
   case TEST_EXECUTE:
      break;
   }

   /* Valid UTF-8 */
   ast_test_validate(test, ast_utf8_is_valid("Asterisk"));
   ast_test_validate(test, ast_utf8_is_valid("\xce\xbb"));
   ast_test_validate(test, ast_utf8_is_valid("\xe2\x8a\x9b"));
   ast_test_validate(test, ast_utf8_is_valid("\xf0\x9f\x93\x9e"));

   /* Valid with leading */
   ast_test_validate(test, ast_utf8_is_valid("aaa Asterisk"));
   ast_test_validate(test, ast_utf8_is_valid("aaa \xce\xbb"));
   ast_test_validate(test, ast_utf8_is_valid("aaa \xe2\x8a\x9b"));
   ast_test_validate(test, ast_utf8_is_valid("aaa \xf0\x9f\x93\x9e"));

   /* Valid with trailing */
   ast_test_validate(test, ast_utf8_is_valid("Asterisk aaa"));
   ast_test_validate(test, ast_utf8_is_valid("\xce\xbb aaa"));
   ast_test_validate(test, ast_utf8_is_valid("\xe2\x8a\x9b aaa"));
   ast_test_validate(test, ast_utf8_is_valid("\xf0\x9f\x93\x9e aaa"));

   /* Valid with leading and trailing */
   ast_test_validate(test, ast_utf8_is_valid("aaa Asterisk aaa"));
   ast_test_validate(test, ast_utf8_is_valid("aaa \xce\xbb aaa"));
   ast_test_validate(test, ast_utf8_is_valid("aaa \xe2\x8a\x9b aaa"));
   ast_test_validate(test, ast_utf8_is_valid("aaa \xf0\x9f\x93\x9e aaa"));

   /* Valid if limited by number of bytes */
   ast_test_validate(test, ast_utf8_is_validn("Asterisk" "\xff", strlen("Asterisk")));
   ast_test_validate(test, ast_utf8_is_validn("\xce\xbb" "\xff", strlen("\xce\xbb")));
   ast_test_validate(test, ast_utf8_is_validn("\xe2\x8a\x9b" "\xff", strlen("\xe2\x8a\x9b")));
   ast_test_validate(test, ast_utf8_is_validn("\xf0\x9f\x93\x9e" "\xff", strlen("\xf0\x9f\x93\x9e")));

   /* Invalid */
   ast_test_validate(test, !ast_utf8_is_valid("\xc0\x8a")); /* Overlong */
   ast_test_validate(test, !ast_utf8_is_valid("98.6\xa7")); /* 'High ASCII' */
   ast_test_validate(test, !ast_utf8_is_valid("\xc3\x28"));
   ast_test_validate(test, !ast_utf8_is_valid("\xa0\xa1"));
   ast_test_validate(test, !ast_utf8_is_valid("\xe2\x28\xa1"));
   ast_test_validate(test, !ast_utf8_is_valid("\xe2\x82\x28"));
   ast_test_validate(test, !ast_utf8_is_valid("\xf0\x28\x8c\xbc"));
   ast_test_validate(test, !ast_utf8_is_valid("\xf0\x90\x28\xbc"));
   ast_test_validate(test, !ast_utf8_is_valid("\xf0\x28\x8c\x28"));

   return AST_TEST_PASS;
}

static int test_copy_and_compare(const char *src, size_t dst_len, const char *cmp)
{
   char dst[dst_len];
   ast_utf8_copy_string(dst, src, dst_len);
   return strcmp(dst, cmp) == 0;
}

AST_TEST_DEFINE(test_utf8_copy_string)
{
   switch (cmd) {
   case TEST_INIT:
      info->name = "copy_string";
      info->category = "/main/utf8/";
      info->summary = "Test ast_utf8_copy_string";
      info->description =
         "Tests UTF-8 string copying code.";
      return AST_TEST_NOT_RUN;
   case TEST_EXECUTE:
      break;
   }

   ast_test_validate(test, test_copy_and_compare("Asterisk",           6, "Aster"));
   ast_test_validate(test, test_copy_and_compare("Asterisk \xc2\xae", 11, "Asterisk "));
   ast_test_validate(test, test_copy_and_compare("Asterisk \xc2\xae", 12, "Asterisk \xc2\xae"));
   ast_test_validate(test, test_copy_and_compare("Asterisk \xc0\x8a", 12, "Asterisk "));
   ast_test_validate(test, test_copy_and_compare("\xce\xbb xyz", 1, ""));
   ast_test_validate(test, test_copy_and_compare("\xce\xbb xyz", 2, ""));
   ast_test_validate(test, test_copy_and_compare("\xce\xbb xyz", 3, "\xce\xbb"));
   ast_test_validate(test, test_copy_and_compare("\xce\xbb xyz", 4, "\xce\xbb "));
   ast_test_validate(test, test_copy_and_compare("\xce\xbb xyz", 5, "\xce\xbb x"));
   ast_test_validate(test, test_copy_and_compare("\xce\xbb xyz", 6, "\xce\xbb xy"));
   ast_test_validate(test, test_copy_and_compare("\xce\xbb xyz", 7, "\xce\xbb xyz"));

   return AST_TEST_PASS;
}

AST_TEST_DEFINE(test_utf8_validator)
{
   struct ast_utf8_validator *validator;

   switch (cmd) {
   case TEST_INIT:
      info->name = "utf8_validator";
      info->category = "/main/utf8/";
      info->summary = "Test ast_utf8_validator";
      info->description =
         "Tests UTF-8 progressive validator code.";
      return AST_TEST_NOT_RUN;
   case TEST_EXECUTE:
      break;
   }

   if (ast_utf8_validator_new(&validator)) {
      return AST_TEST_FAIL;
   }

   ast_test_validate(test, ast_utf8_validator_feed(validator, "Asterisk") == AST_UTF8_VALID);
   ast_test_validate(test, ast_utf8_validator_feed(validator, "\xc2")     == AST_UTF8_UNKNOWN);
   ast_test_validate(test, ast_utf8_validator_feed(validator, "\xae")     == AST_UTF8_VALID);
   ast_test_validate(test, ast_utf8_validator_feed(validator, "Private")  == AST_UTF8_VALID);
   ast_test_validate(test, ast_utf8_validator_feed(validator, "Branch")   == AST_UTF8_VALID);
   ast_test_validate(test, ast_utf8_validator_feed(validator, "Exchange") == AST_UTF8_VALID);
   ast_test_validate(test, ast_utf8_validator_feed(validator, "\xe2")     == AST_UTF8_UNKNOWN);
   ast_test_validate(test, ast_utf8_validator_feed(validator, "\x84")     == AST_UTF8_UNKNOWN);
   ast_test_validate(test, ast_utf8_validator_feed(validator, "\xbb")     == AST_UTF8_VALID);
   ast_test_validate(test, ast_utf8_validator_feed(validator, "\xc0\x8a") == AST_UTF8_INVALID);
   ast_test_validate(test, ast_utf8_validator_feed(validator, "valid")    == AST_UTF8_INVALID);
   ast_test_validate(test, ast_utf8_validator_feed(validator, "valid")    == AST_UTF8_INVALID);
   ast_test_validate(test, ast_utf8_validator_feed(validator, "valid")    == AST_UTF8_INVALID);

   ast_utf8_validator_destroy(validator);

   return AST_TEST_PASS;
}

static void test_utf8_shutdown(void)
{
   AST_TEST_UNREGISTER(test_utf8_is_valid);
   AST_TEST_UNREGISTER(test_utf8_copy_string);
   AST_TEST_UNREGISTER(test_utf8_validator);
}

int ast_utf8_init(void)
{
   AST_TEST_REGISTER(test_utf8_is_valid);
   AST_TEST_REGISTER(test_utf8_copy_string);
   AST_TEST_REGISTER(test_utf8_validator);

   ast_register_cleanup(test_utf8_shutdown);

   return 0;
}

#else /* !TEST_FRAMEWORK */

int ast_utf8_init(void)
{
   return 0;
}

#endif