/*

 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")

 *

 * SPDX-License-Identifier: MPL-2.0

 *

 * This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, you can obtain one at https://mozilla.org/MPL/2.0/.

 *

 * See the COPYRIGHT file distributed with this work for additional

 * information regarding copyright ownership.

 */

/*! \file */

#include <stdbool.h>

#include <isc/buffer.h>

#include <isc/hex.h>

#include <isc/lex.h>

#include <isc/string.h>

#include <isc/util.h>

#define D ('0' - 0x0) /* ascii '0' to hex */

#define U ('A' - 0xA) /* ascii 'A' to hex */

#define L ('a' - 0xa) /* ascii 'a' to hex */

const uint8_t isc__hex_char[256] = {

  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, D, D, D, D, D, D, D, D, D, D, 0, 0, 0, 0, 0, 0, 0, U,

  U, U, U, U, U, 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, L, L, L, L, L, L, 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

};

#undef D

#undef U

#undef L

#define RETERR(x)                        \

  do {                             \

    isc_result_t _r = (x);   \

    if (_r != ISC_R_SUCCESS) \

      return ((_r));   \

  } while (0)

/*

 * BEW: These static functions are copied from lib/dns/rdata.c.

 */

static isc_result_t

str_totext(const char *source, isc_buffer_t *target);

static isc_result_t

mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length);

static const char hex[] = "0123456789ABCDEF";

isc_result_t

isc_hex_totext(isc_region_t *source, int wordlength, const char *wordbreak,

         isc_buffer_t *target) {

  char buf[3];

  unsigned int loops = 0;

  if (wordlength < 2) {

    wordlength = 2;

  }

  memset(buf, 0, sizeof(buf));

  while (source->length > 0) {

    buf[0] = hex[(source->base[0] >> 4) & 0xf];

    buf[1] = hex[(source->base[0]) & 0xf];

    RETERR(str_totext(buf, target));

    isc_region_consume(source, 1);

    loops++;

    if (source->length != 0 && (int)((loops + 1) * 2) >= wordlength)

    {

      loops = 0;

      RETERR(str_totext(wordbreak, target));

    }

  }

  return ISC_R_SUCCESS;

}

/*%

 * State of a hex decoding process in progress.

 */

typedef struct {

  int length;       /*%< Desired length of binary data or -1 */

  isc_buffer_t *target; /*%< Buffer for resulting binary data */

  int digits;       /*%< Number of buffered hex digits */

  int val[2];

} hex_decode_ctx_t;

static void

hex_decode_init(hex_decode_ctx_t *ctx, int length, isc_buffer_t *target) {

  ctx->digits = 0;

  ctx->length = length;

  ctx->target = target;

}

static isc_result_t

hex_decode_char(hex_decode_ctx_t *ctx, int c) {

  uint8_t hexval;

  hexval = isc_hex_char(c);

  if (hexval == 0) {

    return ISC_R_BADHEX;

  }

  ctx->val[ctx->digits++] = c - hexval;

  if (ctx->digits == 2) {

    unsigned char num;

    num = (ctx->val[0] << 4) + (ctx->val[1]);

    RETERR(mem_tobuffer(ctx->target, &num, 1));

    if (ctx->length >= 0) {

      if (ctx->length == 0) {

        return ISC_R_BADHEX;

      } else {

        ctx->length -= 1;

      }

    }

    ctx->digits = 0;

  }

  return ISC_R_SUCCESS;

}

static isc_result_t

hex_decode_finish(hex_decode_ctx_t *ctx) {

  if (ctx->length > 0) {

    return ISC_R_UNEXPECTEDEND;

  }

  if (ctx->digits != 0) {

    return ISC_R_BADHEX;

  }

  return ISC_R_SUCCESS;

}

isc_result_t

isc_hex_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {

  unsigned int before, after;

  hex_decode_ctx_t ctx;

  isc_textregion_t *tr;

  isc_token_t token;

  bool eol;

  REQUIRE(length >= -2);

  hex_decode_init(&ctx, length, target);

  before = isc_buffer_usedlength(target);

  while (ctx.length != 0) {

    unsigned int i;

    if (length > 0) {

      eol = false;

    } else {

      eol = true;

    }

    RETERR(isc_lex_getmastertoken(lexer, &token,

                isc_tokentype_string, eol));

    if (token.type != isc_tokentype_string) {

      break;

    }

    tr = &token.value.as_textregion;

    for (i = 0; i < tr->length; i++) {

      RETERR(hex_decode_char(&ctx, tr->base[i]));

    }

  }

  after = isc_buffer_usedlength(target);

  if (ctx.length < 0) {

    isc_lex_ungettoken(lexer, &token);

  }

  RETERR(hex_decode_finish(&ctx));

  if (length == -2 && before == after) {

    return ISC_R_UNEXPECTEDEND;

  }

  return ISC_R_SUCCESS;

}

isc_result_t

isc_hex_decodestring(const char *cstr, isc_buffer_t *target) {

  hex_decode_ctx_t ctx;

  hex_decode_init(&ctx, -1, target);

  for (;;) {

    int c = *cstr++;

    if (c == '\0') {

      break;

    }

    if (c == ' ' || c == '\t' || c == '\n' || c == '\r') {

      continue;

    }

    RETERR(hex_decode_char(&ctx, c));

  }

  RETERR(hex_decode_finish(&ctx));

  return ISC_R_SUCCESS;

}

static isc_result_t

str_totext(const char *source, isc_buffer_t *target) {

  unsigned int l;

  isc_region_t region;

  isc_buffer_availableregion(target, &region);

  l = strlen(source);

  if (l > region.length) {

    return ISC_R_NOSPACE;

  }

  memmove(region.base, source, l);

  isc_buffer_add(target, l);

  return ISC_R_SUCCESS;

}

static isc_result_t

mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length) {

  isc_region_t tr;

  isc_buffer_availableregion(target, &tr);

  if (length > tr.length) {

    return ISC_R_NOSPACE;

  }

  memmove(tr.base, base, length);

  isc_buffer_add(target, length);

  return ISC_R_SUCCESS;

}