/*

 * 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/base32.h>

#include <isc/buffer.h>

#include <isc/lex.h>

#include <isc/region.h>

#include <isc/string.h>

#include <isc/util.h>

/*@{*/

/*!

 * These static functions are also present in lib/dns/rdata.c.  I'm not

 * sure where they should go. -- bwelling

 */

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 base32[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567="

           "abcdefghijklmnopqrstuvwxyz234567";

static const char base32hex[] = "0123456789ABCDEFGHIJKLMNOPQRSTUV="

        "0123456789abcdefghijklmnopqrstuv";

static isc_result_t

base32_totext(isc_region_t *source, int wordlength, const char *wordbreak,

        isc_buffer_t *target, const char base[], char pad) {

  char buf[9];

  unsigned int loops = 0;

  if (wordlength >= 0 && wordlength < 8) {

    wordlength = 8;

  }

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

  while (source->length > 0) {

    buf[0] = base[((source->base[0] >> 3) & 0x1f)]; /* 5 + */

    if (source->length == 1) {

      buf[1] = base[(source->base[0] << 2) & 0x1c];

      buf[2] = buf[3] = buf[4] = pad;

      buf[5] = buf[6] = buf[7] = pad;

      RETERR(str_totext(buf, target));

      break;

    }

    buf[1] = base[((source->base[0] << 2) & 0x1c) | /* 3 = 8 */

            ((source->base[1] >> 6) & 0x03)]; /* 2 + */

    buf[2] = base[((source->base[1] >> 1) & 0x1f)]; /* 5 + */

    if (source->length == 2) {

      buf[3] = base[(source->base[1] << 4) & 0x10];

      buf[4] = buf[5] = buf[6] = buf[7] = pad;

      RETERR(str_totext(buf, target));

      break;

    }

    buf[3] = base[((source->base[1] << 4) & 0x10) | /* 1 = 8 */

            ((source->base[2] >> 4) & 0x0f)]; /* 4 + */

    if (source->length == 3) {

      buf[4] = base[(source->base[2] << 1) & 0x1e];

      buf[5] = buf[6] = buf[7] = pad;

      RETERR(str_totext(buf, target));

      break;

    }

    buf[4] = base[((source->base[2] << 1) & 0x1e) | /* 4 = 8 */

            ((source->base[3] >> 7) & 0x01)]; /* 1 + */

    buf[5] = base[((source->base[3] >> 2) & 0x1f)]; /* 5 + */

    if (source->length == 4) {

      buf[6] = base[(source->base[3] << 3) & 0x18];

      buf[7] = pad;

      RETERR(str_totext(buf, target));

      break;

    }

    buf[6] = base[((source->base[3] << 3) & 0x18) | /* 2 = 8 */

            ((source->base[4] >> 5) & 0x07)]; /* 3 + */

    buf[7] = base[source->base[4] & 0x1f];    /* 5 = 8 */

    RETERR(str_totext(buf, target));

    isc_region_consume(source, 5);

    loops++;

    if (source->length != 0 && wordlength >= 0 &&

        (int)((loops + 1) * 8) >= wordlength)

    {

      loops = 0;

      RETERR(str_totext(wordbreak, target));

    }

  }

  if (source->length > 0) {

    isc_region_consume(source, source->length);

  }

  return ISC_R_SUCCESS;

}

isc_result_t

isc_base32_totext(isc_region_t *source, int wordlength, const char *wordbreak,

      isc_buffer_t *target) {

  return base32_totext(source, wordlength, wordbreak, target, base32,

           '=');

}

isc_result_t

isc_base32hex_totext(isc_region_t *source, int wordlength,

         const char *wordbreak, isc_buffer_t *target) {

  return base32_totext(source, wordlength, wordbreak, target, base32hex,

           '=');

}

isc_result_t

isc_base32hexnp_totext(isc_region_t *source, int wordlength,

           const char *wordbreak, isc_buffer_t *target) {

  return base32_totext(source, wordlength, wordbreak, target, base32hex,

           0);

}

/*%

 * State of a base32 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 base32 digits */

  bool seen_end;        /*%< True if "=" end marker seen */

  int val[8];

  const char *base; /*%< Which encoding we are using */

  int seen_32;    /*%< Number of significant bytes if non

         * zero */

  bool pad;   /*%< Expect padding */

} base32_decode_ctx_t;

static isc_result_t

base32_decode_char(base32_decode_ctx_t *ctx, int c) {

  const char *s;

  unsigned int last;

  if (ctx->seen_end) {

    return ISC_R_BADBASE32;

  }

  if ((s = strchr(ctx->base, c)) == NULL) {

    return ISC_R_BADBASE32;

  }

  last = (unsigned int)(s - ctx->base);

  /*

   * Handle lower case.

   */

  if (last > 32) {

    last -= 33;

  }

  /*

   * Check that padding is contiguous.

   */

  if (last != 32 && ctx->seen_32 != 0) {

    return ISC_R_BADBASE32;

  }

  /*

   * If padding is not permitted flag padding as a error.

   */

  if (last == 32 && !ctx->pad) {

    return ISC_R_BADBASE32;

  }

  /*

   * Check that padding starts at the right place and that

   * bits that should be zero are.

   * Record how many significant bytes in answer (seen_32).

   */

  if (last == 32 && ctx->seen_32 == 0) {

    switch (ctx->digits) {

    case 0:

    case 1:

      return ISC_R_BADBASE32;

    case 2:

      if ((ctx->val[1] & 0x03) != 0) {

        return ISC_R_BADBASE32;

      }

      ctx->seen_32 = 1;

      break;

    case 3:

      return ISC_R_BADBASE32;

    case 4:

      if ((ctx->val[3] & 0x0f) != 0) {

        return ISC_R_BADBASE32;

      }

      ctx->seen_32 = 2;

      break;

    case 5:

      if ((ctx->val[4] & 0x01) != 0) {

        return ISC_R_BADBASE32;

      }

      ctx->seen_32 = 3;

      break;

    case 6:

      return ISC_R_BADBASE32;

    case 7:

      if ((ctx->val[6] & 0x07) != 0) {

        return ISC_R_BADBASE32;

      }

      ctx->seen_32 = 4;

      break;

    }

  }

  /*

   * Zero fill pad values.

   */

  ctx->val[ctx->digits++] = (last == 32) ? 0 : last;

  if (ctx->digits == 8) {

    int n = 5;

    unsigned char buf[5];

    if (ctx->seen_32 != 0) {

      ctx->seen_end = true;

      n = ctx->seen_32;

    }

    buf[0] = (ctx->val[0] << 3) | (ctx->val[1] >> 2);

    buf[1] = (ctx->val[1] << 6) | (ctx->val[2] << 1) |

       (ctx->val[3] >> 4);

    buf[2] = (ctx->val[3] << 4) | (ctx->val[4] >> 1);

    buf[3] = (ctx->val[4] << 7) | (ctx->val[5] << 2) |

       (ctx->val[6] >> 3);

    buf[4] = (ctx->val[6] << 5) | (ctx->val[7]);

    RETERR(mem_tobuffer(ctx->target, buf, n));

    if (ctx->length >= 0) {

      if (n > ctx->length) {

        return ISC_R_BADBASE32;

      } else {

        ctx->length -= n;

      }

    }

    ctx->digits = 0;

  }

  return ISC_R_SUCCESS;

}

static isc_result_t

base32_decode_finish(base32_decode_ctx_t *ctx) {

  if (ctx->length > 0) {

    return ISC_R_UNEXPECTEDEND;

  }

  /*

   * Add missing padding if required.

   */

  if (!ctx->pad && ctx->digits != 0) {

    ctx->pad = true;

    do {

      RETERR(base32_decode_char(ctx, '='));

    } while (ctx->digits != 0);

  }

  if (ctx->digits != 0) {

    return ISC_R_BADBASE32;

  }

  return ISC_R_SUCCESS;

}

static isc_result_t

base32_tobuffer(isc_lex_t *lexer, const char base[], bool pad,

    isc_buffer_t *target, int length) {

  unsigned int before, after;

  base32_decode_ctx_t ctx = {

    .length = length, .base = base, .target = target, .pad = pad

  };

  isc_textregion_t *tr;

  isc_token_t token;

  bool eol;

  REQUIRE(length >= -2);

  before = isc_buffer_usedlength(target);

  while (!ctx.seen_end && (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(base32_decode_char(&ctx, tr->base[i]));

    }

  }

  after = isc_buffer_usedlength(target);

  if (ctx.length < 0 && !ctx.seen_end) {

    isc_lex_ungettoken(lexer, &token);

  }

  RETERR(base32_decode_finish(&ctx));

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

    return ISC_R_UNEXPECTEDEND;

  }

  return ISC_R_SUCCESS;

}

isc_result_t

isc_base32_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {

  return base32_tobuffer(lexer, base32, true, target, length);

}

isc_result_t

isc_base32hex_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {

  return base32_tobuffer(lexer, base32hex, true, target, length);

}

isc_result_t

isc_base32hexnp_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {

  return base32_tobuffer(lexer, base32hex, false, target, length);

}

static isc_result_t

base32_decodestring(const char *cstr, const char base[], bool pad,

        isc_buffer_t *target) {

  base32_decode_ctx_t ctx = {

    .length = -1, .base = base, .target = target, .pad = pad

  };

  for (;;) {

    int c = *cstr++;

    if (c == '\0') {

      break;

    }

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

      continue;

    }

    RETERR(base32_decode_char(&ctx, c));

  }

  RETERR(base32_decode_finish(&ctx));

  return ISC_R_SUCCESS;

}

isc_result_t

isc_base32_decodestring(const char *cstr, isc_buffer_t *target) {

  return base32_decodestring(cstr, base32, true, target);

}

isc_result_t

isc_base32hex_decodestring(const char *cstr, isc_buffer_t *target) {

  return base32_decodestring(cstr, base32hex, true, target);

}

isc_result_t

isc_base32hexnp_decodestring(const char *cstr, isc_buffer_t *target) {

  return base32_decodestring(cstr, base32hex, false, target);

}

static isc_result_t

base32_decoderegion(isc_region_t *source, const char base[], bool pad,

        isc_buffer_t *target) {

  base32_decode_ctx_t ctx = {

    .length = -1, .base = base, .target = target, .pad = pad

  };

  while (source->length != 0) {

    int c = *source->base;

    RETERR(base32_decode_char(&ctx, c));

    isc_region_consume(source, 1);

  }

  RETERR(base32_decode_finish(&ctx));

  return ISC_R_SUCCESS;

}

isc_result_t

isc_base32_decoderegion(isc_region_t *source, isc_buffer_t *target) {

  return base32_decoderegion(source, base32, true, target);

}

isc_result_t

isc_base32hex_decoderegion(isc_region_t *source, isc_buffer_t *target) {

  return base32_decoderegion(source, base32hex, true, target);

}

isc_result_t

isc_base32hexnp_decoderegion(isc_region_t *source, isc_buffer_t *target) {

  return base32_decoderegion(source, base32hex, false, target);

}

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;

}