// Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) All rights reserved.
// SPDX-License-Identifier: Apache-2.0

#include <openssl/asn1.h>

#include <openssl/err.h>
#include <openssl/mem.h>

#include "internal.h"

// UTF8 utilities

// This parses a UTF8 string one character at a time. It is passed a pointer
// to the string and the length of the string. It sets 'value' to the value
// of the current character. It returns the number of characters read or a
// negative error code: -1 = string too short -2 = illegal character -3 =
// subsequent characters not of the form 10xxxxxx -4 = character encoded
// incorrectly (not minimal length).

int UTF8_getc(const unsigned char *str, int len, uint32_t *val) {
  const unsigned char *p;
  uint32_t value;
  int ret;
  if (len <= 0) {
    return 0;
  }
  p = str;

  // Check syntax and work out the encoded value (if correct)
  if ((*p & 0x80) == 0) {
    value = *p++ & 0x7f;
    ret = 1;
  } else if ((*p & 0xe0) == 0xc0) {
    if (len < 2) {
      return -1;
    }
    if ((p[1] & 0xc0) != 0x80) {
      return -3;
    }
    value = (*p++ & 0x1f) << 6;
    value |= *p++ & 0x3f;
    if (value < 0x80) {
      return -4;
    }
    ret = 2;
  } else if ((*p & 0xf0) == 0xe0) {
    if (len < 3) {
      return -1;
    }
    if (((p[1] & 0xc0) != 0x80) || ((p[2] & 0xc0) != 0x80)) {
      return -3;
    }
    value = (*p++ & 0xf) << 12;
    value |= (*p++ & 0x3f) << 6;
    value |= *p++ & 0x3f;
    if (value < 0x800) {
      return -4;
    }
    ret = 3;
  } else if ((*p & 0xf8) == 0xf0) {
    if (len < 4) {
      return -1;
    }
    if (((p[1] & 0xc0) != 0x80) || ((p[2] & 0xc0) != 0x80) ||
        ((p[3] & 0xc0) != 0x80)) {
      return -3;
    }
    value = ((uint32_t)(*p++ & 0x7)) << 18;
    value |= (*p++ & 0x3f) << 12;
    value |= (*p++ & 0x3f) << 6;
    value |= *p++ & 0x3f;
    if (value < 0x10000) {
      return -4;
    }
    ret = 4;
  } else if ((*p & 0xfc) == 0xf8) {
    if (len < 5) {
      return -1;
    }
    if (((p[1] & 0xc0) != 0x80) || ((p[2] & 0xc0) != 0x80) ||
        ((p[3] & 0xc0) != 0x80) || ((p[4] & 0xc0) != 0x80)) {
      return -3;
    }
    value = ((uint32_t)(*p++ & 0x3)) << 24;
    value |= ((uint32_t)(*p++ & 0x3f)) << 18;
    value |= ((uint32_t)(*p++ & 0x3f)) << 12;
    value |= (*p++ & 0x3f) << 6;
    value |= *p++ & 0x3f;
    if (value < 0x200000) {
      return -4;
    }
    ret = 5;
  } else if ((*p & 0xfe) == 0xfc) {
    if (len < 6) {
      return -1;
    }
    if (((p[1] & 0xc0) != 0x80) || ((p[2] & 0xc0) != 0x80) ||
        ((p[3] & 0xc0) != 0x80) || ((p[4] & 0xc0) != 0x80) ||
        ((p[5] & 0xc0) != 0x80)) {
      return -3;
    }
    value = ((uint32_t)(*p++ & 0x1)) << 30;
    value |= ((uint32_t)(*p++ & 0x3f)) << 24;
    value |= ((uint32_t)(*p++ & 0x3f)) << 18;
    value |= ((uint32_t)(*p++ & 0x3f)) << 12;
    value |= (*p++ & 0x3f) << 6;
    value |= *p++ & 0x3f;
    if (value < 0x4000000) {
      return -4;
    }
    ret = 6;
  } else {
    return -2;
  }
  *val = value;
  return ret;
}

// This takes a character 'value' and writes the UTF8 encoded value in 'str'
// where 'str' is a buffer containing 'len' characters. Returns the number of
// characters written or -1 if 'len' is too small. 'str' can be set to NULL
// in which case it just returns the number of characters. It will need at
// most 6 characters.

int UTF8_putc(unsigned char *str, int len, uint32_t value) {
  if (!str) {
    len = 6;  // Maximum we will need
  } else if (len <= 0) {
    return -1;
  }
  if (value < 0x80) {
    if (str) {
      *str = (unsigned char)value;
    }
    return 1;
  }
  if (value < 0x800) {
    if (len < 2) {
      return -1;
    }
    if (str) {
      *str++ = (unsigned char)(((value >> 6) & 0x1f) | 0xc0);
      *str = (unsigned char)((value & 0x3f) | 0x80);
    }
    return 2;
  }
  if (value < 0x10000) {
    if (len < 3) {
      return -1;
    }
    if (str) {
      *str++ = (unsigned char)(((value >> 12) & 0xf) | 0xe0);
      *str++ = (unsigned char)(((value >> 6) & 0x3f) | 0x80);
      *str = (unsigned char)((value & 0x3f) | 0x80);
    }
    return 3;
  }
  if (value < 0x200000) {
    if (len < 4) {
      return -1;
    }
    if (str) {
      *str++ = (unsigned char)(((value >> 18) & 0x7) | 0xf0);
      *str++ = (unsigned char)(((value >> 12) & 0x3f) | 0x80);
      *str++ = (unsigned char)(((value >> 6) & 0x3f) | 0x80);
      *str = (unsigned char)((value & 0x3f) | 0x80);
    }
    return 4;
  }
  if (value < 0x4000000) {
    if (len < 5) {
      return -1;
    }
    if (str) {
      *str++ = (unsigned char)(((value >> 24) & 0x3) | 0xf8);
      *str++ = (unsigned char)(((value >> 18) & 0x3f) | 0x80);
      *str++ = (unsigned char)(((value >> 12) & 0x3f) | 0x80);
      *str++ = (unsigned char)(((value >> 6) & 0x3f) | 0x80);
      *str = (unsigned char)((value & 0x3f) | 0x80);
    }
    return 5;
  }
  if (len < 6) {
    return -1;
  }
  if (str) {
    *str++ = (unsigned char)(((value >> 30) & 0x1) | 0xfc);
    *str++ = (unsigned char)(((value >> 24) & 0x3f) | 0x80);
    *str++ = (unsigned char)(((value >> 18) & 0x3f) | 0x80);
    *str++ = (unsigned char)(((value >> 12) & 0x3f) | 0x80);
    *str++ = (unsigned char)(((value >> 6) & 0x3f) | 0x80);
    *str = (unsigned char)((value & 0x3f) | 0x80);
  }
  return 6;
}