boringssl/crypto/asn1/a_strex.c

/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.] */

#include <openssl/asn1.h>

#include <assert.h>
#include <ctype.h>
#include <inttypes.h>
#include <string.h>

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

#include "internal.h"


#define ESC_FLAGS                                                           \
  (ASN1_STRFLGS_ESC_2253 | ASN1_STRFLGS_ESC_QUOTE | ASN1_STRFLGS_ESC_CTRL | \
   ASN1_STRFLGS_ESC_MSB)

static int maybe_write(BIO *out, const void *buf, int len) {
  /* If |out| is NULL, ignore the output but report the length. */
  return out == NULL || BIO_write(out, buf, len) == len;
}

static int is_control_character(unsigned char c) { return c < 32 || c == 127; }

static int do_esc_char(uint32_t c, unsigned long flags, char *do_quotes,
                       BIO *out, int is_first, int is_last) {
  /* |c| is a |uint32_t| because, depending on |ASN1_STRFLGS_UTF8_CONVERT|,
   * we may be escaping bytes or Unicode codepoints. */
  char buf[16]; /* Large enough for "\\W01234567". */
  unsigned char u8 = (unsigned char)c;
  if (c > 0xffff) {
    BIO_snprintf(buf, sizeof(buf), "\\W%08" PRIX32, c);
  } else if (c > 0xff) {
    BIO_snprintf(buf, sizeof(buf), "\\U%04" PRIX32, c);
  } else if ((flags & ASN1_STRFLGS_ESC_MSB) && c > 0x7f) {
    BIO_snprintf(buf, sizeof(buf), "\\%02X", c);
  } else if ((flags & ASN1_STRFLGS_ESC_CTRL) && is_control_character(c)) {
    BIO_snprintf(buf, sizeof(buf), "\\%02X", c);
  } else if (flags & ASN1_STRFLGS_ESC_2253) {
    /* See RFC 2253, sections 2.4 and 4. */
    if (c == '\\' || c == '"') {
      /* Quotes and backslashes are always escaped, quoted or not. */
      BIO_snprintf(buf, sizeof(buf), "\\%c", (int)c);
    } else if (c == ',' || c == '+' || c == '<' || c == '>' || c == ';' ||
               (is_first && (c == ' ' || c == '#')) ||
               (is_last && (c == ' '))) {
      if (flags & ASN1_STRFLGS_ESC_QUOTE) {
        /* No need to escape, just tell the caller to quote. */
        if (do_quotes != NULL) {
          *do_quotes = 1;
        }
        return maybe_write(out, &u8, 1) ? 1 : -1;
      }
      BIO_snprintf(buf, sizeof(buf), "\\%c", (int)c);
    } else {
      return maybe_write(out, &u8, 1) ? 1 : -1;
    }
  } else if ((flags & ESC_FLAGS) && c == '\\') {
    /* If any escape flags are set, also escape backslashes. */
    BIO_snprintf(buf, sizeof(buf), "\\%c", (int)c);
  } else {
    return maybe_write(out, &u8, 1) ? 1 : -1;
  }

  int len = strlen(buf);
  return maybe_write(out, buf, len) ? len : -1;
}

/*
 * This function sends each character in a buffer to do_esc_char(). It
 * interprets the content formats and converts to or from UTF8 as
 * appropriate.
 */

static int do_buf(const unsigned char *buf, int buflen, int encoding,
                  int utf8_convert, unsigned long flags, char *quotes,
                  BIO *out) {
  /* Reject invalid UCS-4 and UCS-2 lengths without parsing. */
  switch (encoding) {
    case MBSTRING_UNIV:
      if (buflen & 3) {
        OPENSSL_PUT_ERROR(ASN1, ASN1_R_INVALID_UNIVERSALSTRING);
        return -1;
      }
      break;
    case MBSTRING_BMP:
      if (buflen & 1) {
        OPENSSL_PUT_ERROR(ASN1, ASN1_R_INVALID_BMPSTRING);
        return -1;
      }
      break;
  }

  const unsigned char *p = buf;
  const unsigned char *q = buf + buflen;
  int outlen = 0;
  while (p != q) {
    const int is_first = p == buf;
    /* TODO(davidben): Replace this with |cbs_get_ucs2_be|, etc., to check
     * for invalid codepoints. Before doing that, enforce it in the parser,
     * https://crbug.com/boringssl/427, so these error cases are not
     * reachable from parsed objects. */
    uint32_t c;
    switch (encoding) {
      case MBSTRING_UNIV:
        c = ((uint32_t)*p++) << 24;
        c |= ((uint32_t)*p++) << 16;
        c |= ((uint32_t)*p++) << 8;
        c |= *p++;
        break;

      case MBSTRING_BMP:
        c = ((uint32_t)*p++) << 8;
        c |= *p++;
        break;

      case MBSTRING_ASC:
        c = *p++;
        break;

      case MBSTRING_UTF8: {
        int consumed = UTF8_getc(p, buflen, &c);
        if (consumed < 0) {
          return -1; /* Invalid UTF8String */
        }
        buflen -= consumed;
        p += consumed;
        break;
      }

      default:
        assert(0);
        return -1;
    }
    const int is_last = p == q;
    if (utf8_convert) {
      unsigned char utfbuf[6];
      int utflen;
      utflen = UTF8_putc(utfbuf, sizeof utfbuf, c);
      for (int i = 0; i < utflen; i++) {
        /*
         * We don't need to worry about setting orflags correctly
         * because if utflen==1 its value will be correct anyway
         * otherwise each character will be > 0x7f and so the
         * character will never be escaped on first and last.
         */
        int len = do_esc_char(utfbuf[i], flags, quotes, out, is_first, is_last);
        if (len < 0) {
          return -1;
        }
        outlen += len;
      }
    } else {
      int len = do_esc_char(c, flags, quotes, out, is_first, is_last);
      if (len < 0) {
        return -1;
      }
      outlen += len;
    }
  }
  return outlen;
}

/* This function hex dumps a buffer of characters */

static int do_hex_dump(BIO *out, unsigned char *buf, int buflen) {
  static const char hexdig[] = "0123456789ABCDEF";
  unsigned char *p, *q;
  char hextmp[2];
  if (out) {
    p = buf;
    q = buf + buflen;
    while (p != q) {
      hextmp[0] = hexdig[*p >> 4];
      hextmp[1] = hexdig[*p & 0xf];
      if (!maybe_write(out, hextmp, 2)) {
        return -1;
      }
      p++;
    }
  }
  return buflen << 1;
}

/*
 * "dump" a string. This is done when the type is unknown, or the flags
 * request it. We can either dump the content octets or the entire DER
 * encoding. This uses the RFC 2253 #01234 format.
 */

static int do_dump(unsigned long flags, BIO *out, const ASN1_STRING *str) {
  if (!maybe_write(out, "#", 1)) {
    return -1;
  }

  /* If we don't dump DER encoding just dump content octets */
  if (!(flags & ASN1_STRFLGS_DUMP_DER)) {
    int outlen = do_hex_dump(out, str->data, str->length);
    if (outlen < 0) {
      return -1;
    }
    return outlen + 1;
  }

  /*
   * Placing the ASN1_STRING in a temporary ASN1_TYPE allows the DER encoding
   * to readily obtained.
   */
  ASN1_TYPE t;
  t.type = str->type;
  /* Negative INTEGER and ENUMERATED values are the only case where
   * |ASN1_STRING| and |ASN1_TYPE| types do not match.
   *
   * TODO(davidben): There are also some type fields which, in |ASN1_TYPE|, do
   * not correspond to |ASN1_STRING|. It is unclear whether those are allowed
   * in |ASN1_STRING| at all, or what the space of allowed types is.
   * |ASN1_item_ex_d2i| will never produce such a value so, for now, we say
   * this is an invalid input. But this corner of the library in general
   * should be more robust. */
  if (t.type == V_ASN1_NEG_INTEGER) {
    t.type = V_ASN1_INTEGER;
  } else if (t.type == V_ASN1_NEG_ENUMERATED) {
    t.type = V_ASN1_ENUMERATED;
  }
  t.value.asn1_string = (ASN1_STRING *)str;
  unsigned char *der_buf = NULL;
  int der_len = i2d_ASN1_TYPE(&t, &der_buf);
  if (der_len < 0) {
    return -1;
  }
  int outlen = do_hex_dump(out, der_buf, der_len);
  OPENSSL_free(der_buf);
  if (outlen < 0) {
    return -1;
  }
  return outlen + 1;
}

/* string_type_to_encoding returns the |MBSTRING_*| constant for the encoding
 * used by the |ASN1_STRING| type |type|, or -1 if |tag| is not a string
 * type. */
static int string_type_to_encoding(int type) {
  /* This function is sometimes passed ASN.1 universal types and sometimes
   * passed |ASN1_STRING| type values */
  switch (type) {
    case V_ASN1_UTF8STRING:
      return MBSTRING_UTF8;
    case V_ASN1_NUMERICSTRING:
    case V_ASN1_PRINTABLESTRING:
    case V_ASN1_T61STRING:
    case V_ASN1_IA5STRING:
    case V_ASN1_UTCTIME:
    case V_ASN1_GENERALIZEDTIME:
    case V_ASN1_ISO64STRING:
      /* |MBSTRING_ASC| refers to Latin-1, not ASCII. */
      return MBSTRING_ASC;
    case V_ASN1_UNIVERSALSTRING:
      return MBSTRING_UNIV;
    case V_ASN1_BMPSTRING:
      return MBSTRING_BMP;
  }
  return -1;
}

/*
 * This is the main function, print out an ASN1_STRING taking note of various
 * escape and display options. Returns number of characters written or -1 if
 * an error occurred.
 */

int ASN1_STRING_print_ex(BIO *out, const ASN1_STRING *str,
                         unsigned long flags) {
  int type = str->type;
  int outlen = 0;
  if (flags & ASN1_STRFLGS_SHOW_TYPE) {
    const char *tagname = ASN1_tag2str(type);
    outlen += strlen(tagname);
    if (!maybe_write(out, tagname, outlen) || !maybe_write(out, ":", 1)) {
      return -1;
    }
    outlen++;
  }

  /* Decide what to do with |str|, either dump the contents or display it. */
  int encoding;
  if (flags & ASN1_STRFLGS_DUMP_ALL) {
    /* Dump everything. */
    encoding = -1;
  } else if (flags & ASN1_STRFLGS_IGNORE_TYPE) {
    /* Ignore the string type and interpret the contents as Latin-1. */
    encoding = MBSTRING_ASC;
  } else {
    encoding = string_type_to_encoding(type);
    if (encoding == -1 && (flags & ASN1_STRFLGS_DUMP_UNKNOWN) == 0) {
      encoding = MBSTRING_ASC;
    }
  }

  if (encoding == -1) {
    int len = do_dump(flags, out, str);
    if (len < 0) {
      return -1;
    }
    outlen += len;
    return outlen;
  }

  int utf8_convert = 0;
  if (flags & ASN1_STRFLGS_UTF8_CONVERT) {
    /* If the string is UTF-8, skip decoding and just interpret it as 1 byte
     * per character to avoid converting twice.
     *
     * TODO(davidben): This is not quite a valid optimization if the input
     * was invalid UTF-8. */
    if (encoding == MBSTRING_UTF8) {
      encoding = MBSTRING_ASC;
    } else {
      utf8_convert = 1;
    }
  }

  /* Measure the length. */
  char quotes = 0;
  int len = do_buf(str->data, str->length, encoding, utf8_convert, flags,
                   &quotes, NULL);
  if (len < 0) {
    return -1;
  }
  outlen += len;
  if (quotes) {
    outlen += 2;
  }
  if (!out) {
    return outlen;
  }

  /* Encode the value. */
  if ((quotes && !maybe_write(out, "\"", 1)) ||
      do_buf(str->data, str->length, encoding, utf8_convert, flags, NULL, out) <
          0 ||
      (quotes && !maybe_write(out, "\"", 1))) {
    return -1;
  }
  return outlen;
}

int ASN1_STRING_print_ex_fp(FILE *fp, const ASN1_STRING *str,
                            unsigned long flags) {
  BIO *bio = NULL;
  if (fp != NULL) {
    /* If |fp| is NULL, this function returns the number of bytes without
     * writing. */
    bio = BIO_new_fp(fp, BIO_NOCLOSE);
    if (bio == NULL) {
      return -1;
    }
  }
  int ret = ASN1_STRING_print_ex(bio, str, flags);
  BIO_free(bio);
  return ret;
}

int ASN1_STRING_to_UTF8(unsigned char **out, const ASN1_STRING *in) {
  if (!in) {
    return -1;
  }
  int mbflag = string_type_to_encoding(in->type);
  if (mbflag == -1) {
    OPENSSL_PUT_ERROR(ASN1, ASN1_R_UNKNOWN_TAG);
    return -1;
  }
  ASN1_STRING stmp, *str = &stmp;
  stmp.data = NULL;
  stmp.length = 0;
  stmp.flags = 0;
  int ret =
      ASN1_mbstring_copy(&str, in->data, in->length, mbflag, B_ASN1_UTF8STRING);
  if (ret < 0) {
    return ret;
  }
  *out = stmp.data;
  return stmp.length;
}

int ASN1_STRING_print(BIO *bp, const ASN1_STRING *v) {
  int i, n;
  char buf[80];
  const char *p;

  if (v == NULL) {
    return (0);
  }
  n = 0;
  p = (const char *)v->data;
  for (i = 0; i < v->length; i++) {
    if ((p[i] > '~') || ((p[i] < ' ') && (p[i] != '\n') && (p[i] != '\r'))) {
      buf[n] = '.';
    } else {
      buf[n] = p[i];
    }
    n++;
    if (n >= 80) {
      if (BIO_write(bp, buf, n) <= 0) {
        return (0);
      }
      n = 0;
    }
  }
  if (n > 0) {
    if (BIO_write(bp, buf, n) <= 0) {
      return (0);
    }
  }
  return (1);
}

int ASN1_TIME_print(BIO *bp, const ASN1_TIME *tm) {
  if (tm->type == V_ASN1_UTCTIME) {
    return ASN1_UTCTIME_print(bp, tm);
  }
  if (tm->type == V_ASN1_GENERALIZEDTIME) {
    return ASN1_GENERALIZEDTIME_print(bp, tm);
  }
  BIO_write(bp, "Bad time value", 14);
  return (0);
}

static const char *const mon[12] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
                                    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};

int ASN1_GENERALIZEDTIME_print(BIO *bp, const ASN1_GENERALIZEDTIME *tm) {
  char *v;
  int gmt = 0;
  int i;
  int y = 0, M = 0, d = 0, h = 0, m = 0, s = 0;
  char *f = NULL;
  int f_len = 0;

  i = tm->length;
  v = (char *)tm->data;

  if (i < 12) {
    goto err;
  }
  if (v[i - 1] == 'Z') {
    gmt = 1;
  }
  for (i = 0; i < 12; i++) {
    if ((v[i] > '9') || (v[i] < '0')) {
      goto err;
    }
  }
  y = (v[0] - '0') * 1000 + (v[1] - '0') * 100 + (v[2] - '0') * 10 +
      (v[3] - '0');
  M = (v[4] - '0') * 10 + (v[5] - '0');
  if ((M > 12) || (M < 1)) {
    goto err;
  }
  d = (v[6] - '0') * 10 + (v[7] - '0');
  h = (v[8] - '0') * 10 + (v[9] - '0');
  m = (v[10] - '0') * 10 + (v[11] - '0');
  if (tm->length >= 14 && (v[12] >= '0') && (v[12] <= '9') && (v[13] >= '0') &&
      (v[13] <= '9')) {
    s = (v[12] - '0') * 10 + (v[13] - '0');
    /* Check for fractions of seconds. */
    if (tm->length >= 15 && v[14] == '.') {
      int l = tm->length;
      f = &v[14]; /* The decimal point. */
      f_len = 1;
      while (14 + f_len < l && f[f_len] >= '0' && f[f_len] <= '9') {
        ++f_len;
      }
    }
  }

  if (BIO_printf(bp, "%s %2d %02d:%02d:%02d%.*s %d%s", mon[M - 1], d, h, m, s,
                 f_len, f, y, (gmt) ? " GMT" : "") <= 0) {
    return (0);
  } else {
    return (1);
  }
err:
  BIO_write(bp, "Bad time value", 14);
  return (0);
}

// consume_two_digits is a helper function for ASN1_UTCTIME_print. If |*v|,
// assumed to be |*len| bytes long, has two leading digits, updates |*out| with
// their value, updates |v| and |len|, and returns one. Otherwise, returns
// zero.
static int consume_two_digits(int *out, const char **v, int *len) {
  if (*len < 2 || !isdigit((unsigned char)((*v)[0])) ||
      !isdigit((unsigned char)((*v)[1]))) {
    return 0;
  }
  *out = ((*v)[0] - '0') * 10 + ((*v)[1] - '0');
  *len -= 2;
  *v += 2;
  return 1;
}

// consume_zulu_timezone is a helper function for ASN1_UTCTIME_print. If |*v|,
// assumed to be |*len| bytes long, starts with "Z" then it updates |*v| and
// |*len| and returns one. Otherwise returns zero.
static int consume_zulu_timezone(const char **v, int *len) {
  if (*len == 0 || (*v)[0] != 'Z') {
    return 0;
  }

  *len -= 1;
  *v += 1;
  return 1;
}

int ASN1_UTCTIME_print(BIO *bp, const ASN1_UTCTIME *tm) {
  const char *v = (const char *)tm->data;
  int len = tm->length;
  int Y = 0, M = 0, D = 0, h = 0, m = 0, s = 0;

  // YYMMDDhhmm are required to be present.
  if (!consume_two_digits(&Y, &v, &len) || !consume_two_digits(&M, &v, &len) ||
      !consume_two_digits(&D, &v, &len) || !consume_two_digits(&h, &v, &len) ||
      !consume_two_digits(&m, &v, &len)) {
    goto err;
  }
  // https://tools.ietf.org/html/rfc5280, section 4.1.2.5.1, requires seconds
  // to be present, but historically this code has forgiven its absence.
  consume_two_digits(&s, &v, &len);

  // https://tools.ietf.org/html/rfc5280, section 4.1.2.5.1, specifies this
  // interpretation of the year.
  if (Y < 50) {
    Y += 2000;
  } else {
    Y += 1900;
  }
  if (M > 12 || M == 0) {
    goto err;
  }
  if (D > 31 || D == 0) {
    goto err;
  }
  if (h > 23 || m > 59 || s > 60) {
    goto err;
  }

  // https://tools.ietf.org/html/rfc5280, section 4.1.2.5.1, requires the "Z"
  // to be present, but historically this code has forgiven its absence.
  const int is_gmt = consume_zulu_timezone(&v, &len);

  // https://tools.ietf.org/html/rfc5280, section 4.1.2.5.1, does not permit
  // the specification of timezones using the +hhmm / -hhmm syntax, which is
  // the only other thing that might legitimately be found at the end.
  if (len) {
    goto err;
  }

  return BIO_printf(bp, "%s %2d %02d:%02d:%02d %d%s", mon[M - 1], D, h, m, s, Y,
                    is_gmt ? " GMT" : "") > 0;

err:
  BIO_write(bp, "Bad time value", 14);
  return 0;
}