// Copyright 1999-2016 The OpenSSL Project Authors. All Rights Reserved.

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//     https://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

#include <openssl/asn1.h>

#include <openssl/posix_time.h>

#include <assert.h>

#include <stdio.h>

#include <string.h>

#include <time.h>

#include <openssl/asn1t.h>

#include <openssl/bytestring.h>

#include <openssl/err.h>

#include <openssl/mem.h>

#include "internal.h"

using namespace bssl;

// This is an implementation of the ASN1 Time structure which is: Time ::=

// CHOICE { utcTime UTCTime, generalTime GeneralizedTime } written by Steve

// Henson.

BSSL_NAMESPACE_BEGIN

IMPLEMENT_ASN1_MSTRING(ASN1_TIME, B_ASN1_TIME)

BSSL_NAMESPACE_END

IMPLEMENT_ASN1_FUNCTIONS_const(ASN1_TIME)

ASN1_TIME *ASN1_TIME_set_posix(ASN1_TIME *s, int64_t posix_time) {

  return ASN1_TIME_adj(s, posix_time, 0, 0);

}

ASN1_TIME *ASN1_TIME_set(ASN1_TIME *s, time_t time) {

  return ASN1_TIME_adj(s, time, 0, 0);

}

static int fits_in_utc_time(const struct tm *tm) {

  return 50 <= tm->tm_year && tm->tm_year < 150;

}

ASN1_TIME *ASN1_TIME_adj(ASN1_TIME *s, int64_t posix_time, int offset_day,

                         long offset_sec) {

  struct tm tm;

  if (!OPENSSL_posix_to_tm(posix_time, &tm)) {

    OPENSSL_PUT_ERROR(ASN1, ASN1_R_ERROR_GETTING_TIME);

    return nullptr;

  }

  if (offset_day || offset_sec) {

    if (!OPENSSL_gmtime_adj(&tm, offset_day, offset_sec)) {

      return nullptr;

    }

  }

  if (fits_in_utc_time(&tm)) {

    return ASN1_UTCTIME_adj(s, posix_time, offset_day, offset_sec);

  }

  return ASN1_GENERALIZEDTIME_adj(s, posix_time, offset_day, offset_sec);

}

int ASN1_TIME_check(const ASN1_TIME *t) {

  if (t->type == V_ASN1_GENERALIZEDTIME) {

    return ASN1_GENERALIZEDTIME_check(t);

  } else if (t->type == V_ASN1_UTCTIME) {

    return ASN1_UTCTIME_check(t);

  }

  return 0;

}

// Convert an ASN1_TIME structure to GeneralizedTime

ASN1_GENERALIZEDTIME *ASN1_TIME_to_generalizedtime(const ASN1_TIME *in,

                                                   ASN1_GENERALIZEDTIME **out) {

  if (!ASN1_TIME_check(in)) {

    return nullptr;

  }

  UniquePtr<ASN1_GENERALIZEDTIME> tmp;

  ASN1_GENERALIZEDTIME *ret = nullptr;

  if (!out || !*out) {

    tmp.reset(ASN1_GENERALIZEDTIME_new());

    if (tmp == nullptr) {

      return nullptr;

    }

    ret = tmp.get();

  } else {

    ret = *out;

  }

  // If already GeneralizedTime just copy across

  if (in->type == V_ASN1_GENERALIZEDTIME) {

    if (!ASN1_STRING_set(ret, in->data, in->length)) {

      return nullptr;

    }

  } else {

    assert(in->type == V_ASN1_UTCTIME);

    // `ASN1_TIME_check` implies a bound on the string's lengths. In particular,

    // the longest possible UTCTime is "YYMMDDHHMMSS+HHMM", with the (invalid)

    // timezone offsets.

    static constexpr size_t kMaxUTCTimeLength = 17;

    BSSL_CHECK(in->length > 0 &&

               static_cast<size_t>(in->length) <= kMaxUTCTimeLength);

    char buf[2 /* century */ + kMaxUTCTimeLength + 1 /* NUL */];

    // Work out the century and prepend.

    if (in->data[0] >= '5') {

      snprintf(buf, sizeof(buf), "19%.*s", in->length,

               reinterpret_cast<const char *>(in->data));

    } else {

      snprintf(buf, sizeof(buf), "20%.*s", in->length,

               reinterpret_cast<const char *>(in->data));

    }

    if (!ASN1_STRING_set(ret, buf, -1 /* use strlen */)) {

      return nullptr;

    }

  }

  if (out != nullptr && *out == nullptr) {

    *out = ret;

  }

  tmp.release();  // Ownership passed to caller.

  return ret;

}

int ASN1_TIME_set_string(ASN1_TIME *s, const char *str) {

  return ASN1_UTCTIME_set_string(s, str) ||

         ASN1_GENERALIZEDTIME_set_string(s, str);

}

int ASN1_TIME_set_string_X509(ASN1_TIME *s, const char *str) {

  CBS cbs;

  CBS_init(&cbs, (const uint8_t *)str, strlen(str));

  int type;

  struct tm tm;

  if (CBS_parse_utc_time(&cbs, /*out_tm=*/nullptr,

                         /*allow_timezone_offset=*/0)) {

    type = V_ASN1_UTCTIME;

  } else if (CBS_parse_generalized_time(&cbs, &tm,

                                        /*allow_timezone_offset=*/0)) {

    type = V_ASN1_GENERALIZEDTIME;

    if (fits_in_utc_time(&tm)) {

      type = V_ASN1_UTCTIME;

      CBS_skip(&cbs, 2);

    }

  } else {

    return 0;

  }

  if (s != nullptr) {

    if (!ASN1_STRING_set(s, CBS_data(&cbs), CBS_len(&cbs))) {

      return 0;

    }

    s->type = type;

  }

  return 1;

}

static int asn1_time_to_tm(struct tm *tm, const ASN1_TIME *t,

                           int allow_timezone_offset) {

  if (t == nullptr) {

    if (OPENSSL_posix_to_tm(time(nullptr), tm)) {

      return 1;

    }

    return 0;

  }

  if (t->type == V_ASN1_UTCTIME) {

    return asn1_utctime_to_tm(tm, t, allow_timezone_offset);

  } else if (t->type == V_ASN1_GENERALIZEDTIME) {

    return asn1_generalizedtime_to_tm(tm, t);

  }

  return 0;

}

int ASN1_TIME_diff(int *out_days, int *out_seconds, const ASN1_TIME *from,

                   const ASN1_TIME *to) {

  struct tm tm_from, tm_to;

  if (!asn1_time_to_tm(&tm_from, from, /*allow_timezone_offset=*/1)) {

    return 0;

  }

  if (!asn1_time_to_tm(&tm_to, to, /*allow_timezone_offset=*/1)) {

    return 0;

  }

  return OPENSSL_gmtime_diff(out_days, out_seconds, &tm_from, &tm_to);

}

int ASN1_TIME_to_posix_nonstandard(const ASN1_TIME *t, int64_t *out_time) {

  struct tm tm;

  if (!asn1_time_to_tm(&tm, t, /*allow_timezone_offset=*/1)) {

    return 0;

  }

  return OPENSSL_tm_to_posix(&tm, out_time);

}

// The functions below do *not* permissively allow the use of four digit

// timezone offsets in UTC times, as is done elsewhere in the code. They are

// both new API, and used internally to X509_cmp_time. This is to discourage the

// use of nonstandard times in new code, and to ensure that this code behaves

// correctly in X509_cmp_time which historically did its own time validations

// slightly different than the many other copies of X.509 time validation

// sprinkled through the codebase. The custom checks in X509_cmp_time meant that

// it did not allow four digit timezone offsets in UTC times.

int ASN1_TIME_to_time_t(const ASN1_TIME *t, time_t *out_time) {

  struct tm tm;

  if (!asn1_time_to_tm(&tm, t, /*allow_timezone_offset=*/0)) {

    return 0;

  }

  return OPENSSL_timegm(&tm, out_time);

}

int ASN1_TIME_to_posix(const ASN1_TIME *t, int64_t *out_time) {

  struct tm tm;

  if (!asn1_time_to_tm(&tm, t, /*allow_timezone_offset=*/0)) {

    return 0;

  }

  return OPENSSL_tm_to_posix(&tm, out_time);

}

int bssl::asn1_parse_time(CBS *cbs, ASN1_TIME *out,

                          int allow_utc_timezone_offset) {

  if (CBS_peek_asn1_tag(cbs, CBS_ASN1_UTCTIME)) {

    return asn1_parse_utc_time(cbs, out, /*tag=*/0, allow_utc_timezone_offset);

  }

  return asn1_parse_generalized_time(cbs, out, /*tag=*/0);

}

int bssl::asn1_marshal_time(CBB *cbb, const ASN1_TIME *in) {

  if (in->type != V_ASN1_UTCTIME && in->type != V_ASN1_GENERALIZEDTIME) {

    OPENSSL_PUT_ERROR(ASN1, ASN1_R_WRONG_TYPE);

    return 0;

  }

  return asn1_marshal_octet_string(cbb, in,

                                   static_cast<CBS_ASN1_TAG>(in->type));

}