The Tor Browser: security/pkix/lib/pkixder.cpp@141e0f1194b1

     1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

     2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */

     3 /* Copyright 2013 Mozilla Foundation

     4  *

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

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

     7  * You may obtain a copy of the License at

     8  *

     9  *     http://www.apache.org/licenses/LICENSE-2.0

    10  *

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

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

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

    14  * See the License for the specific language governing permissions and

    15  * limitations under the License.

    16  */

    18 #include "pkixder.h"

    20 namespace mozilla { namespace pkix { namespace der {

    22 // not inline

    23 Result

    24 Fail(PRErrorCode errorCode)

    25 {

    26   PR_SetError(errorCode, 0);

    27   return Failure;

    28 }

    30 // Too complicated to be inline

    31 Result

    32 ExpectTagAndGetLength(Input& input, uint8_t expectedTag, uint16_t& length)

    33 {

    34   PR_ASSERT((expectedTag & 0x1F) != 0x1F); // high tag number form not allowed

    36   uint8_t tag;

    37   if (input.Read(tag) != Success) {

    38     return Failure;

    39   }

    41   if (tag != expectedTag) {

    42     return Fail(SEC_ERROR_BAD_DER);

    43   }

    45   // The short form of length is a single byte with the high order bit set

    46   // to zero. The long form of length is one byte with the high order bit

    47   // set, followed by N bytes, where N is encoded in the lowest 7 bits of

    48   // the first byte.

    49   uint8_t length1;

    50   if (input.Read(length1) != Success) {

    51     return Failure;

    52   }

    53   if (!(length1 & 0x80)) {

    54     length = length1;

    55   } else if (length1 == 0x81) {

    56     uint8_t length2;

    57     if (input.Read(length2) != Success) {

    58       return Failure;

    59     }

    60     if (length2 < 128) {

    61       // Not shortest possible encoding

    62       return Fail(SEC_ERROR_BAD_DER);

    63     }

    64     length = length2;

    65   } else if (length1 == 0x82) {

    66     if (input.Read(length) != Success) {

    67       return Failure;

    68     }

    69     if (length < 256) {

    70       // Not shortest possible encoding

    71       return Fail(SEC_ERROR_BAD_DER);

    72     }

    73   } else {

    74     // We don't support lengths larger than 2^16 - 1.

    75     return Fail(SEC_ERROR_BAD_DER);

    76   }

    78   // Ensure the input is long enough for the length it says it has.

    79   return input.EnsureLength(length);

    80 }

    82 } } } // namespace mozilla::pkix::der

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