1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/security/pkix/lib/pkixder.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,82 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim: set ts=8 sts=2 et sw=2 tw=80: */
1.6 +/* Copyright 2013 Mozilla Foundation
1.7 + *
1.8 + * Licensed under the Apache License, Version 2.0 (the "License");
1.9 + * you may not use this file except in compliance with the License.
1.10 + * You may obtain a copy of the License at
1.11 + *
1.12 + * http://www.apache.org/licenses/LICENSE-2.0
1.13 + *
1.14 + * Unless required by applicable law or agreed to in writing, software
1.15 + * distributed under the License is distributed on an "AS IS" BASIS,
1.16 + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
1.17 + * See the License for the specific language governing permissions and
1.18 + * limitations under the License.
1.19 + */
1.20 +
1.21 +#include "pkixder.h"
1.22 +
1.23 +namespace mozilla { namespace pkix { namespace der {
1.24 +
1.25 +// not inline
1.26 +Result
1.27 +Fail(PRErrorCode errorCode)
1.28 +{
1.29 + PR_SetError(errorCode, 0);
1.30 + return Failure;
1.31 +}
1.32 +
1.33 +// Too complicated to be inline
1.34 +Result
1.35 +ExpectTagAndGetLength(Input& input, uint8_t expectedTag, uint16_t& length)
1.36 +{
1.37 + PR_ASSERT((expectedTag & 0x1F) != 0x1F); // high tag number form not allowed
1.38 +
1.39 + uint8_t tag;
1.40 + if (input.Read(tag) != Success) {
1.41 + return Failure;
1.42 + }
1.43 +
1.44 + if (tag != expectedTag) {
1.45 + return Fail(SEC_ERROR_BAD_DER);
1.46 + }
1.47 +
1.48 + // The short form of length is a single byte with the high order bit set
1.49 + // to zero. The long form of length is one byte with the high order bit
1.50 + // set, followed by N bytes, where N is encoded in the lowest 7 bits of
1.51 + // the first byte.
1.52 + uint8_t length1;
1.53 + if (input.Read(length1) != Success) {
1.54 + return Failure;
1.55 + }
1.56 + if (!(length1 & 0x80)) {
1.57 + length = length1;
1.58 + } else if (length1 == 0x81) {
1.59 + uint8_t length2;
1.60 + if (input.Read(length2) != Success) {
1.61 + return Failure;
1.62 + }
1.63 + if (length2 < 128) {
1.64 + // Not shortest possible encoding
1.65 + return Fail(SEC_ERROR_BAD_DER);
1.66 + }
1.67 + length = length2;
1.68 + } else if (length1 == 0x82) {
1.69 + if (input.Read(length) != Success) {
1.70 + return Failure;
1.71 + }
1.72 + if (length < 256) {
1.73 + // Not shortest possible encoding
1.74 + return Fail(SEC_ERROR_BAD_DER);
1.75 + }
1.76 + } else {
1.77 + // We don't support lengths larger than 2^16 - 1.
1.78 + return Fail(SEC_ERROR_BAD_DER);
1.79 + }
1.80 +
1.81 + // Ensure the input is long enough for the length it says it has.
1.82 + return input.EnsureLength(length);
1.83 +}
1.84 +
1.85 +} } } // namespace mozilla::pkix::der
