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author | Tianjie Xu <xunchang@google.com> | 2019-03-29 23:04:04 +0100 |
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committer | android-build-merger <android-build-merger@google.com> | 2019-03-29 23:04:04 +0100 |
commit | 8e39f3d54e0cb403be80c248286be14a5a427814 (patch) | |
tree | b31bd3f84794bbbea30d04e2e7465d0957fee209 /install/asn1_decoder.cpp | |
parent | Merge "Use flags = 0 to avoid fd closing for child updater process" am: 50bda24f1e am: 111663d893 (diff) | |
parent | Merge "Move install to separate module" am: a232d9dccb (diff) | |
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Diffstat (limited to 'install/asn1_decoder.cpp')
-rw-r--r-- | install/asn1_decoder.cpp | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/install/asn1_decoder.cpp b/install/asn1_decoder.cpp new file mode 100644 index 000000000..2d81a6e13 --- /dev/null +++ b/install/asn1_decoder.cpp @@ -0,0 +1,156 @@ +/* + * Copyright (C) 2013 The Android Open Source Project + * + * 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 + * + * http://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 "private/asn1_decoder.h" + +int asn1_context::peek_byte() const { + if (length_ == 0) { + return -1; + } + return *p_; +} + +int asn1_context::get_byte() { + if (length_ == 0) { + return -1; + } + + int byte = *p_; + p_++; + length_--; + return byte; +} + +bool asn1_context::skip_bytes(size_t num_skip) { + if (length_ < num_skip) { + return false; + } + p_ += num_skip; + length_ -= num_skip; + return true; +} + +bool asn1_context::decode_length(size_t* out_len) { + int num_octets = get_byte(); + if (num_octets == -1) { + return false; + } + if ((num_octets & 0x80) == 0x00) { + *out_len = num_octets; + return true; + } + num_octets &= kMaskTag; + if (static_cast<size_t>(num_octets) >= sizeof(size_t)) { + return false; + } + size_t length = 0; + for (int i = 0; i < num_octets; ++i) { + int byte = get_byte(); + if (byte == -1) { + return false; + } + length <<= 8; + length += byte; + } + *out_len = length; + return true; +} + +/** + * Returns the constructed type and advances the pointer. E.g. A0 -> 0 + */ +asn1_context* asn1_context::asn1_constructed_get() { + int type = get_byte(); + if (type == -1 || (type & kMaskConstructed) != kTagConstructed) { + return nullptr; + } + size_t length; + if (!decode_length(&length) || length > length_) { + return nullptr; + } + asn1_context* app_ctx = new asn1_context(p_, length); + app_ctx->app_type_ = type & kMaskAppType; + return app_ctx; +} + +bool asn1_context::asn1_constructed_skip_all() { + int byte = peek_byte(); + while (byte != -1 && (byte & kMaskConstructed) == kTagConstructed) { + skip_bytes(1); + size_t length; + if (!decode_length(&length) || !skip_bytes(length)) { + return false; + } + byte = peek_byte(); + } + return byte != -1; +} + +int asn1_context::asn1_constructed_type() const { + return app_type_; +} + +asn1_context* asn1_context::asn1_sequence_get() { + if ((get_byte() & kMaskTag) != kTagSequence) { + return nullptr; + } + size_t length; + if (!decode_length(&length) || length > length_) { + return nullptr; + } + return new asn1_context(p_, length); +} + +asn1_context* asn1_context::asn1_set_get() { + if ((get_byte() & kMaskTag) != kTagSet) { + return nullptr; + } + size_t length; + if (!decode_length(&length) || length > length_) { + return nullptr; + } + return new asn1_context(p_, length); +} + +bool asn1_context::asn1_sequence_next() { + size_t length; + if (get_byte() == -1 || !decode_length(&length) || !skip_bytes(length)) { + return false; + } + return true; +} + +bool asn1_context::asn1_oid_get(const uint8_t** oid, size_t* length) { + if (get_byte() != kTagOid) { + return false; + } + if (!decode_length(length) || *length == 0 || *length > length_) { + return false; + } + *oid = p_; + return true; +} + +bool asn1_context::asn1_octet_string_get(const uint8_t** octet_string, size_t* length) { + if (get_byte() != kTagOctetString) { + return false; + } + if (!decode_length(length) || *length == 0 || *length > length_) { + return false; + } + *octet_string = p_; + return true; +} |