// Copyright 2015 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #include "net/der/parser.h" #include "base/check.h" #include "net/der/parse_values.h" namespace net::der { Parser::Parser() { CBS_init(&cbs_, nullptr, 0); } Parser::Parser(const Input& input) { CBS_init(&cbs_, input.UnsafeData(), input.Length()); } bool Parser::PeekTagAndValue(Tag* tag, Input* out) { CBS peeker = cbs_; CBS tmp_out; size_t header_len; unsigned tag_value; if (!CBS_get_any_asn1_element(&peeker, &tmp_out, &tag_value, &header_len) || !CBS_skip(&tmp_out, header_len)) { return false; } advance_len_ = CBS_len(&tmp_out) + header_len; *tag = tag_value; *out = Input(CBS_data(&tmp_out), CBS_len(&tmp_out)); return true; } bool Parser::Advance() { if (advance_len_ == 0) return false; bool ret = !!CBS_skip(&cbs_, advance_len_); advance_len_ = 0; return ret; } bool Parser::HasMore() { return CBS_len(&cbs_) > 0; } bool Parser::ReadRawTLV(Input* out) { CBS tmp_out; if (!CBS_get_any_asn1_element(&cbs_, &tmp_out, nullptr, nullptr)) return false; *out = Input(CBS_data(&tmp_out), CBS_len(&tmp_out)); return true; } bool Parser::ReadTagAndValue(Tag* tag, Input* out) { if (!PeekTagAndValue(tag, out)) return false; CHECK(Advance()); return true; } bool Parser::ReadOptionalTag(Tag tag, absl::optional* out) { if (!HasMore()) { *out = absl::nullopt; return true; } Tag actual_tag; Input value; if (!PeekTagAndValue(&actual_tag, &value)) { return false; } if (actual_tag == tag) { CHECK(Advance()); *out = value; } else { advance_len_ = 0; *out = absl::nullopt; } return true; } bool Parser::ReadOptionalTag(Tag tag, Input* out, bool* present) { absl::optional tmp_out; if (!ReadOptionalTag(tag, &tmp_out)) return false; *present = tmp_out.has_value(); *out = tmp_out.value_or(der::Input()); return true; } bool Parser::SkipOptionalTag(Tag tag, bool* present) { Input out; return ReadOptionalTag(tag, &out, present); } bool Parser::ReadTag(Tag tag, Input* out) { Tag actual_tag; Input value; if (!PeekTagAndValue(&actual_tag, &value) || actual_tag != tag) { return false; } CHECK(Advance()); *out = value; return true; } bool Parser::SkipTag(Tag tag) { Input out; return ReadTag(tag, &out); } // Type-specific variants of ReadTag bool Parser::ReadConstructed(Tag tag, Parser* out) { if (!IsConstructed(tag)) return false; Input data; if (!ReadTag(tag, &data)) return false; *out = Parser(data); return true; } bool Parser::ReadSequence(Parser* out) { return ReadConstructed(kSequence, out); } bool Parser::ReadUint8(uint8_t* out) { Input encoded_int; if (!ReadTag(kInteger, &encoded_int)) return false; return ParseUint8(encoded_int, out); } bool Parser::ReadUint64(uint64_t* out) { Input encoded_int; if (!ReadTag(kInteger, &encoded_int)) return false; return ParseUint64(encoded_int, out); } absl::optional Parser::ReadBitString() { Input value; if (!ReadTag(kBitString, &value)) return absl::nullopt; return ParseBitString(value); } bool Parser::ReadGeneralizedTime(GeneralizedTime* out) { Input value; if (!ReadTag(kGeneralizedTime, &value)) return false; return ParseGeneralizedTime(value, out); } } // namespace net::der