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- // Copyright (c) 2010 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/cert/pem.h"
- #include "base/base64.h"
- #include "base/strings/string_piece.h"
- #include "base/strings/string_util.h"
- #include "base/strings/stringprintf.h"
- namespace {
- const char kPEMSearchBlock[] = "-----BEGIN ";
- const char kPEMBeginBlock[] = "-----BEGIN %s-----";
- const char kPEMEndBlock[] = "-----END %s-----";
- } // namespace
- namespace net {
- using base::StringPiece;
- struct PEMTokenizer::PEMType {
- std::string type;
- std::string header;
- std::string footer;
- };
- PEMTokenizer::PEMTokenizer(
- const StringPiece& str,
- const std::vector<std::string>& allowed_block_types) {
- Init(str, allowed_block_types);
- }
- PEMTokenizer::~PEMTokenizer() = default;
- bool PEMTokenizer::GetNext() {
- while (pos_ != StringPiece::npos) {
- // Scan for the beginning of the next PEM encoded block.
- pos_ = str_.find(kPEMSearchBlock, pos_);
- if (pos_ == StringPiece::npos)
- return false; // No more PEM blocks
- std::vector<PEMType>::const_iterator it;
- // Check to see if it is of an acceptable block type.
- for (it = block_types_.begin(); it != block_types_.end(); ++it) {
- if (!base::StartsWith(str_.substr(pos_), it->header))
- continue;
- // Look for a footer matching the header. If none is found, then all
- // data following this point is invalid and should not be parsed.
- StringPiece::size_type footer_pos = str_.find(it->footer, pos_);
- if (footer_pos == StringPiece::npos) {
- pos_ = StringPiece::npos;
- return false;
- }
- // Chop off the header and footer and parse the data in between.
- StringPiece::size_type data_begin = pos_ + it->header.size();
- pos_ = footer_pos + it->footer.size();
- block_type_ = it->type;
- StringPiece encoded = str_.substr(data_begin, footer_pos - data_begin);
- if (!base::Base64Decode(base::CollapseWhitespaceASCII(encoded, true),
- &data_)) {
- // The most likely cause for a decode failure is a datatype that
- // includes PEM headers, which are not supported.
- break;
- }
- return true;
- }
- // If the block did not match any acceptable type, move past it and
- // continue the search. Otherwise, |pos_| has been updated to the most
- // appropriate search position to continue searching from and should not
- // be adjusted.
- if (it == block_types_.end())
- pos_ += sizeof(kPEMSearchBlock);
- }
- return false;
- }
- void PEMTokenizer::Init(const StringPiece& str,
- const std::vector<std::string>& allowed_block_types) {
- str_ = str;
- pos_ = 0;
- // Construct PEM header/footer strings for all the accepted types, to
- // reduce parsing later.
- for (const auto& allowed_block_type : allowed_block_types) {
- PEMType allowed_type;
- allowed_type.type = allowed_block_type;
- allowed_type.header =
- base::StringPrintf(kPEMBeginBlock, allowed_block_type.c_str());
- allowed_type.footer =
- base::StringPrintf(kPEMEndBlock, allowed_block_type.c_str());
- block_types_.push_back(allowed_type);
- }
- }
- std::string PEMEncode(base::StringPiece data, const std::string& type) {
- std::string b64_encoded;
- base::Base64Encode(data, &b64_encoded);
- // Divide the Base-64 encoded data into 64-character chunks, as per
- // 4.3.2.4 of RFC 1421.
- static const size_t kChunkSize = 64;
- size_t chunks = (b64_encoded.size() + (kChunkSize - 1)) / kChunkSize;
- std::string pem_encoded;
- pem_encoded.reserve(
- // header & footer
- 17 + 15 + type.size() * 2 +
- // encoded data
- b64_encoded.size() +
- // newline characters for line wrapping in encoded data
- chunks);
- pem_encoded = "-----BEGIN ";
- pem_encoded.append(type);
- pem_encoded.append("-----\n");
- for (size_t i = 0, chunk_offset = 0; i < chunks;
- ++i, chunk_offset += kChunkSize) {
- pem_encoded.append(b64_encoded, chunk_offset, kChunkSize);
- pem_encoded.append("\n");
- }
- pem_encoded.append("-----END ");
- pem_encoded.append(type);
- pem_encoded.append("-----\n");
- return pem_encoded;
- }
- } // namespace net
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