blob_encoding.cc (2981B)
1 /* 2 * Copyright (c) 2018 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #include "logging/rtc_event_log/encoder/blob_encoding.h" 12 13 #include <cstddef> 14 #include <cstdint> 15 #include <string> 16 #include <tuple> 17 #include <vector> 18 19 #include "absl/strings/string_view.h" 20 #include "logging/rtc_event_log/encoder/var_int.h" 21 #include "rtc_base/checks.h" 22 #include "rtc_base/logging.h" 23 24 namespace webrtc { 25 26 std::string EncodeBlobs(const std::vector<std::string>& blobs) { 27 RTC_DCHECK(!blobs.empty()); 28 29 size_t result_length_bound = kMaxVarIntLengthBytes * blobs.size(); 30 for (const auto& blob : blobs) { 31 // Providing an input so long that it would cause a wrap-around is an error. 32 RTC_DCHECK_GE(result_length_bound + blob.length(), result_length_bound); 33 result_length_bound += blob.length(); 34 } 35 36 std::string result; 37 result.reserve(result_length_bound); 38 39 // First, encode all of the lengths. 40 for (absl::string_view blob : blobs) { 41 result += EncodeVarInt(blob.length()); 42 } 43 44 // Second, encode the actual blobs. 45 for (absl::string_view blob : blobs) { 46 result.append(blob.data(), blob.length()); 47 } 48 49 RTC_DCHECK_LE(result.size(), result_length_bound); 50 return result; 51 } 52 53 std::vector<absl::string_view> DecodeBlobs(absl::string_view encoded_blobs, 54 size_t num_of_blobs) { 55 if (encoded_blobs.empty()) { 56 RTC_LOG(LS_WARNING) << "Corrupt input; empty input."; 57 return std::vector<absl::string_view>(); 58 } 59 60 if (num_of_blobs == 0u) { 61 RTC_LOG(LS_WARNING) 62 << "Corrupt input; number of blobs must be greater than 0."; 63 return std::vector<absl::string_view>(); 64 } 65 66 // Read the lengths of all blobs. 67 std::vector<uint64_t> lengths(num_of_blobs); 68 for (size_t i = 0; i < num_of_blobs; ++i) { 69 bool success = false; 70 std::tie(success, encoded_blobs) = DecodeVarInt(encoded_blobs, &lengths[i]); 71 if (!success) { 72 RTC_LOG(LS_WARNING) << "Corrupt input; varint decoding failed."; 73 return std::vector<absl::string_view>(); 74 } 75 } 76 77 // Read the blobs themselves. 78 std::vector<absl::string_view> blobs(num_of_blobs); 79 for (size_t i = 0; i < num_of_blobs; ++i) { 80 if (lengths[i] > encoded_blobs.length()) { 81 RTC_LOG(LS_WARNING) << "Corrupt input; blob sizes exceed input size."; 82 return std::vector<absl::string_view>(); 83 } 84 85 blobs[i] = encoded_blobs.substr(0, lengths[i]); 86 encoded_blobs = encoded_blobs.substr(lengths[i]); 87 } 88 89 if (!encoded_blobs.empty()) { 90 RTC_LOG(LS_WARNING) << "Corrupt input; unrecognized trailer."; 91 return std::vector<absl::string_view>(); 92 } 93 94 return blobs; 95 } 96 97 } // namespace webrtc