| // Copyright 2016 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 "remoting/protocol/sdp_message.h" |
| |
| #include <algorithm> |
| |
| #include "base/logging.h" |
| #include "base/strings/string_piece.h" |
| #include "base/strings/string_split.h" |
| #include "base/strings/string_util.h" |
| |
| namespace remoting { |
| namespace protocol { |
| |
| SdpMessage::SdpMessage(const std::string& sdp) { |
| sdp_lines_ = base::SplitString( |
| sdp, "\n", base::TRIM_WHITESPACE, base::SPLIT_WANT_NONEMPTY); |
| for (const auto& line : sdp_lines_) { |
| if (base::StartsWith(line, "m=audio", base::CompareCase::SENSITIVE)) |
| has_audio_ = true; |
| if (base::StartsWith(line, "m=video", base::CompareCase::SENSITIVE)) |
| has_video_ = true; |
| } |
| } |
| |
| SdpMessage::~SdpMessage() {} |
| |
| std::string SdpMessage::ToString() const { |
| return base::JoinString(sdp_lines_, "\n") + "\n"; |
| } |
| |
| bool SdpMessage::AddCodecParameter(const std::string& codec, |
| const std::string& parameters_to_add) { |
| int line_num; |
| std::string payload_type; |
| bool codec_found = FindCodec(codec, &line_num, &payload_type); |
| if (!codec_found) { |
| return false; |
| } |
| sdp_lines_.insert(sdp_lines_.begin() + line_num + 1, |
| "a=fmtp:" + payload_type + ' ' + parameters_to_add); |
| return true; |
| } |
| |
| bool SdpMessage::PreferVideoCodec(const std::string& codec) { |
| if (!has_video_) { |
| return false; |
| } |
| std::string payload_type; |
| if (!FindCodec(codec, nullptr, &payload_type)) { |
| return false; |
| } |
| |
| for (size_t i = 0; i < sdp_lines_.size(); i++) { |
| if (!base::StartsWith(sdp_lines_[i], |
| "m=video", |
| base::CompareCase::SENSITIVE)) { |
| continue; |
| } |
| |
| // A valid SDP contains only one "m=video" line. So instead of continue, if |
| // this line is invalid, we should return false immediately. |
| std::vector<base::StringPiece> fields = base::SplitStringPiece( |
| sdp_lines_[i], " ", base::TRIM_WHITESPACE, base::SPLIT_WANT_NONEMPTY); |
| // The first three fields are "m=video", port and proto. |
| static constexpr int kSkipFields = 3; |
| if (fields.size() <= kSkipFields) { |
| return false; |
| } |
| |
| const auto first_codec_pos = fields.begin() + kSkipFields; |
| auto pos = std::find(first_codec_pos, |
| fields.end(), |
| base::StringPiece(payload_type)); |
| // The codec has not been found in codec list. |
| if (pos == fields.end()) { |
| return false; |
| } |
| |
| std::rotate(first_codec_pos, pos, pos + 1); |
| sdp_lines_[i] = base::JoinString(fields, " "); |
| return true; |
| } |
| |
| // If has_video_ is true (tested at the very beginning of the function), we |
| // should always return within the for-loop above. |
| NOTREACHED(); |
| return false; |
| } |
| |
| bool SdpMessage::FindCodec(const std::string& codec, |
| int* line_num, |
| std::string* payload_type) const { |
| const std::string kRtpMapPrefix = "a=rtpmap:"; |
| for (size_t i = 0; i < sdp_lines_.size(); ++i) { |
| const auto& line = sdp_lines_[i]; |
| if (!base::StartsWith(line, kRtpMapPrefix, base::CompareCase::SENSITIVE)) |
| continue; |
| size_t space_pos = line.find(' '); |
| if (space_pos == std::string::npos) |
| continue; |
| if (line.substr(space_pos + 1, codec.size()) == codec && |
| line[space_pos + 1 + codec.size()] == '/') { |
| if (line_num) { |
| *line_num = i; |
| } |
| if (payload_type) { |
| *payload_type = |
| line.substr(kRtpMapPrefix.size(), space_pos - kRtpMapPrefix.size()); |
| } |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| } // namespace protocol |
| } // namespace remoting |