// 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 #include #include "base/notreached.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() = default; std::string SdpMessage::ToString() const { return base::JoinString(sdp_lines_, "\r\n") + "\r\n"; } std::string SdpMessage::NormalizedForSignature() const { return base::JoinString(sdp_lines_, "\n") + "\n"; } bool SdpMessage::AddCodecParameter(const std::string& codec, const std::string& parameters_to_add) { std::vector> payload_types = FindCodec(codec); if (payload_types.empty()) { return false; } for (size_t i = 0; i < payload_types.size(); i++) { sdp_lines_.insert( sdp_lines_.begin() + payload_types[i].first + i + 1, "a=fmtp:" + payload_types[i].second + ' ' + parameters_to_add); } return true; } bool SdpMessage::PreferVideoCodec(const std::string& codec) { if (!has_video_) { return false; } std::vector> payload_types = FindCodec(codec); if (payload_types.empty()) { 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 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; for (const auto& payload : payload_types) { auto pos = std::find(first_codec_pos, fields.end(), base::StringPiece(payload.second)); // The codec has not been found in codec list. if (pos == fields.end()) { continue; } 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; } std::vector> SdpMessage::FindCodec( const std::string& codec) const { const std::string kRtpMapPrefix = "a=rtpmap:"; std::vector> results; 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()] == '/') { std::string payload_type = line.substr(kRtpMapPrefix.size(), space_pos - kRtpMapPrefix.size()); results.push_back(std::make_pair(i, std::move(payload_type))); } } return results; } } // namespace protocol } // namespace remoting