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- // 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 <utility>
- #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<std::pair<int, std::string>> 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<std::pair<int, std::string>> 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<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;
- 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<std::pair<int, std::string>> SdpMessage::FindCodec(
- const std::string& codec) const {
- const std::string kRtpMapPrefix = "a=rtpmap:";
- std::vector<std::pair<int, std::string>> 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
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