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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef REMOTING_PROTOCOL_SDP_MESSAGE_H_
#define REMOTING_PROTOCOL_SDP_MESSAGE_H_
#include <map>
#include <string>
#include <vector>
namespace webrtc {
struct SdpVideoFormat;
}
namespace remoting::protocol {
// SdpMessage is used to process session descriptions messages in SDP format
// generated by WebRTC (see RFC 4566). In particularly it allows configuring
// video and audio codecs.
//
// It also normalizes the SDP message to make sure the text used for HMAC
// signature verification is the same that was signed on the sending side.
// This is necessary because WebRTC generates SDP with CRLF line endings which
// are sometimes converted to LF after passing the signaling channel.
class SdpMessage {
public:
explicit SdpMessage(const std::string& sdp);
~SdpMessage();
bool has_audio() const { return has_audio_; }
bool has_video() const { return has_video_; }
// Returns string representation of the SDP message. The result always has
// line-endings normalized to CR+LF and empty lines removed.
std::string ToString() const;
// Returns string representation of the SDP message for the purpose of
// computing or verifying its signature, which is transmitted along with the
// SDP over signaling channel. This must be implemented in exactly the same
// way at each end of the connection.
std::string NormalizedForSignature() const;
// Adds specified parameters for the |codec|. Returns false if the |codec| is
// not listed anywhere in the SDP message.
bool AddCodecParameter(const std::string& codec,
const std::string& parameters_to_add);
// Reorders the list of video formats by placing the payload associated with
// |format| at the front. By doing this, the sender-side of the connection
// will try to use that codec first. The SDP message will not be modified if
// |format| is not a supported codec.
void SetPreferredVideoFormat(const webrtc::SdpVideoFormat& format);
private:
struct Payload {
size_t index;
std::string type;
};
using Payloads = std::vector<Payload>;
// Finds the lines of the form "a=rtpmap:<payload_type> <codec>/.." with the
// specified |codec| and returns a list of the matching payload types with
// their line numbers.
Payloads FindCodecPayloads(const std::string& codec) const;
// Overload for |FindCodec| which also filters based on fmtp parameter, such
// as profile-id for video codecs.
Payloads FindCodecPayloads(const std::string& codec,
const std::string& fmtp_param) const;
std::string GetFmtpFragmentForSdpVideoFormat(
const webrtc::SdpVideoFormat& format) const;
std::vector<std::string> sdp_lines_;
bool has_audio_ = false;
bool has_video_ = false;
};
} // namespace remoting::protocol
#endif // REMOTING_PROTOCOL_SDP_MESSAGE_H_
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