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/*
* Copyright 2012 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
// This file contains declarations of interfaces that wrap SDP-related
// constructs; session descriptions and ICE candidates. The inner "cricket::"
// objects shouldn't be accessed directly; the intention is that an application
// using the PeerConnection API only creates these objects from strings, and
// them passes them into the PeerConnection.
//
// Though in the future, we're planning to provide an SDP parsing API, with a
// structure more friendly than cricket::SessionDescription.
#ifndef API_JSEP_H_
#define API_JSEP_H_
#include <stddef.h>
#include <memory>
#include <string>
#include <vector>
#include "absl/types/optional.h"
#include "api/ref_count.h"
#include "api/rtc_error.h"
#include "rtc_base/system/rtc_export.h"
namespace cricket {
class Candidate;
class SessionDescription;
} // namespace cricket
namespace webrtc {
struct SdpParseError {
public:
// The sdp line that causes the error.
std::string line;
// Explains the error.
std::string description;
};
// Class representation of an ICE candidate.
//
// An instance of this interface is supposed to be owned by one class at
// a time and is therefore not expected to be thread safe.
//
// An instance can be created by CreateIceCandidate.
class RTC_EXPORT IceCandidateInterface {
public:
virtual ~IceCandidateInterface() {}
// If present, this is the value of the "a=mid" attribute of the candidate's
// m= section in SDP, which identifies the m= section.
virtual std::string sdp_mid() const = 0;
// This indicates the index (starting at zero) of m= section this candidate
// is associated with. Needed when an endpoint doesn't support MIDs.
virtual int sdp_mline_index() const = 0;
// Only for use internally.
virtual const cricket::Candidate& candidate() const = 0;
// The URL of the ICE server which this candidate was gathered from.
// TODO(zhihuang): Remove the default implementation once the subclasses
// implement this method.
virtual std::string server_url() const;
// Creates a SDP-ized form of this candidate.
virtual bool ToString(std::string* out) const = 0;
};
// Creates a IceCandidateInterface based on SDP string.
// Returns null if the sdp string can't be parsed.
// `error` may be null.
RTC_EXPORT IceCandidateInterface* CreateIceCandidate(const std::string& sdp_mid,
int sdp_mline_index,
const std::string& sdp,
SdpParseError* error);
// Creates an IceCandidateInterface based on a parsed candidate structure.
RTC_EXPORT std::unique_ptr<IceCandidateInterface> CreateIceCandidate(
const std::string& sdp_mid,
int sdp_mline_index,
const cricket::Candidate& candidate);
// This class represents a collection of candidates for a specific m= section.
// Used in SessionDescriptionInterface.
class IceCandidateCollection {
public:
virtual ~IceCandidateCollection() {}
virtual size_t count() const = 0;
// Returns true if an equivalent `candidate` exist in the collection.
virtual bool HasCandidate(const IceCandidateInterface* candidate) const = 0;
virtual const IceCandidateInterface* at(size_t index) const = 0;
};
// Enum that describes the type of the SessionDescriptionInterface.
// Corresponds to RTCSdpType in the WebRTC specification.
enum class SdpType {
kOffer, // Description must be treated as an SDP offer.
kPrAnswer, // Description must be treated as an SDP answer, but not a final
// answer.
kAnswer, // Description must be treated as an SDP final answer, and the
// offer-answer exchange must be considered complete after
// receiving this.
kRollback // Resets any pending offers and sets signaling state back to
// stable.
};
// Returns the string form of the given SDP type. String forms are defined in
// SessionDescriptionInterface.
RTC_EXPORT const char* SdpTypeToString(SdpType type);
// Returns the SdpType from its string form. The string form can be one of the
// constants defined in SessionDescriptionInterface. Passing in any other string
// results in nullopt.
RTC_EXPORT absl::optional<SdpType> SdpTypeFromString(
const std::string& type_str);
// Class representation of an SDP session description.
//
// An instance of this interface is supposed to be owned by one class at a time
// and is therefore not expected to be thread safe.
//
// An instance can be created by CreateSessionDescription.
class RTC_EXPORT SessionDescriptionInterface {
public:
// String representations of the supported SDP types.
static const char kOffer[];
static const char kPrAnswer[];
static const char kAnswer[];
static const char kRollback[];
virtual ~SessionDescriptionInterface() {}
// Create a new SessionDescriptionInterface object
// with the same values as the old object.
// TODO(bugs.webrtc.org:12215): Remove default implementation
virtual std::unique_ptr<SessionDescriptionInterface> Clone() const {
return nullptr;
}
// Only for use internally.
virtual cricket::SessionDescription* description() = 0;
virtual const cricket::SessionDescription* description() const = 0;
// Get the session id and session version, which are defined based on
// RFC 4566 for the SDP o= line.
virtual std::string session_id() const = 0;
virtual std::string session_version() const = 0;
// Returns the type of this session description as an SdpType. Descriptions of
// the various types are found in the SdpType documentation.
// TODO(steveanton): Remove default implementation once Chromium has been
// updated.
virtual SdpType GetType() const;
// kOffer/kPrAnswer/kAnswer
// TODO(steveanton): Remove this in favor of `GetType` that returns SdpType.
virtual std::string type() const = 0;
// Adds the specified candidate to the description.
//
// Ownership is not transferred.
//
// Returns false if the session description does not have a media section
// that corresponds to `candidate.sdp_mid()` or
// `candidate.sdp_mline_index()`.
virtual bool AddCandidate(const IceCandidateInterface* candidate) = 0;
// Removes the candidates from the description, if found.
//
// Returns the number of candidates removed.
virtual size_t RemoveCandidates(
const std::vector<cricket::Candidate>& candidates);
// Returns the number of m= sections in the session description.
virtual size_t number_of_mediasections() const = 0;
// Returns a collection of all candidates that belong to a certain m=
// section.
virtual const IceCandidateCollection* candidates(
size_t mediasection_index) const = 0;
// Serializes the description to SDP.
virtual bool ToString(std::string* out) const = 0;
};
// Creates a SessionDescriptionInterface based on the SDP string and the type.
// Returns null if the sdp string can't be parsed or the type is unsupported.
// `error` may be null.
// TODO(steveanton): This function is deprecated. Please use the functions below
// which take an SdpType enum instead. Remove this once it is no longer used.
RTC_EXPORT SessionDescriptionInterface* CreateSessionDescription(
const std::string& type,
const std::string& sdp,
SdpParseError* error);
// Creates a SessionDescriptionInterface based on the SDP string and the type.
// Returns null if the SDP string cannot be parsed.
// If using the signature with `error_out`, details of the parsing error may be
// written to `error_out` if it is not null.
RTC_EXPORT std::unique_ptr<SessionDescriptionInterface>
CreateSessionDescription(SdpType type, const std::string& sdp);
RTC_EXPORT std::unique_ptr<SessionDescriptionInterface>
CreateSessionDescription(SdpType type,
const std::string& sdp,
SdpParseError* error_out);
// Creates a SessionDescriptionInterface based on a parsed SDP structure and the
// given type, ID and version.
std::unique_ptr<SessionDescriptionInterface> CreateSessionDescription(
SdpType type,
const std::string& session_id,
const std::string& session_version,
std::unique_ptr<cricket::SessionDescription> description);
// CreateOffer and CreateAnswer callback interface.
class RTC_EXPORT CreateSessionDescriptionObserver
: public webrtc::RefCountInterface {
public:
// This callback transfers the ownership of the `desc`.
// TODO(deadbeef): Make this take an std::unique_ptr<> to avoid confusion
// around ownership.
virtual void OnSuccess(SessionDescriptionInterface* desc) = 0;
// The OnFailure callback takes an RTCError, which consists of an
// error code and a string.
// RTCError is non-copyable, so it must be passed using std::move.
// Earlier versions of the API used a string argument. This version
// is removed; its functionality was the same as passing
// error.message.
virtual void OnFailure(RTCError error) = 0;
protected:
~CreateSessionDescriptionObserver() override = default;
};
// SetLocalDescription and SetRemoteDescription callback interface.
class RTC_EXPORT SetSessionDescriptionObserver
: public webrtc::RefCountInterface {
public:
virtual void OnSuccess() = 0;
// See description in CreateSessionDescriptionObserver for OnFailure.
virtual void OnFailure(RTCError error) = 0;
protected:
~SetSessionDescriptionObserver() override = default;
};
} // namespace webrtc
#endif // API_JSEP_H_