Add sdputils.h with useful functions for working with session descriptions

Bug: webrtc:8222
Change-Id: Iedeb65dad493721c5a4eddab254097171dfdb522
Reviewed-on: https://webrtc-review.googlesource.com/7120
Commit-Queue: Steve Anton <steveanton@webrtc.org>
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20192}

pc/BUILD.gn

@@ -139,6 +139,8 @@ rtc_static_library("peerconnection") {
     "rtpsender.h",
     "sctputils.cc",
     "sctputils.h",
+    "sdputils.cc",
+    "sdputils.h",
     "statscollector.cc",
     "statscollector.h",
     "streamcollection.h",

pc/peerconnectionwrapper.cc

@@ -16,6 +16,7 @@
 
 #include "api/jsepsessiondescription.h"
 #include "media/base/fakevideocapturer.h"
+#include "pc/sdputils.h"
 #include "rtc_base/gunit.h"
 #include "rtc_base/ptr_util.h"
 
@@ -129,16 +130,6 @@ bool PeerConnectionWrapper::SetSdp(
   return observer->result();
 }
 
-std::unique_ptr<SessionDescriptionInterface>
-PeerConnectionWrapper::CloneSessionDescription(
-    const SessionDescriptionInterface* desc) {
-  std::unique_ptr<JsepSessionDescription> clone(
-      new JsepSessionDescription(desc->type()));
-  RTC_DCHECK(clone->Initialize(desc->description()->Copy(), desc->session_id(),
-                               desc->session_version()));
-  return clone;
-}
-
 void PeerConnectionWrapper::AddAudioStream(const std::string& stream_label,
                                            const std::string& track_label) {
   auto stream = pc_factory()->CreateLocalMediaStream(stream_label);

pc/peerconnectionwrapper.h

@@ -95,8 +95,6 @@ class PeerConnectionWrapper {
   std::unique_ptr<SessionDescriptionInterface> CreateSdp(
       std::function<void(CreateSessionDescriptionObserver*)> fn);
   bool SetSdp(std::function<void(SetSessionDescriptionObserver*)> fn);
-  std::unique_ptr<SessionDescriptionInterface> CloneSessionDescription(
-      const SessionDescriptionInterface* desc);
 
   rtc::scoped_refptr<PeerConnectionFactoryInterface> pc_factory_;
   rtc::scoped_refptr<PeerConnectionInterface> pc_;

pc/sdputils.cc

@@ -0,0 +1,58 @@
+/*
+ *  Copyright 2017 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.
+ */
+
+#include "pc/sdputils.h"
+
+#include <utility>
+
+#include "api/jsepsessiondescription.h"
+#include "rtc_base/ptr_util.h"
+
+namespace webrtc {
+
+std::unique_ptr<SessionDescriptionInterface> CloneSessionDescription(
+    const SessionDescriptionInterface* sdesc) {
+  RTC_DCHECK(sdesc);
+  auto clone = rtc::MakeUnique<JsepSessionDescription>(sdesc->type());
+  clone->Initialize(sdesc->description()->Copy(), sdesc->session_id(),
+                              sdesc->session_version());
+  // As of writing, our version of GCC does not allow returning a unique_ptr of
+  // a subclass as a unique_ptr of a base class. To get around this, we need to
+  // std::move the return value.
+  return std::move(clone);
+}
+
+bool SdpContentsAll(SdpContentPredicate pred,
+                    const cricket::SessionDescription* desc) {
+  RTC_DCHECK(desc);
+  for (const auto& content : desc->contents()) {
+    const auto* transport_info = desc->GetTransportInfoByName(content.name);
+    if (!pred(&content, transport_info)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool SdpContentsNone(SdpContentPredicate pred,
+                     const cricket::SessionDescription* desc) {
+  return SdpContentsAll(std::not2(pred), desc);
+}
+
+void SdpContentsForEach(SdpContentMutator fn,
+                        cricket::SessionDescription* desc) {
+  RTC_DCHECK(desc);
+  for (auto& content : desc->contents()) {
+    auto* transport_info = desc->GetTransportInfoByName(content.name);
+    fn(&content, transport_info);
+  }
+}
+
+}  // namespace webrtc

pc/sdputils.h

@@ -0,0 +1,54 @@
+/*
+ *  Copyright 2017 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.
+ */
+
+#ifndef PC_SDPUTILS_H_
+#define PC_SDPUTILS_H_
+
+#include <functional>
+#include <memory>
+
+#include "api/jsep.h"
+#include "p2p/base/sessiondescription.h"
+
+namespace webrtc {
+
+// Returns a copy of the given session description.
+std::unique_ptr<SessionDescriptionInterface> CloneSessionDescription(
+    const SessionDescriptionInterface* sdesc);
+
+// Function that takes a single session description content with its
+// corresponding transport and produces a boolean.
+typedef std::function<bool(const cricket::ContentInfo*,
+                           const cricket::TransportInfo*)>
+    SdpContentPredicate;
+
+// Returns true if the predicate returns true for all contents in the given
+// session description.
+bool SdpContentsAll(SdpContentPredicate pred,
+                    const cricket::SessionDescription* desc);
+
+// Returns true if the predicate returns true for none of the contents in the
+// given session description.
+bool SdpContentsNone(SdpContentPredicate pred,
+                     const cricket::SessionDescription* desc);
+
+// Function that takes a single session description content with its
+// corresponding transport and can mutate the content and/or the transport.
+typedef std::function<void(cricket::ContentInfo*, cricket::TransportInfo*)>
+    SdpContentMutator;
+
+// Applies the mutator function over all contents in the given session
+// description.
+void SdpContentsForEach(SdpContentMutator fn,
+                        cricket::SessionDescription* desc);
+
+}  // namespace webrtc
+
+#endif  // PC_SDPUTILS_H_