remoting/protocol/content_description.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "remoting/protocol/content_description.h"
   6
   7 #include "base/logging.h"
   8 #include "base/strings/string_number_conversions.h"
   9 #include "remoting/base/constants.h"
  10 #include "remoting/protocol/authenticator.h"
  11 #include "remoting/protocol/name_value_map.h"
  12 #include "third_party/libjingle/source/talk/xmllite/xmlelement.h"
  13
  14 using buzz::QName;
  15 using buzz::XmlElement;
  16
  17 namespace remoting {
  18 namespace protocol {
  19
  20 const char ContentDescription::kChromotingContentName[] = "chromoting";
  21
  22 namespace {
  23
  24 const char kDefaultNs[] = "";
  25
  26 // Following constants are used to format session description in XML.
  27 const char kDescriptionTag[] = "description";
  28 const char kControlTag[] = "control";
  29 const char kEventTag[] = "event";
  30 const char kVideoTag[] = "video";
  31 const char kAudioTag[] = "audio";
  32 const char kDeprecatedResolutionTag[] = "initial-resolution";
  33
  34 const char kTransportAttr[] = "transport";
  35 const char kVersionAttr[] = "version";
  36 const char kCodecAttr[] = "codec";
  37 const char kDeprecatedWidthAttr[] = "width";
  38 const char kDeprecatedHeightAttr[] = "height";
  39
  40 const NameMapElement<ChannelConfig::TransportType> kTransports[] = {
  41   { ChannelConfig::TRANSPORT_STREAM, "stream" },
  42   { ChannelConfig::TRANSPORT_MUX_STREAM, "mux-stream" },
  43   { ChannelConfig::TRANSPORT_DATAGRAM, "datagram" },
  44   { ChannelConfig::TRANSPORT_NONE, "none" },
  45 };
  46
  47 const NameMapElement<ChannelConfig::Codec> kCodecs[] = {
  48   { ChannelConfig::CODEC_VERBATIM, "verbatim" },
  49   { ChannelConfig::CODEC_VP8, "vp8" },
  50   { ChannelConfig::CODEC_VP9, "vp9" },
  51   { ChannelConfig::CODEC_ZIP, "zip" },
  52   { ChannelConfig::CODEC_OPUS, "opus" },
  53   { ChannelConfig::CODEC_SPEEX, "speex" },
  54 };
  55
  56 // Format a channel configuration tag for chromotocol session description,
  57 // e.g. for video channel:
  58 //    <video transport="stream" version="1" codec="vp8" />
  59 XmlElement* FormatChannelConfig(const ChannelConfig& config,
  60                                 const std::string& tag_name) {
  61   XmlElement* result = new XmlElement(
  62       QName(kChromotingXmlNamespace, tag_name));
  63
  64   result->AddAttr(QName(kDefaultNs, kTransportAttr),
  65                   ValueToName(kTransports, config.transport));
  66
  67   if (config.transport != ChannelConfig::TRANSPORT_NONE) {
  68     result->AddAttr(QName(kDefaultNs, kVersionAttr),
  69                     base::IntToString(config.version));
  70
  71     if (config.codec != ChannelConfig::CODEC_UNDEFINED) {
  72       result->AddAttr(QName(kDefaultNs, kCodecAttr),
  73                       ValueToName(kCodecs, config.codec));
  74     }
  75   }
  76
  77   return result;
  78 }
  79
  80 // Returns false if the element is invalid.
  81 bool ParseChannelConfig(const XmlElement* element, bool codec_required,
  82                         ChannelConfig* config) {
  83   if (!NameToValue(
  84           kTransports, element->Attr(QName(kDefaultNs, kTransportAttr)),
  85           &config->transport)) {
  86     return false;
  87   }
  88
  89   // Version is not required when transport="none".
  90   if (config->transport != ChannelConfig::TRANSPORT_NONE) {
  91     if (!base::StringToInt(element->Attr(QName(kDefaultNs, kVersionAttr)),
  92                            &config->version)) {
  93       return false;
  94     }
  95
  96     // Codec is not required when transport="none".
  97     if (codec_required) {
  98       if (!NameToValue(kCodecs, element->Attr(QName(kDefaultNs, kCodecAttr)),
  99                        &config->codec)) {
 100         return false;
 101       }
 102     } else {
 103       config->codec = ChannelConfig::CODEC_UNDEFINED;
 104     }
 105   } else {
 106     config->version = 0;
 107     config->codec = ChannelConfig::CODEC_UNDEFINED;
 108   }
 109
 110   return true;
 111 }
 112
 113 }  // namespace
 114
 115 ContentDescription::ContentDescription(
 116     scoped_ptr<CandidateSessionConfig> config,
 117     scoped_ptr<buzz::XmlElement> authenticator_message)
 118     : candidate_config_(config.Pass()),
 119       authenticator_message_(authenticator_message.Pass()) {
 120 }
 121
 122 ContentDescription::~ContentDescription() { }
 123
 124 ContentDescription* ContentDescription::Copy() const {
 125   if (!candidate_config_.get() || !authenticator_message_.get()) {
 126     return NULL;
 127   }
 128   scoped_ptr<XmlElement> message(new XmlElement(*authenticator_message_));
 129   return new ContentDescription(candidate_config_->Clone(), message.Pass());
 130 }
 131
 132 // ToXml() creates content description for chromoting session. The
 133 // description looks as follows:
 134 //   <description xmlns="google:remoting">
 135 //     <control transport="stream" version="1" />
 136 //     <event transport="datagram" version="1" />
 137 //     <video transport="stream" codec="vp8" version="1" />
 138 //     <audio transport="stream" codec="opus" version="1" />
 139 //     <authentication>
 140 //      Message created by Authenticator implementation.
 141 //     </authentication>
 142 //   </description>
 143 //
 144 XmlElement* ContentDescription::ToXml() const {
 145   XmlElement* root = new XmlElement(
 146       QName(kChromotingXmlNamespace, kDescriptionTag), true);
 147
 148   std::list<ChannelConfig>::const_iterator it;
 149
 150   for (it = config()->control_configs().begin();
 151        it != config()->control_configs().end(); ++it) {
 152     root->AddElement(FormatChannelConfig(*it, kControlTag));
 153   }
 154
 155   for (it = config()->event_configs().begin();
 156        it != config()->event_configs().end(); ++it) {
 157     root->AddElement(FormatChannelConfig(*it, kEventTag));
 158   }
 159
 160   for (it = config()->video_configs().begin();
 161        it != config()->video_configs().end(); ++it) {
 162     root->AddElement(FormatChannelConfig(*it, kVideoTag));
 163   }
 164
 165   for (it = config()->audio_configs().begin();
 166        it != config()->audio_configs().end(); ++it) {
 167     ChannelConfig config = *it;
 168     root->AddElement(FormatChannelConfig(config, kAudioTag));
 169   }
 170
 171   // Older endpoints require an initial-resolution tag, but otherwise ignore it.
 172   XmlElement* resolution_tag = new XmlElement(
 173       QName(kChromotingXmlNamespace, kDeprecatedResolutionTag));
 174   resolution_tag->AddAttr(QName(kDefaultNs, kDeprecatedWidthAttr), "640");
 175   resolution_tag->AddAttr(QName(kDefaultNs, kDeprecatedHeightAttr), "480");
 176   root->AddElement(resolution_tag);
 177
 178   if (authenticator_message_.get()) {
 179     DCHECK(Authenticator::IsAuthenticatorMessage(authenticator_message_.get()));
 180     root->AddElement(new XmlElement(*authenticator_message_));
 181   }
 182
 183   return root;
 184 }
 185
 186 // static
 187 // Adds the channel configs corresponding to |tag_name|,
 188 // found in |element|, to |configs|.
 189 bool ContentDescription::ParseChannelConfigs(
 190     const XmlElement* const element,
 191     const char tag_name[],
 192     bool codec_required,
 193     bool optional,
 194     std::list<ChannelConfig>* const configs) {
 195
 196   QName tag(kChromotingXmlNamespace, tag_name);
 197   const XmlElement* child = element->FirstNamed(tag);
 198   while (child) {
 199     ChannelConfig channel_config;
 200     if (ParseChannelConfig(child, codec_required, &channel_config)) {
 201       configs->push_back(channel_config);
 202     }
 203     child = child->NextNamed(tag);
 204   }
 205   if (optional && configs->empty()) {
 206       // If there's no mention of the tag, implicitly assume disabled channel.
 207       configs->push_back(ChannelConfig::None());
 208   }
 209   return true;
 210 }
 211
 212 // static
 213 scoped_ptr<ContentDescription> ContentDescription::ParseXml(
 214     const XmlElement* element) {
 215   if (element->Name() != QName(kChromotingXmlNamespace, kDescriptionTag)) {
 216     LOG(ERROR) << "Invalid description: " << element->Str();
 217     return scoped_ptr<ContentDescription>();
 218   }
 219   scoped_ptr<CandidateSessionConfig> config(
 220       CandidateSessionConfig::CreateEmpty());
 221   if (!ParseChannelConfigs(element, kControlTag, false, false,
 222                            config->mutable_control_configs()) ||
 223       !ParseChannelConfigs(element, kEventTag, false, false,
 224                            config->mutable_event_configs()) ||
 225       !ParseChannelConfigs(element, kVideoTag, true, false,
 226                            config->mutable_video_configs()) ||
 227       !ParseChannelConfigs(element, kAudioTag, true, true,
 228                            config->mutable_audio_configs())) {
 229     return scoped_ptr<ContentDescription>();
 230   }
 231
 232   scoped_ptr<XmlElement> authenticator_message;
 233   const XmlElement* child = Authenticator::FindAuthenticatorMessage(element);
 234   if (child)
 235     authenticator_message.reset(new XmlElement(*child));
 236
 237   return scoped_ptr<ContentDescription>(
 238       new ContentDescription(config.Pass(), authenticator_message.Pass()));
 239 }
 240
 241 }  // namespace protocol
 242 }  // namespace remoting