talk/examples/android/src/org/appspot/apprtc/RoomParametersFetcher.java - platform/external/webrtc - Git at Google

 /*
  * libjingle
  * Copyright 2014, Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  *  1. Redistributions of source code must retain the above copyright notice,
  *     this list of conditions and the following disclaimer.
  *  2. Redistributions in binary form must reproduce the above copyright notice,
  *     this list of conditions and the following disclaimer in the documentation
  *     and/or other materials provided with the distribution.
  *  3. The name of the author may not be used to endorse or promote products
  *     derived from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 package org.appspot.apprtc;

 import org.appspot.apprtc.AppRTCClient.SignalingParameters;
 import org.appspot.apprtc.util.AsyncHttpURLConnection;
 import org.appspot.apprtc.util.AsyncHttpURLConnection.AsyncHttpEvents;

 import android.util.Log;

 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;
 import org.webrtc.IceCandidate;
 import org.webrtc.MediaConstraints;
 import org.webrtc.PeerConnection;
 import org.webrtc.SessionDescription;

 import java.io.IOException;
 import java.io.InputStream;
 import java.net.URL;
 import java.net.URLConnection;
 import java.util.LinkedList;
 import java.util.Scanner;

 /**
  * AsyncTask that converts an AppRTC room URL into the set of signaling
  * parameters to use with that room.
  */
 public class RoomParametersFetcher {
   private static final String TAG = "RoomRTCClient";
   private final RoomParametersFetcherEvents events;
   private final boolean loopback;
   private final String registerUrl;
   private AsyncHttpURLConnection httpConnection;

   /**
    * Room parameters fetcher callbacks.
    */
   public static interface RoomParametersFetcherEvents {
     /**
      * Callback fired once the room's signaling parameters
      * SignalingParameters are extracted.
      */
     public void onSignalingParametersReady(final SignalingParameters params);

     /**
      * Callback for room parameters extraction error.
      */
     public void onSignalingParametersError(final String description);
   }

   public RoomParametersFetcher(boolean loopback, String registerUrl,
       final RoomParametersFetcherEvents events) {
     Log.d(TAG, "Connecting to room: " + registerUrl);
     this.loopback = loopback;
     this.registerUrl = registerUrl;
     this.events = events;

     httpConnection = new AsyncHttpURLConnection("POST", registerUrl, null,
       new AsyncHttpEvents() {
         @Override
         public void OnHttpError(String errorMessage) {
           Log.e(TAG, "Room connection error: " + errorMessage);
           events.onSignalingParametersError(errorMessage);
         }

         @Override
         public void OnHttpComplete(String response) {
           RoomHttpResponseParse(response);
         }
       });
     httpConnection.send();
   }

   private void RoomHttpResponseParse(String response) {
     Log.d(TAG, "Room response: " + response);
     try {
       LinkedList<IceCandidate> iceCandidates = null;
       SessionDescription offerSdp = null;
       JSONObject roomJson = new JSONObject(response);

       String result = roomJson.getString("result");
       if (!result.equals("SUCCESS")) {
         events.onSignalingParametersError("Room response error: " + result);
         return;
       }
       response = roomJson.getString("params");
       roomJson = new JSONObject(response);
       String roomId = roomJson.getString("room_id");
       String clientId = roomJson.getString("client_id");
       String wssUrl = roomJson.getString("wss_url");
       String wssPostUrl = roomJson.getString("wss_post_url");
       boolean initiator = (roomJson.getBoolean("is_initiator"));
       String roomUrl =
           registerUrl.substring(0, registerUrl.indexOf("/register"));
       if (!initiator) {
         iceCandidates = new LinkedList<IceCandidate>();
         String messagesString = roomJson.getString("messages");
         JSONArray messages = new JSONArray(messagesString);
         for (int i = 0; i < messages.length(); ++i) {
           String messageString = messages.getString(i);
           JSONObject message = new JSONObject(messageString);
           String messageType = message.getString("type");
           Log.d(TAG, "GAE->C #" + i + " : " + messageString);
           if (messageType.equals("offer")) {
             offerSdp = new SessionDescription(
                 SessionDescription.Type.fromCanonicalForm(messageType),
                 message.getString("sdp"));
           } else if (messageType.equals("candidate")) {
             IceCandidate candidate = new IceCandidate(
                 message.getString("id"),
                 message.getInt("label"),
                 message.getString("candidate"));
             iceCandidates.add(candidate);
           } else {
             Log.e(TAG, "Unknown message: " + messageString);
           }
         }
       }
       Log.d(TAG, "RoomId: " + roomId + ". ClientId: " + clientId);
       Log.d(TAG, "Initiator: " + initiator);
       Log.d(TAG, "Room url: " + roomUrl);
       Log.d(TAG, "WSS url: " + wssUrl);
       Log.d(TAG, "WSS POST url: " + wssPostUrl);

       LinkedList<PeerConnection.IceServer> iceServers =
           iceServersFromPCConfigJSON(roomJson.getString("pc_config"));
       boolean isTurnPresent = false;
       for (PeerConnection.IceServer server : iceServers) {
         Log.d(TAG, "IceServer: " + server);
         if (server.uri.startsWith("turn:")) {
           isTurnPresent = true;
           break;
         }
       }
       if (!isTurnPresent) {
         LinkedList<PeerConnection.IceServer> turnServers =
             requestTurnServers(roomJson.getString("turn_url"));
         for (PeerConnection.IceServer turnServer : turnServers) {
           Log.d(TAG, "TurnServer: " + turnServer);
           iceServers.add(turnServer);
         }
       }

       MediaConstraints pcConstraints = constraintsFromJSON(
           roomJson.getString("pc_constraints"));
       addDTLSConstraintIfMissing(pcConstraints, loopback);
       Log.d(TAG, "pcConstraints: " + pcConstraints);
       MediaConstraints videoConstraints = constraintsFromJSON(
           getAVConstraints("video",
               roomJson.getString("media_constraints")));
       Log.d(TAG, "videoConstraints: " + videoConstraints);
       MediaConstraints audioConstraints = constraintsFromJSON(
           getAVConstraints("audio",
               roomJson.getString("media_constraints")));
       Log.d(TAG, "audioConstraints: " + audioConstraints);

       SignalingParameters params = new SignalingParameters(
           iceServers, initiator,
           pcConstraints, videoConstraints, audioConstraints,
           roomUrl, roomId, clientId,
           wssUrl, wssPostUrl,
           offerSdp, iceCandidates);
       events.onSignalingParametersReady(params);
     } catch (JSONException e) {
       events.onSignalingParametersError(
           "Room JSON parsing error: " + e.toString());
     } catch (IOException e) {
       events.onSignalingParametersError("Room IO error: " + e.toString());
     }
   }

   // Mimic Chrome and set DtlsSrtpKeyAgreement to true if not set to false by
   // the web-app.
   private void addDTLSConstraintIfMissing(
       MediaConstraints pcConstraints, boolean loopback) {
     for (MediaConstraints.KeyValuePair pair : pcConstraints.mandatory) {
       if (pair.getKey().equals("DtlsSrtpKeyAgreement")) {
         return;
       }
     }
     for (MediaConstraints.KeyValuePair pair : pcConstraints.optional) {
       if (pair.getKey().equals("DtlsSrtpKeyAgreement")) {
         return;
       }
     }
     // DTLS isn't being specified (e.g. for debug=loopback calls), so enable
     // it for normal calls and disable for loopback calls.
     if (loopback) {
       pcConstraints.optional.add(
           new MediaConstraints.KeyValuePair("DtlsSrtpKeyAgreement", "false"));
     } else {
       pcConstraints.optional.add(
           new MediaConstraints.KeyValuePair("DtlsSrtpKeyAgreement", "true"));
     }
   }

   // Return the constraints specified for |type| of "audio" or "video" in
   // |mediaConstraintsString|.
   private String getAVConstraints (
     String type, String mediaConstraintsString) throws JSONException {
     JSONObject json = new JSONObject(mediaConstraintsString);
     // Tricky handling of values that are allowed to be (boolean or
     // MediaTrackConstraints) by the getUserMedia() spec.  There are three
     // cases below.
     if (!json.has(type) || !json.optBoolean(type, true)) {
       // Case 1: "audio"/"video" is not present, or is an explicit "false"
       // boolean.
       return null;
     }
     if (json.optBoolean(type, false)) {
       // Case 2: "audio"/"video" is an explicit "true" boolean.
       return "{\"mandatory\": {}, \"optional\": []}";
     }
     // Case 3: "audio"/"video" is an object.
     return json.getJSONObject(type).toString();
   }

   private MediaConstraints constraintsFromJSON(String jsonString)
       throws JSONException {
     if (jsonString == null) {
       return null;
     }
     MediaConstraints constraints = new MediaConstraints();
     JSONObject json = new JSONObject(jsonString);
     JSONObject mandatoryJSON = json.optJSONObject("mandatory");
     if (mandatoryJSON != null) {
       JSONArray mandatoryKeys = mandatoryJSON.names();
       if (mandatoryKeys != null) {
         for (int i = 0; i < mandatoryKeys.length(); ++i) {
           String key = mandatoryKeys.getString(i);
           String value = mandatoryJSON.getString(key);
           constraints.mandatory.add(
               new MediaConstraints.KeyValuePair(key, value));
         }
       }
     }
     JSONArray optionalJSON = json.optJSONArray("optional");
     if (optionalJSON != null) {
       for (int i = 0; i < optionalJSON.length(); ++i) {
         JSONObject keyValueDict = optionalJSON.getJSONObject(i);
         String key = keyValueDict.names().getString(0);
         String value = keyValueDict.getString(key);
         constraints.optional.add(
             new MediaConstraints.KeyValuePair(key, value));
       }
     }
     return constraints;
   }

   // Requests & returns a TURN ICE Server based on a request URL.  Must be run
   // off the main thread!
   private LinkedList<PeerConnection.IceServer> requestTurnServers(String url)
       throws IOException, JSONException {
     LinkedList<PeerConnection.IceServer> turnServers =
         new LinkedList<PeerConnection.IceServer>();
     Log.d(TAG, "Request TURN from: " + url);
     URLConnection connection = (new URL(url)).openConnection();
     connection.addRequestProperty("user-agent", "Mozilla/5.0");
     connection.addRequestProperty("origin", "https://apprtc.appspot.com");
     String response = drainStream(connection.getInputStream());
     Log.d(TAG, "TURN response: " + response);
     JSONObject responseJSON = new JSONObject(response);
     String username = responseJSON.getString("username");
     String password = responseJSON.getString("password");
     JSONArray turnUris = responseJSON.getJSONArray("uris");
     for (int i = 0; i < turnUris.length(); i++) {
       String uri = turnUris.getString(i);
       turnServers.add(new PeerConnection.IceServer(uri, username, password));
     }
     return turnServers;
   }

   // Return the list of ICE servers described by a WebRTCPeerConnection
   // configuration string.
   private LinkedList<PeerConnection.IceServer> iceServersFromPCConfigJSON(
       String pcConfig) throws JSONException {
     JSONObject json = new JSONObject(pcConfig);
     JSONArray servers = json.getJSONArray("iceServers");
     LinkedList<PeerConnection.IceServer> ret =
         new LinkedList<PeerConnection.IceServer>();
     for (int i = 0; i < servers.length(); ++i) {
       JSONObject server = servers.getJSONObject(i);
       String url = server.getString("urls");
       String credential =
           server.has("credential") ? server.getString("credential") : "";
       ret.add(new PeerConnection.IceServer(url, "", credential));
     }
     return ret;
   }

   // Return the contents of an InputStream as a String.
   private String drainStream(InputStream in) {
     Scanner s = new Scanner(in).useDelimiter("\\A");
     return s.hasNext() ? s.next() : "";
   }

 }
	/*
	* libjingle
	* Copyright 2014, Google Inc.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are met:
	*
	* 1. Redistributions of source code must retain the above copyright notice,
	* this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright notice,
	* this list of conditions and the following disclaimer in the documentation
	* and/or other materials provided with the distribution.
	* 3. The name of the author may not be used to endorse or promote products
	* derived from this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
	* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
	* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
	* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
	* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
	* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
	* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/
	package org.appspot.apprtc;

	import org.appspot.apprtc.AppRTCClient.SignalingParameters;
	import org.appspot.apprtc.util.AsyncHttpURLConnection;
	import org.appspot.apprtc.util.AsyncHttpURLConnection.AsyncHttpEvents;

	import android.util.Log;

	import org.json.JSONArray;
	import org.json.JSONException;
	import org.json.JSONObject;
	import org.webrtc.IceCandidate;
	import org.webrtc.MediaConstraints;
	import org.webrtc.PeerConnection;
	import org.webrtc.SessionDescription;

	import java.io.IOException;
	import java.io.InputStream;
	import java.net.URL;
	import java.net.URLConnection;
	import java.util.LinkedList;
	import java.util.Scanner;

	/**
	* AsyncTask that converts an AppRTC room URL into the set of signaling
	* parameters to use with that room.
	*/
	public class RoomParametersFetcher {
	private static final String TAG = "RoomRTCClient";
	private final RoomParametersFetcherEvents events;
	private final boolean loopback;
	private final String registerUrl;
	private AsyncHttpURLConnection httpConnection;

	/**
	* Room parameters fetcher callbacks.
	*/
	public static interface RoomParametersFetcherEvents {
	/**
	* Callback fired once the room's signaling parameters
	* SignalingParameters are extracted.
	*/
	public void onSignalingParametersReady(final SignalingParameters params);

	/**
	* Callback for room parameters extraction error.
	*/
	public void onSignalingParametersError(final String description);
	}

	public RoomParametersFetcher(boolean loopback, String registerUrl,
	final RoomParametersFetcherEvents events) {
	Log.d(TAG, "Connecting to room: " + registerUrl);
	this.loopback = loopback;
	this.registerUrl = registerUrl;
	this.events = events;

	httpConnection = new AsyncHttpURLConnection("POST", registerUrl, null,
	new AsyncHttpEvents() {
	@Override
	public void OnHttpError(String errorMessage) {
	Log.e(TAG, "Room connection error: " + errorMessage);
	events.onSignalingParametersError(errorMessage);
	}

	@Override
	public void OnHttpComplete(String response) {
	RoomHttpResponseParse(response);
	}
	});
	httpConnection.send();
	}

	private void RoomHttpResponseParse(String response) {
	Log.d(TAG, "Room response: " + response);
	try {
	LinkedList<IceCandidate> iceCandidates = null;
	SessionDescription offerSdp = null;
	JSONObject roomJson = new JSONObject(response);

	String result = roomJson.getString("result");
	if (!result.equals("SUCCESS")) {
	events.onSignalingParametersError("Room response error: " + result);
	return;
	}
	response = roomJson.getString("params");
	roomJson = new JSONObject(response);
	String roomId = roomJson.getString("room_id");
	String clientId = roomJson.getString("client_id");
	String wssUrl = roomJson.getString("wss_url");
	String wssPostUrl = roomJson.getString("wss_post_url");
	boolean initiator = (roomJson.getBoolean("is_initiator"));
	String roomUrl =
	registerUrl.substring(0, registerUrl.indexOf("/register"));
	if (!initiator) {
	iceCandidates = new LinkedList<IceCandidate>();
	String messagesString = roomJson.getString("messages");
	JSONArray messages = new JSONArray(messagesString);
	for (int i = 0; i < messages.length(); ++i) {
	String messageString = messages.getString(i);
	JSONObject message = new JSONObject(messageString);
	String messageType = message.getString("type");
	Log.d(TAG, "GAE->C #" + i + " : " + messageString);
	if (messageType.equals("offer")) {
	offerSdp = new SessionDescription(
	SessionDescription.Type.fromCanonicalForm(messageType),
	message.getString("sdp"));
	} else if (messageType.equals("candidate")) {
	IceCandidate candidate = new IceCandidate(
	message.getString("id"),
	message.getInt("label"),
	message.getString("candidate"));
	iceCandidates.add(candidate);
	} else {
	Log.e(TAG, "Unknown message: " + messageString);
	}
	}
	}
	Log.d(TAG, "RoomId: " + roomId + ". ClientId: " + clientId);
	Log.d(TAG, "Initiator: " + initiator);
	Log.d(TAG, "Room url: " + roomUrl);
	Log.d(TAG, "WSS url: " + wssUrl);
	Log.d(TAG, "WSS POST url: " + wssPostUrl);

	LinkedList<PeerConnection.IceServer> iceServers =
	iceServersFromPCConfigJSON(roomJson.getString("pc_config"));
	boolean isTurnPresent = false;
	for (PeerConnection.IceServer server : iceServers) {
	Log.d(TAG, "IceServer: " + server);
	if (server.uri.startsWith("turn:")) {
	isTurnPresent = true;
	break;
	}
	}
	if (!isTurnPresent) {
	LinkedList<PeerConnection.IceServer> turnServers =
	requestTurnServers(roomJson.getString("turn_url"));
	for (PeerConnection.IceServer turnServer : turnServers) {
	Log.d(TAG, "TurnServer: " + turnServer);
	iceServers.add(turnServer);
	}
	}

	MediaConstraints pcConstraints = constraintsFromJSON(
	roomJson.getString("pc_constraints"));
	addDTLSConstraintIfMissing(pcConstraints, loopback);
	Log.d(TAG, "pcConstraints: " + pcConstraints);
	MediaConstraints videoConstraints = constraintsFromJSON(
	getAVConstraints("video",
	roomJson.getString("media_constraints")));
	Log.d(TAG, "videoConstraints: " + videoConstraints);
	MediaConstraints audioConstraints = constraintsFromJSON(
	getAVConstraints("audio",
	roomJson.getString("media_constraints")));
	Log.d(TAG, "audioConstraints: " + audioConstraints);

	SignalingParameters params = new SignalingParameters(
	iceServers, initiator,
	pcConstraints, videoConstraints, audioConstraints,
	roomUrl, roomId, clientId,
	wssUrl, wssPostUrl,
	offerSdp, iceCandidates);
	events.onSignalingParametersReady(params);
	} catch (JSONException e) {
	events.onSignalingParametersError(
	"Room JSON parsing error: " + e.toString());
	} catch (IOException e) {
	events.onSignalingParametersError("Room IO error: " + e.toString());
	}
	}

	// Mimic Chrome and set DtlsSrtpKeyAgreement to true if not set to false by
	// the web-app.
	private void addDTLSConstraintIfMissing(
	MediaConstraints pcConstraints, boolean loopback) {
	for (MediaConstraints.KeyValuePair pair : pcConstraints.mandatory) {
	if (pair.getKey().equals("DtlsSrtpKeyAgreement")) {
	return;
	}
	}
	for (MediaConstraints.KeyValuePair pair : pcConstraints.optional) {
	if (pair.getKey().equals("DtlsSrtpKeyAgreement")) {
	return;
	}
	}
	// DTLS isn't being specified (e.g. for debug=loopback calls), so enable
	// it for normal calls and disable for loopback calls.
	if (loopback) {
	pcConstraints.optional.add(
	new MediaConstraints.KeyValuePair("DtlsSrtpKeyAgreement", "false"));
	} else {
	pcConstraints.optional.add(
	new MediaConstraints.KeyValuePair("DtlsSrtpKeyAgreement", "true"));
	}
	}

	// Return the constraints specified for \|type\| of "audio" or "video" in
	// \|mediaConstraintsString\|.
	private String getAVConstraints (
	String type, String mediaConstraintsString) throws JSONException {
	JSONObject json = new JSONObject(mediaConstraintsString);
	// Tricky handling of values that are allowed to be (boolean or
	// MediaTrackConstraints) by the getUserMedia() spec. There are three
	// cases below.
	if (!json.has(type) \|\| !json.optBoolean(type, true)) {
	// Case 1: "audio"/"video" is not present, or is an explicit "false"
	// boolean.
	return null;
	}
	if (json.optBoolean(type, false)) {
	// Case 2: "audio"/"video" is an explicit "true" boolean.
	return "{\"mandatory\": {}, \"optional\": []}";
	}
	// Case 3: "audio"/"video" is an object.
	return json.getJSONObject(type).toString();
	}

	private MediaConstraints constraintsFromJSON(String jsonString)
	throws JSONException {
	if (jsonString == null) {
	return null;
	}
	MediaConstraints constraints = new MediaConstraints();
	JSONObject json = new JSONObject(jsonString);
	JSONObject mandatoryJSON = json.optJSONObject("mandatory");
	if (mandatoryJSON != null) {
	JSONArray mandatoryKeys = mandatoryJSON.names();
	if (mandatoryKeys != null) {
	for (int i = 0; i < mandatoryKeys.length(); ++i) {
	String key = mandatoryKeys.getString(i);
	String value = mandatoryJSON.getString(key);
	constraints.mandatory.add(
	new MediaConstraints.KeyValuePair(key, value));
	}
	}
	}
	JSONArray optionalJSON = json.optJSONArray("optional");
	if (optionalJSON != null) {
	for (int i = 0; i < optionalJSON.length(); ++i) {
	JSONObject keyValueDict = optionalJSON.getJSONObject(i);
	String key = keyValueDict.names().getString(0);
	String value = keyValueDict.getString(key);
	constraints.optional.add(
	new MediaConstraints.KeyValuePair(key, value));
	}
	}
	return constraints;
	}

	// Requests & returns a TURN ICE Server based on a request URL. Must be run
	// off the main thread!
	private LinkedList<PeerConnection.IceServer> requestTurnServers(String url)
	throws IOException, JSONException {
	LinkedList<PeerConnection.IceServer> turnServers =
	new LinkedList<PeerConnection.IceServer>();
	Log.d(TAG, "Request TURN from: " + url);
	URLConnection connection = (new URL(url)).openConnection();
	connection.addRequestProperty("user-agent", "Mozilla/5.0");
	connection.addRequestProperty("origin", "https://apprtc.appspot.com");
	String response = drainStream(connection.getInputStream());
	Log.d(TAG, "TURN response: " + response);
	JSONObject responseJSON = new JSONObject(response);
	String username = responseJSON.getString("username");
	String password = responseJSON.getString("password");
	JSONArray turnUris = responseJSON.getJSONArray("uris");
	for (int i = 0; i < turnUris.length(); i++) {
	String uri = turnUris.getString(i);
	turnServers.add(new PeerConnection.IceServer(uri, username, password));
	}
	return turnServers;
	}

	// Return the list of ICE servers described by a WebRTCPeerConnection
	// configuration string.
	private LinkedList<PeerConnection.IceServer> iceServersFromPCConfigJSON(
	String pcConfig) throws JSONException {
	JSONObject json = new JSONObject(pcConfig);
	JSONArray servers = json.getJSONArray("iceServers");
	LinkedList<PeerConnection.IceServer> ret =
	new LinkedList<PeerConnection.IceServer>();
	for (int i = 0; i < servers.length(); ++i) {
	JSONObject server = servers.getJSONObject(i);
	String url = server.getString("urls");
	String credential =
	server.has("credential") ? server.getString("credential") : "";
	ret.add(new PeerConnection.IceServer(url, "", credential));
	}
	return ret;
	}

	// Return the contents of an InputStream as a String.
	private String drainStream(InputStream in) {
	Scanner s = new Scanner(in).useDelimiter("\\A");
	return s.hasNext() ? s.next() : "";
	}

	}