sl4a/Common/src/com/googlecode/android_scripting/jsonrpc/JsonRpcServer.java

/*
 * Copyright (C) 2016 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package com.googlecode.android_scripting.jsonrpc;

import java.io.BufferedReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Map;

import org.json.JSONArray;
import org.json.JSONObject;

import com.googlecode.android_scripting.Log;
import com.googlecode.android_scripting.SimpleServer;
import com.googlecode.android_scripting.rpc.MethodDescriptor;
import com.googlecode.android_scripting.rpc.RpcError;

/**
 * A JSON RPC server that forwards RPC calls to a specified receiver object.
 *
 * @author Damon Kohler (damonkohler@gmail.com)
 */
public class JsonRpcServer extends SimpleServer {

    private static final String CMD_CLOSE_SESSION = "closeSl4aSession";

    private final RpcReceiverManagerFactory mRpcReceiverManagerFactory;

    // private final String mHandshake;

    /**
     * Construct a {@link JsonRpcServer} connected to the provided {@link RpcReceiverManager}.
     *
     * @param managerFactory the {@link RpcReceiverManager} to register with the server
     * @param handshake the secret handshake required for authorization to use this server
     */
    public JsonRpcServer(RpcReceiverManagerFactory managerFactory, String handshake) {
        // mHandshake = handshake;
        mRpcReceiverManagerFactory = managerFactory;
    }

    @Override
    public void shutdown() {
        super.shutdown();
        // Notify all RPC receiving objects. They may have to clean up some of their state.
        for (RpcReceiverManager manager : mRpcReceiverManagerFactory.getRpcReceiverManagers()
                .values()) {
            manager.shutdown();
        }
    }

    @Override
    protected void handleRPCConnection(Socket sock, Integer UID, BufferedReader reader,
            PrintWriter writer) throws Exception {
        RpcReceiverManager receiverManager = null;
        Map<Integer, RpcReceiverManager> mgrs = mRpcReceiverManagerFactory.getRpcReceiverManagers();
        synchronized (mgrs) {
            Log.d("UID " + UID);
            Log.d("manager map keys: "
                    + mRpcReceiverManagerFactory.getRpcReceiverManagers().keySet());
            if (mgrs.containsKey(UID)) {
                Log.d("Look up existing session");
                receiverManager = mgrs.get(UID);
            } else {
                Log.d("Create a new session");
                receiverManager = mRpcReceiverManagerFactory.create(UID);
            }
        }
        // boolean passedAuthentication = false;
        String data;
        while ((data = reader.readLine()) != null) {
            Log.v("Session " + UID + " Received: " + data);
            JSONObject request = new JSONObject(data);
            int id = request.getInt("id");
            String method = request.getString("method");
            JSONArray params = request.getJSONArray("params");

            MethodDescriptor rpc = receiverManager.getMethodDescriptor(method);
            if (rpc == null) {
                send(writer, JsonRpcResult.error(id, new RpcError("Unknown RPC: " + method)), UID);
                continue;
            }
            try {
                send(writer, JsonRpcResult.result(id, rpc.invoke(receiverManager, params)), UID);
            } catch (Throwable t) {
                Log.e("Invocation error.", t);
                send(writer, JsonRpcResult.error(id, t), UID);
            }
            if (method.equals(CMD_CLOSE_SESSION)) {
                Log.d("Got shutdown signal");
                synchronized (writer) {
                    receiverManager.shutdown();
                    reader.close();
                    writer.close();
                    sock.close();
                    shutdown();
                    mgrs.remove(UID);
                }
                return;
            }
        }
    }

    private void send(PrintWriter writer, JSONObject result, int UID) {
        writer.write(result + "\n");
        writer.flush();
        Log.v("Session " + UID + " Sent: " + result);
    }

    @Override
    protected void handleConnection(Socket socket) throws Exception {
    }
}