/* * Copyright (C) 2011 The Android Open Source Project * * 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. */ #ifndef ANDROID_ANDROID_DEVICE_H_ #define ANDROID_ANDROID_DEVICE_H_ /* * Encapsulates an exchange protocol between the emulator, and an Android device * that is connected to the host via USB. The communication is established over * a TCP port forwarding, enabled by ADB (always use 'adb -d forward ...' variant * of this command, so ADB will know to enable port forwarding on the connected * device, and not on the emulator's guest system). * * Exchange protocol contains two channel: * * - Query channel. * - Event channel. * * Both channels are implemented on top of TCP sockets that are connected to the * same port. * * I QUERY CHANNEL. * Query channel is intended to send queries to and receive responses from the * connected device. It is implemented on top of iolooper_xxx API (see iolooper.h) * because it must work outside of the main event loop. This is required to enable * proper initialization of components (such as sensors) that must be set up * before emulator enters the main loop. * * II EVENT CHANNEL. * Event channel is intended to listen on events sent from the device, and * asynchronously report them back to the client of this API by invoking an event * callback that was registered by the client. Event channel is implemented on * top of asyncXxx API (see android/async-utils.*). Note that using of asyncXxx * API limits the use of event channel to the time after the emulator has entered * its main event loop. The only exception is if event channel is connected from * android_device_connect_sync API, in which case iolooper_xxx API is used to * establish the connection. However, even in this case listening for events will * not be available until after the emulator enters its event loop, since event * listening always uses asyncXxx API. * * III. ESTABLISHING CONNECTION. * ADB port forwarding requires that the server socket is to be run on the device, * while emulator must use a client socket for communication. Thus, it's the * emulator that initiates the connection. * * There are two ways how emulator can initiate the connection: * * - Synchronous connection. * - Asynchronous connection. * * III.I SYNCHROUNOUS CONNECTION. * Synchronous connection is initiated via android_device_connect_sync API, and * completes synchronously. * * This API should be used when connection with the device is required at the time * of the call. For instance, when initializing sensor emulation, connection with * the device is required to properly set up the emulator before the guest system * starts, and before emulator enters its main event loop. * * III.II ASYNCHRONOUS CONNECTION. * Asynchronous connection is initiated via android_device_connect_async API. The * main difference with the synchronous connection is that this API will not fail * if connection is not immediately available. If connection is not available at * the time of the call, the API will schedule a retry (based on a timer), and * will continue reprying untill connection becomes available, or until an error * occurs that prevent further retries. * * This API should be used when ... Well, whenever appropriate. For instance, * sensor emulation will use this API to restore lost connection with the device. * * NOTE: Asynchronous connection will complete no sooner than the emulator enters * its main loop. * * IV EXCHANGE PROTOCOL. * Obviously, there must be some application running on the device, that implements * a socket server listening on the forwarded TCP port, and accepting the clients. * * IV.I Query vs. event channel. * The exchange protocol assumes, that when a channel is connected, it will * identify itself by sending a string containing channel type. Only after such * identification has been made the channel becomes available for use. * * IV.II Message format. * All data that is transferred in both directions over both channels are zero- * terminated strings. */ #include "qemu-common.h" #include "android/async-utils.h" #include "android/utils/debug.h" /* TCP port reserved for sensor emulation. */ #define AD_SENSOR_PORT 1968 /* Definis infinite timeout. */ #define AD_INFINITE_WAIT -1 /* Android device descriptor. */ typedef struct AndroidDevice AndroidDevice; /******************************************************************************** * Callback declarations *******************************************************************************/ /* Callback routine that is invoked when android device is connected, or failed * to connect. As discussed above, this callback is called when both, query and * event channels have been connected. This callback is used only for asynchronous * connections. * Param: * opaque - Opaque pointer that was passed to android_device_init API. * ad - Androd device descriptor for the connection. * failure - Zero indicates that connection with the device has been successfuly * established. Non-zero vaule passed in this parameter indicates a failure, * and contains 'errno'-reason for failure. */ typedef void (*device_connected_cb)(void* opaque, AndroidDevice* ad, int failure); /* Callback routine that is invoked on an event received in the event channel. * NOTE: It's important to check 'errno' in this callback. If 'errno' is set to * ENOMEM, this signals that buffer passed to android_device_listen was too small * to contain the entire event message. * Param: * opaque - Opaque pointer that was passed to android_device_init API. * ad - Androd device descriptor for the connection. * msg - Event message (a zero-terminated string) received from the device. * msgsize - Event message size (including zero-terminator). */ typedef void (*event_cb)(void* opaque, AndroidDevice* ad, char* msg, int msgsize); /* Callback routine that is invoked when an I/O failure occurs on a channel. * Note that this callback will not be invoked on connection failures. * Param: * opaque - Opaque pointer that was passed to android_device_init API. * ad - Android device instance * failure - Contains 'errno' indicating the reason for failure. */ typedef void (*io_failure_cb)(void* opaque, AndroidDevice* ad, int failure); /******************************************************************************** * Android Device API. *******************************************************************************/ /* Initializes android device descriptor. * Param: * opaque - An opaque pointer to associate with the descriptor. This pointer * will be passed to all callbacks (see above) that were invoked by the * initializing android device instance. * port - TCP port to use for connection. * on_io_failure - Callback to invoke when an I/O failure occurs on a channel * used by the initializing android device instance. Can be NULL. * Return: * Initialized android device descriptor on success, or NULL on failure. */ extern AndroidDevice* android_device_init(void* opaque, int port, io_failure_cb on_io_failure); /* Disconnects and destroys android device descriptor. * Param: * ad - Android device descriptor, returned from android_device_init API. * Note that memory allocated for this descriptor will be freed in this * routine. */ extern void android_device_destroy(AndroidDevice* ad); /* Synchronously connects to the device. See notes above for more details. * Param: * ad - Android device descriptor, returned from android_device_init API. * to - Milliseconds to wait for connection to be established. * Return: * Zero on success, or non-zero value on failure with 'errno' properly set. */ extern int android_device_connect_sync(AndroidDevice* ad, int to); /* Asynchronously connects to the device. See notes above for more details. * Param: * ad - Android device descriptor, returned from android_device_init API. * on_connected - Callback to invoke when connection is completed (i,e, both, * event, and query channels have been connected). This parameter can be * NULL. Note that connection errors will be also reported through this * callback. Also note that this callback will be invoked even if this * routine returns with a failure. * Return: * Zero on success, or non-zero value on failure with 'errno' properly set. */ extern int android_device_connect_async(AndroidDevice* ad, device_connected_cb on_connected); /* Disconnects from the android device. * Param: * ad - Android device descriptor, returned from android_device_init API. */ extern void android_device_disconnect(AndroidDevice* ad); /* Queries the device via query channel. * Param: * ad - Android device descriptor, returned from android_device_init API. * query - Zero-terminated query string. * buff, buffsize - Buffer where to receive the response to the query. * to - Milliseconds to wait for the entire query to complete. * Return: * Zero on success, or non-zero value on failure with 'errno' properly set: * - 0 Indicates that the server has failed the query. * - Anything else indicates an I/O error. */ extern int android_device_query(AndroidDevice* ad, const char* query, char* buff, size_t buffsize, int to); /* Start listening on the event channel. * Param: * ad - Android device descriptor, returned from android_device_init API. * buff, buffsize - Buffer where to receive the event message. * on_event - Callback to invoke on event. Note that this callback will be * invoked even if this routine returns with a failure. * Return: * Zero on success, or non-zero value on failure with 'errno' properly set. */ extern int android_device_listen(AndroidDevice* ad, char* buff, int buffsize, event_cb on_event); #endif /* ANDROID_ANDROID_DEVICE_H_ */