378 lines
11 KiB
C
378 lines
11 KiB
C
/*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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#include "config.h"
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#include "guacamole/client.h"
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#include "guacamole/error.h"
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#include "guacamole/socket.h"
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#include "guacamole/user.h"
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#include <pthread.h>
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#include <stdlib.h>
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/**
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* Data associated with an open socket which writes to all connected users of
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* a particular guac_client.
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*/
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typedef struct guac_socket_broadcast_data {
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/**
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* The guac_client whose connected users should receive all instructions
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* written to this socket.
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*/
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guac_client* client;
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/**
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* Lock which is acquired when an instruction is being written, and
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* released when the instruction is finished being written.
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*/
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pthread_mutex_t socket_lock;
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} guac_socket_broadcast_data;
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/**
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* Single chunk of data, to be broadcast to all users.
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*/
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typedef struct __write_chunk {
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/**
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* The buffer to write.
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*/
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const void* buffer;
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/**
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* The number of bytes in the buffer.
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*/
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size_t length;
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} __write_chunk;
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/**
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* Callback which handles read requests on the broadcast socket. This callback
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* always fails, as the broadcast socket is write-only; it cannot be read.
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*
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* @param socket
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* The broadcast socket to read from.
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*
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* @param buf
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* The buffer into which data should be read.
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*
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* @param count
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* The number of bytes to attempt to read.
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*
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* @return
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* The number of bytes read, or -1 if an error occurs. This implementation
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* always returns -1, as the broadcast socket is write-only and cannot be
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* read.
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*/
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static ssize_t __guac_socket_broadcast_read_handler(guac_socket* socket,
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void* buf, size_t count) {
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/* Broadcast socket reads are not allowed */
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return -1;
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}
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/**
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* Callback invoked by guac_client_foreach_user() which write a given chunk of
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* data to that user's socket. If the write attempt fails, the user is
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* signalled to stop with guac_user_stop().
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*
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* @param user
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* The user that the chunk of data should be written to.
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*
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* @param data
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* A pointer to a __write_chunk which describes the data to be written.
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*
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* @return
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* Always NULL.
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*/
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static void* __write_chunk_callback(guac_user* user, void* data) {
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__write_chunk* chunk = (__write_chunk*) data;
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/* Attempt write, disconnect on failure */
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if (guac_socket_write(user->socket, chunk->buffer, chunk->length))
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guac_user_stop(user);
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return NULL;
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}
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/**
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* Socket write handler which operates on each of the sockets of all connected
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* users. This write handler will always succeed, but any failing user-specific
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* writes will invoke guac_user_stop() on the failing user.
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*
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* @param socket
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* The socket to which the given data must be written.
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*
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* @param buf
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* The buffer containing the data to write.
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*
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* @param count
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* The number of bytes to attempt to write from the given buffer.
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*
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* @return
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* The number of bytes written, or -1 if an error occurs. This handler will
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* always succeed, and thus will always return the exact number of bytes
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* specified by count.
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*/
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static ssize_t __guac_socket_broadcast_write_handler(guac_socket* socket,
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const void* buf, size_t count) {
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guac_socket_broadcast_data* data =
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(guac_socket_broadcast_data*) socket->data;
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/* Build chunk */
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__write_chunk chunk;
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chunk.buffer = buf;
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chunk.length = count;
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/* Broadcast chunk to all users */
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guac_client_foreach_user(data->client, __write_chunk_callback, &chunk);
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return count;
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}
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/**
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* Callback which is invoked by guac_client_foreach_user() to flush all
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* pending data on the given user's socket. If an error occurs while flushing
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* a user's socket, that user is signalled to stop with guac_user_stop().
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*
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* @param user
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* The user whose socket should be flushed.
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*
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* @param data
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* Arbitrary data passed to guac_client_foreach_user(). This is not needed
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* by this callback, and should be left as NULL.
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*
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* @return
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* Always NULL.
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*/
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static void* __flush_callback(guac_user* user, void* data) {
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/* Attempt flush, disconnect on failure */
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if (guac_socket_flush(user->socket))
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guac_user_stop(user);
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return NULL;
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}
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/**
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* Socket flush handler which operates on each of the sockets of all connected
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* users. This flush handler will always succeed, but any failing user-specific
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* flush will invoke guac_user_stop() on the failing user.
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*
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* @param socket
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* The broadcast socket to flush.
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*
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* @return
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* Zero if the flush operation succeeds, non-zero if the operation fails.
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* This handler will always succeed, and thus will always return zero.
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*/
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static ssize_t __guac_socket_broadcast_flush_handler(guac_socket* socket) {
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guac_socket_broadcast_data* data =
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(guac_socket_broadcast_data*) socket->data;
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/* Flush all users */
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guac_client_foreach_user(data->client, __flush_callback, NULL);
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return 0;
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}
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/**
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* Callback which is invoked by guac_client_foreach_user() to lock the given
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* user's socket in preparation for the beginning of a Guacamole protocol
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* instruction.
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*
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* @param user
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* The user whose socket should be locked.
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*
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* @param data
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* Arbitrary data passed to guac_client_foreach_user(). This is not needed
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* by this callback, and should be left as NULL.
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*
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* @return
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* Always NULL.
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*/
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static void* __lock_callback(guac_user* user, void* data) {
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/* Lock socket */
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guac_socket_instruction_begin(user->socket);
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return NULL;
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}
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/**
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* Socket lock handler which acquires the socket locks of all connected users.
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* Socket-level locks are acquired in preparation for the beginning of a new
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* Guacamole instruction to ensure that parallel writes are only interleaved at
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* instruction boundaries.
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*
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* @param socket
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* The broadcast socket to lock.
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*/
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static void __guac_socket_broadcast_lock_handler(guac_socket* socket) {
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guac_socket_broadcast_data* data =
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(guac_socket_broadcast_data*) socket->data;
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/* Acquire exclusive access to socket */
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pthread_mutex_lock(&(data->socket_lock));
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/* Lock sockets of all users */
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guac_client_foreach_user(data->client, __lock_callback, NULL);
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}
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/**
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* Callback which is invoked by guac_client_foreach_user() to unlock the given
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* user's socket at the end of a Guacamole protocol instruction.
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*
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* @param user
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* The user whose socket should be unlocked.
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*
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* @param data
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* Arbitrary data passed to guac_client_foreach_user(). This is not needed
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* by this callback, and should be left as NULL.
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*
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* @return
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* Always NULL.
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*/
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static void* __unlock_callback(guac_user* user, void* data) {
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/* Unlock socket */
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guac_socket_instruction_end(user->socket);
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return NULL;
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}
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/**
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* Socket unlock handler which releases the socket locks of all connected users.
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* Socket-level locks are released after a Guacamole instruction has finished
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* being written.
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*
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* @param socket
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* The broadcast socket to unlock.
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*/
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static void __guac_socket_broadcast_unlock_handler(guac_socket* socket) {
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guac_socket_broadcast_data* data =
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(guac_socket_broadcast_data*) socket->data;
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/* Unlock sockets of all users */
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guac_client_foreach_user(data->client, __unlock_callback, NULL);
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/* Relinquish exclusive access to socket */
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pthread_mutex_unlock(&(data->socket_lock));
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}
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/**
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* Callback which handles select operations on the broadcast socket, waiting
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* for data to become available such that the next read operation will not
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* block. This callback always fails, as the broadcast socket is write-only; it
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* cannot be read.
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*
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* @param socket
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* The broadcast socket to wait for.
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*
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* @param usec_timeout
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* The maximum amount of time to wait for data, in microseconds, or -1 to
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* potentially wait forever.
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*
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* @return
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* A positive value on success, zero if the timeout elapsed and no data is
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* available, or a negative value if an error occurs. This implementation
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* always returns -1, as the broadcast socket is write-only and cannot be
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* read.
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*/
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static int __guac_socket_broadcast_select_handler(guac_socket* socket,
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int usec_timeout) {
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/* Selecting the broadcast socket is not possible */
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return -1;
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}
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/**
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* Frees all implementation-specific data associated with the given socket, but
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* not the socket object itself.
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*
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* @param socket
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* The guac_socket whose associated data should be freed.
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*
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* @return
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* Zero if the data was successfully freed, non-zero otherwise. This
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* implementation always succeeds, and will always return zero.
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*/
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static int __guac_socket_broadcast_free_handler(guac_socket* socket) {
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guac_socket_broadcast_data* data =
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(guac_socket_broadcast_data*) socket->data;
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/* Destroy locks */
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pthread_mutex_destroy(&(data->socket_lock));
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free(data);
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return 0;
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}
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guac_socket* guac_socket_broadcast(guac_client* client) {
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pthread_mutexattr_t lock_attributes;
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/* Allocate socket and associated data */
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guac_socket* socket = guac_socket_alloc();
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guac_socket_broadcast_data* data =
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malloc(sizeof(guac_socket_broadcast_data));
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/* Store client as socket data */
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data->client = client;
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socket->data = data;
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pthread_mutexattr_init(&lock_attributes);
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pthread_mutexattr_setpshared(&lock_attributes, PTHREAD_PROCESS_SHARED);
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/* Init lock */
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pthread_mutex_init(&(data->socket_lock), &lock_attributes);
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/* Set read/write handlers */
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socket->read_handler = __guac_socket_broadcast_read_handler;
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socket->write_handler = __guac_socket_broadcast_write_handler;
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socket->select_handler = __guac_socket_broadcast_select_handler;
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socket->flush_handler = __guac_socket_broadcast_flush_handler;
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socket->lock_handler = __guac_socket_broadcast_lock_handler;
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socket->unlock_handler = __guac_socket_broadcast_unlock_handler;
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socket->free_handler = __guac_socket_broadcast_free_handler;
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return socket;
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}
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