/**
* mds — A micro-display server
* Copyright © 2014 Mattias Andrée (maandree@member.fsf.org)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "sending.h"
#include "globals.h"
#include "client.h"
#include "queued_interception.h"
#include "multicast.h"
#include <libmdsserver/mds-message.h>
#include <libmdsserver/macros.h>
#include <libmdsserver/util.h>
#include <stddef.h>
#include <stdint.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
/**
* Get the client by its socket's file descriptor in a synchronised manner
*
* @param socket_fd The file descriptor of the client's socket
* @return The client
*/
static client_t* client_by_socket(int socket_fd)
{
size_t address;
with_mutex (slave_mutex, address = fd_table_get(&client_map, socket_fd););
return (client_t*)(void*)address;
}
/**
* Send a multicast message to one recipient
*
* @param multicast The message
* @param recipient The recipient
* @param modifying Whether the recipient may modify the message
* @return Evaluates to true if and only if the entire message was sent
*/
static int send_multicast_to_recipient(multicast_t* multicast, client_t* recipient, int modifying)
{
char* msg = multicast->message + multicast->message_ptr;
size_t n = multicast->message_length - multicast->message_ptr;
size_t sent;
/* Skip Modify ID header if the interceptors will not perform a modification. */
if ((modifying == 0) && (multicast->message_ptr == 0))
{
n -= multicast->message_prefix;
multicast->message_ptr += multicast->message_prefix;
}
/* Send the message. */
n *= sizeof(char);
with_mutex (recipient->mutex,
if (recipient->open)
{
sent = send_message(recipient->socket_fd, msg + multicast->message_ptr, n);
n -= sent;
multicast->message_ptr += sent / sizeof(char);
if ((n > 0) && (errno != EINTR))
perror(*argv);
}
);
return n == 0;
}
/**
* Wait for the recipient of a multicast to reply
*
* @param recipient The recipient
* @param modify_id The modify ID of the multicast
*/
static void wait_for_reply(client_t* recipient, uint64_t modify_id)
{
/* pthread_cond_timedwait is required to handle re-exec and termination because
pthread_cond_timedwait and pthread_cond_wait ignore interruptions via signals. */
struct timespec timeout =
{
.tv_sec = 1,
.tv_nsec = 0
};
with_mutex_if (modify_mutex, recipient->modify_message == NULL,
if (hash_table_contains_key(&modify_map, (size_t)modify_id) == 0)
{
hash_table_put(&modify_map, (size_t)modify_id, (size_t)(void*)recipient);
pthread_cond_signal(&slave_cond);
}
);
with_mutex_if (recipient->modify_mutex, recipient->modify_message == NULL,
while ((recipient->modify_message == NULL) && (terminating == 0))
pthread_cond_timedwait(&slave_cond, &slave_mutex, &timeout);
if (terminating == 0)
hash_table_remove(&modify_map, (size_t)modify_id);
);
}
/**
* Multicast a message
*
* @param multicast The multicast message
*/
void multicast_message(multicast_t* multicast)
{
uint64_t modify_id = 0;
size_t n = strlen("Modify ID: ");
if (startswith_n(multicast->message, "Modify ID: ", multicast->message_length, n))
{
char* value = multicast->message + n;
char* lf = strchr(value, '\n');
*lf = '\0';
modify_id = (uint64_t)atoll(value);
*lf = '\n';
}
for (; multicast->interceptions_ptr < multicast->interceptions_count; multicast->interceptions_ptr++)
{
queued_interception_t client_ = multicast->interceptions[multicast->interceptions_ptr];
client_t* client = client_.client;
int modifying = 0;
char* old_buf;
size_t i;
mds_message_t* mod;
/* After unmarshalling at re-exec, client will be NULL and must be mapped from its socket. */
if (client == NULL)
client_.client = client = client_by_socket(client_.socket_fd);
/* Send the message to the recipient. */
if (send_multicast_to_recipient(multicast, client, client_.modifying) == 0)
{
/* Stop if we are re-exec:ing or terminating, or continue to next recipient on error. */
if (terminating)
return;
else
continue;
}
/* Do not wait for a reply if it is non-modifying. */
if (client_.modifying == 0)
{
/* Reset how much of the message has been sent before we continue with next recipient. */
multicast->message_ptr = 0;
continue;
}
/* Wait for a reply. */
wait_for_reply(client, modify_id);
if (terminating)
return;
/* Act upon the reply. */
mod = client->modify_message;
for (i = 0; i < mod->header_count; i++)
if (strequals(mod->headers[i], "Modify: yes"))
{
modifying = 1;
break;
}
if (modifying)
{
n = mod->payload_size;
old_buf = multicast->message;
if (xrealloc(multicast->message, multicast->message_prefix + n, char))
{
perror(*argv);
multicast->message = old_buf;
}
else
memcpy(multicast->message + multicast->message_prefix, mod->payload, n);
}
/* Free the reply. */
mds_message_destroy(client->modify_message);
/* Reset how much of the message has been sent before we continue with next recipient. */
multicast->message_ptr = 0;
}
}
