/**
* mds — A micro-display server
* Copyright © 2014, 2015 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 "receiving.h"
#include "globals.h"
#include "client.h"
#include "interceptors.h"
#include <libmdsserver/hash-table.h>
#include <libmdsserver/mds-message.h>
#include <libmdsserver/macros.h>
#include <stddef.h>
#include <inttypes.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
/**
* Queue a message for multicasting
*
* @param message The message
* @param length The length of the message
* @param sender The original sender of the message
*/
void queue_message_multicast(char* message, size_t length, client_t* sender);
/**
* Notify waiting client about a received message modification
*
* @param client The client whom sent the message
* @param message The message
* @param modify_id The modify ID of the message
* @return Normally zero, but 1 if exited because of re-exec or termination
*/
static int modifying_notify(client_t* client, mds_message_t message, 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
};
size_t address;
client_t* recipient;
mds_message_t* multicast;
size_t i;
pthread_mutex_lock(&(modify_mutex));
while (hash_table_contains_key(&modify_map, (size_t)modify_id) == 0)
{
if (terminating)
{
pthread_mutex_unlock(&(modify_mutex));
return 1;
}
pthread_cond_timedwait(&slave_cond, &slave_mutex, &timeout);
}
address = hash_table_get(&modify_map, (size_t)modify_id);
recipient = (client_t*)(void*)address;
fail_if (xmalloc(multicast = recipient->modify_message, 1, mds_message_t));
mds_message_zero_initialise(multicast);
fail_if (xmemdup(multicast->payload, message.payload, message.payload_size, char));
fail_if (xmalloc(multicast->headers, message.header_count, char*));
for (i = 0; i < message.header_count; i++, multicast->header_count++)
fail_if (xstrdup(multicast->headers[i], message.headers[i]));
done:
pthread_mutex_unlock(&(modify_mutex));
with_mutex (client->modify_mutex, pthread_cond_signal(&(client->modify_cond)););
return 0;
fail:
xperror(*argv);
if (multicast != NULL)
{
mds_message_destroy(multicast);
free(multicast);
recipient->modify_message = NULL;
}
goto done;
}
/**
* Add intercept conditions listed in the payload of a message
*
* @param client The intercepting client
* @param modifying Whether then client may modify the messages
* @param priority The client's interception priority
* @param stop Whether to stop listening rather than start or reconfigure
* @return Zero on success, -1 on error
*/
static int add_intercept_conditions_from_message(client_t* client, int modifying, int64_t priority, int stop)
{
int saved_errno;
char* payload = client->message.payload;
size_t payload_size = client->message.payload_size;
size_t size = 64;
char* buf;
fail_if (xmalloc(buf, size + 1, char));
/* All messages */
if (client->message.payload_size == 0)
{
*buf = '\0';
add_intercept_condition(client, buf, priority, modifying, stop);
goto done;
}
/* Filtered messages */
for (;;)
{
char* end = memchr(payload, '\n', payload_size);
size_t len = end == NULL ? payload_size : (size_t)(end - payload);
if (len == 0)
{
payload++;
payload_size--;
break;
}
if (len > size)
{
char* old_buf = buf;
if (xrealloc(buf, (size <<= 1) + 1, char))
{
saved_errno = errno;
free(old_buf);
pthread_mutex_unlock(&(client->mutex));
fail_if (errno = saved_errno, 1);
}
}
memcpy(buf, payload, len);
buf[len] = '\0';
add_intercept_condition(client, buf, priority, modifying, stop);
if (end == NULL)
break;
payload = end + 1;
payload_size -= len + 1;
}
done:
free(buf);
return 0;
fail:
return -1;
}
/**
* Assign and ID to a client, if not already assigned, and send it to that client
*
* @param client The client to who an ID should be assigned
* @param message_id The message ID of the ID request
* @return Zero on success, -1 on error
*/
static int assign_and_send_id(client_t* client, const char* message_id)
{
char* msgbuf = NULL;
char* msgbuf_;
size_t n;
int rc = -1;
/* Construct response. */
n = 2 * 10 + strlen(message_id) + 1;
n += strlen("ID assignment: :\nIn response to: \n\n");
fail_if (xmalloc(msgbuf, n, char));
snprintf(msgbuf, n,
"ID assignment: %" PRIu32 ":%" PRIu32 "\n"
"In response to: %s\n"
"\n",
(uint32_t)(client->id >> 32),
(uint32_t)(client->id >> 0),
message_id == NULL ? "" : message_id);
n = strlen(msgbuf);
/* Multicast the reply. */
fail_if (xstrdup(msgbuf_, msgbuf));
queue_message_multicast(msgbuf_, n, client);
/* Queue message to be sent when this function returns.
This done to simplify `multicast_message` for re-exec and termination. */
#define fail fail_in_mutex
with_mutex (client->mutex,
if (client->send_pending_size == 0)
{
/* Set the pending message. */
client->send_pending = msgbuf;
client->send_pending_size = n;
}
else
{
/* Concatenate message to already pending messages. */
size_t new_len = client->send_pending_size + n;
char* msg_new = client->send_pending;
fail_if (xrealloc(msg_new, new_len, char));
memcpy(msg_new + client->send_pending_size, msgbuf, n * sizeof(char));
client->send_pending = msg_new;
client->send_pending_size = new_len;
}
(msgbuf = NULL, rc = 0, errno = 0);
fail_in_mutex:
);
#undef fail
fail: /* Also success. */
xperror(*argv);
free(msgbuf);
return rc;
}
/**
* Perform actions that should be taken when
* a message has been received from a client
*
* @param client The client whom sent the message
* @return Normally zero, but 1 if exited because of re-exec or termination
*/
int message_received(client_t* client)
{
mds_message_t message = client->message;
int assign_id = 0;
int modifying = 0;
int intercept = 0;
int64_t priority = 0;
int stop = 0;
const char* message_id = NULL;
uint64_t modify_id = 0;
char* msgbuf = NULL;
size_t i, n;
/* Parser headers. */
for (i = 0; i < message.header_count; i++)
{
const char* h = message.headers[i];
if (strequals(h, "Command: assign-id")) assign_id = 1;
else if (strequals(h, "Command: intercept")) intercept = 1;
else if (strequals(h, "Modifying: yes")) modifying = 1;
else if (strequals(h, "Stop: yes")) stop = 1;
else if (startswith(h, "Message ID: ")) message_id = strstr(h, ": ") + 2;
else if (startswith(h, "Priority: ")) priority = ato64(strstr(h, ": ") + 2);
else if (startswith(h, "Modify ID: ")) modify_id = atou64(strstr(h, ": ") + 2);
}
/* Notify waiting client about a received message modification. */
if (modifying)
return modifying_notify(client, message, modify_id);
/* Do nothing more, not not even multicast this message. */
if (message_id == NULL)
{
eprint("received message without a message ID, ignoring.");
return 0;
}
/* Assign ID if not already assigned. */
if (assign_id && (client->id == 0))
{
intercept |= 2;
with_mutex_if (slave_mutex, (client->id = next_client_id++) == 0,
eprint("this is impossible, ID counter has overflowed.");
/* If the program ran for a millennium it would
take c:a 585 assignments per nanosecond. This
cannot possibly happen. (It would require serious
dedication by generations of ponies (or just an alicorn)
to maintain the process and transfer it new hardware.) */
abort();
);
}
/* Make the client listen for messages addressed to it. */
if (intercept)
{
pthread_mutex_lock(&(client->mutex));
if ((intercept & 1)) /* from payload */
fail_if (add_intercept_conditions_from_message(client, modifying, priority, stop) < 0);
if ((intercept & 2)) /* "To: $(client->id)" */
{
char buf[26];
xsnprintf(buf, "To: %" PRIu32 ":%" PRIu32,
(uint32_t)(client->id >> 32),
(uint32_t)(client->id >> 0));
add_intercept_condition(client, buf, priority, modifying, 0);
}
pthread_mutex_unlock(&(client->mutex));
}
/* Multicast the message. */
n = mds_message_compose_size(&message);
fail_if (xbmalloc(msgbuf, n));
mds_message_compose(&message, msgbuf);
queue_message_multicast(msgbuf, n / sizeof(char), client);
msgbuf = NULL;
/* Send asigned ID. */
if (assign_id)
fail_if (assign_and_send_id(client, message_id) < 0);
return 0;
fail:
xperror(*argv);
free(msgbuf);
return 0;
}
