/**
* 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 "mds-colour.h"
/* TODO reload settings on SIGUSR2 */
/* TODO --save-changes */
#include <libmdsserver/macros.h>
#include <libmdsserver/util.h>
#include <libmdsserver/mds-message.h>
#include <errno.h>
#include <inttypes.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#define reconnect_to_display() -1
#define MDS_COLOUR_VARS_VERSION 0
/**
* This variable should declared by the actual server implementation.
* It must be configured before `main` is invoked.
*
* This tells the server-base how to behave
*/
server_characteristics_t server_characteristics =
{
.require_privileges = 0,
.require_display = 1,
.require_respawn_info = 0,
.sanity_check_argc = 1,
.fork_for_safety = 0,
.danger_is_deadly = 0
};
/**
* Value of the ‘Message ID’ header for the next message
*/
static uint32_t message_id = 1;
/**
* Buffer for received messages
*/
static mds_message_t received;
/**
* Whether the server is connected to the display
*/
static int connected = 1;
/**
* Buffer for sending messages
*/
static char* send_buffer = NULL;
/**
* The size allocated to `send_buffer` divided by `sizeof(char)`
*/
static size_t send_buffer_size = 0;
/**
* Send a full message even if interrupted
*
* @param message:const char* The message to send
* @param length:size_t The length of the message
* @return :int Zero on success, -1 on error
*/
#define full_send(message, length) \
((full_send)(socket_fd, message, length))
/**
* This function will be invoked before `initialise_server` (if not re-exec:ing)
* or before `unmarshal_server` (if re-exec:ing)
*
* @return Non-zero on error
*/
int __attribute__((const)) preinitialise_server(void)
{
return 0;
}
/**
* This function should initialise the server,
* and it not invoked after a re-exec.
*
* @return Non-zero on error
*/
int initialise_server(void)
{
int stage = 0;
const char* const message =
"Command: intercept\n"
"Message ID: 0\n"
"Length: 62\n"
"\n"
"Command: list-colours\n"
"Command: get-colour\n"
"Command: set-colour\n";
fail_if (full_send(message, strlen(message)));
fail_if (server_initialised() < 0); stage++;
fail_if (mds_message_initialise(&received));
return 0;
fail:
xperror(*argv);
if (stage == 1)
mds_message_destroy(&received);
return 1;
}
/**
* This function will be invoked after `initialise_server` (if not re-exec:ing)
* or after `unmarshal_server` (if re-exec:ing)
*
* @return Non-zero on error
*/
int postinitialise_server(void)
{
if (connected)
return 0;
fail_if (reconnect_to_display());
connected = 1;
return 0;
fail:
mds_message_destroy(&received);
return 1;
}
/**
* Calculate the number of bytes that will be stored by `marshal_server`
*
* On failure the program should `abort()` or exit by other means.
* However it should not be possible for this function to fail.
*
* @return The number of bytes that will be stored by `marshal_server`
*/
size_t marshal_server_size(void)
{
return 2 * sizeof(int) + sizeof(uint32_t) + mds_message_marshal_size(&received);
}
/**
* Marshal server implementation specific data into a buffer
*
* @param state_buf The buffer for the marshalled data
* @return Non-zero on error
*/
int marshal_server(char* state_buf)
{
buf_set_next(state_buf, int, MDS_COLOUR_VARS_VERSION);
buf_set_next(state_buf, int, connected);
buf_set_next(state_buf, uint32_t, message_id);
mds_message_marshal(&received, state_buf);
mds_message_destroy(&received);
return 0;
}
/**
* Unmarshal server implementation specific data and update the servers state accordingly
*
* On critical failure the program should `abort()` or exit by other means.
* That is, do not let `reexec_failure_recover` run successfully, if it unrecoverable
* error has occurred or one severe enough that it is better to simply respawn.
*
* @param state_buf The marshalled data that as not been read already
* @return Non-zero on error
*/
int unmarshal_server(char* state_buf)
{
/* buf_get_next(state_buf, int, MDS_COLOUR_VARS_VERSION); */
buf_next(state_buf, int, 1);
buf_get_next(state_buf, int, connected);
buf_get_next(state_buf, uint32_t, message_id);
fail_if (mds_message_unmarshal(&received, state_buf));
return 0;
fail:
xperror(*argv);
mds_message_destroy(&received);
return -1;
}
/**
* Attempt to recover from a re-exec failure that has been
* detected after the server successfully updated it execution image
*
* @return Non-zero on error
*/
int __attribute__((const)) reexec_failure_recover(void)
{
return -1;
}
/**
* Perform the server's mission
*
* @return Non-zero on error
*/
int master_loop(void)
{
int rc = 1, r;
while (!reexecing && !terminating)
{
if (danger)
{
danger = 0;
free(send_buffer), send_buffer = NULL;
send_buffer_size = 0;
}
if (r = mds_message_read(&received, socket_fd), r == 0)
if (r = handle_message(), r == 0)
continue;
if (r == -2)
{
eprint("corrupt message received, aborting.");
goto done;
}
else if (errno == EINTR)
continue;
else
fail_if (errno != ECONNRESET);
eprint("lost connection to server.");
mds_message_destroy(&received);
mds_message_initialise(&received);
connected = 0;
fail_if (reconnect_to_display());
connected = 1;
}
rc = 0;
goto done;
fail:
xperror(*argv);
done:
if (rc || !reexecing)
mds_message_destroy(&received);
free(send_buffer);
return rc;
}
/**
* Handle the received message
*
* @return Zero on success, -1 on error
*/
int handle_message(void)
{
const char* recv_command = NULL;
const char* recv_client_id = "0:0";
const char* recv_message_id = NULL;
const char* recv_include_values = NULL;
const char* recv_name = NULL;
const char* recv_remove = NULL;
const char* recv_bytes = NULL;
const char* recv_red = NULL;
const char* recv_green = NULL;
const char* recv_blue = NULL;
size_t i;
#define __get_header(storage, header) \
(startswith(received.headers[i], header)) \
storage = received.headers[i] + strlen(header)
for (i = 0; i < received.header_count; i++)
{
if __get_header(recv_command, "Command: ");
else if __get_header(recv_client_id, "Client ID: ");
else if __get_header(recv_message_id, "Message ID: ");
else if __get_header(recv_include_values, "Include values: ");
else if __get_header(recv_name, "Name: ");
else if __get_header(recv_remove, "Remove: ");
else if __get_header(recv_bytes, "Bytes: ");
else if __get_header(recv_red, "Red: ");
else if __get_header(recv_green, "Green: ");
else if __get_header(recv_blue, "Blue: ");
}
#undef __get_header
if (recv_message_id == NULL)
{
eprint("received message without ID, ignoring, master server is misbehaving.");
return 0;
}
if (recv_command == NULL)
return 0; /* How did that get here, not matter, just ignore it? */
#define t(expr) do { fail_if (expr); return 0; } while (0)
if (strequals(recv_command, "list-colours"))
t (handle_list_colours(recv_client_id, recv_message_id, recv_include_values));
if (strequals(recv_command, "get-colour"))
t (handle_get_colour(recv_client_id, recv_message_id, recv_name));
if (strequals(recv_command, "set-colour"))
t (handle_set_colour(recv_name, recv_remove, recv_bytes, recv_red, recv_green, recv_blue));
#undef t
return 0; /* How did that get here, not matter, just ignore it? */
fail:
return -1;
}
/**
* Handle the received message after it has been
* identified to contain `Command: list-colours`
*
* @param recv_client_id The value of the `Client ID`-header, "0:0" if omitted
* @param recv_message_id The value of the `Message ID`-header
* @param recv_include_values The value of the `Include values`-header, `NULL` if omitted
* @return Zero on success, -1 on error
*/
int handle_list_colours(const char* recv_client_id, const char* recv_message_id,
const char* recv_include_values)
{
}
/**
* Handle the received message after it has been
* identified to contain `Command: get-colour`
*
* @param recv_client_id The value of the `Client ID`-header, "0:0" if omitted
* @param recv_message_id The value of the `Message ID`-header
* @param recv_name The value of the `Name`-header, `NULL` if omitted
* @return Zero on success, -1 on error
*/
int handle_get_colour(const char* recv_client_id, const char* recv_message_id, const char* recv_name)
{
}
/**
* Handle the received message after it has been
* identified to contain `Command: set-colour`
*
* @param recv_name The value of the `Name`-header, `NULL` if omitted
* @param recv_remove The value of the `Remove`-header, `NULL` if omitted
* @param recv_bytes The value of the `Bytes`-header, `NULL` if omitted
* @param recv_red The value of the `Red`-header, `NULL` if omitted
* @param recv_green The value of the `Green`-header, `NULL` if omitted
* @param recv_blue The value of the `Blue`-header, `NULL` if omitted
* @return Zero on success, -1 on error
*/
int handle_set_colour(const char* recv_name, const char* recv_remove, const char* recv_bytes,
const char* recv_red, const char* recv_green, const char* recv_blue)
{
int remove_colour = 0;
if (recv_remove == NULL) remove_colour = 0;
else if (strequals(recv_remove, "yes")) remove_colour = 1;
else if (strequals(recv_remove, "no")) remove_colour = 0;
else
{
eprint("got an invalid value on the Remove-header, ignoring.");
return 0;
}
return 0;
}
/**
* This function is called when a signal that
* signals that the system to dump state information
* and statistics has been received
*
* @param signo The signal that has been received
*/
void received_info(int signo)
{
(void) signo;
iprintf("next message ID: %" PRIu32, message_id);
iprintf("connected: %s", connected ? "yes" : "no");
iprintf("send buffer size: %zu bytes", send_buffer_size);
}
