/**
* 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 "registry.h"
#include "util.h"
#include "globals.h"
#include "slave.h"
#include "../mds-base.h"
#include <libmdsserver/util.h>
#include <libmdsserver/macros.h>
#include <libmdsserver/hash-help.h>
#include <libmdsserver/client-list.h>
#include <errno.h>
#include <inttypes.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
/**
* Handle the received message containing a ‘Client closed’-header
*
* @return Zero on success -1 on error or interruption,
* `errno` will be set accordingly
*/
static int handle_close_message(void)
{
/* Servers do not close too often, there is no need to
optimise this with another hash table. Doing so would
also require some caution because the keys are 32-bit
on 32-bit computers, and the client ID:s are 64-bit. */
size_t i, j, ptr = 0, size = 1;
size_t* keys = NULL;
size_t* old_keys;
/* Remove server for all protocols. */
for (i = 0; i < received.header_count; i++)
if (startswith(received.headers[i], "Client closed: "))
{
uint64_t client = parse_client_id(received.headers[i] + strlen("Client closed: "));
hash_entry_t* entry;
foreach_hash_table_entry (reg_table, j, entry)
{
/* Remove server from list of servers that support the protocol,
once, if it is in the list. */
client_list_t* list = (client_list_t*)(void*)(entry->value);
client_list_remove(list, client);
if (list->size)
continue;
/* If no servers support the protocol, list the protocol for removal. */
fail_if ((keys == NULL) && xmalloc(keys, size, size_t));
fail_if (ptr == size ? growalloc(old_keys, keys, size, size_t) : 0);
keys[ptr++] = entry->key;
}
/* Mark client as closed. */
close_slaves(client);
}
/* Close slaves those clients have closed. */
with_mutex (slave_mutex, pthread_cond_broadcast(&slave_cond););
/* Remove protocol that no longer have any supporting servers. */
for (i = 0; i < ptr; i++)
{
hash_entry_t* entry = hash_table_get_entry(®_table, keys[i]);
client_list_t* list = (client_list_t*)(void*)(entry->value);
char* command = (char*)(void*)(entry->key);
hash_table_remove(®_table, entry->key);
client_list_destroy(list);
free(list);
free(command);
}
free(keys);
return 0;
fail:
xperror(*argv);
free(keys);
return -1;
}
/**
* Add a protocol to the registry
*
* @param has_key Whether the command is already in the registry
* @param command The command
* @param command_key The address of `command`
* @param client The ID of the client that implements the server-side of the protocol
* @return Non-zero on error
*/
static int registry_action_add(int has_key, char* command, size_t command_key, uint64_t client)
{
int saved_errno;
if (has_key)
{
/* Add server to protocol if the protocol is already in the table. */
size_t address = hash_table_get(®_table, command_key);
client_list_t* list = (client_list_t*)(void*)address;
fail_if (client_list_add(list, client) < 0);
}
else
{
/* If the protocol is not already in the table. */
/* Allocate list of servers for the protocol. */
client_list_t* list;
void* address;
fail_if (xmalloc(address = list, 1, client_list_t));
/* Duplicate the protocol name so it can be accessed later. */
if (xstrdup(command, command))
{
saved_errno = errno, free(list), errno = saved_errno;
fail_if (1);
}
/* Create list of servers, add server to list and add the protocol to the table. */
command_key = (size_t)(void*)command;
if (client_list_create(list, 1) ||
client_list_add(list, client) ||
(hash_table_put(®_table, command_key, (size_t)address) == 0))
{
saved_errno = errno;
client_list_destroy(list);
free(list);
free(command);
errno = saved_errno;
fail_if (1);
}
}
/* Notify slaves. */
fail_if (advance_slaves(command));
return 0;
fail:
xperror(*argv);
return -1;
}
/**
* Remove a protocol from the registry
*
* @param command_key The address of a string that contains the command
* @param client The ID of the client that implements the server-side of the protocol
* @return Non-zero on error
*/
static void registry_action_remove(size_t command_key, uint64_t client)
{
hash_entry_t* entry = hash_table_get_entry(®_table, command_key);
size_t address = entry->value;
client_list_t* list = (client_list_t*)(void*)address;
/* Remove server from protocol. */
client_list_remove(list, client);
/* Remove protocol if no servers support it anymore. */
if (list->size == 0)
{
client_list_destroy(list);
free(list);
hash_table_remove(®_table, command_key);
reg_table_free_key(entry->key);
}
}
/**
* Modify the protocol registry or list missing protocols
*
* @param command The command
* @param action -1 to remove command, +1 to add commands, 0 to
* wait until the message commnds are registered
* @param client The ID of the client that implements the server-side of the protocol
* @param wait_set Table to fill with missing protocols if `action == 0`
* @return Non-zero on error
*/
static int registry_action_act(char* command, int action, uint64_t client, hash_table_t* wait_set)
{
size_t command_key = (size_t)(void*)command;
int has_key = hash_table_contains_key(®_table, command_key);
int saved_errno;
if (action == 1)
{
/* Register server to protocol. */
fail_if (registry_action_add(has_key, command, command_key, client));
}
else if ((action == -1) && has_key)
/* Unregister server from protocol. */
registry_action_remove(command_key, client);
else if ((action == 0) && !has_key)
{
/* Add protocol to wait set of not present in the protocol table. */
fail_if (xstrdup(command, command));
command_key = (size_t)(void*)command;
if (hash_table_put(wait_set, command_key, 1) == 0)
if (errno)
{
saved_errno = errno, free(command), errno = saved_errno;
fail_if (1);
}
}
return 0;
fail:
xperror(*argv);
if (action != 1)
hash_table_destroy(wait_set, (free_func*)reg_table_free_key, NULL), free(wait_set);
return -1;
}
/**
* Perform an action over the registry
*
* @param length The length of the received message
* @param action -1 to remove command, +1 to add commands, 0 to
* wait until the message commnds are registered
* @param recv_client_id The ID of the client
* @param recv_message_id The ID of the received message
* @return Zero on success -1 on error or interruption,
* `errno` will be set accordingly
*/
static int registry_action(size_t length, int action, const char* recv_client_id, const char* recv_message_id)
{
char* payload = received.payload;
uint64_t client = action ? parse_client_id(recv_client_id) : 0;
hash_table_t* wait_set = NULL;
size_t begin;
int saved_errno;
/* If ‘Action: wait’, create a set for the protocols that are not already available. */
if (action == 0)
{
fail_if (xmalloc(wait_set, 1, hash_table_t));
fail_if (hash_table_create(wait_set));
wait_set->key_comparator = (compare_func*)string_comparator;
wait_set->hasher = (hash_func*)string_hash;
}
/* If the payload buffer is full, increase it so we can fit another character. */
if (received.payload_size == length)
{
fail_if (growalloc(old, received.payload, received.payload_size, char));
payload = received.payload;
}
/* LF-terminate the payload, perhaps it did not have a terminal LF. */
payload[length] = '\n';
/* For all protocols in the payload, either add or remove
them from or to the protocl table or the wait set. */
for (begin = 0; begin < length;)
{
char* end = rawmemchr(payload + begin, '\n');
size_t len = (size_t)(end - payload) - begin - 1;
char* command = payload + begin;
command[len] = '\0';
begin += len + 1;
if (len > 0)
if (registry_action_act(command, action, client, wait_set))
fail_if (wait_set = NULL, 1);
}
/* If ‘Action: wait’, start a new thread that waits for the protocols and the responds. */
if (action == 0)
if (start_slave(wait_set, recv_client_id, recv_message_id))
fail_if (wait_set = NULL, 1);
return 0;
fail:
saved_errno = errno;
if (wait_set != NULL)
hash_table_destroy(wait_set, NULL, NULL), free(wait_set);
return errno = saved_errno, -1;
}
/**
* Send a list of all registered commands to a client
*
* @param recv_client_id The ID of the client
* @param recv_message_id The ID of the received message
* @return Zero on success, -1 on error or interruption,
* `errno` will be set accordingly
*/
static int list_registry(const char* recv_client_id, const char* recv_message_id)
{
size_t ptr = 0, i;
hash_entry_t* entry;
/* Allocate the send buffer for the first time, it cannot be doubled if it is zero. */
if (send_buffer_size == 0)
{
fail_if (xmalloc(send_buffer, 256, char));
send_buffer_size = 256;
}
/* Add all protocols to the send buffer. */
foreach_hash_table_entry (reg_table, i, entry)
{
size_t key = entry->key;
char* command = (char*)(void*)key;
size_t len = strlen(command);
/* Make sure the send buffer can fit all protocols. */
while (ptr + len + 1 >= send_buffer_size)
fail_if (growalloc(old, send_buffer, send_buffer_size, char));
memcpy(send_buffer + ptr, command, len * sizeof(char));
ptr += len;
send_buffer[ptr++] = '\n';
}
/* Make sure the message headers can fit the send buffer. */
i = strlen(recv_message_id) + strlen(recv_client_id) + 10 + 19;
i += strlen("To: %s\nIn response to: %s\nMessage ID: %" PRIu32 "\nLength: %" PRIu64 "\n\n");
while (ptr + i >= send_buffer_size)
fail_if (growalloc(old, send_buffer, send_buffer_size, char));
/* Construct message headers. */
sprintf(send_buffer + ptr, "To: %s\nIn response to: %s\nMessage ID: %" PRIu32 "\nLength: %" PRIu64 "\n\n",
recv_client_id, recv_message_id, message_id, ptr);
/* Increase message ID. */
with_mutex (slave_mutex, message_id = message_id == UINT32_MAX ? 0 : (message_id + 1););
/* Send message. */
fail_if (full_send(send_buffer + ptr, strlen(send_buffer + ptr)));
fail_if (full_send(send_buffer, ptr));
return 0;
fail:
return -1;
}
/**
* Handle the received message containing ‘Command: register’-header–value
*
* @return Zero on success -1 on error or interruption,
* `errno` will be set accordingly
*/
static int handle_register_message(void)
{
/* Fetch message headers. */
const char* recv_client_id = NULL;
const char* recv_message_id = NULL;
const char* recv_length = NULL;
const char* recv_action = NULL;
size_t i, length = 0;
#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_client_id, "Client ID: ");
else if __get_header(recv_message_id, "Message ID: ");
else if __get_header(recv_length, "Length: ");
else if __get_header(recv_action, "Action: ");
else
continue;
/* Stop if we got all headers we recognised, except ‘Time to live’. */
if (recv_client_id && recv_message_id && recv_length && recv_action)
break;
}
#undef __get_header
/* Validate headers. */
if ((recv_client_id == NULL) || (strequals(recv_client_id, "0:0")))
{
eprint("received message from anonymous sender, ignoring.");
return 0;
}
else if (strchr(recv_client_id, ':') == NULL)
{
eprint("received message from sender without a colon it its ID, ignoring, invalid ID.");
return 0;
}
else if ((recv_length == NULL) && ((recv_action == NULL) || !strequals(recv_action, "list")))
{
eprint("received empty message without `Action: list`, ignoring, has no effect.");
return 0;
}
else if (recv_message_id == NULL)
{
eprint("received message with ID, ignoring, master server is misbehaving.");
return 0;
}
/* Get message length, and make sure the action is defined. */
if (recv_length != NULL)
length = atoz(recv_length);
if (recv_action != NULL)
recv_action = "add";
/* Perform action. */
#define __registry_action(action) registry_action(length, action, recv_client_id, recv_message_id)
if (strequals(recv_action, "add")) return __registry_action(1);
else if (strequals(recv_action, "remove")) return __registry_action(-1);
else if (strequals(recv_action, "wait")) return __registry_action(0);
else if (strequals(recv_action, "list")) return list_registry(recv_client_id, recv_message_id);
else
{
eprint("received invalid action, ignoring.");
return 0;
}
#undef __registry_action
}
/**
* Handle the received message
*
* @return Zero on success, -1 on error or interruption,
* `errno` will be set accordingly
*/
int handle_message(void)
{
size_t i;
for (i = 0; i < received.header_count; i++)
if (strequals(received.headers[i], "Command: register"))
{
fail_if (handle_register_message());
return 0;
}
fail_if (handle_close_message());
return 0;
fail:
return -1;
}
