/**
* mds — A micro-display server
* Copyright © 2014, 2015, 2016, 2017 Mattias Andrée (maandree@kth.se)
*
* 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>
/**
* 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))
/**
* 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;
uint64_t client;
hash_entry_t *entry;
client_list_t *list;
char *command;
/* Remove server for all protocols. */
for (i = 0; i < received.header_count; i++) {
if (startswith(received.headers[i], "Client closed: ")) {
client = parse_client_id(received.headers[i] + strlen("Client closed: "));
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. */
list = (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 && 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++) {
entry = hash_table_get_entry(®_table, keys[i]);
list = (void *)(entry->value);
command = (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 __attribute__((nonnull))
registry_action_add(int has_key, char *command, size_t command_key, uint64_t client)
{
int saved_errno;
client_list_t *list;
size_t address;
void *paddress;
if (has_key) {
/* Add server to protocol if the protocol is already in the table. */
address = hash_table_get(®_table, command_key);
list = (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. */
fail_if (xmalloc(paddress = list, 1, client_list_t));
/* Duplicate the protocol name so it can be accessed later. */
if (xstrdup_nn(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)paddress)) {
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 = (void *)address;
/* Remove server from protocol. */
client_list_remove(list, client);
/* Remove protocol if no servers support it anymore. */
if (!list->size) {
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 __attribute__((nonnull))
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;
switch (action) {
case 1:
/* Register server to protocol. */
fail_if (registry_action_add(has_key, command, command_key, client));
break;
case -1:
if (has_key)
/* Unregister server from protocol. */
registry_action_remove(command_key, client);
break;
case 0:
if (has_key)
break;
/* Add protocol to wait set of not present in the protocol table. */
fail_if (xstrdup_nn(command, command));
command_key = (size_t)(void*)command;
if (!hash_table_put(wait_set, command_key, 1) && errno) {
saved_errno = errno, free(command), errno = saved_errno;
fail_if (1);
}
break;
default:
break;
}
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 __attribute__((nonnull))
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, len;
int saved_errno;
char *end, *command;
/* If ‘Action: wait’, create a set for the protocols that are not already available. */
if (!action) {
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;) {
end = rawmemchr(payload + begin, '\n');
len = (size_t)(end - payload) - begin - 1;
command = payload + begin;
command[len] = '\0';
begin += len + 1;
if (len > 0 && 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 && 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)
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 __attribute__((nonnull))
list_registry(const char *recv_client_id, const char *recv_message_id)
{
size_t ptr = 0, i, key, len;
hash_entry_t *entry;
char *command;
/* Allocate the send buffer for the first time, it cannot be doubled if it is zero. */
if (!send_buffer_size) {
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) {
key = entry->key;
command = (char*)(void*)key;
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 = sizeof("To: \n"
"In response to: \n"
"Message ID: \n"
"Origin command: register\n"
"Length: \n"
"\n") / sizeof(char) - 1;
i += strlen(recv_message_id) + strlen(recv_client_id) + 10 + 19;
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\n"
"In response to: %s\n"
"Message ID: %" PRIu32 "\n"
"Origin command: register\n"
"Length: %" 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 || strequals(recv_client_id, "0:0"))
return eprint("received message from anonymous sender, ignoring."), 0;
else if (!strchr(recv_client_id, ':'))
return eprint("received message from sender without a colon it its ID, ignoring, invalid ID."), 0;
else if (!recv_length && (!recv_action || !strequals(recv_action, "list")))
return eprint("received empty message without `Action: list`, ignoring, has no effect."), 0;
else if (!recv_message_id)
return eprint("received message without ID, ignoring, master server is misbehaving."), 0;
/* Get message length, and make sure the action is defined. */
if (recv_length)
length = atoz(recv_length);
if (recv_action)
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;
}
