/**
* 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 "mds-registry.h"
#include <libmdsserver/macros.h>
#include <libmdsserver/util.h>
#include <libmdsserver/mds-message.h>
#include <libmdsserver/hash-table.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>
#define reconnect_to_display() -1 /* TODO */
#define MDS_REGISTRY_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
};
/**
* Value of the ‘Message ID’ header for the next message
*/
static int32_t message_id = 2;
/**
* Buffer for received messages
*/
static mds_message_t received;
/**
* Whether the server is connected to the display
*/
static int connected = 1;
/**
* Protocol registry table
*/
static hash_table_t reg_table;
/**
* Reusable buffer for data to send
*/
static char* send_buffer = NULL;
/**
* The size of `send_buffer`
*/
static size_t send_buffer_size = 0;
/**
* General mutex
*/
static pthread_mutex_t reg_mutex;
/**
* General condition
*/
static pthread_cond_t reg_cond;
/**
* Used to temporarily store the old value when reallocating heap-allocations
*/
static char* old;
/**
* 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)
{
if ((errno = pthread_mutex_init(®_mutex, NULL)))
{
perror(*argv);
return 1;
}
if ((errno = pthread_cond_init(®_cond, NULL)))
{
perror(*argv);
pthread_mutex_destroy(®_mutex);
return 1;
}
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)
{
const char* const message =
"Command: intercept\n"
"Message ID: 0\n"
"Length: 32\n"
"\n"
"Command: register\n"
"Client closed\n"
/* -- NEXT MESSAGE -- */
"Command: reregister\n"
"Message ID: 1\n"
"\n";
/* We are asking all servers to reregister their
protocols for two reasons:
1) The server would otherwise not get registrations
from servers started before this server.
2) If this server crashes we may miss registrations
that happen between the crash and the recovery.
*/
if (full_send(message, strlen(message)))
return 1;
if (hash_table_create_tuned(®_table, 32))
{
perror(*argv);
hash_table_destroy(®_table, NULL, NULL);
return 1;
}
reg_table.key_comparator = (compare_func*)string_comparator;
reg_table.hasher = (hash_func*)string_hash;
server_initialised();
mds_message_initialise(&received);
return 0;
}
/**
* 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;
if (reconnect_to_display())
{
mds_message_destroy(&received);
return 1;
}
connected = 1;
return 0;
}
/**
* 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)
{
size_t i, rc = 2 * sizeof(int) + sizeof(int32_t) + 3 * sizeof(size_t);
hash_entry_t* entry;
rc += mds_message_marshal_size(&received);
foreach_hash_table_entry (reg_table, i, entry)
{
char* command = (char*)(void*)(entry->key);
size_t len = strlen(command) + 1;
client_list_t* list = (client_list_t*)(void*)(entry->value);
rc += len + sizeof(size_t) + client_list_marshal_size(list);
}
return rc;
}
/**
* 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)
{
size_t i, n = mds_message_marshal_size(&received);
hash_entry_t* entry;
buf_set_next(state_buf, int, MDS_REGISTRY_VARS_VERSION);
buf_set_next(state_buf, int, connected);
buf_set_next(state_buf, int32_t, message_id);
buf_set_next(state_buf, size_t, n);
mds_message_marshal(&received, state_buf);
state_buf += n / sizeof(char);
buf_set_next(state_buf, size_t, reg_table.capacity);
buf_set_next(state_buf, size_t, reg_table.size);
foreach_hash_table_entry (reg_table, i, entry)
{
char* command = (char*)(void*)(entry->key);
size_t len = strlen(command) + 1;
client_list_t* list = (client_list_t*)(void*)(entry->value);
memcpy(state_buf, command, len * sizeof(char));
state_buf += len;
n = client_list_marshal_size(list);
buf_set_next(state_buf, size_t, n);
client_list_marshal(list, state_buf);
state_buf += n / sizeof(char);
}
hash_table_destroy(®_table, (free_func*)reg_table_free_key, (free_func*)reg_table_free_value);
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)
{
char* command;
client_list_t* list;
size_t i, n, m;
int stage = 0;
/* buf_get_next(state_buf, int, MDS_REGISTRY_VARS_VERSION); */
buf_next(state_buf, int, 1);
buf_get_next(state_buf, int, connected);
buf_get_next(state_buf, int32_t, message_id);
buf_get_next(state_buf, size_t, n);
fail_if (mds_message_unmarshal(&received, state_buf));
state_buf += n / sizeof(char);
stage = 1;
buf_get_next(state_buf, size_t, n);
fail_if (hash_table_create_tuned(®_table, n));
buf_get_next(state_buf, size_t, n);
for (i = 0; i < n; i++)
{
stage = 1;
fail_if ((command = strdup(state_buf)) == NULL);
state_buf += strlen(command) + 1;
stage = 2;
fail_if ((list = malloc(sizeof(client_list_t))) == NULL);
buf_get_next(state_buf, size_t, m);
stage = 3;
fail_if (client_list_unmarshal(list, state_buf));
state_buf += m / sizeof(char);
hash_table_put(®_table, (size_t)(void*)command, (size_t)(void*)list);
fail_if (errno);
}
reg_table.key_comparator = (compare_func*)string_comparator;
reg_table.hasher = (hash_func*)string_hash;
return 0;
pfail:
perror(*argv);
mds_message_destroy(&received);
if (stage >= 1)
hash_table_destroy(®_table, (free_func*)reg_table_free_key, (free_func*)reg_table_free_value);
if (stage >= 2)
free(command);
if (stage >= 3)
{
client_list_destroy(list);
free(list);
}
abort();
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;
while (!reexecing && !terminating)
{
int r = mds_message_read(&received, socket_fd);
if (r == 0)
{
r = handle_message();
if (r == 0)
continue;
}
if (r == -2)
{
eprint("corrupt message received, aborting.");
goto fail;
}
else if (errno == EINTR)
continue;
else if (errno != ECONNRESET)
goto pfail;
eprint("lost connection to server.");
mds_message_destroy(&received);
mds_message_initialise(&received);
connected = 0;
if (reconnect_to_display())
goto fail;
connected = 1;
}
rc = 0;
goto fail;
pfail:
perror(*argv);
fail:
if (rc || !reexecing)
{
hash_table_destroy(®_table, (free_func*)reg_table_free_key, (free_func*)reg_table_free_value);
mds_message_destroy(&received);
}
pthread_mutex_destroy(®_mutex);
pthread_cond_destroy(®_cond);
free(send_buffer);
return rc;
}
/**
* 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)
{
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;
if (recv_client_id && recv_message_id && recv_length && recv_action)
break;
}
#undef __get_header
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;
}
if (recv_length != NULL)
length = (size_t)atoll(recv_length);
if (recv_action != NULL)
recv_action = "add";
#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 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. */
size_t i, j, ptr = 0, size = 1;
size_t* keys = NULL;
size_t* old_keys;
fail_if ((errno = pthread_mutex_lock(®_mutex)));
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)
{
client_list_t* list = (client_list_t*)(void*)(entry->value);
client_list_remove(list, client);
if (list->size)
continue;
fail_if ((keys == NULL) && xmalloc(keys, size, size_t));
if (ptr == size ? growalloc(old_keys, keys, size, size_t) : 0)
goto fail;
keys[ptr++] = entry->key;
}
}
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);
}
pthread_mutex_unlock(®_mutex);
free(keys);
return 0;
pfail:
perror(*argv);
fail:
free(keys);
return -1;
}
/**
* 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"))
return handle_register_message();
return handle_close_message();
}
/**
* Convert a client ID string into a client ID integer
*
* @param str The client ID string
* @return The client ID integer
*/
uint64_t parse_client_id(const char* str)
{
char client_words[22];
char* client_high;
char* client_low;
uint64_t client;
strcpy(client_high = client_words, str);
client_low = rawmemchr(client_words, ':');
*client_low++ = '\0';
client = (uint64_t)atoll(client_high);
client <<= 32;
client |= (uint64_t)atoll(client_low);
return client;
}
/**
* 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)
{
if (has_key)
{
size_t address = hash_table_get(®_table, command_key);
client_list_t* list = (client_list_t*)(void*)address;
if (client_list_add(list, client) < 0)
goto pfail;
}
else
{
client_list_t* list = malloc(sizeof(client_list_t));
void* address = list;
if (list == NULL)
goto pfail;
if ((command = strdup(command)) == NULL)
{
free(list);
goto pfail;
}
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))
{
client_list_destroy(list);
free(list);
free(command);
goto pfail;
}
}
return 0;
pfail:
perror(*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;
client_list_remove(list, client);
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);
if (action == 1)
{
if (registry_action_add(has_key, command, command_key, client))
return -1;
}
else if ((action == -1) && has_key)
registry_action_remove(command_key, client);
else if ((action == 0) && !has_key)
{
if ((command = strdup(command)) == NULL)
goto pfail_wait;
command_key = (size_t)(void*)command;
if (hash_table_put(wait_set, command_key, 1) == 0)
if (errno)
{
free(command);
goto pfail_wait;
}
}
return 0;
pfail_wait:
perror(*argv);
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
*/
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;
if (action == 0)
{
wait_set = malloc(sizeof(hash_table_t));
if (hash_table_create(wait_set))
{
hash_table_destroy(wait_set, NULL, NULL);
free(wait_set);
goto pfail;
}
wait_set->key_comparator = (compare_func*)string_comparator;
wait_set->hasher = (hash_func*)string_hash;
}
if (received.payload_size == length)
{
if (growalloc(old, received.payload, received.payload_size, char))
{
if (wait_set != NULL)
hash_table_destroy(wait_set, NULL, NULL), free(wait_set);
return -1;
}
else
payload = received.payload;
}
payload[length] = '\n';
fail_if ((errno = pthread_mutex_lock(®_mutex)));
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 (registry_action_act(command, action, client, wait_set))
goto fail_in_mutex;
}
pthread_mutex_unlock(®_mutex);
if (action == 0)
{
/* FIXME */
}
return 0;
pfail:
perror(*argv);
return -1;
fail_in_mutex:
pthread_mutex_unlock(®_mutex);
return -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
*/
int list_registry(const char* recv_client_id, const char* recv_message_id)
{
size_t ptr = 0, i;
hash_entry_t* entry;
if (send_buffer_size == 0)
{
fail_if (xmalloc(send_buffer, 256, char));
send_buffer_size = 256;
}
fail_if ((errno = pthread_mutex_lock(®_mutex)));
foreach_hash_table_entry (reg_table, i, entry)
{
size_t key = entry->key;
char* command = (char*)(void*)key;
size_t len = strlen(command);
while (ptr + len + 1 >= send_buffer_size)
if (growalloc(old, send_buffer, send_buffer_size, char))
goto fail_in_mutex;
memcpy(send_buffer + ptr, command, len * sizeof(char));
ptr += len;
send_buffer[ptr++] = '\n';
}
i = strlen(recv_message_id) + strlen(recv_client_id) + 10 + 19;
i += strlen("To: %s\nIn response to: %s\nMessage ID: %" PRIi32 "\nLength: %" PRIu64 "\n\n");
while (ptr + i >= send_buffer_size)
{
if (growalloc(old, send_buffer, send_buffer_size, char))
goto fail_in_mutex;
}
sprintf(send_buffer + ptr, "To: %s\nIn response to: %s\nMessage ID: %" PRIi32 "\nLength: %" PRIu64 "\n\n",
recv_message_id, recv_client_id, message_id, ptr);
message_id = message_id == INT32_MAX ? 0 : (message_id + 1);
pthread_mutex_unlock(®_mutex);
if (full_send(send_buffer + ptr, strlen(send_buffer + ptr)))
return 1;
return full_send(send_buffer, ptr);
fail_in_mutex:
pthread_mutex_unlock(®_mutex);
return -1;
pfail:
perror(*argv);
return -1;
}
/**
* Free a key from a table
*
* @param obj The key
*/
void reg_table_free_key(size_t obj)
{
char* command = (char*)(void*)obj;
free(command);
}
/**
* Free a value from a table
*
* @param obj The value
*/
void reg_table_free_value(size_t obj)
{
client_list_t* list = (client_list_t*)(void*)obj;
client_list_destroy(list);
free(list);
}
/**
* Send a full message even if interrupted
*
* @param message The message to send
* @param length The length of the message
* @return Non-zero on success
*/
int full_send(const char* message, size_t length)
{
size_t sent;
while (length > 0)
{
sent = send_message(socket_fd, message, length);
if (sent > length)
{
eprint("Sent more of a message than exists in the message, aborting.");
return -1;
}
else if ((sent < length) && (errno != EINTR))
{
perror(*argv);
return -1;
}
message += sent;
length -= sent;
}
return 0;
}
