mosquitto.c

/*
Copyright (c) 2009-2020 Roger Light <roger@atchoo.org>

All rights reserved. This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
and Eclipse Distribution License v1.0 which accompany this distribution.

The Eclipse Public License is available at
   https://www.eclipse.org/legal/epl-2.0/
and the Eclipse Distribution License is available at
  http:https://www.eclipse.org/org/documents/edl-v10.php.

SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause

Contributors:
   Roger Light - initial implementation and documentation.
*/

#include "config.h"

#ifndef WIN32
/* For initgroups() */
#  include <unistd.h>
#  include <grp.h>
#  include <assert.h>
#endif

#ifndef WIN32
#include <pwd.h>
#else
#include <process.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#endif

#ifndef WIN32
#  include <sys/time.h>
#endif

#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#ifdef WITH_SYSTEMD
#  include <systemd/sd-daemon.h>
#endif
#ifdef WITH_WRAP
#include <tcpd.h>
#endif
#ifdef WITH_WEBSOCKETS
#  include <libwebsockets.h>
#endif

#include "mosquitto_broker_internal.h"
#include "memory_mosq.h"
#include "misc_mosq.h"
#include "util_mosq.h"

struct mosquitto_db db;

static struct mosquitto__listener_sock *listensock = NULL;
static int listensock_count = 0;
static int listensock_index = 0;

bool flag_reload = false;
#ifdef WITH_PERSISTENCE
bool flag_db_backup = false;
#endif
bool flag_tree_print = false;
int run;
#ifdef WITH_WRAP
#include <syslog.h>
int allow_severity = LOG_INFO;
int deny_severity = LOG_INFO;
#endif

/* mosquitto shouldn't run as root.
 * This function will attempt to change to an unprivileged user and group if
 * running as root. The user is given in config->user.
 * Returns 1 on failure (unknown user, setuid/setgid failure)
 * Returns 0 on success.
 * Note that setting config->user to "root" does not produce an error, but it
 * strongly discouraged.
 */
int drop_privileges(struct mosquitto__config *config)
{
#if !defined(__CYGWIN__) && !defined(WIN32)
	struct passwd *pwd;
	char *err;
	int rc;

	const char *snap = getenv("SNAP_NAME");
	if(snap && !strcmp(snap, "mosquitto")){
		/* Don't attempt to drop privileges if running as a snap */
		return MOSQ_ERR_SUCCESS;
	}

	if(geteuid() == 0){
		if(config->user && strcmp(config->user, "root")){
			pwd = getpwnam(config->user);
			if(!pwd){
				if(strcmp(config->user, "mosquitto")){
					log__printf(NULL, MOSQ_LOG_ERR, "Error: Unable to drop privileges to '%s' because this user does not exist.", config->user);
					return 1;
				}else{
					log__printf(NULL, MOSQ_LOG_ERR, "Warning: Unable to drop privileges to '%s' because this user does not exist. Trying 'nobody' instead.", config->user);
					pwd = getpwnam("nobody");
					if(!pwd){
						log__printf(NULL, MOSQ_LOG_ERR, "Error: Unable to drop privileges to 'nobody'.");
						return 1;
					}
				}
			}
			if(initgroups(config->user, pwd->pw_gid) == -1){
				err = strerror(errno);
				log__printf(NULL, MOSQ_LOG_ERR, "Error setting groups whilst dropping privileges: %s.", err);
				return 1;
			}
			rc = setgid(pwd->pw_gid);
			if(rc == -1){
				err = strerror(errno);
				log__printf(NULL, MOSQ_LOG_ERR, "Error setting gid whilst dropping privileges: %s.", err);
				return 1;
			}
			rc = setuid(pwd->pw_uid);
			if(rc == -1){
				err = strerror(errno);
				log__printf(NULL, MOSQ_LOG_ERR, "Error setting uid whilst dropping privileges: %s.", err);
				return 1;
			}
		}
		if(geteuid() == 0 || getegid() == 0){
			log__printf(NULL, MOSQ_LOG_WARNING, "Warning: Mosquitto should not be run as root/administrator.");
		}
	}
#else
	UNUSED(config);
#endif
	return MOSQ_ERR_SUCCESS;
}

static void mosquitto__daemonise(void)
{
#ifndef WIN32
	char *err;
	pid_t pid;

	pid = fork();
	if(pid < 0){
		err = strerror(errno);
		log__printf(NULL, MOSQ_LOG_ERR, "Error in fork: %s", err);
		exit(1);
	}
	if(pid > 0){
		exit(0);
	}
	if(setsid() < 0){
		err = strerror(errno);
		log__printf(NULL, MOSQ_LOG_ERR, "Error in setsid: %s", err);
		exit(1);
	}

	assert(freopen("/dev/null", "r", stdin));
	assert(freopen("/dev/null", "w", stdout));
	assert(freopen("/dev/null", "w", stderr));
#else
	log__printf(NULL, MOSQ_LOG_WARNING, "Warning: Can't start in daemon mode in Windows.");
#endif
}


void listener__set_defaults(struct mosquitto__listener *listener)
{
	listener->security_options.allow_anonymous = -1;
	listener->security_options.allow_zero_length_clientid = true;
	listener->protocol = mp_mqtt;
	listener->max_connections = -1;
	listener->max_qos = 2;
	listener->max_topic_alias = 10;
}


void listeners__reload_all_certificates(void)
{
#ifdef WITH_TLS
	int i;
	int rc;
	struct mosquitto__listener *listener;

	for(i=0; i<db.config->listener_count; i++){
		listener = &db.config->listeners[i];
		if(listener->ssl_ctx && listener->certfile && listener->keyfile){
			rc = net__load_certificates(listener);
			if(rc){
				log__printf(NULL, MOSQ_LOG_ERR, "Error when reloading certificate '%s' or key '%s'.",
						listener->certfile, listener->keyfile);
			}
		}
	}
#endif
}


static int listeners__start_single_mqtt(struct mosquitto__listener *listener)
{
	int i;
	struct mosquitto__listener_sock *listensock_new;

	if(net__socket_listen(listener)){
		return 1;
	}
	listensock_count += listener->sock_count;
	listensock_new = mosquitto__realloc(listensock, sizeof(struct mosquitto__listener_sock)*(size_t)listensock_count);
	if(!listensock_new){
		return 1;
	}
	listensock = listensock_new;

	for(i=0; i<listener->sock_count; i++){
		if(listener->socks[i] == INVALID_SOCKET){
			return 1;
		}
		listensock[listensock_index].sock = listener->socks[i];
		listensock[listensock_index].listener = listener;
#ifdef WITH_EPOLL
		listensock[listensock_index].ident = id_listener;
#endif
		listensock_index++;
	}
	return MOSQ_ERR_SUCCESS;
}


#ifdef WITH_WEBSOCKETS
void listeners__add_websockets(struct lws_context *ws_context, mosq_sock_t fd)
{
	int i;
	struct mosquitto__listener *listener = NULL;
	struct mosquitto__listener_sock *listensock_new;

	/* Don't add more listeners after we've started the main loop */
	if(run || ws_context == NULL) return;

	/* Find context */
	for(i=0; i<db.config->listener_count; i++){
		if(db.config->listeners[i].ws_in_init){
			listener = &db.config->listeners[i];
			break;
		}
	}
	if(listener == NULL){
		return;
	}

	listensock_count++;
	listensock_new = mosquitto__realloc(listensock, sizeof(struct mosquitto__listener_sock)*(size_t)listensock_count);
	if(!listensock_new){
		return;
	}
	listensock = listensock_new;

	listensock[listensock_index].sock = fd;
	listensock[listensock_index].listener = listener;
#ifdef WITH_EPOLL
	listensock[listensock_index].ident = id_listener_ws;
#endif
	listensock_index++;
}
#endif

static int listeners__add_local(const char *host, uint16_t port)
{
	struct mosquitto__listener *listeners;
	listeners = db.config->listeners;

	listener__set_defaults(&listeners[db.config->listener_count]);
	listeners[db.config->listener_count].security_options.allow_anonymous = true;
	listeners[db.config->listener_count].port = port;
	listeners[db.config->listener_count].host = mosquitto__strdup(host);
	if(listeners[db.config->listener_count].host == NULL){
		return MOSQ_ERR_NOMEM;
	}
	if(listeners__start_single_mqtt(&listeners[db.config->listener_count])){
		mosquitto__free(listeners[db.config->listener_count].host);
		listeners[db.config->listener_count].host = NULL;
		return MOSQ_ERR_UNKNOWN;
	}
	db.config->listener_count++;
	return MOSQ_ERR_SUCCESS;
}

static int listeners__start_local_only(void)
{
	/* Attempt to open listeners bound to 127.0.0.1 and ::1 only */
	int i;
	int rc;
	struct mosquitto__listener *listeners;

	listeners = mosquitto__realloc(db.config->listeners, 2*sizeof(struct mosquitto__listener));
	if(listeners == NULL){
		return MOSQ_ERR_NOMEM;
	}
	memset(listeners, 0, 2*sizeof(struct mosquitto__listener));
	db.config->listener_count = 0;
	db.config->listeners = listeners;

	log__printf(NULL, MOSQ_LOG_WARNING, "Starting in local only mode. Connections will only be possible from clients running on this machine.");
	log__printf(NULL, MOSQ_LOG_WARNING, "Create a configuration file which defines a listener to allow remote access.");
	log__printf(NULL, MOSQ_LOG_WARNING, "For more details see https://mosquitto.org/documentation/authentication-methods/");
	if(db.config->cmd_port_count == 0){
		rc = listeners__add_local("127.0.0.1", 1883);
		if(rc == MOSQ_ERR_NOMEM) return MOSQ_ERR_NOMEM;
		rc = listeners__add_local("::1", 1883);
		if(rc == MOSQ_ERR_NOMEM) return MOSQ_ERR_NOMEM;
	}else{
		for(i=0; i<db.config->cmd_port_count; i++){
			rc = listeners__add_local("127.0.0.1", db.config->cmd_port[i]);
			if(rc == MOSQ_ERR_NOMEM) return MOSQ_ERR_NOMEM;
			rc = listeners__add_local("::1", db.config->cmd_port[i]);
			if(rc == MOSQ_ERR_NOMEM) return MOSQ_ERR_NOMEM;
		}
	}

	if(db.config->listener_count > 0){
		return MOSQ_ERR_SUCCESS;
	}else{
		return MOSQ_ERR_UNKNOWN;
	}
}


static int listeners__start(void)
{
	int i;

	listensock_count = 0;

	if(db.config->local_only){
		if(listeners__start_local_only()){
			db__close();
			if(db.config->pid_file){
				(void)remove(db.config->pid_file);
			}
			return 1;
		}
		return MOSQ_ERR_SUCCESS;
	}

	for(i=0; i<db.config->listener_count; i++){
		if(db.config->listeners[i].protocol == mp_mqtt){
			if(listeners__start_single_mqtt(&db.config->listeners[i])){
				db__close();
				if(db.config->pid_file){
					(void)remove(db.config->pid_file);
				}
				return 1;
			}
		}else if(db.config->listeners[i].protocol == mp_websockets){
#ifdef WITH_WEBSOCKETS
			mosq_websockets_init(&db.config->listeners[i], db.config);
			if(!db.config->listeners[i].ws_context){
				log__printf(NULL, MOSQ_LOG_ERR, "Error: Unable to create websockets listener on port %d.", db.config->listeners[i].port);
				return 1;
			}
#endif
		}
	}
	if(listensock == NULL){
		log__printf(NULL, MOSQ_LOG_ERR, "Error: Unable to start any listening sockets, exiting.");
		return 1;
	}
	return MOSQ_ERR_SUCCESS;
}


static void listeners__stop(void)
{
	int i;

	for(i=0; i<db.config->listener_count; i++){
#ifdef WITH_WEBSOCKETS
		if(db.config->listeners[i].ws_context){
			lws_context_destroy(db.config->listeners[i].ws_context);
		}
		mosquitto__free(db.config->listeners[i].ws_protocol);
#endif
#ifdef WITH_UNIX_SOCKETS
		if(db.config->listeners[i].unix_socket_path != NULL){
			unlink(db.config->listeners[i].unix_socket_path);
		}
#endif
	}

	for(i=0; i<listensock_count; i++){
		if(listensock[i].sock != INVALID_SOCKET){
			COMPAT_CLOSE(listensock[i].sock);
		}
	}
	mosquitto__free(listensock);
}


static void signal__setup(void)
{
	signal(SIGINT, handle_sigint);
	signal(SIGTERM, handle_sigint);
#ifdef SIGHUP
	signal(SIGHUP, handle_sighup);
#endif
#ifndef WIN32
	signal(SIGUSR1, handle_sigusr1);
	signal(SIGUSR2, handle_sigusr2);
	signal(SIGPIPE, SIG_IGN);
#endif
#ifdef WIN32
	CreateThread(NULL, 0, SigThreadProc, NULL, 0, NULL);
#endif
}


static int pid__write(void)
{
	FILE *pid;

	if(db.config->pid_file){
		pid = mosquitto__fopen(db.config->pid_file, "wt", false);
		if(pid){
			fprintf(pid, "%d", getpid());
			fclose(pid);
		}else{
			log__printf(NULL, MOSQ_LOG_ERR, "Error: Unable to write pid file.");
			return 1;
		}
	}
	return MOSQ_ERR_SUCCESS;
}


int main(int argc, char *argv[])
{
	struct mosquitto__config config;
#ifdef WITH_BRIDGE
	int i;
#endif
	int rc;
#ifdef WIN32
	SYSTEMTIME st;
#else
	struct timeval tv;
#endif
	struct mosquitto *ctxt, *ctxt_tmp;

#if defined(WIN32) || defined(__CYGWIN__)
	if(argc == 2){
		if(!strcmp(argv[1], "run")){
			service_run();
			return 0;
		}else if(!strcmp(argv[1], "install")){
			service_install();
			return 0;
		}else if(!strcmp(argv[1], "uninstall")){
			service_uninstall();
			return 0;
		}
	}
#endif


#ifdef WIN32
	GetSystemTime(&st);
	srand(st.wSecond + st.wMilliseconds);
#else
	gettimeofday(&tv, NULL);
	srand((unsigned int)(tv.tv_sec + tv.tv_usec));
#endif

#ifdef WIN32
	_setmaxstdio(2048);
#endif

	memset(&db, 0, sizeof(struct mosquitto_db));
	db.now_s = mosquitto_time();
	db.now_real_s = time(NULL);

	net__broker_init();

	config__init(&config);
	rc = config__parse_args(&config, argc, argv);
	if(rc != MOSQ_ERR_SUCCESS) return rc;
	db.config = &config;

	/* Drop privileges permanently immediately after the config is loaded.
	 * This requires the user to ensure that all certificates, log locations,
	 * etc. are accessible my the `mosquitto` or other unprivileged user.
	 */
	rc = drop_privileges(&config);
	if(rc != MOSQ_ERR_SUCCESS) return rc;

	if(config.daemon){
		mosquitto__daemonise();
	}

	if(pid__write()) return 1;

	rc = db__open(&config);
	if(rc != MOSQ_ERR_SUCCESS){
		log__printf(NULL, MOSQ_LOG_ERR, "Error: Couldn't open database.");
		return rc;
	}

	/* Initialise logging only after initialising the database in case we're
	 * logging to topics */
	if(log__init(&config)){
		rc = 1;
		return rc;
	}
	log__printf(NULL, MOSQ_LOG_INFO, "mosquitto version %s starting", VERSION);
	if(db.config_file){
		log__printf(NULL, MOSQ_LOG_INFO, "Config loaded from %s.", db.config_file);
	}else{
		log__printf(NULL, MOSQ_LOG_INFO, "Using default config.");
	}

	rc = mosquitto_security_module_init();
	if(rc) return rc;
	rc = mosquitto_security_init(false);
	if(rc) return rc;

	/* After loading persisted clients and ACLs, try to associate them,
	 * so persisted subscriptions can start storing messages */
	HASH_ITER(hh_id, db.contexts_by_id, ctxt, ctxt_tmp){
		if(ctxt && !ctxt->clean_start && ctxt->username){
			rc = acl__find_acls(ctxt);
			if(rc){
				log__printf(NULL, MOSQ_LOG_WARNING, "Failed to associate persisted user %s with ACLs, "
					"likely due to changed ports while using a per_listener_settings configuration.", ctxt->username);
			}
		}
	}

#ifdef WITH_SYS_TREE
	sys_tree__init();
#endif

	if(listeners__start()) return 1;

	rc = mux__init(listensock, listensock_count);
	if(rc) return rc;

	signal__setup();

#ifdef WITH_BRIDGE
	bridge__start_all();
#endif

	log__printf(NULL, MOSQ_LOG_INFO, "mosquitto version %s running", VERSION);
#ifdef WITH_SYSTEMD
	sd_notify(0, "READY=1");
#endif

	run = 1;
	rc = mosquitto_main_loop(listensock, listensock_count);

	log__printf(NULL, MOSQ_LOG_INFO, "mosquitto version %s terminating", VERSION);

	/* FIXME - this isn't quite right, all wills with will delay zero should be
	 * sent now, but those with positive will delay should be persisted and
	 * restored, pending the client reconnecting in time. */
	HASH_ITER(hh_id, db.contexts_by_id, ctxt, ctxt_tmp){
		context__send_will(ctxt);
	}
	will_delay__send_all();

#ifdef WITH_PERSISTENCE
	persist__backup(true);
#endif
	session_expiry__remove_all();

	listeners__stop();

	HASH_ITER(hh_id, db.contexts_by_id, ctxt, ctxt_tmp){
#ifdef WITH_WEBSOCKETS
		if(!ctxt->wsi)
#endif
		{
			context__cleanup(ctxt, true);
		}
	}
	HASH_ITER(hh_sock, db.contexts_by_sock, ctxt, ctxt_tmp){
		context__cleanup(ctxt, true);
	}
#ifdef WITH_BRIDGE
	for(i=0; i<db.bridge_count; i++){
		if(db.bridges[i]){
			context__cleanup(db.bridges[i], true);
		}
	}
	mosquitto__free(db.bridges);
#endif
	context__free_disused();

	db__close();

	mosquitto_security_module_cleanup();

	if(config.pid_file){
		(void)remove(config.pid_file);
	}

	log__close(&config);
	config__cleanup(db.config);
	net__broker_cleanup();

	return rc;
}

#ifdef WIN32
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
	char **argv;
	int argc = 1;
	char *token;
	char *saveptr = NULL;
	int rc;

	UNUSED(hInstance);
	UNUSED(hPrevInstance);
	UNUSED(nCmdShow);

	argv = mosquitto__malloc(sizeof(char *)*1);
	argv[0] = "mosquitto";
	token = strtok_r(lpCmdLine, " ", &saveptr);
	while(token){
		argc++;
		argv = mosquitto__realloc(argv, sizeof(char *)*argc);
		if(!argv){
			fprintf(stderr, "Error: Out of memory.\n");
			return MOSQ_ERR_NOMEM;
		}
		argv[argc-1] = token;
		token = strtok_r(NULL, " ", &saveptr);
	}
	rc = main(argc, argv);
	mosquitto__free(argv);
	return rc;
}
#endif