X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=server.c;h=245562631d18122084d97ca2af9f9afdec2cf59f;hp=c46966ea8e2343f38366b14f34d360dce6d67026;hb=c00d7e25de7006d6f88aafb2b485057377a70324;hpb=bc6c214340c1760203b24097c2066abfcaa1c539

diff --git a/server.c b/server.c
index c46966ea..24556263 100644
--- a/server.c
+++ b/server.c
@@ -1,418 +1,524 @@
 /*
- * Copyright (C) 1997-2006 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 1997-2009 Andre Noll <maan@systemlinux.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 2 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, write to the Free Software
- *     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
+ * Licensed under the GPL v2. For licencing details see COPYING.
  */
 
-/** \file server.c Paraslash's main server */
+/** \file server.c Paraslash's main server. */
 
 
-/** \mainpage Paraslash API Reference
+/**
+ * \mainpage Paraslash API Reference
+ *
+ * Starting points for getting an overview:
+ *
+ *
+ * 	- The main programs: \ref server.c, \ref audiod.c, \ref client.c,
+ *	  \ref audioc.c, \ref afh.c
+ *	- Server: \ref server_command, \ref sender,
+ *	- Audio file selector: \ref audio_format_handler, \ref mood, \ref afs_table,
+ *	- Client: \ref receiver, \ref receiver_node, \ref filter, \ref filter_node.
  *
- *  Good starting points for reading are probably \ref dbtool, \ref sender,
- *  \ref receiver, \ref receiver_node, \ref filter, \ref filter_node.
  *
+ * The gory details, listed by topic:
+ *
+ * 	- Audio format handlers: \ref send_common.c \ref mp3_afh.c, \ref ogg_afh.c, \ref aac_afh.c,
+ * 	- Decoders: \ref mp3dec_filter.c, \ref oggdec_filter.c, \ref aacdec_filter.c,
+ *	- Volume normalizer: \ref compress_filter.c,
+ *	- Output: \ref alsa_write.c, \ref osx_write.c,
+ * 	- http: \ref http_recv.c, \ref http_send.c,
+ *	- udp: \ref udp_recv.c, \ref udp_send.c,
+ *	- dccp: \ref dccp_recv.c, \ref dccp_send.c,
+ *	- Audio file selector: \ref afs.c, \ref aft.c, \ref mood.c,
+ *	- Afs structures: \ref afs_table, \ref audio_file_data,
+ *	  \ref afs_info \ref afh_info,
+ *	- Afs tables: \ref aft.c, \ref mood.c, \ref playlist.c,
+ *	  \ref attribute.c, \ref score.c,
+ *	- The virtual streaming system: \ref vss.c, \ref chunk_queue.c.
+ *
+ * Lower levels:
+ *
+ *	- Scheduling: \ref sched.c, \ref sched.h,
+ * 	- Networking: \ref net.c,
+ *	- File descriptors: \ref fd.c,
+ *	- Signals: \ref signal.c,
+ *	- Daemons: \ref daemon.c,
+ *	- Strings: \ref string.c, \ref string.h,
+ *	- Time: \ref time.c,
+ *	- Spawning processes: \ref exec.c,
+ *	- Inter process communication: \ref ipc.c,
+ *	- Blob tables: \ref blob.c,
+ *	- The error subssystem: \ref error.h.
+ *	- Access control for paraslash senders: \ref acl.c, \ref acl.h.
+ *
+ * Low-level data structures:
+ *
+ *	- Doubly linked lists: \ref list.h,
+ *	- Ring buffer: \ref ringbuffer.c, \ref ringbuffer.h,
+ *	- Hashing: \ref hash.h, \ref sha1.h, \ref sha1.c,
+ *	- Crypto: \ref crypt.c.
+ *	- Forward error correction: \ref fec.c
  */
 
+#include <signal.h>
+#include <dirent.h>
+#include <sys/time.h>
+#include <openssl/rc4.h>
+#include <osl.h>
 
-
+#include "para.h"
+#include "error.h"
+#include "crypt.h"
 #include "server.cmdline.h"
-#include "db.h"
-#include "server.h"
+#include "afh.h"
+#include "string.h"
 #include "afs.h"
+#include "server.h"
+#include "vss.h"
 #include "config.h"
 #include "close_on_fork.h"
+#include "list.h"
 #include "send.h"
-#include "error.h"
 #include "net.h"
 #include "daemon.h"
-#include "string.h"
 #include "ipc.h"
+#include "fd.h"
+#include "sched.h"
+#include "signal.h"
+#include "user_list.h"
+#include "color.h"
 
-/** define the array of error lists needed by para_server */
+/** Define the array of error lists needed by para_server. */
 INIT_SERVER_ERRLISTS;
 
-/** shut down non-authorized connections after that many seconds */
+/** Shut down non-authorized connections after that many seconds. */
 #define ALARM_TIMEOUT 10
 
-/* these are exported to afs/command/dbtool */
+/**
+ * Pointer to shared memory area for communication between para_server
+ * and its children. Exported to vss.c. command.c and to afs.
+ */
 struct misc_meta_data *mmd;
-/** the configuration of para_server
+
+/**
+ * The configuration of para_server
  *
- * It also contains the options for all database tools and all supported
- * senders.
-*/
-struct gengetopt_args_info conf;
-char *user_list = NULL;
-extern void http_send_init(struct sender *);
-extern void ortp_send_init(struct sender *);
-extern struct audio_format afl[];
-
-/** the list of supported database tools */
-struct dbtool dblist[] = {
-	{
-		.name = "random",
-		.init = random_dbtool_init,
-		.update_audio_file = NULL,
-	},
-	{
-		.name = "plm",
-		.init = plm_dbtool_init,
-		.update_audio_file = NULL,
-		.pre_select = NULL,
-		.post_select = NULL,
-	},
-#ifdef HAVE_MYSQL
-	{
-		.name = "mysql",
-		.init = mysql_dbtool_init,
-		.update_audio_file = NULL,
-		.pre_select = NULL,
-		.post_select = NULL,
-	},
-#endif
-	{
-		.name = NULL,
-	}
-};
+ * It also contains the options for the audio file selector, audio format
+ * handler and all supported senders.
+ */
+struct server_args_info conf;
 
-/** the list of supported senders */
-struct sender senders[] = {
-	{
-		.name = "http",
-		.init = http_send_init,
-	},
-#ifdef HAVE_ORTP
-	{
-		.name = "ortp",
-		.init = ortp_send_init,
-	},
-#endif
-	{
-		.name = NULL,
-	}
-};
+/** A random value used in child context for authentication. */
+uint32_t afs_socket_cookie;
 
+/** The mutex protecting the shared memory area containing the mmd struct. */
+int mmd_mutex;
 
-/* global variables for server-internal use */
-static FILE *logfile;
-static int mmd_mutex, mmd_shm_id;
-static int signal_pipe;
+/** The file containing user information (public key, permissions). */
+static char *user_list_file = NULL;
 
-/**
- * para_server's log function
- *
- * \param ll the log level
- * \param fmt the format string describing the log message
- */
-void para_log(int ll, char* fmt,...)
+
+/** The task responsible for server command handling. */
+struct server_command_task {
+	/** TCP port on which para_server listens for connections. */
+	int listen_fd;
+	/** Copied from para_server's main function. */
+	int argc;
+	/** Argument vector passed to para_server's main function. */
+	char **argv;
+	/** The command task structure for scheduling. */
+	struct task task;
+};
+
+static int want_colors(void)
 {
-	va_list argp;
-	FILE *outfd;
-	struct tm *tm;
-	time_t t1;
-	char str[MAXLINE] = "";
-	pid_t mypid;
-
-	if (ll < conf.loglevel_arg)
-		return;
-	if (!logfile) {
-		if (ll < WARNING)
-			outfd = stdout;
-		else
-			outfd = stderr;
-	} else
-		outfd = logfile;
-	if (conf.daemon_given && !logfile)
+	if (conf.color_arg == color_arg_no)
+		return 0;
+	if (conf.color_arg == color_arg_yes)
+		return 1;
+	if (conf.logfile_given)
+		return 0;
+	return isatty(STDERR_FILENO);
+}
+
+static void init_colors_or_die(void)
+{
+	int ret, i;
+
+	if (!want_colors())
 		return;
-	time(&t1);
-	tm = localtime(&t1);
-	strftime(str, MAXLINE, "%b %d %H:%M:%S", tm);
-	fprintf(outfd, "%s ", str);
-	if (conf.loglevel_arg <= INFO)
-		fprintf(outfd, "%i: ", ll);
-	mypid = getpid();
-	if (conf.loglevel_arg <= INFO)
-		fprintf(outfd, "(%d) ", mypid);
-	va_start(argp, fmt);
-	vfprintf(outfd, fmt, argp);
-	va_end(argp);
+	daemon_set_flag(DF_COLOR_LOG);
+	daemon_set_default_log_colors();
+	for (i = 0; i < conf.log_color_given; i++) {
+		ret = daemon_set_log_color(conf.log_color_arg[i]);
+		if (ret < 0)
+			exit(EXIT_FAILURE);
+	}
 }
 
 /*
  * setup shared memory area and get mutex for locking
  */
-static void shm_init(void)
+static void init_ipc_or_die(void)
 {
 	void *shm;
-	int ret = shm_new(sizeof(struct misc_meta_data));
+	int shmid, ret = shm_new(sizeof(struct misc_meta_data));
 
 	if (ret < 0)
 		goto err_out;
-
-	ret = shm_attach(ret, ATTACH_RW, &shm);
+	shmid = ret;
+	ret = shm_attach(shmid, ATTACH_RW, &shm);
+	shm_destroy(shmid);
 	if (ret < 0)
 		goto err_out;
 	mmd = shm;
-	mmd_shm_id = ret;
 
 	ret = mutex_new();
 	if (ret < 0)
 		goto err_out;
 	mmd_mutex = ret;
 
-	mmd->dbt_num = 0;
 	mmd->num_played = 0;
 	mmd->num_commands = 0;
 	mmd->events = 0;
 	mmd->num_connects = 0;
 	mmd->active_connections = 0;
-	strcpy(mmd->filename, "(none)");
-	mmd->audio_format = -1;
-	mmd->afs_status_flags = AFS_NEXT;
-	mmd->new_afs_status_flags = AFS_NEXT;
-	mmd->sender_cmd_data.cmd_num = -1;
+	mmd->vss_status_flags = VSS_NEXT;
+	mmd->new_vss_status_flags = VSS_NEXT;
 	return;
 err_out:
-	PARA_EMERG_LOG("%s", PARA_STRERROR(-ret));
+	PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 	exit(EXIT_FAILURE);
 }
 
 /**
- * lock the shared memory area containing the mmd struct
+ * (Re-)read the server configuration files.
  *
- * \sa semop(2), struct misc_meta_data
- */
-void mmd_lock(void)
-{
-	mutex_lock(mmd_mutex);
-}
-
-/**
- * unlock the shared memory area containing the mmd struct
+ * \param override Passed to gengetopt to activate the override feature.
  *
- * \sa semop(2), struct misc_meta_data
+ * This function also re-opens the logfile and sets the global \a
+ * user_list_file variable.
  */
-
-void mmd_unlock(void)
-{
-	mutex_unlock(mmd_mutex);
-}
-
-static void parse_config(int override)
+void parse_config_or_die(int override)
 {
 	char *home = para_homedir();
-	struct stat statbuf;
 	int ret;
 	char *cf;
 
+	daemon_close_log();
 	if (conf.config_file_given)
-		cf = conf.config_file_arg;
+		cf = para_strdup(conf.config_file_arg);
 	else
 		cf = make_message("%s/.paraslash/server.conf", home);
-	free(user_list);
+	free(user_list_file);
 	if (!conf.user_list_given)
-		user_list = make_message("%s/.paraslash/server.users", home);
+		user_list_file = make_message("%s/.paraslash/server.users", home);
 	else
-		user_list = para_strdup(conf.user_list_arg);
-	ret = stat(cf, &statbuf);
-	if (ret && conf.config_file_given) {
+		user_list_file = para_strdup(conf.user_list_arg);
+	ret = file_exists(cf);
+	if (conf.config_file_given && !ret)  {
 		ret = -1;
-		PARA_EMERG_LOG("can not stat config file %s\n", cf);
+		PARA_EMERG_LOG("can not read config file %s\n", cf);
 		goto out;
 	}
-	if (!ret) {
+	if (ret) {
 		int tmp = conf.daemon_given;
-		cmdline_parser_configfile(cf, &conf, override, 0, 0);
+		struct server_cmdline_parser_params params = {
+			.override = override,
+			.initialize = 0,
+			.check_required = 1,
+			.check_ambiguity = 0,
+			.print_errors = !conf.daemon_given
+		};
+		server_cmdline_parser_config_file(cf, &conf, &params);
 		conf.daemon_given = tmp;
 	}
-	/* logfile */
-	if (!conf.logfile_given && conf.daemon_given) {
-		ret = -1;
-		PARA_EMERG_LOG("%s", "daemon, but no log file\n");
-		goto out;
+	if (conf.logfile_given) {
+		daemon_set_logfile(conf.logfile_arg);
+		daemon_open_log_or_die();
 	}
-	if (conf.logfile_given)
-		logfile = open_log(conf.logfile_arg);
+	daemon_set_loglevel(conf.loglevel_arg);
+	init_colors_or_die();
+	daemon_set_flag(DF_LOG_PID);
+	daemon_set_flag(DF_LOG_LL);
+	daemon_set_flag(DF_LOG_TIME);
 	ret = 1;
 out:
 	free(cf);
 	free(home);
 	if (ret > 0)
 		return;
-	free(user_list);
-	user_list = NULL;
+	free(user_list_file);
+	user_list_file = NULL;
 	exit(EXIT_FAILURE);
 }
 
-static void setup_signal_handling(void)
+static void signal_pre_select(struct sched *s, struct task *t)
 {
-	int ret = 0;
-
-	signal_pipe = para_signal_init();
-//	fcntl(signal_pipe, F_SETFL, O_NONBLOCK);
-	PARA_NOTICE_LOG("%s", "setting up signal handlers\n");
-	ret += para_install_sighandler(SIGINT);
-	ret += para_install_sighandler(SIGTERM);
-	ret += para_install_sighandler(SIGHUP);
-	ret += para_install_sighandler(SIGCHLD);
-	ret += para_install_sighandler(SIGUSR1);
-	signal(SIGPIPE, SIG_IGN);
-	if (ret != 5) {
-		PARA_EMERG_LOG("%s", "could not install signal handlers\n");
-		exit(EXIT_FAILURE);
-	}
+	struct signal_task *st = container_of(t, struct signal_task, task);
+	para_fd_set(st->fd, &s->rfds, &s->max_fileno);
 }
 
-static void init_dbtool(void)
+/*
+ * called when server gets SIGHUP or when client invokes hup command.
+ */
+static void handle_sighup(void)
 {
-	int i;
-
-	mmd->dbt_change = -1; /* no change nec., set to new dbt num by com_cdt */
-	if (!dblist[1].name)
-		goto random;
-	if (conf.dbtool_given) {
-		for (i = 0; dblist[i].name; i++) {
-			if (strcmp(dblist[i].name, conf.dbtool_arg))
+	PARA_NOTICE_LOG("SIGHUP\n");
+	parse_config_or_die(1); /* reopens log */
+	init_user_list(user_list_file); /* reload user list */
+	if (mmd->afs_pid)
+		kill(mmd->afs_pid, SIGHUP);
+}
+
+static void signal_post_select(struct sched *s, struct task *t)
+{
+	struct signal_task *st = container_of(t, struct signal_task, task);
+
+	if (!FD_ISSET(st->fd, &s->rfds))
+		return;
+
+	st->signum = para_next_signal();
+	switch (st->signum) {
+	case SIGHUP:
+		handle_sighup();
+		break;
+	case SIGCHLD:
+		for (;;) {
+			pid_t pid;
+			int ret = para_reap_child(&pid);
+			if (ret <= 0)
+				break;
+			if (pid != mmd->afs_pid)
 				continue;
-			PARA_NOTICE_LOG("initializing %s database tool\n",
-				dblist[i].name);
-			if (dblist[i].init(&dblist[i]) < 0) {
-				PARA_WARNING_LOG("init %s failed",
-					dblist[i].name);
-				goto random;
-			}
-			mmd->dbt_num = i;
-			return;
-		}
-		PARA_WARNING_LOG("%s", "no such dbtool, switching to random\n");
-		goto random;
-	}
-	/* use the first dbtool that works
-	 * (assuming that random always works)
-	 */
-	for (i = 1; dblist[i].name; i++) {
-		int ret = dblist[i].init(&dblist[i]);
-		if (ret >= 0) {
-			PARA_INFO_LOG("initialized %s\n", dblist[i].name);
-			mmd->dbt_num = i;
-			return;
+			PARA_EMERG_LOG("fatal: afs died\n");
+			kill(0, SIGTERM);
+			goto cleanup;
 		}
-		PARA_CRIT_LOG("%s init failed: %s\n", dblist[i].name,
-			PARA_STRERROR(-ret));
+		break;
+	/* die on sigint/sigterm. Kill all children too. */
+	case SIGINT:
+	case SIGTERM:
+		PARA_EMERG_LOG("terminating on signal %d\n", st->signum);
+		kill(0, SIGTERM);
+		/*
+		 * We must wait for afs because afs catches SIGINT/SIGTERM.
+		 * Before reacting to the signal, afs might want to use the
+		 * shared memory area and the mmd mutex.  If we destroy this
+		 * mutex too early and afs tries to lock the shared memory
+		 * area, the call to mutex_lock() will fail and terminate the
+		 * afs process. This leads to dirty osl tables.
+		 *
+		 * There's no such problem with the other children of the
+		 * server process (the command handlers) as these reset their
+		 * SIGINT/SIGTERM handlers to the default action, i.e.  these
+		 * processes get killed immediately by the above kill().
+		 */
+		PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
+			(int)mmd->afs_pid);
+		waitpid(mmd->afs_pid, NULL, 0);
+cleanup:
+		free(mmd->afd.afhi.chunk_table);
+		close_listed_fds();
+		mutex_destroy(mmd_mutex);
+		shm_detach(mmd);
+		exit(EXIT_FAILURE);
 	}
-random:
-	mmd->dbt_num = 0;
-	dblist[0].init(&dblist[0]); /* always successful */
 }
 
-static unsigned init_network(void)
+static void init_signal_task(void)
 {
-	int sockfd = init_tcp_socket(conf.port_arg);
+	static struct signal_task signal_task_struct,
+		*st = &signal_task_struct;
+
+	st->task.pre_select = signal_pre_select;
+	st->task.post_select = signal_post_select;
+	sprintf(st->task.status, "signal task");
+
+	PARA_NOTICE_LOG("setting up signal handling\n");
+	st->fd = para_signal_init(); /* always successful */
+	para_install_sighandler(SIGINT);
+	para_install_sighandler(SIGTERM);
+	para_install_sighandler(SIGHUP);
+	para_install_sighandler(SIGCHLD);
+	para_sigaction(SIGPIPE, SIG_IGN);
+	add_close_on_fork_list(st->fd);
+	register_task(&st->task);
+}
 
-	if (sockfd < 0)
-		exit(EXIT_FAILURE);
-	return sockfd;
+static void command_pre_select(struct sched *s, struct task *t)
+{
+	struct server_command_task *sct = container_of(t, struct server_command_task, task);
+	para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
 }
 
-static void init_random_seed(void)
+static void command_post_select(struct sched *s, struct task *t)
 {
-	int fd, ret = -1, len = sizeof(unsigned int);
-	unsigned int seed;
+	struct server_command_task *sct = container_of(t, struct server_command_task, task);
 
-	fd = open("/dev/random", O_RDONLY);
-	if (fd < 0)
+	int new_fd, ret, i;
+	char *peer_name;
+	pid_t child_pid;
+	uint32_t *chunk_table;
+
+	if (!FD_ISSET(sct->listen_fd, &s->rfds))
+		return;
+	ret = para_accept(sct->listen_fd, NULL, 0);
+	if (ret < 0)
 		goto out;
-	ret = -2;
-	if (read(fd, &seed, len) != len)
+	new_fd = ret;
+	peer_name = remote_name(new_fd);
+	PARA_INFO_LOG("got connection from %s, forking\n", peer_name);
+	mmd->num_connects++;
+	mmd->active_connections++;
+	/*
+	 * The chunk table is a pointer located in the mmd struct that points
+	 * to dynamically allocated memory, i.e. it must be freed by the parent
+	 * and the child. However, as the mmd struct is in a shared memory
+	 * area, there's no guarantee that after the fork this pointer is still
+	 * valid in child context. As it is not used in the child anyway, we
+	 * save it to a local variable before the fork and free the memory via
+	 * that copy in the child directly after the fork.
+	 */
+	chunk_table = mmd->afd.afhi.chunk_table;
+	child_pid = fork();
+	if (child_pid < 0) {
+		ret = -ERRNO_TO_PARA_ERROR(errno);
 		goto out;
-	srandom(seed);
-	ret = 1;
-out:
-	if (fd >= 0)
-		close(fd);
-	if (ret > 0)
+	}
+	if (child_pid) {
+		close(new_fd);
+		/* parent keeps accepting connections */
 		return;
-	PARA_EMERG_LOG("can not seed pseudo random generator (ret = %d)\n",
-		ret);
+	}
+	/* mmd might already have changed at this point */
+	free(chunk_table);
+	alarm(ALARM_TIMEOUT);
+	close_listed_fds();
+	para_signal_shutdown();
+	/*
+	 * put info on who we are serving into argv[0] to make
+	 * client ip visible in top/ps
+	 */
+	for (i = sct->argc - 1; i >= 0; i--)
+		memset(sct->argv[i], 0, strlen(sct->argv[i]));
+	sprintf(sct->argv[0], "para_server (serving %s)", peer_name);
+	return handle_connect(new_fd, peer_name);
+out:
+	if (ret < 0)
+		PARA_CRIT_LOG("%s\n", para_strerror(-ret));
+}
+
+static void init_server_command_task(int argc, char **argv)
+{
+	int ret;
+	static struct server_command_task server_command_task_struct,
+		*sct = &server_command_task_struct;
+
+	PARA_NOTICE_LOG("initializing tcp command socket\n");
+	sct->task.pre_select = command_pre_select;
+	sct->task.post_select = command_post_select;
+	sct->argc = argc;
+	sct->argv = argv;
+	ret = para_listen(AF_UNSPEC, IPPROTO_TCP, conf.port_arg);
+	if (ret < 0)
+		goto err;
+	sct->listen_fd = ret;
+	ret = mark_fd_nonblocking(sct->listen_fd);
+	if (ret < 0)
+		goto err;
+	add_close_on_fork_list(sct->listen_fd); /* child doesn't need the listener */
+	register_task(&sct->task);
+	return;
+err:
+	PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 	exit(EXIT_FAILURE);
 }
 
-static unsigned do_inits(int argc, char **argv)
+static int init_afs(void)
 {
-	/* connector's address information */
-	int sockfd;
+	int ret, afs_server_socket[2];
 
-	init_random_seed();
-	/* parse command line options */
-	cmdline_parser(argc, argv, &conf);
-	para_drop_privileges(conf.user_arg);
-	/* parse config file, open log and set defaults */
-	parse_config(0);
-	log_welcome("para_server", conf.loglevel_arg);
-	shm_init(); /* init mmd struct */
-	server_uptime(UPTIME_SET); /* reset server uptime */
-	/* become daemon */
-	if (conf.daemon_given)
-		daemon_init();
-	init_dbtool();
-	PARA_NOTICE_LOG("%s", "initializing audio file sender\n");
-	/* audio file sender */
-	afs_init();
-	mmd->server_pid = getpid();
-	setup_signal_handling();
-	mmd_lock();
-	/* init network socket */
-	PARA_NOTICE_LOG("%s", "initializing tcp command socket\n");
-	sockfd = init_network();
-	if (conf.autoplay_given) {
-		mmd->afs_status_flags |= AFS_PLAYING;
-		mmd->new_afs_status_flags |= AFS_PLAYING;
+	ret = socketpair(PF_UNIX, SOCK_DGRAM, 0, afs_server_socket);
+	if (ret < 0)
+		exit(EXIT_FAILURE);
+	get_random_bytes_or_die((unsigned char *)&afs_socket_cookie,
+		sizeof(afs_socket_cookie));
+	mmd->afs_pid = fork();
+	if (mmd->afs_pid < 0)
+		exit(EXIT_FAILURE);
+	if (!mmd->afs_pid) { /* child (afs) */
+		close(afs_server_socket[0]);
+		afs_init(afs_socket_cookie, afs_server_socket[1]);
 	}
-	PARA_NOTICE_LOG("%s", "init complete\n");
-	return sockfd;
+	close(afs_server_socket[1]);
+	ret = mark_fd_nonblocking(afs_server_socket[0]);
+	if (ret < 0)
+		exit(EXIT_FAILURE);
+	add_close_on_fork_list(afs_server_socket[0]);
+	PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
+		afs_server_socket[0], (unsigned) afs_socket_cookie);
+	return afs_server_socket[0];
 }
 
-static void handle_dbt_change(void)
+__noreturn static void tmp_sigchld_handler(__a_unused int s)
 {
-	int ret, old = mmd->dbt_num, new = mmd->dbt_change;
-
-	dblist[old].shutdown();
-	ret = dblist[new].init(&dblist[new]);
-	mmd->dbt_change = -1; /* reset */
-	if (ret >= 0) {
-		mmd->dbt_num = new;
-		return;
-	}
-	/* init failed */
-	PARA_ERROR_LOG("%s -- switching to the random dbtool\n", PARA_STRERROR(-ret));
-	dblist[0].init(&dblist[0]);
-	mmd->dbt_num = 0;
+	PARA_EMERG_LOG("caught early SIGCHLD\n");
+	exit(EXIT_FAILURE);
 }
 
-/*
- * called when server gets SIGHUP or when client invokes hup command.
- */
-static void handle_sighup(void)
+static void server_init(int argc, char **argv)
 {
-	PARA_NOTICE_LOG("%s", "SIGHUP\n");
-	close_log(logfile); /* gets reopened if necessary by parse_config */
-	logfile = NULL;
-	parse_config(1); /* reopens log */
-	mmd->dbt_change = mmd->dbt_num; /* do not change dbtool */
-	handle_dbt_change(); /* force reloading dbtool */
+	struct server_cmdline_parser_params params = {
+		.override = 0,
+		.initialize = 1,
+		.check_required = 0,
+		.check_ambiguity = 0,
+		.print_errors = 1
+	};
+	int afs_socket;
+
+	valid_fd_012();
+	init_random_seed_or_die();
+	/* parse command line options */
+	server_cmdline_parser_ext(argc, argv, &conf, &params);
+	HANDLE_VERSION_FLAG("server", conf);
+	drop_privileges_or_die(conf.user_arg, conf.group_arg);
+	/* parse config file, open log and set defaults */
+	parse_config_or_die(0);
+	log_welcome("para_server");
+	init_ipc_or_die(); /* init mmd struct and mmd->lock */
+	/* make sure, the global now pointer is uptodate */
+	gettimeofday(now, NULL);
+	server_uptime(UPTIME_SET); /* reset server uptime */
+	init_user_list(user_list_file);
+	/* become daemon */
+	if (conf.daemon_given)
+		daemonize();
+	PARA_NOTICE_LOG("initializing audio format handlers\n");
+	afh_init();
+
+	/*
+	 * Although afs uses its own signal handling we must ignore SIGUSR1
+	 * _before_ the afs child process gets born by init_afs() below.  It's
+	 * racy to do this in the child because the parent might send SIGUSR1
+	 * before the child gets a chance to ignore this signal -- only the
+	 * good die young.
+	 */
+	para_sigaction(SIGUSR1, SIG_IGN);
+	/*
+	 * We have to install a SIGCHLD handler before the afs process is being
+	 * forked off. Otherwise, para_server does not notice if afs dies before
+	 * the SIGCHLD handler has been installed by init_signal_task() below.
+	 */
+	para_sigaction(SIGCHLD, tmp_sigchld_handler);
+	PARA_NOTICE_LOG("initializing the audio file selector\n");
+	afs_socket = init_afs();
+	init_signal_task();
+	PARA_NOTICE_LOG("initializing virtual streaming system\n");
+	init_vss_task(afs_socket);
+	init_server_command_task(argc, argv);
+	PARA_NOTICE_LOG("server init complete\n");
 }
 
 static void status_refresh(void)
@@ -422,152 +528,60 @@ static void status_refresh(void)
 
 	if (prev_events != mmd->events)
 		goto out;
-	if (mmd->new_afs_status_flags != mmd->afs_status_flags)
-		goto out;
+	if (mmd->new_vss_status_flags != mmd->vss_status_flags)
+		goto out_inc_events;
 	if (uptime / 60 != prev_uptime / 60)
-		goto out;
-	ret = 0;
+		goto out_inc_events;
+	return;
+out_inc_events:
+	mmd->events++;
 out:
 	prev_uptime = uptime;
 	prev_events = mmd->events;
-	mmd->afs_status_flags = mmd->new_afs_status_flags;
+	mmd->vss_status_flags = mmd->new_vss_status_flags;
 	if (ret) {
-		PARA_DEBUG_LOG("%d events, forcing status update, af = %d\n",
-			mmd->events, mmd->audio_format);
+		PARA_DEBUG_LOG("%d events, forcing status update\n",
+			mmd->events);
 		killpg(0, SIGUSR1);
 	}
 }
 
-/*
- * MAIN
- */
-int main(int argc, char *argv[])
+static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
+		struct timeval *timeout_tv)
 {
-	/* listen on sock_fd, new connection on new_fd */
-	int sockfd, new_fd;
-	struct sockaddr_in their_addr;
-	int err, i, max_fileno, ret;
-	pid_t chld_pid;
-	fd_set rfds, wfds;
-	struct timeval *timeout;
+	int ret;
 
-	valid_fd_012();
-	sockfd = do_inits(argc, argv);
-repeat:
-	/* check socket and signal pipe in any case */
-	FD_ZERO(&rfds);
-	FD_ZERO(&wfds);
-	FD_SET(sockfd, &rfds);
-	max_fileno = sockfd;
-	FD_SET(signal_pipe, &rfds);
-	max_fileno = MAX(max_fileno, signal_pipe);
-
-	timeout = afs_preselect();
 	status_refresh();
-	for (i = 0; senders[i].name; i++) {
-		if (senders[i].status != SENDER_ON)
-			continue;
-		if (!senders[i].pre_select)
-			continue;
-		senders[i].pre_select(mmd->audio_format >= 0?
-			&afl[mmd->audio_format] : NULL,
-			&max_fileno,
-			&rfds, &wfds);
-	}
-	if (dblist[mmd->dbt_num].pre_select) {
-		ret = dblist[mmd->dbt_num].pre_select(&rfds, &wfds);
-		max_fileno = MAX(max_fileno, ret);
-	}
-	mmd_unlock();
-//	PARA_DEBUG_LOG("%s: select (max = %i)\n", __func__, max_fileno);
-	ret = select(max_fileno + 1, &rfds, &wfds, NULL, timeout);
-	err = errno;
-	//PARA_DEBUG_LOG("%s: select returned  %i\n", __func__, ret);
-	mmd_lock();
-	if (mmd->dbt_change >= 0)
-		handle_dbt_change();
-	if (dblist[mmd->dbt_num].post_select)
-		dblist[mmd->dbt_num].post_select(&rfds, &wfds);
-	if (ret < 0 && err == EINTR)
-		goto repeat;
-	if (ret < 0) {
-		PARA_CRIT_LOG("select error (%s)\n", strerror(err));
-		goto repeat;
-	}
-	for (i = 0; senders[i].name; i++) {
-		if (senders[i].status != SENDER_ON)
-			continue;
-		if (!senders[i].post_select)
-			continue;
-		senders[i].post_select(mmd->audio_format >= 0?
-			&afl[mmd->audio_format] : NULL,
-			&rfds, &wfds);
-	}
-	if (!ret) {
-		afs_send_chunk();
-		status_refresh();
-	}
-	if (FD_ISSET(signal_pipe, &rfds)) {
-		int sig;
-		sig = para_next_signal();
-		switch (sig) {
-		case SIGHUP:
-			handle_sighup();
-			break;
-		case SIGCHLD:
-			para_reap_children();
-			break;
-		/* die on sigint/sigterm. Kill all children too. */
-		case SIGINT:
-		case SIGTERM:
-			PARA_EMERG_LOG("terminating on signal %d\n", sig);
-			kill(0, SIGTERM);
-			dblist[mmd->dbt_num].shutdown();
-			mutex_destroy(mmd_mutex);
-			shm_detach(mmd);
-			shm_destroy(mmd_shm_id);
-			exit(EXIT_FAILURE);
-		}
-	}
-	if (mmd->sender_cmd_data.cmd_num >= 0) {
-		int num = mmd->sender_cmd_data.cmd_num,
-			s = mmd->sender_cmd_data.sender_num;
+	mutex_unlock(mmd_mutex);
+	ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
+	mutex_lock(mmd_mutex);
+	return ret;
+}
 
-		if (senders[s].client_cmds[num])
-			senders[s].client_cmds[num](&mmd->sender_cmd_data);
-		mmd->sender_cmd_data.cmd_num = -1;
-	}
-	if (!FD_ISSET(sockfd, &rfds))
-		goto repeat;
-
-	new_fd = para_accept(sockfd, &their_addr, sizeof(struct sockaddr_in));
-	if (new_fd < 0)
-		goto repeat;
-	PARA_INFO_LOG("got connection from %s, forking\n",
-		inet_ntoa(their_addr.sin_addr));
-	mmd->num_connects++;
-	mmd->active_connections++;
-	random();
-	chld_pid = fork();
-	if (chld_pid < 0) {
-		PARA_CRIT_LOG("%s", "fork failed\n");
-		goto repeat;
-	}
-	if (chld_pid) {
-		close(new_fd);
-		/* parent keeps accepting connections */
-		goto repeat;
+/**
+ * The main function of para_server.
+ *
+ * \param argc Usual argument count.
+ * \param argv Usual argument vector.
+ *
+ * \return EXIT_SUCCESS or EXIT_FAILURE.
+ */
+int main(int argc, char *argv[])
+{
+	int ret;
+	static struct sched s = {
+		.default_timeout = {
+			.tv_sec = 1,
+			.tv_usec = 0
+		},
+		.select_function = server_select
+	};
+	server_init(argc, argv);
+	mutex_lock(mmd_mutex);
+	ret = schedule(&s);
+	if (ret < 0) {
+		PARA_EMERG_LOG("%s\n", para_strerror(-ret));
+		exit(EXIT_FAILURE);
 	}
-	alarm(ALARM_TIMEOUT);
-	close_listed_fds();
-	close(sockfd); /* child doesn't need the listener */
-	/*
-	 * put info on who we are serving into argv[0] to make
-	 * client ip visible in top/ps
-	 */
-	for (i = argc - 1; i >= 0; i--)
-		memset(argv[i], 0, strlen(argv[i]));
-	sprintf(argv[0], "para_server (serving %s)",
-		inet_ntoa(their_addr.sin_addr));
-	return handle_connect(new_fd, &their_addr);
+	exit(EXIT_SUCCESS);
 }