[paraslash.git] / server.c

/*
 * Copyright (C) 1997-2013 Andre Noll <maan@systemlinux.org>
 *
 * Licensed under the GPL v2. For licencing details see COPYING.
 */

/** \file server.c Paraslash's main server. */


/**
 * \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, \ref play.c,
 *      - Server: \ref server_command, \ref sender,
 *      - Audio file selector: \ref audio_format_handler, \ref afs_table,
 *      - Client: \ref receiver, \ref receiver_node, \ref filter,
 *        \ref filter_node, \ref writer_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, \ref wma_afh.c, \ref spx_afh.c
 *      - Decoders: \ref mp3dec_filter.c, \ref oggdec_filter.c,
 *        \ref aacdec_filter.c, \ref wmadec_filter.c, spxdec_filter.c,
 *        \ref flacdec_filter.c,
 *      - Volume normalizer: \ref compress_filter.c,
 *      - Output: \ref alsa_write.c, \ref osx_write.c, \ref oss_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 subsystem: \ref error.h.
 *      - Access control for paraslash senders: \ref acl.c, \ref acl.h.
 *      - Internal crypto API: \ref crypt.h.
 *      - interactive sessions (libreadline): \ref interactive.c.
 *
 * Low-level data structures:
 *
 *      - Doubly linked lists: \ref list.h,
 *      - Ring buffer: \ref ringbuffer.c, \ref ringbuffer.h,
 *      - openssl: \ref crypt.c
 *      - libgcrypt: \ref gcrypt.c
 *      - Forward error correction: \ref fec.c.
 */

#include <signal.h>
#include <regex.h>
#include <osl.h>

#include "para.h"
#include "error.h"
#include "crypt.h"
#include "server.cmdline.h"
#include "afh.h"
#include "string.h"
#include "afs.h"
#include "server.h"
#include "list.h"
#include "send.h"
#include "sched.h"
#include "vss.h"
#include "config.h"
#include "close_on_fork.h"
#include "net.h"
#include "daemon.h"
#include "ipc.h"
#include "fd.h"
#include "signal.h"
#include "user_list.h"
#include "color.h"
#include "version.h"

__printf_2_3 void (*para_log)(int, const char*, ...) = daemon_log;

/** Define the array of error lists needed by para_server. */
INIT_SERVER_ERRLISTS;

/** Shut down non-authorized connections after that many seconds. */
#define ALARM_TIMEOUT 10

/**
 * 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
 *
 * It also contains the options for the audio file selector, audio format
 * handler and all supported senders.
 */
struct server_args_info conf;

/** 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;

/** The file containing user information (public key, permissions). */
static char *user_list_file = NULL;

static struct sched sched;

/** 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)
{
        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 i;

        if (!want_colors())
                return;
        daemon_set_flag(DF_COLOR_LOG);
        daemon_set_default_log_colors();
        for (i = 0; i < conf.log_color_given; i++)
                daemon_set_log_color_or_die(conf.log_color_arg[i]);
}

/*
 * setup shared memory area and get mutex for locking
 */
static void init_ipc_or_die(void)
{
        void *shm;
        int shmid, ret = shm_new(sizeof(struct misc_meta_data));

        if (ret < 0)
                goto err_out;
        shmid = ret;
        ret = shm_attach(shmid, ATTACH_RW, &shm);
        shm_destroy(shmid);
        if (ret < 0)
                goto err_out;
        mmd = shm;

        ret = mutex_new();
        if (ret < 0)
                goto err_out;
        mmd_mutex = ret;

        mmd->num_played = 0;
        mmd->num_commands = 0;
        mmd->events = 0;
        mmd->num_connects = 0;
        mmd->active_connections = 0;
        mmd->vss_status_flags = VSS_NEXT;
        mmd->new_vss_status_flags = VSS_NEXT;
        return;
err_out:
        PARA_EMERG_LOG("%s\n", para_strerror(-ret));
        exit(EXIT_FAILURE);
}

/**
 * (Re-)read the server configuration files.
 *
 * \param override Passed to gengetopt to activate the override feature.
 *
 * This function also re-opens the logfile and sets the global \a
 * user_list_file variable.
 */
void parse_config_or_die(int override)
{
        char *home = para_homedir();
        int ret;
        char *cf;

        daemon_close_log();
        if (conf.config_file_given)
                cf = para_strdup(conf.config_file_arg);
        else
                cf = make_message("%s/.paraslash/server.conf", home);
        free(user_list_file);
        if (!conf.user_list_given)
                user_list_file = make_message("%s/.paraslash/server.users", home);
        else
                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 read config file %s\n", cf);
                goto out;
        }
        if (ret) {
                int tmp = conf.daemon_given;
                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;
        }
        if (conf.logfile_given) {
                daemon_set_logfile(conf.logfile_arg);
                daemon_open_log_or_die();
        }
        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);
        if (conf.log_timing_given)
                daemon_set_flag(DF_LOG_TIMING);
        ret = 1;
out:
        free(cf);
        free(home);
        if (ret > 0)
                return;
        free(user_list_file);
        user_list_file = NULL;
        exit(EXIT_FAILURE);
}

static void signal_pre_select(struct sched *s, struct task *t)
{
        struct signal_task *st = container_of(t, struct signal_task, task);
        para_fd_set(st->fd, &s->rfds, &s->max_fileno);
}

/*
 * called when server gets SIGHUP or when client invokes hup command.
 */
static void handle_sighup(void)
{
        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, __a_unused struct task *t)
{
        int signum = para_next_signal(&s->rfds);

        switch (signum) {
        case 0:
                return;
        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_EMERG_LOG("fatal: afs died\n");
                        kill(0, SIGTERM);
                        goto cleanup;
                }
                break;
        /* die on sigint/sigterm. Kill all children too. */
        case SIGINT:
        case SIGTERM:
                PARA_EMERG_LOG("terminating on signal %d\n", 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);
        }
}

static void init_signal_task(void)
{
        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(&sched, &st->task);
}

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 command_post_select(struct sched *s, struct task *t)
{
        struct server_command_task *sct = container_of(t, struct server_command_task, task);

        int new_fd, ret, i;
        char *peer_name;
        pid_t child_pid;
        uint32_t *chunk_table;

        ret = para_accept(sct->listen_fd, &s->rfds, NULL, 0, &new_fd);
        if (ret <= 0)
                goto out;
        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;
        }
        if (child_pid) {
                close(new_fd);
                /* parent keeps accepting connections */
                return;
        }
        /* 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_simple(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 */
        sprintf(sct->task.status, "server command task");
        register_task(&sched, &sct->task);
        return;
err:
        PARA_EMERG_LOG("%s\n", para_strerror(-ret));
        exit(EXIT_FAILURE);
}

static int init_afs(int argc, char **argv)
{
        int ret, afs_server_socket[2];
        pid_t afs_pid;

        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));
        afs_pid = fork();
        if (afs_pid < 0)
                exit(EXIT_FAILURE);
        if (afs_pid == 0) { /* child (afs) */
                int i;
                for (i = argc - 1; i >= 0; i--)
                        memset(argv[i], 0, strlen(argv[i]));
                sprintf(argv[0], "para_server (afs)");
                close(afs_server_socket[0]);
                afs_init(afs_socket_cookie, afs_server_socket[1]);
        }
        mmd->afs_pid = afs_pid;
        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 server_init(int argc, char **argv)
{
        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 */
        clock_get_realtime(now);
        set_server_start_time(now);
        init_user_list(user_list_file);
        /* become daemon */
        if (conf.daemon_given)
                daemonize(true /* parent waits for SIGTERM */);
        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 block SIGCHLD before the afs process is being forked off.
         * Otherwise, para_server does not notice if afs dies before the
         * SIGCHLD handler has been installed for the parent process by
         * init_signal_task() below.
         */
        para_block_signal(SIGCHLD);
        PARA_NOTICE_LOG("initializing the audio file selector\n");
        afs_socket = init_afs(argc, argv);
        init_signal_task();
        para_unblock_signal(SIGCHLD);
        PARA_NOTICE_LOG("initializing virtual streaming system\n");
        init_vss_task(afs_socket, &sched);
        init_server_command_task(argc, argv);
        if (conf.daemon_given)
                kill(getppid(), SIGTERM);
        PARA_NOTICE_LOG("server init complete\n");
}

static void status_refresh(void)
{
        static int prev_uptime = -1, prev_events = -1;
        int uptime = get_server_uptime(now);

        if (prev_events != mmd->events)
                goto out;
        if (mmd->new_vss_status_flags != mmd->vss_status_flags)
                goto out_inc_events;
        if (uptime / 60 != prev_uptime / 60)
                goto out_inc_events;
        return;
out_inc_events:
        mmd->events++;
out:
        prev_uptime = uptime;
        prev_events = mmd->events;
        mmd->vss_status_flags = mmd->new_vss_status_flags;
        PARA_DEBUG_LOG("%d events, forcing status update\n", mmd->events);
        killpg(0, SIGUSR1);
}

static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
                struct timeval *timeout_tv)
{
        int ret;

        status_refresh();
        mutex_unlock(mmd_mutex);
        ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
        mutex_lock(mmd_mutex);
        return ret;
}

/**
 * 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;

        sched.default_timeout.tv_sec = 1;
        sched.select_function = server_select;

        server_init(argc, argv);
        mutex_lock(mmd_mutex);
        ret = schedule(&sched);
        if (ret < 0) {
                PARA_EMERG_LOG("%s\n", para_strerror(-ret));
                exit(EXIT_FAILURE);
        }
        exit(EXIT_SUCCESS);
}