/*
 * Copyright (c) 1990,1993 Regents of The University of Michigan.
 * All Rights Reserved.  See COPYRIGHT.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif /* HAVE_CONFIG_H */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <sys/param.h>
#include <sys/uio.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/poll.h>
#include <errno.h>
#include <sys/wait.h>
#include <sys/resource.h>

#include <atalk/logger.h>
#include <atalk/adouble.h>
#include <atalk/compat.h>
#include <atalk/dsi.h>
#include <atalk/afp.h>
#include <atalk/paths.h>
#include <atalk/util.h>
#include <atalk/server_child.h>
#include <atalk/server_ipc.h>
#include <atalk/errchk.h>
#include <atalk/globals.h>
#include <atalk/netatalk_conf.h>

#include "afp_config.h"
#include "status.h"
#include "fork.h"
#include "uam_auth.h"
#include "afp_zeroconf.h"

#define AFP_LISTENERS 32
#define FDSET_SAFETY  5

unsigned char nologin = 0;

static AFPObj obj;
static server_child *server_children;
static sig_atomic_t reloadconfig = 0;
static sig_atomic_t gotsigchld = 0;

/* Two pointers to dynamic allocated arrays which store pollfds and associated data */
static struct pollfd *fdset;
static struct polldata *polldata;
static int fdset_size;          /* current allocated size */
static int fdset_used;          /* number of used elements */
static int disasociated_ipc_fd; /* disasociated sessions uses this fd for IPC */

static afp_child_t *dsi_start(AFPObj *obj, DSI *dsi, server_child *server_children);

static void afp_exit(int ret)
{
    exit(ret);
}


/* ------------------
   initialize fd set we are waiting for.
*/
static void fd_set_listening_sockets(const AFPObj *config)
{
    DSI *dsi;

    for (dsi = config->dsi; dsi; dsi = dsi->next) {
        fdset_add_fd(config->options.connections + AFP_LISTENERS + FDSET_SAFETY,
                     &fdset,
                     &polldata,
                     &fdset_used,
                     &fdset_size,
                     dsi->serversock,
                     LISTEN_FD,
                     dsi);
    }

    if (config->options.flags & OPTION_KEEPSESSIONS)
        fdset_add_fd(config->options.connections + AFP_LISTENERS + FDSET_SAFETY,
                     &fdset,
                     &polldata,
                     &fdset_used,
                     &fdset_size,
                     disasociated_ipc_fd,
                     DISASOCIATED_IPC_FD,
                     NULL);
}
 
static void fd_reset_listening_sockets(const AFPObj *config)
{
    const DSI *dsi;

    for (dsi = config->dsi; dsi; dsi = dsi->next) {
        fdset_del_fd(&fdset, &polldata, &fdset_used, &fdset_size, dsi->serversock);
    }

    if (config->options.flags & OPTION_KEEPSESSIONS)
        fdset_del_fd(&fdset, &polldata, &fdset_used, &fdset_size, disasociated_ipc_fd);
}

/* ------------------ */
static void afp_goaway(int sig)
{
    switch( sig ) {

    case SIGTERM:
    case SIGQUIT:
        switch (sig) {
        case SIGTERM:
            LOG(log_note, logtype_afpd, "AFP Server shutting down on SIGTERM");
            break;
        case SIGQUIT:
            if (obj.options.flags & OPTION_KEEPSESSIONS) {
                LOG(log_note, logtype_afpd, "AFP Server shutting down on SIGQUIT, NOT disconnecting clients");
            } else {
                LOG(log_note, logtype_afpd, "AFP Server shutting down on SIGQUIT");
                sig = SIGTERM;
            }
            break;
        }
        if (server_children)
            server_child_kill(server_children, CHILD_DSIFORK, sig);

        _exit(0);
        break;

    case SIGUSR1 :
        nologin++;
        auth_unload();
        LOG(log_info, logtype_afpd, "disallowing logins");        

        if (server_children)
            server_child_kill(server_children, CHILD_DSIFORK, sig);
        break;

    case SIGHUP :
        /* w/ a configuration file, we can force a re-read if we want */
        reloadconfig = 1;
        break;

    case SIGCHLD:
        /* w/ a configuration file, we can force a re-read if we want */
        gotsigchld = 1;
        break;

    default :
        LOG(log_error, logtype_afpd, "afp_goaway: bad signal" );
    }
    return;
}

static void child_handler(void)
{
    int fd;
    int status, i;
    pid_t pid;
  
#ifndef WAIT_ANY
#define WAIT_ANY (-1)
#endif /* ! WAIT_ANY */

    while ((pid = waitpid(WAIT_ANY, &status, WNOHANG)) > 0) {
        for (i = 0; i < server_children->nforks; i++) {
            if ((fd = server_child_remove(server_children, i, pid)) != -1) {
                fdset_del_fd(&fdset, &polldata, &fdset_used, &fdset_size, fd);        
                break;
            }
        }

        if (WIFEXITED(status)) {
            if (WEXITSTATUS(status))
                LOG(log_info, logtype_afpd, "child[%d]: exited %d", pid, WEXITSTATUS(status));
            else
                LOG(log_info, logtype_afpd, "child[%d]: done", pid);
        } else {
            if (WIFSIGNALED(status))
                LOG(log_info, logtype_afpd, "child[%d]: killed by signal %d", pid, WTERMSIG(status));
            else
                LOG(log_info, logtype_afpd, "child[%d]: died", pid);
        }
    }
}

static int setlimits(void)
{
    struct rlimit rlim;

    if (getrlimit(RLIMIT_NOFILE, &rlim) != 0) {
        LOG(log_warning, logtype_afpd, "setlimits: reading current limits failed: %s", strerror(errno));
        return -1;
    }
    if (rlim.rlim_cur != RLIM_INFINITY && rlim.rlim_cur < 65535) {
        rlim.rlim_cur = 65535;
        if (rlim.rlim_max != RLIM_INFINITY && rlim.rlim_max < 65535)
            rlim.rlim_max = 65535;
        if (setrlimit(RLIMIT_NOFILE, &rlim) != 0) {
            LOG(log_warning, logtype_afpd, "setlimits: increasing limits failed: %s", strerror(errno));
            return -1;
        }
    }
    return 0;
}

int main(int ac, char **av)
{
    fd_set              rfds;
    void                *ipc;
    struct sigaction	sv;
    sigset_t            sigs;
    int                 ret;

    /* Parse argv args and initialize default options */
    afp_options_parse_cmdline(&obj, ac, av);

    if (!(obj.cmdlineflags & OPTION_DEBUG) && (daemonize(0, 0) != 0))
        exit(EXITERR_SYS);

    /* Log SIGBUS/SIGSEGV SBT */
    fault_setup(NULL);

    if (afp_config_parse(&obj, "afpd") != 0)
        afp_exit(EXITERR_CONF);

    /* Save the user's current umask */
    obj.options.save_mask = umask(obj.options.umask);

    /* install child handler for asp and dsi. we do this before afp_goaway
     * as afp_goaway references stuff from here. 
     * XXX: this should really be setup after the initial connections. */
    if (!(server_children = server_child_alloc(obj.options.connections, CHILD_NFORKS))) {
        LOG(log_error, logtype_afpd, "main: server_child alloc: %s", strerror(errno) );
        afp_exit(EXITERR_SYS);
    }
    
    sigemptyset(&sigs);
    pthread_sigmask(SIG_SETMASK, &sigs, NULL);

    memset(&sv, 0, sizeof(sv));    
    /* linux at least up to 2.4.22 send a SIGXFZ for vfat fs,
       even if the file is open with O_LARGEFILE ! */
#ifdef SIGXFSZ
    sv.sa_handler = SIG_IGN;
    sigemptyset( &sv.sa_mask );
    if (sigaction(SIGXFSZ, &sv, NULL ) < 0 ) {
        LOG(log_error, logtype_afpd, "main: sigaction: %s", strerror(errno) );
        afp_exit(EXITERR_SYS);
    }
#endif
    
    sv.sa_handler = afp_goaway; /* handler for all sigs */

    sigemptyset( &sv.sa_mask );
    sigaddset(&sv.sa_mask, SIGALRM);
    sigaddset(&sv.sa_mask, SIGHUP);
    sigaddset(&sv.sa_mask, SIGTERM);
    sigaddset(&sv.sa_mask, SIGUSR1);
    sigaddset(&sv.sa_mask, SIGQUIT);    
    sv.sa_flags = SA_RESTART;
    if ( sigaction( SIGCHLD, &sv, NULL ) < 0 ) {
        LOG(log_error, logtype_afpd, "main: sigaction: %s", strerror(errno) );
        afp_exit(EXITERR_SYS);
    }

    sigemptyset( &sv.sa_mask );
    sigaddset(&sv.sa_mask, SIGALRM);
    sigaddset(&sv.sa_mask, SIGTERM);
    sigaddset(&sv.sa_mask, SIGHUP);
    sigaddset(&sv.sa_mask, SIGCHLD);
    sigaddset(&sv.sa_mask, SIGQUIT);
    sv.sa_flags = SA_RESTART;
    if ( sigaction( SIGUSR1, &sv, NULL ) < 0 ) {
        LOG(log_error, logtype_afpd, "main: sigaction: %s", strerror(errno) );
        afp_exit(EXITERR_SYS);
    }

    sigemptyset( &sv.sa_mask );
    sigaddset(&sv.sa_mask, SIGALRM);
    sigaddset(&sv.sa_mask, SIGTERM);
    sigaddset(&sv.sa_mask, SIGUSR1);
    sigaddset(&sv.sa_mask, SIGCHLD);
    sigaddset(&sv.sa_mask, SIGQUIT);
    sv.sa_flags = SA_RESTART;
    if ( sigaction( SIGHUP, &sv, NULL ) < 0 ) {
        LOG(log_error, logtype_afpd, "main: sigaction: %s", strerror(errno) );
        afp_exit(EXITERR_SYS);
    }

    sigemptyset( &sv.sa_mask );
    sigaddset(&sv.sa_mask, SIGALRM);
    sigaddset(&sv.sa_mask, SIGHUP);
    sigaddset(&sv.sa_mask, SIGUSR1);
    sigaddset(&sv.sa_mask, SIGCHLD);
    sigaddset(&sv.sa_mask, SIGQUIT);
    sv.sa_flags = SA_RESTART;
    if ( sigaction( SIGTERM, &sv, NULL ) < 0 ) {
        LOG(log_error, logtype_afpd, "main: sigaction: %s", strerror(errno) );
        afp_exit(EXITERR_SYS);
    }

    sigemptyset( &sv.sa_mask );
    sigaddset(&sv.sa_mask, SIGALRM);
    sigaddset(&sv.sa_mask, SIGHUP);
    sigaddset(&sv.sa_mask, SIGUSR1);
    sigaddset(&sv.sa_mask, SIGCHLD);
    sigaddset(&sv.sa_mask, SIGTERM);
    sv.sa_flags = SA_RESTART;
    if (sigaction(SIGQUIT, &sv, NULL ) < 0 ) {
        LOG(log_error, logtype_afpd, "main: sigaction: %s", strerror(errno) );
        afp_exit(EXITERR_SYS);
    }

    /* afp.conf:  not in config file: lockfile, configfile
     *            preference: command-line provides defaults.
     *                        config file over-writes defaults.
     *
     * we also need to make sure that killing afpd during startup
     * won't leave any lingering registered names around.
     */

    sigemptyset(&sigs);
    sigaddset(&sigs, SIGALRM);
    sigaddset(&sigs, SIGHUP);
    sigaddset(&sigs, SIGUSR1);
#if 0
    /* don't block SIGTERM */
    sigaddset(&sigs, SIGTERM);
#endif
    sigaddset(&sigs, SIGCHLD);

    pthread_sigmask(SIG_BLOCK, &sigs, NULL);
    if (configinit(&obj) != 0) {
        LOG(log_error, logtype_afpd, "main: no servers configured");
        afp_exit(EXITERR_CONF);
    }
    pthread_sigmask(SIG_UNBLOCK, &sigs, NULL);

    /* Initialize */
    cnid_init();
    
    /* watch atp, dsi sockets and ipc parent/child file descriptor. */

    if (obj.options.flags & OPTION_KEEPSESSIONS) {
        LOG(log_note, logtype_afpd, "Activating continous service");
        disasociated_ipc_fd = ipc_server_uds(_PATH_AFP_IPC);
    }

    fd_set_listening_sockets(&obj);

    /* set limits */
    (void)setlimits();

    afp_child_t *child;
    int recon_ipc_fd;
    pid_t pid;
    int saveerrno;

    /* wait for an appleshare connection. parent remains in the loop
     * while the children get handled by afp_over_{asp,dsi}.  this is
     * currently vulnerable to a denial-of-service attack if a
     * connection is made without an actual login attempt being made
     * afterwards. establishing timeouts for logins is a possible 
     * solution. */
    while (1) {
        LOG(log_maxdebug, logtype_afpd, "main: polling %i fds", fdset_used);
        pthread_sigmask(SIG_UNBLOCK, &sigs, NULL);
        ret = poll(fdset, fdset_used, -1);
        pthread_sigmask(SIG_BLOCK, &sigs, NULL);
        saveerrno = errno;

        if (gotsigchld) {
            gotsigchld = 0;
            child_handler();
            continue;
        }

        if (reloadconfig) {
            nologin++;
            auth_unload();
            fd_reset_listening_sockets(&obj);

            LOG(log_info, logtype_afpd, "re-reading configuration file");

            configfree(&obj, NULL);
            if (configinit(&obj) != 0) {
                LOG(log_error, logtype_afpd, "config re-read: no servers configured");
                afp_exit(EXITERR_CONF);
            }

            fd_set_listening_sockets(&obj);

            nologin = 0;
            reloadconfig = 0;
            errno = saveerrno;
            continue;
        }

        if (ret == 0)
            continue;
        
        if (ret < 0) {
            if (errno == EINTR)
                continue;
            LOG(log_error, logtype_afpd, "main: can't wait for input: %s", strerror(errno));
            break;
        }

        for (int i = 0; i < fdset_used; i++) {
            if (fdset[i].revents & (POLLIN | POLLERR | POLLHUP | POLLNVAL)) {
                switch (polldata[i].fdtype) {

                case LISTEN_FD:
                    if (child = dsi_start(&obj, (DSI *)polldata[i].data, server_children)) {
                        /* Add IPC fd to select fd set */
                        fdset_add_fd(obj.options.connections + AFP_LISTENERS + FDSET_SAFETY,
                                     &fdset,
                                     &polldata,
                                     &fdset_used,
                                     &fdset_size,
                                     child->ipc_fd,
                                     IPC_FD,
                                     child);
                    }
                    break;

                case IPC_FD:
                    child = (afp_child_t *)polldata[i].data;
                    LOG(log_debug, logtype_afpd, "main: IPC request from child[%u]", child->pid);

                    if (ipc_server_read(server_children, child->ipc_fd) != 0) {
                        fdset_del_fd(&fdset, &polldata, &fdset_used, &fdset_size, child->ipc_fd);
                        close(child->ipc_fd);
                        child->ipc_fd = -1;
                        if ((obj.options.flags & OPTION_KEEPSESSIONS) && child->disasociated) {
                            LOG(log_note, logtype_afpd, "main: removing reattached child[%u]", child->pid);
                            server_child_remove(server_children, CHILD_DSIFORK, child->pid);
                        }
                    }
                    break;

                case DISASOCIATED_IPC_FD:
                    LOG(log_debug, logtype_afpd, "main: IPC reconnect request");
                    if ((recon_ipc_fd = accept(disasociated_ipc_fd, NULL, NULL)) == -1) {
                        LOG(log_error, logtype_afpd, "main: accept: %s", strerror(errno));
                        break;
                    }
                    if (readt(recon_ipc_fd, &pid, sizeof(pid_t), 0, 1) != sizeof(pid_t)) {
                        LOG(log_error, logtype_afpd, "main: readt: %s", strerror(errno));
                        close(recon_ipc_fd);
                        break;
                    }
                    LOG(log_note, logtype_afpd, "main: IPC reconnect from pid [%u]", pid);

                    if ((child = server_child_add(server_children, CHILD_DSIFORK, pid, recon_ipc_fd)) == NULL) {
                        LOG(log_error, logtype_afpd, "main: server_child_add");
                        close(recon_ipc_fd);
                        break;
                    }
                    child->disasociated = 1;
                    fdset_add_fd(obj.options.connections + AFP_LISTENERS + FDSET_SAFETY,
                                 &fdset,
                                 &polldata,
                                 &fdset_used,
                                 &fdset_size,
                                 recon_ipc_fd,
                                 IPC_FD,
                                 child);
                    break;

                default:
                    LOG(log_debug, logtype_afpd, "main: IPC request for unknown type");
                    break;
                } /* switch */
            }  /* if */
        } /* for (i)*/
    } /* while (1) */

    return 0;
}

static afp_child_t *dsi_start(AFPObj *obj, DSI *dsi, server_child *server_children)
{
    afp_child_t *child = NULL;

    if (dsi_getsession(dsi, server_children, obj->options.tickleval, &child) != 0) {
        LOG(log_error, logtype_afpd, "dsi_start: session error: %s", strerror(errno));
        return NULL;
    }

    /* we've forked. */
    if (child == NULL) {
        configfree(obj, dsi);
        afp_over_dsi(obj); /* start a session */
        exit (0);
    }

    return child;
}
