/*-
 * Copyright (c) 2009 Rick Macklem, University of Guelph
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/linker.h>
#include <sys/module.h>
#include <sys/mount.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/stat.h>
#include <sys/ucred.h>
#include <sys/uio.h>
#include <sys/vnode.h>
#include <sys/wait.h>

#include <nfs/nfssvc.h>

#include <rpc/rpc.h>

#include <fs/nfs/rpcv2.h>
#include <fs/nfs/nfsproto.h>
#include <fs/nfs/nfskpiport.h>
#include <fs/nfs/nfs.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <netdb.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

/* Global defs */
#ifdef DEBUG
#define syslog(e, s)    fprintf(stderr,(s))
static int      debug = 1;
#else
static int      debug = 0;
#endif

static pid_t    children;

static void     nonfs(int);
static void     reapchild(int);
static void     usage(void);
static void     cleanup(int);
static void     child_cleanup(int);
static void     nfscbd_exit(int);
static void     killchildren(void);

/*
 * Nfs callback server daemon.
 *
 * 1 - do file descriptor and signal cleanup
 * 2 - fork the nfscbd(s)
 * 4 - create callback server socket(s)
 * 5 - set up server socket for rpc
 *
 * For connectionless protocols, just pass the socket into the kernel via.
 * nfssvc().
 * For connection based sockets, loop doing accepts. When you get a new
 * socket from accept, pass the msgsock into the kernel via. nfssvc().
 */
int
main(int argc, char *argv[])
{
        struct nfscbd_args nfscbdargs;
        struct nfsd_nfscbd_args nfscbdargs2;
        struct sockaddr_in inetaddr, inetpeer;
        fd_set ready, sockbits;
        int ch, connect_type_cnt, maxsock, msgsock, error;
        int nfssvc_flag, on, sock, tcpsock, ret, mustfreeai = 0;
        char *cp, princname[128];
        char myname[MAXHOSTNAMELEN], *myfqdnname = NULL;
        struct addrinfo *aip, hints;
        pid_t pid;
        short myport = NFSV4_CBPORT;
        socklen_t len;

        if (modfind("nfscl") < 0) {
                /* Not present in kernel, try loading it */
                if (kldload("nfscl") < 0 ||
                    modfind("nfscl") < 0)
                        errx(1, "nfscl is not available");
        }
        /*
         * First, get our fully qualified host name, if possible.
         */
        if (gethostname(myname, MAXHOSTNAMELEN) >= 0) {
                cp = strchr(myname, '.');
                if (cp != NULL && *(cp + 1) != '\0') {
                        cp = myname;
                } else {
                        /*
                         * No domain on myname, so try looking it up.
                         */
                        cp = NULL;
                        memset((void *)&hints, 0, sizeof (hints));
                        hints.ai_flags = AI_CANONNAME;
                        error = getaddrinfo(myname, NULL, &hints, &aip);
                        if (error == 0) {
                            if (aip->ai_canonname != NULL &&
                                (cp = strchr(aip->ai_canonname, '.')) != NULL
                                && *(cp + 1) != '\0') {
                                    cp = aip->ai_canonname;
                                    mustfreeai = 1;
                            } else {
                                    freeaddrinfo(aip);
                            }
                        }
                }
                if (cp == NULL)
                        warnx("Can't get fully qualified host name");
                myfqdnname = cp;
        }

        princname[0] = '\0';
#define GETOPT  "p:P:"
#define USAGE   "[ -p port_num ] [ -P client_principal ]"
        while ((ch = getopt(argc, argv, GETOPT)) != -1)
                switch (ch) {
                case 'p':
                        myport = atoi(optarg);
                        if (myport < 1) {
                                warnx("port# non-positive, reset to %d",
                                    NFSV4_CBPORT);
                                myport = NFSV4_CBPORT;
                        }
                        break;
                case 'P':
                        cp = optarg;
                        if (cp != NULL && strlen(cp) > 0 &&
                            strlen(cp) < sizeof (princname)) {
                                if (strchr(cp, '@') == NULL &&
                                    myfqdnname != NULL)
                                        snprintf(princname, sizeof (princname),
                                            "%s@%s", cp, myfqdnname);
                                else
                                        strlcpy(princname, cp,
                                            sizeof (princname));
                        } else {
                                warnx("client princ invalid. ignored\n");
                        }
                        break;
                default:
                case '?':
                        usage();
                }
        argv += optind;
        argc -= optind;

        if (argc > 0)
                usage();

        if (mustfreeai)
                freeaddrinfo(aip);
        nfscbdargs2.principal = (const char *)princname;
        if (debug == 0) {
                daemon(0, 0);
                (void)signal(SIGTERM, SIG_IGN);
                (void)signal(SIGHUP, SIG_IGN);
                (void)signal(SIGINT, SIG_IGN);
                (void)signal(SIGQUIT, SIG_IGN);
        }
        (void)signal(SIGSYS, nonfs);
        (void)signal(SIGCHLD, reapchild);

        openlog("nfscbd:", LOG_PID, LOG_DAEMON);

        pid = fork();
        if (pid < 0) {
                syslog(LOG_ERR, "fork: %m");
                nfscbd_exit(1);
        } else if (pid > 0) {
                children = pid;
        } else {
                (void)signal(SIGUSR1, child_cleanup);
                setproctitle("server");
                nfssvc_flag = NFSSVC_NFSCBD;
                if (nfssvc(nfssvc_flag, &nfscbdargs2) < 0) {
                        syslog(LOG_ERR, "nfssvc: %m");
                        nfscbd_exit(1);
                }
                exit(0);
        }
        (void)signal(SIGUSR1, cleanup);

        if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
                syslog(LOG_ERR, "can't create udp socket");
                nfscbd_exit(1);
        }
        memset(&inetaddr, 0, sizeof inetaddr);
        inetaddr.sin_family = AF_INET;
        inetaddr.sin_addr.s_addr = INADDR_ANY;
        inetaddr.sin_port = htons(myport);
        inetaddr.sin_len = sizeof(inetaddr);
        ret = bind(sock, (struct sockaddr *)&inetaddr, sizeof(inetaddr));
        /* If bind() fails, this is a restart, so just skip UDP. */
        if (ret == 0) {
                len = sizeof(inetaddr);
                if (getsockname(sock, (struct sockaddr *)&inetaddr, &len) < 0){
                        syslog(LOG_ERR, "can't get bound addr");
                        nfscbd_exit(1);
                }
                nfscbdargs.port = ntohs(inetaddr.sin_port);
                if (nfscbdargs.port != myport) {
                        syslog(LOG_ERR, "BAD PORT#");
                        nfscbd_exit(1);
                }
                nfscbdargs.sock = sock;
                nfscbdargs.name = NULL;
                nfscbdargs.namelen = 0;
                if (nfssvc(NFSSVC_CBADDSOCK, &nfscbdargs) < 0) {
                        syslog(LOG_ERR, "can't Add UDP socket");
                        nfscbd_exit(1);
                }
        }
        (void)close(sock);

        /* Now set up the master server socket waiting for tcp connections. */
        on = 1;
        FD_ZERO(&sockbits);
        connect_type_cnt = 0;
        if ((tcpsock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
                syslog(LOG_ERR, "can't create tcp socket");
                nfscbd_exit(1);
        }
        if (setsockopt(tcpsock,
            SOL_SOCKET, SO_REUSEADDR, (char *)&on, sizeof(on)) < 0)
                syslog(LOG_ERR, "setsockopt SO_REUSEADDR: %m");
        /* sin_port is already set */
        inetaddr.sin_family = AF_INET;
        inetaddr.sin_addr.s_addr = INADDR_ANY;
        inetaddr.sin_port = htons(myport);
        inetaddr.sin_len = sizeof(inetaddr);
        if (bind(tcpsock,
            (struct sockaddr *)&inetaddr, sizeof (inetaddr)) < 0) {
                syslog(LOG_ERR, "can't bind tcp addr");
                nfscbd_exit(1);
        }
        if (listen(tcpsock, 5) < 0) {
                syslog(LOG_ERR, "listen failed");
                nfscbd_exit(1);
        }
        FD_SET(tcpsock, &sockbits);
        maxsock = tcpsock;
        connect_type_cnt++;

        setproctitle("master");

        /*
         * Loop forever accepting connections and passing the sockets
         * into the kernel for the mounts.
         */
        for (;;) {
                ready = sockbits;
                if (connect_type_cnt > 1) {
                        if (select(maxsock + 1,
                            &ready, NULL, NULL, NULL) < 1) {
                                syslog(LOG_ERR, "select failed: %m");
                                nfscbd_exit(1);
                        }
                }
                if (FD_ISSET(tcpsock, &ready)) {
                        len = sizeof(inetpeer);
                        if ((msgsock = accept(tcpsock,
                            (struct sockaddr *)&inetpeer, &len)) < 0) {
                                syslog(LOG_ERR, "accept failed: %m");
                                nfscbd_exit(1);
                        }
                        memset(inetpeer.sin_zero, 0,
                            sizeof (inetpeer.sin_zero));
                        if (setsockopt(msgsock, SOL_SOCKET,
                            SO_KEEPALIVE, (char *)&on, sizeof(on)) < 0)
                                syslog(LOG_ERR,
                                    "setsockopt SO_KEEPALIVE: %m");
                        nfscbdargs.sock = msgsock;
                        nfscbdargs.name = (caddr_t)&inetpeer;
                        nfscbdargs.namelen = sizeof(inetpeer);
                        nfssvc(NFSSVC_CBADDSOCK, &nfscbdargs);
                        (void)close(msgsock);
                }
        }
}

static void
usage(void)
{

        errx(1, "usage: nfscbd %s", USAGE);
}

static void
nonfs(int signo __unused)
{
        syslog(LOG_ERR, "missing system call: NFS not available");
}

static void
reapchild(int signo __unused)
{
        pid_t pid;

        while ((pid = wait3(NULL, WNOHANG, NULL)) > 0) {
                if (pid == children)
                        children = -1;
        }
}

static void
killchildren(void)
{

        if (children > 0)
                kill(children, SIGKILL);
}

/*
 * Cleanup master after SIGUSR1.
 */
static void
cleanup(int signo __unused)
{
        nfscbd_exit(0);
}

/*
 * Cleanup child after SIGUSR1.
 */
static void
child_cleanup(int signo __unused)
{
        exit(0);
}

static void
nfscbd_exit(int status __unused)
{
        killchildren();
        exit(status);
}