/*      $NetBSD: nfsd.c,v 1.74 2021/11/27 22:30:25 rillig Exp $ */

/*
 * Copyright (c) 1989, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Rick Macklem at The University of Guelph.
 *
 * 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1989, 1993, 1994\
 The Regents of the University of California.  All rights reserved.");
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)nfsd.c      8.9 (Berkeley) 3/29/95";
#else
__RCSID("$NetBSD: nfsd.c,v 1.74 2021/11/27 22:30:25 rillig Exp $");
#endif
#endif /* not lint */

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

#include <rpc/rpc.h>
#include <rpc/pmap_clnt.h>
#include <rpc/pmap_prot.h>

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

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

#ifdef NFSD_RUMP
#include <rump/rump.h>
#include <rump/rump_syscallshotgun.h>
#include <rump/rump_syscalls.h>

#define nfssvc(a, b) rump_sys_nfssvc((a), (b))
#define close(a)        rump_sys_close(a)
#define poll(a, b, c) rump_sys_poll((a), (b), (c))
#if 0
#define socket(a, b, c) rump_sys_socket((a), (b), (c))
#define setsockopt(a, b, c, d, e) rump_sys_setsockopt((a), (b), (c), (d), (e))
#define bind(a, b, c) rump_sys_bind((a), (b), (c))
#define listen(a, b) rump_sys_listen((a), (b))
#define accept(a, b, c) rump_sys_accept((a), (b), (c))
#endif
#define main nfsd_main
int nfsd_main(int, char *[]);
#endif

/* Global defs */
#if defined(DEBUG) || defined(NFSD_RUMP)
static int      debug = 1;
#else
static int      debug = 0;
#endif

#define logit(e, s, args...)                                            \
do {                                                                    \
        if (debug) {                                                    \
                fprintf(stderr,(s), ## args);                           \
                fprintf(stderr, "\n");                                  \
        } else {                                                        \
                syslog(e, s, ## args);                                  \
        }                                                               \
} while (0)

static void     nonfs(int);
__dead static void      usage(void);

static void *
worker(void *dummy)
{
        struct  nfsd_srvargs nsd;
        int nfssvc_flag;

        pthread_setname_np(pthread_self(), "slave", NULL);
        nfssvc_flag = NFSSVC_NFSD;
        memset(&nsd, 0, sizeof(nsd));
        while (nfssvc(nfssvc_flag, &nsd) == -1) {
                if (errno != ENEEDAUTH) {
                        logit(LOG_ERR, "nfssvc: %s", strerror(errno));
                        exit(EXIT_FAILURE);
                }
                nfssvc_flag = NFSSVC_NFSD | NFSSVC_AUTHINFAIL;
        }

        return NULL;
}

struct conf {
        struct addrinfo *ai;
        struct netconfig *nc;
        struct netbuf nb;
        struct pollfd pfd;
};

#define NFS_UDP4        0
#define NFS_TCP4        1
#define NFS_UDP6        2
#define NFS_TCP6        3

static int cfg_family[] = { PF_INET, PF_INET, PF_INET6, PF_INET6 };
static const char *cfg_netconf[] = { "udp", "tcp", "udp6", "tcp6" };
static int cfg_socktype[] = {
    SOCK_DGRAM, SOCK_STREAM, SOCK_DGRAM, SOCK_STREAM };
static int cfg_protocol[] = {
    IPPROTO_UDP, IPPROTO_TCP, IPPROTO_UDP, IPPROTO_TCP };

static int
tryconf(struct conf *cfg, int t, int reregister)
{
        struct addrinfo hints;
        int ecode;

        memset(&hints, 0, sizeof hints);
        hints.ai_flags = AI_PASSIVE;
        hints.ai_family = cfg_family[t];
        hints.ai_socktype = cfg_socktype[t];
        hints.ai_protocol = cfg_protocol[t];

        ecode = getaddrinfo(NULL, "nfs", &hints, &cfg->ai);
        if (ecode != 0) {
                logit(LOG_ERR, "getaddrinfo %s: %s", cfg_netconf[t],
                    gai_strerror(ecode));
                return -1;
        }

        cfg->nc = getnetconfigent(cfg_netconf[t]);

        if (cfg->nc == NULL) {
                logit(LOG_ERR, "getnetconfigent %s failed: %s",
                    cfg_netconf[t], strerror(errno));
                goto out;
        }

        cfg->nb.buf = cfg->ai->ai_addr;
        cfg->nb.len = cfg->nb.maxlen = cfg->ai->ai_addrlen;
        if (reregister)
                if (!rpcb_set(RPCPROG_NFS, 2, cfg->nc, &cfg->nb)) {
                        logit(LOG_ERR, "rpcb_set %s failed", cfg_netconf[t]);
                        goto out1;
                }
        return 0;
out1:
        freenetconfigent(cfg->nc);
        cfg->nc = NULL;
out:
        freeaddrinfo(cfg->ai);
        cfg->ai = NULL;
        return -1;
}

static int
setupsock(struct conf *cfg, struct pollfd *set, int p)
{
        int sock;
        struct nfsd_args nfsdargs;
        struct addrinfo *ai = cfg->ai;
        int on = 1;

        sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);

        if (sock == -1) {
                logit(LOG_ERR, "can't create %s socket: %s", cfg_netconf[p],
                    strerror(errno));
                return -1;
        }
        if (cfg_family[p] == PF_INET6) {
                if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on,
                    sizeof(on)) == -1) {
                        logit(LOG_ERR, "can't set v6-only binding for %s "
                            "socket: %s", cfg_netconf[p], strerror(errno));
                        goto out;
                }
        }

        if (cfg_protocol[p] == IPPROTO_TCP) {
                if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on,
                    sizeof(on)) == -1) {
                        logit(LOG_ERR, "setsockopt SO_REUSEADDR for %s: %s",
                            cfg_netconf[p], strerror(errno));
                        goto out;
                }
        }

        if (bind(sock, ai->ai_addr, ai->ai_addrlen) == -1) {
                logit(LOG_ERR, "can't bind %s addr: %s", cfg_netconf[p],
                    strerror(errno));
                goto out;
        }

        if (cfg_protocol[p] == IPPROTO_TCP) {
                if (listen(sock, 5) == -1) {
                        logit(LOG_ERR, "listen failed");
                        goto out;
                }
        }

        if (!rpcb_set(RPCPROG_NFS, 2, cfg->nc, &cfg->nb) ||
            !rpcb_set(RPCPROG_NFS, 3, cfg->nc, &cfg->nb)) {
                logit(LOG_ERR, "can't register with %s portmap",
                    cfg_netconf[p]);
                goto out;
        }


        if (cfg_protocol[p] == IPPROTO_TCP)
                set->fd = sock;
        else {
                nfsdargs.sock = sock;
                nfsdargs.name = NULL;
                nfsdargs.namelen = 0;
                if (nfssvc(NFSSVC_ADDSOCK, &nfsdargs) == -1) {
                        logit(LOG_ERR, "can't add %s socket: %s",
                            cfg_netconf[p], strerror(errno));
                        goto out;
                }
                (void)close(sock);
        }
        return 0;
out:
        (void)close(sock);
        return -1;
}

/*
 * The functions daemon2_fork() and daemon2_detach() below provide
 * functionality similar to daemon(3) but split into two phases.
 * daemon2_fork() is called early, before creating resources that
 * cannot be inherited across a fork, such as threads or kqueues.
 * When the daemon is ready to provide service, daemon2_detach()
 * is called to complete the daemonization and signal the parent
 * process to exit.
 *
 * These functions could potentially be moved to a library and
 * shared by other daemons.
 *
 * The return value from daemon2_fork() is a file descriptor to
 * be passed as the first argument to daemon2_detach().
 */

static int
daemon2_fork(void)
{
         int i;
         int fd;
         int r;
         pid_t pid;
         int detach_msg_pipe[2];

         /*
          * Set up a pipe for signalling the parent, making sure the
          * write end does not get allocated one of the file
          * descriptors that may be closed in daemon2_detach().  The
          * read end does not need such protection.
          */
         for (i = 0; i < 3; i++) {
                 r = pipe2(detach_msg_pipe, O_CLOEXEC|O_NOSIGPIPE);
                 if (r == -1)
                         return -1;
                 if (detach_msg_pipe[1] <= STDERR_FILENO &&
                     (fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
                         (void)dup2(fd, detach_msg_pipe[0]);
                         (void)dup2(fd, detach_msg_pipe[1]);
                         if (fd > STDERR_FILENO)
                                 (void)close(fd);
                         continue;
                 }
                 break;
         }

         pid = fork();
         switch (pid) {
         case -1:
                return -1;
         case 0:
                /* child */
                (void)close(detach_msg_pipe[0]);
                return detach_msg_pipe[1];
         default:
                break;
        }

        /* Parent */
        (void)close(detach_msg_pipe[1]);

        for (;;) {
                ssize_t nread;
                char dummy;
                nread = read(detach_msg_pipe[0], &dummy, 1);
                if (nread == -1) {
                        if (errno == EINTR)
                                continue;
                        _exit(EXIT_FAILURE);
                } else if (nread == 0) {
                        _exit(EXIT_FAILURE);
                } else { /* nread > 0 */
                        _exit(EXIT_SUCCESS);
                }
        }
}

static int
daemon2_detach(int parentfd, int nochdir, int noclose)
{
        int fd;

        if (setsid() == -1)
                return -1;

        if (!nochdir)
                (void)chdir("/");

        if (!noclose && (fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
                (void)dup2(fd, STDIN_FILENO);
                (void)dup2(fd, STDOUT_FILENO);
                (void)dup2(fd, STDERR_FILENO);
                if (fd > STDERR_FILENO)
                        (void)close(fd);
        }

        while (1) {
                ssize_t r = write(parentfd, "", 1);
                if (r == -1) {
                        if (errno == EINTR)
                                continue;
                        else if (errno == EPIPE)
                                break;
                        else
                                return -1;
                } else if (r == 0) {
                        /* Should not happen */
                        return -1;
                } else {
                        break;
                }
        }

        (void)close(parentfd);

        return 0;
}

/*
 * Nfs server daemon mostly just a user context for nfssvc()
 *
 * 1 - do file descriptor and signal cleanup
 * 2 - create the nfsd thread(s)
 * 3 - create server socket(s)
 * 4 - register socket with portmap
 *
 * 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().
 * The arguments are:
 *      -r - reregister with portmapper
 *      -t - support only tcp nfs clients
 *      -u - support only udp nfs clients
 *      -n num how many threads to create.
 *      -4 - use only ipv4
 *      -6 - use only ipv6
 */
int
main(int argc, char *argv[])
{
        struct conf cfg[4];
        struct pollfd set[__arraycount(cfg)];
        int ch, connect_type_cnt;
        size_t i, nfsdcnt;
        int reregister;
        int tcpflag, udpflag;
        int ip6flag, ip4flag;
        int s, compat;
        int parent_fd = -1;
        pthread_t *workers;

#define DEFNFSDCNT       4
        nfsdcnt = DEFNFSDCNT;
        compat = reregister = 0;
        tcpflag = udpflag = 1;
        ip6flag = ip4flag = 1;
#define GETOPT  "46dn:rtu"
#define USAGE   "[-46drtu] [-n num_servers]"
        while ((ch = getopt(argc, argv, GETOPT)) != -1) {
                switch (ch) {
                case '6':
                        ip6flag = 1;
                        ip4flag = 0;
                        s = socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP);
                        if (s == -1 && (errno == EPROTONOSUPPORT ||
                            errno == EPFNOSUPPORT || errno == EAFNOSUPPORT))
                                ip6flag = 0;
                        else
                                close(s);
                        break;
                case '4':
                        ip6flag = 0;
                        ip4flag = 1;
                        s = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
                        if (s == -1 && (errno == EPROTONOSUPPORT ||
                            errno == EPFNOSUPPORT || errno == EAFNOSUPPORT))
                                ip4flag = 0;
                        else
                                close(s);
                        break;
                case 'd':
                        debug++;
                        break;
                case 'n':
                        nfsdcnt = atoi(optarg);
                        if (nfsdcnt < 1) {
                                warnx("nfsd count %zu; reset to %d", nfsdcnt,
                                    DEFNFSDCNT);
                                nfsdcnt = DEFNFSDCNT;
                        }
                        break;
                case 'r':
                        reregister = 1;
                        break;
                case 't':
                        compat |= 2;
                        tcpflag = 1;
                        udpflag = 0;
                        break;
                case 'u':
                        compat |= 1;
                        tcpflag = 0;
                        udpflag = 1;
                        break;
                default:
                case '?':
                        usage();
                }
        }
        argv += optind;
        argc -= optind;

        if (compat == 3) {
                warnx("Old -tu options detected; enabling both udp and tcp.");
                warnx("This is the default behavior now and you can remove");
                warnx("all options.");
                tcpflag = udpflag = 1;
                if (ip6flag == 1 && ip4flag == 0)
                        ip4flag = 1;
        }

        if (debug == 0) {
                parent_fd = daemon2_fork();
                if (parent_fd == -1)
                        logit(LOG_ERR, "daemon2_fork failed");
                openlog("nfsd", LOG_PID, LOG_DAEMON);
        }


        memset(cfg, 0, sizeof(cfg));
        for (i = 0; i < __arraycount(cfg); i++) {
                if (ip4flag == 0 && cfg_family[i] == PF_INET)
                        continue;
                if (ip6flag == 0 && cfg_family[i] == PF_INET6)
                        continue;
                if (tcpflag == 0 && cfg_protocol[i] == IPPROTO_TCP)
                        continue;
                if (udpflag == 0 && cfg_protocol[i] == IPPROTO_UDP)
                        continue;
                tryconf(&cfg[i], i, reregister);
        }

        workers = calloc(nfsdcnt, sizeof(*workers));
        if (workers == NULL) {
                logit(LOG_ERR, "thread alloc %s", strerror(errno));
                exit(EXIT_FAILURE);
        }

        for (i = 0; i < nfsdcnt; i++) {
                int error;

                error = pthread_create(&workers[i], NULL, worker, NULL);
                if (error) {
                        errno = error;
                        logit(LOG_ERR, "pthread_create: %s", strerror(errno));
                        exit(EXIT_FAILURE);
                }
        }

        connect_type_cnt = 0;
        for (i = 0; i < __arraycount(cfg); i++) {
                set[i].fd = -1;
                set[i].events = POLLIN;
                set[i].revents = 0;

                if (cfg[i].nc == NULL)
                        continue;

                setupsock(&cfg[i], &set[i], i);
                if (set[i].fd != -1)
                        connect_type_cnt++;
        }

        pthread_setname_np(pthread_self(), "master", NULL);

        if (debug == 0) {
                daemon2_detach(parent_fd, 0, 0);
                (void)signal(SIGHUP, SIG_IGN);
                (void)signal(SIGINT, SIG_IGN);
                (void)signal(SIGQUIT, SIG_IGN);
                (void)signal(SIGSYS, nonfs);
        }

        if (connect_type_cnt == 0) {
                for (i = 0; i < nfsdcnt; i++)
                            pthread_join(workers[i], NULL);
                exit(EXIT_SUCCESS);
        }

        /*
         * Loop forever accepting connections and passing the sockets
         * into the kernel for the mounts.
         */
        for (;;) {
                if (poll(set, __arraycount(set), INFTIM) == -1) {
                        logit(LOG_ERR, "poll failed: %s", strerror(errno));
                        exit(EXIT_FAILURE);
                }

                for (i = 0; i < __arraycount(set); i++) {
                        struct nfsd_args nfsdargs;
                        struct sockaddr_storage ss;
                        socklen_t len;
                        int msgsock;
                        int on = 1;

                        if ((set[i].revents & POLLIN) == 0)
                                continue;
                        len = sizeof(ss);
                        if ((msgsock = accept(set[i].fd,
                            (struct sockaddr *)&ss, &len)) == -1) {
                                int serrno = errno;
                                logit(LOG_ERR, "accept failed: %s",
                                    strerror(errno));
                                if (serrno == EINTR || serrno == ECONNABORTED)
                                        continue;
                                exit(EXIT_FAILURE);
                        }
                        if (setsockopt(msgsock, SOL_SOCKET, SO_KEEPALIVE, &on,
                            sizeof(on)) == -1)
                                logit(LOG_ERR, "setsockopt SO_KEEPALIVE: %s",
                                    strerror(errno));
                        nfsdargs.sock = msgsock;
                        nfsdargs.name = (void *)&ss;
                        nfsdargs.namelen = len;
                        nfssvc(NFSSVC_ADDSOCK, &nfsdargs);
                        (void)close(msgsock);
                }
        }
}

static void
usage(void)
{
        (void)fprintf(stderr, "Usage: %s %s\n", getprogname(), USAGE);
        exit(EXIT_FAILURE);
}

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