/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2012 The FreeBSD Foundation
 *
 * This software was developed by Edward Tomasz Napierala under sponsorship
 * from the FreeBSD Foundation.
 *
 * 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/types.h>
#include <sys/time.h>
#include <sys/ioctl.h>
#include <sys/param.h>
#include <sys/linker.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/capsicum.h>
#include <sys/wait.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <assert.h>
#include <capsicum_helpers.h>
#include <errno.h>
#include <fcntl.h>
#include <libutil.h>
#include <netdb.h>
#include <signal.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "iscsid.h"

static bool     timed_out(void);
#ifdef ICL_KERNEL_PROXY
static void     pdu_receive_proxy(struct pdu *pdu);
static void     pdu_send_proxy(struct pdu *pdu);
#endif /* ICL_KERNEL_PROXY */

static volatile bool sigalrm_received = false;

static int nchildren = 0;

static struct connection_ops conn_ops = {
        .timed_out = timed_out,
#ifdef ICL_KERNEL_PROXY
        .pdu_receive_proxy = pdu_receive_proxy,
        .pdu_send_proxy = pdu_send_proxy,
#endif
        .fail = fail,
};

static void
usage(void)
{

        fprintf(stderr, "usage: iscsid [-P pidfile][-d][-m maxproc][-t timeout]\n");
        exit(1);
}

#ifdef ICL_KERNEL_PROXY

static void
pdu_receive_proxy(struct pdu *pdu)
{
        struct iscsid_connection *conn;
        struct iscsi_daemon_receive idr;
        size_t len;
        int error;

        conn = (struct iscsid_connection *)pdu->pdu_connection;
        assert(conn->conn_conf.isc_iser != 0);

        pdu->pdu_data = malloc(conn->conn.conn_max_recv_data_segment_length);
        if (pdu->pdu_data == NULL)
                log_err(1, "malloc");

        memset(&idr, 0, sizeof(idr));
        idr.idr_session_id = conn->conn_session_id;
        idr.idr_bhs = pdu->pdu_bhs;
        idr.idr_data_segment_len = conn->conn.conn_max_recv_data_segment_length;
        idr.idr_data_segment = pdu->pdu_data;

        error = ioctl(conn->conn_iscsi_fd, ISCSIDRECEIVE, &idr);
        if (error != 0)
                log_err(1, "ISCSIDRECEIVE");

        len = pdu_ahs_length(pdu);
        if (len > 0)
                log_errx(1, "protocol error: non-empty AHS");

        len = pdu_data_segment_length(pdu);
        assert(len <= (size_t)conn->conn.conn_max_recv_data_segment_length);
        pdu->pdu_data_len = len;
}

static void
pdu_send_proxy(struct pdu *pdu)
{
        struct iscsid_connection *conn;
        struct iscsi_daemon_send ids;
        int error;

        conn = (struct iscsid_connection *)pdu->pdu_connection;
        assert(conn->conn_conf.isc_iser != 0);

        pdu_set_data_segment_length(pdu, pdu->pdu_data_len);

        memset(&ids, 0, sizeof(ids));
        ids.ids_session_id = conn->conn_session_id;
        ids.ids_bhs = pdu->pdu_bhs;
        ids.ids_data_segment_len = pdu->pdu_data_len;
        ids.ids_data_segment = pdu->pdu_data;

        error = ioctl(conn->conn_iscsi_fd, ISCSIDSEND, &ids);
        if (error != 0)
                log_err(1, "ISCSIDSEND");
}

#endif /* ICL_KERNEL_PROXY */

static void
resolve_addr(const struct connection *conn, const char *address,
    struct addrinfo **ai, bool initiator_side)
{
        struct addrinfo hints;
        char *arg, *addr, *ch, *tofree;
        const char *port;
        int error, colons = 0;

        tofree = arg = checked_strdup(address);

        if (arg[0] == '\0') {
                fail(conn, "empty address");
                log_errx(1, "empty address");
        }
        if (arg[0] == '[') {
                /*
                 * IPv6 address in square brackets, perhaps with port.
                 */
                arg++;
                addr = strsep(&arg, "]");
                if (arg == NULL) {
                        fail(conn, "malformed address");
                        log_errx(1, "malformed address %s", address);
                }
                if (arg[0] == '\0') {
                        port = NULL;
                } else if (arg[0] == ':') {
                        port = arg + 1;
                } else {
                        fail(conn, "malformed address");
                        log_errx(1, "malformed address %s", address);
                }
        } else {
                /*
                 * Either IPv6 address without brackets - and without
                 * a port - or IPv4 address.  Just count the colons.
                 */
                for (ch = arg; *ch != '\0'; ch++) {
                        if (*ch == ':')
                                colons++;
                }
                if (colons > 1) {
                        addr = arg;
                        port = NULL;
                } else {
                        addr = strsep(&arg, ":");
                        if (arg == NULL)
                                port = NULL;
                        else
                                port = arg;
                }
        }

        if (port == NULL && !initiator_side)
                port = "3260";

        memset(&hints, 0, sizeof(hints));
        hints.ai_family = PF_UNSPEC;
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_flags = AI_ADDRCONFIG | AI_NUMERICSERV;
        if (initiator_side)
                hints.ai_flags |= AI_PASSIVE;

        error = getaddrinfo(addr, port, &hints, ai);
        if (error != 0) {
                fail(conn, gai_strerror(error));
                log_errx(1, "getaddrinfo for %s failed: %s",
                    address, gai_strerror(error));
        }

        free(tofree);
}

static struct iscsid_connection *
connection_new(int iscsi_fd, const struct iscsi_daemon_request *request)
{
        struct iscsid_connection *conn;
        struct addrinfo *from_ai, *to_ai;
        const char *from_addr, *to_addr;
#ifdef ICL_KERNEL_PROXY
        struct iscsi_daemon_connect idc;
#endif
        int error, optval;

        conn = calloc(1, sizeof(*conn));
        if (conn == NULL)
                log_err(1, "calloc");

        connection_init(&conn->conn, &conn_ops,
            request->idr_conf.isc_iser != 0);
        conn->conn_protocol_level = 0;
        conn->conn_initial_r2t = true;
        conn->conn_iscsi_fd = iscsi_fd;

        conn->conn_session_id = request->idr_session_id;
        memcpy(&conn->conn_conf, &request->idr_conf, sizeof(conn->conn_conf));
        memcpy(&conn->conn.conn_isid, &request->idr_isid,
            sizeof(conn->conn.conn_isid));
        conn->conn.conn_tsih = request->idr_tsih;

        from_addr = conn->conn_conf.isc_initiator_addr;
        to_addr = conn->conn_conf.isc_target_addr;

        if (from_addr[0] != '\0')
                resolve_addr(&conn->conn, from_addr, &from_ai, true);
        else
                from_ai = NULL;

        resolve_addr(&conn->conn, to_addr, &to_ai, false);

#ifdef ICL_KERNEL_PROXY
        if (conn->conn_conf.isc_iser) {
                memset(&idc, 0, sizeof(idc));
                idc.idc_session_id = conn->conn_session_id;
                if (conn->conn_conf.isc_iser)
                        idc.idc_iser = 1;
                idc.idc_domain = to_ai->ai_family;
                idc.idc_socktype = to_ai->ai_socktype;
                idc.idc_protocol = to_ai->ai_protocol;
                if (from_ai != NULL) {
                        idc.idc_from_addr = from_ai->ai_addr;
                        idc.idc_from_addrlen = from_ai->ai_addrlen;
                }
                idc.idc_to_addr = to_ai->ai_addr;
                idc.idc_to_addrlen = to_ai->ai_addrlen;

                log_debugx("connecting to %s using ICL kernel proxy", to_addr);
                error = ioctl(iscsi_fd, ISCSIDCONNECT, &idc);
                if (error != 0) {
                        fail(&conn->conn, strerror(errno));
                        log_err(1, "failed to connect to %s "
                            "using ICL kernel proxy: ISCSIDCONNECT", to_addr);
                }

                if (from_ai != NULL)
                        freeaddrinfo(from_ai);
                freeaddrinfo(to_ai);

                return (conn);
        }
#endif /* ICL_KERNEL_PROXY */

        if (conn->conn_conf.isc_iser) {
                fail(&conn->conn, "iSER not supported");
                log_errx(1, "iscsid(8) compiled without ICL_KERNEL_PROXY "
                    "does not support iSER");
        }

        conn->conn.conn_socket = socket(to_ai->ai_family, to_ai->ai_socktype,
            to_ai->ai_protocol);
        if (conn->conn.conn_socket < 0) {
                fail(&conn->conn, strerror(errno));
                log_err(1, "failed to create socket for %s", from_addr);
        }
        optval = SOCKBUF_SIZE;
        if (setsockopt(conn->conn.conn_socket, SOL_SOCKET, SO_RCVBUF,
            &optval, sizeof(optval)) == -1)
                log_warn("setsockopt(SO_RCVBUF) failed");
        optval = SOCKBUF_SIZE;
        if (setsockopt(conn->conn.conn_socket, SOL_SOCKET, SO_SNDBUF,
            &optval, sizeof(optval)) == -1)
                log_warn("setsockopt(SO_SNDBUF) failed");
        optval = 1;
        if (setsockopt(conn->conn.conn_socket, SOL_SOCKET, SO_NO_DDP,
            &optval, sizeof(optval)) == -1)
                log_warn("setsockopt(SO_NO_DDP) failed");
        if (conn->conn_conf.isc_dscp != -1) {
                int tos = conn->conn_conf.isc_dscp << 2;
                if (to_ai->ai_family == AF_INET) {
                        if (setsockopt(conn->conn.conn_socket,
                            IPPROTO_IP, IP_TOS,
                            &tos, sizeof(tos)) == -1)
                                log_warn("setsockopt(IP_TOS) "
                                    "failed for %s",
                                    from_addr);
                } else
                if (to_ai->ai_family == AF_INET6) {
                        if (setsockopt(conn->conn.conn_socket,
                            IPPROTO_IPV6, IPV6_TCLASS,
                            &tos, sizeof(tos)) == -1)
                                log_warn("setsockopt(IPV6_TCLASS) "
                                    "failed for %s",
                                    from_addr);
                }
        }
        if (conn->conn_conf.isc_pcp != -1) {
                int pcp = conn->conn_conf.isc_pcp;
                if (to_ai->ai_family == AF_INET) {
                        if (setsockopt(conn->conn.conn_socket,
                            IPPROTO_IP, IP_VLAN_PCP,
                            &pcp, sizeof(pcp)) == -1)
                                log_warn("setsockopt(IP_VLAN_PCP) "
                                    "failed for %s",
                                    from_addr);
                } else
                if (to_ai->ai_family == AF_INET6) {
                        if (setsockopt(conn->conn.conn_socket,
                            IPPROTO_IPV6, IPV6_VLAN_PCP,
                            &pcp, sizeof(pcp)) == -1)
                                log_warn("setsockopt(IPV6_VLAN_PCP) "
                                    "failed for %s",
                                    from_addr);
                }
        }
        /*
         * Reduce TCP SYN_SENT timeout while
         * no connectivity exists, to allow
         * rapid reuse of the available slots.
         */
        int keepinit = 0;
        if (conn->conn_conf.isc_login_timeout > 0) {
                keepinit = conn->conn_conf.isc_login_timeout;
                log_debugx("session specific LoginTimeout at %d sec",
                        keepinit);
        }
        if (conn->conn_conf.isc_login_timeout == -1) {
                int value;
                size_t size = sizeof(value);
                if (sysctlbyname("kern.iscsi.login_timeout",
                    &value, &size, NULL, 0) == 0) {
                        keepinit = value;
                        log_debugx("global login_timeout at %d sec",
                                keepinit);
                }
        }
        if (keepinit > 0) {
                if (setsockopt(conn->conn.conn_socket,
                    IPPROTO_TCP, TCP_KEEPINIT,
                    &keepinit, sizeof(keepinit)) == -1)
                        log_warnx("setsockopt(TCP_KEEPINIT) "
                            "failed for %s", to_addr);
        }
        if (from_ai != NULL) {
                error = bind(conn->conn.conn_socket, from_ai->ai_addr,
                    from_ai->ai_addrlen);
                if (error != 0) {
                        fail(&conn->conn, strerror(errno));
                        log_err(1, "failed to bind to %s", from_addr);
                }
        }
        log_debugx("connecting to %s", to_addr);
        error = connect(conn->conn.conn_socket, to_ai->ai_addr,
            to_ai->ai_addrlen);
        if (error != 0) {
                fail(&conn->conn, strerror(errno));
                log_err(1, "failed to connect to %s", to_addr);
        }

        if (from_ai != NULL)
                freeaddrinfo(from_ai);
        freeaddrinfo(to_ai);

        return (conn);
}

static void
limits(struct iscsid_connection *conn)
{
        struct iscsi_daemon_limits idl;
        struct iscsi_session_limits *isl;
        int error;

        log_debugx("fetching limits from the kernel");

        memset(&idl, 0, sizeof(idl));
        idl.idl_session_id = conn->conn_session_id;
        idl.idl_socket = conn->conn.conn_socket;

        error = ioctl(conn->conn_iscsi_fd, ISCSIDLIMITS, &idl);
        if (error != 0)
                log_err(1, "ISCSIDLIMITS");
        
        /*
         * Read the driver limits and provide reasonable defaults for the ones
         * the driver doesn't care about.  If a max_snd_dsl is not explicitly
         * provided by the driver then we'll make sure both conn->max_snd_dsl
         * and isl->max_snd_dsl are set to the rcv_dsl.  This preserves historic
         * behavior.
         */
        isl = &conn->conn_limits;
        memcpy(isl, &idl.idl_limits, sizeof(*isl));
        if (isl->isl_max_recv_data_segment_length == 0)
                isl->isl_max_recv_data_segment_length = (1 << 24) - 1;
        if (isl->isl_max_send_data_segment_length == 0)
                isl->isl_max_send_data_segment_length =
                    isl->isl_max_recv_data_segment_length;
        if (isl->isl_max_burst_length == 0)
                isl->isl_max_burst_length = (1 << 24) - 1;
        if (isl->isl_first_burst_length == 0)
                isl->isl_first_burst_length = (1 << 24) - 1;
        if (isl->isl_first_burst_length > isl->isl_max_burst_length)
                isl->isl_first_burst_length = isl->isl_max_burst_length;

        /*
         * Limit default send length in case it won't be negotiated.
         * We can't do it for other limits, since they may affect both
         * sender and receiver operation, and we must obey defaults.
         */
        if (conn->conn.conn_max_send_data_segment_length >
            isl->isl_max_send_data_segment_length) {
                conn->conn.conn_max_send_data_segment_length =
                    isl->isl_max_send_data_segment_length;
        }
}

static void
handoff(struct iscsid_connection *conn)
{
        struct iscsi_daemon_handoff idh;
        int error;

        log_debugx("handing off connection to the kernel");

        memset(&idh, 0, sizeof(idh));
        idh.idh_session_id = conn->conn_session_id;
        idh.idh_socket = conn->conn.conn_socket;
        strlcpy(idh.idh_target_alias, conn->conn_target_alias,
            sizeof(idh.idh_target_alias));
        idh.idh_tsih = conn->conn.conn_tsih;
        idh.idh_statsn = conn->conn.conn_statsn;
        idh.idh_protocol_level = conn->conn_protocol_level;
        idh.idh_header_digest = conn->conn.conn_header_digest;
        idh.idh_data_digest = conn->conn.conn_data_digest;
        idh.idh_initial_r2t = conn->conn_initial_r2t;
        idh.idh_immediate_data = conn->conn.conn_immediate_data;
        idh.idh_max_recv_data_segment_length =
            conn->conn.conn_max_recv_data_segment_length;
        idh.idh_max_send_data_segment_length =
            conn->conn.conn_max_send_data_segment_length;
        idh.idh_max_burst_length = conn->conn.conn_max_burst_length;
        idh.idh_first_burst_length = conn->conn.conn_first_burst_length;

        error = ioctl(conn->conn_iscsi_fd, ISCSIDHANDOFF, &idh);
        if (error != 0)
                log_err(1, "ISCSIDHANDOFF");
}

void
fail(const struct connection *base_conn, const char *reason)
{
        const struct iscsid_connection *conn;
        struct iscsi_daemon_fail idf;
        int error, saved_errno;

        conn = (const struct iscsid_connection *)base_conn;
        saved_errno = errno;

        memset(&idf, 0, sizeof(idf));
        idf.idf_session_id = conn->conn_session_id;
        strlcpy(idf.idf_reason, reason, sizeof(idf.idf_reason));

        error = ioctl(conn->conn_iscsi_fd, ISCSIDFAIL, &idf);
        if (error != 0)
                log_err(1, "ISCSIDFAIL");

        errno = saved_errno;
}

/*
 * XXX: I CANT INTO LATIN
 */
static void
capsicate(struct iscsid_connection *conn)
{
        cap_rights_t rights;
        const unsigned long cmds[] = {
#ifdef ICL_KERNEL_PROXY
                ISCSIDCONNECT,
                ISCSIDSEND,
                ISCSIDRECEIVE,
#endif
                ISCSIDLIMITS,
                ISCSIDHANDOFF,
                ISCSIDFAIL,
                ISCSISADD,
                ISCSISREMOVE,
                ISCSISMODIFY
        };

        cap_rights_init(&rights, CAP_IOCTL);
        if (caph_rights_limit(conn->conn_iscsi_fd, &rights) < 0)
                log_err(1, "cap_rights_limit");

        if (caph_ioctls_limit(conn->conn_iscsi_fd, cmds, nitems(cmds)) < 0)
                log_err(1, "cap_ioctls_limit");

        if (caph_enter() != 0)
                log_err(1, "cap_enter");

        if (cap_sandboxed())
                log_debugx("Capsicum capability mode enabled");
        else
                log_warnx("Capsicum capability mode not supported");
}

static bool
timed_out(void)
{

        return (sigalrm_received);
}

static void
sigalrm_handler(int dummy __unused)
{
        /*
         * It would be easiest to just log an error and exit.  We can't
         * do this, though, because log_errx() is not signal safe, since
         * it calls syslog(3).  Instead, set a flag checked by pdu_send()
         * and pdu_receive(), to call log_errx() there.  Should they fail
         * to notice, we'll exit here one second later.
         */
        if (sigalrm_received) {
                /*
                 * Oh well.  Just give up and quit.
                 */
                _exit(2);
        }

        sigalrm_received = true;
}

static void
set_timeout(int timeout)
{
        struct sigaction sa;
        struct itimerval itv;
        int error;

        if (timeout <= 0) {
                log_debugx("session timeout disabled");
                return;
        }

        bzero(&sa, sizeof(sa));
        sa.sa_handler = sigalrm_handler;
        sigfillset(&sa.sa_mask);
        error = sigaction(SIGALRM, &sa, NULL);
        if (error != 0)
                log_err(1, "sigaction");

        /*
         * First SIGALRM will arive after conf_timeout seconds.
         * If we do nothing, another one will arrive a second later.
         */
        bzero(&itv, sizeof(itv));
        itv.it_interval.tv_sec = 1;
        itv.it_value.tv_sec = timeout;

        log_debugx("setting session timeout to %d seconds",
            timeout);
        error = setitimer(ITIMER_REAL, &itv, NULL);
        if (error != 0)
                log_err(1, "setitimer");
}

static void
sigchld_handler(int dummy __unused)
{

        /*
         * The only purpose of this handler is to make SIGCHLD
         * interrupt the ISCSIDWAIT ioctl(2), so we can call
         * wait_for_children().
         */
}

static void
register_sigchld(void)
{
        struct sigaction sa;
        int error;

        bzero(&sa, sizeof(sa));
        sa.sa_handler = sigchld_handler;
        sigfillset(&sa.sa_mask);
        error = sigaction(SIGCHLD, &sa, NULL);
        if (error != 0)
                log_err(1, "sigaction");

}

static void
handle_request(int iscsi_fd, const struct iscsi_daemon_request *request, int timeout)
{
        struct iscsid_connection *conn;

        log_set_peer_addr(request->idr_conf.isc_target_addr);
        if (request->idr_conf.isc_target[0] != '\0') {
                log_set_peer_name(request->idr_conf.isc_target);
                setproctitle("%s (%s)", request->idr_conf.isc_target_addr, request->idr_conf.isc_target);
        } else {
                setproctitle("%s", request->idr_conf.isc_target_addr);
        }

        conn = connection_new(iscsi_fd, request);
        capsicate(conn);
        limits(conn);
        set_timeout(timeout);
        login(conn);
        if (conn->conn_conf.isc_discovery != 0)
                discovery(conn);
        else
                handoff(conn);

        log_debugx("nothing more to do; exiting");
        exit (0);
}

static int
wait_for_children(bool block)
{
        pid_t pid;
        int status;
        int num = 0;

        for (;;) {
                /*
                 * If "block" is true, wait for at least one process.
                 */
                if (block && num == 0)
                        pid = wait4(-1, &status, 0, NULL);
                else
                        pid = wait4(-1, &status, WNOHANG, NULL);
                if (pid <= 0)
                        break;
                if (WIFSIGNALED(status)) {
                        log_warnx("child process %d terminated with signal %d",
                            pid, WTERMSIG(status));
                } else if (WEXITSTATUS(status) != 0) {
                        log_warnx("child process %d terminated with exit status %d",
                            pid, WEXITSTATUS(status));
                } else {
                        log_debugx("child process %d terminated gracefully", pid);
                }
                num++;
        }

        return (num);
}

int
main(int argc, char **argv)
{
        int ch, debug = 0, error, iscsi_fd, maxproc = 30, retval, saved_errno,
            timeout = 60;
        bool dont_daemonize = false;
        struct pidfh *pidfh;
        pid_t pid, otherpid;
        const char *pidfile_path = DEFAULT_PIDFILE;
        struct iscsi_daemon_request request;

        while ((ch = getopt(argc, argv, "P:dl:m:t:")) != -1) {
                switch (ch) {
                case 'P':
                        pidfile_path = optarg;
                        break;
                case 'd':
                        dont_daemonize = true;
                        debug++;
                        break;
                case 'l':
                        debug = atoi(optarg);
                        break;
                case 'm':
                        maxproc = atoi(optarg);
                        break;
                case 't':
                        timeout = atoi(optarg);
                        break;
                case '?':
                default:
                        usage();
                }
        }
        argc -= optind;
        if (argc != 0)
                usage();

        log_init(debug);

        pidfh = pidfile_open(pidfile_path, 0600, &otherpid);
        if (pidfh == NULL) {
                if (errno == EEXIST)
                        log_errx(1, "daemon already running, pid: %jd.",
                            (intmax_t)otherpid);
                log_err(1, "cannot open or create pidfile \"%s\"",
                    pidfile_path);
        }

        iscsi_fd = open(ISCSI_PATH, O_RDWR);
        if (iscsi_fd < 0 && errno == ENOENT) {
                saved_errno = errno;
                retval = kldload("iscsi");
                if (retval != -1)
                        iscsi_fd = open(ISCSI_PATH, O_RDWR);
                else
                        errno = saved_errno;
        }
        if (iscsi_fd < 0)
                log_err(1, "failed to open %s", ISCSI_PATH);

        if (dont_daemonize == false) {
                if (daemon(0, 0) == -1) {
                        log_warn("cannot daemonize");
                        pidfile_remove(pidfh);
                        exit(1);
                }
        }

        pidfile_write(pidfh);

        register_sigchld();

        for (;;) {
                log_debugx("waiting for request from the kernel");

                memset(&request, 0, sizeof(request));
                error = ioctl(iscsi_fd, ISCSIDWAIT, &request);
                if (error != 0) {
                        if (errno == EINTR) {
                                nchildren -= wait_for_children(false);
                                assert(nchildren >= 0);
                                continue;
                        }

                        log_err(1, "ISCSIDWAIT");
                }

                if (dont_daemonize) {
                        log_debugx("not forking due to -d flag; "
                            "will exit after servicing a single request");
                } else {
                        nchildren -= wait_for_children(false);
                        assert(nchildren >= 0);

                        while (maxproc > 0 && nchildren >= maxproc) {
                                log_debugx("maxproc limit of %d child processes hit; "
                                    "waiting for child process to exit", maxproc);
                                nchildren -= wait_for_children(true);
                                assert(nchildren >= 0);
                        }
                        log_debugx("incoming connection; forking child process #%d",
                            nchildren);
                        nchildren++;

                        pid = fork();
                        if (pid < 0)
                                log_err(1, "fork");
                        if (pid > 0)
                                continue;
                }

                pidfile_close(pidfh);
                handle_request(iscsi_fd, &request, timeout);
        }

        return (0);
}