/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
 * 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 AUTHORS 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 AUTHORS 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 <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <inttypes.h>
#include <libgen.h>
#include <pthread.h>
#include <signal.h>
#include <err.h>
#include <errno.h>
#include <assert.h>

#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/time.h>
#include <sys/bio.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>

#include "ggate.h"


static enum { UNSET, CREATE, DESTROY, LIST, RESCUE } action = UNSET;

static const char *path = NULL;
static const char *host = NULL;
static int unit = G_GATE_UNIT_AUTO;
static unsigned flags = 0;
static int direct_flag = 0;
static int force = 0;
static unsigned queue_size = G_GATE_QUEUE_SIZE;
static unsigned port = G_GATE_PORT;
static off_t mediasize;
static unsigned sectorsize = 0;
static unsigned timeout = G_GATE_TIMEOUT;
static int sendfd, recvfd;
static uint32_t token;
static pthread_t sendtd, recvtd;
static int reconnect;
static int initialbuffersize = 131072;

static void
usage(void)
{

        fprintf(stderr, "usage: %s create [-nv] [-o <ro|wo|rw>] "
            "[-o <direct>] [-p port] "
            "[-q queue_size] [-R rcvbuf] [-S sndbuf] [-s sectorsize] "
            "[-t timeout] [-u unit] <host> <path>\n", getprogname());
        fprintf(stderr, "       %s rescue [-nv] [-o <ro|wo|rw>] "
            "[-o <direct>] [-p port] "
            "[-R rcvbuf] [-S sndbuf] <-u unit> <host> <path>\n", getprogname());
        fprintf(stderr, "       %s destroy [-f] <-u unit>\n", getprogname());
        fprintf(stderr, "       %s list [-v] [-u unit]\n", getprogname());
        exit(EXIT_FAILURE);
}

static void *
send_thread(void *arg __unused)
{
        struct g_gate_ctl_io ggio;
        struct g_gate_hdr hdr;
        size_t buf_capacity;
        ssize_t numbytesprocd;
        int error;
        char *newbuf;

        g_gate_log(LOG_NOTICE, "%s: started!", __func__);

        buf_capacity = initialbuffersize;

        ggio.gctl_version = G_GATE_VERSION;
        ggio.gctl_unit = unit;
        ggio.gctl_data = malloc(buf_capacity);
        if (ggio.gctl_data == NULL) {
                g_gate_log(LOG_ERR, "%s: Cannot alloc buffer.", __func__);
                pthread_exit(NULL);
        }

        for (;;) {
                ggio.gctl_length = buf_capacity;
                ggio.gctl_error = 0;
                g_gate_ioctl(G_GATE_CMD_START, &ggio);
                error = ggio.gctl_error;
                switch (error) {
                case 0:
                        break;
                case ECANCELED:
                        if (reconnect)
                                break;
                        /* Exit gracefully. */
                        g_gate_close_device();
                        exit(EXIT_SUCCESS);

                case ENOMEM:
                {
                        /* Buffer too small. */
                        g_gate_log(LOG_DEBUG, "buffer too small. new size: %u",
                            ggio.gctl_length);
                        newbuf = malloc(ggio.gctl_length);
                        if (newbuf != NULL) {
                                free(ggio.gctl_data);
                                ggio.gctl_data = newbuf;
                                buf_capacity = ggio.gctl_length;
                                continue;
                        }
                        /* FALLTHROUGH */
                }

                case ENXIO:
                default:
                        g_gate_xlog("ioctl(/dev/%s): %s.", G_GATE_CTL_NAME,
                            strerror(error));
                }

                if (reconnect)
                        break;

                switch (ggio.gctl_cmd) {
                case BIO_READ:
                        hdr.gh_cmd = GGATE_CMD_READ;
                        break;
                case BIO_WRITE:
                        hdr.gh_cmd = GGATE_CMD_WRITE;
                        break;
                case BIO_FLUSH:
                        hdr.gh_cmd = GGATE_CMD_FLUSH;
                        break;
                default:
                        g_gate_log(LOG_NOTICE, "Unknown gctl_cmd: %i",
                            ggio.gctl_cmd);
                        ggio.gctl_error = EOPNOTSUPP;
                        g_gate_ioctl(G_GATE_CMD_DONE, &ggio);
                        continue;
                }

                hdr.gh_seq = ggio.gctl_seq;
                hdr.gh_offset = ggio.gctl_offset;
                hdr.gh_length = ggio.gctl_length;
                hdr.gh_error = 0;
                g_gate_swap2n_hdr(&hdr);

                numbytesprocd = g_gate_send(sendfd, &hdr, sizeof(hdr), MSG_NOSIGNAL);
                g_gate_log(LOG_DEBUG, "Sent hdr packet.");
                g_gate_swap2h_hdr(&hdr);
                if (reconnect)
                        break;
                if (numbytesprocd != sizeof(hdr)) {
                        g_gate_log(LOG_ERR, "Lost connection 1.");
                        reconnect = 1;
                        pthread_kill(recvtd, SIGUSR1);
                        break;
                }

                if (hdr.gh_cmd == GGATE_CMD_WRITE) {
                        numbytesprocd = g_gate_send(sendfd, ggio.gctl_data,
                            ggio.gctl_length, MSG_NOSIGNAL);
                        if (reconnect)
                                break;
                        if (numbytesprocd != ggio.gctl_length) {
                                g_gate_log(LOG_ERR, "Lost connection 2 (%zd != %zd).",
                                    numbytesprocd, (ssize_t)ggio.gctl_length);
                                reconnect = 1;
                                pthread_kill(recvtd, SIGUSR1);
                                break;
                        }
                        g_gate_log(LOG_DEBUG, "Sent %zd bytes (offset=%"
                            PRIu64 ", length=%" PRIu32 ").", numbytesprocd,
                            hdr.gh_offset, hdr.gh_length);
                }
        }
        g_gate_log(LOG_DEBUG, "%s: Died.", __func__);
        return (NULL);
}

static void *
recv_thread(void *arg __unused)
{
        struct g_gate_ctl_io ggio;
        struct g_gate_hdr hdr;
        ssize_t buf_capacity;
        ssize_t numbytesprocd;
        char *newbuf;

        g_gate_log(LOG_NOTICE, "%s: started!", __func__);

        buf_capacity = initialbuffersize;

        ggio.gctl_version = G_GATE_VERSION;
        ggio.gctl_unit = unit;
        ggio.gctl_data = malloc(buf_capacity);
        if (ggio.gctl_data == NULL) {
                g_gate_log(LOG_ERR, "%s: Cannot alloc buffer.", __func__);
                pthread_exit(NULL);
        }

        for (;;) {
                numbytesprocd = g_gate_recv(recvfd, &hdr, sizeof(hdr), MSG_WAITALL);
                if (reconnect)
                        break;
                g_gate_swap2h_hdr(&hdr);
                if (numbytesprocd != sizeof(hdr)) {
                        if (numbytesprocd == -1 && errno == EAGAIN)
                                continue;
                        g_gate_log(LOG_ERR, "Lost connection 3.");
                        reconnect = 1;
                        pthread_kill(sendtd, SIGUSR1);
                        break;
                }
                g_gate_log(LOG_DEBUG, "Received hdr packet.");

                ggio.gctl_seq = hdr.gh_seq;
                ggio.gctl_cmd = hdr.gh_cmd;
                ggio.gctl_offset = hdr.gh_offset;
                ggio.gctl_length = hdr.gh_length;
                ggio.gctl_error = hdr.gh_error;

                if (ggio.gctl_length > buf_capacity) {
                        newbuf = malloc(ggio.gctl_length);
                        if (newbuf != NULL) {
                                free(ggio.gctl_data);
                                ggio.gctl_data = newbuf;
                                buf_capacity = ggio.gctl_length;
                        } else {
                                g_gate_log(LOG_ERR, "Received too big response: %zd",
                                    ggio.gctl_length);
                                break;
                        }
                }

                if (ggio.gctl_error == 0 && ggio.gctl_cmd == GGATE_CMD_READ) {
                        numbytesprocd = g_gate_recv(recvfd, ggio.gctl_data,
                            ggio.gctl_length, MSG_WAITALL);
                        if (reconnect)
                                break;
                        g_gate_log(LOG_DEBUG, "Received data packet.");
                        if (numbytesprocd != ggio.gctl_length) {
                                g_gate_log(LOG_ERR, "Lost connection 4.");
                                reconnect = 1;
                                pthread_kill(sendtd, SIGUSR1);
                                break;
                        }
                        g_gate_log(LOG_DEBUG, "Received %d bytes (offset=%"
                            PRIu64 ", length=%" PRIu32 ").", numbytesprocd,
                            hdr.gh_offset, hdr.gh_length);
                }

                g_gate_ioctl(G_GATE_CMD_DONE, &ggio);
        }
        g_gate_log(LOG_DEBUG, "%s: Died.", __func__);
        pthread_exit(NULL);
}

static int
handshake(int dir)
{
        struct g_gate_version ver;
        struct g_gate_cinit cinit;
        struct g_gate_sinit sinit;
        struct sockaddr_in serv;
        int sfd;

        /*
         * Do the network stuff.
         */
        bzero(&serv, sizeof(serv));
        serv.sin_family = AF_INET;
        serv.sin_addr.s_addr = g_gate_str2ip(host);
        if (serv.sin_addr.s_addr == INADDR_NONE) {
                g_gate_log(LOG_DEBUG, "Invalid IP/host name: %s.", host);
                return (-1);
        }
        serv.sin_port = htons(port);
        sfd = socket(AF_INET, SOCK_STREAM, 0);
        if (sfd == -1) {
                g_gate_log(LOG_DEBUG, "Cannot open socket: %s.",
                    strerror(errno));
                return (-1);
        }

        g_gate_socket_settings(sfd);

        if (connect(sfd, (struct sockaddr *)&serv, sizeof(serv)) == -1) {
                g_gate_log(LOG_DEBUG, "Cannot connect to server: %s.",
                    strerror(errno));
                close(sfd);
                return (-1);
        }

        g_gate_log(LOG_INFO, "Connected to the server: %s:%d.", host, port);

        /*
         * Create and send version packet.
         */
        g_gate_log(LOG_DEBUG, "Sending version packet.");
        assert(strlen(GGATE_MAGIC) == sizeof(ver.gv_magic));
        bcopy(GGATE_MAGIC, ver.gv_magic, sizeof(ver.gv_magic));
        ver.gv_version = GGATE_VERSION;
        ver.gv_error = 0;
        g_gate_swap2n_version(&ver);
        if (g_gate_send(sfd, &ver, sizeof(ver), MSG_NOSIGNAL) == -1) {
                g_gate_log(LOG_DEBUG, "Error while sending version packet: %s.",
                    strerror(errno));
                close(sfd);
                return (-1);
        }
        bzero(&ver, sizeof(ver));
        if (g_gate_recv(sfd, &ver, sizeof(ver), MSG_WAITALL) == -1) {
                g_gate_log(LOG_DEBUG, "Error while receiving data: %s.",
                    strerror(errno));
                close(sfd);
                return (-1);
        }
        if (ver.gv_error != 0) {
                g_gate_log(LOG_DEBUG, "Version verification problem: %s.",
                    strerror(errno));
                close(sfd);
                return (-1);
        }

        /*
         * Create and send initial packet.
         */
        g_gate_log(LOG_DEBUG, "Sending initial packet.");
        if (strlcpy(cinit.gc_path, path, sizeof(cinit.gc_path)) >=
            sizeof(cinit.gc_path)) {
                g_gate_log(LOG_DEBUG, "Path name too long.");
                close(sfd);
                return (-1);
        }
        cinit.gc_flags = flags | direct_flag | dir;
        cinit.gc_token = token;
        cinit.gc_nconn = 2;
        g_gate_swap2n_cinit(&cinit);
        if (g_gate_send(sfd, &cinit, sizeof(cinit), MSG_NOSIGNAL) == -1) {
                g_gate_log(LOG_DEBUG, "Error while sending initial packet: %s.",
                    strerror(errno));
                close(sfd);
                return (-1);
        }
        g_gate_swap2h_cinit(&cinit);

        /*
         * Receiving initial packet from server.
         */
        g_gate_log(LOG_DEBUG, "Receiving initial packet.");
        if (g_gate_recv(sfd, &sinit, sizeof(sinit), MSG_WAITALL) == -1) {
                g_gate_log(LOG_DEBUG, "Error while receiving data: %s.",
                    strerror(errno));
                close(sfd);
                return (-1);
        }
        g_gate_swap2h_sinit(&sinit);
        if (sinit.gs_error != 0) {
                g_gate_log(LOG_DEBUG, "Error from server: %s.",
                    strerror(sinit.gs_error));
                close(sfd);
                return (-1);
        }
        g_gate_log(LOG_DEBUG, "Received initial packet.");

        mediasize = sinit.gs_mediasize;
        if (sectorsize == 0)
                sectorsize = sinit.gs_sectorsize;

        return (sfd);
}

static void
mydaemon(void)
{

        if (g_gate_verbose > 0)
                return;
        if (daemon(0, 0) == 0)
                return;
        if (action == CREATE)
                g_gate_destroy(unit, 1);
        err(EXIT_FAILURE, "Cannot daemonize");
}

static int
g_gatec_connect(void)
{

        token = arc4random();
        /*
         * Our receive descriptor is connected to the send descriptor on the
         * server side.
         */
        recvfd = handshake(GGATE_FLAG_SEND);
        if (recvfd == -1)
                return (0);
        /*
         * Our send descriptor is connected to the receive descriptor on the
         * server side.
         */
        sendfd = handshake(GGATE_FLAG_RECV);
        if (sendfd == -1)
                return (0);
        return (1);
}

static void
g_gatec_start(void)
{
        int error;

        reconnect = 0;
        error = pthread_create(&recvtd, NULL, recv_thread, NULL);
        if (error != 0) {
                g_gate_destroy(unit, 1);
                g_gate_xlog("pthread_create(recv_thread): %s.",
                    strerror(error));
        }
        sendtd = pthread_self();
        send_thread(NULL);
        /* Disconnected. */
        close(sendfd);
        close(recvfd);
}

static void
signop(int sig __unused)
{

        /* Do nothing. */
}

static void
g_gatec_loop(void)
{
        struct g_gate_ctl_cancel ggioc;

        signal(SIGUSR1, signop);
        for (;;) {
                g_gatec_start();
                g_gate_log(LOG_NOTICE, "Disconnected [%s %s]. Connecting...",
                    host, path);
                while (!g_gatec_connect()) {
                        sleep(2);
                        g_gate_log(LOG_NOTICE, "Connecting [%s %s]...", host,
                            path);
                }
                ggioc.gctl_version = G_GATE_VERSION;
                ggioc.gctl_unit = unit;
                ggioc.gctl_seq = 0;
                g_gate_ioctl(G_GATE_CMD_CANCEL, &ggioc);
        }
}

static void
g_gatec_create(void)
{
        struct g_gate_ctl_create ggioc;

        if (!g_gatec_connect())
                g_gate_xlog("Cannot connect: %s.", strerror(errno));

        /*
         * Ok, got both sockets, time to create provider.
         */
        memset(&ggioc, 0, sizeof(ggioc));
        ggioc.gctl_version = G_GATE_VERSION;
        ggioc.gctl_mediasize = mediasize;
        ggioc.gctl_sectorsize = sectorsize;
        ggioc.gctl_flags = flags;
        ggioc.gctl_maxcount = queue_size;
        ggioc.gctl_timeout = timeout;
        ggioc.gctl_unit = unit;
        snprintf(ggioc.gctl_info, sizeof(ggioc.gctl_info), "%s:%u %s", host,
            port, path);
        g_gate_ioctl(G_GATE_CMD_CREATE, &ggioc);
        if (unit == -1) {
                printf("%s%u\n", G_GATE_PROVIDER_NAME, ggioc.gctl_unit);
                fflush(stdout);
        }
        unit = ggioc.gctl_unit;

        mydaemon();
        g_gatec_loop();
}

static void
g_gatec_rescue(void)
{
        struct g_gate_ctl_cancel ggioc;

        if (!g_gatec_connect())
                g_gate_xlog("Cannot connect: %s.", strerror(errno));

        ggioc.gctl_version = G_GATE_VERSION;
        ggioc.gctl_unit = unit;
        ggioc.gctl_seq = 0;
        g_gate_ioctl(G_GATE_CMD_CANCEL, &ggioc);

        mydaemon();
        g_gatec_loop();
}

static void
init_initial_buffer_size(void)
{
        int value;
        size_t intsize;
        intsize = sizeof(initialbuffersize);
        if (sysctlbyname("kern.maxphys", &value, &intsize, NULL, 0) == 0)
                initialbuffersize = value;
}

int
main(int argc, char *argv[])
{

        if (argc < 2)
                usage();
        if (strcasecmp(argv[1], "create") == 0)
                action = CREATE;
        else if (strcasecmp(argv[1], "destroy") == 0)
                action = DESTROY;
        else if (strcasecmp(argv[1], "list") == 0)
                action = LIST;
        else if (strcasecmp(argv[1], "rescue") == 0)
                action = RESCUE;
        else
                usage();
        argc -= 1;
        argv += 1;
        for (;;) {
                int ch;

                ch = getopt(argc, argv, "fno:p:q:R:S:s:t:u:v");
                if (ch == -1)
                        break;
                switch (ch) {
                case 'f':
                        if (action != DESTROY)
                                usage();
                        force = 1;
                        break;
                case 'n':
                        if (action != CREATE && action != RESCUE)
                                usage();
                        nagle = 0;
                        break;
                case 'o':
                        if (action != CREATE && action != RESCUE)
                                usage();
                        if (strcasecmp("ro", optarg) == 0)
                                flags = G_GATE_FLAG_READONLY;
                        else if (strcasecmp("wo", optarg) == 0)
                                flags = G_GATE_FLAG_WRITEONLY;
                        else if (strcasecmp("rw", optarg) == 0)
                                flags = 0;
                        else if (strcasecmp("direct", optarg) == 0)
                                direct_flag = GGATE_FLAG_DIRECT;
                        else {
                                errx(EXIT_FAILURE,
                                    "Invalid argument for '-o' option.");
                        }
                        break;
                case 'p':
                        if (action != CREATE && action != RESCUE)
                                usage();
                        errno = 0;
                        port = strtoul(optarg, NULL, 10);
                        if (port == 0 && errno != 0)
                                errx(EXIT_FAILURE, "Invalid port.");
                        break;
                case 'q':
                        if (action != CREATE)
                                usage();
                        errno = 0;
                        queue_size = strtoul(optarg, NULL, 10);
                        if (queue_size == 0 && errno != 0)
                                errx(EXIT_FAILURE, "Invalid queue_size.");
                        break;
                case 'R':
                        if (action != CREATE && action != RESCUE)
                                usage();
                        errno = 0;
                        rcvbuf = strtoul(optarg, NULL, 10);
                        if (rcvbuf == 0 && errno != 0)
                                errx(EXIT_FAILURE, "Invalid rcvbuf.");
                        break;
                case 'S':
                        if (action != CREATE && action != RESCUE)
                                usage();
                        errno = 0;
                        sndbuf = strtoul(optarg, NULL, 10);
                        if (sndbuf == 0 && errno != 0)
                                errx(EXIT_FAILURE, "Invalid sndbuf.");
                        break;
                case 's':
                        if (action != CREATE)
                                usage();
                        errno = 0;
                        sectorsize = strtoul(optarg, NULL, 10);
                        if (sectorsize == 0 && errno != 0)
                                errx(EXIT_FAILURE, "Invalid sectorsize.");
                        break;
                case 't':
                        if (action != CREATE)
                                usage();
                        errno = 0;
                        timeout = strtoul(optarg, NULL, 10);
                        if (timeout == 0 && errno != 0)
                                errx(EXIT_FAILURE, "Invalid timeout.");
                        break;
                case 'u':
                        errno = 0;
                        unit = strtol(optarg, NULL, 10);
                        if (unit == 0 && errno != 0)
                                errx(EXIT_FAILURE, "Invalid unit number.");
                        break;
                case 'v':
                        if (action == DESTROY)
                                usage();
                        g_gate_verbose++;
                        break;
                default:
                        usage();
                }
        }
        argc -= optind;
        argv += optind;

        init_initial_buffer_size();

        switch (action) {
        case CREATE:
                if (argc != 2)
                        usage();
                g_gate_load_module();
                g_gate_open_device();
                host = argv[0];
                path = argv[1];
                g_gatec_create();
                break;
        case DESTROY:
                if (unit == -1) {
                        fprintf(stderr, "Required unit number.\n");
                        usage();
                }
                g_gate_verbose = 1;
                g_gate_open_device();
                g_gate_destroy(unit, force);
                break;
        case LIST:
                g_gate_list(unit, g_gate_verbose);
                break;
        case RESCUE:
                if (argc != 2)
                        usage();
                if (unit == -1) {
                        fprintf(stderr, "Required unit number.\n");
                        usage();
                }
                g_gate_open_device();
                host = argv[0];
                path = argv[1];
                g_gatec_rescue();
                break;
        case UNSET:
        default:
                usage();
        }
        g_gate_close_device();
        exit(EXIT_SUCCESS);
}