/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2012-2013 The FreeBSD Foundation
 * Copyright (c) 2015 Mariusz Zaborski <oshogbo@FreeBSD.org>
 * All rights reserved.
 *
 * This software was developed by Pawel Jakub Dawidek 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 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 <sys/types.h>
#include <sys/socket.h>
#include <sys/nv.h>
#include <sys/procdesc.h>

#include <assert.h>
#include <errno.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "libcasper.h"
#include "libcasper_impl.h"

#define CASPER_VALID_FLAGS      (CASPER_NO_UNIQ)

/*
 * Structure describing communication channel between two separated processes.
 */
#define CAP_CHANNEL_MAGIC       0xcac8a31
struct cap_channel {
        /*
         * Magic value helps to ensure that a pointer to the right structure is
         * passed to our functions.
         */
        int     cch_magic;
        /* Socket descriptor for IPC. */
        int     cch_sock;
        /* Process descriptor for casper. */
        int     cch_pd;
        /* Flags to communicate with casper. */
        int     cch_flags;
};

static bool
cap_add_pd(cap_channel_t *chan, int pd)
{

        if (!fd_is_valid(pd))
                return (false);
        chan->cch_pd = pd;
        return (true);
}

int
cap_channel_flags(const cap_channel_t *chan)
{

        return (chan->cch_flags);
}

cap_channel_t *
cap_init(void)
{
        pid_t pid;
        int sock[2], serrno, pfd;
        bool ret;
        cap_channel_t *chan;

        if (socketpair(PF_UNIX, SOCK_STREAM | SOCK_NONBLOCK, 0,
            sock) == -1) {
                return (NULL);
        }

        pid = pdfork(&pfd, 0);
        if (pid == 0) {
                /* Child. */
                close(sock[0]);
                casper_main_loop(sock[1]);
                /* NOTREACHED. */
        } else if (pid > 0) {
                /* Parent. */
                close(sock[1]);
                chan = cap_wrap(sock[0], 0);
                if (chan == NULL) {
                        serrno = errno;
                        close(sock[0]);
                        close(pfd);
                        errno = serrno;
                        return (NULL);
                }
                ret = cap_add_pd(chan, pfd);
                assert(ret);
                return (chan);
        }

        /* Error. */
        serrno = errno;
        close(sock[0]);
        close(sock[1]);
        errno = serrno;
        return (NULL);
}

cap_channel_t *
cap_wrap(int sock, int flags)
{
        cap_channel_t *chan;

        if (!fd_is_valid(sock))
                return (NULL);

        if ((flags & CASPER_VALID_FLAGS) != flags)
                return (NULL);

        chan = malloc(sizeof(*chan));
        if (chan != NULL) {
                chan->cch_sock = sock;
                chan->cch_pd = -1;
                chan->cch_flags = flags;
                chan->cch_magic = CAP_CHANNEL_MAGIC;
        }

        return (chan);
}

int
cap_unwrap(cap_channel_t *chan, int *flags)
{
        int sock;

        assert(chan != NULL);
        assert(chan->cch_magic == CAP_CHANNEL_MAGIC);

        sock = chan->cch_sock;
        if (chan->cch_pd != -1)
                close(chan->cch_pd);
        if (flags != NULL)
                *flags = chan->cch_flags;
        chan->cch_magic = 0;
        free(chan);

        return (sock);
}

cap_channel_t *
cap_clone(const cap_channel_t *chan)
{
        cap_channel_t *newchan;
        nvlist_t *nvl;
        int newsock;

        assert(chan != NULL);
        assert(chan->cch_magic == CAP_CHANNEL_MAGIC);

        nvl = nvlist_create(channel_nvlist_flags(chan));
        nvlist_add_string(nvl, "cmd", "clone");
        nvl = cap_xfer_nvlist(chan, nvl);
        if (nvl == NULL)
                return (NULL);
        if (nvlist_get_number(nvl, "error") != 0) {
                errno = (int)nvlist_get_number(nvl, "error");
                nvlist_destroy(nvl);
                return (NULL);
        }
        newsock = nvlist_take_descriptor(nvl, "sock");
        nvlist_destroy(nvl);
        newchan = cap_wrap(newsock, chan->cch_flags);
        if (newchan == NULL) {
                int serrno;

                serrno = errno;
                close(newsock);
                errno = serrno;
        }

        return (newchan);
}

void
cap_close(cap_channel_t *chan)
{

        assert(chan != NULL);
        assert(chan->cch_magic == CAP_CHANNEL_MAGIC);

        chan->cch_magic = 0;
        if (chan->cch_pd != -1)
                close(chan->cch_pd);
        close(chan->cch_sock);
        free(chan);
}

int
cap_sock(const cap_channel_t *chan)
{

        assert(chan != NULL);
        assert(chan->cch_magic == CAP_CHANNEL_MAGIC);

        return (chan->cch_sock);
}

int
cap_limit_set(const cap_channel_t *chan, nvlist_t *limits)
{
        nvlist_t *nvlmsg;
        int error;

        nvlmsg = nvlist_create(channel_nvlist_flags(chan));
        nvlist_add_string(nvlmsg, "cmd", "limit_set");
        nvlist_add_nvlist(nvlmsg, "limits", limits);
        nvlmsg = cap_xfer_nvlist(chan, nvlmsg);
        if (nvlmsg == NULL) {
                nvlist_destroy(limits);
                return (-1);
        }
        error = (int)nvlist_get_number(nvlmsg, "error");
        nvlist_destroy(nvlmsg);
        nvlist_destroy(limits);
        if (error != 0) {
                errno = error;
                return (-1);
        }
        return (0);
}

int
cap_limit_get(const cap_channel_t *chan, nvlist_t **limitsp)
{
        nvlist_t *nvlmsg;
        int error;

        nvlmsg = nvlist_create(channel_nvlist_flags(chan));
        nvlist_add_string(nvlmsg, "cmd", "limit_get");
        nvlmsg = cap_xfer_nvlist(chan, nvlmsg);
        if (nvlmsg == NULL)
                return (-1);
        error = (int)nvlist_get_number(nvlmsg, "error");
        if (error != 0) {
                nvlist_destroy(nvlmsg);
                errno = error;
                return (-1);
        }
        if (nvlist_exists_null(nvlmsg, "limits"))
                *limitsp = NULL;
        else
                *limitsp = nvlist_take_nvlist(nvlmsg, "limits");
        nvlist_destroy(nvlmsg);
        return (0);
}

int
cap_send_nvlist(const cap_channel_t *chan, const nvlist_t *nvl)
{

        assert(chan != NULL);
        assert(chan->cch_magic == CAP_CHANNEL_MAGIC);

        return (nvlist_send(chan->cch_sock, nvl));
}

nvlist_t *
cap_recv_nvlist(const cap_channel_t *chan)
{

        assert(chan != NULL);
        assert(chan->cch_magic == CAP_CHANNEL_MAGIC);

        return (nvlist_recv(chan->cch_sock,
            channel_nvlist_flags(chan)));
}

nvlist_t *
cap_xfer_nvlist(const cap_channel_t *chan, nvlist_t *nvl)
{

        assert(chan != NULL);
        assert(chan->cch_magic == CAP_CHANNEL_MAGIC);

        return (nvlist_xfer(chan->cch_sock, nvl,
            channel_nvlist_flags(chan)));
}

cap_channel_t *
cap_service_open(const cap_channel_t *chan, const char *name)
{
        cap_channel_t *newchan;
        nvlist_t *nvl;
        int sock, error;
        int flags;

        sock = -1;

        nvl = nvlist_create(channel_nvlist_flags(chan));
        nvlist_add_string(nvl, "cmd", "open");
        nvlist_add_string(nvl, "service", name);
        nvl = cap_xfer_nvlist(chan, nvl);
        if (nvl == NULL)
                return (NULL);
        error = (int)nvlist_get_number(nvl, "error");
        if (error != 0) {
                nvlist_destroy(nvl);
                errno = error;
                return (NULL);
        }
        sock = nvlist_take_descriptor(nvl, "chanfd");
        flags = nvlist_take_number(nvl, "chanflags");
        assert(sock >= 0);
        nvlist_destroy(nvl);
        nvl = NULL;
        newchan = cap_wrap(sock, flags);
        if (newchan == NULL)
                goto fail;
        return (newchan);
fail:
        error = errno;
        close(sock);
        errno = error;
        return (NULL);
}

int
cap_service_limit(const cap_channel_t *chan, const char * const *names,
    size_t nnames)
{
        nvlist_t *limits;
        unsigned int i;

        limits = nvlist_create(channel_nvlist_flags(chan));
        for (i = 0; i < nnames; i++)
                nvlist_add_null(limits, names[i]);
        return (cap_limit_set(chan, limits));
}