/*      $NetBSD: virtif_user.c,v 1.6 2019/03/26 08:56:17 bad Exp $      */

/*
 * Copyright (c) 2013 Antti Kantee.  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 ``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/cdefs.h>
#ifdef __KERNEL_RCSID
__KERNEL_RCSID(0, "$NetBSD: virtif_user.c,v 1.6 2019/03/26 08:56:17 bad Exp $");
#endif

#ifndef _KERNEL
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/uio.h>

#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <poll.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#ifdef __linux__
#include <net/if.h>
#include <linux/if_tun.h>
#endif

#include <rump/rumpuser_component.h>

#include "if_virt.h"
#include "virtif_user.h"

#if VIFHYPER_REVISION != 20140313
#error VIFHYPER_REVISION mismatch
#endif

struct virtif_user {
        struct virtif_sc *viu_virtifsc;
        int viu_devnum;

        int viu_fd;
        int viu_pipe[2];
        pthread_t viu_rcvthr;

        int viu_dying;

        char viu_rcvbuf[9018]; /* jumbo frame max len */
};

static int
opentapdev(int devnum)
{
        int fd = -1;

#if defined(__NetBSD__) || defined(__DragonFly__)
        char tapdev[64];

        snprintf(tapdev, sizeof(tapdev), "/dev/tap%d", devnum);
        fd = open(tapdev, O_RDWR);
        if (fd == -1) {
                fprintf(stderr, "rumpcomp_virtif_create: can't open %s: "
                    "%s\n", tapdev, strerror(errno));
        }

#elif defined(__linux__)
        struct ifreq ifr;
        char devname[16];

        fd = open("/dev/net/tun", O_RDWR);
        if (fd == -1) {
                fprintf(stderr, "rumpcomp_virtif_create: can't open %s: "
                    "%s\n", "/dev/net/tun", strerror(errno));
                return -1;
        }

        snprintf(devname, sizeof(devname), "tun%d", devnum);
        memset(&ifr, 0, sizeof(ifr));
        ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
        strncpy(ifr.ifr_name, devname, sizeof(ifr.ifr_name)-1);

        if (ioctl(fd, TUNSETIFF, &ifr) == -1) {
                close(fd);
                fd = -1;
        }

#else
        fprintf(stderr, "virtif not supported on this platform\n");
#endif

        return fd;
}

static void
closetapdev(struct virtif_user *viu)
{

        close(viu->viu_fd);
}

static void *
rcvthread(void *aaargh)
{
        struct virtif_user *viu = aaargh;
        struct pollfd pfd[2];
        struct iovec iov;
        ssize_t nn = 0;
        int prv;

        rumpuser_component_kthread();

        pfd[0].fd = viu->viu_fd;
        pfd[0].events = POLLIN;
        pfd[1].fd = viu->viu_pipe[0];
        pfd[1].events = POLLIN;

        while (!viu->viu_dying) {
                prv = poll(pfd, 2, -1);
                if (prv == 0)
                        continue;
                if (prv == -1) {
                        /* XXX */
                        fprintf(stderr, "virt%d: poll error: %d\n",
                            viu->viu_devnum, errno);
                        sleep(1);
                        continue;
                }
                if (pfd[1].revents & POLLIN)
                        continue;

                nn = read(viu->viu_fd,
                    viu->viu_rcvbuf, sizeof(viu->viu_rcvbuf));
                if (nn == -1 && errno == EAGAIN)
                        continue;

                if (nn < 1) {
                        /* XXX */
                        fprintf(stderr, "virt%d: receive failed\n",
                            viu->viu_devnum);
                        sleep(1);
                        continue;
                }
                iov.iov_base = viu->viu_rcvbuf;
                iov.iov_len = nn;

                rumpuser_component_schedule(NULL);
                VIF_DELIVERPKT(viu->viu_virtifsc, &iov, 1);
                rumpuser_component_unschedule();
        }

        assert(viu->viu_dying);

        rumpuser_component_kthread_release();
        return NULL;
}

int
VIFHYPER_CREATE(const char *devstr, struct virtif_sc *vif_sc, uint8_t *enaddr,
        struct virtif_user **viup)
{
        struct virtif_user *viu = NULL;
        void *cookie;
        int devnum;
        int rv;

        cookie = rumpuser_component_unschedule();

        /*
         * Since this interface doesn't do LINKSTR, we know devstr to be
         * well-formatted.
         */
        devnum = atoi(devstr);

        viu = calloc(1, sizeof(*viu));
        if (viu == NULL) {
                rv = errno;
                goto oerr1;
        }
        viu->viu_virtifsc = vif_sc;

        viu->viu_fd = opentapdev(devnum);
        if (viu->viu_fd == -1) {
                rv = errno;
                goto oerr2;
        }
        viu->viu_devnum = devnum;

        if (pipe(viu->viu_pipe) == -1) {
                rv = errno;
                goto oerr3;
        }

        if ((rv = pthread_create(&viu->viu_rcvthr, NULL, rcvthread, viu)) != 0)
                goto oerr4;

        rumpuser_component_schedule(cookie);
        *viup = viu;
        return 0;

 oerr4:
        close(viu->viu_pipe[0]);
        close(viu->viu_pipe[1]);
 oerr3:
        closetapdev(viu);
 oerr2:
        free(viu);
 oerr1:
        rumpuser_component_schedule(cookie);
        return rumpuser_component_errtrans(rv);
}

void
VIFHYPER_SEND(struct virtif_user *viu,
        struct iovec *iov, size_t iovlen)
{
        void *cookie = rumpuser_component_unschedule();
        ssize_t idontcare __attribute__((__unused__));

        /*
         * no need to check for return value; packets may be dropped
         *
         * ... sorry, I spoke too soon.  We need to check it because
         * apparently gcc reinvented const poisoning and it's very
         * hard to say "thanks, I know I'm not using the result,
         * but please STFU and let's get on with something useful".
         * So let's trick gcc into letting us share the compiler
         * experience.
         */
        idontcare = writev(viu->viu_fd, iov, iovlen);

        rumpuser_component_schedule(cookie);
}

int
VIFHYPER_DYING(struct virtif_user *viu)
{
        void *cookie = rumpuser_component_unschedule();

        viu->viu_dying = 1;
        if (write(viu->viu_pipe[1],
            &viu->viu_dying, sizeof(viu->viu_dying)) == -1) {
                /*
                 * this is here mostly to avoid a compiler warning
                 * about ignoring the return value of write()
                 */
                fprintf(stderr, "%s: failed to signal thread\n",
                    VIF_STRING(VIFHYPER_DYING));
        }

        rumpuser_component_schedule(cookie);

        return 0;
}

void
VIFHYPER_DESTROY(struct virtif_user *viu)
{
        void *cookie = rumpuser_component_unschedule();

        pthread_join(viu->viu_rcvthr, NULL);
        closetapdev(viu);
        close(viu->viu_pipe[0]);
        close(viu->viu_pipe[1]);
        free(viu);

        rumpuser_component_schedule(cookie);
}
#endif