/*      $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

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