tun.c

tun虚拟网卡设备源码

#else

void
open_tun (const char *dev, const char *dev_type, const char *dev_node, bool ipv6, struct tuntap *tt)
{
  ASSERT (0);
}

#endif

#else

void
open_tun (const char *dev, const char *dev_type, const char *dev_node, bool ipv6, struct tuntap *tt)
{
  open_tun_generic (dev, dev_type, dev_node, ipv6, false, true, tt);
}

#endif /* HAVE_LINUX_IF_TUN_H */

#ifdef TUNSETPERSIST

void
tuncfg (const char *dev, const char *dev_type, const char *dev_node, bool ipv6, int persist_mode)
{
  struct tuntap *tt;

  ALLOC_OBJ (tt, struct tuntap);
  clear_tuntap (tt);
  tt->type = dev_type_enum (dev, dev_type);
  open_tun (dev, dev_type, dev_node, ipv6, tt);
  if (ioctl (tt->fd, TUNSETPERSIST, persist_mode) < 0)
    msg (M_ERR, "Cannot ioctl TUNSETPERSIST(%d) %s", persist_mode, dev);
  close_tun (tt);
  msg (M_INFO, "Persist state set to: %s", (persist_mode ? "ON" : "OFF"));
}

#endif /* TUNSETPERSIST */

void
close_tun (struct tuntap *tt)
{
  if (tt)
    {
      close_tun_generic (tt);
      free (tt);
    }
}

int
write_tun (struct tuntap* tt, uint8_t *buf, int len)
{
#if LINUX_IPV6
  if (tt->ipv6)
    {
      struct tun_pi pi;
      struct iphdr *iph;
      struct iovec vect[2];
      int ret;

      iph = (struct iphdr *)buf;

      pi.flags = 0;

      if(iph->version == 6)
	pi.proto = htons(ETH_P_IPV6);
      else
	pi.proto = htons(ETH_P_IP);

      vect[0].iov_len = sizeof(pi);
      vect[0].iov_base = &pi;
      vect[1].iov_len = len;
      vect[1].iov_base = buf;

      ret = writev(tt->fd, vect, 2);
      return(ret - sizeof(pi));
    }
  else
#endif
    return write (tt->fd, buf, len);
}

int
read_tun (struct tuntap* tt, uint8_t *buf, int len)
{
#if LINUX_IPV6
  if (tt->ipv6)
    {
      struct iovec vect[2];
      struct tun_pi pi;
      int ret;

      vect[0].iov_len = sizeof(pi);
      vect[0].iov_base = &pi;
      vect[1].iov_len = len;
      vect[1].iov_base = buf;

      ret = readv(tt->fd, vect, 2);
      return(ret - sizeof(pi));
    }
  else
#endif
    return read (tt->fd, buf, len);
}

#elif defined(TARGET_SOLARIS)

#ifndef TUNNEWPPA
#error I need the symbol TUNNEWPPA from net/if_tun.h
#endif

void
open_tun (const char *dev, const char *dev_type, const char *dev_node, bool ipv6, struct tuntap *tt)
{
  int if_fd, muxid, ppa = -1;
  struct ifreq ifr;
  const char *ptr;
  const char *ip_node;
  const char *dev_tuntap_type;
  int link_type;
  bool is_tun;

  ipv6_support (ipv6, false, tt);

  if (tt->type == DEV_TYPE_NULL)
    {
      open_null (tt);
      return;
    }

  if (tt->type == DEV_TYPE_TUN)
    {
      ip_node = "/dev/udp";
      if (!dev_node)
	dev_node = "/dev/tun";
      dev_tuntap_type = "tun";
      link_type = I_PLINK;
      is_tun = true;
    }
  else if (tt->type == DEV_TYPE_TAP)
    {
      ip_node = "/dev/ip";
      if (!dev_node)
	dev_node = "/dev/tap";
      dev_tuntap_type = "tap";
      link_type = I_PLINK; /* was: I_LINK */
      is_tun = false;
    }
  else
    {
      msg (M_FATAL, "I don't recognize device %s as a tun or tap device",
	   dev);
    }
  
  /* get unit number */
  if (*dev)
    {
      ptr = dev;
      while (*ptr && !isdigit ((int) *ptr))
	ptr++;
      ppa = atoi (ptr);
    }

  if ((tt->ip_fd = open (ip_node, O_RDWR, 0)) < 0)
    msg (M_ERR, "Can't open %s", ip_node);

  if ((tt->fd = open (dev_node, O_RDWR, 0)) < 0)
    msg (M_ERR, "Can't open %s", dev_node);

  /* Assign a new PPA and get its unit number. */
  if ((ppa = ioctl (tt->fd, TUNNEWPPA, ppa)) < 0)
    msg (M_ERR, "Can't assign new interface");

  if ((if_fd = open (dev_node, O_RDWR, 0)) < 0)
    msg (M_ERR, "Can't open %s (2)", dev_node);

  if (ioctl (if_fd, I_PUSH, "ip") < 0)
    msg (M_ERR, "Can't push IP module");

  /* Assign ppa according to the unit number returned by tun device */
  if (ioctl (if_fd, IF_UNITSEL, (char *) &ppa) < 0)
    msg (M_ERR, "Can't set PPA %d", ppa);

  if ((muxid = ioctl (tt->ip_fd, link_type, if_fd)) < 0)
    msg (M_ERR, "Can't link %s device to IP", dev_tuntap_type);

  close (if_fd);

  tt->actual_name = (char *) malloc (32);
  check_malloc_return (tt->actual_name);

  openvpn_snprintf (tt->actual_name, 32, "%s%d", dev_tuntap_type, ppa);

  CLEAR (ifr);
  strncpynt (ifr.ifr_name, tt->actual_name, sizeof (ifr.ifr_name));
  ifr.ifr_ip_muxid = muxid;

  if (ioctl (tt->ip_fd, SIOCSIFMUXID, &ifr) < 0)
    {
      ioctl (tt->ip_fd, I_PUNLINK, muxid);
      msg (M_ERR, "Can't set multiplexor id");
    }

  set_nonblock (tt->fd);
  set_cloexec (tt->fd);
  set_cloexec (tt->ip_fd);

  msg (M_INFO, "TUN/TAP device %s opened", tt->actual_name);
}

static void
solaris_close_tun (struct tuntap *tt)
{
  if (tt)
    {
      if (tt->ip_fd >= 0)
	{
	  struct ifreq ifr;
	  CLEAR (ifr);
	  strncpynt (ifr.ifr_name, tt->actual_name, sizeof (ifr.ifr_name));

	  if (ioctl (tt->ip_fd, SIOCGIFFLAGS, &ifr) < 0)
	    msg (M_WARN | M_ERRNO, "Can't get iface flags");

	  if (ioctl (tt->ip_fd, SIOCGIFMUXID, &ifr) < 0)
	    msg (M_WARN | M_ERRNO, "Can't get multiplexor id");

	  if (ioctl (tt->ip_fd, I_PUNLINK, ifr.ifr_ip_muxid) < 0)
	    msg (M_WARN | M_ERRNO, "Can't unlink interface");

	  close (tt->ip_fd);
	  tt->ip_fd = -1;
	}

      if (tt->fd >= 0)
	{
	  close (tt->fd);
	  tt->fd = -1;
	}
    }
}

/*
 * Close TUN device. 
 */
void
close_tun (struct tuntap *tt)
{
  if (tt)
    {
      solaris_close_tun (tt);

      if (tt->actual_name)
	free (tt->actual_name);
      
      clear_tuntap (tt);
      free (tt);
    }
}

static void
solaris_error_close (struct tuntap *tt, const struct env_set *es, const char *actual)
{
  char command_line[256];

  openvpn_snprintf (command_line, sizeof (command_line),
		    IFCONFIG_PATH " %s unplumb",
		    actual);

  msg (M_INFO, "%s", command_line);
  system_check (command_line, es, 0, "Solaris ifconfig unplumb failed");
  close_tun (tt);
  msg (M_FATAL, "Solaris ifconfig failed");
}

int
write_tun (struct tuntap* tt, uint8_t *buf, int len)
{
  struct strbuf sbuf;
  sbuf.len = len;
  sbuf.buf = (char *)buf;
  return putmsg (tt->fd, NULL, &sbuf, 0) >= 0 ? sbuf.len : -1;
}

int
read_tun (struct tuntap* tt, uint8_t *buf, int len)
{
  struct strbuf sbuf;
  int f = 0;

  sbuf.maxlen = len;
  sbuf.buf = (char *)buf;
  return getmsg (tt->fd, NULL, &sbuf, &f) >= 0 ? sbuf.len : -1;
}

#elif defined(TARGET_OPENBSD)

#if !defined(HAVE_READV) || !defined(HAVE_WRITEV)
#error openbsd build requires readv & writev library functions
#endif

/*
 * OpenBSD has a slightly incompatible TUN device from
 * the rest of the world, in that it prepends a
 * uint32 to the beginning of the IP header
 * to designate the protocol (why not just
 * look at the version field in the IP header to
 * determine v4 or v6?).
 *
 * We strip off this field on reads and
 * put it back on writes.
 *
 * I have not tested TAP devices on OpenBSD,
 * but I have conditionalized the special
 * TUN handling code described above to
 * go away for TAP devices.
 */

void
open_tun (const char *dev, const char *dev_type, const char *dev_node, bool ipv6, struct tuntap *tt)
{
  open_tun_generic (dev, dev_type, dev_node, ipv6, true, true, tt);

  /* Enable multicast on the interface */
  if (tt->fd >= 0)
    {
      struct tuninfo info;

      if (ioctl (tt->fd, TUNGIFINFO, &info) < 0) {
	msg (M_WARN | M_ERRNO, "Can't get interface info: %s",
	  strerror(errno));
      }

      info.flags |= IFF_MULTICAST;

      if (ioctl (tt->fd, TUNSIFINFO, &info) < 0) {
	msg (M_WARN | M_ERRNO, "Can't set interface info: %s",
	  strerror(errno));
      }
    }
}

void
close_tun (struct tuntap* tt)
{
  if (tt)
    {
      close_tun_generic (tt);
      free (tt);
    }
}

static inline int
openbsd_modify_read_write_return (int len)
{
 if (len > 0)
    return len > sizeof (u_int32_t) ? len - sizeof (u_int32_t) : 0;
  else
    return len;
}

int
write_tun (struct tuntap* tt, uint8_t *buf, int len)
{
  if (tt->type == DEV_TYPE_TUN)
    {
      u_int32_t type;
      struct iovec iv[2];
      struct ip *iph;

      iph = (struct ip *) buf;

      if (tt->ipv6 && iph->ip_v == 6)
	type = htonl (AF_INET6);
      else 
	type = htonl (AF_INET);

      iv[0].iov_base = &type;
      iv[0].iov_len = sizeof (type);
      iv[1].iov_base = buf;
      iv[1].iov_len = len;

      return openbsd_modify_read_write_return (writev (tt->fd, iv, 2));
    }
  else
    return write (tt->fd, buf, len);
}

int
read_tun (struct tuntap* tt, uint8_t *buf, int len)
{
  if (tt->type == DEV_TYPE_TUN)
    {
      u_int32_t type;
      struct iovec iv[2];

      iv[0].iov_base = &type;
      iv[0].iov_len = sizeof (type);
      iv[1].iov_base = buf;
      iv[1].iov_len = len;

      return openbsd_modify_read_write_return (readv (tt->fd, iv, 2));
    }
  else
    return read (tt->fd, buf, len);
}

#elif defined(TARGET_NETBSD)

/*
 * NetBSD does not support IPv6 on tun out of the box,
 * but there exists a patch. When this patch is applied,
 * only two things are left to openvpn:
 * 1. Activate multicasting (this has already been done
 *    before by the kernel, but we make sure that nobody
 *    has deactivated multicasting inbetween.
 * 2. Deactivate "link layer mode" (otherwise NetBSD 
 *    prepends the address family to the packet, and we
 *    would run into the same trouble as with OpenBSD.
 */

void
open_tun (const char *dev, const char *dev_type, const char *dev_node, bool ipv6, struct tuntap *tt)
{
    open_tun_generic (dev, dev_type, dev_node, ipv6, true, true, tt);
    if (tt->fd >= 0)
      {
        int i = IFF_POINTOPOINT|IFF_MULTICAST;
        ioctl (tt->fd, TUNSIFMODE, &i);  /* multicast on */
        i = 0;
        ioctl (tt->fd, TUNSLMODE, &i);   /* link layer mode off */
      }
}

void
close_tun (struct tuntap *tt)
{
  if (tt)
    {
      close_tun_generic (tt);
      free (tt);
    }
}

int
write_tun (struct tuntap* tt, uint8_t *buf, int len)
{
    return write (tt->fd, buf, len);
}

int
read_tun (struct tuntap* tt, uint8_t *buf, int len)
{
    return read (tt->fd, buf, len);
}

#elif defined(TARGET_FREEBSD)

static inline int
freebsd_modify_read_write_return (int len)
{
  if (len > 0)
    return len > sizeof (u_int32_t) ? len - sizeof (u_int32_t) : 0;
  else
    return len;
}

void
open_tun (const char *dev, const char *dev_type, const char *dev_node, bool ipv6, struct tuntap *tt)
{
  open_tun_generic (dev, dev_type, dev_node, ipv6, true, true, tt);

  if (tt->fd >= 0)
    {
      int i = 0;

      /* Disable extended modes */
      ioctl (tt->fd, TUNSLMODE, &i);
      i = 1;
      ioctl (tt->fd, TUNSIFHEAD, &i);
    }
}

void
close_tun (struct tuntap *tt)
{
  if (tt)
    {
      close_tun_generic (tt);
      free (tt);
    }
}

int
write_tun (struct tuntap* tt, uint8_t *buf, int len)
{
  if (tt->type == DEV_TYPE_TUN)
    {
      u_int32_t type;
      struct iovec iv[2];
      struct ip *iph;

      iph = (struct ip *) buf;

      if (tt->ipv6 && iph->ip_v == 6)
        type = htonl (AF_INET6);
      else 
        type = htonl (AF_INET);

      iv[0].iov_base = (char *)&type;
      iv[0].iov_len = sizeof (type);
      iv[1].iov_base = buf;
      iv[1].iov_len = len;

      return freebsd_modify_read_write_return (writev (tt->fd, iv, 2));
    }
  else
    return write (tt->fd, buf, len);
}

int
read_tun (struct tuntap* tt, uint8_t *buf, int len)
{
  if (tt->type == DEV_TYPE_TUN)
    {
      u_int32_t type;
      struct iovec iv[2];

      iv[0].iov_base = (char *)&type;
      iv[0].iov_len = sizeof (type);
      iv[1].iov_base = buf;
      iv[1].iov_len = len;

      return freebsd_modify_read_write_return (readv (tt->fd, iv, 2));
    }
  else
    return read (tt->fd, buf, len);