text: /*
   * Copyright (c) 2001-2003 Swedish Institute of Computer Science.
   * 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.
   * 3. The name of the author may not be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   *
   * 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 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.
   *
   * This file is part of the lwIP TCP/IP stack.
   *
   * Author: Adam Dunkels <adam@sics.se>
   *
   */
  
  #include <fcntl.h>
  #include <stdlib.h>
  #include <stdio.h>
  #include <unistd.h>
  #include <string.h>
  #include <sys/ioctl.h>
  #include <sys/socket.h>
  #include <sys/types.h>
  #include <sys/time.h>
  #include <sys/uio.h>
  #include <sys/socket.h>
  
  #include "lwip/opt.h"
  
  #include "lwip/debug.h"
  #include "lwip/def.h"
  #include "lwip/ip.h"
  #include "lwip/mem.h"
  #include "lwip/stats.h"
  #include "lwip/snmp.h"
  #include "lwip/pbuf.h"
  #include "lwip/sys.h"
  #include "lwip/timeouts.h"
  #include "netif/etharp.h"
  #include "lwip/ethip6.h"
  
  #include "netif/tapif.h"
  
  #define IFCONFIG_BIN "/sbin/ifconfig "
  
  #if defined(LWIP_UNIX_LINUX)
  #include <sys/ioctl.h>
  #include <linux/if.h>
  #include <linux/if_tun.h>
  /*
   * Creating a tap interface requires special privileges. If the interfaces
   * is created in advance with `tunctl -u <user>` it can be opened as a regular
   * user. The network must already be configured. If DEVTAP_IF is defined it
   * will be opened instead of creating a new tap device.
   *
   * You can also use PRECONFIGURED_TAPIF environment variable to do so.
   */
  #ifndef DEVTAP_DEFAULT_IF
  #define DEVTAP_DEFAULT_IF "tap0"
  #endif
  #ifndef DEVTAP
  #define DEVTAP "/dev/net/tun"
  #endif
  #define NETMASK_ARGS "netmask %d.%d.%d.%d"
  #define IFCONFIG_ARGS "tap0 inet %d.%d.%d.%d " NETMASK_ARGS
  #elif defined(LWIP_UNIX_OPENBSD)
  #define DEVTAP "/dev/tun0"
  #define NETMASK_ARGS "netmask %d.%d.%d.%d"
  #define IFCONFIG_ARGS "tun0 inet %d.%d.%d.%d " NETMASK_ARGS " link0"
  #else /* others */
  #define DEVTAP "/dev/tap0"
  #define NETMASK_ARGS "netmask %d.%d.%d.%d"
  #define IFCONFIG_ARGS "tap0 inet %d.%d.%d.%d " NETMASK_ARGS
  #endif
  
  /* Define those to better describe your network interface. */
  #define IFNAME0 't'
  #define IFNAME1 'p'
  
  #ifndef TAPIF_DEBUG
  #define TAPIF_DEBUG LWIP_DBG_OFF
  #endif
  
  struct tapif {
    /* Add whatever per-interface state that is needed here. */
    int fd;
  };
  
  /* Forward declarations. */
  static void tapif_input(struct netif *netif);
  #if !NO_SYS
  static void tapif_thread(void *arg);
  #endif /* !NO_SYS */
  
  /*-----------------------------------------------------------------------------------*/
  static void
  low_level_init(struct netif *netif)
  {
    struct tapif *tapif;
  #if LWIP_IPV4
    int ret;
    char buf[1024];
  #endif /* LWIP_IPV4 */
    char *preconfigured_tapif = getenv("PRECONFIGURED_TAPIF");
    
    tapif = (struct tapif *)netif->state;
  
    /* Obtain MAC address from network interface. */
  
    /* (We just fake an address...) */
    netif->hwaddr[0] = 0x02;
    netif->hwaddr[1] = 0x12;
    netif->hwaddr[2] = 0x34;
    netif->hwaddr[3] = 0x56;
    netif->hwaddr[4] = 0x78;
    netif->hwaddr[5] = 0xab;
    netif->hwaddr_len = 6;
  
    /* device capabilities */
    netif->flags = NETIF_FLAG_BROADCAST | NETIF_FLAG_ETHARP | NETIF_FLAG_IGMP;
  
    tapif->fd = open(DEVTAP, O_RDWR);
    LWIP_DEBUGF(TAPIF_DEBUG, ("tapif_init: fd %d\n", tapif->fd));
    if (tapif->fd == -1) {
  #ifdef LWIP_UNIX_LINUX
      perror("tapif_init: try running \"modprobe tun\" or rebuilding your kernel with CONFIG_TUN; cannot open "DEVTAP);
  #else /* LWIP_UNIX_LINUX */
      perror("tapif_init: cannot open "DEVTAP);
  #endif /* LWIP_UNIX_LINUX */
      exit(1);
    }
  
  #ifdef LWIP_UNIX_LINUX
    {
      struct ifreq ifr;
      memset(&ifr, 0, sizeof(ifr));
  
      if (preconfigured_tapif) {
        strncpy(ifr.ifr_name, preconfigured_tapif, sizeof(ifr.ifr_name));
      } else {
        strncpy(ifr.ifr_name, DEVTAP_DEFAULT_IF, sizeof(ifr.ifr_name));
      } 
      ifr.ifr_name[sizeof(ifr.ifr_name)-1] = 0; /* ensure \0 termination */
  
      ifr.ifr_flags = IFF_TAP|IFF_NO_PI;
      if (ioctl(tapif->fd, TUNSETIFF, (void *) &ifr) < 0) {
        perror("tapif_init: "DEVTAP" ioctl TUNSETIFF");
        exit(1);
      }
    }
  #endif /* LWIP_UNIX_LINUX */
  
    netif_set_link_up(netif);
  
    if (preconfigured_tapif == NULL) {
  #if LWIP_IPV4
      snprintf(buf, 1024, IFCONFIG_BIN IFCONFIG_ARGS,
               ip4_addr1(netif_ip4_gw(netif)),
               ip4_addr2(netif_ip4_gw(netif)),
               ip4_addr3(netif_ip4_gw(netif)),
               ip4_addr4(netif_ip4_gw(netif))
  #ifdef NETMASK_ARGS
               ,
               ip4_addr1(netif_ip4_netmask(netif)),
               ip4_addr2(netif_ip4_netmask(netif)),
               ip4_addr3(netif_ip4_netmask(netif)),
               ip4_addr4(netif_ip4_netmask(netif))
  #endif /* NETMASK_ARGS */
               );
  
      LWIP_DEBUGF(TAPIF_DEBUG, ("tapif_init: system(\"%s\");\n", buf));
      ret = system(buf);
      if (ret < 0) {
        perror("ifconfig failed");
        exit(1);
      }
      if (ret != 0) {
        printf("ifconfig returned %d\n", ret);
      }
  #else /* LWIP_IPV4 */
      perror("todo: support IPv6 support for non-preconfigured tapif");
      exit(1);
  #endif /* LWIP_IPV4 */
    }
  
  #if !NO_SYS
    sys_thread_new("tapif_thread", tapif_thread, netif, DEFAULT_THREAD_STACKSIZE, DEFAULT_THREAD_PRIO);
  #endif /* !NO_SYS */
  }
  /*-----------------------------------------------------------------------------------*/
  /*
   * low_level_output():
   *
   * Should do the actual transmission of the packet. The packet is
   * contained in the pbuf that is passed to the function. This pbuf
   * might be chained.
   *
   */
  /*-----------------------------------------------------------------------------------*/
  
  static err_t
  low_level_output(struct netif *netif, struct pbuf *p)
  {
    struct tapif *tapif = (struct tapif *)netif->state;
    char buf[1518]; /* max packet size including VLAN excluding CRC */
    ssize_t written;
  
  #if 0
    if (((double)rand()/(double)RAND_MAX) < 0.2) {
      printf("drop output\n");
      return ERR_OK; /* ERR_OK because we simulate packet loss on cable */
    }
  #endif
  
    if (p->tot_len > sizeof(buf)) {
      MIB2_STATS_NETIF_INC(netif, ifoutdiscards);
      perror("tapif: packet too large");
      return ERR_IF;
    }
  
    /* initiate transfer(); */
    pbuf_copy_partial(p, buf, p->tot_len, 0);
  
    /* signal that packet should be sent(); */
    written = write(tapif->fd, buf, p->tot_len);
    if (written < p->tot_len) {
      MIB2_STATS_NETIF_INC(netif, ifoutdiscards);
      perror("tapif: write");
      return ERR_IF;
    } else {
      MIB2_STATS_NETIF_ADD(netif, ifoutoctets, (u32_t)written);
      return ERR_OK;
    }
  }
  /*-----------------------------------------------------------------------------------*/
  /*
   * low_level_input():
   *
   * Should allocate a pbuf and transfer the bytes of the incoming
   * packet from the interface into the pbuf.
   *
   */
  /*-----------------------------------------------------------------------------------*/
  static struct pbuf *
  low_level_input(struct netif *netif)
  {
    struct pbuf *p;
    u16_t len;
    ssize_t readlen;
    char buf[1518]; /* max packet size including VLAN excluding CRC */
    struct tapif *tapif = (struct tapif *)netif->state;
  
    /* Obtain the size of the packet and put it into the "len"
       variable. */
    readlen = read(tapif->fd, buf, sizeof(buf));
    if (readlen < 0) {
      perror("read returned -1");
      exit(1);
    }
    len = (u16_t)readlen;
  
    MIB2_STATS_NETIF_ADD(netif, ifinoctets, len);
  
  #if 0
    if (((double)rand()/(double)RAND_MAX) < 0.2) {
      printf("drop\n");
      return NULL;
    }
  #endif
  
    /* We allocate a pbuf chain of pbufs from the pool. */
    p = pbuf_alloc(PBUF_RAW, len, PBUF_POOL);
    if (p != NULL) {
      pbuf_take(p, buf, len);
      /* acknowledge that packet has been read(); */
    } else {
      /* drop packet(); */
      MIB2_STATS_NETIF_INC(netif, ifindiscards);
      LWIP_DEBUGF(NETIF_DEBUG, ("tapif_input: could not allocate pbuf\n"));
    }
  
    return p;
  }
  
  /*-----------------------------------------------------------------------------------*/
  /*
   * tapif_input():
   *
   * This function should be called when a packet is ready to be read
   * from the interface. It uses the function low_level_input() that
   * should handle the actual reception of bytes from the network
   * interface.
   *
   */
  /*-----------------------------------------------------------------------------------*/
  static void
  tapif_input(struct netif *netif)
  {
    struct pbuf *p = low_level_input(netif);
  
    if (p == NULL) {
  #if LINK_STATS
      LINK_STATS_INC(link.recv);
  #endif /* LINK_STATS */
      LWIP_DEBUGF(TAPIF_DEBUG, ("tapif_input: low_level_input returned NULL\n"));
      return;
    }
  
    if (netif->input(p, netif) != ERR_OK) {
      LWIP_DEBUGF(NETIF_DEBUG, ("tapif_input: netif input error\n"));
      pbuf_free(p);
    }
  }
  /*-----------------------------------------------------------------------------------*/
  /*
   * tapif_init():
   *
   * Should be called at the beginning of the program to set up the
   * network interface. It calls the function low_level_init() to do the
   * actual setup of the hardware.
   *
   */
  /*-----------------------------------------------------------------------------------*/
  err_t
  tapif_init(struct netif *netif)
  {
    struct tapif *tapif = (struct tapif *)mem_malloc(sizeof(struct tapif));
  
    if (tapif == NULL) {
      LWIP_DEBUGF(NETIF_DEBUG, ("tapif_init: out of memory for tapif\n"));
      return ERR_MEM;
    }
    netif->state = tapif;
    MIB2_INIT_NETIF(netif, snmp_ifType_other, 100000000);
  
    netif->name[0] = IFNAME0;
    netif->name[1] = IFNAME1;
  #if LWIP_IPV4
    netif->output = etharp_output;
  #endif /* LWIP_IPV4 */
  #if LWIP_IPV6
    netif->output_ip6 = ethip6_output;
  #endif /* LWIP_IPV6 */
    netif->linkoutput = low_level_output;
    netif->mtu = 1500;
  
    low_level_init(netif);
  
    return ERR_OK;
  }
  
  
  /*-----------------------------------------------------------------------------------*/
  void
  tapif_poll(struct netif *netif)
  {
    tapif_input(netif);
  }
  
  #if NO_SYS
  
  int
  tapif_select(struct netif *netif)
  {
    fd_set fdset;
    int ret;
    struct timeval tv;
    struct tapif *tapif;
    u32_t msecs = sys_timeouts_sleeptime();
  
    tapif = (struct tapif *)netif->state;
  
    tv.tv_sec = msecs / 1000;
    tv.tv_usec = (msecs % 1000) * 1000;
  
    FD_ZERO(&fdset);
    FD_SET(tapif->fd, &fdset);
  
    ret = select(tapif->fd + 1, &fdset, NULL, NULL, &tv);
    if (ret > 0) {
      tapif_input(netif);
    }
    return ret;
  }
  
  #else /* NO_SYS */
  
  static void
  tapif_thread(void *arg)
  {
    struct netif *netif;
    struct tapif *tapif;
    fd_set fdset;
    int ret;
  
    netif = (struct netif *)arg;
    tapif = (struct tapif *)netif->state;
  
    while(1) {
      FD_ZERO(&fdset);
      FD_SET(tapif->fd, &fdset);
  
      /* Wait for a packet to arrive. */
      ret = select(tapif->fd + 1, &fdset, NULL, NULL, NULL);
  
      if(ret == 1) {
        /* Handle incoming packet. */
        tapif_input(netif);
      } else if(ret == -1) {
        perror("tapif_thread: select");
      }
    }
  }
  
  #endif /* NO_SYS */
  