/* Copyright (c) 2001, Adam Dunkels. All rights reserved. * * Redistribution or modification is prohibited. * * 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.   * */#include "dev.h"#include "miniweb.h"#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 <net/if_tun.h>static int drop = 0;static int fd;static int bytes_left;static char inbuf[2048], outbuf[2048];static int inptr, outptr;struct tcpip_hdr {  unsigned char vhl,    tos,              len[2],           id[2],            ipoffset[2],      ttl,              proto;       unsigned short ipchksum;  unsigned long srcipaddr,     destipaddr;  unsigned char srcport[2],    destport[2],    seqno[4],      ackno[4],    tcpoffset,    flags,    wnd[2],         tcpchksum[2],    urgp[2];   unsigned char data[0];};/*-----------------------------------------------------------------------------------*/static unsigned shortchksum(void *data, int len){  unsigned short *sdata = data;  unsigned short acc;  unsigned int sum;      for(acc = 0; len > 1; len -= 2) {    acc += *sdata++;  }  /* add up any odd byte */  if(len == 1) {    acc += (unsigned short)(*(unsigned char *)sdata);  }  sum = (acc & 0xffff) + (acc >> 16);  sum += (sum >> 16);    return ~(sum & 0xffff);}/*-----------------------------------------------------------------------------------*/static unsigned shortchksum_pseudo(void *data, int len, unsigned long ipaddr1,              unsigned long ipaddr2,              unsigned char proto,              unsigned short protolen){  unsigned int sum;  unsigned short *sdata = data;    for(sum = 0; len > 1; len -= 2) {    sum += *sdata++;  }  /* add up any odd byte */  if(len == 1) {    sum += (unsigned short)(*(unsigned char *)sdata);  }  sum += (ipaddr1 & 0xffff);  sum += ((ipaddr1 >> 16) & 0xffff);  sum += (ipaddr2 & 0xffff);  sum += ((ipaddr2 >> 16) & 0xffff);  sum += (unsigned short)htons((unsigned short)proto);  sum += (unsigned short)htons(protolen);    while(sum >> 16) {    sum = (sum & 0xffff) + (sum >> 16);  }    return ~sum & 0xffff;}/*-----------------------------------------------------------------------------------*/static voidcheck_checksum(void *data, int len){  struct tcpip_hdr *hdr;  unsigned short sum;    hdr = data;  sum = chksum(data, 20);    printf("IP header checksum check 0x%x\n", sum);    sum = chksum_pseudo(&(hdr->srcport[0]), len - 20,                      hdr->srcipaddr, hdr->destipaddr,                      hdr->proto, len - 20);    printf("TCP checksum check 0x%x len %d protolen %d\n", sum, len,         len - 20);  }/*-----------------------------------------------------------------------------------*/voiddev_init(void){  int val;  fd = open("/dev/tun0", O_RDWR);  if(fd == -1) {    perror("tun_dev: dev_init: open");    exit(1);  }#ifdef linux  system("ifconfig tun0 inet 192.168.0.2 192.168.0.1");    system("route add -net 192.168.0.0 netmask 255.255.255.0 dev tun0");#else  /*  system("ifconfig tun0 inet sidewalker rallarsnus");  */  system("ifconfig tun0 inet 192.168.0.1 192.168.0.2");#endif /* linux */  val = 0;  ioctl(fd, TUNSIFHEAD, &val);  bytes_left = 0;  outptr = 0;}/*-----------------------------------------------------------------------------------*/unsigned chardev_wait(void){  fd_set fdset;  struct timeval tv;  int ret;again:    tv.tv_sec = 0;  tv.tv_usec = 500000;  FD_ZERO(&fdset);  FD_SET(fd, &fdset);    ret = select(fd + 1, &fdset, NULL, NULL, &tv);  if(ret == 0) {    miniweb_timer();    goto again;  }   bytes_left = read(fd, inbuf, sizeof(inbuf));  if(bytes_left == -1) {    perror("tun_dev: dev_get: read");  }  /*    printf("tun_dev: dev_get: read %d bytes\n", bytes_left);*/  inptr = 0;  return dev_get();}/*-----------------------------------------------------------------------------------*/unsigned chardev_get(void){  if(bytes_left > 0) {    bytes_left--;    /*    printf("0x%02x ", (unsigned char)inbuf[inptr]); fflush(NULL);*/    return inbuf[inptr++];  }  return 0;}/*-----------------------------------------------------------------------------------*/voiddev_put(unsigned char byte){  /*  printf("0x%02x ", byte); */  outbuf[outptr++] = byte;}/*-----------------------------------------------------------------------------------*/voiddev_drop(void){  /*  printf("\n");*/  bytes_left = 0;}/*-----------------------------------------------------------------------------------*/voiddev_done(void){  int ret;    /*  check_checksum(outbuf, outptr);*/  /*  drop++;*/  if(drop % 9 == 1) {    drop = 0;    /*    printf("Dropped a packet!\n");*/    outptr = 0;    return;  }  ret = write(fd, outbuf, outptr);  if(ret == -1) {    perror("tun_dev: dev_done: write");    exit(1);  }  outptr = 0;  /*  printf("\n");*/}  /*-----------------------------------------------------------------------------------*/