contrib/ipfilter/relay.c

   1 /*
   2  * Sample program to be used as a transparent proxy.
   3  *
   4  * Must be executed with permission enough to do an ioctl on /dev/ipl
   5  * or equivalent.  This is just a sample and is only alpha quality.
   6  * - Darren Reed (8 April 1996)
   7  */
   8 #include <unistd.h>
   9 #include <stdio.h>
  10 #include <fcntl.h>
  11 #include <sys/types.h>
  12 #include <sys/time.h>
  13 #include <sys/errno.h>
  14 #include <sys/syslog.h>
  15 #include <sys/ioctl.h>
  16 #include <netinet/in.h>
  17 #include <net/if.h>
  18 #include <sys/socket.h>
  19 #include "ip_nat.h"
  20
  21 #define RELAY_BUFSZ     8192
  22
  23 char    ibuff[RELAY_BUFSZ];
  24 char    obuff[RELAY_BUFSZ];
  25
  26 int relay(ifd, ofd, rfd)
  27 int ifd, ofd, rfd;
  28 {
  29         fd_set  rfds, wfds;
  30         char    *irh, *irt, *rrh, *rrt;
  31         char    *iwh, *iwt, *rwh, *rwt;
  32         int     nfd, n, rw;
  33
  34         irh = irt = ibuff;
  35         iwh = iwt = obuff;
  36         nfd = ifd;
  37         if (nfd < ofd)
  38                 nfd = ofd;
  39         if (nfd < rfd)
  40                 nfd = rfd;
  41
  42         while (1) {
  43                 FD_ZERO(&rfds);
  44                 FD_ZERO(&wfds);
  45                 if (irh > irt)
  46                         FD_SET(rfd, &wfds);
  47                 if (irh < (ibuff + RELAY_BUFSZ))
  48                         FD_SET(ifd, &rfds);
  49                 if (iwh > iwt)
  50                         FD_SET(ofd, &wfds);
  51                 if (iwh < (obuff + RELAY_BUFSZ))
  52                         FD_SET(rfd, &rfds);
  53
  54                 switch ((n = select(nfd + 1, &rfds, &wfds, NULL, NULL)))
  55                 {
  56                 case -1 :
  57                 case 0 :
  58                         return -1;
  59                 default :
  60                         if (FD_ISSET(ifd, &rfds)) {
  61                                 rw = read(ifd, irh, ibuff + RELAY_BUFSZ - irh);
  62                                 if (rw == -1)
  63                                         return -1;
  64                                 if (rw == 0)
  65                                         return 0;
  66                                 irh += rw;
  67                                 n--;
  68                         }
  69                         if (n && FD_ISSET(ofd, &wfds)) {
  70                                 rw = write(ofd, iwt, iwh  - iwt);
  71                                 if (rw == -1)
  72                                         return -1;
  73                                 iwt += rw;
  74                                 n--;
  75                         }
  76                         if (n && FD_ISSET(rfd, &rfds)) {
  77                                 rw = read(rfd, iwh, obuff + RELAY_BUFSZ - iwh);
  78                                 if (rw == -1)
  79                                         return -1;
  80                                 if (rw == 0)
  81                                         return 0;
  82                                 iwh += rw;
  83                                 n--;
  84                         }
  85                         if (n && FD_ISSET(rfd, &wfds)) {
  86                                 rw = write(rfd, irt, irh  - irt);
  87                                 if (rw == -1)
  88                                         return -1;
  89                                 irt += rw;
  90                                 n--;
  91                         }
  92                         if (irh == irt)
  93                                 irh = irt = ibuff;
  94                         if (iwh == iwt)
  95                                 iwh = iwt = obuff;
  96                 }
  97         }
  98 }
  99
 100 main(argc, argv)
 101 int argc;
 102 char *argv[];
 103 {
 104         struct  sockaddr_in     sin;
 105         natlookup_t     nl;
 106         natlookup_t     *nlp = &nl;
 107         int     fd, sl = sizeof(sl), se;
 108
 109         openlog(argv[0], LOG_PID|LOG_NDELAY, LOG_DAEMON);
 110         if ((fd = open("/dev/ipnat", O_RDONLY)) == -1) {
 111                 se = errno;
 112                 perror("open");
 113                 errno = se;
 114                 syslog(LOG_ERR, "open: %m\n");
 115                 exit(-1);
 116         }
 117
 118         bzero(&nl, sizeof(nl));
 119         nl.nl_flags = IPN_TCP;
 120
 121         bzero(&sin, sizeof(sin));
 122         sin.sin_family = AF_INET;
 123         sl = sizeof(sin);
 124         if (getsockname(0, (struct sockaddr *)&sin, &sl) == -1) {
 125                 se = errno;
 126                 perror("getsockname");
 127                 errno = se;
 128                 syslog(LOG_ERR, "getsockname: %m\n");
 129                 exit(-1);
 130         } else {
 131                 nl.nl_inip.s_addr = sin.sin_addr.s_addr;
 132                 nl.nl_inport = sin.sin_port;
 133         }
 134
 135         bzero(&sin, sizeof(sin));
 136         sin.sin_family = AF_INET;
 137         sl = sizeof(sin);
 138         if (getpeername(0, (struct sockaddr *)&sin, &sl) == -1) {
 139                 se = errno;
 140                 perror("getpeername");
 141                 errno = se;
 142                 syslog(LOG_ERR, "getpeername: %m\n");
 143                 exit(-1);
 144         } else {
 145                 nl.nl_outip.s_addr = sin.sin_addr.s_addr;
 146                 nl.nl_outport = sin.sin_port;
 147         }
 148
 149         if (ioctl(fd, SIOCGNATL, &nlp) == -1) {
 150                 se = errno;
 151                 perror("ioctl");
 152                 errno = se;
 153                 syslog(LOG_ERR, "ioctl: %m\n");
 154                 exit(-1);
 155         }
 156
 157         sin.sin_port = nl.nl_realport;
 158         sin.sin_addr = nl.nl_realip;
 159         sl = sizeof(sin);
 160
 161         fd = socket(AF_INET, SOCK_STREAM, 0);
 162         if (connect(fd, (struct sockaddr *)&sin, sl) == -1) {
 163                 se = errno;
 164                 perror("connect");
 165                 errno = se;
 166                 syslog(LOG_ERR, "connect: %m\n");
 167                 exit(-1);
 168         }
 169
 170         (void) ioctl(fd, F_SETFL, ioctl(fd, F_GETFL, 0)|O_NONBLOCK);
 171         (void) ioctl(0, F_SETFL, ioctl(fd, F_GETFL, 0)|O_NONBLOCK);
 172         (void) ioctl(1, F_SETFL, ioctl(fd, F_GETFL, 0)|O_NONBLOCK);
 173
 174         syslog(LOG_NOTICE, "connected to %s,%d\n", inet_ntoa(sin.sin_addr),
 175                 ntohs(sin.sin_port));
 176         if (relay(0, 1, fd) == -1) {
 177                 se = errno;
 178                 perror("relay");
 179                 errno = se;
 180                 syslog(LOG_ERR, "relay: %m\n");
 181                 exit(-1);
 182         }
 183         exit(0);
 184 }