1 2/* 3 * Sample program to be used as a transparent proxy. 4 * 5 * Must be executed with permission enough to do an ioctl on /dev/ipl 6 * or equivalent. This is just a sample and is only alpha quality. 7 * - Darren Reed (8 April 1996) 8 */ 9#include <unistd.h> 10#include <stdio.h> 11#include <fcntl.h> 12#include <errno.h> 13#include <sys/types.h> 14#include <sys/time.h> 15#include <sys/syslog.h> 16#include <sys/socket.h> 17#include <sys/ioctl.h> 18#include <netinet/in.h> 19#include <net/if.h> 20#include "netinet/ip_compat.h" 21#include "netinet/ip_fil.h" 22#include "netinet/ip_nat.h" 23#include "netinet/ipl.h" 24 25#define RELAY_BUFSZ 8192 26 27char ibuff[RELAY_BUFSZ]; 28char obuff[RELAY_BUFSZ]; 29 30int relay(ifd, ofd, rfd) 31 int ifd, ofd, rfd; 32{ 33 fd_set rfds, wfds; 34 char *irh, *irt, *rrh, *rrt; 35 char *iwh, *iwt, *rwh, *rwt; 36 int nfd, n, rw; 37 38 irh = irt = ibuff; 39 iwh = iwt = obuff; 40 nfd = ifd; 41 if (nfd < ofd) 42 nfd = ofd; 43 if (nfd < rfd) 44 nfd = rfd; 45 46 while (1) { 47 FD_ZERO(&rfds); 48 FD_ZERO(&wfds); 49 if (irh > irt) 50 FD_SET(rfd, &wfds); 51 if (irh < (ibuff + RELAY_BUFSZ)) 52 FD_SET(ifd, &rfds); 53 if (iwh > iwt) 54 FD_SET(ofd, &wfds); 55 if (iwh < (obuff + RELAY_BUFSZ)) 56 FD_SET(rfd, &rfds); 57 58 switch ((n = select(nfd + 1, &rfds, &wfds, NULL, NULL))) 59 { 60 case -1 : 61 case 0 : 62 return(-1); 63 default : 64 if (FD_ISSET(ifd, &rfds)) { 65 rw = read(ifd, irh, ibuff + RELAY_BUFSZ - irh); 66 if (rw == -1) 67 return(-1); 68 if (rw == 0) 69 return(0); 70 irh += rw; 71 n--; 72 } 73 if (n && FD_ISSET(ofd, &wfds)) { 74 rw = write(ofd, iwt, iwh - iwt); 75 if (rw == -1) 76 return(-1); 77 iwt += rw; 78 n--; 79 } 80 if (n && FD_ISSET(rfd, &rfds)) { 81 rw = read(rfd, iwh, obuff + RELAY_BUFSZ - iwh); 82 if (rw == -1) 83 return(-1); 84 if (rw == 0) 85 return(0); 86 iwh += rw; 87 n--; 88 } 89 if (n && FD_ISSET(rfd, &wfds)) { 90 rw = write(rfd, irt, irh - irt); 91 if (rw == -1) 92 return(-1); 93 irt += rw; 94 n--; 95 } 96 if (irh == irt) 97 irh = irt = ibuff; 98 if (iwh == iwt) 99 iwh = iwt = obuff; 100 } 101 } 102} 103 104main(argc, argv) 105 int argc; 106 char *argv[]; 107{ 108 struct sockaddr_in sin; 109 ipfobj_t obj; 110 natlookup_t nl; 111 natlookup_t *nlp = &nl; 112 int fd, sl = sizeof(sl), se; 113 114 openlog(argv[0], LOG_PID|LOG_NDELAY, LOG_DAEMON); 115 if ((fd = open(IPNAT_NAME, O_RDONLY)) == -1) { 116 se = errno; 117 perror("open"); 118 errno = se; 119 syslog(LOG_ERR, "open: %m\n"); 120 exit(-1); 121 } 122 123 bzero(&obj, sizeof(obj)); 124 obj.ipfo_rev = IPFILTER_VERSION; 125 obj.ipfo_size = sizeof(nl); 126 obj.ipfo_ptr = &nl; 127 obj.ipfo_type = IPFOBJ_NATLOOKUP; 128 129 bzero(&nl, sizeof(nl)); 130 nl.nl_flags = IPN_TCP; 131 132 bzero(&sin, sizeof(sin)); 133 sin.sin_family = AF_INET; 134 sl = sizeof(sin); 135 if (getsockname(0, (struct sockaddr *)&sin, &sl) == -1) { 136 se = errno; 137 perror("getsockname"); 138 errno = se; 139 syslog(LOG_ERR, "getsockname: %m\n"); 140 exit(-1); 141 } else { 142 nl.nl_inip.s_addr = sin.sin_addr.s_addr; 143 nl.nl_inport = sin.sin_port; 144 } 145 146 bzero(&sin, sizeof(sin)); 147 sin.sin_family = AF_INET; 148 sl = sizeof(sin); 149 if (getpeername(0, (struct sockaddr *)&sin, &sl) == -1) { 150 se = errno; 151 perror("getpeername"); 152 errno = se; 153 syslog(LOG_ERR, "getpeername: %m\n"); 154 exit(-1); 155 } else { 156 nl.nl_outip.s_addr = sin.sin_addr.s_addr; 157 nl.nl_outport = sin.sin_port; 158 } 159 160 if (ioctl(fd, SIOCGNATL, &obj) == -1) { 161 se = errno; 162 perror("ioctl"); 163 errno = se; 164 syslog(LOG_ERR, "ioctl: %m\n"); 165 exit(-1); 166 } 167 168 sin.sin_port = nl.nl_realport; 169 sin.sin_addr = nl.nl_realip; 170 sl = sizeof(sin); 171 172 fd = socket(AF_INET, SOCK_STREAM, 0); 173 if (connect(fd, (struct sockaddr *)&sin, sl) == -1) { 174 se = errno; 175 perror("connect"); 176 errno = se; 177 syslog(LOG_ERR, "connect: %m\n"); 178 exit(-1); 179 } 180 181 (void) ioctl(fd, F_SETFL, ioctl(fd, F_GETFL, 0)|O_NONBLOCK); 182 (void) ioctl(0, F_SETFL, ioctl(fd, F_GETFL, 0)|O_NONBLOCK); 183 (void) ioctl(1, F_SETFL, ioctl(fd, F_GETFL, 0)|O_NONBLOCK); 184 185 syslog(LOG_NOTICE, "connected to %s,%d\n", inet_ntoa(sin.sin_addr), 186 ntohs(sin.sin_port)); 187 if (relay(0, 1, fd) == -1) { 188 se = errno; 189 perror("relay"); 190 errno = se; 191 syslog(LOG_ERR, "relay: %m\n"); 192 exit(-1); 193 } 194 exit(0); 195} 196