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
27 char ibuff[RELAY_BUFSZ];
28 char obuff[RELAY_BUFSZ];
29
relay(ifd,ofd,rfd)30 int 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
main(argc,argv)104 main(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