proxy.c revision 145511 
1146822Sharti/*	$NetBSD$	*/
2
3/*
4 * Sample transparent proxy program.
5 *
6 * Sample implementation of a program which intercepts a TCP connectiona and
7 * just echos all data back to the origin.  Written to work via inetd as a
8 * "nonwait" program running as root; ie.
9 * tcpmux          stream  tcp     nowait root /usr/local/bin/proxy proxy
10 * with a NAT rue like this:
11 * rdr smc0 0/0 port 80 -> 127.0.0.1/32 port 1
12 */
13#include <stdio.h>
14#include <string.h>
15#include <fcntl.h>
16#include <syslog.h>
17#if !defined(__SVR4) && !defined(__svr4__)
18#include <strings.h>
19#else
20#include <sys/byteorder.h>
21#endif
22#include <sys/types.h>
23#include <sys/time.h>
24#include <sys/param.h>
25#include <stdlib.h>
26#include <unistd.h>
27#include <stddef.h>
28#include <sys/socket.h>
29#include <sys/ioctl.h>
30#if defined(sun) && (defined(__svr4__) || defined(__SVR4))
31# include <sys/ioccom.h>
32# include <sys/sysmacros.h>
33#endif
34#include <netinet/in.h>
35#include <netinet/in_systm.h>
36#include <netinet/ip.h>
37#include <netinet/tcp.h>
38#include <net/if.h>
39#include <netdb.h>
40#include <arpa/nameser.h>
41#include <arpa/inet.h>
42#include <resolv.h>
43#include <ctype.h>
44#include "netinet/ip_compat.h"
45#include "netinet/ip_fil.h"
46#include "netinet/ip_nat.h"
47#include "netinet/ip_state.h"
48#include "netinet/ip_proxy.h"
49#include "netinet/ip_nat.h"
50#include "netinet/ipl.h"
51
52
53main(argc, argv)
54int argc;
55char *argv[];
56{
57	struct	sockaddr_in	sin, sloc, sout;
58	ipfobj_t	obj;
59	natlookup_t	natlook;
60	natlookup_t	*natlookp = &natlook;
61	char	buffer[512];
62	int	namelen, fd, n;
63
64	/*
65	 * get IP# and port # of the remote end of the connection (at the
66	 * origin).
67	 */
68	namelen = sizeof(sin);
69	if (getpeername(0, (struct sockaddr *)&sin, &namelen) == -1) {
70		perror("getpeername");
71		exit(-1);
72	}
73
74	/*
75	 * get IP# and port # of the local end of the connection (at the
76	 * man-in-the-middle).
77	 */
78	namelen = sizeof(sin);
79	if (getsockname(0, (struct sockaddr *)&sloc, &namelen) == -1) {
80		perror("getsockname");
81		exit(-1);
82	}
83
84	bzero((char *)&obj, sizeof(obj));
85	obj.ipfo_rev = IPFILTER_VERSION;
86	obj.ipfo_size = sizeof(natlook);
87	obj.ipfo_ptr = &natlook;
88	obj.ipfo_type = IPFOBJ_NATLOOKUP;
89
90	/*
91	 * Build up the NAT natlookup structure.
92	 */
93	bzero((char *)&natlook, sizeof(natlook));
94	natlook.nl_outip = sin.sin_addr;
95	natlook.nl_inip = sloc.sin_addr;
96	natlook.nl_flags = IPN_TCP;
97	natlook.nl_outport = ntohs(sin.sin_port);
98	natlook.nl_inport = ntohs(sloc.sin_port);
99
100	/*
101	 * Open the NAT device and lookup the mapping pair.
102	 */
103	fd = open(IPNAT_NAME, O_RDONLY);
104	if (ioctl(fd, SIOCGNATL, &obj) == -1) {
105		perror("ioctl(SIOCGNATL)");
106		exit(-1);
107	}
108
109#define	DO_NAT_OUT
110#ifdef	DO_NAT_OUT
111	if (argc > 1)
112		do_nat_out(0, 1, fd, &natlook, argv[1]);
113#else
114
115	/*
116	 * Log it
117	 */
118	syslog(LOG_DAEMON|LOG_INFO, "connect to %s,%d",
119		inet_ntoa(natlook.nl_realip), ntohs(natlook.nl_realport));
120	printf("connect to %s,%d\n",
121		inet_ntoa(natlook.nl_realip), ntohs(natlook.nl_realport));
122
123	/*
124	 * Just echo data read in from stdin to stdout
125	 */
126	while ((n = read(0, buffer, sizeof(buffer))) > 0)
127		if (write(1, buffer, n) != n)
128			break;
129	close(0);
130#endif
131}
132
133
134#ifdef	DO_NAT_OUT
135do_nat_out(in, out, fd, nlp, extif)
136int fd;
137natlookup_t *nlp;
138char *extif;
139{
140	nat_save_t ns, *nsp = &ns;
141	struct sockaddr_in usin;
142	u_32_t sum1, sum2, sumd;
143	int onoff, ofd, slen;
144	ipfobj_t obj;
145	ipnat_t *ipn;
146	nat_t *nat;
147
148	bzero((char *)&ns, sizeof(ns));
149
150	nat = &ns.ipn_nat;
151	nat->nat_p = IPPROTO_TCP;
152	nat->nat_dir = NAT_OUTBOUND;
153	if ((extif != NULL) && (*extif != '\0')) {
154		strncpy(nat->nat_ifnames[0], extif,
155			sizeof(nat->nat_ifnames[0]));
156		strncpy(nat->nat_ifnames[1], extif,
157			sizeof(nat->nat_ifnames[1]));
158		nat->nat_ifnames[0][sizeof(nat->nat_ifnames[0]) - 1] = '\0';
159		nat->nat_ifnames[1][sizeof(nat->nat_ifnames[1]) - 1] = '\0';
160	}
161
162	ofd = socket(AF_INET, SOCK_DGRAM, 0);
163	bzero((char *)&usin, sizeof(usin));
164	usin.sin_family = AF_INET;
165	usin.sin_addr = nlp->nl_realip;
166	usin.sin_port = nlp->nl_realport;
167	(void) connect(ofd, (struct sockaddr *)&usin, sizeof(usin));
168	slen = sizeof(usin);
169	(void) getsockname(ofd, (struct sockaddr *)&usin, &slen);
170	close(ofd);
171printf("local IP# to use: %s\n", inet_ntoa(usin.sin_addr));
172
173	if ((ofd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
174		perror("socket");
175	usin.sin_port = 0;
176	if (bind(ofd, (struct sockaddr *)&usin, sizeof(usin)))
177		perror("bind");
178	slen = sizeof(usin);
179	if (getsockname(ofd, (struct sockaddr *)&usin, &slen))
180		perror("getsockname");
181printf("local port# to use: %d\n", ntohs(usin.sin_port));
182
183	nat->nat_inip = usin.sin_addr;
184	nat->nat_outip = nlp->nl_outip;
185	nat->nat_oip = nlp->nl_realip;
186
187	sum1 = LONG_SUM(ntohl(usin.sin_addr.s_addr)) + ntohs(usin.sin_port);
188	sum2 = LONG_SUM(ntohl(nat->nat_outip.s_addr)) + ntohs(nlp->nl_outport);
189	CALC_SUMD(sum1, sum2, sumd);
190	nat->nat_sumd[0] = (sumd & 0xffff) + (sumd >> 16);
191	nat->nat_sumd[1] = nat->nat_sumd[0];
192
193	sum1 = LONG_SUM(ntohl(usin.sin_addr.s_addr));
194	sum2 = LONG_SUM(ntohl(nat->nat_outip.s_addr));
195	CALC_SUMD(sum1, sum2, sumd);
196	nat->nat_ipsumd = (sumd & 0xffff) + (sumd >> 16);
197
198	nat->nat_inport = usin.sin_port;
199	nat->nat_outport = nlp->nl_outport;
200	nat->nat_oport = nlp->nl_realport;
201
202	nat->nat_flags = IPN_TCPUDP;
203
204	bzero((char *)&obj, sizeof(obj));
205	obj.ipfo_rev = IPFILTER_VERSION;
206	obj.ipfo_size = sizeof(*nsp);
207	obj.ipfo_ptr = nsp;
208	obj.ipfo_type = IPFOBJ_NATSAVE;
209
210	onoff = 1;
211	if (ioctl(fd, SIOCSTLCK, &onoff) == 0) {
212		if (ioctl(fd, SIOCSTPUT, &obj) != 0)
213			perror("SIOCSTPUT");
214		onoff = 0;
215		if (ioctl(fd, SIOCSTLCK, &onoff) != 0)
216			perror("SIOCSTLCK");
217	}
218
219	usin.sin_addr = nlp->nl_realip;
220	usin.sin_port = nlp->nl_realport;
221printf("remote end for connection: %s,%d\n", inet_ntoa(usin.sin_addr),
222ntohs(usin.sin_port));
223fflush(stdout);
224	if (connect(ofd, (struct sockaddr *)&usin, sizeof(usin)))
225		perror("connect");
226
227	relay(in, out, ofd);
228}
229
230
231relay(in, out, net)
232int in, out, net;
233{
234	char netbuf[1024], outbuf[1024];
235	char *nwptr, *nrptr, *owptr, *orptr;
236	size_t nsz, osz;
237	fd_set rd, wr;
238	int i, n, maxfd;
239
240	n = 0;
241	maxfd = in;
242	if (out > maxfd)
243		maxfd = out;
244	if (net > maxfd)
245		maxfd = net;
246
247	nrptr = netbuf;
248	nwptr = netbuf;
249	nsz = sizeof(netbuf);
250	orptr = outbuf;
251	owptr = outbuf;
252	osz = sizeof(outbuf);
253
254	while (n >= 0) {
255		FD_ZERO(&rd);
256		FD_ZERO(&wr);
257
258		if (nrptr - netbuf < sizeof(netbuf))
259			FD_SET(in, &rd);
260		if (orptr - outbuf < sizeof(outbuf))
261			FD_SET(net, &rd);
262
263		if (nsz < sizeof(netbuf))
264			FD_SET(net, &wr);
265		if (osz < sizeof(outbuf))
266			FD_SET(out, &wr);
267
268		n = select(maxfd + 1, &rd, &wr, NULL, NULL);
269
270		if ((n > 0) && FD_ISSET(in, &rd)) {
271			i = read(in, nrptr, sizeof(netbuf) - (nrptr - netbuf));
272			if (i <= 0)
273				break;
274			nsz -= i;
275			nrptr += i;
276			n--;
277		}
278
279		if ((n > 0) && FD_ISSET(net, &rd)) {
280			i = read(net, orptr, sizeof(outbuf) - (orptr - outbuf));
281			if (i <= 0)
282				break;
283			osz -= i;
284			orptr += i;
285			n--;
286		}
287
288		if ((n > 0) && FD_ISSET(out, &wr)) {
289			i = write(out, owptr, orptr - owptr);
290			if (i <= 0)
291				break;
292			osz += i;
293			if (osz == sizeof(outbuf) || owptr == orptr) {
294				orptr = outbuf;
295				owptr = outbuf;
296			} else
297				owptr += i;
298			n--;
299		}
300
301		if ((n > 0) && FD_ISSET(net, &wr)) {
302			i = write(net, nwptr, nrptr - nwptr);
303			if (i <= 0)
304				break;
305			nsz += i;
306			if (nsz == sizeof(netbuf) || nwptr == nrptr) {
307				nrptr = netbuf;
308				nwptr = netbuf;
309			} else
310				nwptr += i;
311		}
312	}
313
314	close(net);
315	close(out);
316	close(in);
317}
318#endif
319