busybox/networking/fakeidentd.c

/* NB: this file is to be removed soon. See isrv_identd.c */

/* vi: set sw=4 ts=4: */
/*
 * A fake identd server
 *
 * Adapted to busybox by Thomas Lundquist <thomasez@zelow.no>
 * Original Author: Tomi Ollila <too@iki.fi>
 *                  http://www.guru-group.fi/~too/sw/
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

/* Ident crash course
 *
 * Incoming requests are of form "6191, 23\r\n" - peer asks us
 * "which user connected from your port 6191 to my port 23?"
 * We should answer:
 * "6193, 23 : USERID : UNIX : username\r\n"
 * and close the connection.
 * We can also reply:
 * "6195, 23 : USERID : OTHER[,US-ASCII] : username\r\n"
 * "6195, 23 : ERROR : INVALID-PORT/NO-USER/HIDDEN-USER/UNKNOWN-ERROR\r\n"
 * but we probably will never want that.
 */

#include "busybox.h"

#define SANE_INETD_ONLY_VERSION

#ifdef SANE_INETD_ONLY_VERSION

int fakeidentd_main(int argc, char **argv)
{
	char buf[64];
	const char *bogouser = "nobody";
	char *cur = buf;
	int rem = sizeof(buf)-1;

	if (argv[1])
		bogouser = argv[1];

	alarm(30);
	while (1) {
		char *p;
		int sz = safe_read(0, cur, rem);
		if (sz < 0) return 1;
		cur[sz] = '\0';
		p = strpbrk(cur, "\r\n");
		if (p) {
			*p = '\0';
			break;
		}
		cur += sz;
		rem -= sz;
		if (!rem || !sz)
			break;
	}
	printf("%s : USERID : UNIX : %s\r\n", buf, bogouser);
	return 0;
}

#else

/* Welcome to the bloaty horrors */

#include <sys/syslog.h>
#include <sys/uio.h>

#define MAXCONNS    20
#define MAXIDLETIME 45

static const char ident_substr[] = " : USERID : UNIX : ";
enum { ident_substr_len = sizeof(ident_substr) - 1 };
#define PIDFILE "/var/run/identd.pid"

/*
 * We have to track the 'first connection socket' so that we
 * don't go around closing file descriptors for non-clients.
 *
 * descriptor setup normally
 *  0 = server socket
 *  1 = syslog fd (hopefully -- otherwise this won't work)
 *  2 = connection socket after detached from tty. standard error before that
 *  3 - 2 + MAXCONNS = rest connection sockets
 *
 * To try to make sure that syslog fd is what is "requested", the that fd
 * is closed before openlog() call.  It can only severely fail if fd 0
 * is initially closed.
 */
#define FCS 2

/*
 * FD of the connection is always the index of the connection structure
 * in `conns' array + FCS
 */
static struct {
	time_t lasttime;
	int len;
	char buf[20];
} conns[MAXCONNS];

/* When using global variables, bind those at least to a structure. */
static struct {
	const char *identuser;
	fd_set readfds;
	int conncnt;
} G;

static char *bind_ip_address;

static int chmatch(char c, char *chars)
{
	for (; *chars; chars++)
		if (c == *chars)
			return 1;
	return 0;
}

static int skipchars(char **p, char *chars)
{
	while (chmatch(**p, chars))
		(*p)++;
	if (**p == '\r' || **p == '\n')
		return 0;
	return 1;
}

static int parseAddrs(char *ptr, char **myaddr, char **heraddr)
{
	/* parse <port-on-server> , <port-on-client> */

	if (!skipchars(&ptr, " \t"))
		return -1;

	*myaddr = ptr;

	if (!skipchars(&ptr, "1234567890"))
		return -1;

	if (!chmatch(*ptr, " \t,"))
		return -1;

	*ptr++ = '\0';

	if (!skipchars(&ptr, " \t,") )
		return -1;

	*heraddr = ptr;

	skipchars(&ptr, "1234567890");

	if (!chmatch(*ptr, " \n\r"))
		return -1;

	*ptr = '\0';

	return 0;
}

static void replyError(int s, char *buf)
{
	struct iovec iv[3];
	iv[0].iov_base = "0, 0 : ERROR : ";   iv[0].iov_len = 15;
	iv[1].iov_base = buf;                 iv[1].iov_len = strlen(buf);
	iv[2].iov_base = "\r\n";              iv[2].iov_len = 2;
	writev(s, iv, 3);
}

static void reply(int s, char *buf)
{
	char *myaddr, *heraddr;

	myaddr = heraddr = NULL;

	if (parseAddrs(buf, &myaddr, &heraddr))
		replyError(s, "X-INVALID-REQUEST");
	else {
		struct iovec iv[6];
		iv[0].iov_base = myaddr;               iv[0].iov_len = strlen(myaddr);
		iv[1].iov_base = ", ";                 iv[1].iov_len = 2;
		iv[2].iov_base = heraddr;              iv[2].iov_len = strlen(heraddr);
		iv[3].iov_base = (void *)ident_substr; iv[3].iov_len = ident_substr_len;
		iv[4].iov_base = (void *)G.identuser;  iv[4].iov_len = strlen(G.identuser);
		iv[5].iov_base = "\r\n";               iv[5].iov_len = 2;
		writev(s, iv, 6);
	}
}

static void movefd(int from, int to)
{
	if (from != to) {
		dup2(from, to);
		close(from);
	}
}

static void deleteConn(int s)
{
	int i = s - FCS;

	close(s);

	G.conncnt--;

	/*
	 * Most of the time there is 0 connections. Most often that there
	 * is connections, there is just one connection. When this one connection
	 * closes, i == G.conncnt = 0 -> no copying.
	 * When there is more than one connection, the oldest connections closes
	 * earlier on average. When this happens, the code below starts copying
	 * the connection structure w/ highest index to the place which which is
	 * just deleted. This means that the connection structures are no longer
	 * in chronological order. I'd quess this means that when there is more
	 * than 1 connection, on average every other connection structure needs
	 * to be copied over the time all these connections are deleted.
	 */
	if (i != G.conncnt) {
		memcpy(&conns[i], &conns[G.conncnt], sizeof(conns[0]));
		movefd(G.conncnt + FCS, s);
	}

	FD_CLR(G.conncnt + FCS, &G.readfds);
}

static int closeOldest(void)
{
	time_t min = conns[0].lasttime;
	int idx = 0;
	int i;

	for (i = 1; i < MAXCONNS; i++)
		if (conns[i].lasttime < min)
			idx = i;

	replyError(idx + FCS, "X-SERVER-TOO-BUSY");
	close(idx + FCS);

	return idx;
}

static int checkInput(char *buf, int len, int l)
{
	int i;
	for (i = len; i < len + l; ++i)
		if (buf[i] == '\n')
			return 1;
	return 0;
}

/* May succeed. If not, won't care. */
static const char *to_unlink;
static void writepid(void)
{
	int fd = open(PIDFILE, O_WRONLY|O_CREAT|O_TRUNC, 0664);
	if (fd < 0)
		return;
	to_unlink = PIDFILE;
	fdprintf(fd, "%d\n", getpid());
	close(fd);
}

static void handlexitsigs(int signum)
{
	if (to_unlink)
		if (unlink(to_unlink) < 0)
			close(open(to_unlink, O_WRONLY|O_CREAT|O_TRUNC, 0644));
	exit(0);
}

int fakeidentd_main(int argc, char **argv)
{
	int fd;
	pid_t pid;

	/* FD_ZERO(&G.readfds); - in bss, already zeroed */
	FD_SET(0, &G.readfds);

	/* handle -b <ip> parameter */
	getopt32(argc, argv, "b:", &bind_ip_address);
	/* handle optional REPLY STRING */
	if (optind < argc)
		G.identuser = argv[optind];
	else
		G.identuser = "nobody";

	writepid();
	signal(SIGTERM, handlexitsigs);
	signal(SIGINT,  handlexitsigs);
	signal(SIGQUIT, handlexitsigs);
	signal(SIGHUP, SIG_IGN);
	signal(SIGPIPE, SIG_IGN); /* ignore closed connections when writing */

	fd = create_and_bind_stream_or_die(bind_ip_address, bb_lookup_port("identd", "tcp", 113));
	xlisten(fd, 5);

	pid = fork();
	if (pid < 0)
		bb_perror_msg_and_die("fork");
	if (pid != 0) /* parent */
		exit(0);
	/* child */
	setsid();
	movefd(fd, 0);
	while (fd)
		close(fd--);
	openlog(applet_name, 0, LOG_DAEMON);
	logmode = LOGMODE_SYSLOG;

	/* main loop where we process all events and never exit */
	while (1) {
		fd_set rfds = G.readfds;
		struct timeval tv = { 15, 0 };
		int i;
		int tim = time(NULL);

		select(G.conncnt + FCS, &rfds, NULL, NULL, G.conncnt? &tv: NULL);

		for (i = G.conncnt - 1; i >= 0; i--) {
			int s = i + FCS;

			if (FD_ISSET(s, &rfds)) {
				char *buf = conns[i].buf;
				unsigned len = conns[i].len;
				unsigned l;

				l = read(s, buf + len, sizeof(conns[0].buf) - len);
				if (l > 0) {
					if (checkInput(buf, len, l)) {
						reply(s, buf);
						goto deleteconn;
					} else if (len + l >= sizeof(conns[0].buf)) {
						replyError(s, "X-INVALID-REQUEST");
						goto deleteconn;
					} else {
						conns[i].len += l;
					}
				} else {
					goto deleteconn;
				}
				conns[i].lasttime = tim;
				continue;
deleteconn:
				deleteConn(s);
			} else {
				/* implement as time_after() in linux kernel sources ... */
				if (conns[i].lasttime + MAXIDLETIME <= tim) {
					replyError(s, "X-TIMEOUT");
					deleteConn(s);
				}
			}
		}

		if (FD_ISSET(0, &rfds)) {
			int s = accept(0, NULL, 0);

			if (s < 0) {
				if (errno != EINTR)
					bb_perror_msg("accept");
			} else {
				if (G.conncnt == MAXCONNS)
					i = closeOldest();
				else
					i = G.conncnt++;

				movefd(s, i + FCS); /* move if not already there */
				FD_SET(i + FCS, &G.readfds);
				conns[i].len = 0;
				conns[i].lasttime = time(NULL);
			}
		}
	} /* end of while (1) */

	return 0;
}

#endif /* !SANE_INETD_ONLY_VERSION */
1	niro	532	/* NB: this file is to be removed soon. See isrv_identd.c */
2
3			/* vi: set sw=4 ts=4: */
4			/*
5			* A fake identd server
6			*
7			* Adapted to busybox by Thomas Lundquist <thomasez@zelow.no>
8			* Original Author: Tomi Ollila <too@iki.fi>
9			* http://www.guru-group.fi/~too/sw/
10			*
11			* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
12			*/
13
14			/* Ident crash course
15			*
16			* Incoming requests are of form "6191, 23\r\n" - peer asks us
17			* "which user connected from your port 6191 to my port 23?"
18			* We should answer:
19			* "6193, 23 : USERID : UNIX : username\r\n"
20			* and close the connection.
21			* We can also reply:
22			* "6195, 23 : USERID : OTHER[,US-ASCII] : username\r\n"
23			* "6195, 23 : ERROR : INVALID-PORT/NO-USER/HIDDEN-USER/UNKNOWN-ERROR\r\n"
24			* but we probably will never want that.
25			*/
26
27			#include "busybox.h"
28
29			#define SANE_INETD_ONLY_VERSION
30
31			#ifdef SANE_INETD_ONLY_VERSION
32
33			int fakeidentd_main(int argc, char **argv)
34			{
35			char buf[64];
36			const char *bogouser = "nobody";
37			char *cur = buf;
38			int rem = sizeof(buf)-1;
39
40			if (argv[1])
41			bogouser = argv[1];
42
43			alarm(30);
44			while (1) {
45			char *p;
46			int sz = safe_read(0, cur, rem);
47			if (sz < 0) return 1;
48			cur[sz] = '\0';
49			p = strpbrk(cur, "\r\n");
50			if (p) {
51			*p = '\0';
52			break;
53			}
54			cur += sz;
55			rem -= sz;
56			if (!rem \|\| !sz)
57			break;
58			}
59			printf("%s : USERID : UNIX : %s\r\n", buf, bogouser);
60			return 0;
61			}
62
63			#else
64
65			/* Welcome to the bloaty horrors */
66
67			#include <sys/syslog.h>
68			#include <sys/uio.h>
69
70			#define MAXCONNS 20
71			#define MAXIDLETIME 45
72
73			static const char ident_substr[] = " : USERID : UNIX : ";
74			enum { ident_substr_len = sizeof(ident_substr) - 1 };
75			#define PIDFILE "/var/run/identd.pid"
76
77			/*
78			* We have to track the 'first connection socket' so that we
79			* don't go around closing file descriptors for non-clients.
80			*
81			* descriptor setup normally
82			* 0 = server socket
83			* 1 = syslog fd (hopefully -- otherwise this won't work)
84			* 2 = connection socket after detached from tty. standard error before that
85			* 3 - 2 + MAXCONNS = rest connection sockets
86			*
87			* To try to make sure that syslog fd is what is "requested", the that fd
88			* is closed before openlog() call. It can only severely fail if fd 0
89			* is initially closed.
90			*/
91			#define FCS 2
92
93			/*
94			* FD of the connection is always the index of the connection structure
95			* in `conns' array + FCS
96			*/
97			static struct {
98			time_t lasttime;
99			int len;
100			char buf[20];
101			} conns[MAXCONNS];
102
103			/* When using global variables, bind those at least to a structure. */
104			static struct {
105			const char *identuser;
106			fd_set readfds;
107			int conncnt;
108			} G;
109
110			static char *bind_ip_address;
111
112			static int chmatch(char c, char *chars)
113			{
114			for (; *chars; chars++)
115			if (c == *chars)
116			return 1;
117			return 0;
118			}
119
120			static int skipchars(char *p, char chars)
121			{
122			while (chmatch(**p, chars))
123			(*p)++;
124			if (p == '\r' \|\| p == '\n')
125			return 0;
126			return 1;
127			}
128
129			static int parseAddrs(char ptr, char myaddr, char *heraddr)
130			{
131			/* parse <port-on-server> , <port-on-client> */
132
133			if (!skipchars(&ptr, " \t"))
134			return -1;
135
136			*myaddr = ptr;
137
138			if (!skipchars(&ptr, "1234567890"))
139			return -1;
140
141			if (!chmatch(*ptr, " \t,"))
142			return -1;
143
144			*ptr++ = '\0';
145
146			if (!skipchars(&ptr, " \t,") )
147			return -1;
148
149			*heraddr = ptr;
150
151			skipchars(&ptr, "1234567890");
152
153			if (!chmatch(*ptr, " \n\r"))
154			return -1;
155
156			*ptr = '\0';
157
158			return 0;
159			}
160
161			static void replyError(int s, char *buf)
162			{
163			struct iovec iv[3];
164			iv[0].iov_base = "0, 0 : ERROR : "; iv[0].iov_len = 15;
165			iv[1].iov_base = buf; iv[1].iov_len = strlen(buf);
166			iv[2].iov_base = "\r\n"; iv[2].iov_len = 2;
167			writev(s, iv, 3);
168			}
169
170			static void reply(int s, char *buf)
171			{
172			char myaddr, heraddr;
173
174			myaddr = heraddr = NULL;
175
176			if (parseAddrs(buf, &myaddr, &heraddr))
177			replyError(s, "X-INVALID-REQUEST");
178			else {
179			struct iovec iv[6];
180			iv[0].iov_base = myaddr; iv[0].iov_len = strlen(myaddr);
181			iv[1].iov_base = ", "; iv[1].iov_len = 2;
182			iv[2].iov_base = heraddr; iv[2].iov_len = strlen(heraddr);
183			iv[3].iov_base = (void *)ident_substr; iv[3].iov_len = ident_substr_len;
184			iv[4].iov_base = (void *)G.identuser; iv[4].iov_len = strlen(G.identuser);
185			iv[5].iov_base = "\r\n"; iv[5].iov_len = 2;
186			writev(s, iv, 6);
187			}
188			}
189
190			static void movefd(int from, int to)
191			{
192			if (from != to) {
193			dup2(from, to);
194			close(from);
195			}
196			}
197
198			static void deleteConn(int s)
199			{
200			int i = s - FCS;
201
202			close(s);
203
204			G.conncnt--;
205
206			/*
207			* Most of the time there is 0 connections. Most often that there
208			* is connections, there is just one connection. When this one connection
209			* closes, i == G.conncnt = 0 -> no copying.
210			* When there is more than one connection, the oldest connections closes
211			* earlier on average. When this happens, the code below starts copying
212			* the connection structure w/ highest index to the place which which is
213			* just deleted. This means that the connection structures are no longer
214			* in chronological order. I'd quess this means that when there is more
215			* than 1 connection, on average every other connection structure needs
216			* to be copied over the time all these connections are deleted.
217			*/
218			if (i != G.conncnt) {
219			memcpy(&conns[i], &conns[G.conncnt], sizeof(conns[0]));
220			movefd(G.conncnt + FCS, s);
221			}
222
223			FD_CLR(G.conncnt + FCS, &G.readfds);
224			}
225
226			static int closeOldest(void)
227			{
228			time_t min = conns[0].lasttime;
229			int idx = 0;
230			int i;
231
232			for (i = 1; i < MAXCONNS; i++)
233			if (conns[i].lasttime < min)
234			idx = i;
235
236			replyError(idx + FCS, "X-SERVER-TOO-BUSY");
237			close(idx + FCS);
238
239			return idx;
240			}
241
242			static int checkInput(char *buf, int len, int l)
243			{
244			int i;
245			for (i = len; i < len + l; ++i)
246			if (buf[i] == '\n')
247			return 1;
248			return 0;
249			}
250
251			/* May succeed. If not, won't care. */
252			static const char *to_unlink;
253			static void writepid(void)
254			{
255			int fd = open(PIDFILE, O_WRONLY\|O_CREAT\|O_TRUNC, 0664);
256			if (fd < 0)
257			return;
258			to_unlink = PIDFILE;
259			fdprintf(fd, "%d\n", getpid());
260			close(fd);
261			}
262
263			static void handlexitsigs(int signum)
264			{
265			if (to_unlink)
266			if (unlink(to_unlink) < 0)
267			close(open(to_unlink, O_WRONLY\|O_CREAT\|O_TRUNC, 0644));
268			exit(0);
269			}
270
271			int fakeidentd_main(int argc, char **argv)
272			{
273			int fd;
274			pid_t pid;
275
276			/* FD_ZERO(&G.readfds); - in bss, already zeroed */
277			FD_SET(0, &G.readfds);
278
279			/* handle -b <ip> parameter */
280			getopt32(argc, argv, "b:", &bind_ip_address);
281			/* handle optional REPLY STRING */
282			if (optind < argc)
283			G.identuser = argv[optind];
284			else
285			G.identuser = "nobody";
286
287			writepid();
288			signal(SIGTERM, handlexitsigs);
289			signal(SIGINT, handlexitsigs);
290			signal(SIGQUIT, handlexitsigs);
291			signal(SIGHUP, SIG_IGN);
292			signal(SIGPIPE, SIG_IGN); /* ignore closed connections when writing */
293
294			fd = create_and_bind_stream_or_die(bind_ip_address, bb_lookup_port("identd", "tcp", 113));
295			xlisten(fd, 5);
296
297			pid = fork();
298			if (pid < 0)
299			bb_perror_msg_and_die("fork");
300			if (pid != 0) /* parent */
301			exit(0);
302			/* child */
303			setsid();
304			movefd(fd, 0);
305			while (fd)
306			close(fd--);
307			openlog(applet_name, 0, LOG_DAEMON);
308			logmode = LOGMODE_SYSLOG;
309
310			/* main loop where we process all events and never exit */
311			while (1) {
312			fd_set rfds = G.readfds;
313			struct timeval tv = { 15, 0 };
314			int i;
315			int tim = time(NULL);
316
317			select(G.conncnt + FCS, &rfds, NULL, NULL, G.conncnt? &tv: NULL);
318
319			for (i = G.conncnt - 1; i >= 0; i--) {
320			int s = i + FCS;
321
322			if (FD_ISSET(s, &rfds)) {
323			char *buf = conns[i].buf;
324			unsigned len = conns[i].len;
325			unsigned l;
326
327			l = read(s, buf + len, sizeof(conns[0].buf) - len);
328			if (l > 0) {
329			if (checkInput(buf, len, l)) {
330			reply(s, buf);
331			goto deleteconn;
332			} else if (len + l >= sizeof(conns[0].buf)) {
333			replyError(s, "X-INVALID-REQUEST");
334			goto deleteconn;
335			} else {
336			conns[i].len += l;
337			}
338			} else {
339			goto deleteconn;
340			}
341			conns[i].lasttime = tim;
342			continue;
343			deleteconn:
344			deleteConn(s);
345			} else {
346			/* implement as time_after() in linux kernel sources ... */
347			if (conns[i].lasttime + MAXIDLETIME <= tim) {
348			replyError(s, "X-TIMEOUT");
349			deleteConn(s);
350			}
351			}
352			}
353
354			if (FD_ISSET(0, &rfds)) {
355			int s = accept(0, NULL, 0);
356
357			if (s < 0) {
358			if (errno != EINTR)
359			bb_perror_msg("accept");
360			} else {
361			if (G.conncnt == MAXCONNS)
362			i = closeOldest();
363			else
364			i = G.conncnt++;
365
366			movefd(s, i + FCS); /* move if not already there */
367			FD_SET(i + FCS, &G.readfds);
368			conns[i].len = 0;
369			conns[i].lasttime = time(NULL);
370			}
371			}
372			} /* end of while (1) */
373
374			return 0;
375			}
376
377			#endif /* !SANE_INETD_ONLY_VERSION */