Diff of /trunk/mkinitrd-magellan/busybox/networking/dnsd.c

Parent Directory | Revision Log | Patch

	revision 532 by niro, Sat Sep 1 22:45:15 2007 UTC	revision 816 by niro, Fri Apr 24 18:33:46 2009 UTC
#	Line 17	Line 17
17	* the first porting of oao' scdns to busybox also.	* the first porting of oao' scdns to busybox also.
18	*/	*/
19
20	#include "busybox.h"	#include "libbb.h"
21		#include <syslog.h>
	static const char *fileconf = "/etc/dnsd.conf";
	#define LOCK_FILE       "/var/run/dnsd.lock"
	// Must match getopt32 call
	#define OPT_daemon  (option_mask32 & 0x10)
	#define OPT_verbose (option_mask32 & 0x20)
22
23	//#define DEBUG 1	//#define DEBUG 1
24	#define DEBUG 0	#define DEBUG 0
#	Line 42  enum {	Line 36  enum {
36	ttl(4B) + rlen(2B) + r (MAX_NAME_LEN =21B) +	ttl(4B) + rlen(2B) + r (MAX_NAME_LEN =21B) +
37	2*querystring (2 MAX_NAME_LEN= 42B), all together 90 Byte	2*querystring (2 MAX_NAME_LEN= 42B), all together 90 Byte
38	*/	*/
39	MAX_PACK_LEN = 512 + 1,	MAX_PACK_LEN = 512,
40
41	DEFAULT_TTL = 30,       // increase this when not testing?	DEFAULT_TTL = 30,       // increase this when not testing?
42
#	Line 50  enum {	Line 44  enum {
44	REQ_PTR = 12	REQ_PTR = 12
45	};	};
46
	struct dns_repl { // resource record, add 0 or 1 to accepted dns_msg in resp
	uint16_t rlen;
	uint8_t *r; // resource
	uint16_t flags;
	};
47	struct dns_head { // the message from client and first part of response mag	struct dns_head { // the message from client and first part of response mag
48	uint16_t id;	uint16_t id;
49	uint16_t flags;	uint16_t flags;
#	Line 75  struct dns_entry { // element of known	Line 63  struct dns_entry { // element of known
63	char name[MAX_HOST_LEN];	char name[MAX_HOST_LEN];
64	};	};
65
66	static struct dns_entry *dnsentry = NULL;	static struct dns_entry *dnsentry;
67	static uint32_t ttl = DEFAULT_TTL;	static uint32_t ttl = DEFAULT_TTL;
68
69		static const char *fileconf = "/etc/dnsd.conf";
70
71		// Must match getopt32 call
72		#define OPT_daemon  (option_mask32 & 0x10)
73		#define OPT_verbose (option_mask32 & 0x20)
74
75
76	/*	/*
77	* Convert host name from C-string to dns length/string.	* Convert host name from C-string to dns length/string.
78	*/	*/
#	Line 107  static void undot(uint8_t * rip)	Line 102  static void undot(uint8_t * rip)
102	}	}
103
104	/*	/*
	* Read one line of hostname/IP from file
	* Returns 0 for each valid entry read, -1 at EOF
	* Assumes all host names are lower case only
	* Hostnames with more than one label is not handled correctly.
	* Presently the dot is copied into name without
	* converting to a length/string substring for that label.
	*/
	static int getfileentry(FILE * fp, struct dns_entry *s)
	{
	unsigned int a,b,c,d;
	char *r, *name;
	restart:
	r = xmalloc_fgets(fp);
	if (!r)
	return -1;
	while (*r == ' ' || *r == '\t') {
	r++;
	if (!*r || *r == '#' || *r == '\n')
	goto restart; /* skipping empty/blank and commented lines  */
	}
	name = r;
	while (*r != ' ' && *r != '\t')
	r++;
	*r++ = 0;
	if (sscanf(r, "%u.%u.%u.%u", &a, &b, &c, &d) != 4)
	goto restart; /* skipping wrong lines */
	sprintf(s->ip, "%u.%u.%u.%u", a, b, c, d);
	sprintf(s->rip, ".%u.%u.%u.%u", d, c, b, a);
	undot((uint8_t*)s->rip);
	convname(s->name,(uint8_t*)name);
	if (OPT_verbose)
	fprintf(stderr, "\tname:%s, ip:%s\n", &(s->name[1]),s->ip);
	return 0;
	}
	/*
105	* Read hostname/IP records from file	* Read hostname/IP records from file
106	*/	*/
107	static void dnsentryinit(void)	static void dnsentryinit(void)
108	{	{
109	FILE *fp;	char *token[2];
110		parser_t *parser;
111	struct dns_entry *m, *prev;	struct dns_entry *m, *prev;
	prev = dnsentry = NULL;
	fp = xfopen(fileconf, "r");
112
113	while (1) {	prev = dnsentry = NULL;
114	m = xmalloc(sizeof(struct dns_entry));	parser = config_open(fileconf);
115		while (config_read(parser, token, 2, 2, "# \t", PARSE_NORMAL)) {
116		unsigned a, b, c, d;
117		/*
118		* Assumes all host names are lower case only
119		* Hostnames with more than one label are not handled correctly.
120		* Presently the dot is copied into name without
121		* converting to a length/string substring for that label.
122		*/
123		// if (!token[1] || sscanf(token[1], ".%u.%u.%u.%u"+1, &a, &b, &c, &d) != 4)
124		if (sscanf(token[1], ".%u.%u.%u.%u"+1, &a, &b, &c, &d) != 4)
125		continue;
126
127		m = xzalloc(sizeof(*m));
128		/*m->next = NULL;*/
129		sprintf(m->ip, ".%u.%u.%u.%u"+1, a, b, c, d);
130		sprintf(m->rip, ".%u.%u.%u.%u", d, c, b, a);
131		undot((uint8_t*)m->rip);
132		convname(m->name, (uint8_t*)token[0]);
133
134	m->next = NULL;	if (OPT_verbose)
135	if (getfileentry(fp, m))	fprintf(stderr, "\tname:%s, ip:%s\n", &(m->name[1]), m->ip);
	break;
136
137	if (prev == NULL)	if (prev == NULL)
138	dnsentry = m;	dnsentry = m;
#	Line 171  static void dnsentryinit(void)	Line 140  static void dnsentryinit(void)
140	prev->next = m;	prev->next = m;
141	prev = m;	prev = m;
142	}	}
143	fclose(fp);	config_close(parser);
144	}	}
145
146	/*	/*
#	Line 181  static void dnsentryinit(void)	Line 150  static void dnsentryinit(void)
150	static int table_lookup(uint16_t type, uint8_t * as, uint8_t * qs)	static int table_lookup(uint16_t type, uint8_t * as, uint8_t * qs)
151	{	{
152	int i;	int i;
153	struct dns_entry *d=dnsentry;	struct dns_entry *d = dnsentry;
154
155	do {	do {
156	#if DEBUG	#if DEBUG
#	Line 196  static int table_lookup(uint16_t type, u	Line 165  static int table_lookup(uint16_t type, u
165	for (i = 1; i <= (int)(d->name[0]); i++)	for (i = 1; i <= (int)(d->name[0]); i++)
166	if (tolower(qs[i]) != d->name[i])	if (tolower(qs[i]) != d->name[i])
167	break;	break;
168	if (i > (int)(d->name[0])) {	if (i > (int)(d->name[0]) ||
169	#if DEBUG	(d->name[0] == 1 && d->name[1] == '*')) {
	fprintf(stderr, " OK");
	#endif
170	strcpy((char *)as, d->ip);	strcpy((char *)as, d->ip);
171	#if DEBUG	#if DEBUG
172	fprintf(stderr, " as:%s\n", as);	fprintf(stderr, " OK as:%s\n", as);
173	#endif	#endif
174	return 0;	return 0;
175	}	}
176	} else	} else if (type == REQ_PTR) { /* search by IP-address */
177	if (type == REQ_PTR) { /* search by IP-address */	if ((d->name[0] != 1 || d->name[1] != '*') &&
178	if (!strncmp((char*)&d->rip[1], (char*)&qs[1], strlen(d->rip)-1)) {	!strncmp((char*)&d->rip[1], (char*)&qs[1], strlen(d->rip)-1)) {
179	strcpy((char *)as, d->name);	strcpy((char *)as, d->name);
180	return 0;	return 0;
181	}	}
#	Line 218  static int table_lookup(uint16_t type, u	Line 185  static int table_lookup(uint16_t type, u
185	return -1;	return -1;
186	}	}
187
188	/*	/*
189	* Decode message and generate answer	* Decode message and generate answer
190	*/	*/
191	#define eret(s) do { fputs(s, stderr); return -1; } while (0)	static int process_packet(uint8_t *buf)
	static int process_packet(uint8_t * buf)
192	{	{
193		uint8_t answstr[MAX_NAME_LEN + 1];
194	struct dns_head *head;	struct dns_head *head;
195	struct dns_prop *qprop;	struct dns_prop *qprop;
196	struct dns_repl outr;	uint8_t *from, *answb;
197	void *next, *from, *answb;	uint16_t outr_rlen;
198		uint16_t outr_flags;
	uint8_t answstr[MAX_NAME_LEN + 1];
	int lookup_result, type, len, packet_len;
199	uint16_t flags;	uint16_t flags;
200		int lookup_result, type, packet_len;
201		int querystr_len;
202
203	answstr[0] = '\0';	answstr[0] = '\0';
204
205	head = (struct dns_head *)buf;	head = (struct dns_head *)buf;
206	if (head->nquer == 0)	if (head->nquer == 0) {
207	eret("no queries\n");	bb_error_msg("no queries");
208		return -1;
209		}
210
211	if (head->flags & 0x8000)	if (head->flags & 0x8000) {
212	eret("ignoring response packet\n");	bb_error_msg("ignoring response packet");
213		return -1;
214		}
215
216	from = (void *)&head[1]; //  start of query string	from = (void *)&head[1]; //  start of query string
217	next = answb = from + strlen((char *)from) + 1 + sizeof(struct dns_prop);   // where to append answer block	//FIXME: strlen of untrusted data??!
218		querystr_len = strlen((char *)from) + 1 + sizeof(struct dns_prop);
219		answb = from + querystr_len;   // where to append answer block
220
221	outr.rlen = 0; // may change later	outr_rlen = 0;
222	outr.r = NULL;	outr_flags = 0;
	outr.flags = 0;
223
224	qprop = (struct dns_prop *)(answb - 4);	qprop = (struct dns_prop *)(answb - 4);
225	type = ntohs(qprop->type);	type = ntohs(qprop->type);
#	Line 259  static int process_packet(uint8_t * buf)	Line 230  static int process_packet(uint8_t * buf)
230	}	}
231
232	if (ntohs(qprop->class) != 1 /* class INET */ ) {	if (ntohs(qprop->class) != 1 /* class INET */ ) {
233	outr.flags = 4; /* not supported */	outr_flags = 4; /* not supported */
234	goto empty_packet;	goto empty_packet;
235	}	}
236	/* we only support standard queries */	/* we only support standard queries */
#	Line 269  static int process_packet(uint8_t * buf)	Line 240  static int process_packet(uint8_t * buf)
240
241	// We have a standard query	// We have a standard query
242	bb_info_msg("%s", (char *)from);	bb_info_msg("%s", (char *)from);
243	lookup_result = table_lookup(type, answstr, (uint8_t*)from);	lookup_result = table_lookup(type, answstr, from);
244	if (lookup_result != 0) {	if (lookup_result != 0) {
245	outr.flags = 3 | 0x0400; //name do not exist and auth	outr_flags = 3 | 0x0400; // name do not exist and auth
246	goto empty_packet;	goto empty_packet;
247	}	}
248	if (type == REQ_A) {    // return an address	if (type == REQ_A) {    // return an address
249	struct in_addr a;	struct in_addr a; // NB! its "struct { unsigned __long__ s_addr; }"
250	if (!inet_aton((char*)answstr, &a)) {//dotted dec to long conv	uint32_t v32;
251	outr.flags = 1; /* Frmt err */	if (!inet_aton((char*)answstr, &a)) { //dotted dec to long conv
252		outr_flags = 1; /* Frmt err */
253	goto empty_packet;	goto empty_packet;
254	}	}
255	memcpy(answstr, &a.s_addr, 4); // save before a disappears	v32 = a.s_addr; /* in case long != int */
256	outr.rlen = 4; // uint32_t IP	memcpy(answstr, &v32, 4);
257	}	outr_rlen = 4; // uint32_t IP
258	else	} else
259	outr.rlen = strlen((char *)answstr) + 1; // a host name	outr_rlen = strlen((char *)answstr) + 1; // a host name
260	outr.r = answstr; // 32 bit ip or a host name	outr_flags |= 0x0400; /* authority-bit */
	outr.flags |= 0x0400; /* authority-bit */
261	// we have an answer	// we have an answer
262	head->nansw = htons(1);	head->nansw = htons(1);
263
264	// copy query block to answer block	// copy query block to answer block
265	len = answb - from;	memcpy(answb, from, querystr_len);
266	memcpy(answb, from, len);	answb += querystr_len;
	next += len;
267
268	// and append answer rr	// and append answer rr
269	*(uint32_t *) next = htonl(ttl);	// FIXME: unaligned accesses??
270	next += 4;	*(uint32_t *) answb = htonl(ttl);
271	*(uint16_t *) next = htons(outr.rlen);	answb += 4;
272	next += 2;	*(uint16_t *) answb = htons(outr_rlen);
273	memcpy(next, (void *)answstr, outr.rlen);	answb += 2;
274	next += outr.rlen;	memcpy(answb, answstr, outr_rlen);
275		answb += outr_rlen;
276
277	empty_packet:	empty_packet:
278
279	flags = ntohs(head->flags);	flags = ntohs(head->flags);
280	// clear rcode and RA, set responsebit and our new flags	// clear rcode and RA, set responsebit and our new flags
281	flags |= (outr.flags & 0xff80) | 0x8000;	flags |= (outr_flags & 0xff80) | 0x8000;
282	head->flags = htons(flags);	head->flags = htons(flags);
283	head->nauth = head->nadd = htons(0);	head->nauth = head->nadd = 0;
284	head->nquer = htons(1);	head->nquer = htons(1);
285
286	packet_len = next - (void *)buf;	packet_len = answb - buf;
287	return packet_len;	return packet_len;
288	}	}
289
290	/*	/*
291	* Exit on signal	* Exit on signal
292	*/	*/
293	static void interrupt(int x)	static void interrupt(int sig)
294	{	{
295	unlink(LOCK_FILE);	/* unlink("/var/run/dnsd.lock"); */
296	bb_error_msg("interrupt, exiting\n");	bb_error_msg("interrupt, exiting\n");
297	exit(2);	kill_myself_with_sig(sig);
298	}	}
299
300	int dnsd_main(int argc, char **argv)	int dnsd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
301		int dnsd_main(int argc UNUSED_PARAM, char **argv)
302	{	{
303	char *listen_interface = NULL;	const char *listen_interface = "0.0.0.0";
304	char *sttl, *sport;	char *sttl, *sport;
305	len_and_sockaddr *lsa;	len_and_sockaddr *lsa, *from, *to;
306		unsigned lsa_size;
307	int udps;	int udps;
308	uint16_t port = 53;	uint16_t port = 53;
309	uint8_t buf[MAX_PACK_LEN];	/* Paranoid sizing: querystring x2 + ttl + outr_rlen + answstr */
310		/* I'd rather see process_packet() fixed instead... */
311		uint8_t buf[MAX_PACK_LEN * 2 + 4 + 2 + (MAX_NAME_LEN+1)];
312
313	getopt32(argc, argv, "i:c:t:p:dv", &listen_interface, &fileconf, &sttl, &sport);	getopt32(argv, "i:c:t:p:dv", &listen_interface, &fileconf, &sttl, &sport);
314	//if (option_mask32 & 0x1) // -i	//if (option_mask32 & 0x1) // -i
315	//if (option_mask32 & 0x2) // -c	//if (option_mask32 & 0x2) // -c
316	if (option_mask32 & 0x4) // -t	if (option_mask32 & 0x4) // -t
317	ttl = xatou_range(sttl, 1, 0xffffffff);	ttl = xatou_range(sttl, 1, 0xffffffff);
318	if (option_mask32 & 0x8) // -p	if (option_mask32 & 0x8) // -p
319	port = xatou_range(sttl, 1, 0xffff);	port = xatou_range(sport, 1, 0xffff);
320
321	if (OPT_verbose) {	if (OPT_verbose) {
322	bb_info_msg("listen_interface: %s", listen_interface);	bb_info_msg("listen_interface: %s", listen_interface);
#	Line 350  int dnsd_main(int argc, char **argv)	Line 325  int dnsd_main(int argc, char **argv)
325	}	}
326
327	if (OPT_daemon) {	if (OPT_daemon) {
328	//FIXME: NOMMU will NOT set LOGMODE_SYSLOG!	bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, argv);
329	#ifdef BB_NOMMU	openlog(applet_name, LOG_PID, LOG_DAEMON);
	/* reexec for vfork() do continue parent */
	vfork_daemon_rexec(1, 0, argc, argv, "-d");
	#else
	xdaemon(1, 0);
	#endif
330	logmode = LOGMODE_SYSLOG;	logmode = LOGMODE_SYSLOG;
331	}	}
332
333	dnsentryinit();	dnsentryinit();
334
335	signal(SIGINT, interrupt);	signal(SIGINT, interrupt);
336	signal(SIGPIPE, SIG_IGN);	bb_signals(0
337	signal(SIGHUP, SIG_IGN);	/* why? + (1 << SIGPIPE) */
338		+ (1 << SIGHUP)
339	#ifdef SIGTSTP	#ifdef SIGTSTP
340	signal(SIGTSTP, SIG_IGN);	+ (1 << SIGTSTP)
341	#endif	#endif
342	#ifdef SIGURG	#ifdef SIGURG
343	signal(SIGURG, SIG_IGN);	+ (1 << SIGURG)
344	#endif	#endif
345		, SIG_IGN);
346
347		lsa = xdotted2sockaddr(listen_interface, port);
348		udps = xsocket(lsa->u.sa.sa_family, SOCK_DGRAM, 0);
349		xbind(udps, &lsa->u.sa, lsa->len);
350		socket_want_pktinfo(udps); /* needed for recv_from_to to work */
351		lsa_size = LSA_LEN_SIZE + lsa->len;
352		from = xzalloc(lsa_size);
353		to = xzalloc(lsa_size);
354
	lsa = host2sockaddr(listen_interface, port);
	udps = xsocket(lsa->sa.sa_family, SOCK_DGRAM, 0);
	xbind(udps, &lsa->sa, lsa->len);
	// xlisten(udps, 50); - ?!! DGRAM sockets are never listened on I think?
355	bb_info_msg("Accepting UDP packets on %s",	bb_info_msg("Accepting UDP packets on %s",
356	xmalloc_sockaddr2dotted(&lsa->sa, lsa->len));	xmalloc_sockaddr2dotted(&lsa->u.sa));
357
358	while (1) {	while (1) {
	fd_set fdset;
359	int r;	int r;
360		/* Try to get *DEST* address (to which of our addresses
361	FD_ZERO(&fdset);	* this query was directed), and reply from the same address.
362	FD_SET(udps, &fdset);	* Or else we can exhibit usual UDP ugliness:
363	// Block until a message arrives	* [ip1.multihomed.ip2] <=  query to ip1  <= peer
364	// FIXME: Fantastic. select'ing on just one fd??	* [ip1.multihomed.ip2] => reply from ip2 => peer (confused) */
365	// Why no just block on it doing recvfrom() ?	memcpy(to, lsa, lsa_size);
366	r = select(udps + 1, &fdset, NULL, NULL, NULL);	r = recv_from_to(udps, buf, MAX_PACK_LEN + 1, 0, &from->u.sa, &to->u.sa, lsa->len);
367	if (r < 0)	if (r < 12 || r > MAX_PACK_LEN) {
368	bb_perror_msg_and_die("select error");	bb_error_msg("invalid packet size");
369	if (r == 0)	continue;
	bb_perror_msg_and_die("select spurious return");
	/* Can this test ever be false? - yes */
	if (FD_ISSET(udps, &fdset)) {
	socklen_t fromlen = lsa->len;
	// FIXME: need to get *DEST* address (to which of our addresses
	// this query was directed), and reply from the same address.
	// Or else we can exhibit usual UDP ugliness:
	// [ip1.multihomed.ip2] <=  query to ip1  <= peer
	// [ip1.multihomed.ip2] => reply from ip2 => peer (confused)
	r = recvfrom(udps, buf, sizeof(buf), 0, &lsa->sa, &fromlen);
	if (OPT_verbose)
	bb_info_msg("Got UDP packet");
	if (r < 12 || r > 512) {
	bb_error_msg("invalid packet size");
	continue;
	}
	if (r <= 0)
	continue;
	r = process_packet(buf);
	if (r <= 0)
	continue;
	sendto(udps, buf, r, 0, &lsa->sa, fromlen);
370	}	}
371		if (OPT_verbose)
372		bb_info_msg("Got UDP packet");
373		buf[r] = '\0'; /* paranoia */
374		r = process_packet(buf);
375		if (r <= 0)
376		continue;
377		send_to_from(udps, buf, r, 0, &from->u.sa, &to->u.sa, lsa->len);
378	}	}
379		return 0;
380	}	}

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Legend: Removed from v.532   changed lines   Added in v.816