1 #include <u.h>
2 #include <libc.h>
3 #include <ip.h>
4 #include "dns.h"
5 
6 enum
7 {
8 	Maxpath=		128,
9 };
10 
11 char	*logfile = "dns";
12 char	*dbfile;
13 int	debug;
14 int	cachedb = 1;
15 int	testing;
16 int traceactivity;
17 int	needrefresh;
18 int 	resolver;
19 char	mntpt[Maxpath];
20 char	*caller = "";
21 ulong	now;
22 int	maxage;
23 uchar	ipaddr[IPaddrlen];	/* my ip address */
24 char	*LOG;
25 char	*zonerefreshprogram;
26 
27 static int	readmsg(int, uchar*, int);
28 static void	reply(int, DNSmsg*, Request*);
29 static void	dnzone(DNSmsg*, DNSmsg*, Request*);
30 static void	getcaller(char*);
31 static void	refreshmain(char*);
32 
33 void
34 main(int argc, char *argv[])
35 {
36 	int len;
37 	Request req;
38 	DNSmsg reqmsg, repmsg;
39 	uchar buf[512];
40 	char tname[32];
41 	char *err;
42 	char *ext = "";
43 
44 	ARGBEGIN{
45 	case 'd':
46 		debug++;
47 		break;
48 	case 'f':
49 		dbfile = ARGF();
50 		break;
51 	case 'r':
52 		resolver = 1;
53 		break;
54 	case 'x':
55 		ext = ARGF();
56 		break;
57 	}ARGEND
58 
59 	if(debug < 2)
60 		debug = 0;
61 
62 	if(argc > 0)
63 		getcaller(argv[0]);
64 
65 	dninit();
66 
67 	snprint(mntpt, sizeof(mntpt), "/net%s", ext);
68 	if(myipaddr(ipaddr, mntpt) < 0)
69 		sysfatal("can't read my ip address");
70 	syslog(0, logfile, "dnstcp call from %s to %I", caller, ipaddr);
71 
72 	db2cache(1);
73 
74 	setjmp(req.mret);
75 	req.isslave = 0;
76 
77 	/* loop on requests */
78 	for(;; putactivity()){
79 		now = time(0);
80 		memset(&repmsg, 0, sizeof(repmsg));
81 		alarm(10*60*1000);
82 		len = readmsg(0, buf, sizeof(buf));
83 		alarm(0);
84 		if(len <= 0)
85 			break;
86 		getactivity(&req);
87 		req.aborttime = now + 15*Min;
88 		err = convM2DNS(buf, len, &reqmsg);
89 		if(err){
90 			syslog(0, logfile, "server: input error: %s from %I", err, buf);
91 			break;
92 		}
93 		if(reqmsg.qdcount < 1){
94 			syslog(0, logfile, "server: no questions from %I", buf);
95 			break;
96 		}
97 		if(reqmsg.flags & Fresp){
98 			syslog(0, logfile, "server: reply not request from %I", buf);
99 			break;
100 		}
101 		if((reqmsg.flags & Omask) != Oquery){
102 			syslog(0, logfile, "server: op %d from %I", reqmsg.flags & Omask, buf);
103 			break;
104 		}
105 
106 		if(debug)
107 			syslog(0, logfile, "%d: serve (%s) %d %s %s",
108 				req.id, caller,
109 				reqmsg.id,
110 				reqmsg.qd->owner->name,
111 				rrname(reqmsg.qd->type, tname, sizeof tname));
112 
113 		/* loop through each question */
114 		while(reqmsg.qd){
115 			if(reqmsg.qd->type == Taxfr){
116 				dnzone(&reqmsg, &repmsg, &req);
117 			} else {
118 				dnserver(&reqmsg, &repmsg, &req);
119 				reply(1, &repmsg, &req);
120 				rrfreelist(repmsg.qd);
121 				rrfreelist(repmsg.an);
122 				rrfreelist(repmsg.ns);
123 				rrfreelist(repmsg.ar);
124 			}
125 		}
126 
127 		rrfreelist(reqmsg.qd);
128 		rrfreelist(reqmsg.an);
129 		rrfreelist(reqmsg.ns);
130 		rrfreelist(reqmsg.ar);
131 
132 		if(req.isslave){
133 			putactivity();
134 			_exits(0);
135 		}
136 	}
137 	refreshmain(mntpt);
138 }
139 
140 static int
141 readmsg(int fd, uchar *buf, int max)
142 {
143 	int n;
144 	uchar x[2];
145 
146 	if(readn(fd, x, 2) != 2)
147 		return -1;
148 	n = (x[0]<<8) | x[1];
149 	if(n > max)
150 		return -1;
151 	if(readn(fd, buf, n) != n)
152 		return -1;
153 	return n;
154 }
155 
156 static void
157 reply(int fd, DNSmsg *rep, Request *req)
158 {
159 	int len, rv;
160 	char tname[32];
161 	uchar buf[4096];
162 	RR *rp;
163 
164 	if(debug){
165 		syslog(0, logfile, "%d: reply (%s) %s %s %ux",
166 			req->id, caller,
167 			rep->qd->owner->name,
168 			rrname(rep->qd->type, tname, sizeof tname),
169 			rep->flags);
170 		for(rp = rep->an; rp; rp = rp->next)
171 			syslog(0, logfile, "an %R", rp);
172 		for(rp = rep->ns; rp; rp = rp->next)
173 			syslog(0, logfile, "ns %R", rp);
174 		for(rp = rep->ar; rp; rp = rp->next)
175 			syslog(0, logfile, "ar %R", rp);
176 	}
177 
178 
179 	len = convDNS2M(rep, buf+2, sizeof(buf) - 2);
180 	if(len <= 0)
181 		abort(); /* "dnserver: converting reply" */;
182 	buf[0] = len>>8;
183 	buf[1] = len;
184 	rv = write(fd, buf, len+2);
185 	if(rv != len+2){
186 		syslog(0, logfile, "sending reply: %d instead of %d", rv, len+2);
187 		exits(0);
188 	}
189 }
190 
191 /*
192  *  Hash table for domain names.  The hash is based only on the
193  *  first element of the domain name.
194  */
195 extern DN	*ht[HTLEN];
196 
197 static int
198 numelem(char *name)
199 {
200 	int i;
201 
202 	i = 1;
203 	for(; *name; name++)
204 		if(*name == '.')
205 			i++;
206 	return i;
207 }
208 
209 int
210 inzone(DN *dp, char *name, int namelen, int depth)
211 {
212 	int n;
213 
214 	if(dp->name == 0)
215 		return 0;
216 	if(numelem(dp->name) != depth)
217 		return 0;
218 	n = strlen(dp->name);
219 	if(n < namelen)
220 		return 0;
221 	if(strcmp(name, dp->name + n - namelen) != 0)
222 		return 0;
223 	if(n > namelen && dp->name[n - namelen - 1] != '.')
224 		return 0;
225 	return 1;
226 }
227 
228 static void
229 dnzone(DNSmsg *reqp, DNSmsg *repp, Request *req)
230 {
231 	DN *dp, *ndp;
232 	RR r, *rp;
233 	int h, depth, found, nlen;
234 
235 	memset(repp, 0, sizeof(*repp));
236 	repp->id = reqp->id;
237 	repp->flags = Fauth | Fresp | Fcanrec | Oquery;
238 	repp->qd = reqp->qd;
239 	reqp->qd = reqp->qd->next;
240 	repp->qd->next = 0;
241 	dp = repp->qd->owner;
242 
243 	/* send the soa */
244 	repp->an = rrlookup(dp, Tsoa, NOneg);
245 	reply(1, repp, req);
246 	if(repp->an == 0)
247 		goto out;
248 	rrfreelist(repp->an);
249 
250 	nlen = strlen(dp->name);
251 
252 	/* construct a breadth first search of the name space (hard with a hash) */
253 	repp->an = &r;
254 	for(depth = numelem(dp->name); ; depth++){
255 		found = 0;
256 		for(h = 0; h < HTLEN; h++)
257 			for(ndp = ht[h]; ndp; ndp = ndp->next)
258 				if(inzone(ndp, dp->name, nlen, depth)){
259 					for(rp = ndp->rr; rp; rp = rp->next){
260 						/* there shouldn't be negatives, but just in case */
261 						if(rp->negative)
262 							continue;
263 
264 						/* don't send an soa's, ns's are enough */
265 						if(rp->type == Tsoa)
266 							continue;
267 
268 						r = *rp;
269 						r.next = 0;
270 						reply(1, repp, req);
271 					}
272 					found = 1;
273 				}
274 		if(!found)
275 			break;
276 	}
277 
278 	/* resend the soa */
279 	repp->an = rrlookup(dp, Tsoa, NOneg);
280 	reply(1, repp, req);
281 	rrfreelist(repp->an);
282 out:
283 	rrfree(repp->qd);
284 }
285 
286 static void
287 getcaller(char *dir)
288 {
289 	int fd, n;
290 	static char remote[128];
291 
292 	snprint(remote, sizeof(remote), "%s/remote", dir);
293 	fd = open(remote, OREAD);
294 	if(fd < 0)
295 		return;
296 	n = read(fd, remote, sizeof(remote)-1);
297 	close(fd);
298 	if(n <= 0)
299 		return;
300 	if(remote[n-1] == '\n')
301 		n--;
302 	remote[n] = 0;
303 	caller = remote;
304 }
305 
306 static void
307 refreshmain(char *net)
308 {
309 	int fd;
310 	char file[128];
311 
312 	snprint(file, sizeof(file), "%s/dns", net);
313 	if(debug)
314 		syslog(0, logfile, "refreshing %s", file);
315 	fd = open(file, ORDWR);
316 	if(fd < 0){
317 		syslog(0, logfile, "can't refresh %s", file);
318 		return;
319 	}
320 	fprint(fd, "refresh");
321 	close(fd);
322 }
323 
324 /*
325  *  the following varies between dnsdebug and dns
326  */
327 void
328 logreply(int id, uchar *addr, DNSmsg *mp)
329 {
330 	RR *rp;
331 
332 	syslog(0, LOG, "%d: rcvd %I flags:%s%s%s%s%s", id, addr,
333 		mp->flags & Fauth ? " auth" : "",
334 		mp->flags & Ftrunc ? " trunc" : "",
335 		mp->flags & Frecurse ? " rd" : "",
336 		mp->flags & Fcanrec ? " ra" : "",
337 		mp->flags & (Fauth|Rname) == (Fauth|Rname) ?
338 		" nx" : "");
339 	for(rp = mp->qd; rp != nil; rp = rp->next)
340 		syslog(0, LOG, "%d: rcvd %I qd %s", id, addr, rp->owner->name);
341 	for(rp = mp->an; rp != nil; rp = rp->next)
342 		syslog(0, LOG, "%d: rcvd %I an %R", id, addr, rp);
343 	for(rp = mp->ns; rp != nil; rp = rp->next)
344 		syslog(0, LOG, "%d: rcvd %I ns %R", id, addr, rp);
345 	for(rp = mp->ar; rp != nil; rp = rp->next)
346 		syslog(0, LOG, "%d: rcvd %I ar %R", id, addr, rp);
347 }
348 
349 void
350 logsend(int id, int subid, uchar *addr, char *sname, char *rname, int type)
351 {
352 	char buf[12];
353 
354 	syslog(0, LOG, "%d.%d: sending to %I/%s %s %s",
355 		id, subid, addr, sname, rname, rrname(type, buf, sizeof buf));
356 }
357 
358 RR*
359 getdnsservers(int class)
360 {
361 	return dnsservers(class);
362 }