dnstcp.c 7.4 KB

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  1. /*
  2. * dnstcp - serve dns via tcp
  3. */
  4. #include <u.h>
  5. #include <libc.h>
  6. #include <ip.h>
  7. #include "dns.h"
  8. Cfg cfg;
  9. char *caller = "";
  10. char *dbfile;
  11. int debug;
  12. uchar ipaddr[IPaddrlen]; /* my ip address */
  13. char *logfile = "dns";
  14. int maxage = 60*60;
  15. char mntpt[Maxpath];
  16. int needrefresh;
  17. ulong now;
  18. vlong nowns;
  19. int testing;
  20. int traceactivity;
  21. char *zonerefreshprogram;
  22. static int readmsg(int, uchar*, int);
  23. static void reply(int, DNSmsg*, Request*);
  24. static void dnzone(DNSmsg*, DNSmsg*, Request*);
  25. static void getcaller(char*);
  26. static void refreshmain(char*);
  27. void
  28. usage(void)
  29. {
  30. fprint(2, "usage: %s [-rR] [-f ndb-file] [-x netmtpt] [conndir]\n", argv0);
  31. exits("usage");
  32. }
  33. void
  34. main(int argc, char *argv[])
  35. {
  36. volatile int len, rcode;
  37. volatile char tname[32];
  38. char *volatile err, *volatile ext = "";
  39. volatile uchar buf[64*1024], callip[IPaddrlen];
  40. volatile DNSmsg reqmsg, repmsg;
  41. volatile Request req;
  42. alarm(2*60*1000);
  43. cfg.cachedb = 1;
  44. ARGBEGIN{
  45. case 'd':
  46. debug++;
  47. break;
  48. case 'f':
  49. dbfile = EARGF(usage());
  50. break;
  51. case 'r':
  52. cfg.resolver = 1;
  53. break;
  54. case 'R':
  55. norecursion = 1;
  56. break;
  57. case 'x':
  58. ext = EARGF(usage());
  59. break;
  60. default:
  61. usage();
  62. break;
  63. }ARGEND
  64. if(debug < 2)
  65. debug = 0;
  66. if(argc > 0)
  67. getcaller(argv[0]);
  68. cfg.inside = 1;
  69. dninit();
  70. snprint(mntpt, sizeof mntpt, "/net%s", ext);
  71. if(myipaddr(ipaddr, mntpt) < 0)
  72. sysfatal("can't read my ip address");
  73. dnslog("dnstcp call from %s to %I", caller, ipaddr);
  74. memset(callip, 0, sizeof callip);
  75. parseip(callip, caller);
  76. db2cache(1);
  77. memset(&req, 0, sizeof req);
  78. setjmp(req.mret);
  79. req.isslave = 0;
  80. procsetname("main loop");
  81. /* loop on requests */
  82. for(;; putactivity(0)){
  83. now = time(nil);
  84. memset(&repmsg, 0, sizeof repmsg);
  85. len = readmsg(0, buf, sizeof buf);
  86. if(len <= 0)
  87. break;
  88. getactivity(&req, 0);
  89. req.aborttime = now + 15*Min;
  90. rcode = 0;
  91. memset(&reqmsg, 0, sizeof reqmsg);
  92. err = convM2DNS(buf, len, &reqmsg, &rcode);
  93. if(err){
  94. dnslog("server: input error: %s from %s", err, caller);
  95. free(err);
  96. break;
  97. }
  98. if (rcode == 0)
  99. if(reqmsg.qdcount < 1){
  100. dnslog("server: no questions from %s", caller);
  101. break;
  102. } else if(reqmsg.flags & Fresp){
  103. dnslog("server: reply not request from %s",
  104. caller);
  105. break;
  106. } else if((reqmsg.flags & Omask) != Oquery){
  107. dnslog("server: op %d from %s",
  108. reqmsg.flags & Omask, caller);
  109. break;
  110. }
  111. if(debug)
  112. dnslog("[%d] %d: serve (%s) %d %s %s",
  113. getpid(), req.id, caller,
  114. reqmsg.id, reqmsg.qd->owner->name,
  115. rrname(reqmsg.qd->type, tname, sizeof tname));
  116. /* loop through each question */
  117. while(reqmsg.qd)
  118. if(reqmsg.qd->type == Taxfr)
  119. dnzone(&reqmsg, &repmsg, &req);
  120. else {
  121. dnserver(&reqmsg, &repmsg, &req, callip, rcode);
  122. reply(1, &repmsg, &req);
  123. rrfreelist(repmsg.qd);
  124. rrfreelist(repmsg.an);
  125. rrfreelist(repmsg.ns);
  126. rrfreelist(repmsg.ar);
  127. }
  128. rrfreelist(reqmsg.qd); /* qd will be nil */
  129. rrfreelist(reqmsg.an);
  130. rrfreelist(reqmsg.ns);
  131. rrfreelist(reqmsg.ar);
  132. if(req.isslave){
  133. putactivity(0);
  134. _exits(0);
  135. }
  136. }
  137. refreshmain(mntpt);
  138. }
  139. static int
  140. readmsg(int fd, uchar *buf, int max)
  141. {
  142. int n;
  143. uchar x[2];
  144. if(readn(fd, x, 2) != 2)
  145. return -1;
  146. n = x[0]<<8 | x[1];
  147. if(n > max)
  148. return -1;
  149. if(readn(fd, buf, n) != n)
  150. return -1;
  151. return n;
  152. }
  153. static void
  154. reply(int fd, DNSmsg *rep, Request *req)
  155. {
  156. int len, rv;
  157. char tname[32];
  158. uchar buf[64*1024];
  159. RR *rp;
  160. if(debug){
  161. dnslog("%d: reply (%s) %s %s %ux",
  162. req->id, caller,
  163. rep->qd->owner->name,
  164. rrname(rep->qd->type, tname, sizeof tname),
  165. rep->flags);
  166. for(rp = rep->an; rp; rp = rp->next)
  167. dnslog("an %R", rp);
  168. for(rp = rep->ns; rp; rp = rp->next)
  169. dnslog("ns %R", rp);
  170. for(rp = rep->ar; rp; rp = rp->next)
  171. dnslog("ar %R", rp);
  172. }
  173. len = convDNS2M(rep, buf+2, sizeof(buf) - 2);
  174. buf[0] = len>>8;
  175. buf[1] = len;
  176. rv = write(fd, buf, len+2);
  177. if(rv != len+2){
  178. dnslog("[%d] sending reply: %d instead of %d", getpid(), rv,
  179. len+2);
  180. exits(0);
  181. }
  182. }
  183. /*
  184. * Hash table for domain names. The hash is based only on the
  185. * first element of the domain name.
  186. */
  187. extern DN *ht[HTLEN];
  188. static int
  189. numelem(char *name)
  190. {
  191. int i;
  192. i = 1;
  193. for(; *name; name++)
  194. if(*name == '.')
  195. i++;
  196. return i;
  197. }
  198. int
  199. inzone(DN *dp, char *name, int namelen, int depth)
  200. {
  201. int n;
  202. if(dp->name == nil)
  203. return 0;
  204. if(numelem(dp->name) != depth)
  205. return 0;
  206. n = strlen(dp->name);
  207. if(n < namelen)
  208. return 0;
  209. if(strcmp(name, dp->name + n - namelen) != 0)
  210. return 0;
  211. if(n > namelen && dp->name[n - namelen - 1] != '.')
  212. return 0;
  213. return 1;
  214. }
  215. static void
  216. dnzone(DNSmsg *reqp, DNSmsg *repp, Request *req)
  217. {
  218. DN *dp, *ndp;
  219. RR r, *rp;
  220. int h, depth, found, nlen;
  221. memset(repp, 0, sizeof(*repp));
  222. repp->id = reqp->id;
  223. repp->qd = reqp->qd;
  224. reqp->qd = reqp->qd->next;
  225. repp->qd->next = 0;
  226. repp->flags = Fauth | Fresp | Oquery;
  227. if(!norecursion)
  228. repp->flags |= Fcanrec;
  229. dp = repp->qd->owner;
  230. /* send the soa */
  231. repp->an = rrlookup(dp, Tsoa, NOneg);
  232. reply(1, repp, req);
  233. if(repp->an == 0)
  234. goto out;
  235. rrfreelist(repp->an);
  236. repp->an = nil;
  237. nlen = strlen(dp->name);
  238. /* construct a breadth-first search of the name space (hard with a hash) */
  239. repp->an = &r;
  240. for(depth = numelem(dp->name); ; depth++){
  241. found = 0;
  242. for(h = 0; h < HTLEN; h++)
  243. for(ndp = ht[h]; ndp; ndp = ndp->next)
  244. if(inzone(ndp, dp->name, nlen, depth)){
  245. for(rp = ndp->rr; rp; rp = rp->next){
  246. /*
  247. * there shouldn't be negatives,
  248. * but just in case.
  249. * don't send any soa's,
  250. * ns's are enough.
  251. */
  252. if (rp->negative ||
  253. rp->type == Tsoa)
  254. continue;
  255. r = *rp;
  256. r.next = 0;
  257. reply(1, repp, req);
  258. }
  259. found = 1;
  260. }
  261. if(!found)
  262. break;
  263. }
  264. /* resend the soa */
  265. repp->an = rrlookup(dp, Tsoa, NOneg);
  266. reply(1, repp, req);
  267. rrfreelist(repp->an);
  268. repp->an = nil;
  269. out:
  270. rrfree(repp->qd);
  271. repp->qd = nil;
  272. }
  273. static void
  274. getcaller(char *dir)
  275. {
  276. int fd, n;
  277. static char remote[128];
  278. snprint(remote, sizeof(remote), "%s/remote", dir);
  279. fd = open(remote, OREAD);
  280. if(fd < 0)
  281. return;
  282. n = read(fd, remote, sizeof remote - 1);
  283. close(fd);
  284. if(n <= 0)
  285. return;
  286. if(remote[n-1] == '\n')
  287. n--;
  288. remote[n] = 0;
  289. caller = remote;
  290. }
  291. static void
  292. refreshmain(char *net)
  293. {
  294. int fd;
  295. char file[128];
  296. snprint(file, sizeof(file), "%s/dns", net);
  297. if(debug)
  298. dnslog("refreshing %s", file);
  299. fd = open(file, ORDWR);
  300. if(fd < 0)
  301. dnslog("can't refresh %s", file);
  302. else {
  303. fprint(fd, "refresh");
  304. close(fd);
  305. }
  306. }
  307. /*
  308. * the following varies between dnsdebug and dns
  309. */
  310. void
  311. logreply(int id, uchar *addr, DNSmsg *mp)
  312. {
  313. RR *rp;
  314. dnslog("%d: rcvd %I flags:%s%s%s%s%s", id, addr,
  315. mp->flags & Fauth? " auth": "",
  316. mp->flags & Ftrunc? " trunc": "",
  317. mp->flags & Frecurse? " rd": "",
  318. mp->flags & Fcanrec? " ra": "",
  319. (mp->flags & (Fauth|Rmask)) == (Fauth|Rname)? " nx": "");
  320. for(rp = mp->qd; rp != nil; rp = rp->next)
  321. dnslog("%d: rcvd %I qd %s", id, addr, rp->owner->name);
  322. for(rp = mp->an; rp != nil; rp = rp->next)
  323. dnslog("%d: rcvd %I an %R", id, addr, rp);
  324. for(rp = mp->ns; rp != nil; rp = rp->next)
  325. dnslog("%d: rcvd %I ns %R", id, addr, rp);
  326. for(rp = mp->ar; rp != nil; rp = rp->next)
  327. dnslog("%d: rcvd %I ar %R", id, addr, rp);
  328. }
  329. void
  330. logsend(int id, int subid, uchar *addr, char *sname, char *rname, int type)
  331. {
  332. char buf[12];
  333. dnslog("%d.%d: sending to %I/%s %s %s",
  334. id, subid, addr, sname, rname, rrname(type, buf, sizeof buf));
  335. }
  336. RR*
  337. getdnsservers(int class)
  338. {
  339. return dnsservers(class);
  340. }