dnstcp.c 6.9 KB

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