ref: 74d1f67b0547aa1b32648a2364f3cd6739d3e60a
dir: /sys/src/cmd/ndb/dnstcp.c/
/* * dnstcp - serve dns via tcp */ #include <u.h> #include <libc.h> #include <ip.h> #include "dns.h" Cfg cfg; char *caller = ""; char *dbfile; int debug; uchar ipaddr[IPaddrlen]; /* my ip address */ char *logfile = "dns"; int maxage = 60*60; char mntpt[Maxpath]; int needrefresh; ulong now; vlong nowns; int testing; int traceactivity; char *zonerefreshprogram; static int readmsg(int, uchar*, int); static void reply(int, DNSmsg*, Request*); static void dnzone(DNSmsg*, DNSmsg*, Request*); static void getcaller(char*); static void refreshmain(char*); void usage(void) { fprint(2, "usage: %s [-rR] [-f ndb-file] [-x netmtpt] [conndir]\n", argv0); exits("usage"); } void main(int argc, char *argv[]) { volatile int len, rcode; volatile char tname[32]; char *volatile err, *volatile ext = ""; volatile uchar buf[64*1024], callip[IPaddrlen]; volatile DNSmsg reqmsg, repmsg; volatile Request req; alarm(2*60*1000); cfg.cachedb = 1; ARGBEGIN{ case 'd': debug++; break; case 'f': dbfile = EARGF(usage()); break; case 'r': cfg.resolver = 1; break; case 'R': norecursion = 1; break; case 'x': ext = EARGF(usage()); break; default: usage(); break; }ARGEND if(debug < 2) debug = 0; if(argc > 0) getcaller(argv[0]); cfg.inside = 1; dninit(); snprint(mntpt, sizeof mntpt, "/net%s", ext); if(myipaddr(ipaddr, mntpt) < 0) sysfatal("can't read my ip address"); dnslog("dnstcp call from %s to %I", caller, ipaddr); memset(callip, 0, sizeof callip); parseip(callip, caller); db2cache(1); memset(&req, 0, sizeof req); setjmp(req.mret); req.isslave = 0; procsetname("main loop"); /* loop on requests */ for(;; putactivity(0)){ now = time(nil); memset(&repmsg, 0, sizeof repmsg); len = readmsg(0, buf, sizeof buf); if(len <= 0) break; getactivity(&req, 0); req.aborttime = timems() + S2MS(15*Min); rcode = 0; memset(&reqmsg, 0, sizeof reqmsg); err = convM2DNS(buf, len, &reqmsg, &rcode); if(err){ dnslog("server: input error: %s from %s", err, caller); free(err); break; } if (rcode == 0) if(reqmsg.qdcount < 1){ dnslog("server: no questions from %s", caller); break; } else if(reqmsg.flags & Fresp){ dnslog("server: reply not request from %s", caller); break; } else if((reqmsg.flags & Omask) != Oquery){ dnslog("server: op %d from %s", reqmsg.flags & Omask, caller); break; } if(reqmsg.qd == nil){ dnslog("server: no question RR from %s", caller); break; } if(debug) dnslog("[%d] %d: serve (%s) %d %s %s", getpid(), req.id, caller, reqmsg.id, reqmsg.qd->owner->name, rrname(reqmsg.qd->type, tname, sizeof tname)); /* loop through each question */ while(reqmsg.qd) if(reqmsg.qd->type == Taxfr) dnzone(&reqmsg, &repmsg, &req); else { dnserver(&reqmsg, &repmsg, &req, callip, rcode); reply(1, &repmsg, &req); rrfreelist(repmsg.qd); rrfreelist(repmsg.an); rrfreelist(repmsg.ns); rrfreelist(repmsg.ar); } rrfreelist(reqmsg.qd); /* qd will be nil */ rrfreelist(reqmsg.an); rrfreelist(reqmsg.ns); rrfreelist(reqmsg.ar); if(req.isslave){ putactivity(0); _exits(0); } } refreshmain(mntpt); } static int readmsg(int fd, uchar *buf, int max) { int n; uchar x[2]; if(readn(fd, x, 2) != 2) return -1; n = x[0]<<8 | x[1]; if(n > max) return -1; if(readn(fd, buf, n) != n) return -1; return n; } static void reply(int fd, DNSmsg *rep, Request *req) { int len, rv; char tname[32]; uchar buf[64*1024]; RR *rp; if(debug){ dnslog("%d: reply (%s) %s %s %ux", req->id, caller, rep->qd->owner->name, rrname(rep->qd->type, tname, sizeof tname), rep->flags); for(rp = rep->an; rp; rp = rp->next) dnslog("an %R", rp); for(rp = rep->ns; rp; rp = rp->next) dnslog("ns %R", rp); for(rp = rep->ar; rp; rp = rp->next) dnslog("ar %R", rp); } len = convDNS2M(rep, buf+2, sizeof(buf) - 2); buf[0] = len>>8; buf[1] = len; rv = write(fd, buf, len+2); if(rv != len+2){ dnslog("[%d] sending reply: %d instead of %d", getpid(), rv, len+2); exits(0); } } /* * Hash table for domain names. The hash is based only on the * first element of the domain name. */ extern DN *ht[HTLEN]; static int numelem(char *name) { int i; i = 1; for(; *name; name++) if(*name == '.') i++; return i; } int inzone(DN *dp, char *name, int namelen, int depth) { int n; if(dp->name == nil) return 0; if(numelem(dp->name) != depth) return 0; n = strlen(dp->name); if(n < namelen) return 0; if(cistrcmp(name, dp->name + n - namelen) != 0) return 0; if(n > namelen && dp->name[n - namelen - 1] != '.') return 0; return 1; } static void dnzone(DNSmsg *reqp, DNSmsg *repp, Request *req) { DN *dp, *ndp; RR r, *rp; int h, depth, found, nlen; memset(repp, 0, sizeof(*repp)); repp->id = reqp->id; repp->qd = reqp->qd; reqp->qd = reqp->qd->next; repp->qd->next = 0; repp->flags = Fauth | Fresp | Oquery; if(!norecursion) repp->flags |= Fcanrec; dp = repp->qd->owner; /* send the soa */ repp->an = rrlookup(dp, Tsoa, NOneg); reply(1, repp, req); if(repp->an == 0) goto out; rrfreelist(repp->an); repp->an = nil; nlen = strlen(dp->name); /* construct a breadth-first search of the name space (hard with a hash) */ repp->an = &r; for(depth = numelem(dp->name); ; depth++){ found = 0; for(h = 0; h < HTLEN; h++) for(ndp = ht[h]; ndp; ndp = ndp->next) if(inzone(ndp, dp->name, nlen, depth)){ for(rp = ndp->rr; rp; rp = rp->next){ /* * there shouldn't be negatives, * but just in case. * don't send any soa's, * ns's are enough. */ if (rp->negative || rp->type == Tsoa) continue; r = *rp; r.next = 0; reply(1, repp, req); } found = 1; } if(!found) break; } /* resend the soa */ repp->an = rrlookup(dp, Tsoa, NOneg); reply(1, repp, req); rrfreelist(repp->an); repp->an = nil; out: rrfree(repp->qd); repp->qd = nil; } static void getcaller(char *dir) { int fd, n; static char remote[128]; snprint(remote, sizeof(remote), "%s/remote", dir); fd = open(remote, OREAD); if(fd < 0) return; n = read(fd, remote, sizeof remote - 1); close(fd); if(n <= 0) return; if(remote[n-1] == '\n') n--; remote[n] = 0; caller = remote; } static void refreshmain(char *net) { int fd; char file[128]; snprint(file, sizeof(file), "%s/dns", net); if(debug) dnslog("refreshing %s", file); fd = open(file, ORDWR); if(fd < 0) dnslog("can't refresh %s", file); else { fprint(fd, "refresh"); close(fd); } } /* * the following varies between dnsdebug and dns */ void logreply(int id, uchar *addr, DNSmsg *mp) { RR *rp; dnslog("%d: rcvd %I flags:%s%s%s%s%s", id, addr, mp->flags & Fauth? " auth": "", mp->flags & Ftrunc? " trunc": "", mp->flags & Frecurse? " rd": "", mp->flags & Fcanrec? " ra": "", (mp->flags & (Fauth|Rmask)) == (Fauth|Rname)? " nx": ""); for(rp = mp->qd; rp != nil; rp = rp->next) dnslog("%d: rcvd %I qd %s", id, addr, rp->owner->name); for(rp = mp->an; rp != nil; rp = rp->next) dnslog("%d: rcvd %I an %R", id, addr, rp); for(rp = mp->ns; rp != nil; rp = rp->next) dnslog("%d: rcvd %I ns %R", id, addr, rp); for(rp = mp->ar; rp != nil; rp = rp->next) dnslog("%d: rcvd %I ar %R", id, addr, rp); } void logsend(int id, int subid, uchar *addr, char *sname, char *rname, int type) { char buf[12]; dnslog("%d.%d: sending to %I/%s %s %s", id, subid, addr, sname, rname, rrname(type, buf, sizeof buf)); } RR* getdnsservers(int class) { return dnsservers(class); }