363 lines
6.9 KiB
C
363 lines
6.9 KiB
C
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#include <u.h>
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#include <libc.h>
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#include <ip.h>
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#include "dns.h"
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enum
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{
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Maxpath= 128,
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};
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char *logfile = "dns";
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char *dbfile;
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int debug;
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int cachedb = 1;
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int testing;
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int traceactivity;
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int needrefresh;
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int resolver;
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char mntpt[Maxpath];
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char *caller = "";
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ulong now;
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int maxage;
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uchar ipaddr[IPaddrlen]; /* my ip address */
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char *LOG;
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char *zonerefreshprogram;
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static int readmsg(int, uchar*, int);
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static void reply(int, DNSmsg*, Request*);
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static void dnzone(DNSmsg*, DNSmsg*, Request*);
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static void getcaller(char*);
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static void refreshmain(char*);
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void
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main(int argc, char *argv[])
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{
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int len;
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Request req;
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DNSmsg reqmsg, repmsg;
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uchar buf[512];
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char tname[32];
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char *err;
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char *ext = "";
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ARGBEGIN{
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case 'd':
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debug++;
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break;
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case 'f':
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dbfile = ARGF();
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break;
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case 'r':
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resolver = 1;
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break;
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case 'x':
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ext = ARGF();
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break;
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}ARGEND
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if(debug < 2)
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debug = 0;
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if(argc > 0)
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getcaller(argv[0]);
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dninit();
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snprint(mntpt, sizeof(mntpt), "/net%s", ext);
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if(myipaddr(ipaddr, mntpt) < 0)
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sysfatal("can't read my ip address");
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syslog(0, logfile, "dnstcp call from %s to %I", caller, ipaddr);
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db2cache(1);
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setjmp(req.mret);
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req.isslave = 0;
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/* loop on requests */
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for(;; putactivity()){
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now = time(0);
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memset(&repmsg, 0, sizeof(repmsg));
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alarm(10*60*1000);
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len = readmsg(0, buf, sizeof(buf));
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alarm(0);
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if(len <= 0)
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break;
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getactivity(&req);
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req.aborttime = now + 15*Min;
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err = convM2DNS(buf, len, &reqmsg);
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if(err){
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syslog(0, logfile, "server: input error: %s from %I", err, buf);
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break;
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}
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if(reqmsg.qdcount < 1){
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syslog(0, logfile, "server: no questions from %I", buf);
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break;
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}
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if(reqmsg.flags & Fresp){
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syslog(0, logfile, "server: reply not request from %I", buf);
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break;
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}
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if((reqmsg.flags & Omask) != Oquery){
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syslog(0, logfile, "server: op %d from %I", reqmsg.flags & Omask, buf);
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break;
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}
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if(debug)
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syslog(0, logfile, "%d: serve (%s) %d %s %s",
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req.id, caller,
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reqmsg.id,
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reqmsg.qd->owner->name,
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rrname(reqmsg.qd->type, tname, sizeof tname));
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/* loop through each question */
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while(reqmsg.qd){
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if(reqmsg.qd->type == Taxfr){
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dnzone(&reqmsg, &repmsg, &req);
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} else {
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dnserver(&reqmsg, &repmsg, &req);
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reply(1, &repmsg, &req);
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rrfreelist(repmsg.qd);
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rrfreelist(repmsg.an);
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rrfreelist(repmsg.ns);
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rrfreelist(repmsg.ar);
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}
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}
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rrfreelist(reqmsg.qd);
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rrfreelist(reqmsg.an);
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rrfreelist(reqmsg.ns);
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rrfreelist(reqmsg.ar);
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if(req.isslave){
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putactivity();
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_exits(0);
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}
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}
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refreshmain(mntpt);
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}
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static int
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readmsg(int fd, uchar *buf, int max)
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{
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int n;
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uchar x[2];
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if(readn(fd, x, 2) != 2)
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return -1;
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n = (x[0]<<8) | x[1];
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if(n > max)
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return -1;
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if(readn(fd, buf, n) != n)
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return -1;
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return n;
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}
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static void
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reply(int fd, DNSmsg *rep, Request *req)
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{
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int len, rv;
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char tname[32];
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uchar buf[4096];
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RR *rp;
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if(debug){
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syslog(0, logfile, "%d: reply (%s) %s %s %ux",
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req->id, caller,
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rep->qd->owner->name,
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rrname(rep->qd->type, tname, sizeof tname),
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rep->flags);
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for(rp = rep->an; rp; rp = rp->next)
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syslog(0, logfile, "an %R", rp);
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for(rp = rep->ns; rp; rp = rp->next)
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syslog(0, logfile, "ns %R", rp);
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for(rp = rep->ar; rp; rp = rp->next)
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syslog(0, logfile, "ar %R", rp);
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}
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len = convDNS2M(rep, buf+2, sizeof(buf) - 2);
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if(len <= 0)
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abort(); /* "dnserver: converting reply" */;
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buf[0] = len>>8;
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buf[1] = len;
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rv = write(fd, buf, len+2);
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if(rv != len+2){
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syslog(0, logfile, "sending reply: %d instead of %d", rv, len+2);
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exits(0);
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}
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}
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/*
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* Hash table for domain names. The hash is based only on the
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* first element of the domain name.
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*/
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extern DN *ht[HTLEN];
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static int
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numelem(char *name)
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{
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int i;
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i = 1;
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for(; *name; name++)
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if(*name == '.')
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i++;
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return i;
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}
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int
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inzone(DN *dp, char *name, int namelen, int depth)
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{
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int n;
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if(dp->name == 0)
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return 0;
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if(numelem(dp->name) != depth)
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return 0;
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n = strlen(dp->name);
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if(n < namelen)
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return 0;
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if(strcmp(name, dp->name + n - namelen) != 0)
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return 0;
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if(n > namelen && dp->name[n - namelen - 1] != '.')
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return 0;
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return 1;
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}
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static void
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dnzone(DNSmsg *reqp, DNSmsg *repp, Request *req)
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{
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DN *dp, *ndp;
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RR r, *rp;
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int h, depth, found, nlen;
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memset(repp, 0, sizeof(*repp));
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repp->id = reqp->id;
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repp->flags = Fauth | Fresp | Fcanrec | Oquery;
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repp->qd = reqp->qd;
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reqp->qd = reqp->qd->next;
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repp->qd->next = 0;
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dp = repp->qd->owner;
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/* send the soa */
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repp->an = rrlookup(dp, Tsoa, NOneg);
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reply(1, repp, req);
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if(repp->an == 0)
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goto out;
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rrfreelist(repp->an);
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nlen = strlen(dp->name);
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/* construct a breadth first search of the name space (hard with a hash) */
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repp->an = &r;
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for(depth = numelem(dp->name); ; depth++){
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found = 0;
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for(h = 0; h < HTLEN; h++)
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for(ndp = ht[h]; ndp; ndp = ndp->next)
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if(inzone(ndp, dp->name, nlen, depth)){
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for(rp = ndp->rr; rp; rp = rp->next){
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/* there shouldn't be negatives, but just in case */
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if(rp->negative)
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continue;
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/* don't send an soa's, ns's are enough */
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if(rp->type == Tsoa)
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continue;
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r = *rp;
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r.next = 0;
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reply(1, repp, req);
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}
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found = 1;
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}
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if(!found)
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break;
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}
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/* resend the soa */
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repp->an = rrlookup(dp, Tsoa, NOneg);
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reply(1, repp, req);
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rrfreelist(repp->an);
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out:
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rrfree(repp->qd);
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}
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static void
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getcaller(char *dir)
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{
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int fd, n;
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static char remote[128];
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snprint(remote, sizeof(remote), "%s/remote", dir);
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fd = open(remote, OREAD);
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if(fd < 0)
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return;
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n = read(fd, remote, sizeof(remote)-1);
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close(fd);
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if(n <= 0)
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return;
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if(remote[n-1] == '\n')
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n--;
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remote[n] = 0;
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caller = remote;
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}
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static void
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refreshmain(char *net)
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{
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int fd;
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char file[128];
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snprint(file, sizeof(file), "%s/dns", net);
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if(debug)
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syslog(0, logfile, "refreshing %s", file);
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fd = open(file, ORDWR);
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if(fd < 0){
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syslog(0, logfile, "can't refresh %s", file);
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return;
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}
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fprint(fd, "refresh");
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close(fd);
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}
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/*
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* the following varies between dnsdebug and dns
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*/
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void
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logreply(int id, uchar *addr, DNSmsg *mp)
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{
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RR *rp;
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syslog(0, LOG, "%d: rcvd %I flags:%s%s%s%s%s", id, addr,
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mp->flags & Fauth ? " auth" : "",
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mp->flags & Ftrunc ? " trunc" : "",
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mp->flags & Frecurse ? " rd" : "",
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mp->flags & Fcanrec ? " ra" : "",
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mp->flags & (Fauth|Rname) == (Fauth|Rname) ?
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" nx" : "");
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for(rp = mp->qd; rp != nil; rp = rp->next)
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syslog(0, LOG, "%d: rcvd %I qd %s", id, addr, rp->owner->name);
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for(rp = mp->an; rp != nil; rp = rp->next)
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syslog(0, LOG, "%d: rcvd %I an %R", id, addr, rp);
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for(rp = mp->ns; rp != nil; rp = rp->next)
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syslog(0, LOG, "%d: rcvd %I ns %R", id, addr, rp);
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for(rp = mp->ar; rp != nil; rp = rp->next)
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syslog(0, LOG, "%d: rcvd %I ar %R", id, addr, rp);
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}
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void
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logsend(int id, int subid, uchar *addr, char *sname, char *rname, int type)
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{
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char buf[12];
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syslog(0, LOG, "%d.%d: sending to %I/%s %s %s",
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id, subid, addr, sname, rname, rrname(type, buf, sizeof buf));
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}
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RR*
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getdnsservers(int class)
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{
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return dnsservers(class);
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}
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