ref: 5c1feb0ef0b795e5de71e956f9ccddcd5c4b7f21
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(argc > 0)
getcaller(argv[0]);
cfg.inside = 1;
dninit();
if(*ext == '/')
snprint(mntpt, sizeof mntpt, "%s", ext);
else
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);
}