ref: dc593372bfc4224c6cf91d2031d0ad0aeadaddfe
dir: /sys/src/cmd/ndb/dntcpserver.c/
#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ndb.h>
#include <ip.h>
#include "dns.h"
enum {
Maxprocs = 64,
};
static int readmsg(int, uchar*, int);
static int reply(int, uchar *, DNSmsg*, Request*, uchar*);
static int dnzone(int, uchar *, DNSmsg*, DNSmsg*, Request*, uchar*);
static int tcpannounce(char *mntpt, char *addr, char caller[128]);
void
dntcpserver(char *mntpt, char *addr)
{
volatile int fd, len, rcode, rv;
volatile long ms;
volatile char caller[128];
volatile uchar pkt[Maxpkt], callip[IPaddrlen];
volatile DNSmsg reqmsg, repmsg;
volatile Request req;
volatile RR *edns;
char *volatile err;
/*
* fork sharing text, data, and bss with parent.
* stay in the same note group.
*/
switch(rfork(RFPROC|RFMEM|RFNOWAIT)){
case -1:
break;
case 0:
break;
default:
return;
}
procsetname("%s: tcp server %s", mntpt, addr);
if((fd = tcpannounce(mntpt, addr, caller)) < 0){
warning("can't announce %s on %s: %r", addr, mntpt);
_exits(0);
}
parseip(callip, caller);
procsetname("%s: tcp server %s serving %s", mntpt, addr, caller);
memset(&req, 0, sizeof req);
req.isslave = 1;
req.from = caller;
req.aborttime = timems() + Maxreqtm;
/* loop on requests */
for(;; putactivity(&req)){
memset(&reqmsg, 0, sizeof reqmsg);
edns = nil;
ms = (long)(req.aborttime - nowms);
if(ms < Minreqtm){
hangup:
close(fd);
_exits(0);
}
alarm(ms);
if(readn(fd, pkt, 2) != 2){
alarm(0);
goto hangup;
}
len = pkt[0]<<8 | pkt[1];
if(len <= 0 || len > Maxtcp || readn(fd, pkt+2, len) != len){
alarm(0);
goto hangup;
}
alarm(0);
getactivity(&req);
if((long)(req.aborttime - timems()) < Minreqtm)
break;
stats.qrecvdtcp++;
rcode = Rok;
err = convM2DNS(pkt+2, len, &reqmsg, &rcode);
if(err){
dnslog("%d: server: input err, len %d: %s from %s",
req.id, len, err, caller);
free(err);
break;
}
if(rcode == Rok)
if(reqmsg.qdcount < 1){
dnslog("%d: server: no questions from %s",
req.id, caller);
break;
} else if(reqmsg.flags & Fresp){
dnslog("%d: server: reply not request from %s",
req.id, caller);
break;
} else if((reqmsg.flags & Omask) != Oquery){
dnslog("%d: server: op %d from %s",
req.id, reqmsg.flags & Omask, caller);
break;
}
if(reqmsg.qd == nil){
dnslog("%d: server: no question RR from %s",
req.id, caller);
break;
}
logrequest(req.id, 0, "rcvd", callip, caller,
reqmsg.qd->owner->name, reqmsg.qd->type);
if(rcode == Rok)
if((reqmsg.edns = getednsopt(&reqmsg, &rcode)) != nil)
edns = mkednsopt();
/* loop through each question */
while(reqmsg.qd){
memset(&repmsg, 0, sizeof(repmsg));
repmsg.edns = edns;
if(rcode == Rok && reqmsg.qd->type == Taxfr)
rv = dnzone(fd, pkt, &reqmsg, &repmsg, &req, callip);
else {
dnserver(&reqmsg, &repmsg, &req, callip, rcode);
rv = reply(fd, pkt, &repmsg, &req, callip);
freeanswers(&repmsg);
}
if(rv < 0)
goto out;
}
rrfreelist(edns);
rrfreelist(reqmsg.edns);
freeanswers(&reqmsg);
}
out:
close(fd);
rrfreelist(edns);
rrfreelist(reqmsg.edns);
freeanswers(&reqmsg);
putactivity(&req);
_exits(0);
}
static int
reply(int fd, uchar *pkt, DNSmsg *rep, Request *req, uchar *callip)
{
int len, rv;
long ms;
/* taking too long */
ms = (long)(req->aborttime - nowms);
if(ms < 1)
return -1;
logreply(req->id, "send", callip, rep);
len = convDNS2M(rep, pkt+2, Maxtcp);
pkt[0] = len>>8;
pkt[1] = len;
len += 2;
alarm(ms);
rv = write(fd, pkt, len);
alarm(0);
if(rv != len){
dnslog("%d: error sending reply to %I: %r",
req->id, callip);
rv = -1;
}
return rv;
}
static Server*
findserver(uchar *callip, Server *servers, Request *req)
{
uchar ip[IPaddrlen];
RR *list, *rp;
for(; servers != nil; servers = servers->next){
if(strcmp(servers->name, "*") == 0)
return servers;
if(strcmp(ipattr(servers->name), "ip") == 0){
if(parseip(ip, servers->name) == -1)
continue;
if(ipcmp(callip, ip) == 0)
return servers;
continue;
}
list = dnresolve(servers->name, Cin,
isv4(callip)? Ta: Taaaa,
req, nil, 0, Recurse, 0, nil);
rrfreelist(rrremneg(&list));
for(rp = list; rp != nil; rp = rp->next){
if(parseip(ip, rp->ip->name) == -1)
continue;
if(ipcmp(callip, ip) == 0)
break;
}
rrfreelist(list);
if(rp != nil)
return servers;
}
return nil;
}
static int
dnzone(int fd, uchar *pkt, DNSmsg *reqp, DNSmsg *repp, Request *req, uchar *callip)
{
DN *dp;
RR *rp;
int rv;
repp->id = reqp->id;
repp->qd = reqp->qd;
reqp->qd = reqp->qd->next;
repp->qd->next = nil;
repp->flags = Fauth | Fresp | Oquery;
setercode(repp, Rok);
dp = repp->qd->owner;
/* send the soa */
repp->an = rrlookup(dp, Tsoa, NOneg);
if(repp->an != nil && !myip(callip)
&& findserver(callip, repp->an->soa->slaves, req) == nil){
dnslog("%d: dnzone: %I axfr %s - not a dnsslave",
req->id, callip, dp->name);
rrfreelist(repp->an);
repp->an = nil;
}
rv = reply(fd, pkt, repp, req, callip);
if(rv < 0 || repp->an == nil)
goto out;
rrfreelist(repp->an);
repp->an = nil;
repp->an = rrgetzone(dp->name);
while(repp->an != nil) {
rp = repp->an->next;
repp->an->next = nil;
rv = reply(fd, pkt, repp, req, callip);
rrfreelist(repp->an);
repp->an = rp;
if(rv < 0)
goto out;
}
/* resend the soa */
repp->an = rrlookup(dp, Tsoa, NOneg);
rv = reply(fd, pkt, repp, req, callip);
out:
rrfreelist(repp->an);
repp->an = nil;
rrfree(repp->qd);
repp->qd = nil;
return rv;
}
static int
tcpannounce(char *mntpt, char *addr, char caller[128])
{
char adir[NETPATHLEN], ldir[NETPATHLEN], buf[128];
int acfd, lcfd, dfd, wfd, rfd, procs;
/* announce tcp dns port */
snprint(buf, sizeof(buf), "%s/tcp!%s!53", mntpt, addr);
acfd = announce(buf, adir);
if(acfd < 0)
return -1;
/* open wait file to maintain child process count */
snprint(buf, sizeof(buf), "/proc/%d/wait", getpid());
wfd = open(buf, OREAD|OCEXEC);
if(wfd < 0){
close(acfd);
return -1;
}
procs = 0;
for(;;) {
if(procs >= Maxprocs || (procs % 8) == 0){
while(procs > 0){
if(procs < Maxprocs){
Dir *d = dirfstat(wfd);
if(d == nil || d->length == 0){
free(d);
break;
}
free(d);
}
if(read(wfd, buf, sizeof(buf)) <= 0){
procs = 0;
break;
}
procs--;
}
}
lcfd = listen(adir, ldir);
if(lcfd < 0){
close(wfd);
close(acfd);
return -1;
}
switch(rfork(RFPROC|RFMEM)){
case -1:
close(lcfd);
break;
case 0:
dfd = accept(lcfd, ldir);
close(lcfd);
if(dfd < 0)
_exits(0);
/* get the callers ip!port */
memset(caller, 0, 128);
snprint(buf, sizeof(buf), "%s/remote", ldir);
if((rfd = open(buf, OREAD|OCEXEC)) >= 0){
read(rfd, caller, 128-1);
close(rfd);
}
/* child returns */
return dfd;
default:
procs++;
}
}
}