ref: a291bbdeddfd41a2f0907ecbd7b819f0eedffdaf
dir: /sys/src/cmd/ndb/dns.c/
#include <u.h>
#include <libc.h>
#include <auth.h>
#include <fcall.h>
#include <bio.h>
#include <ip.h>
#include <pool.h>
#include "dns.h"
enum
{
Maxrequest= 1024,
Maxreply= 8192, /* was 512 */
Maxrrr= 32, /* was 16 */
Maxfdata= 8192,
Defmaxage= 60*60, /* default domain name max. age */
Qdir= 0,
Qdns= 1,
};
typedef struct Mfile Mfile;
typedef struct Job Job;
typedef struct Network Network;
int vers; /* incremented each clone/attach */
static volatile int stop;
/* holds data to be returned via read of /net/dns, perhaps multiple reads */
struct Mfile
{
Mfile *next; /* next free mfile */
char *user;
Qid qid;
int fid;
int type; /* reply type */
char reply[Maxreply];
ushort rr[Maxrrr]; /* offset of rr's */
ushort nrr; /* number of rr's */
};
/*
* active local requests
*/
struct Job
{
Job *next;
int flushed;
Fcall request;
Fcall reply;
};
Lock joblock;
Job *joblist;
struct {
Lock;
Mfile *inuse; /* active mfile's */
} mfalloc;
Cfg cfg;
int debug;
int maxage = Defmaxage;
int mfd[2];
int needrefresh;
ulong now;
vlong nowns;
int sendnotifies;
int testing;
char *trace;
int traceactivity;
char *zonerefreshprogram;
char *logfile = "dns"; /* or "dns.test" */
char *dbfile;
char *dnsuser;
char mntpt[Maxpath];
int addforwtarg(char *);
int fillreply(Mfile*, int);
void freejob(Job*);
void io(void);
void mountinit(char*, char*);
Job* newjob(void);
void rattach(Job*, Mfile*);
void rauth(Job*);
void rclunk(Job*, Mfile*);
void rcreate(Job*, Mfile*);
void rflush(Job*);
void ropen(Job*, Mfile*);
void rread(Job*, Mfile*);
void rremove(Job*, Mfile*);
void rstat(Job*, Mfile*);
void rversion(Job*);
char* rwalk(Job*, Mfile*);
void rwrite(Job*, Mfile*, Request*);
void rwstat(Job*, Mfile*);
void sendmsg(Job*, char*);
void setext(char*, int, char*);
static char *lookupquery(Job*, Mfile*, Request*, char*, char*, int, int);
static char *respond(Job*, Mfile*, RR*, char*, int, int);
void
usage(void)
{
fprint(2, "usage: %s [-FnorRst] [-a maxage] [-f ndb-file] [-N target] "
"[-T forwip] [-x netmtpt] [-z refreshprog]\n", argv0);
exits("usage");
}
void
main(int argc, char *argv[])
{
int kid, pid;
char servefile[Maxpath], ext[Maxpath];
Dir *dir;
setnetmtpt(mntpt, sizeof mntpt, nil);
ext[0] = 0;
ARGBEGIN{
case 'a':
maxage = atol(EARGF(usage()));
if (maxage <= 0)
maxage = Defmaxage;
break;
case 'd':
debug = 1;
traceactivity = 1;
break;
case 'f':
dbfile = EARGF(usage());
break;
case 'F':
cfg.justforw = cfg.resolver = 1;
break;
case 'n':
sendnotifies = 1;
break;
case 'N':
target = atol(EARGF(usage()));
if (target < 1000)
target = 1000;
break;
case 'o':
cfg.straddle = 1; /* straddle inside & outside networks */
break;
case 'r':
cfg.resolver = 1;
break;
case 'R':
norecursion = 1;
break;
case 's':
cfg.serve = 1; /* serve network */
cfg.cachedb = 1;
break;
case 't':
testing = 1;
break;
case 'T':
addforwtarg(EARGF(usage()));
break;
case 'x':
setnetmtpt(mntpt, sizeof mntpt, EARGF(usage()));
setext(ext, sizeof ext, mntpt);
break;
case 'z':
zonerefreshprogram = EARGF(usage());
break;
default:
usage();
break;
}ARGEND
if(argc != 0)
usage();
if(testing)
mainmem->flags |= POOL_NOREUSE | POOL_ANTAGONISM;
mainmem->flags |= POOL_ANTAGONISM;
rfork(RFREND|RFNOTEG);
cfg.inside = (*mntpt == '\0' || strcmp(mntpt, "/net") == 0);
/* start syslog before we fork */
fmtinstall('F', fcallfmt);
dninit();
dnslog("starting %s%sdns %s%s%son %s",
(cfg.straddle? "straddling ": ""),
(cfg.cachedb? "caching ": ""),
(cfg.serve? "udp server ": ""),
(cfg.justforw? "forwarding-only ": ""),
(cfg.resolver? "resolver ": ""), mntpt);
opendatabase();
now = time(nil); /* open time files before we fork */
nowns = nsec();
dnsuser = estrdup(getuser());
snprint(servefile, sizeof servefile, "#s/dns%s", ext);
dir = dirstat(servefile);
if (dir)
sysfatal("%s exists; another dns instance is running",
servefile);
free(dir);
// unmount(servefile, mntpt);
// remove(servefile);
mountinit(servefile, mntpt); /* forks, parent exits */
srand(now*getpid());
db2cache(1);
if (cfg.straddle && !seerootns())
dnslog("straddle server misconfigured; can't see root name servers");
/*
* fork without sharing heap.
* parent waits around for child to die, then forks & restarts.
* child may spawn udp server, notify procs, etc.; when it gets too
* big, it kills itself and any children.
* /srv/dns and /net/dns remain open and valid.
*/
for (;;) {
kid = rfork(RFPROC|RFFDG|RFNOTEG);
switch (kid) {
case -1:
sysfatal("fork failed: %r");
case 0:
if(cfg.serve)
dnudpserver(mntpt);
if(sendnotifies)
notifyproc();
io();
_exits("restart");
default:
while ((pid = waitpid()) != kid && pid != -1)
continue;
break;
}
dnslog("dns restarting");
}
}
/*
* if a mount point is specified, set the cs extension to be the mount point
* with '_'s replacing '/'s
*/
void
setext(char *ext, int n, char *p)
{
int i, c;
n--;
for(i = 0; i < n; i++){
c = p[i];
if(c == 0)
break;
if(c == '/')
c = '_';
ext[i] = c;
}
ext[i] = 0;
}
void
mountinit(char *service, char *mntpt)
{
int f;
int p[2];
char buf[32];
if(pipe(p) < 0)
sysfatal("pipe failed: %r");
/*
* make a /srv/dns
*/
if((f = create(service, OWRITE|ORCLOSE, 0666)) < 0)
sysfatal("create %s failed: %r", service);
snprint(buf, sizeof buf, "%d", p[1]);
if(write(f, buf, strlen(buf)) != strlen(buf))
sysfatal("write %s failed: %r", service);
/* copy namespace to avoid a deadlock */
switch(rfork(RFFDG|RFPROC|RFNAMEG)){
case 0: /* child: hang around and (re)start main proc */
close(p[1]);
procsetname("%s restarter", mntpt);
break;
case -1:
sysfatal("fork failed: %r");
default: /* parent: make /srv/dns, mount it, exit */
close(p[0]);
/*
* put ourselves into the file system
*/
if(mount(p[1], -1, mntpt, MAFTER, "") < 0)
fprint(2, "dns mount failed: %r\n");
_exits(0);
}
mfd[0] = mfd[1] = p[0];
}
Mfile*
newfid(int fid, int needunused)
{
Mfile *mf;
lock(&mfalloc);
for(mf = mfalloc.inuse; mf != nil; mf = mf->next)
if(mf->fid == fid){
unlock(&mfalloc);
if(needunused)
return nil;
return mf;
}
mf = emalloc(sizeof(*mf));
mf->fid = fid;
mf->user = estrdup("dummy");
mf->next = mfalloc.inuse;
mfalloc.inuse = mf;
unlock(&mfalloc);
return mf;
}
void
freefid(Mfile *mf)
{
Mfile **l;
lock(&mfalloc);
for(l = &mfalloc.inuse; *l != nil; l = &(*l)->next)
if(*l == mf){
*l = mf->next;
free(mf->user);
memset(mf, 0, sizeof *mf); /* cause trouble */
free(mf);
unlock(&mfalloc);
return;
}
unlock(&mfalloc);
sysfatal("freeing unused fid");
}
Mfile*
copyfid(Mfile *mf, int fid)
{
Mfile *nmf;
nmf = newfid(fid, 1);
if(nmf == nil)
return nil;
nmf->fid = fid;
free(nmf->user); /* estrdup("dummy") */
nmf->user = estrdup(mf->user);
nmf->qid.type = mf->qid.type;
nmf->qid.path = mf->qid.path;
nmf->qid.vers = vers++;
return nmf;
}
Job*
newjob(void)
{
Job *job;
job = emalloc(sizeof *job);
lock(&joblock);
job->next = joblist;
joblist = job;
job->request.tag = -1;
unlock(&joblock);
return job;
}
void
freejob(Job *job)
{
Job **l;
lock(&joblock);
for(l = &joblist; *l; l = &(*l)->next)
if(*l == job){
*l = job->next;
memset(job, 0, sizeof *job); /* cause trouble */
free(job);
break;
}
unlock(&joblock);
}
void
flushjob(int tag)
{
Job *job;
lock(&joblock);
for(job = joblist; job; job = job->next)
if(job->request.tag == tag && job->request.type != Tflush){
job->flushed = 1;
break;
}
unlock(&joblock);
}
void
io(void)
{
volatile long n;
volatile uchar mdata[IOHDRSZ + Maxfdata];
Job *volatile job;
Mfile *volatile mf;
volatile Request req;
memset(&req, 0, sizeof req);
/*
* a slave process is sometimes forked to wait for replies from other
* servers. The master process returns immediately via a longjmp
* through 'mret'.
*/
if(setjmp(req.mret))
putactivity(0);
req.isslave = 0;
stop = 0;
while(!stop){
procsetname("%d %s/dns Twrites of %d 9p rpcs read; %d alarms",
stats.qrecvd9p, mntpt, stats.qrecvd9prpc, stats.alarms);
while((n = read9pmsg(mfd[0], mdata, sizeof mdata)) == 0)
;
if(n < 0){
dnslog("error reading 9P from %s: %r", mntpt);
sleep(2000); /* don't thrash after read error */
return;
}
stats.qrecvd9prpc++;
job = newjob();
if(convM2S(mdata, n, &job->request) != n){
freejob(job);
continue;
}
mf = newfid(job->request.fid, 0);
if(debug)
dnslog("%F", &job->request);
getactivity(&req, 0);
req.aborttime = timems() + Maxreqtm;
req.from = "9p";
switch(job->request.type){
default:
warning("unknown request type %d", job->request.type);
break;
case Tversion:
rversion(job);
break;
case Tauth:
rauth(job);
break;
case Tflush:
rflush(job);
break;
case Tattach:
rattach(job, mf);
break;
case Twalk:
rwalk(job, mf);
break;
case Topen:
ropen(job, mf);
break;
case Tcreate:
rcreate(job, mf);
break;
case Tread:
rread(job, mf);
break;
case Twrite:
/* &req is handed to dnresolve() */
rwrite(job, mf, &req);
break;
case Tclunk:
rclunk(job, mf);
break;
case Tremove:
rremove(job, mf);
break;
case Tstat:
rstat(job, mf);
break;
case Twstat:
rwstat(job, mf);
break;
}
freejob(job);
/*
* slave processes die after replying
*/
if(req.isslave){
putactivity(0);
_exits(0);
}
putactivity(0);
}
/* kill any udp server, notifier, etc. processes */
postnote(PNGROUP, getpid(), "die");
sleep(1000);
}
void
rversion(Job *job)
{
if(job->request.msize > IOHDRSZ + Maxfdata)
job->reply.msize = IOHDRSZ + Maxfdata;
else
job->reply.msize = job->request.msize;
if(strncmp(job->request.version, "9P2000", 6) != 0)
sendmsg(job, "unknown 9P version");
else{
job->reply.version = "9P2000";
sendmsg(job, 0);
}
}
void
rauth(Job *job)
{
sendmsg(job, "dns: authentication not required");
}
/*
* don't flush till all the slaves are done
*/
void
rflush(Job *job)
{
flushjob(job->request.oldtag);
sendmsg(job, 0);
}
void
rattach(Job *job, Mfile *mf)
{
if(mf->user != nil)
free(mf->user);
mf->user = estrdup(job->request.uname);
mf->qid.vers = vers++;
mf->qid.type = QTDIR;
mf->qid.path = 0LL;
job->reply.qid = mf->qid;
sendmsg(job, 0);
}
char*
rwalk(Job *job, Mfile *mf)
{
int i, nelems;
char *err;
char **elems;
Mfile *nmf;
Qid qid;
err = 0;
nmf = nil;
elems = job->request.wname;
nelems = job->request.nwname;
job->reply.nwqid = 0;
if(job->request.newfid != job->request.fid){
/* clone fid */
nmf = copyfid(mf, job->request.newfid);
if(nmf == nil){
err = "clone bad newfid";
goto send;
}
mf = nmf;
}
/* else nmf will be nil */
qid = mf->qid;
if(nelems > 0)
/* walk fid */
for(i=0; i<nelems && i<MAXWELEM; i++){
if((qid.type & QTDIR) == 0){
err = "not a directory";
break;
}
if (strcmp(elems[i], "..") == 0 ||
strcmp(elems[i], ".") == 0){
qid.type = QTDIR;
qid.path = Qdir;
Found:
job->reply.wqid[i] = qid;
job->reply.nwqid++;
continue;
}
if(strcmp(elems[i], "dns") == 0){
qid.type = QTFILE;
qid.path = Qdns;
goto Found;
}
err = "file does not exist";
break;
}
send:
if(nmf != nil && (err!=nil || job->reply.nwqid<nelems))
freefid(nmf);
if(err == nil)
mf->qid = qid;
sendmsg(job, err);
return err;
}
void
ropen(Job *job, Mfile *mf)
{
int mode;
char *err;
err = 0;
mode = job->request.mode;
if(mf->qid.type & QTDIR)
if(mode)
err = "permission denied";
job->reply.qid = mf->qid;
job->reply.iounit = 0;
sendmsg(job, err);
}
void
rcreate(Job *job, Mfile *mf)
{
USED(mf);
sendmsg(job, "creation permission denied");
}
void
rread(Job *job, Mfile *mf)
{
int i, n;
long clock;
ulong cnt;
vlong off;
char *err;
uchar buf[Maxfdata];
Dir dir;
n = 0;
err = nil;
off = job->request.offset;
cnt = job->request.count;
*buf = '\0';
job->reply.data = (char*)buf;
if(mf->qid.type & QTDIR){
clock = time(nil);
if(off == 0){
memset(&dir, 0, sizeof dir);
dir.name = "dns";
dir.qid.type = QTFILE;
dir.qid.vers = vers;
dir.qid.path = Qdns;
dir.mode = 0666;
dir.length = 0;
dir.uid = dir.gid = dir.muid = mf->user;
dir.atime = dir.mtime = clock; /* wrong */
n = convD2M(&dir, buf, sizeof buf);
}
} else if (off < 0)
err = "negative read offset";
else {
/* first offset will always be zero */
for(i = 1; i <= mf->nrr; i++)
if(mf->rr[i] > off)
break;
if(i <= mf->nrr) {
if(off + cnt > mf->rr[i])
n = mf->rr[i] - off;
else
n = cnt;
assert(n >= 0);
job->reply.data = mf->reply + off;
}
}
job->reply.count = n;
sendmsg(job, err);
}
void
rwrite(Job *job, Mfile *mf, Request *req)
{
int rooted, wantsav, send;
ulong cnt;
char *err, *p, *atype;
char errbuf[ERRMAX];
err = nil;
cnt = job->request.count;
send = 1;
if(mf->qid.type & QTDIR)
err = "can't write directory";
else if (job->request.offset != 0)
err = "writing at non-zero offset";
else if(cnt >= Maxrequest)
err = "request too long";
else
send = 0;
if (send)
goto send;
job->request.data[cnt] = 0;
if(cnt > 0 && job->request.data[cnt-1] == '\n')
job->request.data[cnt-1] = 0;
if(strcmp(mf->user, "none") == 0 || strcmp(mf->user, dnsuser) != 0)
goto query; /* skip special commands if not owner */
/*
* special commands
*/
if(debug)
dnslog("rwrite got: %s", job->request.data);
send = 1;
if(strcmp(job->request.data, "debug")==0)
debug ^= 1;
else if(strcmp(job->request.data, "testing")==0)
testing ^= 1;
else if(strcmp(job->request.data, "dump")==0)
dndump("/lib/ndb/dnsdump");
else if(strcmp(job->request.data, "poolcheck")==0)
poolcheck(mainmem);
else if(strcmp(job->request.data, "refresh")==0)
needrefresh = 1;
else if(strcmp(job->request.data, "restart")==0)
stop = 1;
else if(strcmp(job->request.data, "stats")==0)
dnstats("/lib/ndb/dnsstats");
else if(strncmp(job->request.data, "target ", 7)==0){
target = atol(job->request.data + 7);
dnslog("target set to %ld", target);
} else
send = 0;
if (send)
goto send;
query:
/*
* kill previous reply
*/
mf->nrr = 0;
mf->rr[0] = 0;
/*
* break up request (into a name and a type)
*/
atype = strchr(job->request.data, ' ');
if(atype == 0){
snprint(errbuf, sizeof errbuf, "illegal request %s",
job->request.data);
err = errbuf;
goto send;
} else
*atype++ = 0;
/*
* tracing request
*/
if(strcmp(atype, "trace") == 0){
if(trace)
free(trace);
if(*job->request.data)
trace = estrdup(job->request.data);
else
trace = 0;
goto send;
}
/* normal request: domain [type] */
stats.qrecvd9p++;
mf->type = rrtype(atype);
if(mf->type < 0){
snprint(errbuf, sizeof errbuf, "unknown type %s", atype);
err = errbuf;
goto send;
}
p = atype - 2;
if(p >= job->request.data && *p == '.'){
rooted = 1;
*p = 0;
} else
rooted = 0;
p = job->request.data;
if(*p == '!'){
wantsav = 1;
p++;
} else
wantsav = 0;
err = lookupquery(job, mf, req, errbuf, p, wantsav, rooted);
send:
job->reply.count = cnt;
sendmsg(job, err);
}
/*
* dnsdebug calls
* rr = dnresolve(buf, Cin, type, &req, 0, 0, Recurse, rooted, 0);
* which generates a UDP query, which eventually calls
* dnserver(&reqmsg, &repmsg, &req, buf, rcode);
* which calls
* rp = dnresolve(name, Cin, type, req, &mp->an, 0, recurse, 1, 0);
*
* but here we just call dnresolve directly.
*/
static char *
lookupquery(Job *job, Mfile *mf, Request *req, char *errbuf, char *p,
int wantsav, int rooted)
{
int status;
RR *rp, *neg;
status = Rok;
rp = dnresolve(p, Cin, mf->type, req, 0, 0, Recurse, rooted, &status);
neg = rrremneg(&rp);
if(neg){
status = neg->negrcode;
rrfreelist(neg);
}
return respond(job, mf, rp, errbuf, status, wantsav);
}
static char *
respond(Job *job, Mfile *mf, RR *rp, char *errbuf, int status, int wantsav)
{
long n;
RR *tp;
if(rp == nil)
switch(status){
case Rname:
return "name does not exist";
case Rserver:
return "dns failure";
case Rok:
default:
snprint(errbuf, ERRMAX,
"resource does not exist; negrcode %d", status);
return errbuf;
}
lock(&joblock);
if(!job->flushed){
/* format data to be read later */
n = 0;
mf->nrr = 0;
for(tp = rp; mf->nrr < Maxrrr-1 && n < Maxreply && tp &&
tsame(mf->type, tp->type); tp = tp->next){
mf->rr[mf->nrr++] = n;
if(wantsav)
n += snprint(mf->reply+n, Maxreply-n, "%Q", tp);
else
n += snprint(mf->reply+n, Maxreply-n, "%R", tp);
}
mf->rr[mf->nrr] = n;
}
unlock(&joblock);
rrfreelist(rp);
return nil;
}
void
rclunk(Job *job, Mfile *mf)
{
freefid(mf);
sendmsg(job, 0);
}
void
rremove(Job *job, Mfile *mf)
{
USED(mf);
sendmsg(job, "remove permission denied");
}
void
rstat(Job *job, Mfile *mf)
{
Dir dir;
uchar buf[IOHDRSZ+Maxfdata];
memset(&dir, 0, sizeof dir);
if(mf->qid.type & QTDIR){
dir.name = ".";
dir.mode = DMDIR|0555;
} else {
dir.name = "dns";
dir.mode = 0666;
}
dir.qid = mf->qid;
dir.length = 0;
dir.uid = dir.gid = dir.muid = mf->user;
dir.atime = dir.mtime = time(nil);
job->reply.nstat = convD2M(&dir, buf, sizeof buf);
job->reply.stat = buf;
sendmsg(job, 0);
}
void
rwstat(Job *job, Mfile *mf)
{
USED(mf);
sendmsg(job, "wstat permission denied");
}
void
sendmsg(Job *job, char *err)
{
int n;
uchar mdata[IOHDRSZ + Maxfdata];
char ename[ERRMAX];
if(err){
job->reply.type = Rerror;
snprint(ename, sizeof ename, "dns: %s", err);
job->reply.ename = ename;
}else
job->reply.type = job->request.type+1;
job->reply.tag = job->request.tag;
n = convS2M(&job->reply, mdata, sizeof mdata);
if(n == 0){
warning("sendmsg convS2M of %F returns 0", &job->reply);
abort();
}
lock(&joblock);
if(job->flushed == 0)
if(write(mfd[1], mdata, n)!=n)
sysfatal("mount write");
unlock(&joblock);
if(debug)
dnslog("%F %d", &job->reply, n);
}
/*
* 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.%d: sending to %I/%s %s %s",
getpid(), id, subid, addr, sname, rname,
rrname(type, buf, sizeof buf));
}
RR*
getdnsservers(int class)
{
return dnsservers(class);
}