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#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ndb.h>
#include <ndbhf.h>
static void nstrcpy(char*, char*, int);
static void mkptrname(char*, char*, int);
static Ndbtuple *doquery(int, char *dn, char *type);
/*
* search for a tuple that has the given 'attr=val' and also 'rattr=x'.
* copy 'x' into 'buf' and return the whole tuple.
*
* return 0 if not found.
*/
Ndbtuple*
dnsquery(char *net, char *val, char *type)
{
char rip[128];
char *p;
Ndbtuple *t;
int fd;
/* if the address is V4 or V6 null address, give up early vwhoi*/
if(strcmp(val, "::") == 0 || strcmp(val, "0.0.0.0") == 0)
return nil;
if(net == nil)
net = "/net";
snprint(rip, sizeof(rip), "%s/dns", net);
fd = open(rip, ORDWR);
if(fd < 0){
if(strcmp(net, "/net") == 0)
snprint(rip, sizeof(rip), "/srv/dns");
else {
snprint(rip, sizeof(rip), "/srv/dns%s", net);
p = strrchr(rip, '/');
*p = '_';
}
fd = open(rip, ORDWR);
if(fd < 0)
return nil;
if(mount(fd, -1, net, MBEFORE, "") < 0){
close(fd);
return nil;
}
/* fd is now closed */
snprint(rip, sizeof(rip), "%s/dns", net);
fd = open(rip, ORDWR);
if(fd < 0)
return nil;
}
/* zero out the error string */
werrstr("");
/* if this is a reverse lookup, first lookup the domain name */
if(strcmp(type, "ptr") == 0){
mkptrname(val, rip, sizeof rip);
t = doquery(fd, rip, "ptr");
} else
t = doquery(fd, val, type);
close(fd);
return t;
}
/*
* convert address into a reverse lookup address
*/
static void
mkptrname(char *ip, char *rip, int rlen)
{
char buf[128];
char *p, *np;
int len;
if(strstr(ip, "in-addr.arpa") || strstr(ip, "IN-ADDR.ARPA")){
nstrcpy(rip, ip, rlen);
return;
}
nstrcpy(buf, ip, sizeof buf);
for(p = buf; *p; p++)
;
*p = '.';
np = rip;
len = 0;
while(p >= buf){
len++;
p--;
if(*p == '.'){
memmove(np, p+1, len);
np += len;
len = 0;
}
}
memmove(np, p+1, len);
np += len;
strcpy(np, "in-addr.arpa");
}
static void
nstrcpy(char *to, char *from, int len)
{
strncpy(to, from, len);
to[len-1] = 0;
}
static Ndbtuple*
doquery(int fd, char *dn, char *type)
{
char buf[1024];
int n;
Ndbtuple *t, *first, *last;
seek(fd, 0, 0);
snprint(buf, sizeof(buf), "!%s %s", dn, type);
if(write(fd, buf, strlen(buf)) < 0)
return nil;
seek(fd, 0, 0);
first = last = nil;
for(;;){
n = read(fd, buf, sizeof(buf)-2);
if(n <= 0)
break;
if(buf[n-1] != '\n')
buf[n++] = '\n'; /* ndbparsline needs a trailing new line */
buf[n] = 0;
/* check for the error condition */
if(buf[0] == '!'){
werrstr("%s", buf+1);
return nil;
}
t = _ndbparseline(buf);
if(t != nil){
if(first)
last->entry = t;
else
first = t;
last = t;
while(last->entry)
last = last->entry;
}
}
setmalloctag(first, getcallerpc(&fd));
return first;
}
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