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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);
- ndbsetmalloctag(t, getcallerpc(&net));
- 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;
- }
- }
- ndbsetmalloctag(first, getcallerpc(&fd));
- return first;
- }
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