#include #include #include #include #include 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 */ 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); /* * TODO: make fd static and keep it open to reduce 9P traffic * walking to /net*^/dns. Must be prepared to re-open it on error. */ 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(cistrstr(ip, "in-addr.arpa") || cistrstr(ip, "ip6.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; }