diff options
Diffstat (limited to 'src/libndb/dnsquery.c')
-rw-r--r-- | src/libndb/dnsquery.c | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/src/libndb/dnsquery.c b/src/libndb/dnsquery.c new file mode 100644 index 00000000..4cf8735a --- /dev/null +++ b/src/libndb/dnsquery.c @@ -0,0 +1,156 @@ +#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; +} |