In domain_from_dns(), when at the hostname is a FQHN
query the DNS server for the _nfsv4idmapdomain TXT
record. If the record exists, use that as the
NFSv4 domain.
Note, this query will only happen if the domain name
is not set in the /etc/idmapd.conf
Signed-off-by: Steve Dickson <steved@xxxxxxxxxx>
---
libnfsidmap.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 103 insertions(+), 1 deletion(-)
diff --git a/libnfsidmap.c b/libnfsidmap.c
index 2db4d13..7b8c0ed 100644
--- a/libnfsidmap.c
+++ b/libnfsidmap.c
@@ -53,6 +53,10 @@
#include <stdarg.h>
#include <dlfcn.h>
#include <ctype.h>
+#include <resolv.h>
+#include <arpa/nameser.h>
+#include <arpa/nameser_compat.h>
+
#include "nfsidmap.h"
#include "nfsidmap_internal.h"
#include "cfg.h"
@@ -79,6 +83,11 @@ gid_t nobody_gid = (gid_t)-1;
#define IDMAPD_DEFAULT_DOMAIN "localdomain"
#endif
+#ifndef NFS4DNSTXTREC
+#define NFS4DNSTXTREC "_nfsv4idmapdomain"
+#endif
+
+
/* Default logging fuction */
static void default_logger(const char *fmt, ...)
{
@@ -114,6 +123,93 @@ static int id_as_chars(char *name, uid_t *id)
return 1;
}
+static int dns_txt_query(char *domain, char **nfs4domain)
+{
+ char *txtname = NFS4DNSTXTREC;
+ char *msg, *answ, *eom, *mptr;
+ int len, status = -1;
+ HEADER *hdr;
+
+ msg = calloc(1, NS_MAXMSG);
+ if (msg == NULL)
+ return -1;
+
+ answ = calloc(1, NS_MAXMSG);
+ if (answ == NULL) {
+ free(msg);
+ return -1;
+ }
+
+ if (res_init() < 0) {
+ IDMAP_LOG(2, ("libnfsidmap: res_init() failed for %s.%s: %s\n",
+ txtname, domain, hstrerror(h_errno)));
+ goto freemem;
+ }
+ len = res_querydomain(txtname, domain, C_IN, T_TXT, msg, NS_MAXMSG);
+ if (len < 0) {
+ IDMAP_LOG(2, ("libnfsidmap: res_querydomain() failed for %s.%s: %s\n",
+ txtname, domain, hstrerror(h_errno)));
+ goto freemem;
+ }
+ hdr = (HEADER *)msg;
+
+ /* See if there is an answer */
+ if (ntohs(hdr->ancount) < 1) {
+ IDMAP_LOG(2, ("libnfsidmap: No TXT record for %s.%s\n",
+ txtname, domain));
+ goto freemem;
+ }
+ /* find the EndOfMessage */
+ eom = msg + len;
+
+ /* skip header */
+ mptr = &msg[HFIXEDSZ];
+
+ /* skip name field in question section */
+ mptr += dn_skipname(mptr, eom) + QFIXEDSZ;
+
+ /* read in the question */
+ len = dn_expand(msg, eom, mptr, answ, NS_MAXDNAME);
+ if (len < 0) { /* does this really matter?? */
+ IDMAP_LOG(2, ("libnfsidmap: No question section for %s.%s: %s\n",
+ txtname, domain, hstrerror(h_errno)));
+ goto freemem;
+ }
+
+ /*
+ * Now, dissect the answer section, Note: if there
+ * are more than one answer only the first
+ * one will be used.
+ */
+
+ /* skip passed the name field */
+ mptr += dn_skipname(mptr, eom);
+ /* skip pass the type class and ttl fields */
+ mptr += 2 + 2 + 4;
+
+ /* make sure there is some data */
+ GETSHORT(len, mptr);
+ if (len < 0) {
+ IDMAP_LOG(2, ("libnfsidmap: No data in answer for %s.%s\n",
+ txtname, domain));
+ goto freemem;
+ }
+ /* get the lenght field */
+ len = (int)*mptr++;
+ /* copy the data */
+ memcpy(answ, mptr, len);
+ answ[len] = '\0';
+
+ *nfs4domain = strdup(answ);
+ status = 0;
+
+freemem:
+ free(msg);
+ free(answ);
+
+ return (status);
+}
+
static int domain_from_dns(char **domain)
{
struct hostent *he;
@@ -125,7 +221,13 @@ static int domain_from_dns(char **domain)
return -1;
if ((c = strchr(he->h_name, '.')) == NULL || *++c == '\0')
return -1;
- *domain = strdup(c);
+ /*
+ * Query DNS to see if the _nfsv4idmapdomain TXT record exists
+ * If so use it...
+ */
+ if (dns_txt_query(c, domain) < 0)
+ *domain = strdup(c);
+
return 0;
}
--
2.7.4
--
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