add -r flag to make mountd do reverse resolve of ipaddress on the fly

For those that want "traditional" showmount -a behavior from their mountd
(hostname:/path instead of ipaddr:/path). This patch adds a '-r' flag that
does a reverse-resolve for each IP address listed in the rmtab when
a dump operation is called.

Probably not a good idea for those concerned about performance, but since it's
not the default option, I don't see it being an issue.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Neil Brown <neilb@suse.de>

2 files changed, 18 insertions, 3 deletions

diff --git a/utils/mountd/mountd.c b/utils/mountd/mountd.c
index e151fa2..ee6afe6 100644
--- a/utils/mountd/mountd.c
+++ b/utils/mountd/mountd.c
@@ -37,6 +37,7 @@ static void		usage(const char *, int exitcode);
 static exports		get_exportlist(void);
 static struct nfs_fh_len *get_rootfh(struct svc_req *, dirpath *, mountstat3 *, int v3);
 
+int reverse_resolve = 0;
 int new_cache = 0;
 
 /* PRC: a high-availability callout program can be specified with -H
@@ -557,7 +558,7 @@ main(int argc, char **argv)
 
 	/* Parse the command line options and arguments. */
 	opterr = 0;
-	while ((c = getopt_long(argc, argv, "o:nFd:f:p:P:hH:N:V:vs:t:", longopts, NULL)) != EOF)
+	while ((c = getopt_long(argc, argv, "o:nFd:f:p:P:hH:N:V:vrs:t:", longopts, NULL)) != EOF)
 		switch (c) {
 		case 'o':
 			descriptors = atoi(optarg);
@@ -597,6 +598,9 @@ main(int argc, char **argv)
 		case 'n':
 			_rpcfdtype = SOCK_DGRAM;
 			break;
+		case 'r':
+			reverse_resolve = 1;
+			break;
 		case 's':
 			if ((state_dir = xstrdup(optarg)) == NULL) {
 				fprintf(stderr, "%s: xstrdup(%s) failed!\n",
diff --git a/utils/mountd/rmtab.c b/utils/mountd/rmtab.c
index f641a96..e8aff5a 100644
--- a/utils/mountd/rmtab.c
+++ b/utils/mountd/rmtab.c
@@ -25,6 +25,8 @@
 
 #include <limits.h> /* PATH_MAX */
 
+extern int reverse_resolve;
+
 /* If new path is a link do not destroy it but place the
  * file where the link points.
  */
@@ -185,6 +187,8 @@ mountlist_list(void)
 	struct rmtabent		*rep;
 	struct stat		stb;
 	int			lockid;
+	struct in_addr		addr;
+	struct hostent		*he;
 
 	if ((lockid = xflock(_PATH_RMTAB, "r")) < 0)
 		return NULL;
@@ -204,8 +208,15 @@ mountlist_list(void)
 		setrmtabent("r");
 		while ((rep = getrmtabent(1, NULL)) != NULL) {
 			m = (mountlist) xmalloc(sizeof(*m));
-			m->ml_hostname = xstrdup(rep->r_client);
-			m->ml_directory = xstrdup(rep->r_path);
+
+			if (reverse_resolve &&
+			   inet_aton((const char *) rep->r_client, &addr) &&
+			   (he = gethostbyaddr(&addr, sizeof(addr), AF_INET)))
+				m->ml_hostname = xstrdup(he->h_name);
+			else
+				m->ml_hostname = xstrdup(rep->r_client);
+
+ 			m->ml_directory = xstrdup(rep->r_path);
 			m->ml_next = mlist;
 			mlist = m;
 		}