Change the default behaviour of talk(1) to use "localhost" as the

"machine name" in ntalkd(8) request packets, when the destination
and source are local.

This should make talk(1) use much more pleasant for those security-
conscious individuals who have chosen to bind talkd to "localhost".

Previous to this change, talk(1) would require that the hostname of
the machine, as retrieved by gethostname(3), resolved to a valid and
reachable IPv4 address, using gethostbyname(3).

This makes talk(1) dependent on a valid host entry for "localhost"
in /etc/hosts (or the Domain Name System).

PR:		bin/23178
Submitted by:	angui.sh admin (with cleanups)

2 files changed, 18 insertions, 1 deletions

diff --git a/usr.bin/talk/get_names.c b/usr.bin/talk/get_names.c
index f2346ee729f41..ad6b8235eec19 100644
--- a/usr.bin/talk/get_names.c
+++ b/usr.bin/talk/get_names.c
@@ -90,7 +90,7 @@ get_names(argc, argv)
 	if (*cp == '\0') {
 		/* this is a local to local talk */
 		his_name = argv[1];
-		his_machine_name = my_machine_name;
+		my_machine_name = his_machine_name = "localhost";
 	} else {
 		if (*cp++ == '@') {
 			/* user@host */
diff --git a/usr.bin/talk/talk.1 b/usr.bin/talk/talk.1
index 18965c9b4d6d0..bbd5084530bcb 100644
--- a/usr.bin/talk/talk.1
+++ b/usr.bin/talk/talk.1
@@ -142,3 +142,20 @@ The
 .Nm
 command appeared in
 .Bx 4.2 .
+.Pp
+In
+.Fx 5.2 ,
+the default behaviour of
+.Nm
+was changed to treat local-to-local talk requests as originating
+and terminating at
+.Em localhost .
+Before this change, it was required that the hostname (as per
+.Xr gethostname 3 )
+resolved to a valid IPv4 address (via
+.Xr gethostbyname 3 ) ,
+making
+.Nm
+unsuitable for use in configurations where
+.Xr talkd 8
+was bound to the loopback interface (normally for security reasons).