[master] Added configuration parameter, ping-cltt-secs (v4 operation only)

    Merges in rt36283.

RELNOTES

@@ -88,7 +88,13 @@ Consortium.  This product includes cryptographic software written
 by Eric Young (eay@cryptsoft.com).
 
 		Changes since 4.4.1 (New Features)
-- none
+
+- A new configuration parameter, ping-cltt-secs (v4 operation only), has
+  been added to allow the user to specify the number of seconds that must
+  elapse since CLTT before a ping check is conducted.  Prior to this, the
+  value was hard coded at 60 seconds. Please see the server man pages for
+  a more detailed discussion.
+  [ISC-Bugs #36283]
 
 		Changes since 4.4.1 (Bug Fixes)
 
@@ -100,7 +106,6 @@ by Eric Young (eay@cryptsoft.com).
 
 		Changes since 4.4.0 (New Features)
 - none
-
 		Changes since 4.4.0 (Bug Fixes)
 
 - A delayed-ack value of 0 (the default), now correctly disables the delayed

includes/dhcpd.h

@@ -815,11 +815,17 @@ struct lease_state {
 #define SV_RELEASE_ON_ROAM		95
 #define SV_LOCAL_ADDRESS6		96
 #define SV_BIND_LOCAL_ADDRESS6		97
+#define SV_PING_CLTT_SECS		98
 
 #if !defined (DEFAULT_PING_TIMEOUT)
 # define DEFAULT_PING_TIMEOUT 1
 #endif
 
+#if !defined (DEFAULT_PING_CLTT_SECS)
+# define DEFAULT_PING_CLTT_SECS 60  /* in seconds */
+#endif
+
+
 #if !defined (DEFAULT_DELAYED_ACK)
 # define DEFAULT_DELAYED_ACK 0  /* default 0 disables delayed acking */
 #endif

server/dhcpd.conf.5

@@ -3027,6 +3027,36 @@ checking - if its value is false, no ping check is done.
 .RE
 .PP
 The
+.I ping-cltt-secs
+statement
+.RS 0.25i
+.PP
+.B ping-cltt-secs
+.I seconds\fR\fB;\fR
+.PP
+The server will conduct a ping check if all the following conditions are true:
+.PP
+1. Ping checking is enabled.
+.PP
+2. The server is responding to a DISCOVER.
+.PP
+3. The lease to be offered is neither static nor active (i.e. still a valid
+lease).
+.PP
+4. And any of the following are true:
+    a. This will be the first offer of this lease (CLTT is 0).
+    b. The lease is being offered to a client other than its previous owner
+    c. The lease is being offered to its previous owner and more than
+    \fBping-cltt-secs\fR have elapsed since CLTT of the original lease.
+    d. The lease was abandoned and the server is attempting to reclaim it.
+
+.PP
+The \fBping-cltt-secs\fR statement allows the user to specify the amount of
+time that must elaspe after CLTT before a ping check will be conducted.
+The default value is sixty seconds.
+.RE
+.PP
+The
 .I ping-timeout
 statement
 .RS 0.25i

server/stables.c

@@ -291,6 +291,7 @@ static struct option server_options[] = {
 	{ "release-on-roam", "f",	&server_universe,  SV_RELEASE_ON_ROAM, 1 },
 	{ "local-address6", "6",	&server_universe,  SV_LOCAL_ADDRESS6, 1 },
 	{ "bind-local-address6", "f",	&server_universe,  SV_BIND_LOCAL_ADDRESS6, 1 },
+	{ "ping-cltt-secs", "T",	&server_universe,  SV_PING_CLTT_SECS, 1 },
 	{ NULL, NULL, NULL, 0, 0 }
 };