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Modify determination of ttl to use for DDNS update [ISC-Bugs #21126]

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This commit is contained in:
Shawn Routhier 2010-05-27 17:19:26 +00:00
parent 600ee61905
commit 2b58b8650e
5 changed files with 62 additions and 7 deletions
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9
RELNOTES
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@ -66,7 +66,14 @@ work on other platforms. Please report any problems and suggested fixes to
- Add some debugging output for use with the DDNS code. [ISC-Bugs #20916]
- Fix the trace code to handle timing events better and to truncate a file
before using instead of overwriting it. [ISC-Bugs 20969]
before using instead of overwriting it. [ISC-Bugs #20969]
- Modify the determination of the default TTL to use for DDNS updates.
The user may still configure the ttl via ddns-ttl. The default for
both v4 and v6 is now 1/2 the (preferred) lease time with a limit. The
previous defaults (1/2 lease time without a limit for v4 and a default
value for v6) may be used by defining USE_OLD_DDNS_TTL in site.h
[ISC-Bugs #21126]
Changes since 4.2.0a2

3
includes/dhcpd.h
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@ -750,6 +750,9 @@ struct lease_state {
#if !defined (DEFAULT_DDNS_TTL)
# define DEFAULT_DDNS_TTL 3600
#endif
#if !defined (MAX_DEFAULT_DDNS_TTL)
# define MAX_DEFAULT_DDNS_TTL 3600
#endif
/* Client option names */

12
includes/site.h
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@ -200,3 +200,15 @@
traces. */
/* #define TRACING */
/* Define this if you want the server to use the previous behavior
when determining the DDNS TTL. If the user has specified a ddns-ttl
option that is used to detemine the ttl. (If the user specifies
an option that references the lease structure it is only usable
for v4. In that case v6 will use the default.) Otherwise when
defined the defaults are: v4 - 1/2 the lease time,
v6 - DEFAULT_DDNS_TTL. When undefined the defaults are 1/2 the
(preferred) lease time for both but with a cap on the maximum. */
/* #define USE_OLD_DDNS_TTL */

42
server/ddns.c
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@ -3,7 +3,9 @@
Dynamic DNS updates. */
/*
* Copyright (c) 2004-2007,2009 by Internet Systems Consortium, Inc. ("ISC")
*
* Copyright (c) 2009-2010 by Internet Systems Consortium, Inc. ("ISC")
* Copyright (c) 2004-2007 by Internet Systems Consortium, Inc. ("ISC")
* Copyright (c) 2000-2003 by Internet Software Consortium
*
* Permission to use, copy, modify, and distribute this software for any
@ -328,18 +330,50 @@ ddns_updates(struct packet *packet, struct lease *lease, struct lease *old,
/*
* Compute the RR TTL.
*
* We have two ways of computing the TTL.
* The old behavior was to allow for the customer to set up
* the option or to default things. For v4 this was 1/2
* of the lease time, for v6 this was DEFAULT_DDNS_TTL.
* The new behavior continues to allow the customer to set
* up an option but the defaults are a little different.
* We now use 1/2 of the (preferred) lease time for both
* v4 and v6 and cap them at a maximum value.
* If the customer chooses to use an experession that references
* part of the lease the v6 value will be the default as there
* isn't a lease available for v6.
*/
ddns_ttl = DEFAULT_DDNS_TTL;
if (lease != NULL) {
if (lease->ends <= cur_time) {
ddns_ttl = 0;
} else {
ddns_ttl = (lease->ends - cur_time)/2;
}
}
#ifndef USE_OLD_DDNS_TTL
else if (lease6 != NULL) {
ddns_ttl = lease6->prefer/2;
}
if (ddns_ttl > MAX_DEFAULT_DDNS_TTL) {
ddns_ttl = MAX_DEFAULT_DDNS_TTL;
}
#endif
if ((oc = lookup_option(&server_universe, options, SV_DDNS_TTL))) {
if (evaluate_option_cache(&d1, packet, lease, NULL,
packet->options, options, scope,
oc, MDL)) {
packet->options, options,
scope, oc, MDL)) {
if (d1.len == sizeof (u_int32_t))
ddns_cb->ttl = getULong (d1.data);
ddns_ttl = getULong (d1.data);
data_string_forget (&d1, MDL);
}
}
ddns_cb->ttl = ddns_ttl;
/*
* Compute the reverse IP name, starting with the domain name.
*/

3
server/dhcpd.c
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@ -3,7 +3,7 @@
DHCP Server Daemon. */
/*
* Copyright (c) 2004-2009 by Internet Systems Consortium, Inc. ("ISC")
* Copyright (c) 2004-2010 by Internet Systems Consortium, Inc. ("ISC")
* Copyright (c) 1996-2003 by Internet Software Consortium
*
* Permission to use, copy, modify, and distribute this software for any
@ -72,7 +72,6 @@ char std_nsupdate [] = " \n\
option server.ddns-hostname = \n\
pick (option fqdn.hostname, option host-name); \n\
option server.ddns-domainname = config-option domain-name; \n\
option server.ddns-ttl = encode-int(lease-time / 2, 32); \n\
option server.ddns-rev-domainname = \"in-addr.arpa.\";";
/* This is the old-style name service updater that is executed