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- Secondary servers in a failover pair will now perform ddns removals if

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they had performed ddns updates on a lease that is expiring, or was
  released through the primary.  As part of the same fix, stale binding scopes
  will now be removed if a change in identity of a lease's active client is
  detected, rather than simply if a lease is noticed to have expired (which it
  may have expired without a failover server noticing in some situations).
  [ISC-Bugs #19826b]
This commit is contained in:
David Hankins 2009-07-22 17:00:01 +00:00
parent 32fd12cc74
commit b8d45c67ea
3 changed files with 70 additions and 3 deletions
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7
RELNOTES
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@ -171,6 +171,13 @@ work on other platforms. Please report any problems and suggested fixes to
- Don't look for IPv6 interfaces on Linux when running in DHCPv4 mode.
Thanks to patches from Matthew Newton and David Cantrell.
- Secondary servers in a failover pair will now perform ddns removals if
they had performed ddns updates on a lease that is expiring, or was
released through the primary. As part of the same fix, stale binding scopes
will now be removed if a change in identity of a lease's active client is
detected, rather than simply if a lease is noticed to have expired (which it
may have expired without a failover server noticing in some situations).
Changes since 4.1.0b1
- A missing "else" in dhcrelay.c could have caused an interface not to

51
server/failover.c
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@ -5016,6 +5016,8 @@ isc_result_t dhcp_failover_process_bind_update (dhcp_failover_state_t *state,
int new_binding_state;
int send_to_backup = 0;
int required_options;
isc_boolean_t chaddr_changed = ISC_FALSE;
isc_boolean_t ident_changed = ISC_FALSE;
/* Validate the binding update. */
required_options = FTB_ASSIGNED_IP_ADDRESS | FTB_BINDING_STATUS;
@ -5085,6 +5087,12 @@ isc_result_t dhcp_failover_process_bind_update (dhcp_failover_state_t *state,
message = "chaddr too long";
goto bad;
}
if ((lt->hardware_addr.hlen != msg->chaddr.count) ||
(memcmp(lt->hardware_addr.hbuf, msg->chaddr.data,
msg->chaddr.count) != 0))
chaddr_changed = ISC_TRUE;
lt -> hardware_addr.hlen = msg -> chaddr.count;
memcpy (lt -> hardware_addr.hbuf, msg -> chaddr.data,
msg -> chaddr.count);
@ -5095,6 +5103,7 @@ isc_result_t dhcp_failover_process_bind_update (dhcp_failover_state_t *state,
reason = FTR_MISSING_BINDINFO;
goto bad;
} else if (msg->binding_status == FTS_ABANDONED) {
chaddr_changed = ISC_TRUE;
lt->hardware_addr.hlen = 0;
if (lt->scope)
binding_scope_dereference(&lt->scope, MDL);
@ -5110,6 +5119,12 @@ isc_result_t dhcp_failover_process_bind_update (dhcp_failover_state_t *state,
goto bad;
}
if ((lt->uid_len != msg->client_identifier.count) ||
(lt->uid == NULL) || /* Sanity; should never happen. */
(memcmp(lt->uid, msg->client_identifier.data,
lt->uid_len) != 0))
ident_changed = ISC_TRUE;
lt->uid_len = msg->client_identifier.count;
/* Allocate the lt->uid buffer if we haven't already, or
@ -5138,15 +5153,45 @@ isc_result_t dhcp_failover_process_bind_update (dhcp_failover_state_t *state,
} else if (lt->uid && msg->binding_status != FTS_RESET &&
msg->binding_status != FTS_FREE &&
msg->binding_status != FTS_BACKUP) {
ident_changed = ISC_TRUE;
if (lt->uid != lt->uid_buf)
dfree (lt->uid, MDL);
lt->uid = NULL;
lt->uid_max = lt->uid_len = 0;
}
/* If the lease was expired, also remove the stale binding scope. */
if (lt->scope && lt->ends < cur_time)
binding_scope_dereference(&lt->scope, MDL);
/*
* A server's configuration can assign a 'binding scope';
*
* set var = "value";
*
* The problem with these binding scopes is that they are refreshed
* when the server processes a client's DHCP packet. A local binding
* scope is trash, then, when the lease has been assigned by the
* partner server. There is no real way to detect this, a peer may
* be updating us (as through potential conflict) with a binding we
* sent them, but we can trivially detect the /problematic/ case;
*
* lease is free.
* primary allocates lease to client A, assigns ddns name A.
* primary fails.
* secondary enters partner down.
* lease expires, and is set free.
* lease is allocated to client B and given ddns name B.
* primary recovers.
*
* The binding update in this case will be active->active, but the
* client identification on the lease will have changed. The ddns
* update on client A will have leaked if we just remove the binding
* scope blindly.
*/
if (msg->binding_status == FTS_ACTIVE &&
(chaddr_changed || ident_changed)) {
ddns_removals(lease, NULL);
if (lease->scope != NULL)
binding_scope_dereference(&lease->scope, MDL);
}
/* XXX Times may need to be adjusted based on clock skew! */
if (msg -> options_present & FTB_STOS) {

15
server/mdb.c
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@ -1462,6 +1462,21 @@ void make_binding_state_transition (struct lease *lease)
lease -> binding_state == FTS_ACTIVE &&
lease -> next_binding_state == FTS_RELEASED))) {
#if defined (NSUPDATE)
/*
* Note: ddns_removals() is also iterated when the lease
* enters state 'released' in 'release_lease()'. The below
* is caught when a peer receives a BNDUPD from a failover
* peer; it may not have received the client's release (it
* may have been offline).
*
* We could remove the call from release_lease() because
* it will also catch here on the originating server after the
* peer acknowledges the state change. However, there could
* be many hours inbetween, and in this case we /know/ the
* client is no longer using the lease when we receive the
* release message. This is not true of expiry, where the
* peer may have extended the lease.
*/
ddns_removals(lease, NULL);
#endif
if (lease -> on_release) {