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From e7bfd556c079c8b5e7425aed44abc35925b24043 Mon Sep 17 00:00:00 2001
From: Simon Kelley <simon@thekelleys.org.uk>
Date: Mon, 31 Dec 2018 20:51:15 +0000
Subject: [PATCH 17/32] Alter DHCP address selection after DECLINE in
consec-addr mode. Avoid offering the same address after a recieving a DECLINE
message to stop an infinite protocol loop. This has long been done in default
address allocation mode: this adds similar behaviour when allocaing addresses
consecutively.
Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
---
src/dhcp.c | 13 +++++++++++++
src/dhcp6.c | 11 +++++++++--
2 files changed, 22 insertions(+), 2 deletions(-)
--- a/src/dhcp.c
+++ b/src/dhcp.c
@@ -754,6 +754,19 @@ int address_allocate(struct dhcp_context
if (addr.s_addr == d->router.s_addr)
break;
+ /* in consec-ip mode, skip addresses equal to
+ the number of addresses rejected by clients. This
+ should avoid the same client being offered the same
+ address after it has rjected it. */
+ if (option_bool(OPT_CONSEC_ADDR))
+ {
+ if (c->addr_epoch)
+ {
+ c->addr_epoch--;
+ d = context; /* d non-NULL skips the address. */
+ }
+ }
+
/* Addresses which end in .255 and .0 are broken in Windows even when using
supernetting. ie dhcp-range=192.168.0.1,192.168.1.254,255,255,254.0
then 192.168.0.255 is a valid IP address, but not for Windows as it's
--- a/src/dhcp6.c
+++ b/src/dhcp6.c
@@ -431,8 +431,15 @@ struct dhcp_context *address6_allocate(s
else
{
if (!temp_addr && option_bool(OPT_CONSEC_ADDR))
- /* seed is largest extant lease addr in this context */
- start = lease_find_max_addr6(c) + serial;
+ {
+ /* seed is largest extant lease addr in this context,
+ skip addresses equal to the number of addresses rejected
+ by clients. This should avoid the same client being offered the same
+ address after it has rjected it. */
+ start = lease_find_max_addr6(c) + serial + c->addr_epoch;
+ if (c->addr_epoch)
+ c->addr_epoch--;
+ }
else
{
u64 range = 1 + addr6part(&c->end6) - addr6part(&c->start6);
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