package/network/services/dnsmasq/patches/0017-Alter-DHCP-address-selection-after-DECLINE-in-consec.patch

   1 From e7bfd556c079c8b5e7425aed44abc35925b24043 Mon Sep 17 00:00:00 2001
   2 From: Simon Kelley <simon@thekelleys.org.uk>
   3 Date: Mon, 31 Dec 2018 20:51:15 +0000
   4 Subject: [PATCH 17/57] Alter DHCP address selection after DECLINE in
   5  consec-addr mode. Avoid offering the same address after a recieving a DECLINE
   6  message to stop an infinite protocol loop. This has long been done in default
   7  address allocation mode: this adds similar behaviour when allocaing addresses
   8  consecutively.
   9
  10 Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
  11 ---
  12  src/dhcp.c  | 13 +++++++++++++
  13  src/dhcp6.c | 11 +++++++++--
  14  2 files changed, 22 insertions(+), 2 deletions(-)
  15
  16 --- a/src/dhcp.c
  17 +++ b/src/dhcp.c
  18 @@ -754,6 +754,19 @@ int address_allocate(struct dhcp_context
  19               if (addr.s_addr == d->router.s_addr)
  20                 break;
  21
  22 +           /* in consec-ip mode, skip addresses equal to
  23 +              the number of addresses rejected by clients. This
  24 +              should avoid the same client being offered the same
  25 +              address after it has rjected it. */
  26 +           if (option_bool(OPT_CONSEC_ADDR))
  27 +             {
  28 +               if (c->addr_epoch)
  29 +                 {
  30 +                   c->addr_epoch--;
  31 +                   d = context; /* d non-NULL skips the address. */
  32 +                 }
  33 +             }
  34 +
  35             /* Addresses which end in .255 and .0 are broken in Windows even when using
  36                supernetting. ie dhcp-range=192.168.0.1,192.168.1.254,255,255,254.0
  37                then 192.168.0.255 is a valid IP address, but not for Windows as it's
  38 --- a/src/dhcp6.c
  39 +++ b/src/dhcp6.c
  40 @@ -431,8 +431,15 @@ struct dhcp_context *address6_allocate(s
  41        else
  42         {
  43           if (!temp_addr && option_bool(OPT_CONSEC_ADDR))
  44 -           /* seed is largest extant lease addr in this context */
  45 -           start = lease_find_max_addr6(c) + serial;
  46 +           {
  47 +             /* seed is largest extant lease addr in this context,
  48 +                skip addresses equal to the number of addresses rejected
  49 +                by clients. This should avoid the same client being offered the same
  50 +                address after it has rjected it. */
  51 +             start = lease_find_max_addr6(c) + serial + c->addr_epoch;
  52 +             if (c->addr_epoch)
  53 +               c->addr_epoch--;
  54 +           }
  55           else
  56             {
  57               u64 range = 1 + addr6part(&c->end6) - addr6part(&c->start6);