From e7bfd556c079c8b5e7425aed44abc35925b24043 Mon Sep 17 00:00:00 2001 From: Simon Kelley 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 --- 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);