ippool/ipv6pool: bitmap allocator + online reconfiguration

Replace the pre-generated free-list (one heap node per allocatable
address/prefix) with a per-pool bitmap. Each pool holds a list of
contiguous ranges, each range owning one bitmap (1 bit per unit);
a lease is a small per-session malloc wrapper around the ipdb item,
so pool memory is no longer shared or mutated by sessions.

Memory now scales with capacity at ~1 bit/unit instead of ~96B (v4) /
~128B (v6) per unit; startup, `show ippool`, and backup-restore are
O(1) instead of O(N)/O(N*M). Oversized IPv6 ranges (prefix_len-mask
> 24) are rejected at parse time instead of OOMing in the malloc loop.

The ipdb_t vtable, the owner-based put dispatch, ipdb.h structs, and
struct ap_session are unchanged; RADIUS and chap-secrets backends are
untouched (reconcile filters by owner).

Preserved behavior: p2p/net30 allocators (via a step/gw_offset/
peer_offset geometry triple), shuffle (randomized scan start), named
pools, next-chains, gw-ip-address, RADIUS pool-name attrs, and the
USE_BACKUP save/restore path. `gw=` is now accepted-and-ignored (its
per-address local gateway was already overridden at allocation time).

New: online reconfiguration. An EV_CONFIG_RELOAD handler rebuilds the
pool set and reconciles live sessions (sessions are the source of
truth, the bitmap is rebuilt from them) under
pool_set_rwlock(write) -> ses_lock(read) -> per-pool spinlock.
Sessions whose address left the pools are handled per a new
`reload-orphan = keep|disconnect` knob (default keep); foreign
in-range addresses are reserved to avoid duplicate assignment.

Adds extra/bitpool.h (shared bit-array helpers) and a standalone
extra/bitpool_test.c (not wired into cmake) covering the bitmap and
the v4/v6 address<->bit math, cross-checked against an __int128
reference.

Signed-off-by: Denys Fedoryshchenko <denys.f@collabora.com>

0 files changed, 0 insertions, 0 deletions