wgengine, all: remove LazyWG, use wireguard-go callback API for on-demand peersbradfitz/rm_lazy_wg

Replace the UAPI text protocol-based wireguard configuration with
wireguard-go's new direct callback API (SetPeerLookupFunc,
SetPeerByIPPacketFunc, RemoveMatchingPeers, SetPrivateKey).

Instead of computing a trimmed wireguard config ahead of time upon
control plane updates and pushing it via UAPI, install callbacks so
wireguard-go creates peers on demand when packets arrive. This removes
all the LazyWG trimming machinery: idle peer tracking, activity maps,
noteRecvActivity callbacks, the KeepFullWGConfig control knob, and the
ts_omit_lazywg build tag.

For incoming packets, PeerLookupFunc answers wireguard-go's questions
about unknown public keys by looking up the peer in the full config.
For outgoing packets, PeerByIPPacketFunc (installed from
LocalBackend.lookupPeerByIP) maps destination IPs to node public keys
using the existing nodeByAddr index.

Updates tailscale/corp#12345

Change-Id: I4cba80979ac49a1231d00a01fdba5f0c2af95dd8
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

1 files changed, 0 insertions, 13 deletions

diff --git a/feature/buildfeatures/feature_lazywg_enabled.go b/feature/buildfeatures/feature_lazywg_enabled.go
deleted file mode 100644
index f2d6a10f8..000000000
--- a/feature/buildfeatures/feature_lazywg_enabled.go
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright (c) Tailscale Inc & contributors
-// SPDX-License-Identifier: BSD-3-Clause
-
-// Code generated by gen.go; DO NOT EDIT.
-
-//go:build !ts_omit_lazywg
-
-package buildfeatures
-
-// HasLazyWG is whether the binary was built with support for modular feature "Lazy WireGuard configuration for memory-constrained devices with large netmaps".
-// Specifically, it's whether the binary was NOT built with the "ts_omit_lazywg" build tag.
-// It's a const so it can be used for dead code elimination.
-const HasLazyWG = true