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wgengine/wgcfg: recover from mismatched PublicKey/Endpoints

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In rare circumstances (tailscale/corp#3016), the PublicKey
and Endpoints can diverge.

This by itself doesn't cause any harm, but our early exit
in response did, because it prevented us from recovering from it.

Remove the early exit.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
This commit is contained in:
Josh Bleecher Snyder
2021-11-10 18:42:16 -08:00
committed by Josh Bleecher Snyder
parent 9fc4e876e3
commit 85184a58ed
7 changed files with 27 additions and 9 deletions
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14
wgengine/wgcfg/writer.go
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@@ -11,13 +11,14 @@ import (
"inet.af/netaddr"
"tailscale.com/types/key"
"tailscale.com/types/logger"
)
// ToUAPI writes cfg in UAPI format to w.
// Prev is the previous device Config.
// Prev is required so that we can remove now-defunct peers
// without having to remove and re-add all peers.
func (cfg *Config) ToUAPI(w io.Writer, prev *Config) error {
func (cfg *Config) ToUAPI(logf logger.Logf, w io.Writer, prev *Config) error {
var stickyErr error
set := func(key, value string) {
if stickyErr != nil {
@@ -54,7 +55,16 @@ func (cfg *Config) ToUAPI(w io.Writer, prev *Config) error {
// Avoid setting endpoints if the correct one is already known
// to WireGuard, because doing so generates a bit more work in
// calling magicsock's ParseEndpoint for effectively a no-op.
if !wasPresent {
if oldPeer.WGEndpoint != p.PublicKey {
if wasPresent {
// We had an endpoint, and it was wrong.
// By construction, this should not happen.
// If it does, keep going so that we can recover from it,
// but log so that we know about it,
// because it is an indicator of other failed invariants.
// See corp issue 3016.
logf("[unexpected] endpoint changed from %s to %s", oldPeer.WGEndpoint, p.PublicKey)
}
set("endpoint", p.PublicKey.UntypedHexString())
}