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fix: use TSMP ping for reachability, not latency (#11749)

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Use TSMP ping for reachability, but leave Disco ping for when we call Ping() since we often use that to determine whether we have a direct connection.

Also adds unit tests to make sure Ping() returns direct connection vs DERP correctly.
This commit is contained in:
Spike Curtis
2024-01-22 17:37:15 +04:00
committed by GitHub
parent 66f119bde8
commit 5388a1b6d7
2 changed files with 101 additions and 3 deletions
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14
tailnet/conn.go
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@ -374,9 +374,13 @@ func (c *Conn) Status() *ipnstate.Status {
// Ping sends a ping to the Wireguard engine.
// The bool returned is true if the ping was performed P2P.
func (c *Conn) Ping(ctx context.Context, ip netip.Addr) (time.Duration, bool, *ipnstate.PingResult, error) {
return c.pingWithType(ctx, ip, tailcfg.PingDisco)
}
func (c *Conn) pingWithType(ctx context.Context, ip netip.Addr, pt tailcfg.PingType) (time.Duration, bool, *ipnstate.PingResult, error) {
errCh := make(chan error, 1)
prChan := make(chan *ipnstate.PingResult, 1)
go c.wireguardEngine.Ping(ip, tailcfg.PingDisco, func(pr *ipnstate.PingResult) {
go c.wireguardEngine.Ping(ip, pt, func(pr *ipnstate.PingResult) {
if pr.Err != "" {
errCh <- xerrors.New(pr.Err)
return
@ -418,7 +422,13 @@ func (c *Conn) AwaitReachable(ctx context.Context, ip netip.Addr) bool {
ctx, cancel := context.WithTimeout(ctx, 5*time.Minute)
defer cancel()
_, _, _, err := c.Ping(ctx, ip)
// For reachability, we use TSMP ping, which pings at the IP layer, and
// therefore requires that wireguard and the netstack are up. If we
// don't wait for wireguard to be up, we could miss a handshake, and it
// might take 5 seconds for the handshake to be retried. A 5s initial
// round trip can set us up for poor TCP performance, since the initial
// round-trip-time sets the initial retransmit timeout.
_, _, _, err := c.pingWithType(ctx, ip, tailcfg.PingTSMP)
if err == nil {
completed()
}