tun/netstack: simplify read timeout on ping socket

I'm not 100% sure this is correct, but it certainly is a lot simpler.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

diff --git a/tun/netstack/tun.go b/tun/netstack/tun.go
index 97983b415f2d63ed824cc04a519fece84df2ebd6..94d63a607769bf7fa42b6bf56808065e6f7d04a7 100644 (file)
--- a/tun/netstack/tun.go
+++ b/tun/netstack/tun.go
@@ -17,7 +17,6 @@ import (
        "regexp"
        "strconv"
        "strings"
-       "sync"
        "time"
 
        "golang.zx2c4.com/go118/netip"
@@ -294,13 +293,11 @@ func (net *Net) ListenUDP(laddr *net.UDPAddr) (*gonet.UDPConn, error) {
 }
 
 type PingConn struct {
-       laddr           PingAddr
-       raddr           PingAddr
-       wq              waiter.Queue
-       ep              tcpip.Endpoint
-       mu              sync.RWMutex
-       deadline        time.Time
-       deadlineBreaker chan struct{}
+       laddr    PingAddr
+       raddr    PingAddr
+       wq       waiter.Queue
+       ep       tcpip.Endpoint
+       deadline *time.Timer
 }
 
 type PingAddr struct{ addr netip.Addr }
@@ -348,9 +345,10 @@ func (net *Net) DialPingAddr(laddr, raddr netip.Addr) (*PingConn, error) {
        }
 
        pc := &PingConn{
-               laddr:           PingAddr{laddr},
-               deadlineBreaker: make(chan struct{}, 1),
+               laddr:    PingAddr{laddr},
+               deadline: time.NewTimer(time.Hour << 10),
        }
+       pc.deadline.Stop()
 
        ep, tcpipErr := net.stack.NewEndpoint(tn, pn, &pc.wq)
        if tcpipErr != nil {
@@ -408,7 +406,7 @@ func (pc *PingConn) RemoteAddr() net.Addr {
 }
 
 func (pc *PingConn) Close() error {
-       close(pc.deadlineBreaker)
+       pc.deadline.Reset(0)
        pc.ep.Close()
        return nil
 }
@@ -454,33 +452,10 @@ func (pc *PingConn) ReadFrom(p []byte) (n int, addr net.Addr, err error) {
        pc.wq.EventRegister(&e, waiter.EventIn)
        defer pc.wq.EventUnregister(&e)
 
-       ready := false
-
-       for !ready {
-               pc.mu.RLock()
-               deadlineBreaker := pc.deadlineBreaker
-               deadline := pc.deadline
-               pc.mu.RUnlock()
-
-               if deadline.IsZero() {
-                       select {
-                       case <-deadlineBreaker:
-                       case <-notifyCh:
-                               ready = true
-                       }
-               } else {
-                       t := time.NewTimer(deadline.Sub(time.Now()))
-                       defer t.Stop()
-
-                       select {
-                       case <-t.C:
-                               return 0, nil, os.ErrDeadlineExceeded
-
-                       case <-deadlineBreaker:
-                       case <-notifyCh:
-                               ready = true
-                       }
-               }
+       select {
+       case <-pc.deadline.C:
+               return 0, nil, os.ErrDeadlineExceeded
+       case <-notifyCh:
        }
 
        w := tcpip.SliceWriter(p)
@@ -508,11 +483,7 @@ func (pc *PingConn) SetDeadline(t time.Time) error {
 }
 
 func (pc *PingConn) SetReadDeadline(t time.Time) error {
-       pc.mu.Lock()
-       defer pc.mu.Unlock()
-       close(pc.deadlineBreaker)
-       pc.deadlineBreaker = make(chan struct{}, 1)
-       pc.deadline = t
+       pc.deadline.Reset(t.Sub(time.Now()))
        return nil
 }