feat(proxy): add HTTP to HTTPS redirection support

server/proxy/idle_watcher.go

@@ -0,0 +1,47 @@
+package proxy
+
+import (
+	"sync/atomic"
+	"time"
+)
+
+// idleWatcher closes a proxied connection pair when no bytes have flowed in
+// either direction for the configured timeout. Without it, endpoints that
+// stay open at the TCP level but never send data again would pin the join
+// goroutines and their transfer buffers forever.
+type idleWatcher struct {
+	lastActive atomic.Int64 // unix nano of the last byte transferred
+	stopCh     chan struct{}
+}
+
+func startIdleWatcher(timeout time.Duration, closeFn func()) *idleWatcher {
+	w := &idleWatcher{stopCh: make(chan struct{})}
+	w.touch()
+
+	go func() {
+		timer := time.NewTimer(timeout)
+		defer timer.Stop()
+		for {
+			select {
+			case <-w.stopCh:
+				return
+			case <-timer.C:
+				idle := time.Since(time.Unix(0, w.lastActive.Load()))
+				if idle >= timeout {
+					closeFn()
+					return
+				}
+				timer.Reset(timeout - idle)
+			}
+		}
+	}()
+	return w
+}
+
+func (w *idleWatcher) touch() {
+	w.lastActive.Store(time.Now().UnixNano())
+}
+
+func (w *idleWatcher) stop() {
+	close(w.stopCh)
+}