Probe for another path when a keepalive punch finds a tunnel's remote unreachable

udp/unreachable_test.go

@@ -0,0 +1,37 @@
+//go:build !windows
+
+package udp
+
+import (
+	"net"
+	"syscall"
+	"testing"
+)
+
+func TestIsUnreachable(t *testing.T) {
+	wrap := func(err error) error { return &net.OpError{Op: "write", Net: "udp", Err: err} }
+
+	for _, err := range []error{
+		wrap(syscall.ENETUNREACH),
+		wrap(syscall.EHOSTUNREACH),
+		wrap(syscall.EADDRNOTAVAIL),
+		wrap(syscall.EAFNOSUPPORT),
+		ErrInvalidIPv6RemoteForSocket,
+	} {
+		if !IsUnreachable(err) {
+			t.Errorf("IsUnreachable(%v) = false, want true", err)
+		}
+	}
+
+	for _, err := range []error{
+		nil,
+		wrap(syscall.EPERM),
+		wrap(syscall.ENOBUFS),
+		wrap(syscall.EMSGSIZE),
+		net.ErrClosed,
+	} {
+		if IsUnreachable(err) {
+			t.Errorf("IsUnreachable(%v) = true, want false", err)
+		}
+	}
+}