From 66ad35c04e25f47445e6cd9df7ef8f5edd95a960 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@tailscale.com>
Date: Thu, 14 Oct 2021 13:09:06 -0700
Subject: [PATCH] ipn/ipnlocal: don't try to block localhost traffic when using
 exit nodes

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
(cherry picked from commit ddf3394b408b1dcc9d890234d5f24d5551ff4f0d)
---
 ipn/ipnlocal/local.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/ipn/ipnlocal/local.go b/ipn/ipnlocal/local.go
index 4a4cb0b6a..8cc5a2a14 100644
--- a/ipn/ipnlocal/local.go
+++ b/ipn/ipnlocal/local.go
@@ -1029,6 +1029,10 @@ func internalAndExternalInterfaces() (internal, external []netaddr.IPPrefix, err
 		if pfx.IsSingleIP() {
 			return
 		}
+		if iface.IsLoopback() {
+			internal = append(internal, pfx)
+			return
+		}
 		if runtime.GOOS == "windows" {
 			// Windows Hyper-V prefixes all MAC addresses with 00:15:5d.
 			// https://docs.microsoft.com/en-us/troubleshoot/windows-server/virtualization/default-limit-256-dynamic-mac-addresses