Disable fallback DNS resolver

Author: nekohasekai

control/controlclient/direct.go

@@ -33,7 +33,6 @@ import (
 	"github.com/sagernet/tailscale/ipn/ipnstate"
 	"github.com/sagernet/tailscale/logtail"
 	"github.com/sagernet/tailscale/net/dnscache"
-	"github.com/sagernet/tailscale/net/dnsfallback"
 	"github.com/sagernet/tailscale/net/netmon"
 	"github.com/sagernet/tailscale/net/netutil"
 	"github.com/sagernet/tailscale/net/tlsdial"
@@ -249,11 +248,11 @@ func NewDirect(opts Options) (*Direct, error) {
 	}
 
 	dnsCache := &dnscache.Resolver{
-		Forward:          dnscache.Get().Forward, // use default cache's forwarder
-		UseLastGood:      true,
-		LookupIPFallback: dnsfallback.MakeLookupFunc(opts.Logf, netMon),
-		Logf:             opts.Logf,
-		LookupHook:       opts.LookupHook,
+		Forward:     dnscache.Get().Forward, // use default cache's forwarder
+		UseLastGood: true,
+		//LookupIPFallback: dnsfallback.MakeLookupFunc(opts.Logf, netMon),
+		Logf:       opts.Logf,
+		LookupHook: opts.LookupHook,
 	}
 
 	httpc := opts.HTTPTestClient

control/controlhttp/client.go

@@ -42,7 +42,6 @@ import (
 	"github.com/sagernet/tailscale/envknob"
 	"github.com/sagernet/tailscale/health"
 	"github.com/sagernet/tailscale/net/dnscache"
-	"github.com/sagernet/tailscale/net/dnsfallback"
 	"github.com/sagernet/tailscale/net/netutil"
 	"github.com/sagernet/tailscale/net/sockstats"
 	"github.com/sagernet/tailscale/net/tlsdial"
@@ -430,10 +429,10 @@ func (a *Dialer) resolver() *dnscache.Resolver {
 	}
 
 	return &dnscache.Resolver{
-		Forward:          dnscache.Get().Forward,
-		LookupIPFallback: dnsfallback.MakeLookupFunc(a.logf, a.NetMon),
-		UseLastGood:      true,
-		Logf:             a.Logf, // not a.logf method; we want to propagate nil-ness
+		Forward: dnscache.Get().Forward,
+		//LookupIPFallback: dnsfallback.MakeLookupFunc(a.logf, a.NetMon),
+		UseLastGood: true,
+		Logf:        a.Logf, // not a.logf method; we want to propagate nil-ness
 	}
 }
 

logpolicy/logpolicy.go

@@ -37,7 +37,6 @@ import (
 	"github.com/sagernet/tailscale/logtail"
 	"github.com/sagernet/tailscale/logtail/filch"
 	"github.com/sagernet/tailscale/net/dnscache"
-	"github.com/sagernet/tailscale/net/dnsfallback"
 	"github.com/sagernet/tailscale/net/netknob"
 	"github.com/sagernet/tailscale/net/netmon"
 	"github.com/sagernet/tailscale/net/netns"
@@ -798,9 +797,9 @@ func dialContext(ctx context.Context, netw, addr string, netMon *netmon.Monitor,
 	// If we failed to dial, try again with bootstrap DNS.
 	logf("logtail: dial %q failed: %v (in %v), trying bootstrap...", addr, err, d)
 	dnsCache := &dnscache.Resolver{
-		Forward:          dnscache.Get().Forward, // use default cache's forwarder
-		UseLastGood:      true,
-		LookupIPFallback: dnsfallback.MakeLookupFunc(logf, netMon),
+		Forward:     dnscache.Get().Forward, // use default cache's forwarder
+		UseLastGood: true,
+		//LookupIPFallback: dnsfallback.MakeLookupFunc(logf, netMon),
 	}
 	dialer := dnscache.Dialer(nd.DialContext, dnsCache)
 	c, err = dialer(ctx, netw, addr)