Revert "ipn/ipnlocal: plumb ExitNodeDNSResolvers for IsWireGuardOnly exit nodes"

This reverts commit f6845b10f6.

Signed-off-by: Maisem Ali <maisem@tailscale.com>

ipn/ipnlocal/local.go

@@ -3320,13 +3320,6 @@ func dnsConfigForNetmap(nm *netmap.NetworkMap, peers map[tailcfg.NodeID]tailcfg.
 		return dcfg
 	}
 
-	// If we're using an exit node and that exit node is IsWireGuardOnly with
-	// ExitNodeDNSResolver set, then add that as the default.
-	if resolvers, ok := wireguardExitNodeDNSResolvers(nm, peers, prefs.ExitNodeID()); ok {
-		addDefault(resolvers)
-		return dcfg
-	}
-
 	addDefault(nm.DNS.Resolvers)
 	for suffix, resolvers := range nm.DNS.Routes {
 		fqdn, err := dnsname.ToFQDN(suffix)
@@ -4744,30 +4737,6 @@ func exitNodeCanProxyDNS(nm *netmap.NetworkMap, peers map[tailcfg.NodeID]tailcfg
 	return "", false
 }
 
-// wireguardExitNodeDNSResolvers returns the DNS resolvers to use for a
-// WireGuard-only exit node, if it has resolver addresses.
-func wireguardExitNodeDNSResolvers(nm *netmap.NetworkMap, peers map[tailcfg.NodeID]tailcfg.NodeView, exitNodeID tailcfg.StableNodeID) ([]*dnstype.Resolver, bool) {
-	if exitNodeID.IsZero() {
-		return nil, false
-	}
-
-	for _, p := range peers {
-		if p.StableID() == exitNodeID && p.IsWireGuardOnly() {
-			resolvers := p.ExitNodeDNSResolvers()
-			if !resolvers.IsNil() && resolvers.Len() > 0 {
-				copies := make([]*dnstype.Resolver, resolvers.Len())
-				for i := range resolvers.LenIter() {
-					copies[i] = resolvers.At(i).AsStruct()
-				}
-				return copies, true
-			}
-			return nil, false
-		}
-	}
-
-	return nil, false
-}
-
 func peerCanProxyDNS(p tailcfg.NodeView) bool {
 	if p.Cap() >= 26 {
 		// Actually added at 25

ipn/ipnlocal/local_test.go

@@ -22,7 +22,6 @@ import (
 	"tailscale.com/tailcfg"
 	"tailscale.com/tsd"
 	"tailscale.com/tstest"
-	"tailscale.com/types/dnstype"
 	"tailscale.com/types/key"
 	"tailscale.com/types/logger"
 	"tailscale.com/types/logid"
@@ -856,109 +855,3 @@ func TestUpdateNetmapDelta(t *testing.T) {
 		}
 	}
 }
-
-func TestWireguardExitNodeDNSResolvers(t *testing.T) {
-	type tc struct {
-		name          string
-		id            tailcfg.StableNodeID
-		peers         []*tailcfg.Node
-		wantOK        bool
-		wantResolvers []*dnstype.Resolver
-	}
-
-	tests := []tc{
-		{
-			name:          "no peers",
-			id:            "1",
-			wantOK:        false,
-			wantResolvers: nil,
-		},
-		{
-			name: "non wireguard peer",
-			id:   "1",
-			peers: []*tailcfg.Node{
-				{
-					ID:                   1,
-					StableID:             "1",
-					IsWireGuardOnly:      false,
-					ExitNodeDNSResolvers: []*dnstype.Resolver{{Addr: "dns.example.com"}},
-				},
-			},
-			wantOK:        false,
-			wantResolvers: nil,
-		},
-		{
-			name: "no matching IDs",
-			id:   "2",
-			peers: []*tailcfg.Node{
-				{
-					ID:                   1,
-					StableID:             "1",
-					IsWireGuardOnly:      true,
-					ExitNodeDNSResolvers: []*dnstype.Resolver{{Addr: "dns.example.com"}},
-				},
-			},
-			wantOK:        false,
-			wantResolvers: nil,
-		},
-		{
-			name: "wireguard peer",
-			id:   "1",
-			peers: []*tailcfg.Node{
-				{
-					ID:                   1,
-					StableID:             "1",
-					IsWireGuardOnly:      true,
-					ExitNodeDNSResolvers: []*dnstype.Resolver{{Addr: "dns.example.com"}},
-				},
-			},
-			wantOK:        true,
-			wantResolvers: []*dnstype.Resolver{{Addr: "dns.example.com"}},
-		},
-	}
-
-	for _, tc := range tests {
-		peers := peersMap(nodeViews(tc.peers))
-		nm := &netmap.NetworkMap{}
-		gotResolvers, gotOK := wireguardExitNodeDNSResolvers(nm, peers, tc.id)
-
-		if gotOK != tc.wantOK || !resolversEqual(gotResolvers, tc.wantResolvers) {
-			t.Errorf("case: %s: got %v, %v, want %v, %v", tc.name, gotOK, gotResolvers, tc.wantOK, tc.wantResolvers)
-		}
-	}
-}
-
-func TestDNSConfigForNetmapForWireguardExitNode(t *testing.T) {
-	resolvers := []*dnstype.Resolver{{Addr: "dns.example.com"}}
-	nm := &netmap.NetworkMap{}
-	peers := map[tailcfg.NodeID]tailcfg.NodeView{
-		1: (&tailcfg.Node{
-			ID:                   1,
-			StableID:             "1",
-			IsWireGuardOnly:      true,
-			ExitNodeDNSResolvers: resolvers,
-			Hostinfo:             (&tailcfg.Hostinfo{}).View(),
-		}).View(),
-	}
-	prefs := &ipn.Prefs{
-		ExitNodeID: "1",
-		CorpDNS:    true,
-	}
-
-	got := dnsConfigForNetmap(nm, peers, prefs.View(), t.Logf, "")
-	if !resolversEqual(got.DefaultResolvers, resolvers) {
-		t.Errorf("got %v, want %v", got.DefaultResolvers, resolvers)
-	}
-}
-
-func resolversEqual(a, b []*dnstype.Resolver) bool {
-	if len(a) != len(b) {
-		return false
-	}
-	for i := range a {
-		if !a[i].Equal(b[i]) {
-			return false
-		}
-	}
-	return true
-}