Revert "net: verify results from Lookup* are valid domain names"

rolandshoemaker · rolandshoemaker · commit fca7b8f3e690 · 2021-05-27T15:33:46.000Z
This reverts commit c89f122. Reason for revert: reverting so we can apply follow-up fixes and do a single cherry pick. Change-Id: I16c6283a0bcab056216f330fb98fa3b5f2b0780c Reviewed-on: https://go-review.googlesource.com/c/go/+/323129 Reviewed-by: Katie Hockman <katie@golang.org> Reviewed-by: Filippo Valsorda <filippo@golang.org> Trust: Katie Hockman <katie@golang.org> Run-TryBot: Katie Hockman <katie@golang.org> TryBot-Result: Go Bot <gobot@golang.org>
diff --git a/src/net/dnsclient_unix_test.go b/src/net/dnsclient_unix_test.go
@@ -1799,124 +1799,3 @@ func TestPTRandNonPTR(t *testing.T) {
 		t.Errorf("names = %q; want %q", names, want)
 	}
 }
-
-func TestCVE202133195(t *testing.T) {
-	fake := fakeDNSServer{
-		rh: func(n, _ string, q dnsmessage.Message, _ time.Time) (dnsmessage.Message, error) {
-			r := dnsmessage.Message{
-				Header: dnsmessage.Header{
-					ID:                 q.Header.ID,
-					Response:           true,
-					RCode:              dnsmessage.RCodeSuccess,
-					RecursionAvailable: true,
-				},
-				Questions: q.Questions,
-			}
-			switch q.Questions[0].Type {
-			case dnsmessage.TypeCNAME:
-				r.Answers = []dnsmessage.Resource{}
-			case dnsmessage.TypeA: // CNAME lookup uses a A/AAAA as a proxy
-				r.Answers = append(r.Answers,
-					dnsmessage.Resource{
-						Header: dnsmessage.ResourceHeader{
-							Name:   dnsmessage.MustNewName("<html>.golang.org."),
-							Type:   dnsmessage.TypeA,
-							Class:  dnsmessage.ClassINET,
-							Length: 4,
-						},
-						Body: &dnsmessage.AResource{
-							A: TestAddr,
-						},
-					},
-				)
-			case dnsmessage.TypeSRV:
-				n := q.Questions[0].Name
-				if n.String() == "_hdr._tcp.golang.org." {
-					n = dnsmessage.MustNewName("<html>.golang.org.")
-				}
-				r.Answers = append(r.Answers,
-					dnsmessage.Resource{
-						Header: dnsmessage.ResourceHeader{
-							Name:   n,
-							Type:   dnsmessage.TypeSRV,
-							Class:  dnsmessage.ClassINET,
-							Length: 4,
-						},
-						Body: &dnsmessage.SRVResource{
-							Target: dnsmessage.MustNewName("<html>.golang.org."),
-						},
-					},
-				)
-			case dnsmessage.TypeMX:
-				r.Answers = append(r.Answers,
-					dnsmessage.Resource{
-						Header: dnsmessage.ResourceHeader{
-							Name:   dnsmessage.MustNewName("<html>.golang.org."),
-							Type:   dnsmessage.TypeMX,
-							Class:  dnsmessage.ClassINET,
-							Length: 4,
-						},
-						Body: &dnsmessage.MXResource{
-							MX: dnsmessage.MustNewName("<html>.golang.org."),
-						},
-					},
-				)
-			case dnsmessage.TypeNS:
-				r.Answers = append(r.Answers,
-					dnsmessage.Resource{
-						Header: dnsmessage.ResourceHeader{
-							Name:   dnsmessage.MustNewName("<html>.golang.org."),
-							Type:   dnsmessage.TypeNS,
-							Class:  dnsmessage.ClassINET,
-							Length: 4,
-						},
-						Body: &dnsmessage.NSResource{
-							NS: dnsmessage.MustNewName("<html>.golang.org."),
-						},
-					},
-				)
-			case dnsmessage.TypePTR:
-				r.Answers = append(r.Answers,
-					dnsmessage.Resource{
-						Header: dnsmessage.ResourceHeader{
-							Name:   dnsmessage.MustNewName("<html>.golang.org."),
-							Type:   dnsmessage.TypePTR,
-							Class:  dnsmessage.ClassINET,
-							Length: 4,
-						},
-						Body: &dnsmessage.PTRResource{
-							PTR: dnsmessage.MustNewName("<html>.golang.org."),
-						},
-					},
-				)
-			}
-			return r, nil
-		},
-	}
-	r := Resolver{PreferGo: true, Dial: fake.DialContext}
-
-	_, err := r.LookupCNAME(context.Background(), "golang.org")
-	if expected := "lookup golang.org: CNAME target is invalid"; err.Error() != expected {
-		t.Errorf("LookupCNAME returned unexpected error, got %q, want %q", err.Error(), expected)
-	}
-	_, _, err = r.LookupSRV(context.Background(), "target", "tcp", "golang.org")
-	if expected := "lookup golang.org: SRV target is invalid"; err.Error() != expected {
-		t.Errorf("LookupSRV returned unexpected error, got %q, want %q", err.Error(), expected)
-	}
-	_, _, err = r.LookupSRV(context.Background(), "hdr", "tcp", "golang.org")
-	if expected := "lookup golang.org: SRV header name is invalid"; err.Error() != expected {
-		t.Errorf("LookupSRV returned unexpected error, got %q, want %q", err.Error(), expected)
-	}
-	_, err = r.LookupMX(context.Background(), "golang.org")
-	if expected := "lookup golang.org: MX target is invalid"; err.Error() != expected {
-		t.Errorf("LookupMX returned unexpected error, got %q, want %q", err.Error(), expected)
-	}
-	_, err = r.LookupNS(context.Background(), "golang.org")
-	if expected := "lookup golang.org: NS target is invalid"; err.Error() != expected {
-		t.Errorf("LookupNS returned unexpected error, got %q, want %q", err.Error(), expected)
-	}
-	_, err = r.LookupAddr(context.Background(), "1.2.3.4")
-	if expected := "lookup 1.2.3.4: PTR target is invalid"; err.Error() != expected {
-		t.Errorf("LookupAddr returned unexpected error, got %q, want %q", err.Error(), expected)
-	}
-}
diff --git a/src/net/lookup.go b/src/net/lookup.go
@@ -396,9 +396,6 @@ func (r *Resolver) LookupPort(ctx context.Context, network, service string) (por
 // contain DNS "CNAME" records, as long as host resolves to
 // address records.
 //
-// The returned canonical name is validated to be a properly
-// formatted presentation-format domain name.
-//
 // LookupCNAME uses context.Background internally; to specify the context, use
 // Resolver.LookupCNAME.
 func LookupCNAME(host string) (cname string, err error) {
@@ -415,18 +412,8 @@ func LookupCNAME(host string) (cname string, err error) {
 // LookupCNAME does not return an error if host does not
 // contain DNS "CNAME" records, as long as host resolves to
 // address records.
-//
-// The returned canonical name is validated to be a properly
-// formatted presentation-format domain name.
-func (r *Resolver) LookupCNAME(ctx context.Context, host string) (string, error) {
-	cname, err := r.lookupCNAME(ctx, host)
-	if err != nil {
-		return "", err
-	}
-	if !isDomainName(cname) {
-		return "", &DNSError{Err: "CNAME target is invalid", Name: host}
-	}
-	return cname, nil
+func (r *Resolver) LookupCNAME(ctx context.Context, host string) (cname string, err error) {
+	return r.lookupCNAME(ctx, host)
 }
 
 // LookupSRV tries to resolve an SRV query of the given service,
@@ -438,9 +425,6 @@ func (r *Resolver) LookupCNAME(ctx context.Context, host string) (string, error)
 // That is, it looks up _service._proto.name. To accommodate services
 // publishing SRV records under non-standard names, if both service
 // and proto are empty strings, LookupSRV looks up name directly.
-//
-// The returned service names are validated to be properly
-// formatted presentation-format domain names.
 func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err error) {
 	return DefaultResolver.lookupSRV(context.Background(), service, proto, name)
 }
@@ -454,88 +438,34 @@ func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err err
 // That is, it looks up _service._proto.name. To accommodate services
 // publishing SRV records under non-standard names, if both service
 // and proto are empty strings, LookupSRV looks up name directly.
-//
-// The returned service names are validated to be properly
-// formatted presentation-format domain names.
-func (r *Resolver) LookupSRV(ctx context.Context, service, proto, name string) (string, []*SRV, error) {
-	cname, addrs, err := r.lookupSRV(ctx, service, proto, name)
-	if err != nil {
-		return "", nil, err
-	}
-	if cname != "" && !isDomainName(cname) {
-		return "", nil, &DNSError{Err: "SRV header name is invalid", Name: name}
-	}
-	for _, addr := range addrs {
-		if addr == nil {
-			continue
-		}
-		if !isDomainName(addr.Target) {
-			return "", nil, &DNSError{Err: "SRV target is invalid", Name: name}
-		}
-	}
-	return cname, addrs, nil
+func (r *Resolver) LookupSRV(ctx context.Context, service, proto, name string) (cname string, addrs []*SRV, err error) {
+	return r.lookupSRV(ctx, service, proto, name)
 }
 
 // LookupMX returns the DNS MX records for the given domain name sorted by preference.
 //
-// The returned mail server names are validated to be properly
-// formatted presentation-format domain names.
-//
 // LookupMX uses context.Background internally; to specify the context, use
 // Resolver.LookupMX.
 func LookupMX(name string) ([]*MX, error) {
 	return DefaultResolver.lookupMX(context.Background(), name)
 }
 
 // LookupMX returns the DNS MX records for the given domain name sorted by preference.
-//
-// The returned mail server names are validated to be properly
-// formatted presentation-format domain names.
 func (r *Resolver) LookupMX(ctx context.Context, name string) ([]*MX, error) {
-	records, err := r.lookupMX(ctx, name)
-	if err != nil {
-		return nil, err
-	}
-	for _, mx := range records {
-		if mx == nil {
-			continue
-		}
-		if !isDomainName(mx.Host) {
-			return nil, &DNSError{Err: "MX target is invalid", Name: name}
-		}
-	}
-	return records, nil
+	return r.lookupMX(ctx, name)
 }
 
 // LookupNS returns the DNS NS records for the given domain name.
 //
-// The returned name server names are validated to be properly
-// formatted presentation-format domain names.
-//
 // LookupNS uses context.Background internally; to specify the context, use
 // Resolver.LookupNS.
 func LookupNS(name string) ([]*NS, error) {
 	return DefaultResolver.lookupNS(context.Background(), name)
 }
 
 // LookupNS returns the DNS NS records for the given domain name.
-//
-// The returned name server names are validated to be properly
-// formatted presentation-format domain names.
 func (r *Resolver) LookupNS(ctx context.Context, name string) ([]*NS, error) {
-	records, err := r.lookupNS(ctx, name)
-	if err != nil {
-		return nil, err
-	}
-	for _, ns := range records {
-		if ns == nil {
-			continue
-		}
-		if !isDomainName(ns.Host) {
-			return nil, &DNSError{Err: "NS target is invalid", Name: name}
-		}
-	}
-	return records, nil
+	return r.lookupNS(ctx, name)
 }
 
 // LookupTXT returns the DNS TXT records for the given domain name.
@@ -565,18 +495,6 @@ func LookupAddr(addr string) (names []string, err error) {
 
 // LookupAddr performs a reverse lookup for the given address, returning a list
 // of names mapping to that address.
-//
-// The returned names are validated to be properly
-// formatted presentation-format domain names.
-func (r *Resolver) LookupAddr(ctx context.Context, addr string) ([]string, error) {
-	names, err := r.lookupAddr(ctx, addr)
-	if err != nil {
-		return nil, err
-	}
-	for _, name := range names {
-		if !isDomainName(name) {
-			return nil, &DNSError{Err: "PTR target is invalid", Name: addr}
-		}
-	}
-	return names, nil
+func (r *Resolver) LookupAddr(ctx context.Context, addr string) (names []string, err error) {
+	return r.lookupAddr(ctx, addr)
 }
