cybercyst/go
1
0
Fork 0
mirror of https://github.com/golang/go.git synced 2025-05-05 15:43:04 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

net: accept a valid IP address in LookupMX

Browse Source 
Fixes #56025

Change-Id: I202fdd0e11afeb22c5bc22d91fe4bfea8987e727
Reviewed-on: https://go-review.googlesource.com/c/go/+/651056
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Roland Shoemaker <roland@golang.org>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This commit is contained in:
Ian Lance Taylor 2025-02-20 12:12:35 -08:00 committed by Gopher Robot
parent dceee2e983
commit f77bba43aa
3 changed files with 82 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
doc/next/6-stdlib/99-minor/net/56025.md Normal file
View File

@ -0,0 +1,5 @@
[LookupMX] and [(*Resolver).LookupMX] now return DNS names that look
like valid IP address, as well as valid domain names.
Previously if a name server returned an IP address as a DNS name,
LookupMX would discard it, as required by the RFCs.
However, name servers in practice do sometimes return IP addresses.

72
src/net/dnsclient_unix_test.go
View File

@ -2028,6 +2028,50 @@ func TestCVE202133195(t *testing.T) {
MX: dnsmessage.MustNewName("good.golang.org."),
},
},
dnsmessage.Resource{
Header: dnsmessage.ResourceHeader{
Name: dnsmessage.MustNewName("127.0.0.1."),
Type: dnsmessage.TypeMX,
Class: dnsmessage.ClassINET,
Length: 4,
},
Body: &dnsmessage.MXResource{
MX: dnsmessage.MustNewName("127.0.0.1."),
},
},
dnsmessage.Resource{
Header: dnsmessage.ResourceHeader{
Name: dnsmessage.MustNewName("1.2.3.4.5."),
Type: dnsmessage.TypeMX,
Class: dnsmessage.ClassINET,
Length: 4,
},
Body: &dnsmessage.MXResource{
MX: dnsmessage.MustNewName("1.2.3.4.5."),
},
},
dnsmessage.Resource{
Header: dnsmessage.ResourceHeader{
Name: dnsmessage.MustNewName("2001:4860:0:2001::68."),
Type: dnsmessage.TypeMX,
Class: dnsmessage.ClassINET,
Length: 4,
},
Body: &dnsmessage.MXResource{
MX: dnsmessage.MustNewName("2001:4860:0:2001::68."),
},
},
dnsmessage.Resource{
Header: dnsmessage.ResourceHeader{
Name: dnsmessage.MustNewName("2001:4860:0:2001::68%zone."),
Type: dnsmessage.TypeMX,
Class: dnsmessage.ClassINET,
Length: 4,
},
Body: &dnsmessage.MXResource{
MX: dnsmessage.MustNewName("2001:4860:0:2001::68%zone."),
},
},
)
case dnsmessage.TypeNS:
r.Answers = append(r.Answers,
@ -2152,25 +2196,37 @@ func TestCVE202133195(t *testing.T) {
{
name: "MX",
f: func(t *testing.T) {
expected := []*MX{
{
Host: "good.golang.org.",
},
expected := []string{
"127.0.0.1.",
"2001:4860:0:2001::68.",
"good.golang.org.",
}
expectedErr := &DNSError{Err: errMalformedDNSRecordsDetail, Name: "golang.org"}
records, err := r.LookupMX(context.Background(), "golang.org")
if err.Error() != expectedErr.Error() {
t.Fatalf("unexpected error: %s", err)
}
if !reflect.DeepEqual(records, expected) {
t.Error("Unexpected record set")
hosts := func(records []*MX) []string {
var got []string
for _, mx := range records {
got = append(got, mx.Host)
}
slices.Sort(got)
return got
}
got := hosts(records)
if !slices.Equal(got, expected) {
t.Errorf("Unexpected record set: got %v, want %v", got, expected)
}
records, err = LookupMX("golang.org")
if err.Error() != expectedErr.Error() {
t.Fatalf("unexpected error: %s", err)
}
if !reflect.DeepEqual(records, expected) {
t.Error("Unexpected record set")
got = hosts(records)
if !slices.Equal(got, expected) {
t.Errorf("Unexpected record set: got %v, want %v", got, expected)
}
},
},

20
src/net/lookup.go
View File

@ -9,6 +9,7 @@ import (
"errors"
"internal/nettrace"
"internal/singleflight"
"internal/stringslite"
"net/netip"
"sync"
@ -535,9 +536,9 @@ func (r *Resolver) LookupSRV(ctx context.Context, service, proto, name string) (
// 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. If the response contains
// invalid names, those records are filtered out and an error
// will be returned alongside the remaining results, if any.
// formatted presentation-format domain names, or numeric IP addresses.
// If the response contains invalid names, those records are filtered out
// and an error will be returned alongside the remaining results, if any.
//
// LookupMX uses [context.Background] internally; to specify the context, use
// [Resolver.LookupMX].
@ -548,9 +549,9 @@ func LookupMX(name string) ([]*MX, error) {
// 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. If the response contains
// invalid names, those records are filtered out and an error
// will be returned alongside the remaining results, if any.
// formatted presentation-format domain names, or numeric IP addresses.
// If the response contains invalid names, those records are filtered out
// and an error will be returned alongside the remaining results, if any.
func (r *Resolver) LookupMX(ctx context.Context, name string) ([]*MX, error) {
records, err := r.lookupMX(ctx, name)
if err != nil {
@ -562,7 +563,12 @@ func (r *Resolver) LookupMX(ctx context.Context, name string) ([]*MX, error) {
continue
}
if !isDomainName(mx.Host) {
continue
// Check for IP address. In practice we observe
// these with a trailing dot, so strip that.
ip, err := netip.ParseAddr(stringslite.TrimSuffix(mx.Host, "."))
if err != nil || ip.Zone() != "" {
continue
}
}
filteredMX = append(filteredMX, mx)
}