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dns/dnsmessage: allow name compression for SRV resource parsing #199

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dns/dnsmessage: allow name compression for SRV resource parsing #199

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c621db3
dns/dnsmessage: allow name compression for SRV
mateusz834 Nov 3, 2023
88d2e06
remove unpackCompressed method
mateusz834 Nov 7, 2023
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10 changes: 1 addition & 9 deletions dns/dnsmessage/message.go
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Original file line number Diff line number Diff line change
Expand Up @@ -273,7 +273,6 @@ var (
errTooManyAdditionals = errors.New("too many Additionals to pack (>65535)")
errNonCanonicalName = errors.New("name is not in canonical format (it must end with a .)")
errStringTooLong = errors.New("character string exceeds maximum length (255)")
errCompressedSRV = errors.New("compressed name in SRV resource data")
)

// Internal constants.
Expand Down Expand Up @@ -2028,10 +2027,6 @@ func (n *Name) pack(msg []byte, compression map[string]uint16, compressionOff in

// unpack unpacks a domain name.
func (n *Name) unpack(msg []byte, off int) (int, error) {
return n.unpackCompressed(msg, off, true /* allowCompression */)
}

func (n *Name) unpackCompressed(msg []byte, off int, allowCompression bool) (int, error) {
// currOff is the current working offset.
currOff := off

Expand Down Expand Up @@ -2076,9 +2071,6 @@ Loop:
name = append(name, '.')
currOff = endOff
case 0xC0: // Pointer
if !allowCompression {
return off, errCompressedSRV
}
if currOff >= len(msg) {
return off, errInvalidPtr
}
Expand Down Expand Up @@ -2549,7 +2541,7 @@ func unpackSRVResource(msg []byte, off int) (SRVResource, error) {
return SRVResource{}, &nestedError{"Port", err}
}
var target Name
if _, err := target.unpackCompressed(msg, off, false /* allowCompression */); err != nil {
if _, err := target.unpack(msg, off); err != nil {
return SRVResource{}, &nestedError{"Target", err}
}
return SRVResource{priority, weight, port, target}, nil
Expand Down
22 changes: 0 additions & 22 deletions dns/dnsmessage/message_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -303,28 +303,6 @@ func TestNameUnpackTooLongName(t *testing.T) {
}
}

func TestIncompressibleName(t *testing.T) {
name := MustNewName("example.com.")
compression := map[string]uint16{}
buf, err := name.pack(make([]byte, 0, 100), compression, 0)
if err != nil {
t.Fatal("first Name.pack() =", err)
}
buf, err = name.pack(buf, compression, 0)
if err != nil {
t.Fatal("second Name.pack() =", err)
}
var n1 Name
off, err := n1.unpackCompressed(buf, 0, false /* allowCompression */)
if err != nil {
t.Fatal("unpacking incompressible name without pointers failed:", err)
}
var n2 Name
if _, err := n2.unpackCompressed(buf, off, false /* allowCompression */); err != errCompressedSRV {
t.Errorf("unpacking compressed incompressible name with pointers: got %v, want = %v", err, errCompressedSRV)
}
}

func checkErrorPrefix(err error, prefix string) bool {
e, ok := err.(*nestedError)
return ok && e.s == prefix
Expand Down