diff options
| -rw-r--r-- | rfc1035label/label.go | 54 | ||||
| -rw-r--r-- | rfc1035label/label_test.go | 118 |
2 files changed, 127 insertions, 45 deletions
diff --git a/rfc1035label/label.go b/rfc1035label/label.go index c63b4af..26d8a49 100644 --- a/rfc1035label/label.go +++ b/rfc1035label/label.go @@ -1,39 +1,61 @@ package rfc1035label import ( - "fmt" + "errors" "strings" ) -// This implements the compression from RFC 1035, section 4.1.4 -// https://tools.ietf.org/html/rfc1035 +// This implements RFC 1035 labels, including compression. +// https://tools.ietf.org/html/rfc1035#section-4.1.4 // LabelsFromBytes decodes a serialized stream and returns a list of labels func LabelsFromBytes(buf []byte) ([]string, error) { var ( - pos = 0 - domains = make([]string, 0) - label = "" + pos, oldPos int + labels = make([]string, 0) + label string + handlingPointer bool ) + for { if pos >= len(buf) { - return domains, nil + break } length := int(buf[pos]) pos++ + var chunk string if length == 0 { - domains = append(domains, label) + labels = append(labels, label) label = "" + if handlingPointer { + pos = oldPos + handlingPointer = false + } + } else if length&0xc0 == 0xc0 { + // compression pointer + if handlingPointer { + return nil, errors.New("rfc1035label: cannot handle nested pointers") + } + handlingPointer = true + if pos+1 > len(buf) { + return nil, errors.New("rfc1035label: pointer buffer too short") + } + off := int(buf[pos-1]&^0xc0)<<8 + int(buf[pos]) + oldPos = pos + 1 + pos = off + } else { + if pos+length > len(buf) { + return nil, errors.New("rfc1035label: buffer too short") + } + chunk = string(buf[pos : pos+length]) + if label != "" { + label += "." + } + label += chunk + pos += length } - if len(buf)-pos < length { - return nil, fmt.Errorf("DomainNamesFromBytes: invalid short label length") - } - if label != "" { - label += "." - } - label += string(buf[pos : pos+length]) - pos += length } + return labels, nil } // LabelToBytes encodes a label and returns a serialized stream of bytes diff --git a/rfc1035label/label_test.go b/rfc1035label/label_test.go index f91110b..3a69f2b 100644 --- a/rfc1035label/label_test.go +++ b/rfc1035label/label_test.go @@ -1,8 +1,9 @@ package rfc1035label import ( - "bytes" "testing" + + "github.com/stretchr/testify/require" ) func TestLabelsFromBytes(t *testing.T) { @@ -11,38 +12,27 @@ func TestLabelsFromBytes(t *testing.T) { 0x2, 'i', 't', 0x0, }) - if err != nil { - t.Fatal(err) - } - if len(labels) != 1 { - t.Fatalf("Invalid labels length. Expected: 1, got: %v", len(labels)) - } - if labels[0] != "slackware.it" { - t.Fatalf("Invalid label. Expected: %v, got: %v'", "slackware.it", labels[0]) - } + require.NoError(t, err) + require.Equal(t, 1, len(labels)) + require.Equal(t, "slackware.it", labels[0]) } func TestLabelsFromBytesZeroLength(t *testing.T) { labels, err := LabelsFromBytes([]byte{}) - if err != nil { - t.Fatal(err) - } - if len(labels) != 0 { - t.Fatalf("Invalid labels length. Expected: 0, got: %v", len(labels)) - } + require.NoError(t, err) + require.Equal(t, 0, len(labels)) } func TestLabelsFromBytesInvalidLength(t *testing.T) { + labels, err := LabelsFromBytes([]byte{0x5, 0xaa, 0xbb}) // short length + require.Error(t, err) + require.Equal(t, 0, len(labels)) +} + +func TestLabelsFromBytesInvalidLengthOffByOne(t *testing.T) { labels, err := LabelsFromBytes([]byte{0x3, 0xaa, 0xbb}) // short length - if err == nil { - t.Fatal("Expected error, got nil") - } - if len(labels) != 0 { - t.Fatalf("Invalid labels length. Expected: 0, got: %v", len(labels)) - } - if labels != nil { - t.Fatalf("Invalid label. Expected nil, got %v", labels) - } + require.Error(t, err) + require.Equal(t, 0, len(labels)) } func TestLabelToBytes(t *testing.T) { @@ -52,15 +42,85 @@ func TestLabelToBytes(t *testing.T) { 0x2, 'i', 't', 0x0, } - if !bytes.Equal(encodedLabel, expected) { - t.Fatalf("Invalid label. Expected: %v, got: %v", expected, encodedLabel) + require.Equal(t, expected, encodedLabel) +} + +func TestLabelsToBytes(t *testing.T) { + expected := []byte{ + 9, 's', 'l', 'a', 'c', 'k', 'w', 'a', 'r', 'e', + 2, 'i', 't', + 0, + 9, 'i', 'n', 's', 'o', 'm', 'n', 'i', 'a', 'c', + 9, 's', 'l', 'a', 'c', 'k', 'w', 'a', 'r', 'e', + 2, 'i', 't', + 0, } + encodedLabels := LabelsToBytes([]string{"slackware.it", "insomniac.slackware.it"}) + require.Equal(t, expected, encodedLabels) } func TestLabelToBytesZeroLength(t *testing.T) { encodedLabel := LabelToBytes("") expected := []byte{0} - if !bytes.Equal(encodedLabel, expected) { - t.Fatalf("Invalid label. Expected: %v, got: %v", expected, encodedLabel) + require.Equal(t, expected, encodedLabel) +} + +func TestCompressedLabel(t *testing.T) { + data := []byte{ + // slackware.it + 9, 's', 'l', 'a', 'c', 'k', 'w', 'a', 'r', 'e', + 2, 'i', 't', + 0, + // insomniac.slackware.it + 9, 'i', 'n', 's', 'o', 'm', 'n', 'i', 'a', 'c', + 192, 0, + // mail.systemboot.org + 4, 'm', 'a', 'i', 'l', + 10, 's', 'y', 's', 't', 'e', 'm', 'b', 'o', 'o', 't', + 3, 'o', 'r', 'g', + 0, + // systemboot.org + 192, 31, + } + expected := []string{ + "slackware.it", + "insomniac.slackware.it", + "mail.systemboot.org", + "systemboot.org", + } + + labels, err := LabelsFromBytes(data) + require.NoError(t, err) + require.Equal(t, expected, labels) +} + +func TestShortCompressedLabel(t *testing.T) { + data := []byte{ + // slackware.it + 9, 's', 'l', 'a', 'c', 'k', 'w', 'a', 'r', 'e', + 2, 'i', 't', + 0, + // insomniac.slackware.it + 9, 'i', 'n', 's', 'o', 'm', 'n', 'i', 'a', 'c', + 192, + } + + _, err := LabelsFromBytes(data) + require.Error(t, err) +} + +func TestNestedCompressedLabel(t *testing.T) { + data := []byte{ + // it + 3, 'i', 't', + 0, + // slackware.it + 9, 's', 'l', 'a', 'c', 'k', 'w', 'a', 'r', 'e', + 192, 0, + // insomniac.slackware.it + 9, 'i', 'n', 's', 'o', 'm', 'n', 'i', 'a', 'c', + 192, 5, } + _, err := LabelsFromBytes(data) + require.Error(t, err) } |