ident: implement remote-part validation
This is mostly equivalent to email without IP addresses. Signed-off-by: Yonah <contrib@gensokyo.uk>
This commit is contained in:
@@ -88,6 +88,42 @@ func TestErrors(t *testing.T) {
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Data: make([]byte, 1<<10),
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Want: ident.EncodedSizeSystem,
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}, "got 1024 bytes for a 32-byte identifier"},
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{"InvalidLabelLDH start", &ident.InvalidLabelError{
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Data: []byte{'-'},
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Label: 0xbad,
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Index: 0,
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Reason: ident.InvalidLabelLDH,
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}, "label 2989 starts with '-'"},
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{"InvalidLabelLDH end", &ident.InvalidLabelError{
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Data: []byte{0, '-'},
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Label: 0xbad,
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Index: 1,
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Reason: ident.InvalidLabelLDH,
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}, "label 2989 ends with '-'"},
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{"InvalidLabelLDH", &ident.InvalidLabelError{
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Data: []byte{0},
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Label: 0xbad,
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Index: 0,
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Reason: ident.InvalidLabelLDH,
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}, `label 2989 contains invalid byte '\x00' at index 0`},
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{"InvalidLabelShort", &ident.InvalidLabelError{
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Label: 0xf00d,
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Reason: ident.InvalidLabelShort,
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}, "label 61453 is empty"},
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{"InvalidLabelLong", &ident.InvalidLabelError{
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Label: 0xf00d,
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Reason: ident.InvalidLabelLong,
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}, "label 61453 is longer than 63 bytes"},
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{"InvalidLabelError", &ident.InvalidLabelError{
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Label: 0xcafe,
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Reason: 0xbadf00d,
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}, "invalid label 51966 at byte 0"},
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}
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for _, tc := range testCases {
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t.Run(tc.name, func(t *testing.T) {
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153
ident/remote.go
Normal file
153
ident/remote.go
Normal file
@@ -0,0 +1,153 @@
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package ident
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import (
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"bytes"
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"errors"
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"fmt"
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"strconv"
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)
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// ldh are bytes that may appear in a DNS label of Remote.
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var ldh = [1 << 8]bool{
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'-': true, // special: must not be the first or last byte
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'0': true, '1': true, '2': true, '3': true, '4': true, '5': true, '6': true,
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'7': true, '8': true, '9': true,
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'A': true, 'B': true, 'C': true, 'D': true, 'E': true, 'F': true, 'G': true,
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'H': true, 'I': true, 'J': true, 'K': true, 'L': true, 'M': true, 'N': true,
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'O': true, 'P': true, 'Q': true, 'R': true, 'S': true, 'T': true, 'U': true,
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'V': true, 'W': true, 'X': true, 'Y': true, 'Z': true,
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'a': true, 'b': true, 'c': true, 'd': true, 'e': true, 'f': true, 'g': true,
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'h': true, 'i': true, 'j': true, 'k': true, 'l': true, 'm': true, 'n': true,
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'o': true, 'p': true, 'q': true, 'r': true, 's': true, 't': true, 'u': true,
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'v': true, 'w': true, 'x': true, 'y': true, 'z': true,
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}
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const (
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// RemoteMax is the maximum permissible size of [Remote].
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RemoteMax = 1<<8 - 1
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// LabelSeparator separates labels in a [Remote].
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LabelSeparator = '.'
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// LabelMax is the maximum permissible size of a label in [Remote].
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LabelMax = 1<<6 - 1
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)
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// Remote represents the remote part of [F].
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//
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// A remote must contain one or more non-empty labels, separated by
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// [LabelSeparator]. Each label must be no more than [LabelMax] bytes long, and
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// contain only bytes permitted by the "LDH rule" described in
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// [Section 2 of RFC 3696]. A remote must, in total, be no more than [RemoteMax]
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// bytes long.
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//
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// [Section 2 of RFC 3696]: https://www.rfc-editor.org/rfc/rfc3696#section-2
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type Remote struct {
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Data [RemoteMax + 1]byte
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Len uint8
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}
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// Encode appends the underlying string to dst and returns the extended buffer.
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func (r *Remote) Encode(dst []byte) []byte {
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return append(dst, r.Data[:r.Len]...)
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}
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// String returns a copy of the underlying string.
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func (r *Remote) String() string { return string(r.Data[:r.Len]) }
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// MarshalText returns the result of Encode.
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func (r *Remote) MarshalText() (data []byte, err error) {
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return r.Encode(nil), nil
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}
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var (
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// ErrShortRemote is returned validating an empty remote.
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ErrShortRemote = errors.New("missing remote part")
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// ErrLongRemote is returned validating a remote longer than [RemoteMax].
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ErrLongRemote = errors.New("got more than 255 bytes of remote")
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)
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const (
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// InvalidLabelLDH denotes an [InvalidLabelError] describing an invalid
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// label containing bytes not permitted by the LDH rule.
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InvalidLabelLDH = iota
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// InvalidLabelShort denotes an [InvalidLabelError] describing an empty label.
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InvalidLabelShort
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// InvalidLabelLong denotes an [InvalidLabelError] describing a label
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// exceeding its maximum length of [LabelMax].
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InvalidLabelLong
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)
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// An InvalidLabelError describes a rejected DNS label part of a [Remote].
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type InvalidLabelError struct {
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Data []byte
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Label int
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Index int
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Reason int
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}
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func (e *InvalidLabelError) Error() string {
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s := "label " + strconv.Itoa(e.Label) + " "
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switch e.Reason {
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case InvalidLabelLDH:
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if e.Data[e.Index] == '-' {
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if e.Index == 0 {
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s += "starts"
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} else {
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s += "ends"
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}
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s += " with '-'"
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break
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}
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s += fmt.Sprintf(
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"contains invalid byte %q at index %d",
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e.Data[e.Index], e.Index,
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)
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case InvalidLabelShort:
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s += "is empty"
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case InvalidLabelLong:
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s += "is longer than 63 bytes"
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default:
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return "invalid label " + strconv.Itoa(e.Label) +
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" at byte " + strconv.Itoa(e.Index)
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}
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return s
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}
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// UnmarshalText validates and copies data to r.
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func (r *Remote) UnmarshalText(data []byte) error {
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if len(data) == 0 {
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return ErrShortRemote
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}
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r.Len = uint8(len(data))
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if copy(r.Data[:], data) == len(r.Data) {
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return ErrLongRemote
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}
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for i, label := range bytes.Split(r.Data[:r.Len], []byte{LabelSeparator}) {
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if len(label) == 0 {
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return &InvalidLabelError{label, i, -1, InvalidLabelShort}
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} else if len(label) > LabelMax {
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return &InvalidLabelError{label, i, LabelMax, InvalidLabelLong}
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}
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if label[0] == '-' {
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return &InvalidLabelError{label, i, 0, InvalidLabelLDH}
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} else if label[len(label)-1] == '-' {
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return &InvalidLabelError{label, i, len(label) - 1, InvalidLabelLDH}
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}
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for j, b := range label {
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if !ldh[b] {
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return &InvalidLabelError{label, i, j, InvalidLabelLDH}
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}
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}
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}
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return nil
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}
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83
ident/remote_test.go
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83
ident/remote_test.go
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@@ -0,0 +1,83 @@
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package ident_test
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import (
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"bytes"
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"strings"
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"testing"
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"git.gensokyo.uk/cofront/cof-spec/ident"
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)
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// mustNewRemote validates remote and returns its corresponding [ident.Remote].
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// If remote is invalid, mustNewRemote panics.
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func mustNewRemote(remote string) (r ident.Remote) {
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if err := r.UnmarshalText([]byte(remote)); err != nil {
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panic(err)
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}
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return
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}
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func TestRemote(t *testing.T) {
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t.Parallel()
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testCases := []struct {
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name string
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remote string
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err error
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}{
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{"short", "", ident.ErrShortRemote},
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{"long", strings.Repeat("\x00", 256), ident.ErrLongRemote},
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{"short label", "test.label.short..empty", &ident.InvalidLabelError{
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Data: []byte{},
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Label: 3,
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Index: -1,
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Reason: ident.InvalidLabelShort,
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}},
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{"long label", "test.label.long." + strings.Repeat("\x00", 64), &ident.InvalidLabelError{
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Data: bytes.Repeat([]byte{0}, 64),
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Label: 3,
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Index: 63,
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Reason: ident.InvalidLabelLong,
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}},
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{"ldh prefix", "test.prefix.-invalid-", &ident.InvalidLabelError{
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Data: []byte("-invalid-"),
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Label: 2,
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Index: 0,
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Reason: ident.InvalidLabelLDH,
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}},
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{"ldh suffix", "test.suffix.invalid--", &ident.InvalidLabelError{
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Data: []byte("invalid--"),
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Label: 2,
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Index: 8,
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Reason: ident.InvalidLabelLDH,
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}},
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{"ldh", "test.invalid:byte", &ident.InvalidLabelError{
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Data: []byte("invalid:byte"),
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Label: 1,
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Index: 7,
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Reason: ident.InvalidLabelLDH,
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}},
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{"simple", "localhost", nil},
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{"valid", "gensokyo.uk", nil},
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{"full", "ABCDEFGHIJKLMNOPQRSTUVWXYZ." +
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"abcdefghijklmnopqrstuvwxyz." +
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"0123456789-9876543210", nil},
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}
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rtc := make(rTestCases[ident.Remote, *ident.Remote], len(testCases))
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for i, tc := range testCases {
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rtc[i].name = tc.name
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if tc.err == nil {
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rtc[i].ident = mustNewRemote(tc.remote)
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}
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rtc[i].want = []byte(tc.remote)
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rtc[i].err = tc.err
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}
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rtc.run(t)
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}
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