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tlv+hop: contain odd/even logic in payload parsing

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Tlv is used more widely in lnd than just for the onion payload. This
commit isolated the protocol-specific odd/even logic, so that tlv can be
used freely elsewhere. An example of this use is db serialization.
This commit is contained in:
Joost Jager
2019-11-10 12:06:49 +01:00
parent b222b6e625
commit 048971b40b
5 changed files with 66 additions and 136 deletions
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43
tlv/stream.go
View File

@@ -2,7 +2,6 @@ package tlv
import (
"errors"
"fmt"
"io"
"io/ioutil"
"math"
@@ -22,15 +21,6 @@ var ErrStreamNotCanonical = errors.New("tlv stream is not canonical")
// long to parse.
var ErrRecordTooLarge = errors.New("record is too large")
// ErrUnknownRequiredType is an error returned when decoding an unknown and even
// type from a Stream.
type ErrUnknownRequiredType Type
// Error returns a human-readable description of unknown required type.
func (t ErrUnknownRequiredType) Error() string {
return fmt.Sprintf("unknown required type: %d", t)
}
// Stream defines a TLV stream that can be used for encoding or decoding a set
// of TLV Records.
type Stream struct {
@@ -162,7 +152,6 @@ func (s *Stream) decode(r io.Reader, parsedTypes TypeSet) (TypeSet, error) {
var (
typ Type
min Type
firstFail *Type
recordIdx int
overflow bool
)
@@ -177,10 +166,7 @@ func (s *Stream) decode(r io.Reader, parsedTypes TypeSet) (TypeSet, error) {
// We'll silence an EOF when zero bytes remain, meaning the
// stream was cleanly encoded.
case err == io.EOF:
if firstFail == nil {
return parsedTypes, nil
}
return parsedTypes, ErrUnknownRequiredType(*firstFail)
return parsedTypes, nil
// Other unexpected errors.
case err != nil:
@@ -244,31 +230,6 @@ func (s *Stream) decode(r io.Reader, parsedTypes TypeSet) (TypeSet, error) {
return nil, err
}
// This record type is unknown to the stream, fail if the type
// is even meaning that we are required to understand it.
case typ%2 == 0:
// We'll fail immediately in the case that we aren't
// tracking the set of parsed types.
if parsedTypes == nil {
return nil, ErrUnknownRequiredType(typ)
}
// Otherwise, we'll track the first such failure and
// allow parsing to continue. If no other types of
// errors are encountered, the first failure will be
// returned as an ErrUnknownRequiredType so that the
// full set of included types can be returned.
if firstFail == nil {
failTyp := typ
firstFail = &failTyp
}
// With the failure type recorded, we'll simply discard
// the remainder of the record as if it were optional.
// The first failure will be returned after reaching the
// stopping condition.
fallthrough
// Otherwise, the record type is unknown and is odd, discard the
// number of bytes specified by length.
default:
@@ -289,7 +250,7 @@ func (s *Stream) decode(r io.Reader, parsedTypes TypeSet) (TypeSet, error) {
// Record the successfully decoded or ignored type if the
// caller provided an initialized TypeSet.
if parsedTypes != nil {
parsedTypes[typ] = struct{}{}
parsedTypes[typ] = ok
}
// Update our record index so that we can begin our next search