Vendor keycard-go/derivationpath

vendor/github.com/status-im/keycard-go/derivationpath/decoder.go

@@ -0,0 +1,214 @@
+package derivationpath
+
+import (
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+)
+
+type StartingPoint int
+
+const (
+	tokenMaster    = 0x6D // char m
+	tokenSeparator = 0x2F // char /
+	tokenHardened  = 0x27 // char '
+	tokenDot       = 0x2E // char .
+
+	hardenedStart = 0x80000000 // 2^31
+)
+
+const (
+	StartingPointMaster StartingPoint = iota + 1
+	StartingPointCurrent
+	StartingPointParent
+)
+
+type parseFunc = func() error
+
+type decoder struct {
+	r                    *strings.Reader
+	f                    parseFunc
+	pos                  int
+	path                 []uint32
+	start                StartingPoint
+	currentToken         string
+	currentTokenHardened bool
+}
+
+func newDecoder(path string) *decoder {
+	d := &decoder{
+		r: strings.NewReader(path),
+	}
+
+	d.reset()
+
+	return d
+}
+
+func (d *decoder) reset() {
+	d.r.Seek(0, io.SeekStart)
+	d.pos = 0
+	d.start = StartingPointCurrent
+	d.f = d.parseStart
+	d.path = make([]uint32, 0)
+	d.resetCurrentToken()
+}
+
+func (d *decoder) resetCurrentToken() {
+	d.currentToken = ""
+	d.currentTokenHardened = false
+}
+
+func (d *decoder) parse() (StartingPoint, []uint32, error) {
+	for {
+		err := d.f()
+		if err != nil {
+			if err == io.EOF {
+				err = nil
+			} else {
+				err = fmt.Errorf("at position %d, %s", d.pos, err.Error())
+			}
+
+			return d.start, d.path, err
+		}
+	}
+
+	return d.start, d.path, nil
+}
+
+func (d *decoder) readByte() (byte, error) {
+	b, err := d.r.ReadByte()
+	if err != nil {
+		return b, err
+	}
+
+	d.pos++
+
+	return b, nil
+}
+
+func (d *decoder) unreadByte() error {
+	err := d.r.UnreadByte()
+	if err != nil {
+		return err
+	}
+
+	d.pos--
+
+	return nil
+}
+
+func (d *decoder) parseStart() error {
+	b, err := d.readByte()
+	if err != nil {
+		return err
+	}
+
+	if b == tokenMaster {
+		d.start = StartingPointMaster
+		d.f = d.parseSeparator
+		return nil
+	}
+
+	if b == tokenDot {
+		b2, err := d.readByte()
+		if err != nil {
+			return err
+		}
+
+		if b2 == tokenDot {
+			d.f = d.parseSeparator
+			d.start = StartingPointParent
+			return nil
+		}
+
+		d.f = d.parseSeparator
+		d.start = StartingPointCurrent
+		return d.unreadByte()
+	}
+
+	d.f = d.parseSegment
+
+	return d.unreadByte()
+}
+
+func (d *decoder) saveSegment() error {
+	if len(d.currentToken) > 0 {
+		i, err := strconv.ParseUint(d.currentToken, 10, 32)
+		if err != nil {
+			return err
+		}
+
+		if i >= hardenedStart {
+			d.pos -= len(d.currentToken) - 1
+			return fmt.Errorf("index must be lower than 2^31, got %d", i)
+		}
+
+		if d.currentTokenHardened {
+			i += hardenedStart
+		}
+
+		d.path = append(d.path, uint32(i))
+	}
+
+	d.f = d.parseSegment
+	d.resetCurrentToken()
+
+	return nil
+}
+
+func (d *decoder) parseSeparator() error {
+	b, err := d.readByte()
+	if err != nil {
+		return err
+	}
+
+	if b == tokenSeparator {
+		return d.saveSegment()
+	}
+
+	return fmt.Errorf("expected %s, got %s", string(tokenSeparator), string(b))
+}
+
+func (d *decoder) parseSegment() error {
+	b, err := d.readByte()
+	if err == io.EOF {
+		if len(d.currentToken) == 0 {
+			return fmt.Errorf("expected number, got EOF")
+		}
+
+		if newErr := d.saveSegment(); newErr != nil {
+			return newErr
+		}
+
+		return err
+	}
+
+	if err != nil {
+		return err
+	}
+
+	if len(d.currentToken) > 0 && b == tokenSeparator {
+		return d.saveSegment()
+	}
+
+	if len(d.currentToken) > 0 && b == tokenHardened {
+		d.currentTokenHardened = true
+		d.f = d.parseSeparator
+		return nil
+	}
+
+	if b < 0x30 || b > 0x39 {
+		return fmt.Errorf("expected number, got %s", string(b))
+	}
+
+	d.currentToken = fmt.Sprintf("%s%s", d.currentToken, string(b))
+
+	return nil
+}
+
+func Decode(str string) (StartingPoint, []uint32, error) {
+	d := newDecoder(str)
+	return d.parse()
+}