Add fuzzing test and fix decoding slashes in text

decoder.go

@@ -35,6 +35,7 @@ type decoder struct {
 	read                byte
 	write               byte
 	top                 byte
+	lastStartElement    bool
 }
 
 // NewDecoder creates a new Decoder.
@@ -130,22 +131,32 @@ func (thiz *decoder) NextToken(t *Token) error {
 			// That's fine. We just did not consume the end token
 			// because there could have been an implicit
 			// "/>" close at the end of the start element.
+			thiz.lastStartElement = false
 		case '/':
-			// Immediately closing last openend StartElement.
-			// This will generate an EndElement with the same
-			// name that we used in the previous StartElement.
-			_, err = thiz.discard(1)
-			if err != nil {
+			if thiz.lastStartElement {
+				// Immediately closing last openend StartElement.
+				// This will generate an EndElement with the same
+				// name that we used in the previous StartElement.
+				_, err = thiz.discard(1)
+				if err != nil {
+					return err
+				}
+				thiz.lastStartElement = false
+				return thiz.decodeEndElement(t, thiz.lastOpen)
+			}
+			thiz.unreadByte()
+			cntn, err := thiz.decodeText(t)
+			if err != nil || !cntn {
 				return err
 			}
-			return thiz.decodeEndElement(t, thiz.lastOpen)
 		case '<':
 			b, err = thiz.readByte()
 			if err != nil {
 				return err
 			}
 			switch b {
 			case '?':
+				thiz.lastStartElement = false
 				err = thiz.decodeProcInst(t)
 				thiz.unreadByte()
 				return err
@@ -162,6 +173,7 @@ func (thiz *decoder) NextToken(t *Token) error {
 						return err
 					}
 				case '[':
+					thiz.lastStartElement = false
 					return thiz.readCDATA()
 				default:
 					return errors.New("invalid XML: comment or CDATA expected")
@@ -172,11 +184,14 @@ func (thiz *decoder) NextToken(t *Token) error {
 				if err != nil {
 					return err
 				}
+				thiz.lastStartElement = false
 				return thiz.decodeEndElement(t, name)
 			default:
+				thiz.lastStartElement = true
 				return thiz.decodeStartElement(t)
 			}
 		default:
+			thiz.lastStartElement = false
 			thiz.unreadByte()
 			cntn, err := thiz.decodeText(t)
 			if err != nil || !cntn {

fuzzing_test.go

@@ -0,0 +1,119 @@
+package gosaxml_test
+
+import (
+	"bytes"
+	"github.com/HBTGmbH/gosaxml"
+	"github.com/stretchr/testify/assert"
+	"io"
+	"math/rand"
+	"testing"
+)
+
+var startNameRunes = []rune(":-_abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+var restNameRunes = []rune("0123456789-_abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+var stringRunes = []rune("/:+*#.!§$%&/[]=?`´'0123456789-_abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+var textRunes = []rune("\"/:+*#'.!§$%&[]=?`´'0123456789-_abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+
+func randName(r *rand.Rand) string {
+	c := 1 + r.Intn(10)
+	b := make([]rune, c)
+	b[0] = startNameRunes[r.Intn(len(startNameRunes))]
+	for i := 1; i < c; i++ {
+		b[i] = restNameRunes[r.Intn(len(restNameRunes))]
+	}
+	return string(b)
+}
+
+func randText(r *rand.Rand) string {
+	c := 1 + r.Intn(255)
+	b := make([]rune, c)
+	for i := 0; i < c; i++ {
+		b[i] = textRunes[r.Intn(len(textRunes))]
+	}
+	return string(b)
+}
+
+func randString(r *rand.Rand) string {
+	c := r.Intn(30)
+	b := make([]rune, c)
+	for i := 0; i < c; i++ {
+		b[i] = stringRunes[r.Intn(len(stringRunes))]
+	}
+	return string(b)
+}
+
+func buildElement(i int, b *bytes.Buffer, r *rand.Rand, lastOpen bool) bool {
+	switch i {
+	case 0:
+		if lastOpen {
+			b.WriteString(">")
+		}
+		name := randName(r)
+		b.WriteString("<")
+		b.WriteString(name)
+		numAttrs := r.Intn(10)
+		for j := 0; j < numAttrs; j++ {
+			b.WriteString(" ")
+			buildAttribute(b, r)
+		}
+		ended := buildElement(r.Intn(2), b, r, true)
+		if !ended {
+			b.WriteString("</")
+			b.WriteString(name)
+			b.WriteString(">")
+		}
+		return false
+	case 1:
+		if lastOpen {
+			b.WriteString(">")
+		}
+		b.WriteString(randText(r))
+		return false
+	default:
+		b.WriteString("/>")
+		return true
+	}
+}
+
+func buildAttribute(b *bytes.Buffer, r *rand.Rand) {
+	name := randName(r)
+	value := randString(r)
+	randName(r)
+	b.WriteString(name)
+	b.WriteString("=\"")
+	b.WriteString(value)
+	b.WriteString("\"")
+}
+
+func TestFuzz(t *testing.T) {
+	// given
+	s1 := rand.NewSource(123456789)
+	r := rand.New(s1)
+	n := 100000
+
+	for i := 0; i < n; i++ {
+		b := &bytes.Buffer{}
+		buildElement(0, b, r, false)
+		xml := b.String()
+		reader := bytes.NewReader(b.Bytes())
+		dec := gosaxml.NewDecoder(reader)
+		w := &bytes.Buffer{}
+		enc := gosaxml.NewEncoder(w, gosaxml.NewNamespaceModifier())
+		var tk gosaxml.Token
+
+		// when
+		for {
+			err := dec.NextToken(&tk)
+			if err == io.EOF {
+				break
+			}
+			assert.Nil(t, err)
+			err = enc.EncodeToken(&tk)
+			assert.Nil(t, err)
+		}
+		assert.Nil(t, enc.Flush())
+
+		// then
+		assert.Equal(t, xml, w.String())
+	}
+}