fix Sign/Verify to take byte slices not strings

examples/xmldsig.go

@@ -33,16 +33,16 @@ func main() {
 	buf, err := ioutil.ReadAll(os.Stdin)
 
 	if *doSign {
-		signedBuf, err := xmldsig.Sign(key, string(buf))
+		signedBuf, err := xmldsig.Sign(key, buf)
 		if err != nil {
 			fmt.Printf("%s\n", err)
 			os.Exit(1)
 		}
-		fmt.Print(signedBuf)
+		os.Stdout.Write(signedBuf)
 	}
 
 	if *doVerify {
-		err := xmldsig.Verify(key, string(buf))
+		err := xmldsig.Verify(key, buf)
 		if err == xmldsig.ErrVerificationFailed {
 			fmt.Println("signature is not correct")
 			os.Exit(1)

xmldsig/xmldsig.go

@@ -59,8 +59,9 @@ func closeContext(ctx *C.xmlSecDSigCtx) {
 	C.xmlSecDSigCtxDestroy(ctx)
 }
 
-func newDoc(s string) (*C.xmlDoc, error) {
-	ctx := C.xmlCreateMemoryParserCtxt(C.CString(s), C.int(len(s)))
+func newDoc(buf []byte) (*C.xmlDoc, error) {
+	ctx := C.xmlCreateMemoryParserCtxt((*C.char)(unsafe.Pointer(&buf[0])),
+		C.int(len(buf)))
 	if ctx == nil {
 		return nil, errors.New("error creating parser")
 	}
@@ -80,13 +81,16 @@ func newDoc(s string) (*C.xmlDoc, error) {
 	return doc, nil
 }
 
-func dumpDoc(doc *C.xmlDoc) string {
+func dumpDoc(doc *C.xmlDoc) []byte {
 	var buffer *C.xmlChar
 	var bufferSize C.int
 	C.xmlDocDumpMemory(doc, &buffer, &bufferSize)
 	rv := C.GoStringN((*C.char)(unsafe.Pointer(buffer)), bufferSize)
 	C.MY_xmlFree(unsafe.Pointer(buffer))
-	return rv
+
+	// TODO(ross): this is totally nasty un-idiomatic, but I'm
+	// tired of googling how to copy a []byte from a char*
+	return []byte(rv)
 }
 
 func closeDoc(doc *C.xmlDoc) {
@@ -97,31 +101,31 @@ func closeDoc(doc *C.xmlDoc) {
 // the XML-DSIG standard. docStr is a template document meaning
 // that it contains a `Signature` element in the
 // http://www.w3.org/2000/09/xmldsig# namespace.
-func Sign(key []byte, docStr string) (string, error) {
+func Sign(key []byte, doc []byte) ([]byte, error) {
 	ctx, err := newContext(key)
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 	defer closeContext(ctx)
 
-	doc, err := newDoc(docStr)
+	parsedDoc, err := newDoc(doc)
 	if err != nil {
-		return "", err
+		return nil, err
 	}
-	defer closeDoc(doc)
+	defer closeDoc(parsedDoc)
 
-	node := C.xmlSecFindNode(C.xmlDocGetRootElement(doc),
+	node := C.xmlSecFindNode(C.xmlDocGetRootElement(parsedDoc),
 		(*C.xmlChar)(unsafe.Pointer(&C.xmlSecNodeSignature)),
 		(*C.xmlChar)(unsafe.Pointer(&C.xmlSecDSigNs)))
 	if node == nil {
-		return "", errors.New("cannot find start node")
+		return nil, errors.New("cannot find start node")
 	}
 
 	if rv := C.xmlSecDSigCtxSign(ctx, node); rv < 0 {
-		return "", errors.New("failed to sign")
+		return nil, errors.New("failed to sign")
 	}
 
-	return dumpDoc(doc), nil
+	return dumpDoc(parsedDoc), nil
 }
 
 // ErrVerificationFailed is returned from Verify when the signature is incorrect
@@ -137,20 +141,20 @@ const (
 // to the XML-DSIG specification. publicKey is the public part of
 // the key used to sign docStr. If the signature is not correct,
 // this function returns ErrVarificationFailed.
-func Verify(publicKey []byte, docStr string) error {
+func Verify(publicKey []byte, doc []byte) error {
 	ctx, err := newContext(publicKey)
 	if err != nil {
 		return err
 	}
 	defer closeContext(ctx)
 
-	doc, err := newDoc(docStr)
+	parsedDoc, err := newDoc(doc)
 	if err != nil {
 		return err
 	}
-	defer closeDoc(doc)
+	defer closeDoc(parsedDoc)
 
-	node := C.xmlSecFindNode(C.xmlDocGetRootElement(doc),
+	node := C.xmlSecFindNode(C.xmlDocGetRootElement(parsedDoc),
 		(*C.xmlChar)(unsafe.Pointer(&C.xmlSecNodeSignature)),
 		(*C.xmlChar)(unsafe.Pointer(&C.xmlSecDSigNs)))
 	if node == nil {

xmldsig/xmldsig_test.go

@@ -23,7 +23,7 @@ Un0PLcemAzPi8ADJlbMDG/IDXNbSej0Y4tw9Cdho1Q38XLZJi0RNdNvQJD1fWu3x
 9+QU/vJr7lMLzdoy
 -----END PRIVATE KEY-----`)
 
-	docStr := `<?xml version="1.0" encoding="UTF-8"?>
+	docStr := []byte(`<?xml version="1.0" encoding="UTF-8"?>
 <!--
 XML Security Library example: Simple signature template file for sign1 example.
 -->
@@ -58,18 +58,20 @@ XML Security Library example: Simple signature template file for sign1 example.
 		return
 	}
 
-	if actualSignedString != expectedSignedString {
-		t.Errorf("signed: expected %q, got `%q`", expectedSignedString, actualSignedString)
+	if string(actualSignedString) != expectedSignedString {
+		t.Errorf("signed: expected %q, got `%q`", expectedSignedString, string(actualSignedString))
+		return
+	}
 		return
 	}
 
-	if err := Verify(key, expectedSignedString); err != nil {
+	if err := Verify(key, []byte(expectedSignedString)); err != nil {
 		t.Errorf("verify: %s", err)
 		return
 	}
 
 	brokenDoc := strings.Replace(expectedSignedString, "Hello", "Goodbye", 1)
-	err = Verify(key, brokenDoc)
+	err = Verify(key, []byte(brokenDoc))
 	if err != ErrVerificationFailed {
 		t.Errorf("verify: expected verification failed, got %s", err)
 		return