protected XMLSignatureInput enginePerformTransform()

in src/main/java/org/apache/xml/security/transforms/implementations/TransformXSLT.java [74:167]
63 lines of code
8 McCabe index (conditional complexity)

    protected XMLSignatureInput enginePerformTransform(
        XMLSignatureInput input, OutputStream baos, Element transformElement,
        String baseURI, boolean secureValidation
    ) throws IOException, TransformationException {
        try {
            Element xsltElement =
                XMLUtils.selectNode(transformElement.getFirstChild(), XSLTSpecNS, "stylesheet", 0);
            if (xsltElement == null) {
                xsltElement =
                    XMLUtils.selectNode(transformElement.getFirstChild(), XSLTSpecNS, "transform", 0);
            }
            if (xsltElement == null) {
                Object[] exArgs = { "xslt:stylesheet", "Transform" };

                throw new TransformationException("xml.WrongContent", exArgs);
            }

            TransformerFactory tFactory = TransformerFactory.newInstance();
            // Process XSLT stylesheets in a secure manner
            tFactory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, Boolean.TRUE);
            if (secureValidation) {
                try {
                    tFactory.setAttribute(XMLConstants.ACCESS_EXTERNAL_DTD, "");
                    tFactory.setAttribute(XMLConstants.ACCESS_EXTERNAL_STYLESHEET, "");
                } catch (IllegalArgumentException ex) {
                    // ignore
                }
            }

            /*
             * This transform requires an octet stream as input. If the actual
             * input is an XPath node-set, then the signature application should
             * attempt to convert it to octets (apply Canonical XML]) as described
             * in the Reference Processing Model (section 4.3.3.2).
             */
            Source stylesheet;

            /*
             * This complicated transformation of the stylesheet itself is necessary
             * because of the need to get the pure style sheet. If we simply say
             * Source stylesheet = new DOMSource(this.xsltElement);
             * whereby this.xsltElement is not the rootElement of the Document,
             * this causes problems;
             * so we convert the stylesheet to byte[] and use this as input stream
             */
            {
                try (ByteArrayOutputStream os = new ByteArrayOutputStream()) {
                    Transformer transformer = tFactory.newTransformer();
                    DOMSource source = new DOMSource(xsltElement);
                    StreamResult result = new StreamResult(os);

                    transformer.transform(source, result);

                    stylesheet =
                        new StreamSource(new ByteArrayInputStream(os.toByteArray()));
                }
            }

            Transformer transformer = tFactory.newTransformer(stylesheet);

            // Force Xalan to use \n as line separator on all OSes. This
            // avoids OS specific signature validation failures due to line
            // separator differences in the transformed output. Unfortunately,
            // this is not a standard JAXP property so will not work with non-Xalan
            // implementations.
            try {
                transformer.setOutputProperty("{http://xml.apache.org/xalan}line-separator", "\n");
            } catch (Exception e) {
                LOG.log(Level.WARNING, "Unable to set Xalan line-separator property: " + e.getMessage());
            }

            try (InputStream is = new ByteArrayInputStream(input.getBytes())) {
                Source xmlSource = new StreamSource(is);
                if (baos == null) {
                    try (ByteArrayOutputStream baos1 = new ByteArrayOutputStream()) {
                        StreamResult outputTarget = new StreamResult(baos1);
                        transformer.transform(xmlSource, outputTarget);
                        XMLSignatureInput output = new XMLSignatureByteInput(baos1.toByteArray());
                        output.setSecureValidation(secureValidation);
                        return output;
                    }
                }
                StreamResult outputTarget = new StreamResult(baos);

                transformer.transform(xmlSource, outputTarget);
            }
            XMLSignatureInput output = new XMLSignatureByteInput(null);
            output.setSecureValidation(secureValidation);
            output.setOutputStream(baos);
            return output;
        } catch (XMLSecurityException | TransformerException ex) {
            throw new TransformationException(ex);
        }
    }