import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufInputStream;
import io.netty.buffer.ByteBufUtil;
+import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;
import java.io.IOException;
LOG.trace("Received to decode: {}", ByteBufUtil.hexDump(in));
}
+ /* According to the XML 1.0 specifications, when there is an XML declaration
+ * at the beginning of an XML document, it is invalid to have
+ * white spaces before that declaration (reminder: a XML declaration looks like:
+ * <?xml version="1.0" encoding="UTF-8"?>). In contrast, when there is no XML declaration,
+ * it is valid to have white spaces at the beginning of the document.
+ *
+ * When they send a NETCONF message, several NETCONF servers start with a new line (either
+ * LF or CRLF), presumably to improve readability in interactive sessions with a human being.
+ * Some NETCONF servers send an XML declaration, some others do not.
+ *
+ * If a server starts a NETCONF message with white spaces and follows with an XML
+ * declaration, XmlUtil.readXmlToDocument() will fail because this is invalid XML.
+ * But in the spirit of the "NETCONF over SSH" RFC 4742 and to improve interoperability, we want
+ * to accept those messages.
+ *
+ * To do this, the following code strips the leading bytes before the start of the XML messages.
+ */
+
+ // Skip all leading whitespaces by moving the reader index to the first non whitespace character
+ while (in.isReadable()) {
+ if (!isWhitespace(in.readByte())) {
+ // return reader index to the first non whitespace character
+ in.readerIndex(in.readerIndex() - 1);
+ break;
+ }
+ }
+
+ // Warn about leading whitespaces
+ if (in.readerIndex() != 0 && LOG.isWarnEnabled()) {
+ final byte[] strippedBytes = new byte[in.readerIndex()];
+ in.getBytes(0, strippedBytes, 0, in.readerIndex());
+ LOG.warn("XML message with unwanted leading bytes detected. Discarded the {} leading byte(s): '{}'",
+ in.readerIndex(), ByteBufUtil.hexDump(Unpooled.wrappedBuffer(strippedBytes)));
+ }
+ }
+ if (in.isReadable()) {
out.add(new NetconfMessage(XmlUtil.readXmlToDocument(new ByteBufInputStream(in))));
} else {
LOG.debug("No more content in incoming buffer.");
}
}
+
+ /**
+ * Check whether a byte is whitespace/control character. Considered whitespace characters: <br/>
+ * SPACE, \t, \n, \v, \r, \f
+ *
+ * @param b byte to check
+ * @return true if the byte is a whitespace/control character
+ */
+ private static boolean isWhitespace(final byte b) {
+ return b <= 0x0d && b >= 0x09 || b == 0x20;
+ }
}
import io.netty.buffer.Unpooled;
import java.util.ArrayList;
import org.junit.Test;
+import org.xml.sax.SAXParseException;
public class NetconfXMLToMessageDecoderTest {
new NetconfXMLToMessageDecoder().decode(null, Unpooled.wrappedBuffer("<msg/>".getBytes()), out);
assertEquals(1, out.size());
}
-}
\ No newline at end of file
+
+ @Test
+ public void testDecodeWithLeadingLFAndXmlDecl() throws Exception {
+ /* Test that we accept XML documents with a line feed (0x0a) before the
+ * XML declaration in the XML prologue.
+ * A leading LF is the case reported in BUG-2838.
+ */
+ final ArrayList<Object> out = Lists.newArrayList();
+ new NetconfXMLToMessageDecoder().decode(null, Unpooled.wrappedBuffer("\n<?xml version=\"1.0\" encoding=\"UTF-8\"?><msg/>".getBytes()), out);
+ assertEquals(1, out.size());
+ }
+
+ @Test
+ public void testDecodeWithLeadingCRLFAndXmlDecl() throws Exception {
+ /* Test that we accept XML documents with both a carriage return and
+ * line feed (0x0d 0x0a) before the XML declaration in the XML prologue.
+ * Leading CRLF can be seen with some Cisco routers
+ * (eg CSR1000V running IOS 15.4(1)S)
+ */
+ final ArrayList<Object> out = Lists.newArrayList();
+ new NetconfXMLToMessageDecoder().decode(null, Unpooled.wrappedBuffer("\r\n<?xml version=\"1.0\" encoding=\"UTF-8\"?><msg/>".getBytes()), out);
+ assertEquals(1, out.size());
+ }
+
+ @Test(expected=SAXParseException.class)
+ public void testDecodeGibberish() throws Exception {
+ /* Test that we reject inputs where we cannot find the xml start '<' character */
+ final ArrayList<Object> out = Lists.newArrayList();
+ new NetconfXMLToMessageDecoder().decode(null, Unpooled.wrappedBuffer("\r\n?xml version>".getBytes()), out);
+ assertEquals(1, out.size());
+ }
+
+ @Test
+ public void testDecodeOnlyWhitespaces() throws Exception {
+ /* Test that we handle properly a bunch of whitespaces.
+ */
+ final ArrayList<Object> out = Lists.newArrayList();
+ new NetconfXMLToMessageDecoder().decode(null, Unpooled.wrappedBuffer("\r\n".getBytes()), out);
+ assertEquals(0, out.size());
+ }
+
+ @Test
+ public void testDecodeWithAllWhitespaces() throws Exception {
+ /* Test that every whitespace we want to skip is actually skipped.
+ */
+
+ final ArrayList<Object> out = Lists.newArrayList();
+ byte whitespaces[] = {' ', '\t', '\n', '\r', '\f', 0x0b /* vertical tab */};
+ new NetconfXMLToMessageDecoder().decode(
+ null,
+ Unpooled.copiedBuffer(
+ Unpooled.wrappedBuffer(whitespaces),
+ Unpooled.wrappedBuffer("<?xml version=\"1.0\" encoding=\"UTF-8\"?><msg/>".getBytes())),
+ out);
+ assertEquals(1, out.size());
+ }
+}
+
Code Review / controller.git / commitdiff