X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?a=blobdiff_plain;f=opendaylight%2Fnetconf%2Fnetconf-netty-util%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fcontroller%2Fnetconf%2Fnettyutil%2Fhandler%2FNetconfXMLToMessageDecoder.java;h=07fb789a08a5c1d6170df05c6e0bbf6b339a3e6e;hb=refs%2Fchanges%2F13%2F23413%2F26;hp=69c0d53fc12144ad7e780126e5f8d3fe6372a571;hpb=b80124e3f7b11cf2f5e5bd4a6b033d855ff4d0d4;p=controller.git

diff --git a/opendaylight/netconf/netconf-netty-util/src/main/java/org/opendaylight/controller/netconf/nettyutil/handler/NetconfXMLToMessageDecoder.java b/opendaylight/netconf/netconf-netty-util/src/main/java/org/opendaylight/controller/netconf/nettyutil/handler/NetconfXMLToMessageDecoder.java
index 69c0d53fc1..07fb789a08 100644
--- a/opendaylight/netconf/netconf-netty-util/src/main/java/org/opendaylight/controller/netconf/nettyutil/handler/NetconfXMLToMessageDecoder.java
+++ b/opendaylight/netconf/netconf-netty-util/src/main/java/org/opendaylight/controller/netconf/nettyutil/handler/NetconfXMLToMessageDecoder.java
@@ -7,33 +7,80 @@
  */
 package org.opendaylight.controller.netconf.nettyutil.handler;
 
-import java.util.List;
-
-import org.opendaylight.controller.netconf.api.NetconfMessage;
-import org.opendaylight.controller.netconf.util.xml.XmlUtil;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import com.google.common.annotations.VisibleForTesting;
-
 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;
+import java.util.List;
+import org.opendaylight.controller.config.util.xml.XmlUtil;
+import org.opendaylight.controller.netconf.api.NetconfMessage;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.xml.sax.SAXException;
 
 public final class NetconfXMLToMessageDecoder extends ByteToMessageDecoder {
     private static final Logger LOG = LoggerFactory.getLogger(NetconfXMLToMessageDecoder.class);
 
     @Override
-    @VisibleForTesting
-    public void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
+    public void decode(final ChannelHandlerContext ctx, final ByteBuf in, final List<Object> out) throws IOException, SAXException {
+        if (in.isReadable()) {
+            if (LOG.isTraceEnabled()) {
+                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.
+             */
 
-        if (in.readableBytes() != 0) {
-            LOG.trace("Received to decode: {}", ByteBufUtil.hexDump(in));
+            // 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;
+    }
 }