[jira] [Assigned] (CAMEL-24406) camel-xml-jaxp: XmlConverter.toDOMDocument throws SAXParseException for non-XML content (Content is not allowed in prolog)

["Claus Ibsen (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CAMEL-24406?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Claus Ibsen reassigned CAMEL-24406:
-----------------------------------

    Assignee: mayur mohan

> camel-xml-jaxp: XmlConverter.toDOMDocument throws SAXParseException for non-XML content (Content is not allowed in prolog)
> --------------------------------------------------------------------------------------------------------------------------
>
>                 Key: CAMEL-24406
>                 URL: https://issues.apache.org/jira/browse/CAMEL-24406
>             Project: Camel
>          Issue Type: Improvement
>          Components: camel-core-xml
>            Reporter: mayur mohan
>            Assignee: mayur mohan
>            Priority: Minor
>             Fix For: 4.23.0
>
>
> h2. Problem
> When a ByteArrayInputStreamCache (or byte[]) carrying a non-XML response body (empty body, JSON error page, plain-text HTTP response, BOM-only) is passed to XmlConverter.toDOMDocument, the JDK XML parser throws:
> {noformat}
> org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; Content is not allowed in prolog.
> {noformat}
> Surfaced as:
> {noformat}
> Cannot read from xml stream. Reason: Error during type conversion from type: org.apache.camel.converter.stream.ByteArrayInputStreamCache to the required type: org.w3c.dom.Document ... due to org.xml.sax.SAXParseException: Content is not allowed in prolog.
> {noformat}
> h2. Why Fix required
>  * Currently Invalid / non-XML content does *not* just produce a clean exception – it forces memory intensive  DOM construction first.
>  * in distributed communication systems, messages are Retried multiple times, this increases the cost of compute and memory in cloud runtime. because the same erroneous stream objects are rebuilt multiple time. where simple precheck for consistency and validity is introduced before expensive operations triggered. 
>  * Under load or with large bad payloads this becomes a significant heap-memory and GC problem, even though the final outcome is always a parse failure.
>  * In our just one production landscape 5 million such errors seen with different tenants.
> h2. Stack Trace
> {noformat}
> org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; Content is not allowed in prolog.
>     at java.xml/com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:204)
>     at java.xml/com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.fatalError(ErrorHandlerWrapper.java:178)
>     at java.xml/com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:400)
>     at java.xml/com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:978)
>     at java.xml/javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:122)
>     at org.apache.camel.converter.jaxp.XmlConverter.toDOMDocument(XmlConverter.java:661)
>     at org.apache.camel.converter.jaxp.CamelXmlJaxpBulkConverterLoader.doConvertTo(CamelXmlJaxpBulkConverterLoader.java:317)
>     at org.apache.camel.converter.jaxp.CamelXmlJaxpBulkConverterLoader.convertTo(CamelXmlJaxpBulkConverterLoader.java:51)
>     at org.apache.camel.spi.BulkTypeConverters.convertTo(BulkTypeConverters.java:122)
>     at org.apache.camel.component.cxf.converter.CxfPayloadConverter.convertTo(CxfPayloadConverter.java:165)
>     at org.apache.camel.component.cxf.converter.CxfPayloadConverterLoader.lambda(CxfPayloadConverterLoader.java:68)
>     at org.apache.camel.support.SimpleTypeConverter.convertTo(SimpleTypeConverter.java:101)
>     at org.apache.camel.impl.converter.CoreTypeConverterRegistry.doConvertTo(CoreTypeConverterRegistry.java:516)
>     at org.apache.camel.impl.converter.CoreTypeConverterRegistry.convertTo(CoreTypeConverterRegistry.java:203)
>     at org.apache.camel.core.osgi.OsgiTypeConverter.convertTo(OsgiTypeConverter.java:138)
>     at org.apache.camel.support.MessageSupport.getBody(MessageSupport.java:96)
>     at org.apache.camel.component.cxf.DefaultCxfBinding.getBodyFromCamel(DefaultCxfBinding.java:1019)
>     at org.apache.camel.component.cxf.DefaultCxfBinding.populateCxfResponseFromExchange(DefaultCxfBinding.java:461)
>     at org.apache.camel.component.cxf.CxfConsumer.CxfConsumerInvoker.setResponseBack(CxfConsumer.java:324)
>     at org.apache.camel.component.cxf.CxfConsumer.CxfConsumerInvoker.syncInvoke(CxfConsumer.java:248)
> {noformat}
> h2. Root Cause
> XmlConverter.toDOMDocument(byte[], Exchange) and toDOMDocument(StreamCache, Exchange) pass the content directly to DocumentBuilder.parse() without first checking whether it could plausibly be XML. Any content whose first non-whitespace byte is not < causes an immediate SAXParseException deep inside the JDK parser.
> h2. Fix
> Add a cheap static looksLikeXml(byte[]) helper that inspects only the first few bytes (handles UTF-8 BOM, UTF-16 BE/LE BOM, leading whitespace). Guard the two toDOMDocument overloads that take byte[] and StreamCache to return null when content is definitely not XML. Use @Converter(allowNull = true) so the Camel type-converter framework falls through gracefully.
> h2. Files Changed
> core/camel-xml-jaxp/src/main/java/org/apache/camel/converter/jaxp/XmlConverter.java
> core/camel-xml-jaxp/src/test/java/org/apache/camel/converter/jaxp/XmlConverterPrologTest.java (new, 13 tests)
> h2. Test Results
> {noformat}
> Tests run: 13, Failures: 0, Errors: 0, Skipped: 0  [JDK 21 / Maven 3.9]
> BUILD SUCCESS
> {noformat}



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