[jira] [Updated] (CAMEL-25355) camel-support - an empty charset parameter of the Content-Type (charset=) sets an empty CamelCharsetName, and converting the body then fails (servlet, Jetty and HTTP producer)

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

     [ https://issues.apache.org/jira/browse/CAMEL-25355?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Claus Ibsen updated CAMEL-25355:
--------------------------------
    Fix Version/s: 4.23.0

> camel-support - an empty charset parameter of the Content-Type (charset=) sets an empty CamelCharsetName, and converting the body then fails (servlet, Jetty and HTTP producer)
> -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: CAMEL-25355
>                 URL: https://issues.apache.org/jira/browse/CAMEL-25355
>             Project: Camel
>          Issue Type: Bug
>          Components: camel-core, camel-http, camel-http-common, camel-jetty, camel-servlet, camel-support
>            Reporter: shashank
>            Assignee: shashank
>            Priority: Minor
>             Fix For: 4.23.0
>
>
> The shared helpers that read the charset parameter of a {{Content-Type}} return an empty name for an empty value, such as {{text/plain; charset=}}, {{charset=""}} or {{charset=; format=flowed}}:
> * {{IOHelper.getCharsetNameFromContentType}} (camel-util) returns {{""}} instead of its default {{UTF-8}};
> * {{HttpUtil.getCharsetFromContentType}} (camel-support, used by {{HttpUtil.setCharsetFromContentType}} and {{org.apache.camel.http.common.HttpHelper.setCharsetFromContentType}}) returns {{""}} instead of {{null}}.
> The callers store this as the {{CamelCharsetName}} exchange property: {{CamelServlet}} (servlet consumer), {{CamelContinuationServlet}} (Jetty consumer), {{HttpProducer}} (response headers and response body), {{DefaultVertxHttpBinding}} (vertx-http producer). {{DefaultHttpBinding.readHeaders}} does the same with {{HttpServletRequest.getCharacterEncoding()}}, which is also {{""}} for these values on Tomcat ({{charset=}}, {{charset=""}}) and Undertow ({{charset=""}}, {{charset=; ...}}). Every later conversion of the body that uses the exchange charset then fails in {{Charset.forName("")}}:
> {noformat}
> org.apache.camel.TypeConversionException: Error during type conversion from type: byte[] to the required type: java.lang.String due to java.nio.charset.IllegalCharsetNameException:
>     at java.nio.charset.Charset.forName(Charset.java:539)
>     at org.apache.camel.support.ExchangeHelper.getCharset(ExchangeHelper.java:1005)
> {noformat}
> So a servlet or Jetty route that reads the body as a String answers 500, and an HTTP producer cannot read the response body as a String. The form parser of {{DefaultHttpBinding}} ({{application/x-www-form-urlencoded; charset=""}}) also fails ({{URLDecoder.decode(.., "")}}).
> {{UndertowHelper.getCharsetFromContentType}} already treats an empty value as no charset, and the same was done for {{NettyHttpHelper}} in CAMEL-25305 (raised by Claus Ibsen in the review).
> h3. Reproduction
> * camel-util {{IOHelperTest.testCharsetEmpty}}: {{expected: <UTF-8> but was: <>}}; camel-support new {{HttpUtilTest}}: {{expected: <null> but was: <>}}.
> * camel-servlet new {{ServletEmptyCharsetParameterTest}} (embedded Undertow): a POST with {{text/plain; charset=; format=flowed}}, {{charset=""}} or {{charset= ;format=flowed}} to a route doing {{convertBodyTo(String.class)}}, and a form POST with {{charset=""}}: all 4 answer 500 on main.
> * camel-jetty new {{JettyEmptyCharsetParameterTest}}: a POST with {{text/plain; charset=}}: 500 on main.
> * camel-http new {{HttpProducerEmptyCharsetParameterTest}}: a response with any of the three empty forms: {{TypeConversionException}} on main (3 of 3).
> All fail in two runs on main.
> h3. Proposed fix
> Treat an empty (or blank) charset value as no charset, as {{UndertowHelper}} and {{NettyHttpHelper}} do: {{IOHelper.getCharsetNameFromContentType}} returns its default {{UTF-8}}, {{HttpUtil.getCharsetFromContentType}} returns {{null}} (so no property is set), and {{DefaultHttpBinding}} ignores an empty {{getCharacterEncoding()}} (and parses a form as UTF-8, as without a charset). Content types with a charset, or without one, are handled as before. No upgrade note: the only change is for requests and responses that failed before, apart from the corner case below.
> Other callers of {{IOHelper.getCharsetNameFromContentType}} see {{UTF-8}} instead of {{""}} for an empty charset parameter: the vertx-http producer ({{DefaultVertxHttpBinding}}) stored {{""}} as {{CamelCharsetName}} and failed in the same way, and now uses UTF-8; {{VertxPlatformHttpSupport}} (CAMEL-25217) treated {{""}} as no charset and wrote a String response as UTF-8, which it still does. {{VertxBufferConverter}} and {{VertxHttpHelper.getCharsetFromExchange}} fell back to the {{CamelCharsetName}} exchange property for {{""}}; they now use UTF-8, as they already did for a Content-Type without a charset. So a {{Buffer}}/{{String}} conversion for a message whose Content-Type has an empty charset parameter and that also has a {{CamelCharsetName}} other than UTF-8 now uses UTF-8.
> Not in Camel, so not changed: the embedded Undertow itself fails on a {{charset=}} at the very end of the header ({{StringIndexOutOfBoundsException}} in {{Headers.extractQuotedValueFromHeader}}), and Jetty 12 itself rejects {{charset=""}} and {{charset=; ...}} in {{getContentType()}}.
> Together with the CAMEL-25316 and CAMEL-25133 changes to {{DefaultHttpBinding}} (merged without conflict) the camel-util, camel-support, camel-http-base, camel-http-common, camel-servlet, camel-jetty-common, camel-http, camel-jetty (except the environment-dependent {{JettyXsltHttpTemplateTest}}), camel-vertx-http and camel-platform-http-vertx tests pass.
> Affected: 4.14.x, 4.18.x and main (same code).
> Priority Minor: only requests or responses with a malformed (empty) charset parameter are affected, but they fail instead of being read as UTF-8.
> Duplicate check (2026-10-05): JIRA "IllegalCharsetNameException" (3 issues, none on this), "getCharsetNameFromContentType" (4: CAMEL-25295, CAMEL-12395, CAMEL-25084, CAMEL-25217), "normalizeCharset" (CAMEL-12424, a charset that is not the last parameter), "HttpUtil" with charset (CAMEL-25305, CAMEL-24594), summary "empty charset" (none). GitHub pull requests "empty charset", "getCharsetNameFromContentType", "IllegalCharsetNameException": only the merged CAMEL-25305, CAMEL-25295, CAMEL-25084 and CAMEL-25217.
> _Filed with Claude Code on behalf of allthingssecurity._



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