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https://issues.apache.org/jira/browse/CAMEL-25248?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Claus Ibsen resolved CAMEL-25248.
---------------------------------
Resolution: Fixed
Merged via https://github.com/apache/camel/pull/27245
> camel-undertow - a String body is always sent as UTF-8, even when the
> Content-Type declares another charset
> -----------------------------------------------------------------------------------------------------------
>
> Key: CAMEL-25248
> URL: https://issues.apache.org/jira/browse/CAMEL-25248
> Project: Camel
> Issue Type: Bug
> Components: camel-undertow
> Reporter: shashank
> Assignee: shashank
> Priority: Minor
> Fix For: 4.23.0
>
>
> The Undertow consumer writes a response body with
> {code:java}
> ByteBuffer bodyAsByteBuffer = tc.mandatoryConvertTo(ByteBuffer.class, body);
> // UndertowConsumer.sendResponse
> {code}
> and the producer a request body with {{tc.tryConvertTo(ByteBuffer.class,
> body)}} ({{UndertowProducer.process}}). Both convert *without the exchange*,
> so {{NIOConverter.toByteBuffer(String, Exchange)}} gets {{null}} and encodes
> a {{String}} in the default charset (UTF-8), whatever the message says:
> * a route that sets {{Content-Type: text/plain; charset=ISO-8859-1}} and a
> {{String}} body: {{Grüße aus Köln}} (14 characters) is sent as 17 bytes of
> UTF-8 labelled ISO-8859-1, and the client reads {{Grü...}};
> * an echo, or any route that keeps the request {{Content-Type}}: the consumer
> reads an ISO-8859-1 request correctly (it sets {{CamelCharsetName}} from the
> request charset), but the {{String}} reply under the same {{Content-Type}} is
> UTF-8;
> * the producer: {{to("undertow:http://...";)}} with a {{String}} body and
> {{Content-Type: text/plain; charset=ISO-8859-1}} sends UTF-8 bytes under that
> header.
> {{byte[]}}, {{InputStream}} and other non-{{String}} bodies, and ASCII text,
> are not affected. The other HTTP components honour the charset:
> camel-servlet/camel-jetty ({{DefaultHttpBinding}}) write a {{String}} in
> {{CamelCharsetName}}, camel-http uses {{CamelCharsetName}} or the
> {{Content-Type}} charset, camel-netty-http converts with the exchange, and
> camel-platform-http-vertx uses the {{Content-Type}} charset since CAMEL-25217.
> h3. Reproduction
> {code:java}
> from("undertow:http://localhost:8080/latin1";)
> .setHeader(Exchange.CONTENT_TYPE, constant("text/plain;
> charset=ISO-8859-1"))
> .setBody(constant("Grüße aus Köln"));
> from("undertow:http://localhost:8080/echo";)
> .convertBodyTo(String.class);
> {code}
> {{GET /latin1}} returns 17 bytes (UTF-8) instead of 14; {{POST /echo}} with
> {{Content-Type: text/plain; charset=ISO-8859-1}} and the 14 ISO-8859-1 bytes
> returns 17 bytes;
> {{template.sendBodyAndHeader("undertow:http://localhost:8080/received";,
> "Grüße aus Köln", "Content-Type", "text/plain; charset=ISO-8859-1")}}
> delivers 17 bytes. A unit test with these three cases fails on main ({{array
> lengths differ, expected: <14> but was: <17>}}); a control with
> {{Content-Type: text/plain}} (UTF-8 expected) passes.
> h3. Proposed fix
> A {{String}} body is encoded in the charset declared by the {{Content-Type}}
> of the request or response being sent (new
> {{UndertowHelper.toByteBuffer(String, String)}}, used by the consumer and the
> producer), as CAMEL-25217 does for camel-platform-http-vertx. Without a
> declared charset (or with an unknown one) the body is converted as today
> (UTF-8), and other bodies are converted as today. {{CamelCharsetName}} is
> deliberately not used as a fallback: Undertow cannot declare it in the header
> afterwards (camel-servlet does, with {{setCharacterEncoding}}), so a response
> to an ISO-8859-1 request with {{Content-Type: application/json}} would be
> written in ISO-8859-1 while the client reads UTF-8.
> With the fix the new test (5 cases, including that last one) and the whole
> camel-undertow suite pass (196 tests, 1 skipped). Only messages that declare
> a charset other than UTF-8 change, so the change gets an upgrade guide note.
> Affected: 4.14.x, 4.18.x (same code) and main. The fix does not read
> {{CamelCharsetName}}, so it can be backported on its own (on 4.14.x/4.18.x
> the consumer still sets it to ISO-8859-1 for a request without charset;
> 892be63447 changed that on main).
> Duplicate check (2026-10-01): JIRA component camel-undertow with "charset",
> "encoding" or "UTF-8", and summary "undertow" with
> "charset"/"encoding"/"ISO-8859-1": only CAMEL-11392 (ByteBuffer overflow with
> multibyte characters, fixed 2017), CAMEL-12247, CAMEL-10803; nothing about
> the charset of a String body. GitHub pull requests "undertow charset": none.
> _Filed with Claude Code on behalf of allthingssecurity._
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