[jira] [Resolved] (CAMEL-23891) camel-mail: apply inbound Camel* header filtering in MimeMultipartDataFormat unmarshal (headersInline=true), consistent with the mail consumer

["Andrea Cosentino (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CAMEL-23891?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andrea Cosentino resolved CAMEL-23891.
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    Resolution: Fixed

> camel-mail: apply inbound Camel* header filtering in MimeMultipartDataFormat unmarshal (headersInline=true), consistent with the mail consumer
> ----------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: CAMEL-23891
>                 URL: https://issues.apache.org/jira/browse/CAMEL-23891
>             Project: Camel
>          Issue Type: Improvement
>          Components: camel-mail
>            Reporter: Andrea Cosentino
>            Assignee: Andrea Cosentino
>            Priority: Major
>             Fix For: 4.14.9, 4.18.4, 4.22.0
>
>
> When {{MimeMultipartDataFormat}} unmarshals a MIME message with {{headersInline=true}}, {{copyNonStandardHeaders()}} copies every MIME header (except {{Message-ID}}, {{MIME-Version}} and {{Content-Type}}) directly into the Camel message header map via {{Message.setHeader(...)}}, with no {{HeaderFilterStrategy}} applied. As a result, MIME header names in Camel's internal {{Camel*}} / {{org.apache.camel.*}} namespace are promoted into the {{Exchange}} as-is.
> This is inconsistent with:
> * the camel-mail _consumer_ path, which applies {{MailHeaderFilterStrategy}} (extends {{DefaultHeaderFilterStrategy}}) and filters the {{Camel*}} / {{org.apache.camel.*}} namespace case-insensitively on the inbound direction;
> * the data format's own _marshal_ path, where inline headers are copied only when they match an explicit {{includeHeaders}} pattern (opt-in), whereas the unmarshal path copies everything;
> * the general convention that inbound mappers apply a strict, case-insensitive {{HeaderFilterStrategy}} for the {{Camel*}} namespace.
> h4. Proposed change
> * In {{copyNonStandardHeaders(...)}} (and, for consistency, the attachment-header copy in {{extractAttachments(...)}}), skip header names in the {{Camel*}} / {{org.apache.camel.*}} namespace, matched case-insensitively -- e.g. by delegating to {{DefaultHeaderFilterStrategy.applyFilterToExternalHeaders(...)}} rather than re-implementing prefix checks.
> * Optionally expose a configurable {{HeaderFilterStrategy}} on the data format (defaulting to the strict behaviour) so a route author who genuinely needs such headers can opt in explicitly, preserving backwards compatibility where required.
> * Add unit tests: (a) an inbound {{Camel*}} MIME header is not promoted by default; (b) ordinary application headers (e.g. {{X-...}}) still pass through; (c) case-insensitive matching ({{camelXxx}}, {{CAMELXxx}}).
> h4. Affected files
> * {{components/camel-mail/src/main/java/org/apache/camel/dataformat/mime/multipart/MimeMultipartDataFormat.java}}
> * tests under {{components/camel-mail/src/test/java/...}}
> h4. Documentation
> Note the behaviour change in the camel-mail data format docs and the 4.x upgrade guide: default-deny of inbound {{Camel*}} headers on {{headersInline=true}} unmarshal is a potential behaviour change for routes relying on the prior pass-through.
> h4. Backport
> The code is identical on {{main}}, {{camel-4.18.x}} and {{camel-4.14.x}} (present since 2.17.0). To be backported to the active maintenance lines (4.18.4 and 4.14.9). The freshly-cut {{camel-4.21.x}} line is also affected; a 4.21.1 backport should be included if that line receives a maintenance release.



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