ZCU-PUB/fix: RFC 5987 Content-Disposition for single-file + allzip download (backport #1368)

[milanmajchrak]

Backport of #1368 to customer/zcu-pub. Fixes the wrong filename when downloading a file whose name has diacritics — both causes.

Customer branches never merge dtq-dev (they sit ~258 commits behind and take individual backports), so this cannot ride along on #1368.

Evidence

The before/after A/B run is in #1368 — two real backend images against the same database. It was run on the dtq-dev pair, not on this branch, so treat it as evidence for the shared fix rather than for this backport specifically.

What's fixed

1. allzip — MetadataBitstreamController built attachment;filename="<raw name>" with no encoding. Raw UTF-8 in a header makes Tomcat drop the header entirely, so the browser gets no filename at all and falls back to the URL segment (allzip.zip). A " in an item name closed the quoted-string early (ERR_RESPONSE_HEADERS_MULTIPLE_CONTENT_DISPOSITION).
2. Single file — HttpHeadersInitializer used MimeUtility.encodeText, i.e. an RFC 2047 encoded-word, which RFC 6266 App. C.1 forbids in HTTP. Cherry-pick of vanilla fe4077acee (#11269 → 7.6.6). Note Chrome and Firefox decode RFC 2047 anyway, so this half is invisible to them — it bites Safari and curl -OJ.

As on #1368, MetadataBitstreamController carries its own private copy of vanilla's createFallbackAsciiName / createEncodedUtf8Name rather than a shared fork helper: it is a fork-only class with no upstream counterpart, so copying keeps it tracking vanilla and adds no API to maintain.

Differences from #1368 — please check these in review

• BitstreamByHandleRestController does not exist on this branch (the curl endpoint from UFAL/Fix: add bitstream download-by-handle endpoint for curl instructions #1252 was never backported here), so it is not touched.
• The HttpHeadersInitializer cherry-pick conflicted and was hand-resolved. This branch's copy predates vanilla's isNullOrEmpty(disposition) guard and has its own METHOD_HEAD early-return; I kept this branch's structure and swapped only the encoding. Unlike on dtq-dev, this file is not byte-identical to vanilla — it already wasn't.

One deviation from vanilla

The ASCII fallback escapes \ and "; vanilla omits this, so a name containing a quote breaks the header even on a clean 7.6.6. Copying vanilla verbatim would have regressed #1267. Marked in a comment at the call site.

Verified

• mvn test-compile on dspace-api + dspace-server-webapp — pass
• checkstyle is not wired up on this 7.6.1 branch, so it is a no-op here; the same code passes it on dtq-dev
• ITs not run locally (need Postgres + Solr) — left to CI
• the A/B run was done on the dtq-dev pair, not on this branch

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Pull request overview

Backports RFC 5987-compliant Content-Disposition handling to prevent mangled diacritics and malformed headers in both single-bitstream downloads and “allzip” downloads.

Changes:

• Updated single-file download responses to emit both filename (ASCII fallback) and filename* (RFC 5987 encoded UTF-8) instead of RFC 2047 encoded-words.
• Introduced ContentDispositionUtils and applied it to MetadataBitstreamController to safely build allzip Content-Disposition.
• Added/updated integration + unit tests covering non-ASCII, spaces, and quoting behavior.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
dspace-server-webapp/src/main/java/org/dspace/app/rest/utils/HttpHeadersInitializer.java	Switches single-file Content-Disposition to RFC 5987-style filename* + ASCII fallback.
dspace-server-webapp/src/main/java/org/dspace/app/rest/MetadataBitstreamController.java	Uses shared utility to generate safe allzip Content-Disposition.
dspace-api/src/main/java/org/dspace/util/ContentDispositionUtils.java	New utility for building safe RFC 5987 Content-Disposition values.
dspace-api/src/test/java/org/dspace/util/ContentDispositionUtilsTest.java	Adds unit tests for escaping, encoding, and control-char handling.
dspace-server-webapp/src/test/java/org/dspace/app/rest/BitstreamRestControllerIT.java	Updates expectations for new header format on single-file download endpoint.
dspace-server-webapp/src/test/java/org/dspace/app/rest/MetadataBitstreamControllerIT.java	Adds IT coverage for quotes + diacritics in allzip filenames.

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