Lenient recovery from duplicate Content-Type parameters - #10
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jakeesmael
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Aug 22, 2026
jakeesmael
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Aug 24, 2026
When mime.ParseMediaType fails due to duplicate parameter names, strip the duplicates (keeping the first occurrence) and retry. On success, return the recovered media type and params alongside a MalformedHeaderError so callers can distinguish a recovered-but-valid header from a genuinely unparseable one. Exports IsMalformedHeader so consumers (e.g. go-mantis) can opt in to using the recovered values while still observing the malformed-header signal. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
…covery Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
…ty signal Callers can check params != nil to determine whether recovered values are usable, regardless of whether err is non-nil. The invariant is: params != nil means the values are safe to use. This removes unnecessary API surface. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
My Summary:
Apple Mail renders both plaintext and HTML when duplicate Content-Type parameters exist. We need to emulate this permissive behavior in order to parse messages and detect phishes that could be apparent in Apple Mail.
This change adds a
deduplicateContentTypeParamsfunction to deduplicate Content-Type parameters. ThededuplicateContentTypeParamsshort circuits when possible and avoids rebuilding the string with new allocations until we know there is a duplicate.🤖 Generated with Claude Code