fix(gmail): prevent URL corruption in quoted-printable decoding#186
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100menotu001 wants to merge 2 commits intosteipete:mainfrom
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fix(gmail): prevent URL corruption in quoted-printable decoding#186100menotu001 wants to merge 2 commits intosteipete:mainfrom
100menotu001 wants to merge 2 commits intosteipete:mainfrom
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February 4, 2026 17:39
When Gmail API returns already-decoded content (format=full), the Content-Transfer-Encoding header may still say 'quoted-printable'. Previously, we would attempt to QP-decode again, causing raw '=' characters in URLs to be replaced with U+FFFD (replacement char). This adds looksLikeQuotedPrintable() to detect actual QP sequences (=XX hex or =CRLF soft breaks) and skip decoding when content appears pre-decoded. Fixes steipete#159
Matt's security review caught that URLs like '?foo=bar' would incorrectly trigger QP detection because '=ba' matches as hex digits. Changed to only match UPPERCASE hex (0-9, A-F) since: - RFC 2045 recommends uppercase for QP encoding - Most encoders use uppercase in practice - This avoids false positives from lowercase URL params
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Summary
Fixes #159 — URLs with
=characters were being corrupted to U+FFFD when emails hadContent-Transfer-Encoding: quoted-printablebut content was already decoded by Gmail API.Root Cause
Gmail API's
format=fullmay return body.data with content already decoded from its original transfer encoding, but the CTE header still indicatesquoted-printable. The existing code would attempt to QP-decode again, causing:=characters (from URLs like?foo=bar) treated as invalid QP sequencesquotedprintable.Readerproduces U+FFFD for invalid sequencesSolution
Added
looksLikeQuotedPrintable()check (similar to existinglooksLikeBase64()) that detects actual QP markers before decoding:=\r\nor=\n)=XXwhere X is 0-9 or A-F)Using uppercase-only hex detection avoids false positives from URLs containing lowercase letters after
=(e.g.,?foo=bar).Testing
Added unit tests covering:
Contributed via OpenClaw agent — active gog CLI users contributing back.