gh-128110: Fix rfc2047 handling in email parser address headers by medmunds · Pull Request #130749 · python/cpython
RFC 2047 Section 6.2 requires that "any 'linear-white-space' that separates a pair of adjacent 'encoded-word's is ignored." The modern header value parser correctly implements that for unstructured headers, but had missed a case in structured headers. This could cause a parsed address header to include extraneous spaces in a display-name. Fixed in get_atom() by converting a trailing CFWSList token after an encoded-word to an EWWhiteSpaceTerminal if another encoded-word follows. Deliberately left similar code in get_dotatom() unmodified. A dotatom can only appear within an addr-spec. RFC 2047 Section 5 prohibits use of an encoded-word in any portion of an addr-spec, so its appearance in a dotatom is invalid. Adding (and testing) special white-space handling in an invalid dotatom seems an unnecessary complication.
Switch to @bitdancer's fix from review feedback. Recharacterize space between ews as fws after parsing in get_phrase (rather than peeking ahead after first ew in get_word). Co-authored-by: R David Murray <rdmurray@bitdance.com>
bitdancer added a commit that referenced this pull request
…ress headers (GH-130749) (#149787) RFC 2047 Section 6.2 requires that "any 'linear-white-space' that separates a pair of adjacent 'encoded-word's is ignored." The modern header value parser correctly implements that for unstructured headers, but had missed a case in structured headers. This could cause a parsed address header to include extraneous spaces in a display-name. Switch to @bitdancer's fix from review feedback. Recharacterize space between ews as fws after parsing in get_phrase. RDM: This fix is dependent on the fact that "subsequent" atoms will never have leading whitespace because that's been consumed already. I don't think it's worth adding extra code for the possibility of leading whitespace because the parser won't produce it. It's a bit of parser fragility in the face of code changes, but I think that's a minor concern given the parser design (which is that it consumes whitespace greedily) (cherry picked from commit 7a4c6df) Co-authored-by: Mike Edmunds <medmunds@gmail.com> Co-authored-by: R David Murray <rdmurray@bitdance.com>
bitdancer added a commit that referenced this pull request
…ress headers (GH-130749) (#149788) RFC 2047 Section 6.2 requires that "any 'linear-white-space' that separates a pair of adjacent 'encoded-word's is ignored." The modern header value parser correctly implements that for unstructured headers, but had missed a case in structured headers. This could cause a parsed address header to include extraneous spaces in a display-name. Switch to @bitdancer's fix from review feedback. Recharacterize space between ews as fws after parsing in get_phrase. RDM: This fix is dependent on the fact that "subsequent" atoms will never have leading whitespace because that's been consumed already. I don't think it's worth adding extra code for the possibility of leading whitespace because the parser won't produce it. It's a bit of parser fragility in the face of code changes, but I think that's a minor concern given the parser design (which is that it consumes whitespace greedily) (cherry picked from commit 7a4c6df) Co-authored-by: Mike Edmunds <medmunds@gmail.com> Co-authored-by: R David Murray <rdmurray@bitdance.com>
bitdancer added a commit that referenced this pull request
…ress headers (GH-130749) (#149789) RFC 2047 Section 6.2 requires that "any 'linear-white-space' that separates a pair of adjacent 'encoded-word's is ignored." The modern header value parser correctly implements that for unstructured headers, but had missed a case in structured headers. This could cause a parsed address header to include extraneous spaces in a display-name. Switch to @bitdancer's fix from review feedback. Recharacterize space between ews as fws after parsing in get_phrase. RDM: This fix is dependent on the fact that "subsequent" atoms will never have leading whitespace because that's been consumed already. I don't think it's worth adding extra code for the possibility of leading whitespace because the parser won't produce it. It's a bit of parser fragility in the face of code changes, but I think that's a minor concern given the parser design (which is that it consumes whitespace greedily) (cherry picked from commit 7a4c6df) Co-authored-by: Mike Edmunds <medmunds@gmail.com> Co-authored-by: R David Murray <rdmurray@bitdance.com>
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