fix(gmail): match message header names case-insensitively (#642)#869
fix(gmail): match message header names case-insensitively (#642)#869shigechika wants to merge 1 commit into
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parse_message_headers used exact-case string matching, so headers whose field names use non-canonical casing -- e.g. "CC" (common from Exchange/Outlook) or a lowercase "from" from some MTAs -- fell through and were silently dropped. This dropped CC recipients from +reply-all. Per RFC 5322 1.2.2 header field names are case-insensitive, and the sibling get_part_header already uses eq_ignore_ascii_case. Normalize the name to lowercase before matching, and add a regression test covering mixed-case FROM/to/CC/Reply-TO/subject/MESSAGE-ID/References. Fixes googleworkspace#642. Claude-Session: https://claude.ai/code/session_01EuRYoXhx7ozQWx19mAFLUS
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Summary of ChangesHello, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed! This pull request addresses an issue where email headers with non-canonical casing were being silently dropped, causing problems with features like reply-all. By normalizing header names to lowercase, the implementation now correctly handles headers regardless of their original casing, as per RFC 5322 standards. Highlights
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Code Review
This pull request fixes an issue where Gmail message headers were matched case-sensitively, causing headers with non-canonical casing (such as uppercase "CC") to be silently dropped. The fix normalizes header names to lowercase before matching and adds a corresponding regression test. The review feedback points out that using to_ascii_lowercase() inside the loop allocates a new String on the heap for every header parsed, and suggests using eq_ignore_ascii_case in an if/else if chain to avoid these allocations.
| match name.to_ascii_lowercase().as_str() { | ||
| "from" => parsed.from = value.to_string(), | ||
| "reply-to" => append_address_list_header_value(&mut parsed.reply_to, value), | ||
| "to" => append_address_list_header_value(&mut parsed.to, value), | ||
| "cc" => append_address_list_header_value(&mut parsed.cc, value), | ||
| "subject" => parsed.subject = value.to_string(), | ||
| "date" => parsed.date = value.to_string(), | ||
| "message-id" => parsed.message_id = value.to_string(), | ||
| "references" => append_header_value(&mut parsed.references, value), | ||
| _ => {} | ||
| } |
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Using name.to_ascii_lowercase() inside the loop allocates a new String on the heap for every single header parsed. This can be avoided entirely by using eq_ignore_ascii_case in an if/else if chain, which performs case-insensitive comparison without any allocations.
if name.eq_ignore_ascii_case("From") {
parsed.from = value.to_string();
} else if name.eq_ignore_ascii_case("Reply-To") {
append_address_list_header_value(&mut parsed.reply_to, value);
} else if name.eq_ignore_ascii_case("To") {
append_address_list_header_value(&mut parsed.to, value);
} else if name.eq_ignore_ascii_case("Cc") {
append_address_list_header_value(&mut parsed.cc, value);
} else if name.eq_ignore_ascii_case("Subject") {
parsed.subject = value.to_string();
} else if name.eq_ignore_ascii_case("Date") {
parsed.date = value.to_string();
} else if name.eq_ignore_ascii_case("Message-ID") {
parsed.message_id = value.to_string();
} else if name.eq_ignore_ascii_case("References") {
append_header_value(&mut parsed.references, value);
}2 participants
Re-opening #847, which the stale bot auto-closed after 72h of inactivity before a maintainer could review it. No code changes since #847 — same fix, still needed (upstream/main still has the case-sensitive match as of this comment).
Summary
parse_message_headersmatched header names with exact-case string comparison, so headers whose field names use non-canonical casing — e.g."CC"(common from Exchange/Outlook) or a lowercase"from"from some MTAs — fell through and were silently dropped. This dropped CC recipients from+reply-all. Per RFC 5322 §1.2.2 header field names are case-insensitive (the siblingget_part_headeralready useseq_ignore_ascii_case). Normalize the name to lowercase before matching.Fixes #642.