Description

The parseCacheControlDirectives function did not handle quoted-string values per RFC 9111 Section 5.2 / RFC 9110 Section 5.6.4. Directives like community="UCI" were parsed with quotes included in the value ("UCI" instead of UCI). While current directives (max-age, s-maxage, etc.) use token values, proper quoted-string support ensures RFC compliance and future-proofs the parser.

Changes introduced

Implementation:

• Enhanced parseCacheControlDirectives to detect and unquote quoted-string directive values
• Added unquoteCacheDirective helper that removes surrounding quotes and processes backslash-escapes
• Fixed key trimming to handle spaces around = delimiter

Testing:

• Test_parseCacheControlDirectives_QuotedStrings: 10 test cases covering quoted values, mixed directives, escaped characters
• Test_unquoteCacheDirective: 9 test cases for unquoting logic including edge cases

Examples:

// Before: quotes included in parsed value
parseCacheControlDirectives([]byte(`community="UCI"`), func(key, value []byte) {
    // value = []byte(`"UCI"`)  // incorrect
})

// After: quotes properly removed
parseCacheControlDirectives([]byte(`community="UCI"`), func(key, value []byte) {
    // value = []byte(`UCI`)  // correct
})

// Escaped characters handled correctly
parseCacheControlDirectives([]byte(`custom="value with \"quotes\""`), func(key, value []byte) {
    // value = []byte(`value with "quotes"`)
})

// Token values (existing behavior) unchanged
parseCacheControlDirectives([]byte(`max-age=3600`), func(key, value []byte) {
    // value = []byte(`3600`)  // works as before
})

• Documentation Update: N/A - internal parser function
• Changelog/What's New: RFC 9111 compliant quoted-string parsing for Cache-Control
• API Longevity: Maintains full backward compatibility; all existing tests pass
• Examples: See code examples above

Type of change

• Code consistency (non-breaking change which improves code reliability and robustness)

Checklist

• Conducted a self-review of the code and provided comments for complex or critical parts.
• Added or updated unit tests to validate the effectiveness of the changes or new features.
• Ensured that new and existing unit tests pass locally with the changes.
• Aimed for optimal performance with minimal allocations in the new code.

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