cache-control: no-cache: use quoted-string form

[alxndrsn]

Update comment example of qualified no-cache directives (no-cache=...) to use the quoted-string form instead of the token form.

Per https://datatracker.ietf.org/doc/html/rfc9111#name-no-cache-2:

This directive uses the quoted-string form of the argument syntax. A sender SHOULD NOT generate the token form (even if quoting appears not to be needed for single-entry lists).

This relates to...

cache-control response header's qualified no-cache directive.

Rationale

Seems more correct to follow spec recommendations in documentation.

Support for token form seems to be deliberate:

undici/test/cache-interceptor/utils.js

Lines 68 to 96 in 0daba93

	test('no-cache with headers', () => {
	let directives = parseCacheControlHeader('max-age=10, no-cache=some-header, only-if-cached')
	deepStrictEqual(directives, {
	'max-age': 10,
	'no-cache': [
	'some-header'
	],
	'only-if-cached': true
	})
	directives = parseCacheControlHeader('max-age=10, no-cache="some-header", only-if-cached')
	deepStrictEqual(directives, {
	'max-age': 10,
	'no-cache': [
	'some-header'
	],
	'only-if-cached': true
	})
	directives = parseCacheControlHeader('max-age=10, no-cache="some-header, another-one", only-if-cached')
	deepStrictEqual(directives, {
	'max-age': 10,
	'no-cache': [
	'some-header',
	'another-one'
	],
	'only-if-cached': true
	})
	})

Changes

Update comment and test examples of qualified no-cache directives (no-cache=...) to use the quoted-string form instead of the token form.

Features

N/A

Bug Fixes

N/A

Breaking Changes and Deprecations

Should not break anything, as no code changed.

Status

• I have read and agreed to the Developer's Certificate of Origin
• Tested
• [S] Benchmarked (optional)
• Documented
• Review ready
• In review
• Merge ready

[alxndrsn]

The no-cache=... parsing code seems to go out of its way to support various different token or mixed token/quoted-string formats:

undici/test/cache-interceptor/utils.js

Lines 68 to 96 in 0daba93

	test('no-cache with headers', () => {
	let directives = parseCacheControlHeader('max-age=10, no-cache=some-header, only-if-cached')
	deepStrictEqual(directives, {
	'max-age': 10,
	'no-cache': [
	'some-header'
	],
	'only-if-cached': true
	})
	directives = parseCacheControlHeader('max-age=10, no-cache="some-header", only-if-cached')
	deepStrictEqual(directives, {
	'max-age': 10,
	'no-cache': [
	'some-header'
	],
	'only-if-cached': true
	})
	directives = parseCacheControlHeader('max-age=10, no-cache="some-header, another-one", only-if-cached')
	deepStrictEqual(directives, {
	'max-age': 10,
	'no-cache': [
	'some-header',
	'another-one'
	],
	'only-if-cached': true
	})
	})

Would it be better to only allow quote-string format?

[mcollina]

Would it be better to only allow quote-string format?

@flakey5 was this due to the compatibility tests?

[flakey5]

@flakey5 was this due to the compatibility tests?

Yes. If this isn't wanted behavior, the test cases for it in the caching suite will need to be added to the ignoredTests list in test/cache-interceptor/cache-tests.mjs