Build the well-known-string table at compile time

[moonchen]

hdrtoken_init() builds the well-known-string (WKS) table at startup. This PR does the work at compile-time, which enables more robust checking, and removes an old restriction regarding prefixes.

1. Modernize the well-known-string initialization

Make use of constexpr to initialize WKS at compile time. Remove the unnecessary name field from the WKS table at runtime. Trim the hdrtoken_hash_table size to just the reachable number of slots, build it at compile time as well, and shrink its buckets from 16 to 8 bytes by storing an index instead of a pointer.

	before	after
WKS table	~15 KB on the heap	10,800 B in .rodata
hdrtoken_hash_table	1,052,904 B	262,144 B in .rodata
sizeof(HdrTokenHeapPrefix)	56	48

2. Add compile-time checks for WKS correctness

Checks are now done at compile-time, and the new checks are more strict than the old release asserts.

An append-only ledger (_hdrtoken_strs_frozen) fingerprints the frozen entries: inserting, reordering, or editing them fails to compile, and appending strings requires appending a matching ledger row.

3. Remove the restriction that prevents a WKS from being added after its prefix

In order to maintain cache compatibility, new strings needed to be appended to the list. Previously, it was not legal to append a string to WKS if its prefix already exists.

This PR removes the prefix restriction. We can now append strings like Server-Timing, Accept-CH, and Expect-CT.

[moonchen]

[approve ci Autest 1]

[moonchen]

[approve ci autest 1]

[Copilot]

Pull request overview

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Moves well-known-string (WKS) construction from runtime to compile time using constexpr, enabling stronger correctness checks and reducing startup work / memory overhead.

Changes:

• Build the WKS table at compile time and populate runtime “hot” parallel arrays from it during hdrtoken_init().
• Add compile-time validation (initializer/name resolution, hash-slot uniqueness) and shrink the hash table to the reachable slot space.
• Relocate Cache-Control cooked-mask bindings into WKS initialization and remove the MIME startup hook.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
src/proxy/hdrs/MIME.cc	Removes runtime Cache-Control mask initialization; updates WKS/prefix access to const.
src/proxy/hdrs/HdrToken.cc	Introduces compile-time WKS table build + checks; updates hashing/slot sizing; keeps runtime init lightweight.
include/proxy/hdrs/MIME.h	Removes declaration of the deleted Cache-Control init hook.
include/proxy/hdrs/HdrToken.h	Updates field initializer types and makes WKS prefix access read-only (const).

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

Suppressed comments (2)

src/proxy/hdrs/HdrToken.cc:354

• This fingerprint uses the case-folding token hash, so it does not actually detect every edit that the frozen ledger promises to reject. For example, changing the frozen method GET to get leaves this fingerprint unchanged, but then hdrtoken_method_tokenize() rejects GET and accepts get. Hash the original bytes (without hdrtoken_ascii_toupper) for the ledger; token lookup can remain case-insensitive.

    for (char const c : _hdrtoken_strs[i]) {
      hval = hdrtoken_hash_step(hval, static_cast<unsigned char>(c));
    }
    hval = hdrtoken_hash_step(hval, '\0'); // fold in a terminator so entry boundaries matter

src/proxy/hdrs/HdrToken.cc:624

• These range endpoints no longer belong to one character array: every HdrTokenWksEntry::str is a distinct array subobject. hdrtoken_is_wks() still classifies pointers with built-in >=/<=, whose ordering is unspecified across these subarrays, so a valid WKS pointer from an intermediate entry is not portably guaranteed to fall between these endpoints. Represent and compare the bounds as uintptr_t values (consistent with hdrtoken_wks_to_prefix()), or otherwise use a defined total pointer ordering.

const char *_hdrtoken_strs_heap_f = &hdrtoken_wks_table[0].str[0]; // storage first byte
const char *_hdrtoken_strs_heap_l = &hdrtoken_wks_table[std::size(_hdrtoken_strs) - 1].str[HDRTOKEN_WKS_STORAGE - 1];

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.