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Kévin DunglasandKağan Küçük
857d5731f3
* perf: bypass header key normalization for canonical literals
http.Header's Get, Set, Add and Del run textproto.CanonicalMIMEHeaderKey
on every call. When the key is a canonical literal the result is the key
itself, so the scan is pure overhead. Access the map directly instead.
Only hot, allocation-free paths are converted, and only where the key is
a canonical literal. Call sites taking a key from config, a template or
the request itself still go through the normalizing methods, since they
need it for correctness.
allHeaderValues and lastHeaderValue dropped their http.CanonicalHeaderKey
call for the same reason: all callers pass canonical literals.
benchstat, Apple M5 Pro, go1.27.1:
PrepareRequest-15 659.4n ± 2% -> 457.7n ± 2% -30.58% (p=0.000 n=12)
AcceptedEncodings-15 330.8n ± 5% -> 309.4n ± 7% -6.44% (p=0.019 n=10)
ResponseWriterWriteHeader/event-stream-15 1007.5n ± 3% -> 732.5n ± 1% -27.30%
ResponseWriterWriteHeader/informational-15 60.0n ± 3% -> 48.0n ± 2% -20.01%
ResponseWriterWriteHeader/not-modified-15 214.3n ± 6% -> 175.3n ± 4% -18.20%
ResponseWriterWriteHeader/connect-15 60.2n ± 3% -> 51.9n ± 4% -13.85%
ResponseWriterWriteHeader/html-15 206.5n ± 4% -> 197.9n ± 2% -4.19%
geomean -14.38%
Allocations are unchanged.
* tests: verify http.Header map keys are canonical
Indexing http.Header directly skips the canonicalization Get/Set/Add/Del
perform, which also puts the key outside what CI checks. canonicalheader
only inspects method calls. staticcheck's SA1008 covers reads, but stops
descending as soon as an assignment writes to a header, so it misses the
write, the delete builtin and the read-modify-write append. A key that is
not canonical in those positions is a silent lookup miss, not a compile
error.
Walk the loaded packages and verify every string constant used as a key in
an http.Header map operation matches http.CanonicalHeaderKey. A helper that
takes the key from its caller would hide the literal again, so a parameter
named with a canonical prefix opts its arguments into the same check.
The WebSocket headers Caddy deliberately writes with RFC 6455 casing are
allowed explicitly; they are only ever written out, never looked up against
a parsed header map.
Covers 64 operations, runs in under a second, and promotes golang.org/x/tools
from an indirect to a direct dependency at the version already in the module
graph.
* headercheck: resolve aliases of http.Header
* headercheck: check http.Header composite literal keys
* headercheck: note overlap with canonicalheader
* headercheck: drop parameter-name check
Helpers now take the indexed values, so every key sits in an index expression the analyzer and the linter already check.
* headercheck: scope RFC 6455 exceptions to their call sites
A key-based allow-list also accepted reads such as h["Sec-WebSocket-Key"], which miss because parsed headers are canonical. Honor //nolint:canonicalheader on the line instead, which the linter will use too.
* encode: read every Accept-Encoding field line
AcceptedEncodings read only the first field line, so a client that split
the list across several lines had the rest ignored. RFC 9110 section 5.3
treats repeated list-field lines as one comma-joined list. Iterate over
the items of every line instead of joining them, and skip empty items,
which used to yield an empty encoding. file_server's precompressed
selection uses the same function and is fixed with it.
Fixes https://github.com/caddyserver/caddy/issues/8272
Co-authored-by: Kağan Küçük <kaankck@gmail.com>
* encode: read every Cache-Control and Content-Encoding field line
Only the first field line was read, but RFC 9110 section 5.3 makes
multiple lines of a list-based field equivalent to one comma-joined
value:
- Cache-Control: no-transform on a later line was ignored, so the
request or response was compressed anyway.
- Content-Encoding: an empty first line followed by a real coding let
the handler encode the body a second time.
* encode: parse Cache-Control no-transform per RFC 9111
The substring match missed No-Transform, though RFC 9111 section 5.2 compares directive names case-insensitively, and fired on text that is not the directive: longer tokens such as x-no-transform-ext, quoted arguments such as community="no-transform", and semicolon-separated values, which are not valid Cache-Control syntax. Split the field on commas outside quoted strings and match only a well-formed no-transform element.
* encode: keep accepted encoding preferences on the stack
AcceptedEncodings counted commas to size the preference slice, and the variable capacity put it on the heap. A constant capacity covers typical Accept-Encoding headers and lets the compiler keep the slice on the stack; append still moves it to the heap for longer ones. BenchmarkAcceptedEncodings: 151.8ns -> 120.5ns (-21%), 192 -> 64 B/op, 2 -> 1 allocs/op (n=8).
* encode: build the encoded ETag without fmt
fmt.Sprintf boxed both arguments and parsed the format on every encoded response with a strong ETag. Concatenation: 47ns -> 16.5ns, 56 -> 24 B, 3 -> 1 allocs.
* reverseproxy: access response Server and Via headers directly
finalizeResponse runs on every proxied response; skip the key normalization as prepareRequest already does on the request side.
* encode: access headers directly in Write, WriteHeader and Close
These run once per response; convert the remaining literal-key Get, Set and Add calls like the rest of the handler.
* encode: match Cache-Control no-transform with httpguts
httpguts.HeaderValuesContainsToken already compares list elements case-insensitively across field lines, so the hand-written list parser is unnecessary. A no-transform inside a comma-separated quoted argument now also disables encoding, which only errs toward not transforming.
* encode: inline the no-transform check
isEncodeAllowed only wrapped one httpguts call. Its unit test now drives the response directive through ServeHTTP instead.
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Co-authored-by: Kağan Küçük <kaankck@gmail.com>