fix: normalizeHeaders throws on flat header arrays from dns re-dispatch#5535
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GiHoon1123 wants to merge 1 commit into
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fix: normalizeHeaders throws on flat header arrays from dns re-dispatch#5535GiHoon1123 wants to merge 1 commit into
GiHoon1123 wants to merge 1 commit into
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normalizeHeaders() in lib/util/cache.js (shared by the cache and deduplicate interceptors) only recognized headers as a plain object or an iterable of [key, value] pairs. It didn't recognize the flat, alternating [key, value, key, value, ...] array that the dns interceptor's withHostHeader() produces when it re-dispatches after resolving an address -- the same low-level shape core/util.js and dispatcher/client-h1.js already consume. Because compose() wraps arguments innermost-first, .compose(cache(), dns()) makes dns the outer interceptor and cache its "next", so dns's post-resolution re-dispatch lands back in cache's normalizeHeaders() with headers already in that shape, misread as a broken pairs array. Detect the flat-array shape by checking whether the first element is itself an array. Also widened the value check (both the new branch and the existing pairs branch) to accept string[] as well as string, matching what client-h1.js already accepts for repeated headers like Set-Cookie -- the stricter string-only check would have thrown again on that case.
mcollina
reviewed
Jul 9, 2026
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use a proper for loop, .every() is slow.
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #5535 +/- ##
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Coverage 93.44% 93.45%
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Files 110 110
Lines 37329 37352 +23
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+ Hits 34883 34908 +25
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This relates to...
Fixes #5522
Rationale
normalizeHeaders()inlib/util/cache.js(shared by thecacheanddeduplicateinterceptors) only recognized headers as a plain object or an iterable of[key, value]pairs. It didn't recognize the flat, alternating[key, value, key, value, ...]array that thednsinterceptor'swithHostHeader()produces when it re-dispatches after resolving an address -- the same low-level shapecore/util.jsanddispatcher/client-h1.jsalready consume on the way to the wire.Because
compose()wraps arguments innermost-first,.compose(cache(), dns())makesdnsthe outer interceptor andcacheits "next" -- sodns's post-resolution re-dispatch lands back incache's (ordeduplicate's)normalizeHeaders()with headers already in that shape, which got misread as a malformed pairs array and threw.Changes
normalizeHeaders(): detect the flat-array shape (first element is not itself an array) before falling through to the existing pairs-array handling.string[]as well asstring, matching whatclient-h1.jsalready accepts for repeated headers likeSet-Cookie-- a plain string-only check would have thrown again on that case.normalizeHeaders's JSDoc@param/@returnsto reference the actual accepted input (DispatchOptions, whose.headersisUndiciHeaders-- already covers object/array/iterable) instead of the staleRecord<string, string[] | string>.normalizeHeadersdirectly (test/cache-interceptor/cache-utils.js): flat array, empty flat array, flat array with an array value, tuple-style array with an array value, and two invalid-value cases that should still throw.test/interceptors/dns.jsreproducing the exactdns -> cacheanddns -> deduplicatere-dispatch path with a local server and mockedlookup(no real DNS/network needed).Features
N/A
Bug Fixes
normalizeHeadersfails withopts.headers is not a valid header mapdepending on interceptor ordering #5522 (Error: opts.headers is not a valid header map) when composing thecacheordeduplicateinterceptor "after"dns(e.g..compose(cache(), dns())).Breaking Changes and Deprecations
N/A -- this only widens what
normalizeHeaders()accepts; nothing that previously worked changes shape or behavior.Status