wehub-resource-sync
48 lines
1.6 KiB
TypeScript
48 lines
1.6 KiB
TypeScript
/**
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* Header-strip helper for upstream provider responses.
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*
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* `fetch()` always decompresses the upstream body before exposing it via
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* `.text()` or the stream reader, so forwarding the upstream `content-encoding`
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* to the downstream client (e.g. `gzip`) makes the client attempt to gunzip
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* plain text and fail with `ZlibError: incorrect header check`.
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*
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* Similarly, `content-length` becomes stale once we transform or repack the
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* response stream, and `transfer-encoding` is managed by the runtime
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* (Next.js / Node), not us.
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*/
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const STRIP_HEADER_NAMES: ReadonlySet<string> = new Set([
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"content-encoding",
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"content-length",
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"transfer-encoding",
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]);
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/**
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* Return a new `Headers` instance with stale encoding/length headers removed.
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* Does not mutate the input.
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*/
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export function stripStaleEncodingHeaders(input: Headers): Headers {
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const out = new Headers(input);
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for (const name of STRIP_HEADER_NAMES) out.delete(name);
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return out;
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}
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/**
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* Return a new entries array with stale encoding/length headers removed and
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* (optionally) additional header names removed. Case-insensitive.
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*/
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export function filterUpstreamResponseHeaderEntries(
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entries: Iterable<[string, string]>,
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extraToStrip: ReadonlyArray<string> = []
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): Array<[string, string]> {
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const drop = new Set<string>(STRIP_HEADER_NAMES);
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for (const h of extraToStrip) drop.add(h.toLowerCase());
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const result: Array<[string, string]> = [];
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for (const [k, v] of entries) {
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if (!drop.has(k.toLowerCase())) result.push([k, v]);
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}
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return result;
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}
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export const STRIP_UPSTREAM_HEADER_NAMES: ReadonlySet<string> = STRIP_HEADER_NAMES;
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