constrained identity function

sveltejs · Aug 20, 2021 · 66f7915 · 66f7915
1 parent 5f83e8a
commit 66f7915
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Showing 4 changed files with 33 additions and 6 deletions.
diff --git a/packages/kit/src/core/adapt/prerender.js b/packages/kit/src/core/adapt/prerender.js
@@ -4,6 +4,7 @@ import { pathToFileURL, resolve, URL } from 'url';
 import { mkdirp } from '../../utils/filesystem.js';
 import { __fetch_polyfill } from '../../install-fetch.js';
 import { SVELTE_KIT } from '../constants.js';
+import { get_single_valued_header } from '../../utils/http.js';
 
 /**
  * @typedef {import('types/config').PrerenderErrorHandler} PrerenderErrorHandler
@@ -182,10 +183,14 @@ export async function prerender({ cwd, out, log, config, build_data, fallback, a
 			mkdirp(dirname(file));
 
 			if (response_type === REDIRECT) {
-				const location = /** @type {string} */ (headers.location);
+				const location = get_single_valued_header(headers, 'location');
 
-				log.warn(`${rendered.status} ${path} -> ${location}`);
-				writeFileSync(file, `<meta http-equiv="refresh" content="0;url=${encodeURI(location)}">`);
+				if (location) {
+					log.warn(`${rendered.status} ${path} -> ${location}`);
+					writeFileSync(file, `<meta http-equiv="refresh" content="0;url=${encodeURI(location)}">`);
+				} else {
+					log.warn(`location header missing on redirect received from ${path}`);
+				}
 
 				return;
 			}

diff --git a/packages/kit/src/runtime/server/endpoint.js b/packages/kit/src/runtime/server/endpoint.js
@@ -1,3 +1,4 @@
+import { get_single_valued_header } from '../../utils/http.js';
 import { lowercase_keys } from './utils.js';
 
 /** @param {string} body */
@@ -62,7 +63,7 @@ export async function render_endpoint(request, route, match) {
 	let { status = 200, body, headers = {} } = response;
 
 	headers = lowercase_keys(headers);
-	const type = /** @type {string} */ (headers['content-type']);
+	const type = get_single_valued_header(headers, 'content-type');
 
 	const is_type_textual = is_content_type_textual(type);
 

diff --git a/packages/kit/src/runtime/server/index.js b/packages/kit/src/runtime/server/index.js
@@ -6,6 +6,7 @@ import { parse_body } from './parse_body/index.js';
 import { lowercase_keys } from './utils.js';
 import { coalesce_to_error } from '../utils.js';
 import { hash } from '../hash.js';
+import { get_single_valued_header } from '../../utils/http.js';
 
 /**
  * @param {import('types/internal').Incoming} incoming
@@ -70,8 +71,8 @@ export async function respond(incoming, options, state = {}) {
 					if (response) {
 						// inject ETags for 200 responses
 						if (response.status === 200) {
-							const cache_control = /** @type {string} */ (response.headers['cache-control']);
-							if (!/(no-store|immutable)/.test(cache_control)) {
+							const cache_control = get_single_valued_header(response.headers, 'cache-control');
+							if (!cache_control || !/(no-store|immutable)/.test(cache_control)) {
 								const etag = `"${hash(response.body || '')}"`;
 
 								if (request.headers['if-none-match'] === etag) {

diff --git a/packages/kit/src/utils/http.js b/packages/kit/src/utils/http.js
@@ -0,0 +1,20 @@
+/**
+ * @param {Record<string,string|string[]>} headers
+ * @param {string} key
+ * @returns {string|undefined}
+ */
+export function get_single_valued_header(headers, key) {
+	const value = headers[key];
+	if (Array.isArray(value)) {
+		if (value.length === 0) {
+			return undefined;
+		}
+		if (value.length > 1) {
+			throw new Error(
+				`Multiple headers provided for ${key}. Multiple may be provided only for set-cookie`
+			);
+		}
+		return value[0];
+	}
+	return value;
+}