fix caching of not understod statuses

finish fixing #4334

Author: fredericDelaporte

lib/handler/cache-handler.js

@@ -15,6 +15,15 @@ const HEURISTICALLY_CACHEABLE_STATUS_CODES = [
   200, 203, 204, 206, 300, 301, 308, 404, 405, 410, 414, 501
 ]
 
+// Status codes which semantic is not handled by the cache
+// https://datatracker.ietf.org/doc/html/rfc9111#section-3
+// This list should not grow beyond 206 and 304 unless the RFC is updated
+// by a newer one including more. Please introduce another list if
+// implementing caching of responses with the 'must-understand' directive.
+const NOT_UNDERSTOOD_STATUS_CODES = [
+  206, 304
+]
+
 const MAX_RESPONSE_AGE = 2147483647000
 
 /**
@@ -241,8 +250,8 @@ class CacheHandler {
  * @param {import('../../types/cache-interceptor.d.ts').default.CacheControlDirectives} cacheControlDirectives
  */
 function canCacheResponse (cacheType, statusCode, resHeaders, cacheControlDirectives) {
-  // Status code must be final.
-  if (statusCode < 200) {
+  // Status code must be final and understood.
+  if (statusCode < 200 || NOT_UNDERSTOOD_STATUS_CODES.includes(statusCode)) {
     return false
   }
   // Responses with neither status codes that are heuristically cacheable, nor explicit caching directives,

test/interceptors/cache.js

@@ -1543,4 +1543,114 @@ describe('Cache Interceptor', () => {
       }
     })
   }
+
+  test('discriminates caching of range requests, or does not cache them', async () => {
+    let requestsToOrigin = 0
+    const body = 'Fake range request response'
+    const code = 206
+    const server = createServer({ joinDuplicateHeaders: true }, (_, res) => {
+      requestsToOrigin++
+      res.statusCode = code
+      res.setHeader('cache-control', 'public, max-age=60')
+      res.end(body)
+    }).listen(0)
+
+    const client = new Client(`http://localhost:${server.address().port}`)
+      .compose(interceptors.cache())
+
+    after(async () => {
+      server.close()
+      await client.close()
+    })
+
+    await once(server, 'listening')
+
+    equal(requestsToOrigin, 0)
+
+    const request = {
+      origin: 'localhost',
+      method: 'GET',
+      path: '/',
+      headers: {
+        range: 'bytes=10-'
+      }
+    }
+
+    // First request should hit the origin
+    {
+      const res = await client.request(request)
+      equal(requestsToOrigin, 1)
+      equal(res.statusCode, code)
+      strictEqual(await res.body.text(), body)
+    }
+
+    // Second request with different range should hit the origin too
+    request.headers.range = 'bytes=5-'
+    {
+      const res = await client.request(request)
+      equal(requestsToOrigin, 2)
+      equal(res.statusCode, code)
+      strictEqual(await res.body.text(), body)
+    }
+  })
+
+  test('discriminates caching of conditionnal requests, or does not cache them', async () => {
+    let requestsToOrigin = 0
+    const body = ''
+    const code = 304
+    const server = createServer({ joinDuplicateHeaders: true }, (_, res) => {
+      requestsToOrigin++
+      res.statusCode = code
+      res.setHeader('cache-control', 'public, max-age=60')
+      res.end(body)
+    }).listen(0)
+
+    const client = new Client(`http://localhost:${server.address().port}`)
+      .compose(interceptors.cache())
+
+    after(async () => {
+      server.close()
+      await client.close()
+    })
+
+    await once(server, 'listening')
+
+    equal(requestsToOrigin, 0)
+
+    const request = {
+      origin: 'localhost',
+      method: 'GET',
+      path: '/',
+      headers: {
+        'if-modified-since': new Date().toUTCString(),
+        'if-none-match': 'some-etag'
+      }
+    }
+
+    // First request should hit the origin
+    {
+      const res = await client.request(request)
+      equal(requestsToOrigin, 1)
+      equal(res.statusCode, code)
+      strictEqual(await res.body.text(), body)
+    }
+
+    // Second request with different etag should hit the origin too
+    request.headers['if-none-match'] = 'another-etag'
+    {
+      const res = await client.request(request)
+      equal(requestsToOrigin, 2)
+      equal(res.statusCode, code)
+      strictEqual(await res.body.text(), body)
+    }
+
+    // Third request with different since should hit the origin too
+    request.headers['if-modified-since'] = new Date(0).toUTCString()
+    {
+      const res = await client.request(request)
+      equal(requestsToOrigin, 3)
+      equal(res.statusCode, code)
+      strictEqual(await res.body.text(), body)
+    }
+  })
 })