feat: fallback from flat file origins

src/client.js

@@ -261,9 +261,10 @@ export class Saturn {
       throw new Error(`All attempts to fetch content have failed. Last error: ${lastError.message}`)
     }
 
-    const fetchContent = async function * () {
+    const fetchContent = async function * (options) {
       let byteCount = 0
-      const byteChunks = await this.fetchContent(cidPath, opts)
+      const fetchOptions = Object.assign(opts, options)
+      const byteChunks = await this.fetchContent(cidPath, fetchOptions)
       for await (const chunk of byteChunks) {
         // avoid sending duplicate chunks
         if (byteCount < byteCountCheckpoint) {
@@ -327,7 +328,7 @@ export class Saturn {
       if (originUrl) {
         opts.nodes = Array({ url: originUrl })
         try {
-          yield * fetchContent()
+          yield * fetchContent({ flatFile: true })
           return
         } catch (err) {
           lastError = err
@@ -343,6 +344,7 @@ export class Saturn {
    * @param {object} [opts={}]
    * @param {('car'|'raw')} [opts.format]
    * @param {boolean} [opts.raceNodes]
+   * @param {boolean}  [opts.flatFile]
    * @param {number} [opts.connectTimeout=5000]
    * @param {number} [opts.downloadTimeout=0]
    * @returns {Promise<AsyncIterable<Uint8Array>>}
@@ -367,7 +369,11 @@ export class Saturn {
 
     try {
       const itr = metricsIterable(asAsyncIterable(res.body))
-      yield * extractVerifiedContent(cidPath, itr)
+      if (opts.flatFile) {
+        yield * itr
+      } else {
+        yield * extractVerifiedContent(cidPath, itr)
+      }
     } catch (err) {
       log.error = err.message
       controller.abort()

test/fallback.spec.js

@@ -3,7 +3,7 @@ import assert from 'node:assert/strict'
 import { describe, mock, test } from 'node:test'
 
 import { Saturn } from '#src/index.js'
-import { concatChunks, generateNodes, getMockServer, HTTP_STATUS_GONE, HTTP_STATUS_TIMEOUT, mockJWT, mockNodesHandlers, mockOrchHandler, mockOriginHandler, MSW_SERVER_OPTS } from './test-utils.js'
+import { concatChunks, generateNodes, getMockServer, HTTP_STATUS_GONE, HTTP_STATUS_TIMEOUT, mockFlatFileOriginHandler, mockJWT, mockNodesHandlers, mockOrchHandler, mockOriginHandler, MSW_SERVER_OPTS } from './test-utils.js'
 
 const TEST_DEFAULT_ORCH = 'https://orchestrator.strn.pl.test/nodes'
 const TEST_NODES_LIST_KEY = 'saturn-nodes'
@@ -280,7 +280,7 @@ describe('Client Fallback', () => {
       mockOrchHandler(numNodes, TEST_DEFAULT_ORCH, TEST_ORIGIN_DOMAIN),
       mockJWT(TEST_AUTH),
       mockOriginHandler(TEST_ORIGIN_DOMAIN, 0, true),
-      mockOriginHandler(TEST_CUSTOMER_ORIGIN, 0, false),
+      mockFlatFileOriginHandler(TEST_CUSTOMER_ORIGIN, 0, false),
       ...mockNodesHandlers(numNodes, TEST_ORIGIN_DOMAIN, numNodes, HTTP_STATUS_TIMEOUT)
     ]
 
@@ -303,9 +303,10 @@ describe('Client Fallback', () => {
 
     const buffer = await concatChunks(cid)
     const actualContent = String.fromCharCode(...buffer)
-    const expectedContent = 'hello world\n'
+    const jsonContent = JSON.parse(actualContent)
+    const expectedContent = JSON.parse('{ "hello": "world" }')
 
-    assert.strictEqual(actualContent, expectedContent)
+    assert.deepEqual(jsonContent, expectedContent)
     mock.reset()
     server.close()
   })

test/fixtures/hello.json

@@ -0,0 +1,3 @@
+{
+    "hello": "world"
+}

test/test-utils.js

@@ -68,6 +68,31 @@ export function mockOriginHandler (originUrl, delay = 0, error = false) {
   })
 }
 
+/**
+ * Generates a mock handler to mimick an origin that serves flat files.
+ *
+ * @param {string} originUrl - originUrl
+ * @param {number} delay - request delay in ms
+ * @param {boolean} error
+ * @returns {RestHandler<any>}
+ */
+export function mockFlatFileOriginHandler (originUrl, delay = 0, error = false) {
+  originUrl = addHttpPrefix(originUrl)
+  originUrl = `${originUrl}/ipfs/:cid`
+  return rest.get(originUrl, (req, res, ctx) => {
+    if (error) {
+      throw Error('Simulated Error')
+    }
+    const filepath = getFixturePath('hello.json')
+    const fileContents = fs.readFileSync(filepath)
+    return res(
+      ctx.delay(delay),
+      ctx.status(HTTP_STATUS_OK),
+      ctx.body(fileContents)
+    )
+  })
+}
+
 /**
  * Generates a mock handler to mimick Saturn's orchestrator /nodes endpoint.
  *