feat: add support for weak etag check

lib/handler/RetryHandler.js

@@ -70,7 +70,7 @@ class RetryHandler {
     this.retryAfter = null
     this.head = 0
     this.tail = null
-    this.etag = ''
+    this.etag = null
     this.resume = null
 
     // Handle possible onConnect duplication
@@ -183,14 +183,15 @@ class RetryHandler {
         return true
       }
 
-      // TODO (fix): etag
-      // if (this.etag == null || this.etag !== etag) {
-      //   throw this.error
-      // }
-
-      const contentRange = parseRangeHeader(headers['content-range'])
-      if (!contentRange) {
-        throw err
+      let contentRange
+      if (
+        // Let's start with a weak etag check
+        (this.etag != null && this.etag !== headers.etag) ||
+        // If no content range
+        !(contentRange = parseRangeHeader(headers['content-range']))
+      ) {
+        this.abort(err)
+        return false
       }
 
       const { start, size, end = size } = contentRange
@@ -245,6 +246,7 @@ class RetryHandler {
       )
 
       this.resume = resume
+      this.etag = headers.etag != null ? headers.etag : null
 
       return this.handler.onHeaders(
         statusCode,

test/retry-handler.js

@@ -6,9 +6,6 @@ const tap = require('tap')
 
 const { RetryHandler, Client } = require('..')
 
-// TODO: rewrite tests to not use explicit Promise handling
-// TODO: add tests for retry-after on 429
-
 tap.test('Should retry status code', t => {
   let counter = 0
   const chunks = []
@@ -663,3 +660,98 @@ tap.test('Should handle 206 partial content', t => {
     })
   })
 })
+tap.test('Should handle 206 partial content - bad-etag', { only: true }, t => {
+  const chunks = []
+
+  // Took from: https://github.com/nxtedition/nxt-lib/blob/4b001ebc2f22cf735a398f35ff800dd553fe5933/test/undici/retry.js#L47
+  let x = 0
+  const server = createServer((req, res) => {
+    if (x === 0) {
+      t.pass()
+      res.setHeader('etag', 'asd')
+      res.write('abc')
+      setTimeout(() => {
+        res.destroy()
+      }, 1e2)
+    } else if (x === 1) {
+      t.same(req.headers.range, 'bytes=3-')
+      res.setHeader('content-range', 'bytes 3-6/6')
+      res.setHeader('etag', 'erwsd')
+      res.statusCode = 206
+      res.end('def')
+    }
+    x++
+  })
+
+  const dispatchOptions = {
+    method: 'GET',
+    path: '/',
+    headers: {
+      'content-type': 'application/json'
+    }
+  }
+
+  t.plan(6)
+
+  server.listen(0, () => {
+    const client = new Client(`http://localhost:${server.address().port}`)
+    const handler = new RetryHandler(
+      dispatchOptions,
+      {
+        dispatch: (...args) => {
+          return client.dispatch(...args)
+        },
+        handler: {
+          onConnect () {
+            t.pass()
+          },
+          onBodySent () {
+            t.pass()
+          },
+          onHeaders (status, _rawHeaders, resume, _statusMessage) {
+            t.pass()
+            return true
+          },
+          onData (chunk) {
+            chunks.push(chunk)
+            return true
+          },
+          onComplete () {
+            t.error('should not complete')
+          },
+          onError (err) {
+            t.equal(Buffer.concat(chunks).toString('utf-8'), 'abc')
+            t.equal(err.code, 'UND_ERR_REQ_RETRY')
+          }
+        }
+      },
+      {
+        retry: function (err) {
+          if (err.code && err.code === 'UND_ERR_DESTROYED') {
+            return null
+          }
+
+          return err.statusCode === 206 ? null : 800
+        }
+      }
+    )
+
+    client.dispatch(
+      {
+        method: 'GET',
+        path: '/',
+        headers: {
+          'content-type': 'application/json'
+        }
+      },
+      handler
+    )
+
+    t.teardown(async () => {
+      await client.close()
+
+      server.close()
+      await once(server, 'close')
+    })
+  })
+})