WIP

index.js

@@ -26,7 +26,10 @@ module.exports.BalancedPool = BalancedPool
 module.exports.Agent = Agent
 module.exports.ProxyAgent = ProxyAgent
 
-// XXX: Re-export redirect and retry handlers...
+module.exports.interceptors = {
+  redirect: require('./lib/interceptors/redirect'),
+  retry: require('./lib/interceptors/retry')
+}
 
 module.exports.buildConnector = buildConnector
 module.exports.errors = errors

lib/api/api-connect.js

@@ -3,7 +3,7 @@
 const { AsyncResource } = require('node:async_hooks')
 const { InvalidArgumentError, RequestAbortedError, SocketError } = require('../core/errors')
 const util = require('../core/util')
-const redirect = require('../handler/RedirectHandler')
+const redirect = require('../interceptors/redirect')
 const { addSignal, removeSignal } = require('./abort-signal')
 
 class ConnectHandler extends AsyncResource {
@@ -91,9 +91,12 @@ function connect (opts, callback) {
   }
 
   try {
-    let dispatch = (opts, handler) => this.dispatch(opts, handler)
-    dispatch = redirect(dispatch)
-    dispatch({ ...opts, method: 'CONNECT' }, new ConnectHandler(opts, callback))
+    this
+      .intercept(dispatcher => opts.maxRedirections ? redirect(dispatcher, null) : dispatcher)
+      .dispatch({
+        ...opts,
+        method: 'CONNECT'
+      }, new ConnectHandler(opts, callback))
   } catch (err) {
     if (typeof callback !== 'function') {
       throw err

lib/api/api-pipeline.js

@@ -13,7 +13,7 @@ const {
   RequestAbortedError
 } = require('../core/errors')
 const util = require('../core/util')
-const redirect = require('../handler/RedirectHandler')
+const redirect = require('../interceptors/redirect')
 const { addSignal, removeSignal } = require('./abort-signal')
 
 const kResume = Symbol('resume')
@@ -241,9 +241,9 @@ function pipeline (opts, handler) {
   try {
     const pipelineHandler = new PipelineHandler(opts, handler)
 
-    let dispatch = (opts, handler) => this.dispatch(opts, handler)
-    dispatch = redirect(dispatch)
-    dispatch({ ...opts, body: pipelineHandler.req }, pipelineHandler)
+    this
+      .intercept(dispatcher => opts.maxRedirections ? redirect(dispatcher, null) : dispatcher)
+      .dispatch({ ...opts, body: pipelineHandler.req }, pipelineHandler)
 
     return pipelineHandler.ret
   } catch (err) {

lib/api/api-request.js

@@ -7,7 +7,7 @@ const {
   RequestAbortedError
 } = require('../core/errors')
 const util = require('../core/util')
-const redirect = require('../handler/RedirectHandler')
+const redirect = require('../interceptors/redirect')
 const { getResolveErrorBodyCallback } = require('./util')
 const { addSignal, removeSignal } = require('./abort-signal')
 
@@ -167,9 +167,9 @@ function request (opts, callback) {
   }
 
   try {
-    let dispatch = (opts, handler) => this.dispatch(opts, handler)
-    dispatch = redirect(dispatch)
-    dispatch(opts, new RequestHandler(opts, callback))
+    this
+      .intercept(dispatcher => opts.maxRedirections ? redirect(dispatcher, null) : dispatcher)
+      .dispatch(opts, new RequestHandler(opts, callback))
   } catch (err) {
     if (typeof callback !== 'function') {
       throw err

lib/api/api-stream.js

@@ -7,7 +7,7 @@ const {
   RequestAbortedError
 } = require('../core/errors')
 const util = require('../core/util')
-const redirect = require('../handler/RedirectHandler')
+const redirect = require('../interceptors/redirect')
 const { getResolveErrorBodyCallback } = require('./util')
 const { AsyncResource } = require('node:async_hooks')
 const { addSignal, removeSignal } = require('./abort-signal')
@@ -208,9 +208,9 @@ function stream (opts, factory, callback) {
   }
 
   try {
-    let dispatch = (opts, handler) => this.dispatch(opts, handler)
-    dispatch = redirect(dispatch)
-    dispatch(opts, new StreamHandler(opts, factory, callback))
+    this
+      .intercept(dispatcher => opts.maxRedirections ? redirect(dispatcher, null) : dispatcher)
+      .dispatch(opts, new StreamHandler(opts, factory, callback))
   } catch (err) {
     if (typeof callback !== 'function') {
       throw err

lib/api/api-upgrade.js

@@ -4,7 +4,7 @@ const assert = require('node:assert')
 const { AsyncResource } = require('node:async_hooks')
 const { InvalidArgumentError, RequestAbortedError, SocketError } = require('../core/errors')
 const util = require('../core/util')
-const redirect = require('../handler/RedirectHandler')
+const redirect = require('../interceptors/redirect')
 const { addSignal, removeSignal } = require('./abort-signal')
 
 class UpgradeHandler extends AsyncResource {
@@ -88,13 +88,13 @@ function upgrade (opts, callback) {
   }
 
   try {
-    let dispatch = (opts, handler) => this.dispatch(opts, handler)
-    dispatch = redirect(dispatch)
-    dispatch({
-      ...opts,
-      method: opts.method || 'GET',
-      upgrade: opts.protocol || 'Websocket'
-    }, new UpgradeHandler(opts, callback))
+    this
+      .intercept(dispatcher => opts.maxRedirections ? redirect(dispatcher, null) : dispatcher)
+      .dispatch({
+        ...opts,
+        method: opts.method || 'GET',
+        upgrade: opts.protocol || 'Websocket'
+      }, new UpgradeHandler(opts, callback))
   } catch (err) {
     if (typeof callback !== 'function') {
       throw err

lib/dispatcher.js

@@ -2,7 +2,11 @@
 
 const EventEmitter = require('node:events')
 
+const kDispatcherVersion = Symbol.for('undici.dispatcher.version')
+
 class Dispatcher extends EventEmitter {
+  [kDispatcherVersion] = 1
+
   dispatch () {
     throw new Error('not implemented')
   }
@@ -14,6 +18,20 @@ class Dispatcher extends EventEmitter {
   destroy () {
     throw new Error('not implemented')
   }
+
+  intercept (...interceptors) {
+    let dispatcher = this
+    for (const interceptor of interceptors) {
+      if (typeof interceptor !== 'function') {
+        throw new Error('invalid interceptor')
+      }
+      dispatcher = interceptor(dispatcher) ?? dispatcher
+      if (dispatcher[kDispatcherVersion] !== 1) {
+        throw new Error('invalid dispatcher')
+      }
+    }
+    return dispatcher
+  }
 }
 
 module.exports = Dispatcher

lib/handler/RedirectHandler.js → lib/interceptors/redirect.js

@@ -24,28 +24,14 @@ class BodyAsyncIterable {
 }
 
 class RedirectHandler {
-  static decorate (dispatch) {
-    return (opts, handler) => {
-      if (opts?.maxRedirections == null || opts.maxRedirections === 0) {
-        return dispatch(opts, handler)
-      }
-
-      if (!Number.isInteger(opts.maxRedirections) || opts.maxRedirections < 0) {
-        throw new InvalidArgumentError('maxRedirections must be a positive number')
-      }
-
-      return dispatch(opts, new RedirectHandler(dispatch, opts.maxRedirections, opts, handler))
-    }
-  }
-
-  constructor (dispatch, maxRedirections, opts, handler) {
+  constructor (dispatcher, maxRedirections, opts, handler) {
     if (maxRedirections != null && (!Number.isInteger(maxRedirections) || maxRedirections < 0)) {
       throw new InvalidArgumentError('maxRedirections must be a positive number')
     }
 
     util.validateHandler(handler, opts.method, opts.upgrade)
 
-    this.dispatch = dispatch
+    this.dispatcher = dispatcher
     this.location = null
     this.abort = null
     this.opts = { ...opts, maxRedirections: 0 } // opts must be a copy
@@ -182,7 +168,7 @@ class RedirectHandler {
       this.location = null
       this.abort = null
 
-      this.dispatch(this.opts, this)
+      this.dispatcher.dispatch(this.opts, this)
     } else {
       this.handler.onComplete(trailers)
     }
@@ -237,4 +223,38 @@ function cleanRequestHeaders (headers, removeContent, unknownOrigin) {
   return ret
 }
 
-module.exports = RedirectHandler.decorate
+class RedirectDispatcher {
+  #maxRedirections
+  #dispatcher
+
+  constructor (dispatcher, opts) {
+    if (opts?.maxRedirections != null && (!Number.isInteger(opts.maxRedirections) || opts.maxRedirections < 0)) {
+      throw new InvalidArgumentError('maxRedirections must be a positive number')
+    }
+
+    this.#maxRedirections = opts?.maxRedirections
+    this.#dispatcher = dispatcher
+  }
+
+  dispatch (opts, handler) {
+    const maxRedirections = opts.maxRedirections ?? this.#maxRedirections
+
+    if (maxRedirections != null && (!Number.isInteger(maxRedirections) || maxRedirections < 0)) {
+      throw new InvalidArgumentError('maxRedirections must be a positive number')
+    }
+
+    return maxRedirections
+      ? this.#dispatcher.dispatch(opts, new RedirectHandler(this.#dispatcher, opts.maxRedirections, opts, handler))
+      : this.#dispatcher.dispatch(opts, handler)
+  }
+
+  close (...args) {
+    return this.#dispatcher.close(...args)
+  }
+
+  destroy (...args) {
+    return this.#dispatcher.destroy(...args)
+  }
+}
+
+module.exports = (dispatcher, opts) => new RedirectDispatcher(dispatcher, opts)

lib/handler/RetryHandler.js → lib/interceptors/retry.js

@@ -332,4 +332,24 @@ class RetryHandler {
   }
 }
 
-module.exports = RetryHandler
+class RetryDispatcher {
+  #dispatcher
+
+  constructor (dispatcher, opts) {
+    this.#dispatcher = dispatcher
+  }
+
+  dispatch (opts, handler) {
+    return this.#dispatcher.dispatch(opts, new RetryHandler(opts, handler))
+  }
+
+  close (...args) {
+    return this.#dispatcher.close(...args)
+  }
+
+  destroy (...args) {
+    return this.#dispatcher.destroy(...args)
+  }
+}
+
+module.exports = (dispatcher, opts) => new RetryDispatcher(dispatcher, opts)