feat: add transferTrailer to switch whether forward trailer-relative header

go.mod

@@ -2,4 +2,4 @@ module github.com/hertz-contrib/reverseproxy
 
 go 1.16
 
-require github.com/cloudwego/hertz v0.3.0
+require github.com/cloudwego/hertz v0.6.5

go.sum

@@ -2,72 +2,86 @@ github.com/bytedance/go-tagexpr/v2 v2.9.2 h1:QySJaAIQgOEDQBLS3x9BxOWrnhqu5sQ+f6H
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reverse_proxy.go

@@ -1,5 +1,5 @@
 /*
- *	Copyright 2022 CloudWeGo Authors
+ *	Copyright 2023 CloudWeGo Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,7 +18,7 @@
  * license that can be found in the LICENSE file.
  *
  * This file may have been modified by CloudWeGo Authors. All CloudWeGo
- * Modifications are Copyright 2022 CloudWeGo Authors.
+ * Modifications are Copyright 2023 CloudWeGo Authors.
  */
 
 package reverseproxy
@@ -47,6 +47,9 @@ type ReverseProxy struct {
 	// target is set as a reverse proxy address
 	Target string
 
+	// transforTrailer is whether to forward Trailer-related header
+	transferTrailer bool
+
 	// director must be a function which modifies the request
 	// into a new request. Its response is then redirected
 	// back to the original client unmodified.
@@ -191,6 +194,18 @@ func removeResponseConnHeaders(c *app.RequestContext) {
 	})
 }
 
+// checkTeHeader check RequestHeader if has 'Te: trailers'
+// See https://github.com/golang/go/issues/21096
+func checkTeHeader(header *protocol.RequestHeader) bool {
+	teHeaders := header.PeekAll("Te")
+	for _, te := range teHeaders {
+		if bytes.Contains(te, []byte("trailers")) {
+			return true
+		}
+	}
+	return false
+}
+
 func (r *ReverseProxy) defaultErrorHandler(c *app.RequestContext, _ error) {
 	c.Response.Header.SetStatusCode(consts.StatusBadGateway)
 }
@@ -204,14 +219,27 @@ func (r *ReverseProxy) ServeHTTP(c context.Context, ctx *app.RequestContext) {
 	}
 	req.Header.ResetConnectionClose()
 
+	hasTeTrailer := false
+	if r.transferTrailer {
+		hasTeTrailer = checkTeHeader(&req.Header)
+	}
+
 	removeRequestConnHeaders(ctx)
 	// Remove hop-by-hop headers to the backend. Especially
 	// important is "Connection" because we want a persistent
 	// connection, regardless of what the client sent to us.
 	for _, h := range hopHeaders {
+		if r.transferTrailer && h == "Trailer" {
+			continue
+		}
 		req.Header.DelBytes(s2b(h))
 	}
 
+	// Check if 'trailers' exists in te header, If exists, add an additional Te header
+	if r.transferTrailer && hasTeTrailer {
+		req.Header.Set("Te", "trailers")
+	}
+
 	// prepare request(replace headers and some URL host)
 	if ip, _, err := net.SplitHostPort(ctx.RemoteAddr().String()); err == nil {
 		tmp := req.Header.Peek("X-Forwarded-For")
@@ -236,6 +264,9 @@ func (r *ReverseProxy) ServeHTTP(c context.Context, ctx *app.RequestContext) {
 	removeResponseConnHeaders(ctx)
 
 	for _, h := range hopHeaders {
+		if r.transferTrailer && h == "Trailer" {
+			continue
+		}
 		resp.Header.DelBytes(s2b(h))
 	}
 
@@ -268,6 +299,10 @@ func (r *ReverseProxy) SetErrorHandler(eh func(c *app.RequestContext, err error)
 	r.errorHandler = eh
 }
 
+func (r *ReverseProxy) SetTransferTrailer(b bool) {
+	r.transferTrailer = b
+}
+
 func (r *ReverseProxy) getErrorHandler() func(c *app.RequestContext, err error) {
 	if r.errorHandler != nil {
 		return r.errorHandler

reverse_proxy_test.go

@@ -1,5 +1,5 @@
 /*
- *	Copyright 2022 CloudWeGo Authors
+ *	Copyright 2023 CloudWeGo Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,7 +18,7 @@
  * license that can be found in the LICENSE file.
  *
  * This file may have been modified by CloudWeGo Authors. All CloudWeGo
- * Modifications are Copyright 2022 CloudWeGo Authors.
+ * Modifications are Copyright 2023 CloudWeGo Authors.
  */
 
 package reverseproxy
@@ -40,8 +40,10 @@ import (
 )
 
 // Reverse proxy tests.
-const fakeHopHeader = "X-Fake-Hop-Header-For-Test"
-const fakeConnectionToken = "X-Fake-Connection-Token"
+const (
+	fakeHopHeader       = "X-Fake-Hop-Header-For-Test"
+	fakeConnectionToken = "X-Fake-Connection-Token"
+)
 
 func init() {
 	hopHeaders = append(hopHeaders, fakeHopHeader)
@@ -486,3 +488,71 @@ func TestReverseProxyErrorHandler(t *testing.T) {
 		t.Errorf("got res.StatusCode %d; expected %d", g, e)
 	}
 }
+
+func TestReverseProxyTransferTrailer(t *testing.T) {
+	const backendResponse = "I am the backend"
+	r := server.New(server.WithHostPorts("127.0.0.1:9999"), server.WithStreamBody(true))
+
+	r.GET("/proxy/backend", func(cc context.Context, ctx *app.RequestContext) {
+		if c := ctx.Request.Header.Get("Te"); c != "trailers" {
+			t.Errorf("handler got Te header value %q; want 'trailers'", c)
+		}
+
+		if c := ctx.Request.Header.Get("Trailer"); c != "X-Trailer" {
+			t.Errorf("handler got Trailer header value %q; want 'X-Trailer'", c)
+		}
+
+		if g, e := string(ctx.Request.Body()), backendResponse; g != e {
+			t.Errorf("got body %q; expected %q", g, e)
+		}
+
+		if c := ctx.Request.Header.Trailer().Get("X-Trailer"); c != "trailer_value" {
+			t.Errorf("handler got X-Trailer Trailer value %q; want 'trailer_value'", c)
+		}
+
+		ctx.Response.Header.Set("Trailer", "X-Trailer")
+		ctx.Response.Header.Trailer().Set("X-Trailer", "trailer_value")
+		ctx.Response.SetBodyStream(strings.NewReader(backendResponse), -1)
+	})
+
+	proxy, err := NewSingleHostReverseProxy("http://127.0.0.1:9999/proxy", client.WithResponseBodyStream(true))
+	if err != nil {
+		t.Errorf("proxy error: %v", err)
+	}
+	proxy.SetTransferTrailer(true)
+
+	r.GET("/backend", func(c context.Context, ctx *app.RequestContext) {
+		proxy.ServeHTTP(c, ctx)
+	})
+	go r.Spin()
+	time.Sleep(time.Second)
+	cli, _ := client.NewClient(client.WithResponseBodyStream(true))
+	req := protocol.AcquireRequest()
+	res := protocol.AcquireResponse()
+	req.Header.Set("Connection", "close, TE")
+	req.Header.Add("Te", "foo")
+	req.Header.Add("Te", "bar, trailers")
+	req.Header.Set("Proxy-Connection", "should be deleted")
+	req.Header.Set("Upgrade", "foo")
+	req.Header.Trailer().Set("X-Trailer", "trailer_value")
+	req.SetConnectionClose()
+	req.SetHost("some-name")
+	req.SetRequestURI("http://localhost:9999/backend")
+	req.SetBodyStream(strings.NewReader(backendResponse), -1)
+	cli.Do(context.Background(), req, res)
+	if err != nil {
+		t.Fatalf("Get: %v", err)
+	}
+
+	if h := res.Header.Get("Trailer"); h != "X-Trailer" {
+		t.Errorf("header Trailer = %q; want %q", h, "X-Trailer")
+	}
+
+	if g, e := string(res.Body()), backendResponse; g != e {
+		t.Errorf("got body %q; expected %q", g, e)
+	}
+
+	if c := res.Header.Trailer().Get("X-Trailer"); c != "trailer_value" {
+		t.Errorf("handler got X-Trailer Trailer value %q; want 'trailer_value'", c)
+	}
+}