net/http/httputil: make DumpRequest use Request.RequestURI when available

Fixes #10912

Change-Id: If04e3205d5cc43ebfd6864bc59340c8697cbc0af
Reviewed-on: https://go-review.googlesource.com/17592
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/net/http/httputil/dump.go

@@ -197,15 +197,29 @@ func DumpRequest(req *http.Request, body bool) (dump []byte, err error) {
 
 	var b bytes.Buffer
 
+	// By default, print out the unmodified req.RequestURI, which
+	// is always set for incoming server requests. But because we
+	// previously used req.URL.RequestURI and the docs weren't
+	// always so clear about when to use DumpRequest vs
+	// DumpRequestOut, fall back to the old way if the caller
+	// provides a non-server Request.
+	reqURI := req.RequestURI
+	if reqURI == "" {
+		reqURI = req.URL.RequestURI()
+	}
+
 	fmt.Fprintf(&b, "%s %s HTTP/%d.%d\r\n", valueOrDefault(req.Method, "GET"),
-		req.URL.RequestURI(), req.ProtoMajor, req.ProtoMinor)
+		reqURI, req.ProtoMajor, req.ProtoMinor)
 
-	host := req.Host
-	if host == "" && req.URL != nil {
-		host = req.URL.Host
-	}
-	if host != "" {
-		fmt.Fprintf(&b, "Host: %s\r\n", host)
+	absRequestURI := strings.HasPrefix(req.RequestURI, "http://") || strings.HasPrefix(req.RequestURI, "https://")
+	if !absRequestURI {
+		host := req.Host
+		if host == "" && req.URL != nil {
+			host = req.URL.Host
+		}
+		if host != "" {
+			fmt.Fprintf(&b, "Host: %s\r\n", host)
+		}
 	}
 
 	chunked := len(req.TransferEncoding) > 0 && req.TransferEncoding[0] == "chunked"

src/net/http/httputil/dump_test.go

@@ -5,6 +5,7 @@
 package httputil
 
 import (
+	"bufio"
 	"bytes"
 	"fmt"
 	"io"
@@ -135,6 +136,14 @@ var dumpTests = []dumpTest{
 			"Accept-Encoding: gzip\r\n\r\n" +
 			strings.Repeat("a", 8193),
 	},
+
+	{
+		Req: *mustReadRequest("GET http://foo.com/ HTTP/1.1\r\n" +
+			"User-Agent: blah\r\n\r\n"),
+		NoBody: true,
+		WantDump: "GET http://foo.com/ HTTP/1.1\r\n" +
+			"User-Agent: blah\r\n\r\n",
+	},
 }
 
 func TestDumpRequest(t *testing.T) {
@@ -211,6 +220,14 @@ func mustNewRequest(method, url string, body io.Reader) *http.Request {
 	return req
 }
 
+func mustReadRequest(s string) *http.Request {
+	req, err := http.ReadRequest(bufio.NewReader(strings.NewReader(s)))
+	if err != nil {
+		panic(err)
+	}
+	return req
+}
+
 var dumpResTests = []struct {
 	res  *http.Response
 	body bool