net/http/httputil: fix missing Transfer-Encoding header

Current implementation of httputil.DumpRequestOut
incorrectly resets the Request.Body prematurely
before Content-Length/Transfer-Encoding detection
in newTransferWriter()

This fix avoids resetting the Request.Body when
Request.ContentLength is set to '0' by the caller
and Request.Body is set to a custom reader. To allow
newTransferWriter() to treat this situation as
'Transfer-Encoding: chunked'.

Fixes #34504

Change-Id: Ieab6bf876ced28c32c084e0f4c8c4432964181f5
Reviewed-on: https://go-review.googlesource.com/c/go/+/197898
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/net/http/httputil/dump.go b/src/net/http/httputil/dump.go
index 81c279515617652e8c4ce8104d5cce001b7cd407..c97be066d7d014d5e232a4ee65a55deceee3e68b 100644 (file)
--- a/src/net/http/httputil/dump.go
+++ b/src/net/http/httputil/dump.go
@@ -24,7 +24,7 @@ import (
 // It returns an error if the initial slurp of all bytes fails. It does not attempt
 // to make the returned ReadClosers have identical error-matching behavior.
 func drainBody(b io.ReadCloser) (r1, r2 io.ReadCloser, err error) {
-       if b == http.NoBody {
+       if b == nil || b == http.NoBody {
                // No copying needed. Preserve the magic sentinel meaning of NoBody.
                return http.NoBody, http.NoBody, nil
        }
@@ -60,16 +60,28 @@ func (b neverEnding) Read(p []byte) (n int, err error) {
        return len(p), nil
 }
 
+// outGoingLength is a copy of the unexported
+// (*http.Request).outgoingLength method.
+func outgoingLength(req *http.Request) int64 {
+       if req.Body == nil || req.Body == http.NoBody {
+               return 0
+       }
+       if req.ContentLength != 0 {
+               return req.ContentLength
+       }
+       return -1
+}
+
 // DumpRequestOut is like DumpRequest but for outgoing client requests. It
 // includes any headers that the standard http.Transport adds, such as
 // User-Agent.
 func DumpRequestOut(req *http.Request, body bool) ([]byte, error) {
        save := req.Body
        dummyBody := false
-       if !body || req.Body == nil {
-               req.Body = nil
-               if req.ContentLength != 0 {
-                       req.Body = ioutil.NopCloser(io.LimitReader(neverEnding('x'), req.ContentLength))
+       if !body {
+               contentLength := outgoingLength(req)
+               if contentLength != 0 {
+                       req.Body = ioutil.NopCloser(io.LimitReader(neverEnding('x'), contentLength))
                        dummyBody = true
                }
        } else {

diff --git a/src/net/http/httputil/dump_test.go b/src/net/http/httputil/dump_test.go
index 85731d36f428c354de19557c37c7ef9108508a3a..ead56bc172b258ffc04b5f9d0465a0c20792c6b2 100644 (file)
--- a/src/net/http/httputil/dump_test.go
+++ b/src/net/http/httputil/dump_test.go
@@ -17,6 +17,12 @@ import (
        "testing"
 )
 
+type eofReader struct{}
+
+func (n eofReader) Close() error { return nil }
+
+func (n eofReader) Read([]byte) (int, error) { return 0, io.EOF }
+
 type dumpTest struct {
        // Either Req or GetReq can be set/nil but not both.
        Req    *http.Request
@@ -204,6 +210,29 @@ var dumpTests = []dumpTest{
                        "Content-Length: 0\r\n" +
                        "Accept-Encoding: gzip\r\n\r\n",
        },
+
+       // Issue 34504: a non-nil Body without ContentLength set should be chunked
+       {
+               Req: &http.Request{
+                       Method: "PUT",
+                       URL: &url.URL{
+                               Scheme: "http",
+                               Host:   "post.tld",
+                               Path:   "/test",
+                       },
+                       ContentLength: 0,
+                       Proto:         "HTTP/1.1",
+                       ProtoMajor:    1,
+                       ProtoMinor:    1,
+                       Body:          &eofReader{},
+               },
+               NoBody: true,
+               WantDumpOut: "PUT /test HTTP/1.1\r\n" +
+                       "Host: post.tld\r\n" +
+                       "User-Agent: Go-http-client/1.1\r\n" +
+                       "Transfer-Encoding: chunked\r\n" +
+                       "Accept-Encoding: gzip\r\n\r\n",
+       },
 }
 
 func TestDumpRequest(t *testing.T) {