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net/http: send body or close connection on expect-100-continue requests 

When sending a request with an "Expect: 100-continue" header,
we must send the request body before sending any further requests
on the connection.

When receiving a non-1xx response to an "Expect: 100-continue" request,
send the request body if the connection isn't being closed after
processing the response. In other words, if either the request
or response contains a "Connection: close" header, then skip sending
the request body (because the connection will not be used for
further requests), but otherwise send it.

Correct a comment on the server-side Expect: 100-continue handling
that implied sending the request body is optional. It isn't.

For #67555

Change-Id: Ia2f12091bee697771087f32ac347509ec5922d54
Reviewed-on: https://go-review.googlesource.com/c/go/+/591255
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
This commit is contained in:
Damien Neil 2024-06-06 12:50:46 -07:00
parent 2f6ba0c294
commit cf501e05e1
3 changed files with 164 additions and 97 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
src/net/http/server.go
View File

@ -1399,16 +1399,21 @@ func (cw *chunkWriter) writeHeader(p []byte) {
// If the client wanted a 100-continue but we never sent it to
// them (or, more strictly: we never finished reading their
// request body), don't reuse this connection because it's now
// in an unknown state: we might be sending this response at
// the same time the client is now sending its request body
// after a timeout. (Some HTTP clients send Expect:
// 100-continue but knowing that some servers don't support
// it, the clients set a timer and send the body later anyway)
// If we haven't seen EOF, we can't skip over the unread body
// because we don't know if the next bytes on the wire will be
// the body-following-the-timer or the subsequent request.
// See Issue 11549.
// request body), don't reuse this connection.
//
// This behavior was first added on the theory that we don't know
// if the next bytes on the wire are going to be the remainder of
// the request body or the subsequent request (see issue 11549),
// but that's not correct: If we keep using the connection,
// the client is required to send the request body whether we
// asked for it or not.
//
// We probably do want to skip reusing the connection in most cases,
// however. If the client is offering a large request body that we
// don't intend to use, then it's better to close the connection
// than to read the body. For now, assume that if we're sending
// headers, the handler is done reading the body and we should
// drop the connection if we haven't seen EOF.
if ecr, ok := w.req.Body.(*expectContinueReader); ok && !ecr.sawEOF.Load() {
w.closeAfterReply = true
}

34
src/net/http/transport.go
View File

@ -2397,17 +2397,12 @@ func (pc *persistConn) readResponse(rc requestAndChan, trace *httptrace.ClientTr
return
}
resCode := resp.StatusCode
if continueCh != nil {
if resCode == 100 {
if trace != nil && trace.Got100Continue != nil {
trace.Got100Continue()
}
continueCh <- struct{}{}
continueCh = nil
} else if resCode >= 200 {
close(continueCh)
continueCh = nil
if continueCh != nil && resCode == StatusContinue {
if trace != nil && trace.Got100Continue != nil {
trace.Got100Continue()
}
continueCh <- struct{}{}
continueCh = nil
}
is1xx := 100 <= resCode && resCode <= 199
// treat 101 as a terminal status, see issue 26161
@ -2430,6 +2425,25 @@ func (pc *persistConn) readResponse(rc requestAndChan, trace *httptrace.ClientTr
if resp.isProtocolSwitch() {
resp.Body = newReadWriteCloserBody(pc.br, pc.conn)
}
if continueCh != nil {
// We send an "Expect: 100-continue" header, but the server
// responded with a terminal status and no 100 Continue.
//
// If we're going to keep using the connection, we need to send the request body.
// Tell writeLoop to skip sending the body if we're going to close the connection,
// or to send it otherwise.
//
// The case where we receive a 101 Switching Protocols response is a bit
// ambiguous, since we don't know what protocol we're switching to.
// Conceivably, it's one that doesn't need us to send the body.
// Given that we'll send the body if ExpectContinueTimeout expires,
// be consistent and always send it if we aren't closing the connection.
if resp.Close || rc.treq.Request.Close {
close(continueCh) // don't send the body; the connection will close
} else {
continueCh <- struct{}{} // send the body
}
}
resp.TLS = pc.tlsState
return

202
src/net/http/transport_test.go
View File

@ -1185,94 +1185,142 @@ func testTransportGzip(t *testing.T, mode testMode) {
}
}
// If a request has Expect:100-continue header, the request blocks sending body until the first response.
// Premature consumption of the request body should not be occurred.
func TestTransportExpect100Continue(t *testing.T) {
run(t, testTransportExpect100Continue, []testMode{http1Mode})
// A transport100Continue test exercises Transport behaviors when sending a
// request with an Expect: 100-continue header.
type transport100ContinueTest struct {
t *testing.T
reqdone chan struct{}
resp *Response
respErr error
conn net.Conn
reader *bufio.Reader
}
func testTransportExpect100Continue(t *testing.T, mode testMode) {
ts := newClientServerTest(t, mode, HandlerFunc(func(rw ResponseWriter, req *Request) {
switch req.URL.Path {
case "/100":
// This endpoint implicitly responds 100 Continue and reads body.
if _, err := io.Copy(io.Discard, req.Body); err != nil {
t.Error("Failed to read Body", err)
}
rw.WriteHeader(StatusOK)
case "/200":
// Go 1.5 adds Connection: close header if the client expect
// continue but not entire request body is consumed.
rw.WriteHeader(StatusOK)
case "/500":
rw.WriteHeader(StatusInternalServerError)
case "/keepalive":
// This hijacked endpoint responds error without Connection:close.
_, bufrw, err := rw.(Hijacker).Hijack()
if err != nil {
log.Fatal(err)
}
bufrw.WriteString("HTTP/1.1 500 Internal Server Error\r\n")
bufrw.WriteString("Content-Length: 0\r\n\r\n")
bufrw.Flush()
case "/timeout":
// This endpoint tries to read body without 100 (Continue) response.
// After ExpectContinueTimeout, the reading will be started.
conn, bufrw, err := rw.(Hijacker).Hijack()
if err != nil {
log.Fatal(err)
}
if _, err := io.CopyN(io.Discard, bufrw, req.ContentLength); err != nil {
t.Error("Failed to read Body", err)
}
bufrw.WriteString("HTTP/1.1 200 OK\r\n\r\n")
bufrw.Flush()
conn.Close()
}
})).ts
const transport100ContinueTestBody = "request body"
tests := []struct {
path string
body []byte
sent int
status int
}{
{path: "/100", body: []byte("hello"), sent: 5, status: 200}, // Got 100 followed by 200, entire body is sent.
{path: "/200", body: []byte("hello"), sent: 0, status: 200}, // Got 200 without 100. body isn't sent.
{path: "/500", body: []byte("hello"), sent: 0, status: 500}, // Got 500 without 100. body isn't sent.
{path: "/keepalive", body: []byte("hello"), sent: 0, status: 500}, // Although without Connection:close, body isn't sent.
{path: "/timeout", body: []byte("hello"), sent: 5, status: 200}, // Timeout exceeded and entire body is sent.
// newTransport100ContinueTest creates a Transport and sends an Expect: 100-continue
// request on it.
func newTransport100ContinueTest(t *testing.T, timeout time.Duration) *transport100ContinueTest {
ln := newLocalListener(t)
defer ln.Close()
test := &transport100ContinueTest{
t: t,
reqdone: make(chan struct{}),
}
c := ts.Client()
for i, v := range tests {
tr := &Transport{
ExpectContinueTimeout: 2 * time.Second,
}
defer tr.CloseIdleConnections()
c.Transport = tr
body := bytes.NewReader(v.body)
req, err := NewRequest("PUT", ts.URL+v.path, body)
if err != nil {
t.Fatal(err)
}
tr := &Transport{
ExpectContinueTimeout: timeout,
}
go func() {
defer close(test.reqdone)
body := strings.NewReader(transport100ContinueTestBody)
req, _ := NewRequest("PUT", "http://"+ln.Addr().String(), body)
req.Header.Set("Expect", "100-continue")
req.ContentLength = int64(len(v.body))
req.ContentLength = int64(len(transport100ContinueTestBody))
test.resp, test.respErr = tr.RoundTrip(req)
test.resp.Body.Close()
}()
resp, err := c.Do(req)
if err != nil {
t.Fatal(err)
c, err := ln.Accept()
if err != nil {
t.Fatalf("Accept: %v", err)
}
t.Cleanup(func() {
c.Close()
})
br := bufio.NewReader(c)
_, err = ReadRequest(br)
if err != nil {
t.Fatalf("ReadRequest: %v", err)
}
test.conn = c
test.reader = br
t.Cleanup(func() {
<-test.reqdone
tr.CloseIdleConnections()
got, _ := io.ReadAll(test.reader)
if len(got) > 0 {
t.Fatalf("Transport sent unexpected bytes: %q", got)
}
resp.Body.Close()
})
sent := len(v.body) - body.Len()
if v.status != resp.StatusCode {
t.Errorf("test %d: status code should be %d but got %d. (%s)", i, v.status, resp.StatusCode, v.path)
}
if v.sent != sent {
t.Errorf("test %d: sent body should be %d but sent %d. (%s)", i, v.sent, sent, v.path)
return test
}
// respond sends response lines from the server to the transport.
func (test *transport100ContinueTest) respond(lines ...string) {
for _, line := range lines {
if _, err := test.conn.Write([]byte(line + "\r\n")); err != nil {
test.t.Fatalf("Write: %v", err)
}
}
if _, err := test.conn.Write([]byte("\r\n")); err != nil {
test.t.Fatalf("Write: %v", err)
}
}
// wantBodySent ensures the transport has sent the request body to the server.
func (test *transport100ContinueTest) wantBodySent() {
got, err := io.ReadAll(io.LimitReader(test.reader, int64(len(transport100ContinueTestBody))))
if err != nil {
test.t.Fatalf("unexpected error reading body: %v", err)
}
if got, want := string(got), transport100ContinueTestBody; got != want {
test.t.Fatalf("unexpected body: got %q, want %q", got, want)
}
}
// wantRequestDone ensures the Transport.RoundTrip has completed with the expected status.
func (test *transport100ContinueTest) wantRequestDone(want int) {
<-test.reqdone
if test.respErr != nil {
test.t.Fatalf("unexpected RoundTrip error: %v", test.respErr)
}
if got := test.resp.StatusCode; got != want {
test.t.Fatalf("unexpected response code: got %v, want %v", got, want)
}
}
func TestTransportExpect100ContinueSent(t *testing.T) {
test := newTransport100ContinueTest(t, 1*time.Hour)
// Server sends a 100 Continue response, and the client sends the request body.
test.respond("HTTP/1.1 100 Continue")
test.wantBodySent()
test.respond("HTTP/1.1 200", "Content-Length: 0")
test.wantRequestDone(200)
}
func TestTransportExpect100Continue200ResponseNoConnClose(t *testing.T) {
test := newTransport100ContinueTest(t, 1*time.Hour)
// No 100 Continue response, no Connection: close header.
test.respond("HTTP/1.1 200", "Content-Length: 0")
test.wantBodySent()
test.wantRequestDone(200)
}
func TestTransportExpect100Continue200ResponseWithConnClose(t *testing.T) {
test := newTransport100ContinueTest(t, 1*time.Hour)
// No 100 Continue response, Connection: close header set.
test.respond("HTTP/1.1 200", "Connection: close", "Content-Length: 0")
test.wantRequestDone(200)
}
func TestTransportExpect100Continue500ResponseNoConnClose(t *testing.T) {
test := newTransport100ContinueTest(t, 1*time.Hour)
// No 100 Continue response, no Connection: close header.
test.respond("HTTP/1.1 500", "Content-Length: 0")
test.wantBodySent()
test.wantRequestDone(500)
}
func TestTransportExpect100Continue500ResponseTimeout(t *testing.T) {
test := newTransport100ContinueTest(t, 5*time.Millisecond) // short timeout
test.wantBodySent() // after timeout
test.respond("HTTP/1.1 200", "Content-Length: 0")
test.wantRequestDone(200)
}
func TestSOCKS5Proxy(t *testing.T) {