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http2: calculate a correct window increment size for a stream #155

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6 changes: 3 additions & 3 deletions http2/server.go
Original file line number Diff line number Diff line change
Expand Up @@ -2336,13 +2336,13 @@ func (sc *serverConn) sendWindowUpdate(st *stream) {

var n int32
if st == nil {
if avail, windowSize := sc.inflow.available(), sc.srv.initialConnRecvWindowSize(); avail > windowSize/2 {
if avail, windowSize := sc.inflow.n, sc.srv.initialConnRecvWindowSize(); avail > windowSize/2 {
return
} else {
n = windowSize - avail
}
} else {
if avail, windowSize := st.inflow.available(), sc.srv.initialStreamRecvWindowSize(); avail > windowSize/2 {
if avail, windowSize := st.inflow.n, sc.srv.initialStreamRecvWindowSize(); avail > windowSize/2 {
return
} else {
n = windowSize - avail
Expand All @@ -2358,7 +2358,7 @@ func (sc *serverConn) sendWindowUpdate(st *stream) {
sc.sendWindowUpdate32(st, maxUint31)
n -= maxUint31
}
sc.sendWindowUpdate32(st, int32(n))
sc.sendWindowUpdate32(st, n)
}

// st may be nil for conn-level
Expand Down
40 changes: 39 additions & 1 deletion http2/server_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -315,7 +315,7 @@ func (st *serverTester) greetAndCheckSettings(checkSetting func(s Setting) error
if f.FrameHeader.StreamID != 0 {
st.t.Fatalf("WindowUpdate StreamID = %d; want 0", f.FrameHeader.StreamID)
}
incr := uint32((&Server{}).initialConnRecvWindowSize() - initialWindowSize)
incr := uint32(st.sc.srv.initialConnRecvWindowSize() - initialWindowSize)
if f.Increment != incr {
st.t.Fatalf("WindowUpdate increment = %d; want %d", f.Increment, incr)
}
Expand Down Expand Up @@ -1326,6 +1326,44 @@ func TestServer_Handler_Sends_WindowUpdate_Padding(t *testing.T) {
puppet.do(readBodyHandler(t, "def"))
}

// This is a regression test to make sure the correct window increment size is
// calculated for a stream.
// See https://go.dev/issue/56315#issuecomment-1287642591.
func TestServer_Handler_Sends_WindowUpdate_IncrementSize(t *testing.T) {
maxSizePerConn := initialWindowSize * 2
maxSizePerStream := maxSizePerConn*2 + 100

puppet := newHandlerPuppet()
st := newServerTester(t, func(w http.ResponseWriter, r *http.Request) {
puppet.act(w, r)
}, func(s *Server) {
s.MaxUploadBufferPerConnection = int32(maxSizePerConn)
s.MaxUploadBufferPerStream = int32(maxSizePerStream)
})
defer st.Close()
defer puppet.done()

st.greet()

st.writeHeaders(HeadersFrameParam{
StreamID: 1,
BlockFragment: st.encodeHeader(":method", "POST"),
EndStream: false,
EndHeaders: true,
})

st.writeData(1, false, bytes.Repeat([]byte("a"), maxSizePerConn/2))
puppet.do(readBodyHandler(t, strings.Repeat("a", maxSizePerConn/2)))
st.wantWindowUpdate(0, uint32(maxSizePerConn/2))

st.writeData(1, false, bytes.Repeat([]byte("b"), maxSizePerConn/2+100))
puppet.do(readBodyHandler(t, strings.Repeat("b", maxSizePerConn/2+100)))
st.wantWindowUpdate(0, uint32(maxSizePerConn/2+100))
st.wantWindowUpdate(1, uint32(maxSizePerConn+100))

st.writeData(1, true, nil) // END_STREAM here
}

func TestServer_Send_GoAway_After_Bogus_WindowUpdate(t *testing.T) {
st := newServerTester(t, nil)
defer st.Close()
Expand Down