[chore]: Bump golang.org/x/net from 0.4.0 to 0.5.0 (#1319)

Bumps [golang.org/x/net](https://github.com/golang/net) from 0.4.0 to 0.5.0.
- [Release notes](https://github.com/golang/net/releases)
- [Commits](https://github.com/golang/net/compare/v0.4.0...v0.5.0)

---
updated-dependencies:
- dependency-name: golang.org/x/net
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

3 files changed, 144 insertions, 115 deletions

diff --git a/vendor/golang.org/x/net/http2/flow.go b/vendor/golang.org/x/net/http2/flow.go
index b51f0e0cf..750ac52f2 100644
--- a/vendor/golang.org/x/net/http2/flow.go
+++ b/vendor/golang.org/x/net/http2/flow.go
@@ -6,23 +6,91 @@
 
 package http2
 
-// flow is the flow control window's size.
-type flow struct {
+// inflowMinRefresh is the minimum number of bytes we'll send for a
+// flow control window update.
+const inflowMinRefresh = 4 << 10
+
+// inflow accounts for an inbound flow control window.
+// It tracks both the latest window sent to the peer (used for enforcement)
+// and the accumulated unsent window.
+type inflow struct {
+	avail  int32
+	unsent int32
+}
+
+// set sets the initial window.
+func (f *inflow) init(n int32) {
+	f.avail = n
+}
+
+// add adds n bytes to the window, with a maximum window size of max,
+// indicating that the peer can now send us more data.
+// For example, the user read from a {Request,Response} body and consumed
+// some of the buffered data, so the peer can now send more.
+// It returns the number of bytes to send in a WINDOW_UPDATE frame to the peer.
+// Window updates are accumulated and sent when the unsent capacity
+// is at least inflowMinRefresh or will at least double the peer's available window.
+func (f *inflow) add(n int) (connAdd int32) {
+	if n < 0 {
+		panic("negative update")
+	}
+	unsent := int64(f.unsent) + int64(n)
+	// "A sender MUST NOT allow a flow-control window to exceed 2^31-1 octets."
+	// RFC 7540 Section 6.9.1.
+	const maxWindow = 1<<31 - 1
+	if unsent+int64(f.avail) > maxWindow {
+		panic("flow control update exceeds maximum window size")
+	}
+	f.unsent = int32(unsent)
+	if f.unsent < inflowMinRefresh && f.unsent < f.avail {
+		// If there aren't at least inflowMinRefresh bytes of window to send,
+		// and this update won't at least double the window, buffer the update for later.
+		return 0
+	}
+	f.avail += f.unsent
+	f.unsent = 0
+	return int32(unsent)
+}
+
+// take attempts to take n bytes from the peer's flow control window.
+// It reports whether the window has available capacity.
+func (f *inflow) take(n uint32) bool {
+	if n > uint32(f.avail) {
+		return false
+	}
+	f.avail -= int32(n)
+	return true
+}
+
+// takeInflows attempts to take n bytes from two inflows,
+// typically connection-level and stream-level flows.
+// It reports whether both windows have available capacity.
+func takeInflows(f1, f2 *inflow, n uint32) bool {
+	if n > uint32(f1.avail) || n > uint32(f2.avail) {
+		return false
+	}
+	f1.avail -= int32(n)
+	f2.avail -= int32(n)
+	return true
+}
+
+// outflow is the outbound flow control window's size.
+type outflow struct {
 	_ incomparable
 
 	// n is the number of DATA bytes we're allowed to send.
-	// A flow is kept both on a conn and a per-stream.
+	// An outflow is kept both on a conn and a per-stream.
 	n int32
 
-	// conn points to the shared connection-level flow that is
-	// shared by all streams on that conn. It is nil for the flow
+	// conn points to the shared connection-level outflow that is
+	// shared by all streams on that conn. It is nil for the outflow
 	// that's on the conn directly.
-	conn *flow
+	conn *outflow
 }
 
-func (f *flow) setConnFlow(cf *flow) { f.conn = cf }
+func (f *outflow) setConnFlow(cf *outflow) { f.conn = cf }
 
-func (f *flow) available() int32 {
+func (f *outflow) available() int32 {
 	n := f.n
 	if f.conn != nil && f.conn.n < n {
 		n = f.conn.n
@@ -30,7 +98,7 @@ func (f *flow) available() int32 {
 	return n
 }
 
-func (f *flow) take(n int32) {
+func (f *outflow) take(n int32) {
 	if n > f.available() {
 		panic("internal error: took too much")
 	}
@@ -42,7 +110,7 @@ func (f *flow) take(n int32) {
 
 // add adds n bytes (positive or negative) to the flow control window.
 // It returns false if the sum would exceed 2^31-1.
-func (f *flow) add(n int32) bool {
+func (f *outflow) add(n int32) bool {
 	sum := f.n + n
 	if (sum > n) == (f.n > 0) {
 		f.n = sum
diff --git a/vendor/golang.org/x/net/http2/server.go b/vendor/golang.org/x/net/http2/server.go
index 4eb7617fa..b624dc0a7 100644
--- a/vendor/golang.org/x/net/http2/server.go
+++ b/vendor/golang.org/x/net/http2/server.go
@@ -448,7 +448,7 @@ func (s *Server) ServeConn(c net.Conn, opts *ServeConnOpts) {
 	// configured value for inflow, that will be updated when we send a
 	// WINDOW_UPDATE shortly after sending SETTINGS.
 	sc.flow.add(initialWindowSize)
-	sc.inflow.add(initialWindowSize)
+	sc.inflow.init(initialWindowSize)
 	sc.hpackEncoder = hpack.NewEncoder(&sc.headerWriteBuf)
 	sc.hpackEncoder.SetMaxDynamicTableSizeLimit(s.maxEncoderHeaderTableSize())
 
@@ -563,8 +563,8 @@ type serverConn struct {
 	wroteFrameCh     chan frameWriteResult  // from writeFrameAsync -> serve, tickles more frame writes
 	bodyReadCh       chan bodyReadMsg       // from handlers -> serve
 	serveMsgCh       chan interface{}       // misc messages & code to send to / run on the serve loop
-	flow             flow                   // conn-wide (not stream-specific) outbound flow control
-	inflow           flow                   // conn-wide inbound flow control
+	flow             outflow                // conn-wide (not stream-specific) outbound flow control
+	inflow           inflow                 // conn-wide inbound flow control
 	tlsState         *tls.ConnectionState   // shared by all handlers, like net/http
 	remoteAddrStr    string
 	writeSched       WriteScheduler
@@ -641,10 +641,10 @@ type stream struct {
 	cancelCtx func()
 
 	// owned by serverConn's serve loop:
-	bodyBytes        int64 // body bytes seen so far
-	declBodyBytes    int64 // or -1 if undeclared
-	flow             flow  // limits writing from Handler to client
-	inflow           flow  // what the client is allowed to POST/etc to us
+	bodyBytes        int64   // body bytes seen so far
+	declBodyBytes    int64   // or -1 if undeclared
+	flow             outflow // limits writing from Handler to client
+	inflow           inflow  // what the client is allowed to POST/etc to us
 	state            streamState
 	resetQueued      bool        // RST_STREAM queued for write; set by sc.resetStream
 	gotTrailerHeader bool        // HEADER frame for trailers was seen
@@ -1503,7 +1503,7 @@ func (sc *serverConn) processFrame(f Frame) error {
 	if sc.inGoAway && (sc.goAwayCode != ErrCodeNo || f.Header().StreamID > sc.maxClientStreamID) {
 
 		if f, ok := f.(*DataFrame); ok {
-			if sc.inflow.available() < int32(f.Length) {
+			if !sc.inflow.take(f.Length) {
 				return sc.countError("data_flow", streamError(f.Header().StreamID, ErrCodeFlowControl))
 			}
 			sc.sendWindowUpdate(nil, int(f.Length)) // conn-level
@@ -1775,14 +1775,9 @@ func (sc *serverConn) processData(f *DataFrame) error {
 		// But still enforce their connection-level flow control,
 		// and return any flow control bytes since we're not going
 		// to consume them.
-		if sc.inflow.available() < int32(f.Length) {
+		if !sc.inflow.take(f.Length) {
 			return sc.countError("data_flow", streamError(id, ErrCodeFlowControl))
 		}
-		// Deduct the flow control from inflow, since we're
-		// going to immediately add it back in
-		// sendWindowUpdate, which also schedules sending the
-		// frames.
-		sc.inflow.take(int32(f.Length))
 		sc.sendWindowUpdate(nil, int(f.Length)) // conn-level
 
 		if st != nil && st.resetQueued {
@@ -1797,10 +1792,9 @@ func (sc *serverConn) processData(f *DataFrame) error {
 
 	// Sender sending more than they'd declared?
 	if st.declBodyBytes != -1 && st.bodyBytes+int64(len(data)) > st.declBodyBytes {
-		if sc.inflow.available() < int32(f.Length) {
+		if !sc.inflow.take(f.Length) {
 			return sc.countError("data_flow", streamError(id, ErrCodeFlowControl))
 		}
-		sc.inflow.take(int32(f.Length))
 		sc.sendWindowUpdate(nil, int(f.Length)) // conn-level
 
 		st.body.CloseWithError(fmt.Errorf("sender tried to send more than declared Content-Length of %d bytes", st.declBodyBytes))
@@ -1811,10 +1805,9 @@ func (sc *serverConn) processData(f *DataFrame) error {
 	}
 	if f.Length > 0 {
 		// Check whether the client has flow control quota.
-		if st.inflow.available() < int32(f.Length) {
+		if !takeInflows(&sc.inflow, &st.inflow, f.Length) {
 			return sc.countError("flow_on_data_length", streamError(id, ErrCodeFlowControl))
 		}
-		st.inflow.take(int32(f.Length))
 
 		if len(data) > 0 {
 			wrote, err := st.body.Write(data)
@@ -1830,10 +1823,12 @@ func (sc *serverConn) processData(f *DataFrame) error {
 
 		// Return any padded flow control now, since we won't
 		// refund it later on body reads.
-		if pad := int32(f.Length) - int32(len(data)); pad > 0 {
-			sc.sendWindowUpdate32(nil, pad)
-			sc.sendWindowUpdate32(st, pad)
-		}
+		// Call sendWindowUpdate even if there is no padding,
+		// to return buffered flow control credit if the sent
+		// window has shrunk.
+		pad := int32(f.Length) - int32(len(data))
+		sc.sendWindowUpdate32(nil, pad)
+		sc.sendWindowUpdate32(st, pad)
 	}
 	if f.StreamEnded() {
 		st.endStream()
@@ -2105,8 +2100,7 @@ func (sc *serverConn) newStream(id, pusherID uint32, state streamState) *stream
 	st.cw.Init()
 	st.flow.conn = &sc.flow // link to conn-level counter
 	st.flow.add(sc.initialStreamSendWindowSize)
-	st.inflow.conn = &sc.inflow // link to conn-level counter
-	st.inflow.add(sc.srv.initialStreamRecvWindowSize())
+	st.inflow.init(sc.srv.initialStreamRecvWindowSize())
 	if sc.hs.WriteTimeout != 0 {
 		st.writeDeadline = time.AfterFunc(sc.hs.WriteTimeout, st.onWriteTimeout)
 	}
@@ -2388,47 +2382,28 @@ func (sc *serverConn) noteBodyRead(st *stream, n int) {
 }
 
 // st may be nil for conn-level
-func (sc *serverConn) sendWindowUpdate(st *stream, n int) {
-	sc.serveG.check()
-	// "The legal range for the increment to the flow control
-	// window is 1 to 2^31-1 (2,147,483,647) octets."
-	// A Go Read call on 64-bit machines could in theory read
-	// a larger Read than this. Very unlikely, but we handle it here
-	// rather than elsewhere for now.
-	const maxUint31 = 1<<31 - 1
-	for n > maxUint31 {
-		sc.sendWindowUpdate32(st, maxUint31)
-		n -= maxUint31
-	}
-	sc.sendWindowUpdate32(st, int32(n))
+func (sc *serverConn) sendWindowUpdate32(st *stream, n int32) {
+	sc.sendWindowUpdate(st, int(n))
 }
 
 // st may be nil for conn-level
-func (sc *serverConn) sendWindowUpdate32(st *stream, n int32) {
+func (sc *serverConn) sendWindowUpdate(st *stream, n int) {
 	sc.serveG.check()
-	if n == 0 {
-		return
-	}
-	if n < 0 {
-		panic("negative update")
-	}
 	var streamID uint32
-	if st != nil {
+	var send int32
+	if st == nil {
+		send = sc.inflow.add(n)
+	} else {
 		streamID = st.id
+		send = st.inflow.add(n)
+	}
+	if send == 0 {
+		return
 	}
 	sc.writeFrame(FrameWriteRequest{
-		write:  writeWindowUpdate{streamID: streamID, n: uint32(n)},
+		write:  writeWindowUpdate{streamID: streamID, n: uint32(send)},
 		stream: st,
 	})
-	var ok bool
-	if st == nil {
-		ok = sc.inflow.add(n)
-	} else {
-		ok = st.inflow.add(n)
-	}
-	if !ok {
-		panic("internal error; sent too many window updates without decrements?")
-	}
 }
 
 // requestBody is the Handler's Request.Body type.
diff --git a/vendor/golang.org/x/net/http2/transport.go b/vendor/golang.org/x/net/http2/transport.go
index 30f706e6c..b43ec10cf 100644
--- a/vendor/golang.org/x/net/http2/transport.go
+++ b/vendor/golang.org/x/net/http2/transport.go
@@ -47,10 +47,6 @@ const (
 	// we buffer per stream.
 	transportDefaultStreamFlow = 4 << 20
 
-	// transportDefaultStreamMinRefresh is the minimum number of bytes we'll send
-	// a stream-level WINDOW_UPDATE for at a time.
-	transportDefaultStreamMinRefresh = 4 << 10
-
 	defaultUserAgent = "Go-http-client/2.0"
 
 	// initialMaxConcurrentStreams is a connections maxConcurrentStreams until
@@ -310,8 +306,8 @@ type ClientConn struct {
 
 	mu              sync.Mutex // guards following
 	cond            *sync.Cond // hold mu; broadcast on flow/closed changes
-	flow            flow       // our conn-level flow control quota (cs.flow is per stream)
-	inflow          flow       // peer's conn-level flow control
+	flow            outflow    // our conn-level flow control quota (cs.outflow is per stream)
+	inflow          inflow     // peer's conn-level flow control
 	doNotReuse      bool       // whether conn is marked to not be reused for any future requests
 	closing         bool
 	closed          bool
@@ -376,10 +372,10 @@ type clientStream struct {
 	respHeaderRecv chan struct{}  // closed when headers are received
 	res            *http.Response // set if respHeaderRecv is closed
 
-	flow        flow  // guarded by cc.mu
-	inflow      flow  // guarded by cc.mu
-	bytesRemain int64 // -1 means unknown; owned by transportResponseBody.Read
-	readErr     error // sticky read error; owned by transportResponseBody.Read
+	flow        outflow // guarded by cc.mu
+	inflow      inflow  // guarded by cc.mu
+	bytesRemain int64   // -1 means unknown; owned by transportResponseBody.Read
+	readErr     error   // sticky read error; owned by transportResponseBody.Read
 
 	reqBody              io.ReadCloser
 	reqBodyContentLength int64         // -1 means unknown
@@ -811,7 +807,7 @@ func (t *Transport) newClientConn(c net.Conn, singleUse bool) (*ClientConn, erro
 	cc.bw.Write(clientPreface)
 	cc.fr.WriteSettings(initialSettings...)
 	cc.fr.WriteWindowUpdate(0, transportDefaultConnFlow)
-	cc.inflow.add(transportDefaultConnFlow + initialWindowSize)
+	cc.inflow.init(transportDefaultConnFlow + initialWindowSize)
 	cc.bw.Flush()
 	if cc.werr != nil {
 		cc.Close()
@@ -2073,8 +2069,7 @@ type resAndError struct {
 func (cc *ClientConn) addStreamLocked(cs *clientStream) {
 	cs.flow.add(int32(cc.initialWindowSize))
 	cs.flow.setConnFlow(&cc.flow)
-	cs.inflow.add(transportDefaultStreamFlow)
-	cs.inflow.setConnFlow(&cc.inflow)
+	cs.inflow.init(transportDefaultStreamFlow)
 	cs.ID = cc.nextStreamID
 	cc.nextStreamID += 2
 	cc.streams[cs.ID] = cs
@@ -2533,21 +2528,10 @@ func (b transportResponseBody) Read(p []byte) (n int, err error) {
 	}
 
 	cc.mu.Lock()
-	var connAdd, streamAdd int32
-	// Check the conn-level first, before the stream-level.
-	if v := cc.inflow.available(); v < transportDefaultConnFlow/2 {
-		connAdd = transportDefaultConnFlow - v
-		cc.inflow.add(connAdd)
-	}
+	connAdd := cc.inflow.add(n)
+	var streamAdd int32
 	if err == nil { // No need to refresh if the stream is over or failed.
-		// Consider any buffered body data (read from the conn but not
-		// consumed by the client) when computing flow control for this
-		// stream.
-		v := int(cs.inflow.available()) + cs.bufPipe.Len()
-		if v < transportDefaultStreamFlow-transportDefaultStreamMinRefresh {
-			streamAdd = int32(transportDefaultStreamFlow - v)
-			cs.inflow.add(streamAdd)
-		}
+		streamAdd = cs.inflow.add(n)
 	}
 	cc.mu.Unlock()
 
@@ -2575,17 +2559,15 @@ func (b transportResponseBody) Close() error {
 	if unread > 0 {
 		cc.mu.Lock()
 		// Return connection-level flow control.
-		if unread > 0 {
-			cc.inflow.add(int32(unread))
-		}
+		connAdd := cc.inflow.add(unread)
 		cc.mu.Unlock()
 
 		// TODO(dneil): Acquiring this mutex can block indefinitely.
 		// Move flow control return to a goroutine?
 		cc.wmu.Lock()
 		// Return connection-level flow control.
-		if unread > 0 {
-			cc.fr.WriteWindowUpdate(0, uint32(unread))
+		if connAdd > 0 {
+			cc.fr.WriteWindowUpdate(0, uint32(connAdd))
 		}
 		cc.bw.Flush()
 		cc.wmu.Unlock()
@@ -2628,13 +2610,18 @@ func (rl *clientConnReadLoop) processData(f *DataFrame) error {
 		// But at least return their flow control:
 		if f.Length > 0 {
 			cc.mu.Lock()
-			cc.inflow.add(int32(f.Length))
+			ok := cc.inflow.take(f.Length)
+			connAdd := cc.inflow.add(int(f.Length))
 			cc.mu.Unlock()
-
-			cc.wmu.Lock()
-			cc.fr.WriteWindowUpdate(0, uint32(f.Length))
-			cc.bw.Flush()
-			cc.wmu.Unlock()
+			if !ok {
+				return ConnectionError(ErrCodeFlowControl)
+			}
+			if connAdd > 0 {
+				cc.wmu.Lock()
+				cc.fr.WriteWindowUpdate(0, uint32(connAdd))
+				cc.bw.Flush()
+				cc.wmu.Unlock()
+			}
 		}
 		return nil
 	}
@@ -2665,9 +2652,7 @@ func (rl *clientConnReadLoop) processData(f *DataFrame) error {
 		}
 		// Check connection-level flow control.
 		cc.mu.Lock()
-		if cs.inflow.available() >= int32(f.Length) {
-			cs.inflow.take(int32(f.Length))
-		} else {
+		if !takeInflows(&cc.inflow, &cs.inflow, f.Length) {
 			cc.mu.Unlock()
 			return ConnectionError(ErrCodeFlowControl)
 		}
@@ -2689,19 +2674,20 @@ func (rl *clientConnReadLoop) processData(f *DataFrame) error {
 			}
 		}
 
-		if refund > 0 {
-			cc.inflow.add(int32(refund))
-			if !didReset {
-				cs.inflow.add(int32(refund))
-			}
+		sendConn := cc.inflow.add(refund)
+		var sendStream int32
+		if !didReset {
+			sendStream = cs.inflow.add(refund)
 		}
 		cc.mu.Unlock()
 
-		if refund > 0 {
+		if sendConn > 0 || sendStream > 0 {
 			cc.wmu.Lock()
-			cc.fr.WriteWindowUpdate(0, uint32(refund))
-			if !didReset {
-				cc.fr.WriteWindowUpdate(cs.ID, uint32(refund))
+			if sendConn > 0 {
+				cc.fr.WriteWindowUpdate(0, uint32(sendConn))
+			}
+			if sendStream > 0 {
+				cc.fr.WriteWindowUpdate(cs.ID, uint32(sendStream))
 			}
 			cc.bw.Flush()
 			cc.wmu.Unlock()