quic: check for packet overflow when writing MAX_STREAMS

Return a bool from remoteStreamLimits.appendFrame indicating
whether the packet had space for all appended frames,
matching the pattern of other functions that write frames.

For golang/go#58547

Change-Id: If21d1b192cea210b94a0c6ce996a73fe43b3babe
Reviewed-on: https://go-review.googlesource.com/c/net/+/526755
Reviewed-by: Jonathan Amsterdam <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: neild

internal/quic/conn_streams.go

@@ -212,8 +212,14 @@ func (c *Conn) queueStreamForSend(s *Stream) {
 // It returns true if no more frames need appending,
 // false if not everything fit in the current packet.
 func (c *Conn) appendStreamFrames(w *packetWriter, pnum packetNumber, pto bool) bool {
-	c.streams.remoteLimit[uniStream].appendFrame(w, uniStream, pnum, pto)
-	c.streams.remoteLimit[bidiStream].appendFrame(w, bidiStream, pnum, pto)
+	// MAX_STREAM_DATA
+	if !c.streams.remoteLimit[uniStream].appendFrame(w, uniStream, pnum, pto) {
+		return false
+	}
+	if !c.streams.remoteLimit[bidiStream].appendFrame(w, bidiStream, pnum, pto) {
+		return false
+	}
+
 	if pto {
 		return c.appendStreamFramesPTO(w, pnum)
 	}

internal/quic/stream_limits.go

@@ -98,12 +98,16 @@ func (lim *remoteStreamLimits) maybeUpdateMax() {
 	}
 }
 
-// appendFrame appends a MAX_DATA frame if necessary.
-func (lim *remoteStreamLimits) appendFrame(w *packetWriter, typ streamType, pnum packetNumber, pto bool) {
-	if !lim.sendMax.shouldSendPTO(pto) {
-		return
-	}
-	if w.appendMaxStreamsFrame(typ, lim.max) {
+// appendFrame appends a MAX_STREAMS frame to the current packet, if necessary.
+//
+// It returns true if no more frames need appending,
+// false if not everything fit in the current packet.
+func (lim *remoteStreamLimits) appendFrame(w *packetWriter, typ streamType, pnum packetNumber, pto bool) bool {
+	if lim.sendMax.shouldSendPTO(pto) {
+		if !w.appendMaxStreamsFrame(typ, lim.max) {
+			return false
+		}
 		lim.sendMax.setSent(pnum)
 	}
+	return true
 }