Move presence methods from segment to TCPFlags

PiperOrigin-RevId: 376001032

6 files changed, 29 insertions, 39 deletions

diff --git a/pkg/tcpip/transport/tcp/accept.go b/pkg/tcpip/transport/tcp/accept.go
index 4a33fbc24..db75228a1 100644
--- a/pkg/tcpip/transport/tcp/accept.go
+++ b/pkg/tcpip/transport/tcp/accept.go
@@ -550,7 +550,7 @@ func (e *endpoint) handleListenSegment(ctx *listenContext, s *segment) tcpip.Err
 	e.rcvQueueInfo.rcvQueueMu.Lock()
 	rcvClosed := e.rcvQueueInfo.RcvClosed
 	e.rcvQueueInfo.rcvQueueMu.Unlock()
-	if rcvClosed || s.flagsAreSet(header.TCPFlagSyn|header.TCPFlagAck) {
+	if rcvClosed || s.flags.Contains(header.TCPFlagSyn|header.TCPFlagAck) {
 		// If the endpoint is shutdown, reply with reset.
 		//
 		// RFC 793 section 3.4 page 35 (figure 12) outlines that a RST
diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go
index 2fcdf1cda..08849d0cc 100644
--- a/pkg/tcpip/transport/tcp/connect.go
+++ b/pkg/tcpip/transport/tcp/connect.go
@@ -212,7 +212,7 @@ func (h *handshake) resetToSynRcvd(iss seqnum.Value, irs seqnum.Value, opts *hea
 // a TCP 3-way handshake is valid. If it's not, a RST segment is sent back in
 // response.
 func (h *handshake) checkAck(s *segment) bool {
-	if s.flagIsSet(header.TCPFlagAck) && s.ackNumber != h.iss+1 {
+	if s.flags.Contains(header.TCPFlagAck) && s.ackNumber != h.iss+1 {
 		// RFC 793, page 36, states that a reset must be generated when
 		// the connection is in any non-synchronized state and an
 		// incoming segment acknowledges something not yet sent. The
@@ -230,8 +230,8 @@ func (h *handshake) checkAck(s *segment) bool {
 func (h *handshake) synSentState(s *segment) tcpip.Error {
 	// RFC 793, page 37, states that in the SYN-SENT state, a reset is
 	// acceptable if the ack field acknowledges the SYN.
-	if s.flagIsSet(header.TCPFlagRst) {
-		if s.flagIsSet(header.TCPFlagAck) && s.ackNumber == h.iss+1 {
+	if s.flags.Contains(header.TCPFlagRst) {
+		if s.flags.Contains(header.TCPFlagAck) && s.ackNumber == h.iss+1 {
 			// RFC 793, page 67, states that "If the RST bit is set [and] If the ACK
 			// was acceptable then signal the user "error: connection reset", drop
 			// the segment, enter CLOSED state, delete TCB, and return."
@@ -249,7 +249,7 @@ func (h *handshake) synSentState(s *segment) tcpip.Error {
 
 	// We are in the SYN-SENT state. We only care about segments that have
 	// the SYN flag.
-	if !s.flagIsSet(header.TCPFlagSyn) {
+	if !s.flags.Contains(header.TCPFlagSyn) {
 		return nil
 	}
 
@@ -270,7 +270,7 @@ func (h *handshake) synSentState(s *segment) tcpip.Error {
 
 	// If this is a SYN ACK response, we only need to acknowledge the SYN
 	// and the handshake is completed.
-	if s.flagIsSet(header.TCPFlagAck) {
+	if s.flags.Contains(header.TCPFlagAck) {
 		h.state = handshakeCompleted
 
 		h.ep.transitionToStateEstablishedLocked(h)
@@ -316,7 +316,7 @@ func (h *handshake) synSentState(s *segment) tcpip.Error {
 // synRcvdState handles a segment received when the TCP 3-way handshake is in
 // the SYN-RCVD state.
 func (h *handshake) synRcvdState(s *segment) tcpip.Error {
-	if s.flagIsSet(header.TCPFlagRst) {
+	if s.flags.Contains(header.TCPFlagRst) {
 		// RFC 793, page 37, states that in the SYN-RCVD state, a reset
 		// is acceptable if the sequence number is in the window.
 		if s.sequenceNumber.InWindow(h.ackNum, h.rcvWnd) {
@@ -340,13 +340,13 @@ func (h *handshake) synRcvdState(s *segment) tcpip.Error {
 		return nil
 	}
 
-	if s.flagIsSet(header.TCPFlagSyn) && s.sequenceNumber != h.ackNum-1 {
+	if s.flags.Contains(header.TCPFlagSyn) && s.sequenceNumber != h.ackNum-1 {
 		// We received two SYN segments with different sequence
 		// numbers, so we reset this and restart the whole
 		// process, except that we don't reset the timer.
 		ack := s.sequenceNumber.Add(s.logicalLen())
 		seq := seqnum.Value(0)
-		if s.flagIsSet(header.TCPFlagAck) {
+		if s.flags.Contains(header.TCPFlagAck) {
 			seq = s.ackNumber
 		}
 		h.ep.sendRaw(buffer.VectorisedView{}, header.TCPFlagRst|header.TCPFlagAck, seq, ack, 0)
@@ -378,7 +378,7 @@ func (h *handshake) synRcvdState(s *segment) tcpip.Error {
 
 	// We have previously received (and acknowledged) the peer's SYN. If the
 	// peer acknowledges our SYN, the handshake is completed.
-	if s.flagIsSet(header.TCPFlagAck) {
+	if s.flags.Contains(header.TCPFlagAck) {
 		// If deferAccept is not zero and this is a bare ACK and the
 		// timeout is not hit then drop the ACK.
 		if h.deferAccept != 0 && s.data.Size() == 0 && h.ep.stack.Clock().NowMonotonic().Sub(h.startTime) < h.deferAccept {
@@ -426,7 +426,7 @@ func (h *handshake) synRcvdState(s *segment) tcpip.Error {
 
 func (h *handshake) handleSegment(s *segment) tcpip.Error {
 	h.sndWnd = s.window
-	if !s.flagIsSet(header.TCPFlagSyn) && h.sndWndScale > 0 {
+	if !s.flags.Contains(header.TCPFlagSyn) && h.sndWndScale > 0 {
 		h.sndWnd <<= uint8(h.sndWndScale)
 	}
 
@@ -634,7 +634,7 @@ func (bt *backoffTimer) stop() {
 }
 
 func parseSynSegmentOptions(s *segment) header.TCPSynOptions {
-	synOpts := header.ParseSynOptions(s.options, s.flagIsSet(header.TCPFlagAck))
+	synOpts := header.ParseSynOptions(s.options, s.flags.Contains(header.TCPFlagAck))
 	if synOpts.TS {
 		s.parsedOptions.TSVal = synOpts.TSVal
 		s.parsedOptions.TSEcr = synOpts.TSEcr
@@ -1188,11 +1188,11 @@ func (e *endpoint) handleSegmentLocked(s *segment) (cont bool, err tcpip.Error)
 	// the TCPEndpointState after the segment is processed.
 	defer e.probeSegmentLocked()
 
-	if s.flagIsSet(header.TCPFlagRst) {
+	if s.flags.Contains(header.TCPFlagRst) {
 		if ok, err := e.handleReset(s); !ok {
 			return false, err
 		}
-	} else if s.flagIsSet(header.TCPFlagSyn) {
+	} else if s.flags.Contains(header.TCPFlagSyn) {
 		// See: https://tools.ietf.org/html/rfc5961#section-4.1
 		//   1) If the SYN bit is set, irrespective of the sequence number, TCP
 		//    MUST send an ACK (also referred to as challenge ACK) to the remote
@@ -1216,7 +1216,7 @@ func (e *endpoint) handleSegmentLocked(s *segment) (cont bool, err tcpip.Error)
 		// should then rely on SYN retransmission from the remote end to
 		// re-establish the connection.
 		e.snd.maybeSendOutOfWindowAck(s)
-	} else if s.flagIsSet(header.TCPFlagAck) {
+	} else if s.flags.Contains(header.TCPFlagAck) {
 		// Patch the window size in the segment according to the
 		// send window scale.
 		s.window <<= e.snd.SndWndScale
diff --git a/pkg/tcpip/transport/tcp/protocol.go b/pkg/tcpip/transport/tcp/protocol.go
index c970dcecc..7c38ad480 100644
--- a/pkg/tcpip/transport/tcp/protocol.go
+++ b/pkg/tcpip/transport/tcp/protocol.go
@@ -149,7 +149,7 @@ func (p *protocol) HandleUnknownDestinationPacket(id stack.TransportEndpointID,
 		return stack.UnknownDestinationPacketMalformed
 	}
 
-	if !s.flagIsSet(header.TCPFlagRst) {
+	if !s.flags.Contains(header.TCPFlagRst) {
 		replyWithReset(p.stack, s, stack.DefaultTOS, 0)
 	}
 
@@ -181,7 +181,7 @@ func replyWithReset(st *stack.Stack, s *segment, tos, ttl uint8) tcpip.Error {
 	//   reset has sequence number zero and the ACK field is set to the sum
 	//   of the sequence number and segment length of the incoming segment.
 	//   The connection remains in the CLOSED state.
-	if s.flagIsSet(header.TCPFlagAck) {
+	if s.flags.Contains(header.TCPFlagAck) {
 		seq = s.ackNumber
 	} else {
 		flags |= header.TCPFlagAck
diff --git a/pkg/tcpip/transport/tcp/rcv.go b/pkg/tcpip/transport/tcp/rcv.go
index b46f8320e..661ca604a 100644
--- a/pkg/tcpip/transport/tcp/rcv.go
+++ b/pkg/tcpip/transport/tcp/rcv.go
@@ -244,7 +244,7 @@ func (r *receiver) consumeSegment(s *segment, segSeq seqnum.Value, segLen seqnum
 	TrimSACKBlockList(&r.ep.sack, r.RcvNxt)
 
 	// Handle FIN or FIN-ACK.
-	if s.flagIsSet(header.TCPFlagFin) {
+	if s.flags.Contains(header.TCPFlagFin) {
 		r.RcvNxt++
 
 		// Send ACK immediately.
@@ -260,7 +260,7 @@ func (r *receiver) consumeSegment(s *segment, segSeq seqnum.Value, segLen seqnum
 		case StateEstablished:
 			r.ep.setEndpointState(StateCloseWait)
 		case StateFinWait1:
-			if s.flagIsSet(header.TCPFlagAck) && s.ackNumber == r.ep.snd.SndNxt {
+			if s.flags.Contains(header.TCPFlagAck) && s.ackNumber == r.ep.snd.SndNxt {
 				// FIN-ACK, transition to TIME-WAIT.
 				r.ep.setEndpointState(StateTimeWait)
 			} else {
@@ -295,7 +295,7 @@ func (r *receiver) consumeSegment(s *segment, segSeq seqnum.Value, segLen seqnum
 
 	// Handle ACK (not FIN-ACK, which we handled above) during one of the
 	// shutdown states.
-	if s.flagIsSet(header.TCPFlagAck) && s.ackNumber == r.ep.snd.SndNxt {
+	if s.flags.Contains(header.TCPFlagAck) && s.ackNumber == r.ep.snd.SndNxt {
 		switch r.ep.EndpointState() {
 		case StateFinWait1:
 			r.ep.setEndpointState(StateFinWait2)
@@ -423,7 +423,7 @@ func (r *receiver) handleRcvdSegmentClosing(s *segment, state EndpointState, clo
 		// while the FIN is considered to occur after
 		// the last actual data octet in a segment in
 		// which it occurs.
-		if closed && (!s.flagIsSet(header.TCPFlagFin) || s.sequenceNumber.Add(s.logicalLen()) != r.RcvNxt+1) {
+		if closed && (!s.flags.Contains(header.TCPFlagFin) || s.sequenceNumber.Add(s.logicalLen()) != r.RcvNxt+1) {
 			return true, &tcpip.ErrConnectionAborted{}
 		}
 	}
@@ -470,7 +470,7 @@ func (r *receiver) handleRcvdSegment(s *segment) (drop bool, err tcpip.Error) {
 
 	// Defer segment processing if it can't be consumed now.
 	if !r.consumeSegment(s, segSeq, segLen) {
-		if segLen > 0 || s.flagIsSet(header.TCPFlagFin) {
+		if segLen > 0 || s.flags.Contains(header.TCPFlagFin) {
 			// We only store the segment if it's within our buffer size limit.
 			//
 			// Only use 75% of the receive buffer queue for out-of-order
@@ -538,7 +538,7 @@ func (r *receiver) handleTimeWaitSegment(s *segment) (resetTimeWait bool, newSyn
 	//
 	// As we do not yet support PAWS, we are being conservative in ignoring
 	// RSTs by default.
-	if s.flagIsSet(header.TCPFlagRst) {
+	if s.flags.Contains(header.TCPFlagRst) {
 		return false, false
 	}
 
@@ -558,13 +558,13 @@ func (r *receiver) handleTimeWaitSegment(s *segment) (resetTimeWait bool, newSyn
 
 	//    (2) returns to TIME-WAIT state if the SYN turns out
 	//      to be an old duplicate".
-	if s.flagIsSet(header.TCPFlagSyn) && r.RcvNxt.LessThan(segSeq) {
+	if s.flags.Contains(header.TCPFlagSyn) && r.RcvNxt.LessThan(segSeq) {
 
 		return false, true
 	}
 
 	// Drop the segment if it does not contain an ACK.
-	if !s.flagIsSet(header.TCPFlagAck) {
+	if !s.flags.Contains(header.TCPFlagAck) {
 		return false, false
 	}
 
@@ -573,7 +573,7 @@ func (r *receiver) handleTimeWaitSegment(s *segment) (resetTimeWait bool, newSyn
 		r.ep.updateRecentTimestamp(s.parsedOptions.TSVal, r.ep.snd.MaxSentAck, segSeq)
 	}
 
-	if segSeq.Add(1) == r.RcvNxt && s.flagIsSet(header.TCPFlagFin) {
+	if segSeq.Add(1) == r.RcvNxt && s.flags.Contains(header.TCPFlagFin) {
 		// If it's a FIN-ACK then resetTimeWait and send an ACK, as it
 		// indicates our final ACK could have been lost.
 		r.ep.snd.sendAck()
diff --git a/pkg/tcpip/transport/tcp/segment.go b/pkg/tcpip/transport/tcp/segment.go
index e5c0d52fa..ca78c96f2 100644
--- a/pkg/tcpip/transport/tcp/segment.go
+++ b/pkg/tcpip/transport/tcp/segment.go
@@ -148,16 +148,6 @@ func (s *segment) merge(oth *segment) {
 	oth.dataMemSize = oth.data.Size()
 }
 
-// flagIsSet checks if at least one flag in flags is set in s.flags.
-func (s *segment) flagIsSet(flags header.TCPFlags) bool {
-	return s.flags&flags != 0
-}
-
-// flagsAreSet checks if all flags in flags are set in s.flags.
-func (s *segment) flagsAreSet(flags header.TCPFlags) bool {
-	return s.flags&flags == flags
-}
-
 // setOwner sets the owning endpoint for this segment. Its required
 // to be called to ensure memory accounting for receive/send buffer
 // queues is done properly.
@@ -197,10 +187,10 @@ func (s *segment) incRef() {
 // as the data length plus one for each of the SYN and FIN bits set.
 func (s *segment) logicalLen() seqnum.Size {
 	l := seqnum.Size(s.data.Size())
-	if s.flagIsSet(header.TCPFlagSyn) {
+	if s.flags.Contains(header.TCPFlagSyn) {
 		l++
 	}
-	if s.flagIsSet(header.TCPFlagFin) {
+	if s.flags.Contains(header.TCPFlagFin) {
 		l++
 	}
 	return l
diff --git a/pkg/tcpip/transport/tcp/snd.go b/pkg/tcpip/transport/tcp/snd.go
index ccff9ca8d..72d58dcff 100644
--- a/pkg/tcpip/transport/tcp/snd.go
+++ b/pkg/tcpip/transport/tcp/snd.go
@@ -1132,7 +1132,7 @@ func (s *sender) isDupAck(seg *segment) bool {
 		// (b) The incoming acknowledgment carries no data.
 		seg.logicalLen() == 0 &&
 		// (c) The SYN and FIN bits are both off.
-		!seg.flagIsSet(header.TCPFlagFin) && !seg.flagIsSet(header.TCPFlagSyn) &&
+		!seg.flags.Intersects(header.TCPFlagFin|header.TCPFlagSyn) &&
 		// (d) the ACK number is equal to the greatest acknowledgment received on
 		// the given connection (TCP.UNA from RFC793).
 		seg.ackNumber == s.SndUna &&