Change segment/pending queue to use receive buffer limits.

segment_queue today has its own standalone limit of MaxUnprocessedSegments but
this can be a problem in UnlockUser() we do not release the lock till there are
segments to be processed. What can happen is as handleSegments dequeues packets
more keep getting queued and we will never release the lock. This can keep
happening even if the receive buffer is full because nothing can read() till we
release the lock.

Further having a separate limit for pending segments makes it harder to track
memory usage etc. Unifying the limits makes it easier to reason about memory in
use and makes the overall buffer behaviour more consistent.

PiperOrigin-RevId: 333508122

1 files changed, 47 insertions, 13 deletions

diff --git a/pkg/tcpip/checker/checker.go b/pkg/tcpip/checker/checker.go
index b769094dc..19627fa9b 100644
--- a/pkg/tcpip/checker/checker.go
+++ b/pkg/tcpip/checker/checker.go
@@ -339,7 +339,7 @@ func NoChecksum(noChecksum bool) TransportChecker {
 
 		udp, ok := h.(header.UDP)
 		if !ok {
-			return
+			t.Fatalf("UDP header not found in h: %T", h)
 		}
 
 		if b := udp.Checksum() == 0; b != noChecksum {
@@ -348,14 +348,14 @@ func NoChecksum(noChecksum bool) TransportChecker {
 	}
 }
 
-// SeqNum creates a checker that checks the sequence number.
-func SeqNum(seq uint32) TransportChecker {
+// TCPSeqNum creates a checker that checks the sequence number.
+func TCPSeqNum(seq uint32) TransportChecker {
 	return func(t *testing.T, h header.Transport) {
 		t.Helper()
 
 		tcp, ok := h.(header.TCP)
 		if !ok {
-			return
+			t.Fatalf("TCP header not found in h: %T", h)
 		}
 
 		if s := tcp.SequenceNumber(); s != seq {
@@ -364,14 +364,14 @@ func SeqNum(seq uint32) TransportChecker {
 	}
 }
 
-// AckNum creates a checker that checks the ack number.
-func AckNum(seq uint32) TransportChecker {
+// TCPAckNum creates a checker that checks the ack number.
+func TCPAckNum(seq uint32) TransportChecker {
 	return func(t *testing.T, h header.Transport) {
 		t.Helper()
 
 		tcp, ok := h.(header.TCP)
 		if !ok {
-			return
+			t.Fatalf("TCP header not found in h: %T", h)
 		}
 
 		if s := tcp.AckNumber(); s != seq {
@@ -380,18 +380,52 @@ func AckNum(seq uint32) TransportChecker {
 	}
 }
 
-// Window creates a checker that checks the tcp window.
-func Window(window uint16) TransportChecker {
+// TCPWindow creates a checker that checks the tcp window.
+func TCPWindow(window uint16) TransportChecker {
 	return func(t *testing.T, h header.Transport) {
 		t.Helper()
 
 		tcp, ok := h.(header.TCP)
 		if !ok {
-			return
+			t.Fatalf("TCP header not found in hdr : %T", h)
 		}
 
 		if w := tcp.WindowSize(); w != window {
-			t.Errorf("Bad window, got 0x%x, want 0x%x", w, window)
+			t.Errorf("Bad window, got %d, want %d", w, window)
+		}
+	}
+}
+
+// TCPWindowGreaterThanEq creates a checker that checks that the TCP window
+// is greater than or equal to the provided value.
+func TCPWindowGreaterThanEq(window uint16) TransportChecker {
+	return func(t *testing.T, h header.Transport) {
+		t.Helper()
+
+		tcp, ok := h.(header.TCP)
+		if !ok {
+			t.Fatalf("TCP header not found in h: %T", h)
+		}
+
+		if w := tcp.WindowSize(); w < window {
+			t.Errorf("Bad window, got %d, want > %d", w, window)
+		}
+	}
+}
+
+// TCPWindowLessThanEq creates a checker that checks that the tcp window
+// is less than or equal to the provided value.
+func TCPWindowLessThanEq(window uint16) TransportChecker {
+	return func(t *testing.T, h header.Transport) {
+		t.Helper()
+
+		tcp, ok := h.(header.TCP)
+		if !ok {
+			t.Fatalf("TCP header not found in h: %T", h)
+		}
+
+		if w := tcp.WindowSize(); w > window {
+			t.Errorf("Bad window, got %d, want < %d", w, window)
 		}
 	}
 }
@@ -403,7 +437,7 @@ func TCPFlags(flags uint8) TransportChecker {
 
 		tcp, ok := h.(header.TCP)
 		if !ok {
-			return
+			t.Fatalf("TCP header not found in h: %T", h)
 		}
 
 		if f := tcp.Flags(); f != flags {
@@ -420,7 +454,7 @@ func TCPFlagsMatch(flags, mask uint8) TransportChecker {
 
 		tcp, ok := h.(header.TCP)
 		if !ok {
-			return
+			t.Fatalf("TCP header not found in h: %T", h)
 		}
 
 		if f := tcp.Flags(); (f & mask) != (flags & mask) {