From 085c7033cd3bf7f2609aa53699813a2937573539 Mon Sep 17 00:00:00 2001
From: ddirect <62487612+ddirect@users.noreply.github.com>
Date: Mon, 9 Feb 2026 02:24:24 +0200
Subject: [PATCH] TCP: advertising the currently available window size (#35)

---
 tcp/handler.go | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tcp/handler.go b/tcp/handler.go
index ac9f2d4..4f90db9 100644
--- a/tcp/handler.go
+++ b/tcp/handler.go
@@ -255,6 +255,7 @@ func (h *Handler) Send(b []byte) (int, error) {
 		var ok bool
 		available := min(buffered, len(b)-sizeHeaderTCP)
 		segment, ok = h.scb.PendingSegment(available)
+		segment.WND = Size(h.bufRx.Free())
 		if !ok {
 			// No pending control segment or data to send. Yield.
 			return 0, nil