From: Jason A. Donenfeld <Jason@zx2c4.com>
Date: Fri, 9 Apr 2021 00:17:59 +0000 (-0600)
Subject: conn: windows: compare head and tail properly
X-Git-Tag: 0.0.20210424~11
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=75526d60714ce2e2e967830b42422788fb1b7498;p=thirdparty%2Fwireguard-go.git

conn: windows: compare head and tail properly

By not comparing these with the modulo, the ring became nearly never
full, resulting in completion queue buffers filling up prematurely.

Reported-by: Joshua Sjoding <joshua.sjoding@scjalliance.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---

diff --git a/conn/bind_windows.go b/conn/bind_windows.go
index 6cabee1..a25c7aa 100644
--- a/conn/bind_windows.go
+++ b/conn/bind_windows.go
@@ -47,7 +47,7 @@ func (rb *ringBuffer) Push() *ringPacket {
 	}
 	ret := (*ringPacket)(unsafe.Pointer(rb.packets + (uintptr(rb.tail%packetsPerRing) * unsafe.Sizeof(ringPacket{}))))
 	rb.tail += 1
-	if rb.tail == rb.head {
+	if rb.tail%packetsPerRing == rb.head%packetsPerRing {
 		rb.isFull = true
 	}
 	return ret