From: Jason A. Donenfeld <Jason@zx2c4.com>
Date: Wed, 26 Jun 2019 11:27:48 +0000 (+0200)
Subject: tun: windows: inform wintun of maximum buffer length for writes
X-Git-Tag: 0.0.20190805~33
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5e6eff81b6f7f18b3dd24bec03ea71f009a3e938;p=thirdparty%2Fwireguard-go.git

tun: windows: inform wintun of maximum buffer length for writes
---

diff --git a/tun/tun_windows.go b/tun/tun_windows.go
index 05fc3df..1de74e6 100644
--- a/tun/tun_windows.go
+++ b/tun/tun_windows.go
@@ -141,6 +141,12 @@ func (tun *NativeTun) openTUN() error {
 			}
 			return err
 		}
+		firstSize := (*uint32)(unsafe.Pointer(&tun.wrBuff.data[0]))
+		saved := *firstSize
+		*firstSize = 0
+		// Set the maximum buffer length with an invalid write.
+		tun.tunFileWrite.Write(tun.wrBuff.data[:])
+		*firstSize = saved
 	}
 	return nil
 }