From 8e22d7137a9d46ce48ede098414b425c842e78b3 Mon Sep 17 00:00:00 2001
From: Arceliar <Arceliar@users.noreply.github.com>
Date: Sat, 5 Oct 2019 10:47:15 -0500
Subject: [PATCH] use bbr congestion control on linux, note that we're not
 doing anything intelligent with the errors right now if setting it fails

---
 src/yggdrasil/tcp_linux.go | 28 ++++++++++++++++++++++++++++
 src/yggdrasil/tcp_other.go |  2 +-
 2 files changed, 29 insertions(+), 1 deletion(-)
 create mode 100644 src/yggdrasil/tcp_linux.go

diff --git a/src/yggdrasil/tcp_linux.go b/src/yggdrasil/tcp_linux.go
new file mode 100644
index 00000000..d957ceba
--- /dev/null
+++ b/src/yggdrasil/tcp_linux.go
@@ -0,0 +1,28 @@
+// +build linux
+
+package yggdrasil
+
+import (
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+// WARNING: This context is used both by net.Dialer and net.Listen in tcp.go
+
+func (t *tcp) tcpContext(network, address string, c syscall.RawConn) error {
+	var control error
+	var bbr error
+
+	control = c.Control(func(fd uintptr) {
+		// sys/socket.h: #define	SO_RECV_ANYIF	0x1104
+		bbr = unix.SetsockoptString(int(fd), unix.IPPROTO_TCP, unix.TCP_CONGESTION, "bbr")
+	})
+
+	switch {
+	case bbr != nil:
+		return bbr
+	default:
+		return control
+	}
+}
diff --git a/src/yggdrasil/tcp_other.go b/src/yggdrasil/tcp_other.go
index 47bd772c..44c3d76d 100644
--- a/src/yggdrasil/tcp_other.go
+++ b/src/yggdrasil/tcp_other.go
@@ -1,4 +1,4 @@
-// +build !darwin
+// +build !darwin,!linux
 
 package yggdrasil