lib/connections: Support setting traffic class (fixes #3790)

vendor/golang.org/x/net/ipv4/genericopt_posix.go

@@ -0,0 +1,63 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd linux netbsd openbsd solaris windows
+
+package ipv4
+
+import (
+	"syscall"
+
+	"golang.org/x/net/internal/netreflect"
+)
+
+// TOS returns the type-of-service field value for outgoing packets.
+func (c *genericOpt) TOS() (int, error) {
+	if !c.ok() {
+		return 0, syscall.EINVAL
+	}
+	s, err := netreflect.SocketOf(c.Conn)
+	if err != nil {
+		return 0, err
+	}
+	return getInt(s, &sockOpts[ssoTOS])
+}
+
+// SetTOS sets the type-of-service field value for future outgoing
+// packets.
+func (c *genericOpt) SetTOS(tos int) error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	s, err := netreflect.SocketOf(c.Conn)
+	if err != nil {
+		return err
+	}
+	return setInt(s, &sockOpts[ssoTOS], tos)
+}
+
+// TTL returns the time-to-live field value for outgoing packets.
+func (c *genericOpt) TTL() (int, error) {
+	if !c.ok() {
+		return 0, syscall.EINVAL
+	}
+	s, err := netreflect.SocketOf(c.Conn)
+	if err != nil {
+		return 0, err
+	}
+	return getInt(s, &sockOpts[ssoTTL])
+}
+
+// SetTTL sets the time-to-live field value for future outgoing
+// packets.
+func (c *genericOpt) SetTTL(ttl int) error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	s, err := netreflect.SocketOf(c.Conn)
+	if err != nil {
+		return err
+	}
+	return setInt(s, &sockOpts[ssoTTL], ttl)
+}