vendor: add d2g/dhcp4server

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

@@ -0,0 +1,26 @@
+// Copyright 2014 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,!386 netbsd openbsd
+
+package ipv4
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+func getsockopt(fd, level, name int, v unsafe.Pointer, l *uint32) error {
+	if _, _, errno := syscall.Syscall6(syscall.SYS_GETSOCKOPT, uintptr(fd), uintptr(level), uintptr(name), uintptr(v), uintptr(unsafe.Pointer(l)), 0); errno != 0 {
+		return error(errno)
+	}
+	return nil
+}
+
+func setsockopt(fd, level, name int, v unsafe.Pointer, l uint32) error {
+	if _, _, errno := syscall.Syscall6(syscall.SYS_SETSOCKOPT, uintptr(fd), uintptr(level), uintptr(name), uintptr(v), uintptr(l), 0); errno != 0 {
+		return error(errno)
+	}
+	return nil
+}