vendor: add d2g/dhcp4server

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

@@ -0,0 +1,59 @@
+// 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.
+
+package ipv4
+
+import (
+	"encoding/binary"
+	"errors"
+	"net"
+	"unsafe"
+)
+
+var (
+	errMissingAddress           = errors.New("missing address")
+	errMissingHeader            = errors.New("missing header")
+	errHeaderTooShort           = errors.New("header too short")
+	errBufferTooShort           = errors.New("buffer too short")
+	errInvalidConnType          = errors.New("invalid conn type")
+	errOpNoSupport              = errors.New("operation not supported")
+	errNoSuchInterface          = errors.New("no such interface")
+	errNoSuchMulticastInterface = errors.New("no such multicast interface")
+
+	// See http://www.freebsd.org/doc/en/books/porters-handbook/freebsd-versions.html.
+	freebsdVersion uint32
+
+	nativeEndian binary.ByteOrder
+)
+
+func init() {
+	i := uint32(1)
+	b := (*[4]byte)(unsafe.Pointer(&i))
+	if b[0] == 1 {
+		nativeEndian = binary.LittleEndian
+	} else {
+		nativeEndian = binary.BigEndian
+	}
+}
+
+func boolint(b bool) int {
+	if b {
+		return 1
+	}
+	return 0
+}
+
+func netAddrToIP4(a net.Addr) net.IP {
+	switch v := a.(type) {
+	case *net.UDPAddr:
+		if ip := v.IP.To4(); ip != nil {
+			return ip
+		}
+	case *net.IPAddr:
+		if ip := v.IP.To4(); ip != nil {
+			return ip
+		}
+	}
+	return nil
+}