Rework some things into packages (#489)

iputil/util.go

@@ -0,0 +1,66 @@
+package iputil
+
+import (
+	"encoding/binary"
+	"fmt"
+	"net"
+)
+
+type VpnIp uint32
+
+const maxIPv4StringLen = len("255.255.255.255")
+
+func (ip VpnIp) String() string {
+	b := make([]byte, maxIPv4StringLen)
+
+	n := ubtoa(b, 0, byte(ip>>24))
+	b[n] = '.'
+	n++
+
+	n += ubtoa(b, n, byte(ip>>16&255))
+	b[n] = '.'
+	n++
+
+	n += ubtoa(b, n, byte(ip>>8&255))
+	b[n] = '.'
+	n++
+
+	n += ubtoa(b, n, byte(ip&255))
+	return string(b[:n])
+}
+
+func (ip VpnIp) MarshalJSON() ([]byte, error) {
+	return []byte(fmt.Sprintf("\"%s\"", ip.String())), nil
+}
+
+func (ip VpnIp) ToIP() net.IP {
+	nip := make(net.IP, 4)
+	binary.BigEndian.PutUint32(nip, uint32(ip))
+	return nip
+}
+
+func Ip2VpnIp(ip []byte) VpnIp {
+	if len(ip) == 16 {
+		return VpnIp(binary.BigEndian.Uint32(ip[12:16]))
+	}
+	return VpnIp(binary.BigEndian.Uint32(ip))
+}
+
+// ubtoa encodes the string form of the integer v to dst[start:] and
+// returns the number of bytes written to dst. The caller must ensure
+// that dst has sufficient length.
+func ubtoa(dst []byte, start int, v byte) int {
+	if v < 10 {
+		dst[start] = v + '0'
+		return 1
+	} else if v < 100 {
+		dst[start+1] = v%10 + '0'
+		dst[start] = v/10 + '0'
+		return 2
+	}
+
+	dst[start+2] = v%10 + '0'
+	dst[start+1] = (v/10)%10 + '0'
+	dst[start] = v/100 + '0'
+	return 3
+}

iputil/util_test.go

@@ -0,0 +1,17 @@
+package iputil
+
+import (
+	"net"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestVpnIp_String(t *testing.T) {
+	assert.Equal(t, "255.255.255.255", Ip2VpnIp(net.ParseIP("255.255.255.255")).String())
+	assert.Equal(t, "1.255.255.255", Ip2VpnIp(net.ParseIP("1.255.255.255")).String())
+	assert.Equal(t, "1.1.255.255", Ip2VpnIp(net.ParseIP("1.1.255.255")).String())
+	assert.Equal(t, "1.1.1.255", Ip2VpnIp(net.ParseIP("1.1.1.255")).String())
+	assert.Equal(t, "1.1.1.1", Ip2VpnIp(net.ParseIP("1.1.1.1")).String())
+	assert.Equal(t, "0.0.0.0", Ip2VpnIp(net.ParseIP("0.0.0.0")).String())
+}