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net.go
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net.go
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// Copyright (c) Microsoft Corporation.
// Licensed under the Apache v2.0 license.
package net
import (
"fmt"
"math/big"
"net"
)
const (
LOOPBACK_ADDRESS = "127.0.0.1"
)
func GetIPAddress() (string, error) {
conn, err := net.Dial("udp", "8.8.8.8:80")
if err != nil {
return "", err
}
defer conn.Close()
return conn.LocalAddr().(*net.UDPAddr).IP.String(), nil
}
func StringToNetIPAddress(ipString string) net.IP {
return net.ParseIP(ipString)
}
func ParseMAC(macString string) (net.HardwareAddr, error) {
var macInt big.Int
// Hyper-V uses non-standard MAC address formats (with no colons and no dashes)
_, success := macInt.SetString(macString, 16)
if success {
macBytes := macInt.Bytes()
for i := len(macBytes); i < 6; i++ {
macBytes = append([]byte{0}, macBytes...)
}
hardwareAddr := net.HardwareAddr(macBytes)
return hardwareAddr, nil
}
hardwareAddr, err := net.ParseMAC(macString)
if err != nil {
return nil, err
}
return hardwareAddr, nil
}
func Or(ip, ip1 net.IP) net.IP {
b := make([]byte, len(ip))
for i := 0; i < len(ip); i++ {
b[i] = ip[i] | ip1[i]
}
return b
}
func Not(ip net.IP) net.IP {
b := make([]byte, len(ip))
for i := 0; i < len(ip); i++ {
b[i] = ^ip[i]
}
return b
}
func Increment(ip net.IP) net.IP {
newip := make([]byte, len(ip))
copy(newip, ip)
for i := len(ip) - 1; i >= 0; i-- {
newip[i] = ip[i] + 1
if newip[i] > 0 {
break
}
}
return newip
}
func Decrement(ip net.IP) net.IP {
newip := make([]byte, len(ip))
copy(newip, ip)
for i := len(ip) - 1; i >= 0; i-- {
newip[i] = ip[i] - 1
if newip[i] < 255 {
break
}
}
return newip
}
func GetCIDR(startip, endip net.IP) (*net.IPNet, error) {
if len(startip) != len(endip) {
return nil, fmt.Errorf("Can not compute CIDR for %s and %s. Start and end range have different sizes (%d %d)", startip, endip, len(startip), len(endip))
}
var prefixlen uint = 0
exit := false
for i := 0; i < len(startip) && !exit; i++ {
for j := 0; j < 8 && !exit; j++ {
mask := byte(1 << (7 - j))
if (startip[i] & mask) == (endip[i] & mask) {
prefixlen++
} else {
exit = true
}
}
}
mask := net.CIDRMask(int(prefixlen), len(startip)*8)
//Find the start of the CIDR we need to allocate
rangeStartIP := startip.Mask(mask)
//fmt.Printf("the range to allocate for %s - %s is: %s\\%d\n", sip, eip, rangeStartIP, prefixlen)
return &net.IPNet{
IP: rangeStartIP,
Mask: mask,
}, nil
}
func GetBroadcastAddress(cidr net.IPNet) net.IP {
broadcastip := Or(cidr.IP, Not(net.IP(cidr.Mask)))
if len(broadcastip) == net.IPv6len {
return broadcastip
}
// IPv4 (10.0.0.255) addresses are typically represented as IPv4 mapped IPv6 address (0:0:0:0:0:FFFF:10.0.0.255) in the net.IP structure.
// However, the net.IPNet structure stores the IPv4 address in a net.IPv4Len array.
// So, we convert the ipv4 address to a ipv4 mapped ipv6 address to be consistent with net.ParseIP()
// By converting to a ipv4 mappend ipv6 address callers can use this function in a more natural manner like
// GetBroadcastAddress(cidr) == net.ParseIP(10.0.0.255)
broadcastip = net.ParseIP(broadcastip.String())
return broadcastip
}
func PrefixesOverlap(cidr1 net.IPNet, cidr2 net.IPNet) bool {
if cidr1.Contains(cidr2.IP) || cidr2.Contains(cidr1.IP) {
return true
}
return false
}
func GetNetworkInterface() (string, error) {
// get primary public IP address
primaryPublicIP, err := GetIPAddress()
if err != nil {
return "", err
}
networkInterfaces, err := net.Interfaces()
if err != nil {
return "", err
}
for _, networkInterface := range networkInterfaces {
// return this interface iff it contains the
// primary public IP address
// skip down interface
if networkInterface.Flags&net.FlagUp == 0 {
continue
}
// skip loopback
if networkInterface.Flags&net.FlagLoopback != 0 {
continue
}
// list of unicast interface addresses for specific interface
addresses, err := networkInterface.Addrs()
if err != nil {
return "", err
}
// network end point address
for _, address := range addresses {
var ip net.IP
switch typedAddress := address.(type) {
case *net.IPNet:
ip = typedAddress.IP
case *net.IPAddr:
ip = typedAddress.IP
}
// skip loopback or wrong type
if ip == nil || ip.IsLoopback() {
continue
}
if ip.String() == primaryPublicIP {
// return this interface
return networkInterface.Name, nil
}
}
}
return "", fmt.Errorf("No network interfaces found")
}
func lessThan(left, right net.IP) bool {
var l, r big.Int
l.SetBytes(left)
r.SetBytes(right)
if l.Cmp(&r) == -1 {
return true
}
return false
}
func greaterThan(left, right net.IP) bool {
var l, r big.Int
l.SetBytes(left)
r.SetBytes(right)
if l.Cmp(&r) == 1 {
return true
}
return false
}
func RangesOverlap(range1start, range1end, range2start, range2end net.IP) bool {
if lessThan(range1start, range2start) && lessThan(range2start, range1end) {
return true
}
if lessThan(range2start, range1start) && lessThan(range1start, range2end) {
return true
}
if range1start.Equal(range2start) || range1end.Equal(range2end) {
return true
}
if range1end.Equal(range2start) || range1start.Equal(range2end) {
return true
}
return false
}
func IsRangeInCIDR(start, end net.IP, cidr *net.IPNet) bool {
if cidr.Contains(start) && cidr.Contains(end) {
return true
}
return false
}
func RangeContains(start, end, ip net.IP) bool {
if x := start.To4(); x != nil {
start = x
}
if x := end.To4(); x != nil {
end = x
}
if x := ip.To4(); x != nil {
ip = x
}
if len(ip) != len(start) {
return false
}
if len(ip) != len(end) {
return false
}
if ip.Equal(start) || ip.Equal(end) {
return true
}
if greaterThan(ip, start) && lessThan(ip, end) {
return true
}
return false
}
//TODO: Create an IPRange class.