Fix a missing link (#65)

* Allow IPv4 Link Local addresses (#50)

* Allow IPv4 Link Local addresses

Allow the use of link local addresses

* Update sonyflake.go

* Update sonyflake.go

* Update a comment

---------

Co-authored-by: Flavio Crisciani <f.crisciani@gmail.com>

.github/workflows/test.yml

@@ -4,7 +4,7 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.20.x, 1.21.x]
+        go-version: [1.23.x, 1.24.x]
         os: [ubuntu-latest]
     runs-on: ${{matrix.os}}
     steps:

README.md

@@ -83,8 +83,8 @@ the function AmazonEC2MachineID that returns the lower 16-bit private IP address
 It also works correctly on Docker
 by retrieving [instance metadata](http://docs.aws.amazon.com/en_us/AWSEC2/latest/UserGuide/ec2-instance-metadata.html).
 
-[AWS VPC](http://docs.aws.amazon.com/en_us/AmazonVPC/latest/UserGuide/VPC_Subnets.html)
-is assigned a single CIDR with a netmask between /28 and /16.
+[AWS IPv4 VPC](https://docs.aws.amazon.com/vpc/latest/userguide/vpc-cidr-blocks.html)
+is usually assigned a single CIDR with a netmask between /28 and /16.
 So if each EC2 instance has a unique private IP address in AWS VPC,
 the lower 16 bits of the address is also unique.
 In this common case, you can use AmazonEC2MachineID as Settings.MachineID.

sonyflake.go

@@ -178,8 +178,9 @@ func privateIPv4(interfaceAddrs types.InterfaceAddrs) (net.IP, error) {
 }
 
 func isPrivateIPv4(ip net.IP) bool {
+	// Allow private IP addresses (RFC1918) and link-local addresses (RFC3927)
 	return ip != nil &&
-		(ip[0] == 10 || ip[0] == 172 && (ip[1] >= 16 && ip[1] < 32) || ip[0] == 192 && ip[1] == 168)
+		(ip[0] == 10 || ip[0] == 172 && (ip[1] >= 16 && ip[1] < 32) || ip[0] == 192 && ip[1] == 168 || ip[0] == 169 && ip[1] == 254)
 }
 
 func lower16BitPrivateIP(interfaceAddrs types.InterfaceAddrs) (uint16, error) {

sonyflake_test.go

@@ -1,7 +1,6 @@
 package sonyflake
 
 import (
-	"bytes"
 	"errors"
 	"fmt"
 	"net"
@@ -259,7 +258,7 @@ func TestPrivateIPv4(t *testing.T) {
 				return
 			}
 
-			if bytes.Equal(actual, tc.expected) {
+			if net.IP.Equal(actual, tc.expected) {
 				return
 			} else {
 				t.Errorf("error: expected: %s, but got: %s", tc.expected, actual)