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: [1.18.x, 1.19.x]
+        go-version: [1.23.x, 1.24.x]
         os: [ubuntu-latest]
     runs-on: ${{matrix.os}}
     steps:

README.md

@@ -33,10 +33,10 @@ go get github.com/sony/sonyflake
 Usage
 -----
 
-The function NewSonyflake creates a new Sonyflake instance.
+The function New creates a new Sonyflake instance.
 
 ```go
-func NewSonyflake(st Settings) *Sonyflake
+func New(st Settings) (*Sonyflake, error)
 ```
 
 You can configure Sonyflake by the struct Settings:
@@ -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.

mock/sonyflake_mock.go

@@ -0,0 +1,35 @@
+// Package mock offers implementations of interfaces defined in types.go
+// This allows complete control over input / output for any given method that consumes
+// a given type
+package mock
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/sony/sonyflake/types"
+)
+
+// NewSuccessfulInterfaceAddrs returns a single private IP address
+func NewSuccessfulInterfaceAddrs() types.InterfaceAddrs {
+	ifat := make([]net.Addr, 0, 1)
+	ifat = append(ifat, &net.IPNet{IP: []byte{192, 168, 0, 1}, Mask: []byte{255, 0, 0, 0}})
+
+	return func() ([]net.Addr, error) {
+		return ifat, nil
+	}
+}
+
+// NewFailingInterfaceAddrs returns an error
+func NewFailingInterfaceAddrs() types.InterfaceAddrs {
+	return func() ([]net.Addr, error) {
+		return nil, fmt.Errorf("test error")
+	}
+}
+
+// NewFailingInterfaceAddrs returns an empty slice of addresses
+func NewNilInterfaceAddrs() types.InterfaceAddrs {
+	return func() ([]net.Addr, error) {
+		return []net.Addr{}, nil
+	}
+}

sonyflake.go

@@ -12,6 +12,8 @@ import (
 	"net"
 	"sync"
 	"time"
+
+	"github.com/sony/sonyflake/types"
 )
 
 // These constants are the bit lengths of Sonyflake ID parts.
@@ -50,19 +52,29 @@ type Sonyflake struct {
 	machineID   uint16
 }
 
-// NewSonyflake returns a new Sonyflake configured with the given Settings.
-// NewSonyflake returns nil in the following cases:
+var (
+	ErrStartTimeAhead   = errors.New("start time is ahead of now")
+	ErrNoPrivateAddress = errors.New("no private ip address")
+	ErrOverTimeLimit    = errors.New("over the time limit")
+	ErrInvalidMachineID = errors.New("invalid machine id")
+)
+
+var defaultInterfaceAddrs = net.InterfaceAddrs
+
+// New returns a new Sonyflake configured with the given Settings.
+// New returns an error in the following cases:
 // - Settings.StartTime is ahead of the current time.
 // - Settings.MachineID returns an error.
 // - Settings.CheckMachineID returns false.
-func NewSonyflake(st Settings) *Sonyflake {
+func New(st Settings) (*Sonyflake, error) {
+	if st.StartTime.After(time.Now()) {
+		return nil, ErrStartTimeAhead
+	}
+
 	sf := new(Sonyflake)
 	sf.mutex = new(sync.Mutex)
 	sf.sequence = uint16(1<<BitLenSequence - 1)
 
-	if st.StartTime.After(time.Now()) {
-		return nil
-	}
 	if st.StartTime.IsZero() {
 		sf.startTime = toSonyflakeTime(time.Date(2014, 9, 1, 0, 0, 0, 0, time.UTC))
 	} else {
@@ -71,14 +83,28 @@ func NewSonyflake(st Settings) *Sonyflake {
 
 	var err error
 	if st.MachineID == nil {
-		sf.machineID, err = lower16BitPrivateIP()
+		sf.machineID, err = lower16BitPrivateIP(defaultInterfaceAddrs)
 	} else {
 		sf.machineID, err = st.MachineID()
 	}
-	if err != nil || (st.CheckMachineID != nil && !st.CheckMachineID(sf.machineID)) {
-		return nil
+	if err != nil {
+		return nil, err
 	}
 
+	if st.CheckMachineID != nil && !st.CheckMachineID(sf.machineID) {
+		return nil, ErrInvalidMachineID
+	}
+
+	return sf, nil
+}
+
+// NewSonyflake returns a new Sonyflake configured with the given Settings.
+// NewSonyflake returns nil in the following cases:
+// - Settings.StartTime is ahead of the current time.
+// - Settings.MachineID returns an error.
+// - Settings.CheckMachineID returns false.
+func NewSonyflake(st Settings) *Sonyflake {
+	sf, _ := New(st)
 	return sf
 }
 
@@ -123,7 +149,7 @@ func sleepTime(overtime int64) time.Duration {
 
 func (sf *Sonyflake) toID() (uint64, error) {
 	if sf.elapsedTime >= 1<<BitLenTime {
-		return 0, errors.New("over the time limit")
+		return 0, ErrOverTimeLimit
 	}
 
 	return uint64(sf.elapsedTime)<<(BitLenSequence+BitLenMachineID) |
@@ -131,8 +157,8 @@ func (sf *Sonyflake) toID() (uint64, error) {
 		uint64(sf.machineID), nil
 }
 
-func privateIPv4() (net.IP, error) {
-	as, err := net.InterfaceAddrs()
+func privateIPv4(interfaceAddrs types.InterfaceAddrs) (net.IP, error) {
+	as, err := interfaceAddrs()
 	if err != nil {
 		return nil, err
 	}
@@ -148,16 +174,17 @@ func privateIPv4() (net.IP, error) {
 			return ip, nil
 		}
 	}
-	return nil, errors.New("no private ip address")
+	return nil, ErrNoPrivateAddress
 }
 
 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() (uint16, error) {
-	ip, err := privateIPv4()
+func lower16BitPrivateIP(interfaceAddrs types.InterfaceAddrs) (uint16, error) {
+	ip, err := privateIPv4(interfaceAddrs)
 	if err != nil {
 		return 0, err
 	}

sonyflake_test.go

@@ -1,10 +1,15 @@
 package sonyflake
 
 import (
+	"errors"
 	"fmt"
+	"net"
 	"runtime"
 	"testing"
 	"time"
+
+	"github.com/sony/sonyflake/mock"
+	"github.com/sony/sonyflake/types"
 )
 
 var sf *Sonyflake
@@ -23,7 +28,7 @@ func init() {
 
 	startTime = toSonyflakeTime(st.StartTime)
 
-	ip, _ := lower16BitPrivateIP()
+	ip, _ := lower16BitPrivateIP(defaultInterfaceAddrs)
 	machineID = uint64(ip)
 }
 
@@ -35,6 +40,60 @@ func nextID(t *testing.T) uint64 {
 	return id
 }
 
+func TestNew(t *testing.T) {
+	genError := fmt.Errorf("an error occurred while generating ID")
+
+	tests := []struct {
+		name     string
+		settings Settings
+		err      error
+	}{
+		{
+			name: "failure: time ahead",
+			settings: Settings{
+				StartTime: time.Now().Add(time.Minute),
+			},
+			err: ErrStartTimeAhead,
+		},
+		{
+			name: "failure: machine ID",
+			settings: Settings{
+				MachineID: func() (uint16, error) {
+					return 0, genError
+				},
+			},
+			err: genError,
+		},
+		{
+			name: "failure: invalid machine ID",
+			settings: Settings{
+				CheckMachineID: func(uint16) bool {
+					return false
+				},
+			},
+			err: ErrInvalidMachineID,
+		},
+		{
+			name:     "success",
+			settings: Settings{},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			sonyflake, err := New(test.settings)
+
+			if !errors.Is(err, test.err) {
+				t.Fatalf("unexpected value, want %#v, got %#v", test.err, err)
+			}
+
+			if sonyflake == nil && err == nil {
+				t.Fatal("unexpected value, sonyflake should not be nil")
+			}
+		})
+	}
+}
+
 func TestSonyflakeOnce(t *testing.T) {
 	sleepTime := time.Duration(50 * sonyflakeTimeUnit)
 	time.Sleep(sleepTime)
@@ -76,9 +135,12 @@ func TestSonyflakeFor10Sec(t *testing.T) {
 		parts := Decompose(id)
 		numID++
 
-		if id <= lastID {
+		if id == lastID {
 			t.Fatal("duplicated id")
 		}
+		if id < lastID {
+			t.Fatal("must increase with time")
+		}
 		lastID = id
 
 		current = currentTime()
@@ -142,30 +204,6 @@ func TestSonyflakeInParallel(t *testing.T) {
 	fmt.Println("number of id:", len(set))
 }
 
-func TestNilSonyflake(t *testing.T) {
-	var startInFuture Settings
-	startInFuture.StartTime = time.Now().Add(time.Duration(1) * time.Minute)
-	if NewSonyflake(startInFuture) != nil {
-		t.Errorf("sonyflake starting in the future")
-	}
-
-	var noMachineID Settings
-	noMachineID.MachineID = func() (uint16, error) {
-		return 0, fmt.Errorf("no machine id")
-	}
-	if NewSonyflake(noMachineID) != nil {
-		t.Errorf("sonyflake with no machine id")
-	}
-
-	var invalidMachineID Settings
-	invalidMachineID.CheckMachineID = func(uint16) bool {
-		return false
-	}
-	if NewSonyflake(invalidMachineID) != nil {
-		t.Errorf("sonyflake with invalid machine id")
-	}
-}
-
 func pseudoSleep(period time.Duration) {
 	sf.startTime -= int64(period) / sonyflakeTimeUnit
 }
@@ -182,6 +220,93 @@ func TestNextIDError(t *testing.T) {
 	}
 }
 
+func TestPrivateIPv4(t *testing.T) {
+	testCases := []struct {
+		description    string
+		expected       net.IP
+		interfaceAddrs types.InterfaceAddrs
+		error          string
+	}{
+		{
+			description:    "InterfaceAddrs returns an error",
+			expected:       nil,
+			interfaceAddrs: mock.NewFailingInterfaceAddrs(),
+			error:          "test error",
+		},
+		{
+			description:    "InterfaceAddrs returns an empty or nil list",
+			expected:       nil,
+			interfaceAddrs: mock.NewNilInterfaceAddrs(),
+			error:          "no private ip address",
+		},
+		{
+			description:    "InterfaceAddrs returns one or more IPs",
+			expected:       net.IP{192, 168, 0, 1},
+			interfaceAddrs: mock.NewSuccessfulInterfaceAddrs(),
+			error:          "",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.description, func(t *testing.T) {
+			actual, err := privateIPv4(tc.interfaceAddrs)
+
+			if (err != nil) && (tc.error == "") {
+				t.Errorf("expected no error, but got: %s", err)
+				return
+			} else if (err != nil) && (tc.error != "") {
+				return
+			}
+
+			if net.IP.Equal(actual, tc.expected) {
+				return
+			} else {
+				t.Errorf("error: expected: %s, but got: %s", tc.expected, actual)
+			}
+		})
+	}
+}
+
+func TestLower16BitPrivateIP(t *testing.T) {
+	testCases := []struct {
+		description    string
+		expected       uint16
+		interfaceAddrs types.InterfaceAddrs
+		error          string
+	}{
+		{
+			description:    "InterfaceAddrs returns an empty or nil list",
+			expected:       0,
+			interfaceAddrs: mock.NewNilInterfaceAddrs(),
+			error:          "no private ip address",
+		},
+		{
+			description:    "InterfaceAddrs returns one or more IPs",
+			expected:       1,
+			interfaceAddrs: mock.NewSuccessfulInterfaceAddrs(),
+			error:          "",
+		},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.description, func(t *testing.T) {
+			actual, err := lower16BitPrivateIP(tc.interfaceAddrs)
+
+			if (err != nil) && (tc.error == "") {
+				t.Errorf("expected no error, but got: %s", err)
+				return
+			} else if (err != nil) && (tc.error != "") {
+				return
+			}
+
+			if actual == tc.expected {
+				return
+			} else {
+				t.Errorf("error: expected: %v, but got: %v", tc.expected, actual)
+			}
+		})
+	}
+}
+
 func TestSonyflakeTimeUnit(t *testing.T) {
 	if time.Duration(sonyflakeTimeUnit) != 10*time.Millisecond {
 		t.Errorf("unexpected time unit")

types/types.go

@@ -0,0 +1,8 @@
+// Package Types defines type signatures used throughout SonyFlake. This allows for
+// fine-tuned control over imports, and the ability to mock out imports as well
+package types
+
+import "net"
+
+// InterfaceAddrs defines the interface used for retrieving network addresses
+type InterfaceAddrs func() ([]net.Addr, error)