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goiste · Aug 11, 2022 · 1f8c08a · 1f8c08a
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diff --git a/.gitignore b/.gitignore
@@ -0,0 +1 @@
+.idea
diff --git a/README.md b/README.md
@@ -0,0 +1,3 @@
+# CIDR Parse
+
+Split CIDR to the range of IP addresses.
diff --git a/cidr_parse.go b/cidr_parse.go
@@ -0,0 +1,116 @@
+package cidr_parse
+
+import (
+	"fmt"
+	"net"
+	"strconv"
+	"strings"
+)
+
+const (
+	maskFull   = 0xffffffff
+	maskFirst  = 0xff000000
+	maskSecond = 0x00ff0000
+	maskThird  = 0x0000ff00
+	maskLast   = 0x000000ff
+
+	maskShiftFirst  = 24
+	maskShiftSecond = 16
+	maskShiftThird  = 8
+)
+
+// CIDRParse converts CIDR to the range of IPs (v4 only in this version)
+type CIDRParse struct {
+	firstIP uint32
+	lastIP  uint32
+}
+
+func NewCIDRParse(cidr string, includeFirstZero bool) (*CIDRParse, error) {
+	_, ipNet, err := net.ParseCIDR(cidr)
+	if err != nil {
+		return nil, fmt.Errorf("error parsing CIDR %q: %w", cidr, err)
+	}
+
+	bits, size := ipNet.Mask.Size()
+	if size != 32 {
+		return nil, fmt.Errorf("unsupported mask size: %d", size)
+	}
+
+	zeroIP := ipToUint32(ipNet.IP.String())
+
+	firstIP := zeroIP
+	if !includeFirstZero && zeroIP&maskLast == 0 {
+		firstIP++
+	}
+
+	lastIP := zeroIP | (maskFull >> bits)
+
+	return &CIDRParse{
+		firstIP: firstIP,
+		lastIP:  lastIP,
+	}, nil
+}
+
+// FirstIP is a first IP address of the range
+func (r CIDRParse) FirstIP() string {
+	return uint32ToIP(r.firstIP)
+}
+
+// LastIP is a last IP address of the range
+func (r CIDRParse) LastIP() string {
+	return uint32ToIP(r.lastIP)
+}
+
+// Len is a length of the range
+func (r CIDRParse) Len() int {
+	return int(r.lastIP - r.firstIP + 1)
+}
+
+// List returns all IPs as a string slice
+func (r CIDRParse) List() []string {
+	list := make([]string, 0, r.Len())
+	next := r.NextIPFunc()
+	ip, ok := next()
+	for ok {
+		list = append(list, ip)
+		ip, ok = next()
+	}
+	return list
+}
+
+// NextIPFunc returns a generator function to iterate IPs one by one
+func (r CIDRParse) NextIPFunc() func() (string, bool) {
+	offset := uint32(0)
+	return func() (string, bool) {
+		ip := r.firstIP + offset
+		var ok bool
+		if ip > r.lastIP {
+			ip = r.lastIP
+		} else {
+			offset++
+			ok = true
+		}
+		return uint32ToIP(ip), ok
+	}
+}
+
+// converts IP address string to uint32 number
+func ipToUint32(ip string) uint32 {
+	octets := make([]uint64, 4)
+	for i, part := range strings.Split(ip, ".") {
+		octets[i], _ = strconv.ParseUint(part, 10, 32)
+	}
+
+	return uint32(octets[0]<<maskShiftFirst | octets[1]<<maskShiftSecond | octets[2]<<maskShiftThird | octets[3])
+}
+
+// converts uint32 number to IP string
+func uint32ToIP(ip uint32) string {
+	return fmt.Sprintf(
+		"%d.%d.%d.%d",
+		ip&maskFirst>>maskShiftFirst,
+		ip&maskSecond>>maskShiftSecond,
+		ip&maskThird>>maskShiftThird,
+		ip&maskLast,
+	)
+}
diff --git a/cidr_parse_test.go b/cidr_parse_test.go
@@ -0,0 +1,191 @@
+package cidr_parse
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestIpToUint32(t *testing.T) {
+	tests := []struct {
+		Name   string
+		IP     string
+		Result uint32
+	}{
+		{Name: "10.0.0.0", IP: "10.0.0.0", Result: 0xa000000},
+		{Name: "127.0.0.1", IP: "127.0.0.1", Result: 0x7f000001},
+		{Name: "255.255.255.255", IP: "255.255.255.255", Result: maskFull},
+		{Name: "255.0.0.0", IP: "255.0.0.0", Result: maskFirst},
+		{Name: "0.255.0.0", IP: "0.255.0.0", Result: maskSecond},
+		{Name: "0.0.255.0", IP: "0.0.255.0", Result: maskThird},
+		{Name: "0.0.0.255", IP: "0.0.0.255", Result: maskLast},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			res := ipToUint32(tt.IP)
+			require.Equal(t, tt.Result, res)
+		})
+	}
+}
+
+func TestCIDRRange_New(t *testing.T) {
+	tests := []struct {
+		Name      string
+		CIDR      string
+		NeedError bool
+	}{
+		{Name: "empty_cidr", CIDR: "", NeedError: true},
+		{Name: "invalid_cidr", CIDR: "10.0.0.0/33", NeedError: true},
+		{Name: "invalid_string", CIDR: "test", NeedError: true},
+		{Name: "valid_cidr", CIDR: "10.0.0.0/16", NeedError: false},
+		{Name: "invalid_mask_size", CIDR: "2001:db8:0:160::/64", NeedError: true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			_, err := NewCIDRParse(tt.CIDR, true)
+			toggleError(t, err, tt.NeedError)
+		})
+	}
+}
+
+func TestCIDRRange_FirstIP(t *testing.T) {
+	tests := []struct {
+		Name        string
+		CIDR        string
+		IncludeZero bool
+		FirstIP     string
+	}{
+		{Name: "10.0.0.0/16", CIDR: "10.0.0.0/16", IncludeZero: true, FirstIP: "10.0.0.0"},
+		{Name: "10.0.0.0/16", CIDR: "10.0.0.0/16", FirstIP: "10.0.0.1"},
+		{Name: "10.0.0.0/32", CIDR: "10.0.0.0/32", IncludeZero: true, FirstIP: "10.0.0.0"},
+		{Name: "10.0.0.0/32", CIDR: "10.0.0.0/32", FirstIP: "10.0.0.1"},
+		{Name: "10.0.0.127/32", CIDR: "10.0.0.127/32", FirstIP: "10.0.0.127"},
+		{Name: "10.0.255.128/16", CIDR: "10.0.255.128/16", IncludeZero: true, FirstIP: "10.0.0.0"},
+		{Name: "10.0.255.128/16", CIDR: "10.0.255.128/16", FirstIP: "10.0.0.1"},
+		{Name: "10.0.255.128/24", CIDR: "10.0.255.128/24", IncludeZero: true, FirstIP: "10.0.255.0"},
+		{Name: "10.0.255.128/24", CIDR: "10.0.255.128/24", FirstIP: "10.0.255.1"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			r, err := NewCIDRParse(tt.CIDR, tt.IncludeZero)
+			require.NoError(t, err)
+			require.Equal(t, tt.FirstIP, r.FirstIP())
+		})
+	}
+}
+
+func TestCIDRRange_LastIP(t *testing.T) {
+	tests := []struct {
+		Name   string
+		CIDR   string
+		LastIP string
+	}{
+		{Name: "10.0.0.0/32", CIDR: "10.0.0.0/32", LastIP: "10.0.0.0"},
+		{Name: "10.0.0.127/32", CIDR: "10.0.0.127/32", LastIP: "10.0.0.127"},
+		{Name: "10.0.0.0/28", CIDR: "10.0.0.0/25", LastIP: "10.0.0.127"},
+		{Name: "10.0.0.0/24", CIDR: "10.0.0.0/24", LastIP: "10.0.0.255"},
+		{Name: "10.0.0.0/16", CIDR: "10.0.0.0/16", LastIP: "10.0.255.255"},
+		{Name: "10.0.0.0/8", CIDR: "10.0.0.0/8", LastIP: "10.255.255.255"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			r, err := NewCIDRParse(tt.CIDR, true)
+			require.NoError(t, err)
+			require.Equal(t, tt.LastIP, r.LastIP())
+		})
+	}
+}
+
+func TestCIDRRange_Len(t *testing.T) {
+	tests := []struct {
+		Name        string
+		CIDR        string
+		IncludeZero bool
+		Len         int
+	}{
+		{Name: "10.0.0.0/32", CIDR: "10.0.0.0/32", IncludeZero: true, Len: 1},
+		{Name: "10.0.0.0/32", CIDR: "10.0.0.0/32", Len: 0},
+		{Name: "10.0.0.0/24", IncludeZero: true, CIDR: "10.0.0.0/24", Len: 256},
+		{Name: "10.0.0.0/24", CIDR: "10.0.0.0/24", Len: 255},
+		{Name: "10.0.0.0/16", CIDR: "10.0.0.0/16", IncludeZero: true, Len: 65536},
+		{Name: "10.0.0.0/16", CIDR: "10.0.0.0/16", Len: 65535},
+		{Name: "10.0.0.0/8", CIDR: "10.0.0.0/8", IncludeZero: true, Len: 16777216},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			r, err := NewCIDRParse(tt.CIDR, tt.IncludeZero)
+			require.NoError(t, err)
+			require.Equal(t, tt.Len, r.Len())
+		})
+	}
+}
+
+func TestCIDRRange_List(t *testing.T) {
+	tests := []struct {
+		Name      string
+		CIDR      string
+		ListCount int
+	}{
+		{Name: "10.0.0.0/32", CIDR: "10.0.0.0/32", ListCount: 1},
+		{Name: "10.0.0.127/32", CIDR: "10.0.0.127/32", ListCount: 1},
+		{Name: "10.0.0.0/28", CIDR: "10.0.0.0/25", ListCount: 128},
+		{Name: "10.0.0.0/24", CIDR: "10.0.0.0/24", ListCount: 256},
+		{Name: "10.0.0.0/19", CIDR: "10.0.0.0/19", ListCount: 8192},
+		{Name: "10.0.0.0/16", CIDR: "10.0.0.0/16", ListCount: 65536},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			r, err := NewCIDRParse(tt.CIDR, true)
+			require.NoError(t, err)
+			require.Equal(t, tt.ListCount, len(r.List()))
+		})
+	}
+}
+
+func TestCIDRRange_NextIPFunc(t *testing.T) {
+	tests := []struct {
+		Name      string
+		CIDR      string
+		RunsCount int
+		IsOk      bool
+		IP        string
+	}{
+		{Name: "10.0.0.0/32", CIDR: "10.0.0.0/32", RunsCount: 1, IsOk: true, IP: "10.0.0.0"},
+		{Name: "10.0.0.0/32", CIDR: "10.0.0.0/32", RunsCount: 2, IsOk: false, IP: "10.0.0.0"},
+		{Name: "10.0.0.0/24", CIDR: "10.0.0.0/24", RunsCount: 1, IsOk: true, IP: "10.0.0.0"},
+		{Name: "10.0.0.0/24", CIDR: "10.0.0.0/24", RunsCount: 42, IsOk: true, IP: "10.0.0.41"},
+		{Name: "10.0.0.0/24", CIDR: "10.0.0.0/24", RunsCount: 256, IsOk: true, IP: "10.0.0.255"},
+		{Name: "10.0.0.0/24", CIDR: "10.0.0.0/24", RunsCount: 257, IsOk: false, IP: "10.0.0.255"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			r, err := NewCIDRParse(tt.CIDR, true)
+			require.NoError(t, err)
+
+			ip := ""
+			ok := false
+
+			next := r.NextIPFunc()
+			for i := 0; i < tt.RunsCount; i++ {
+				ip, ok = next()
+			}
+			require.Equal(t, tt.IsOk, ok)
+			require.Equal(t, tt.IP, ip)
+		})
+	}
+}
+
+func toggleError(t *testing.T, err error, needError bool) {
+	if needError {
+		require.Error(t, err)
+	} else {
+		require.NoError(t, err)
+	}
+}
diff --git a/go.mod b/go.mod
@@ -0,0 +1,11 @@
+module github.com/goiste/cidr_parse
+
+go 1.18
+
+require github.com/stretchr/testify v1.8.0
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
diff --git a/go.sum b/go.sum
@@ -0,0 +1,15 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,3 @@
		# CIDR Parse

		Split CIDR to the range of IP addresses.