Subnet command #4

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Merged

fremartini merged 8 commits into main from subnet_command

Mar 10, 2025

.github/workflows/release.yml

            
                      Original file line number
                      Diff line number
                      Diff line change
                  
    @@ -9,7 +9,7 @@ env:
  
      REPO_NAME: ${{ github.event.repository.name }}

      OUT_FOLDER: ${{ github.event.repository.name }}

      EXECUTABLE_NAME: ${{ github.event.repository.name }}

      GO_VERSION: '1.23'

      GO_VERSION: '1.24'

    permissions:

      contents: write

    @@ -47,7 +47,7 @@ jobs:
  
            go-version: ${{ env.GO_VERSION }}

        - name: Build ${{ env.OS_GOOS }}/${{ env.OS_GOARCH }}

          run: GOOS=${{ env.OS_GOOS }} GOARCH=${{ env.OS_GOARCH }} go build -o ${{ env.EXECUTABLE_NAME }}.exe

          run: GOOS=${{ env.OS_GOOS }} GOARCH=${{ env.OS_GOARCH }} go build -o ${{ env.EXECUTABLE_NAME }}.exe -ldflags "-X main.version=${{ env.VERSION }}"

          shell: bash

        - name: Create archive

.github/workflows/test.yml

-Original file line number
+Diff line change
@@ -0,0 +1,25 @@
+    name: Test
+    on:
+      pull_request:
+        branches: [ "main" ]
+    env:
+      GO_VERSION: '1.24'
+    jobs:
+      build:
+        runs-on: ubuntu-latest
+        steps:
+        - uses: actions/checkout@v3
+        - name: Set up Go
+          uses: actions/setup-go@v4
+          with:
+            go-version: ${{ env.GO_VERSION }}
+        - name: Build
+          run: go build -v ./...
+        - name: Test
+          run: go test -v ./...

go.mod

-Original file line number
+Diff line change
@@ Expand Up / @@ -2,10 +2,4 @@ module cider @@
     go 1.23.2
-    require github.com/urfave/cli/v2 v2.27.5
-    require (
-    	github.com/cpuguy83/go-md2man/v2 v2.0.5 // indirect
-    	github.com/russross/blackfriday/v2 v2.1.0 // indirect
-    	github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 // indirect
-    )
+    require github.com/urfave/cli/v3 v3.0.0-beta1

go.sum

-Original file line number
+Diff line change
@@ Expand Up @@
     github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
     github.com/urfave/cli/v2 v2.27.5 h1:WoHEJLdsXr6dDWoJgMq/CboDmyY/8HMMH1fTECbih+w=
     github.com/urfave/cli/v2 v2.27.5/go.mod h1:3Sevf16NykTbInEnD0yKkjDAeZDS0A6bzhBH5hrMvTQ=
+    github.com/urfave/cli/v3 v3.0.0-beta1 h1:6DTaaUarcM0wX7qj5Hcvs+5Dm3dyUTBbEwIWAjcw9Zg=
+    github.com/urfave/cli/v3 v3.0.0-beta1/go.mod h1:FnIeEMYu+ko8zP1F9Ypr3xkZMIDqW3DR92yUtY39q1Y=
     github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 h1:gEOO8jv9F4OT7lGCjxCBTO/36wtF6j2nSip77qHd4x4=
     github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1/go.mod h1:Ohn+xnUBiLI6FVj/9LpzZWtj1/D6lUovWYBkxHVV3aM=

internal/cidr/cidr_block.go

-Original file line number
+Diff line change
@@ -0,0 +1,172 @@
+    package cidr
+    import (
+    	"cider/internal/list"
+    	"cider/internal/utils"
+    	"fmt"
+    	"math"
+    	"slices"
+    	"strconv"
+    	"strings"
+    )
+    const (
+    	INT_SIZE = 32
+    )
+    type CIDRBlock struct {
+    	Network     string
+    	HostPortion int
+    }
+    func NewBlock(network string) *CIDRBlock {
+    	networkAndHostPortion := strings.Split(network, "/")
+    	networkPortion := networkAndHostPortion[0]
+    	hostPortion := networkAndHostPortion[1]
+    	return &CIDRBlock{
+    		Network:     networkPortion,
+    		HostPortion: must(strconv.Atoi(hostPortion)),
+    	}
+    }
+    func (b *CIDRBlock) Subnet(sizes []int) ([]string, error) {
+    	// sort subnets largest to smallest to prevent fragmentation
+    	slices.Sort(sizes)
+    	next := b
+    	subnets := []string{}
+    	for _, size := range sizes {
+    		subnetBlock := NewBlock(fmt.Sprintf("%s/%v", next.Network, size))
+    		if !b.Contains(subnetBlock.Network) {
+    			return nil, fmt.Errorf("invalid configuration: subnet %s/%v is outside provided network range %s/%v", next.Network, size, b.Network, b.HostPortion)
+    		}
+    		subnets = append(subnets, fmt.Sprintf("%s/%v", subnetBlock.Network, subnetBlock.HostPortion))
+    		next = NewBlock(fmt.Sprintf("%s/%v", subnetBlock.StartAddressOfNextBlock(), size))
+    	}
+    	return subnets, nil
+    }
+    // https://stackoverflow.com/questions/9622967/how-to-see-if-an-ip-address-belongs-inside-of-a-range-of-ips-using-cidr-notation
+    func (b *CIDRBlock) Contains(ip string) bool {
+    	IP_addr := ipToDecimal(ip)
+    	CIDR_addr := ipToDecimal(b.Network)
+    	CIDR_mask := -1 << (INT_SIZE - b.HostPortion)
+    	return (IP_addr & CIDR_mask) == (CIDR_addr & CIDR_mask)
+    }
+    // http://www.aboutmyip.com/AboutMyXApp/IP2Integer.jsp
+    func ipToDecimal(ip string) int {
+    	parts := strings.Split(ip, ".")
+    	base := 10
+    	octet1 := must(strconv.ParseInt(parts[0], base, INT_SIZE))
+    	octet2 := must(strconv.ParseInt(parts[1], base, INT_SIZE))
+    	octet3 := must(strconv.ParseInt(parts[2], base, INT_SIZE))
+    	octet4 := must(strconv.ParseInt(parts[3], base, INT_SIZE))
+    	return int((octet1 * 16777216) + (octet2 * 65536) + (octet3 * 256) + octet4)
+    }
+    func (b *CIDRBlock) NetworkPortionBinary() string {
+    	octets := strings.Split(b.Network, ".")
+    	octets = list.Map(octets, toBin)
+    	return fmt.Sprintf("%s.%s.%s.%s", octets[0], octets[1], octets[2], octets[3])
+    }
+    func toBin(s string) string {
+    	asInt := must(strconv.ParseInt(s, 10, INT_SIZE))
+    	asBinaryString := strconv.FormatInt(asInt, 2)
+    	paddedBynaryString := utils.PadLeft(asBinaryString, '0', 8)
+    	return paddedBynaryString
+    }
+    func (b *CIDRBlock) SubnetMask() string {
+    	ones := strings.Repeat("1", b.HostPortion)
+    	zeroes := strings.Repeat("0", INT_SIZE-b.HostPortion)
+    	mask := ones + zeroes
+    	octets := stringToOctets(mask)
+    	return fmt.Sprintf("%v.%v.%v.%v", octets[0], octets[1], octets[2], octets[3])
+    }
+    func (b *CIDRBlock) AvailableHosts() uint {
+    	numAddresses := math.Pow(2, float64(INT_SIZE)-float64(b.HostPortion))
+    	return uint(numAddresses)
+    }
+    func (b *CIDRBlock) AvailableAzureHosts() string {
+    	// Azure reserves the first four addresses and the last address, for a total of five IP addresses within each subnet
+    	// https://learn.microsoft.com/en-us/azure/virtual-network/virtual-networks-faq#are-there-any-restrictions-on-using-ip-addresses-within-these-subnets
+    	if b.AvailableHosts() >= 5 {
+    		return fmt.Sprintf("%v", b.AvailableHosts()-5)
+    	}
+    	return "N/A"
+    }
+    func (b *CIDRBlock) StartAddressOfNextBlock() string {
+    	octets := strings.Split(b.BroadcastAddress(), ".")
+    	octets = list.Map(octets, toBin)
+    	binStr := strings.Join(octets, "")
+    	next := must(strconv.ParseInt(binStr, 2, INT_SIZE)) + 1
+    	asBinaryString := strconv.FormatInt(next, 2)
+    	asBinaryString = utils.PadLeft(asBinaryString, '0', 32)
+    	octetsInt := stringToOctets(asBinaryString)
+    	return fmt.Sprintf("%v.%v.%v.%v", octetsInt[0], octetsInt[1], octetsInt[2], octetsInt[3])
+    }
+    func (b *CIDRBlock) NetworkAddress() string {
+    	ipBin := strings.ReplaceAll(b.NetworkPortionBinary(), ".", "")[0:b.HostPortion]
+    	broadcast := ipBin + strings.Repeat("0", INT_SIZE-b.HostPortion)
+    	octets := stringToOctets(broadcast)
+    	return fmt.Sprintf("%v.%v.%v.%v", octets[0], octets[1], octets[2], octets[3])
+    }
+    func (b *CIDRBlock) BroadcastAddress() string {
+    	// https://stackoverflow.com/questions/1470792/how-to-calculate-the-ip-range-when-the-ip-address-and-the-netmask-is-given
+    	ipBin := strings.ReplaceAll(b.NetworkPortionBinary(), ".", "")[0:b.HostPortion]
+    	broadcast := ipBin + strings.Repeat("1", INT_SIZE-b.HostPortion)
+    	octets := stringToOctets(broadcast)
+    	return fmt.Sprintf("%v.%v.%v.%v", octets[0], octets[1], octets[2], octets[3])
+    }
+    func stringToOctets(ipString string) []int64 {
+    	octets := make([]int64, 4)
+    	base := 2
+    	octets[0] = must(strconv.ParseInt(ipString[0:8], base, INT_SIZE))
+    	octets[1] = must(strconv.ParseInt(ipString[8:16], base, INT_SIZE))
+    	octets[2] = must(strconv.ParseInt(ipString[16:24], base, INT_SIZE))
+    	octets[3] = must(strconv.ParseInt(ipString[24:32], base, INT_SIZE))
+    	return octets
+    }
+    func must[T any](x T, e error) T {
+    	if e != nil {
+    		panic(e)
+    	}
+    	return x
+    }

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