this is cool and all but the tables don't render properly

.gitignore

@@ -1 +1,42 @@
-cmd/subnetter/subnetter
+*.7z
+*.bak
+*.deb
+*.jar
+*.log
+*.rar
+*.run
+*.sig
+*.tar
+*.tar.bz2
+*.tar.gz
+*.tar.xz
+*.tbz
+*.tbz2
+*.tgz
+*.txz
+*.zip
+.*.swp
+.editix
+.idea/
+
+# https://github.com/github/gitignore/blob/master/Go.gitignore
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+/bin/*
+/_examples
+
+# Test binary, built with `go test -c`
+*.test
+# But allow test suite.
+!*test.go
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# Dependency directories (remove the comment below to include it)
+# vendor/

build.sh

@@ -0,0 +1,127 @@
+#!/usr/bin/env bash
+
+set -e
+
+# This is not portable. It has bashisms.
+
+BUILD_TIME="$(date '+%s')"
+BUILD_USER="$(whoami)"
+BUILD_SUDO_USER="${SUDO_USER}"
+BUILD_HOST="$(hostname)"
+
+# Check to make sure git is available.
+if ! command -v git &> /dev/null;
+then
+  echo "Git is not available; automatic version handling unsupported."
+  echo "You must build by calling 'go build' directly in the respective directories."
+  exit 0
+fi
+
+# Check git directory/repository.
+if ! git rev-parse --is-inside-work-tree &>/dev/null;
+then
+  echo "Not running inside a git work tree; automatic version handling unsupported/build script unsupported."
+  echo "You must build by calling 'go build' directly in the respective directories instead."
+  exit 0
+fi
+
+# The repo URI for origin.
+REPO_URI="$(git remote get-url origin)"
+
+# If it has a tag in the path of the current HEAD that matches a version string...
+# I wish git describe supported regex. It does not; only globs. Gross.
+# If there's a bug anywhere, it's here.
+if git describe --tags --abbrev=0 --match "v[0-9]*" HEAD &> /dev/null;
+then
+  # It has a tag we can use.
+  CURRENT_VER="$(git describe --tags --abbrev=0 --match "v[0-9]*" HEAD)"
+  COMMITS_SINCE="$(git rev-list --count ${CURRENT_VER}..HEAD)"
+else
+  # No tag available.
+  CURRENT_VER=""
+  COMMITS_SINCE=""
+fi
+
+# If it's dirty (staged but not committed or unstaged files)...
+if ! git diff-index --quiet HEAD;
+then
+  # It's dirty.
+  IS_DIRTY="1"
+else
+  # It's clean.
+  IS_DIRTY="0"
+fi
+
+# Get the commit hash of the *most recent* commit in the path of current HEAD...
+CURRENT_HASH="$(git rev-parse --verify HEAD)"
+# The same as above, but abbreviated.
+CURRENT_SHORT="$(git rev-parse --verify --short HEAD)"
+
+# Get the module name.
+MODPATH="$(sed -n -re 's@^\s*module\s+(.*)(//.*)?$@\1@p' go.mod)"
+
+# Build the ldflags string.
+LDFLAGS_STR="\
+-X '${MODPATH}/version.repoUri=${REPO_URI}' \
+-X '${MODPATH}/version.sourceControl=git' \
+-X '${MODPATH}/version.version=${CURRENT_VER}' \
+-X '${MODPATH}/version.commitHash=${CURRENT_HASH}' \
+-X '${MODPATH}/version.commitShort=${CURRENT_SHORT}' \
+-X '${MODPATH}/version.numCommitsAfterTag=${COMMITS_SINCE}' \
+-X '${MODPATH}/version.isDirty=${IS_DIRTY}' \
+-X '${MODPATH}/version.buildTime=${BUILD_TIME}' \
+-X '${MODPATH}/version.buildUser=${BUILD_USER}' \
+-X '${MODPATH}/version.buildSudoUser=${BUILD_SUDO_USER}' \
+-X '${MODPATH}/version.buildHost=${BUILD_HOST}'"
+
+
+# And finally build.
+export CGO_ENABLED=0
+
+mkdir -p ./bin/
+
+cmd="subnetter"
+# Linux
+bin="${cmd}"
+echo "Building ./bin/${bin}..."
+go build \
+	-o "./bin/${bin}" \
+	-ldflags \
+		"${LDFLAGS_STR}" \
+  cmd/${cmd}/*.go
+echo " Done."
+
+# Windows
+GOOS="windows"
+bin="subnetter.exe"
+echo "Building ./bin/${bin}..."
+go build \
+	-o "./bin/${bin}" \
+	-ldflags \
+		"${LDFLAGS_STR}" \
+  cmd/${cmd}/*.go
+echo " Done."
+
+# macOS
+GOOS="darwin"
+## x86_64
+bin="subnetter.x86_64.app"
+echo "Building ./bin/${bin}..."
+go build \
+	-o "./bin/${bin}" \
+	-ldflags \
+		"${LDFLAGS_STR}" \
+  cmd/${cmd}/*.go
+echo " Done."
+## ARM64 (m1/m2/... etc.; "Apple Silicon")
+GOARCH="arm64"
+bin="subnetter.m1.app"
+echo "Building ./bin/${bin}..."
+go build \
+	-o "./bin/${bin}" \
+	-ldflags \
+		"${LDFLAGS_STR}" \
+  cmd/${cmd}/*.go
+echo " Done."
+
+echo "Build complete."

cmd/subnetter/_tpl/table.tpl

@@ -0,0 +1,52 @@
+{{- /*gotype: subnetter/cmd/subnetter.tableOpts*/ -}}
+{{- $opts := . -}}
+{{- $numRows := 0 -}}
+{{- if not $opts.NoIpv4 }}
+IPv4:
+	{{- if $opts.Legacy -}}
+	{{- $legacyspec := legacy4 }}
+	{{- $numRows = len $legacyspec.Rows }}
+
+	LEGACY:
+	{{ $legacyspec.Sizer.Hdr "" $opts.Plain }}
+		{{- range $idx, $row := $legacyspec.Rows }}
+			{{- $row.Row $legacyspec.Sizer "\t" $opts.Plain -}}
+			{{- $legacyspec.Sizer.Line "\t" $opts.Plain $idx $numRows }}
+		{{- end }}
+	{{- end }}
+
+	{{- if not $opts.NoV4Mask }}
+		{{- $masks := mask4 }}
+	NETMASKS:
+	{{ $masks.Sizer.Hdr "\t" $opts.Plain }}
+		{{- range $idx, $row := $masks.Rows }}
+			{{- $row.Row $masks.Sizer "\t" $opts.Plain }}
+			{{- $masks.Sizer.Line "\t" $opts.Plain $idx $numRows }}
+		{{- end }}
+	{{- end }}
+
+	CIDR:
+	{{- $pfxs := addrs 4 }}
+	{{- $numRows = len $pfxs.Rows }}
+	{{ $pfxs.Sizer.Hdr "" $opts.Plain }}
+	{{- range $idx, $row := $pfxs.Rows }}
+		{{- $row.Row $pfxs.Sizer "\t" $opts.Plain }}
+		{{- $pfxs.Sizer.Line "\t" $opts.Plain $idx $numRows }}
+	{{- end }}
+
+{{- end }}
+
+{{- if not $opts.NoIpv6 }}
+
+IPv6:
+
+	CIDR:
+	{{- $pfxs := addrs 6 }}
+	{{- $numRows = len $pfxs.Rows }}
+	{{- $pfxs.Sizer.Hdr "\t" $opts.Plain }}
+	{{- range $idx, $row := $pfxs.Rows }}
+		{{- $row.Row $pfxs.Sizer "\t" $opts.Plain }}
+		{{- $pfxs.Sizer.Line "\t" $opts.Plain $idx $numRows }}
+	{{- end }}
+
+{{- end }}

cmd/subnetter/args.go

@@ -1,19 +1,21 @@
 package main
 
 type Args struct {
-	SplitCIDR    SplitCIDRArgs   `command:"split-cidr" alias:"se" description:"Split a network into as many equal parts of a given prefix as possible." validate:"omitempty"`
-	SplitHost    SplitHostArgs   `command:"split-hosts" alias:"sh" description:"Split a network into n total number of hosts into subnet as cleanly/evenly as possible." validate:"omitempty"`
-	SplitSubnets SplitSubnetArgs `command:"split-nets" alias:"sn" description:"Split a network into n number of subnets as cleanly as possible." validate:"omitempty"`
-	VLSM         VLSMArgs        `command:"vlsm" alias:"v" description:"Use VLSM (Variable-Length Subnet Masks) to split a network into differently sized subnets." validate:"omitempty"`
-	Parse        ParseArgs       `command:"parse" alias:"p" alias:"read" alias:"convert" description:"Parse/convert output from a previous subnetter run." validate:"omitempty"`
-	Table        TableArgs       `command:"table" alias:"t" alias:"tab" alias:"tbl" description:"Show prefix summaries (by default both IPv4 and IPv6)." validate:"omitempty"`
+	Version       bool            `short:"v" long:"version" description:"Print the version and exit."`
+	DetailVersion bool            `short:"V" long:"detail" description:"Print detailed version info and exit."`
+	SplitCIDR     SplitCIDRArgs   `command:"split-cidr" alias:"se" description:"Split a network into as many equal subnets of prefix size N as possible." validate:"omitempty"`
+	SplitHost     SplitHostArgs   `command:"split-hosts" alias:"sh" description:"Split a network into N total number of hosts *per subnet* as cleanly/evenly as possible. (VERY easy to run out of memory for IPv6 prefixes; be sure to specify very small network!)" validate:"omitempty"`
+	SplitSubnets  SplitSubnetArgs `command:"split-nets" alias:"sn" description:"Split a network into N number of subnets as cleanly as possible." validate:"omitempty"`
+	VLSM          VLSMArgs        `command:"vlsm" alias:"v" description:"Use VLSM (Variable-Length Subnet Masks) to split a network into differently sized subnets." validate:"omitempty"`
+	Parse         ParseArgs       `command:"parse" alias:"p" alias:"read" alias:"convert" description:"Parse/convert output from a previous subnetter run." validate:"omitempty"`
+	Table         TableArgs       `command:"table" alias:"t" alias:"tab" alias:"tbl" description:"Show prefix summaries (by default both IPv4 and IPv6)." validate:"omitempty"`
 }
 
 type outputOpts struct {
 	SuppressRemaining bool   `short:"r" long:"no-remaining" description:"Don't show leftover/unallocated/remaining space.'"`
-	Verbose           []bool `short:"v" long:"verbose" description:"Show verbose information. May be specified multiple times to increase verbosity (up to 3 levels)."`
+	Verbose           []bool `short:"v" long:"verbose" description:"Show verbose information if -f/--format=pretty. May be specified multiple times to increase verbosity (up to 3 levels)."`
 	Seperator         string `short:"S" long:"seperator" default:"\n" description:"Separator between addresses; only used for -f/--format=pretty with no verbosity."`
-	Fmt               string `short:"f" long:"format" choice:"json" choice:"pretty" choice:"yml" choice:"xml" default:"pretty" description:"Output format. DO NOT parse 'pretty' as its output is not guaranteed between versions."`
+	Fmt               string `short:"f" long:"format" choice:"json" choice:"pretty" choice:"yml" choice:"xml" default:"pretty" description:"Output format. 'pretty' is not intended to be parseable, either by subnetter or by external tooling."`
 }
 
 type common struct {
@@ -36,21 +38,21 @@ type SplitCIDRArgs struct {
 }
 
 type SplitHostArgs struct {
-	Hosts uint `short:"n" long:"num-hosts" required:"true" description:"Number of hosts (usable addresses) per subnet." validate:"required"`
+	Strict bool `short:"t" long:"strict" description:"If specified, an error will occur if the number of hosts/assignable addresses in a subnet is not exactly -n/--num-hosts."`
+	Hosts  uint `short:"n" long:"num-hosts" required:"true" description:"Number of hosts (usable addresses) per subnet." validate:"required"`
 	common
 }
 
 type SplitSubnetArgs struct {
+	Strict  bool `short:"t" long:"strict" description:"If specified, an error will occur if the number of possible equally-sized subnets is not exactly -n/--num-nets."`
 	NumNets uint `short:"n" long:"num-nets" required:"true" description:"Number of networks." validate:"required"`
 	common
 }
 
 type TableArgs struct {
-	NoIpv6  bool    `short:"4" long:"ipv4" description:"Show IPv4 table."`
-	NoIpv4  bool    `short:"6" long:"ipv6" description:"Show IPv6 table."`
-	Verbose []bool  `short:"v" long:"verbose" description:"Show verbose information. May be specified multiple times to increase verbosity (up to 3 levels)."`
-	Fmt     string  `short:"f" long:"format" choice:"csv" choice:"json" choice:"pretty" choice:"tsv" choice:"yml" choice:"xml" default:"pretty" description:"Output format."`
-	Net     *string `short:"n" long:"network" description:"If specified, provide information explicitly about this network. Ignores -4/--ipv4 and -6/--ipv6." validate:"omitempty,cidr"`
+	tableOpts
+	Verbose []bool  `short:"v" long:"verbose" description:"Show verbose information (if -n/--network is specified). May be specified multiple times to increase verbosity (up to 2 levels)."`
+	Net     *string `short:"n" long:"network" description:"If specified, print detailed information explicitly about this network instead of reference. Ignores all other options except -v/--verbose." validate:"omitempty,cidr"`
 }
 
 type VLSMArgs struct {

cmd/subnetter/consts.go

@@ -1,18 +1,103 @@
 package main
 
 import (
-	"github.com/go-playground/validator/v10"
+	`embed`
 	"strings"
+	`text/template`
+
+	"github.com/go-playground/validator/v10"
 )
 
 var (
-	args     *Args               = new(Args)
-	validate *validator.Validate = validator.New(validator.WithRequiredStructEnabled())
+	args     = new(Args)
+	validate = validator.New(validator.WithRequiredStructEnabled())
+)
+
+const (
+	/*
+		fixedPad is a fixed "surrounding" pad always present (as minimum), even for values max len on columns.
+		*Must* be positive even, as <fixed left pad> and <fixed right pad> == fixedPad/2.
+	*/
+	fixedPad int = 2
+	/*
+		padChars is what fills the pads in table cells.
+		At the *LEAST*, a cell will be "<fixedPad/2 * padChars><str><fixedPad/2 * padChars>"
+	*/
+	padChars string = " "
 )
 
 var (
-	sectSepCnt int    = 48
-	sectSep1   string = strings.Repeat("=", sectSepCnt)
-	sectSep2   string = strings.Repeat("-", sectSepCnt)
-	sectSep3   string = strings.Repeat(".", sectSepCnt)
+	//go:embed "_tpl"
+	tplDir embed.FS
+	tblTpl *template.Template = template.Must(template.New("").Funcs(
+		template.FuncMap{
+			"legacy4": tplClass4Iter,
+			"addrs":   tplAddrIter,
+			"mask4":   tplMaskIter4,
+		},
+	).ParseFS(tplDir, "_tpl/*.tpl"))
+)
+
+var (
+	// Primarily output formatting stuff in this block.
+	sectSepCnt = 48
+	sectSep1   = strings.Repeat("=", sectSepCnt)
+	sectSep2   = strings.Repeat("-", sectSepCnt)
+	sectSep3   = strings.Repeat(".", sectSepCnt)
+	// tblFmts contains a lookup of map[<is plain>]*tableFormatter.
+	tblFmts map[bool]*tableFormatter = map[bool]*tableFormatter{
+		// Plaintext/ASCII-only
+		true: &tableFormatter{
+			TopLeftHdr:      "*", // Or _
+			TopFillHdr:      "*", // ""
+			TopColSepHdr:    "*", // ""
+			TopRightHdr:     "*", // ""
+			ColSepHdr:       "|",
+			BottomLeftHdr:   "*", // Or +
+			BottomFillHdr:   "*", // Or -
+			BottomColSepHdr: "*", // Or +
+			BottomRightHdr:  "*", // ""
+			Left:            "|",
+			Fill:            "-",
+			LineColSep:      "|",
+			LineLeft:        "|",
+			LineRight:       "|",
+			ColSep:          "|",
+			Right:           "|",
+			LastLeft:        "+",
+			LastFill:        "-",
+			LastSep:         "-",
+			LastRight:       "+",
+			SuppressLineSep: true,
+			NoUpperTitle:    false,
+			NoBoldTitle:     true,
+		},
+		// Unicode/UTF-8
+		// https://en.wikipedia.org/wiki/Box-drawing_characters
+		false: &tableFormatter{
+			TopLeftHdr:      "┏",
+			TopFillHdr:      "━",
+			TopColSepHdr:    "┳",
+			TopRightHdr:     "┓",
+			ColSepHdr:       "┃",
+			BottomLeftHdr:   "┣",
+			BottomFillHdr:   "━",
+			BottomColSepHdr: "╇",
+			BottomRightHdr:  "┫",
+			Left:            "┃",
+			Fill:            "─",
+			LineColSep:      "┼",
+			LineLeft:        "┠",
+			LineRight:       "┨",
+			ColSep:          "│",
+			Right:           "┃",
+			LastLeft:        "┗",
+			LastFill:        "━",
+			LastSep:         "┷",
+			LastRight:       "┛",
+			SuppressLineSep: false,
+			NoUpperTitle:    true,
+			NoBoldTitle:     false,
+		},
+	}
 )

cmd/subnetter/errs.go

@@ -0,0 +1,9 @@
+package main
+
+import (
+	`errors`
+)
+
+var (
+	errBadNet error = errors.New("bad inet/addr family/version")
+)

cmd/subnetter/funcs.go

@@ -6,24 +6,26 @@ import (
 	"encoding/json"
 	"encoding/xml"
 	"fmt"
-	"github.com/goccy/go-yaml"
-	"github.com/projectdiscovery/mapcidr"
-	"go4.org/netipx"
 	"io"
 	"net"
 	"net/netip"
 	"os"
 	"strings"
-	"subnetter/netsplit"
 	"time"
+
+	"github.com/goccy/go-yaml"
+	"github.com/projectdiscovery/mapcidr"
+	"go4.org/netipx"
+	"subnetter/netsplit"
+	`subnetter/version`
 )
 
 func printHostPrefix(label string, pfx *netip.Prefix, verb, indent int, indentStr string) (out string) {
 
 	var maskEvery uint
-	var sb *strings.Builder = new(strings.Builder)
-	var pre string = strings.Repeat(indentStr, indent)
-	var pre2 string = strings.Repeat(indentStr, indent+1)
+	var sb = new(strings.Builder)
+	var pre = strings.Repeat(indentStr, indent)
+	var pre2 = strings.Repeat(indentStr, indent+1)
 
 	if pfx == nil {
 		fmt.Fprintf(sb, "%s%s:\n%sAddress:\t(N/A)\n", pre, label, pre2)
@@ -102,10 +104,10 @@ func printMask(label string, pfx netip.Prefix, verb, indent int, indentStr strin
 	var mask net.IPMask
 	var first netip.Addr
 	var last netip.Addr
-	var sb *strings.Builder = new(strings.Builder)
-	var pre string = strings.Repeat(indentStr, indent)
-	var pre2 string = strings.Repeat(indentStr, indent+1)
-	var pre3 string = strings.Repeat(indentStr, indent+2)
+	var sb = new(strings.Builder)
+	var pre = strings.Repeat(indentStr, indent)
+	var pre2 = strings.Repeat(indentStr, indent+1)
+	var pre3 = strings.Repeat(indentStr, indent+2)
 
 	if !pfx.IsValid() {
 		return
@@ -156,7 +158,8 @@ func printMask(label string, pfx netip.Prefix, verb, indent int, indentStr strin
 	fmt.Fprintf(sb, "%sBits:\t\t%d\n", pre2, pfx.Bits())
 	fmt.Fprintf(sb, "%sFirst:\t\t%s\n", pre2, first.String())
 	fmt.Fprintf(sb, "%sLast:\t\t%s\n", pre2, last.String())
-	fmt.Fprintf(sb, "%sAddresses:\t%d\n", pre2, mapcidr.CountIPsInCIDR())
+	fmt.Fprintf(sb, "%sAddresses:\t%d\n", pre2, mapcidr.CountIPsInCIDR(true, true, netipx.PrefixIPNet(pfx.Masked())))
+	fmt.Fprintf(sb, "%sHosts:\t\t%d\n", pre2, mapcidr.CountIPsInCIDR(false, false, netipx.PrefixIPNet(pfx.Masked())))
 	if verb >= 2 {
 		fmt.Fprintf(sb, "%sExpanded:\t%s\n", pre2, netsplit.MaskExpand(mask, pfx.Addr().Is6()))
 		fmt.Fprintf(sb, "%sHex:\t\t0x%s\n", pre2, mask.String())
@@ -215,7 +218,7 @@ func printNets(orig *netip.Prefix, origNet *net.IPNet, nets []*netip.Prefix, rem
 	var remPfxs []*netip.Prefix
 	var invertedMask net.IPMask
 	var res *netsplit.StructuredResults
-	var verb int = -1
+	var verb = -1
 
 	if orig == nil {
 		return
@@ -341,7 +344,6 @@ func printNets(orig *netip.Prefix, origNet *net.IPNet, nets []*netip.Prefix, rem
 		}
 	} else {
 		buf = new(bytes.Buffer)
-		// TODO: data-formatted/structured output
 		if res, err = netsplit.Contain(orig, nets, remaining, splitter); err != nil {
 			return
 		}
@@ -355,11 +357,11 @@ func printNets(orig *netip.Prefix, origNet *net.IPNet, nets []*netip.Prefix, rem
 			fmt.Fprintf(
 				buf,
 				`<?xml version="1.0" encoding="UTF-8"?>`+
-					"<!--\n"+
-					"  Generated by subnetter.\n"+
+					"\n<!--\n"+
+					"  Generated by subnetter %s\n"+
 					"  %s\n"+
 					"-->\n",
-				time.Now().String(),
+				version.Ver.Short(), time.Now().String(),
 			)
 			if b, err = xml.MarshalIndent(res, "", "  "); err != nil {
 				return
@@ -368,9 +370,9 @@ func printNets(orig *netip.Prefix, origNet *net.IPNet, nets []*netip.Prefix, rem
 		case "yml":
 			fmt.Fprintf(
 				buf,
-				"# Generated by subnetter.\n"+
+				"# Generated by subnetter %s\n"+
 					"# %s\n\n",
-				time.Now().String(),
+				version.Ver.Short(), time.Now().String(),
 			)
 			if b, err = yaml.Marshal(res); err != nil {
 				return

cmd/subnetter/funcs_tblfmt.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	`fmt`
+	`strings`
+)
+
+func padStr(str string, colSize uint8) (out string) {
+
+	var fill int
+	var lFill int
+	var rFill int
+	var strLen int = len(str)
+
+	// EZPZ. Exact match.
+	if strLen+fixedPad == int(colSize) {
+		out = fmt.Sprintf(
+			"%s%s%s",
+			strings.Repeat(padChars, fixedPad/2), str, strings.Repeat(padChars, fixedPad/2),
+		)
+		return
+	}
+
+	// This is where it gets... annoying.
+	fill = int(colSize) - (strLen + fixedPad)
+	if fill%2 == 0 {
+		/*
+			Split evenly left/right.
+			This condition will be met if BOTH strLen and colSize are even,
+			or if BOTH strLen and colSize are odd.
+			Math!
+		*/
+		lFill = fill / 2
+		rFill = fill / 2
+	} else {
+		// Either the value or the width is odd, and the other is even.
+		// (Note: Goland automatically floors an int/int calculation's result.)
+		// As such, asymmetrical padding is needed.
+		if strLen%2 == 0 {
+			/*
+				String is even, width is odd.
+				Favor (smaller fill) the left.
+			*/
+			lFill = fill / 2
+			rFill = (fill + 1) / 2 // This works instead of math.Ceil because dividing by 2.
+		} else {
+			/*
+				String is odd, width is even.
+				Favor right pad.
+			*/
+			lFill = (fill + 1) / 2
+			rFill = fill / 2
+		}
+	}
+
+	out = fmt.Sprintf(
+		"%s%s%s",
+		strings.Repeat(padChars, lFill+fixedPad/2),
+		str,
+		strings.Repeat(padChars, rFill+fixedPad/2),
+	)
+
+	return
+}

cmd/subnetter/funcs_tblrows.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	`reflect`
+)
+
+// Row prints the formatted row for a tableAddr.
+func (t *tableAddr) Row(sizer *tableAddrSizer, indent string, plain bool) (out string) {
+
+	var val reflect.Value
+	var sizerVal reflect.Value
+
+	if t == nil || sizer == nil {
+		return
+	}
+	val = reflect.ValueOf(*t)
+	sizerVal = reflect.ValueOf(*sizer)
+
+	out = rowRender(val, sizerVal, indent, plain)
+	return
+}
+
+// Row prints the formatted row for a tableLegacy4.
+func (t *tableLegacy4) Row(sizer *tableLegacy4Sizer, indent string, plain bool) (out string) {
+
+	var val reflect.Value
+	var sizerVal reflect.Value
+
+	if t == nil || sizer == nil {
+		return
+	}
+	val = reflect.ValueOf(*t)
+	sizerVal = reflect.ValueOf(*sizer)
+
+	out = rowRender(val, sizerVal, indent, plain)
+	return
+}
+
+// Row prints the formatted row for a tableMask4.
+func (t *tableMask4) Row(sizer *tableMask4Sizer, indent string, plain bool) (out string) {
+
+	var val reflect.Value
+	var sizerVal reflect.Value
+
+	if t == nil || sizer == nil {
+		return
+	}
+	val = reflect.ValueOf(*t)
+	sizerVal = reflect.ValueOf(*sizer)
+
+	out = rowRender(val, sizerVal, indent, plain)
+
+	return
+}

cmd/subnetter/funcs_tblsizers.go

@@ -0,0 +1,113 @@
+package main
+
+import (
+	`reflect`
+)
+
+/*
+	Hdr prints the header for a tableAddrSizer corresponding to a slice of tableAddr.
+
+	indent will be printed before the string.
+
+	If plain is true, only ASCII chars will be used; otherwise fancy-schmancy Unicode.
+*/
+func (t *tableAddrSizer) Hdr(indent string, plain bool) (out string) {
+
+	var val reflect.Value
+
+	if t == nil {
+		return
+	}
+	val = reflect.ValueOf(*t)
+
+	out = hdrRender(val, indent, plain)
+
+	return
+}
+
+// Line either prints the *last line* (the border) or a *row separator* (if allowed in the format).
+func (t *tableAddrSizer) Line(indent string, plain bool, rowIdx, numRows int) (out string) {
+
+	var val reflect.Value
+
+	if t == nil {
+		return
+	}
+	val = reflect.ValueOf(*t)
+
+	out = hdrLineRender(val, indent, plain, rowIdx, numRows)
+
+	return
+}
+
+/*
+	Hdr prints the header for a tableLegacy4Sizer corresponding to a slice of tableLegacy4.
+
+	indent will be printed before the string.
+
+	If plain is true, only ASCII chars will be used; otherwise fancy-schmancy Unicode.
+*/
+func (t *tableLegacy4Sizer) Hdr(indent string, plain bool) (out string) {
+
+	var val reflect.Value
+
+	if t == nil {
+		return
+	}
+	val = reflect.ValueOf(*t)
+
+	out = hdrRender(val, indent, plain)
+
+	return
+}
+
+// Line either prints the *last line* (the border) or a *row separator* (if allowed in the format).
+func (t *tableLegacy4Sizer) Line(indent string, plain bool, rowIdx, numRows int) (out string) {
+
+	var val reflect.Value
+
+	if t == nil {
+		return
+	}
+	val = reflect.ValueOf(*t)
+
+	out = hdrLineRender(val, indent, plain, rowIdx, numRows)
+
+	return
+}
+
+/*
+	Hdr prints the header for a tableMask4Sizer corresponding to a slice of tableMask4.
+
+	indent will be printed before the string.
+
+	If plain is true, only ASCII chars will be used; otherwise fancy-schmancy Unicode.
+*/
+func (t *tableMask4Sizer) Hdr(indent string, plain bool) (out string) {
+
+	var val reflect.Value
+
+	if t == nil {
+		return
+	}
+	val = reflect.ValueOf(*t)
+
+	out = hdrRender(val, indent, plain)
+
+	return
+}
+
+// Line either prints the *last line* (the border) or a *row separator* (if allowed in the format).
+func (t *tableMask4Sizer) Line(indent string, plain bool, rowIdx, numRows int) (out string) {
+
+	var val reflect.Value
+
+	if t == nil {
+		return
+	}
+	val = reflect.ValueOf(*t)
+
+	out = hdrLineRender(val, indent, plain, rowIdx, numRows)
+
+	return
+}

cmd/subnetter/funcs_tpl.go

@@ -0,0 +1,447 @@
+package main
+
+import (
+	`encoding/binary`
+	`fmt`
+	`net`
+	`net/netip`
+	`reflect`
+	`strconv`
+	`strings`
+
+	`github.com/TwiN/go-color`
+	`github.com/projectdiscovery/mapcidr`
+	`go4.org/netipx`
+	`subnetter/netsplit`
+)
+
+/*
+	tplClass4Iter should only be called if legacy info is enabled.
+	It returns a tableLegacy4Sizer and a slice of tableLegacy4.
+
+	It takes no input.
+*/
+func tplClass4Iter() (legacySpec *tableLegacy4Ret, err error) {
+
+	// This whole thing feels dirty.
+	// It's like adding a microcontroller to a rock.
+	// But it works.
+	var pfx *net.IPNet
+	var classNets []*netip.Prefix
+	var netRange netipx.IPRange
+	var v *netsplit.VLSMSplitter = &netsplit.VLSMSplitter{
+		Ascending: false,
+		PrefixLengths: []uint8{
+			1, // A
+			2, // B
+			3, // C
+			4, // D
+			4, // E
+		},
+		BaseSplitter: new(netsplit.BaseSplitter),
+	}
+
+	if _, pfx, err = net.ParseCIDR("0.0.0.0/0"); err != nil {
+		return
+	}
+	v.SetParent(*pfx)
+	if classNets, _, err = v.Split(); err != nil {
+		return
+	}
+
+	legacySpec = &tableLegacy4Ret{
+		Sizer: &tableLegacy4Sizer{
+			Class: 5, // "CLASS"
+			CIDR:  4, // "BITS"
+			Start: 5, // "START"
+			End:   3, // "END"
+		},
+		Rows: make([]tableLegacy4, 5),
+	}
+	for idx, cls := range []string{
+		"A", "B", "C", "D", "E",
+	} {
+		legacySpec.Rows[idx] = tableLegacy4{
+			Class:   cls,
+			CIDR:    classNets[idx].String(),
+			NetCIDR: *classNets[idx],
+		}
+		netRange = netipx.RangeOfPrefix(legacySpec.Rows[idx].NetCIDR)
+		legacySpec.Rows[idx].NetStart = netRange.From()
+		legacySpec.Rows[idx].NetEnd = netRange.To()
+		legacySpec.Rows[idx].Start = legacySpec.Rows[idx].NetStart.String()
+		legacySpec.Rows[idx].End = legacySpec.Rows[idx].NetEnd.String()
+	}
+
+	return
+}
+
+/*
+	tplAddrIter takes a 4 or 6 for inet family/version and returns a tableAddrSizer and
+	slice of tableAddr.
+	tableAddr is sorted from smallest prefix/largest network to largest prefix/smallest network.
+*/
+func tplAddrIter(ipVer uint8) (addrs *tableAddrRet, err error) {
+
+	var dummyAddr netip.Addr
+	var dummyNet *net.IPNet
+	var l int
+
+	addrs = &tableAddrRet{
+		Sizer: &tableAddrSizer{
+			Prefix:    6, // "PREFIX"
+			Bits:      4, // "BITS"
+			Addresses: 9, // "ADDRESSES"
+			Hosts:     5, // "HOSTS"
+		},
+	}
+
+	switch ipVer {
+	case 4:
+		if dummyAddr, err = netip.ParseAddr("0.0.0.0"); err != nil {
+			return
+		}
+	case 6:
+		if dummyAddr, err = netip.ParseAddr("::"); err != nil {
+			return
+		}
+	default:
+		err = errBadNet
+		return
+	}
+
+	// Before we size, we generate the tableAddrs.
+	addrs.Rows = make([]tableAddr, dummyAddr.BitLen()+1)
+	for i := 0; i <= dummyAddr.BitLen(); i++ {
+		addrs.Rows[i] = tableAddr{
+			Prefix: uint8(i),
+			Bits:   uint8(dummyAddr.BitLen() - i),
+		}
+		if addrs.Rows[i].NetPrefix, err = dummyAddr.Prefix(i); err != nil {
+			return
+		}
+		dummyNet = netipx.PrefixIPNet(addrs.Rows[i].NetPrefix.Masked())
+		addrs.Rows[i].Addresses = mapcidr.CountIPsInCIDR(true, true, dummyNet)
+		addrs.Rows[i].Hosts = mapcidr.CountIPsInCIDR(false, false, dummyNet)
+	}
+
+	// Now the sizer. The padding itself is handled in different logic, just need the length of the longest value as a string.
+	for _, addr := range addrs.Rows {
+		// I *abhor* walrus operators in anything but loops.
+		l = len(strconv.Itoa(int(addr.Prefix)))
+		if int(addrs.Sizer.Prefix) < l {
+			addrs.Sizer.Prefix = uint8(l)
+		}
+		l = len(strconv.Itoa(int(addr.Bits)))
+		if int(addrs.Sizer.Bits) < l {
+			addrs.Sizer.Bits = uint8(l)
+		}
+		// Use the full numeric length.
+		l = len(addr.Addresses.String())
+		if int(addrs.Sizer.Addresses) < l {
+			addrs.Sizer.Addresses = uint8(l)
+		}
+		l = len(addr.Hosts.String())
+		if int(addrs.Sizer.Hosts) < l {
+			addrs.Sizer.Hosts = uint8(l)
+		}
+	}
+
+	return
+}
+
+/*
+	tplMaskIter4 returns a slice of IPv4 netmasks and returns a slice of tableMask4.
+	Sorted from smallest prefix/largest network to largest prefix/smallest network.
+*/
+func tplMaskIter4() (masks *tableMask4Ret, err error) {
+
+	var dummyAddr netip.Addr
+	var pfx netip.Prefix
+	var dummyNet *net.IPNet
+	var l int
+
+	masks = &tableMask4Ret{
+		Sizer: &tableMask4Sizer{
+			Prefix:  6, // "PREFIX"
+			Netmask: 7, // "NETMASK"
+			Hex:     3, // "HEX"
+			Dec:     3, // "DEC"
+			Bin:     3, // "BIN"
+		},
+	}
+
+	if dummyAddr, err = netip.ParseAddr("0.0.0.0"); err != nil {
+		return
+	}
+
+	masks.Rows = make([]tableMask4, dummyAddr.BitLen()+1)
+	for i := 0; i <= dummyAddr.BitLen(); i++ {
+		if pfx, err = dummyAddr.Prefix(i); err != nil {
+			return
+		}
+		dummyNet = netipx.PrefixIPNet(pfx.Masked())
+		masks.Rows[i] = tableMask4{
+			Prefix: uint8(i),
+			Netmask: netsplit.MaskFmt(
+				dummyNet.Mask,
+				"d", ".", "",
+				1, 0,
+			),
+			Hex: dummyNet.Mask.String(),
+			Dec: binary.BigEndian.Uint32(dummyNet.Mask),
+			Bin: netsplit.MaskFmt(
+				dummyNet.Mask,
+				"08b", ".", "",
+				1, 0,
+			),
+			Mask: dummyNet.Mask,
+		}
+	}
+
+	// Now the sizer.
+	for _, mask := range masks.Rows {
+		l = len(strconv.Itoa(int(mask.Prefix)))
+		if int(masks.Sizer.Prefix) < l {
+			masks.Sizer.Prefix = uint8(l)
+		}
+		l = len(mask.Netmask)
+		if int(masks.Sizer.Netmask) < l {
+			masks.Sizer.Netmask = uint8(l)
+		}
+		l = len(mask.Hex)
+		if int(masks.Sizer.Hex) < l {
+			masks.Sizer.Hex = uint8(l)
+		}
+		l = len(strconv.FormatUint(uint64(mask.Dec), 10))
+		if int(masks.Sizer.Dec) < l {
+			masks.Sizer.Dec = uint8(l)
+		}
+		l = len(mask.Bin)
+		if int(masks.Sizer.Bin) < l {
+			masks.Sizer.Bin = uint8(l)
+		}
+	}
+
+	return
+}
+
+// do not include in template funcs; used externally
+func hdrRender(hdrVal reflect.Value, indent string, plain bool) (out string) {
+
+	var val reflect.Value
+	var field reflect.StructField
+	var fieldVal reflect.Value
+	var colLen uint8
+	var colTitle string
+	var lastField int
+	var valType reflect.Type
+	var tfmt *tableFormatter = tblFmts[plain]
+	var sb *strings.Builder = new(strings.Builder)
+
+	val = hdrVal
+	valType = val.Type()
+
+	// Avoid the edge case where a struct's last field is skipped rendering
+	for i := val.NumField(); i > 0; i-- {
+		field = valType.Field(i - 1)
+		if field.Tag.Get("render") == "-" {
+			continue
+		}
+		lastField = i
+		break
+	}
+
+	// Top-most line.
+	sb.WriteString(indent)
+	sb.WriteString(tfmt.TopLeftHdr)
+	for i := 0; i < val.NumField(); i++ {
+		field = valType.Field(i)
+		if field.Tag.Get("render") == "-" {
+			continue
+		}
+		fieldVal = val.Field(i)
+		colLen = uint8(fieldVal.Uint())
+		sb.WriteString(strings.Repeat(tfmt.TopFillHdr, int(colLen)+fixedPad))
+		if i == lastField {
+			sb.WriteString(tfmt.TopRightHdr)
+		} else {
+			sb.WriteString(tfmt.TopColSepHdr)
+		}
+	}
+	sb.WriteString("\n")
+
+	// Column titles
+	sb.WriteString(indent)
+	sb.WriteString(tfmt.Left)
+	for i := 0; i < val.NumField(); i++ {
+		field = valType.Field(i)
+		if field.Tag.Get("render") == "-" {
+			continue
+		}
+		fieldVal = val.Field(i)
+		colLen = uint8(fieldVal.Uint()) + uint8(fixedPad)
+		colTitle = field.Name
+		if !tfmt.NoUpperTitle {
+			colTitle = strings.ToUpper(colTitle)
+		}
+		if !tfmt.NoBoldTitle {
+			sb.WriteString(color.InBold(padStr(colTitle, colLen)))
+		} else {
+			sb.WriteString(padStr(colTitle, colLen))
+		}
+		if i == lastField {
+			sb.WriteString(tfmt.Right)
+		} else {
+			sb.WriteString(tfmt.ColSepHdr)
+		}
+	}
+	sb.WriteString("\n")
+
+	// Header bottom line; headers always include bottom separators.
+	sb.WriteString(indent)
+	sb.WriteString(tfmt.BottomLeftHdr)
+	for i := 0; i < val.NumField(); i++ {
+		field = valType.Field(i)
+		if field.Tag.Get("render") == "-" {
+			continue
+		}
+		fieldVal = val.Field(i)
+		colLen = uint8(fieldVal.Uint())
+		sb.WriteString(strings.Repeat(tfmt.BottomFillHdr, int(colLen)+fixedPad))
+		if i == lastField {
+			sb.WriteString(tfmt.BottomRightHdr)
+		} else {
+			sb.WriteString(tfmt.BottomColSepHdr)
+		}
+	}
+	sb.WriteString("\n")
+
+	out = sb.String()
+
+	return
+}
+
+// do not include in template funcs; used externally
+func hdrLineRender(hdrVal reflect.Value, indent string, plain bool, rowIdx int, numRows int) (out string) {
+
+	var val reflect.Value
+	var field reflect.StructField
+	var fieldVal reflect.Value
+	var colLen uint8
+	var lastField int
+	var isLastLine bool
+	var valType reflect.Type
+	var tfmt *tableFormatter = tblFmts[plain]
+	var sb *strings.Builder = new(strings.Builder)
+
+	isLastLine = rowIdx == (numRows - 1)
+	if !isLastLine && tfmt.SuppressLineSep {
+		return
+	}
+
+	val = hdrVal
+	valType = val.Type()
+	lastField = valType.NumField() - 1
+
+	for i := val.NumField(); i >= 0; i-- {
+		field = valType.Field(i - 1)
+		if field.Tag.Get("render") == "-" {
+			continue
+		}
+		lastField = i
+		break
+	}
+
+	sb.WriteString(indent)
+	if isLastLine {
+		sb.WriteString(tfmt.LastLeft)
+	} else {
+		sb.WriteString(tfmt.LineLeft)
+	}
+	for i := 0; i < val.NumField(); i++ {
+		field = valType.Field(i)
+		if field.Tag.Get("render") == "-" {
+			continue
+		}
+		fieldVal = val.Field(i)
+		colLen = uint8(fieldVal.Uint())
+		if isLastLine {
+			sb.WriteString(strings.Repeat(tfmt.LastFill, int(colLen)+fixedPad))
+		} else {
+			sb.WriteString(strings.Repeat(tfmt.Fill, int(colLen)+fixedPad))
+		}
+		if i == lastField {
+			if isLastLine {
+				sb.WriteString(tfmt.LastRight)
+			} else {
+				sb.WriteString(tfmt.LineRight)
+			}
+		} else {
+			if isLastLine {
+				sb.WriteString(tfmt.LastSep)
+			} else {
+				sb.WriteString(tfmt.LineColSep)
+			}
+		}
+	}
+	sb.WriteString("\n")
+
+	out = sb.String()
+
+	return
+}
+
+// do not include in template funcs; used externally
+func rowRender(val reflect.Value, sizerVal reflect.Value, indent string, plain bool) (out string) {
+
+	var field reflect.StructField
+	var fieldVal reflect.Value
+	var colLen uint8
+	var sizerName string
+	var sizerField reflect.Value
+	var callVal string
+	var valType reflect.Type = val.Type()
+	var tfmt *tableFormatter = tblFmts[plain]
+	var sb *strings.Builder = new(strings.Builder)
+
+	sb.WriteString(indent)
+	for i := 0; i < val.NumField(); i++ {
+		field = valType.Field(i)
+		if field.Tag.Get("render") == "-" {
+			continue
+		}
+		sb.WriteString(tfmt.Left)
+		fieldVal = val.Field(i)
+		sizerName = field.Tag.Get("renderSizeName")
+		if sizerName == "" {
+			sizerName = field.Name
+		}
+		sizerField = sizerVal.FieldByName(sizerName)
+		colLen = uint8(sizerField.Uint()) + uint8(fixedPad)
+		switch fieldVal.Kind() {
+		// This is tailored specifically to this implementation.
+		case reflect.String:
+			sb.WriteString(fieldVal.String())
+		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+			sb.WriteString(padStr(fmt.Sprintf("%d", fieldVal.Int()), colLen))
+		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+			sb.WriteString(padStr(fmt.Sprintf("%d", fieldVal.Uint()), colLen))
+		case reflect.Ptr:
+			// It's a *big.Int.
+			if fieldVal.IsNil() {
+				sb.WriteString(padStr(strings.Repeat(padChars, int(colLen)), colLen))
+			} else {
+				// TIL you can even *do* this in reflection.
+				fieldVal = fieldVal.MethodByName("String").Call(nil)[0]
+				callVal = fieldVal.String()
+				sb.WriteString(padStr(callVal, colLen))
+			}
+		}
+	}
+	sb.WriteString("\n")
+
+	out = sb.String()
+
+	return
+}

cmd/subnetter/main.go

@@ -3,14 +3,17 @@ package main
 import (
 	"bytes"
 	"errors"
-	"go4.org/netipx"
+	`fmt`
 	"io"
 	"log"
 	"net"
 	"net/netip"
 	"os"
 	"strings"
+
+	"go4.org/netipx"
 	"subnetter/netsplit"
+	`subnetter/version`
 
 	"github.com/jessevdk/go-flags"
 	"r00t2.io/sysutils/paths"
@@ -29,8 +32,10 @@ func main() {
 	var remaining *netipx.IPSet
 	var buf *bytes.Buffer
 	var res *netsplit.StructuredResults
-	var splitErr *netsplit.SplitErr = new(netsplit.SplitErr)
-	var parser *flags.Parser = flags.NewParser(args, flags.Default)
+	var noStrict bool
+	var strictErr error
+	var splitErr = new(netsplit.SplitErr)
+	var parser = flags.NewParser(args, flags.Default)
 
 	if _, err = parser.Parse(); err != nil {
 		switch flagsErr := err.(type) {
@@ -46,12 +51,30 @@ func main() {
 		}
 	}
 
+	if version.Ver, err = version.Version(); err != nil {
+		log.Panicln(err)
+	}
+
+	// If args.Version or args.DetailVersion are true, just print them and exit.
+	if args.DetailVersion || args.Version {
+		if args.Version {
+			fmt.Println(version.Ver.Short())
+			return
+		} else if args.DetailVersion {
+			fmt.Println(version.Ver.Detail())
+			return
+		}
+	}
+
 	switch parser.Active.Name {
 	case "table":
-		// TODO: print table and exit
+		buf = new(bytes.Buffer)
+		if err = tblTpl.ExecuteTemplate(buf, "table.tpl", args.Table.tableOpts); err != nil {
+			log.Panicln(err)
+		}
+		os.Stdout.Write(buf.Bytes())
 		return
 	case "parse":
-		// TODO: parse file/bytes, unmarshal, and render with new options then exit
 		if strings.TrimSpace(args.Parse.InFile) == "-" {
 			buf = new(bytes.Buffer)
 			if _, err = io.Copy(buf, os.Stdin); err != nil {
@@ -102,26 +125,32 @@ func main() {
 			}
 			cmnArgs = args.SplitHost.common
 			splitter = &netsplit.HostSplitter{
-				BaseSplitter: new(netsplit.BaseSplitter),
 				NumberHosts:  args.SplitHost.Hosts,
+				Strict:       args.SplitHost.Strict,
+				BaseSplitter: new(netsplit.BaseSplitter),
 			}
+			noStrict = !args.SplitHost.Strict
+			strictErr = netsplit.ErrBadNumHosts
 		case "split-nets":
 			if err = validate.Struct(args.SplitSubnets); err != nil {
 				log.Panicln(err)
 			}
 			cmnArgs = args.SplitSubnets.common
 			splitter = &netsplit.SubnetSplitter{
-				BaseSplitter:  new(netsplit.BaseSplitter),
+				Strict:        args.SplitSubnets.Strict,
 				NumberSubnets: args.SplitSubnets.NumNets,
+				BaseSplitter:  new(netsplit.BaseSplitter),
 			}
+			noStrict = !args.SplitSubnets.Strict
+			strictErr = netsplit.ErrNoNetSpace
 		case "split-cidr":
 			if err = validate.Struct(args.SplitCIDR); err != nil {
 				log.Panicln(err)
 			}
 			cmnArgs = args.SplitCIDR.common
 			splitter = &netsplit.CIDRSplitter{
-				BaseSplitter: new(netsplit.BaseSplitter),
 				PrefixLength: args.SplitCIDR.Prefix,
+				BaseSplitter: new(netsplit.BaseSplitter),
 			}
 		case "vlsm":
 			if err = validate.Struct(args.VLSM); err != nil {
@@ -129,9 +158,9 @@ func main() {
 			}
 			cmnArgs = args.VLSM.common
 			splitter = &netsplit.VLSMSplitter{
-				BaseSplitter:  new(netsplit.BaseSplitter),
 				Ascending:     args.VLSM.Asc,
 				PrefixLengths: args.VLSM.Sizes,
+				BaseSplitter:  new(netsplit.BaseSplitter),
 			}
 		}
 		if origPfx, err = netip.ParsePrefix(cmnArgs.Network.Network); err != nil {
@@ -147,8 +176,12 @@ func main() {
 		splitter.SetParent(*pfx)
 		if nets, remaining, err = splitter.Split(); err != nil {
 			if errors.As(err, &splitErr) {
-				printSplitErr(splitErr)
-				os.Exit(1)
+				if noStrict && errors.Is(splitErr.Wrapped, strictErr) {
+					err = nil
+				} else {
+					printSplitErr(splitErr)
+					os.Exit(1)
+				}
 			} else {
 				log.Panicln(err)
 			}

cmd/subnetter/types.go

@@ -1,8 +1,134 @@
 package main
 
 import (
+	`math/big`
+	`net`
 	"net/netip"
 )
 
 // subnetResult is only used for human/"pretty" printing.
 type subnetResult netip.Prefix
+
+type tableOpts struct {
+	Plain    bool `short:"p" long:"plain" description:"Show plain table output."`
+	Legacy   bool `short:"l" long:"legacy" description:"Include legacy/obsolete/deprecated information."`
+	NoV4Mask bool `short:"M" long:"no-mask" description:"Do not include netmasks for IPv4."`
+	NoIpv6   bool `short:"4" long:"ipv4" description:"Only show IPv4 table(s)."`
+	NoIpv4   bool `short:"6" long:"ipv6" description:"Only show IPv6 table(s)."`
+}
+
+type tableAddrRet struct {
+	Sizer *tableAddrSizer
+	Rows  []tableAddr
+}
+
+type tableAddr struct {
+	Prefix    uint8
+	Bits      uint8
+	Addresses *big.Int
+	Hosts     *big.Int
+	NetPrefix netip.Prefix `render:"-"`
+}
+
+// tableAddrSizer is used to control spacing/sizing of a tableAddr table's columns.
+type tableAddrSizer struct {
+	Prefix    uint8
+	Bits      uint8
+	Addresses uint8
+	Hosts     uint8
+}
+
+type tableMask4Ret struct {
+	Sizer *tableMask4Sizer
+	Rows  []tableMask4
+}
+
+// tableMask4 is used to hold string representation of netmask information.
+type tableMask4 struct {
+	Prefix  uint8
+	Netmask string
+	Hex     string
+	Dec     uint32
+	Bin     string
+	Mask    net.IPMask `render:"-"`
+}
+
+// tableMask4Sizer, like tableAddrSizer, is used to control spacing/sizing of a tableMask4 table's columns.
+type tableMask4Sizer struct {
+	Prefix  uint8
+	Netmask uint8
+	Hex     uint8
+	Dec     uint8
+	Bin     uint8
+}
+
+type tableLegacy4Ret struct {
+	Sizer *tableLegacy4Sizer
+	Rows  []tableLegacy4
+}
+
+// tableLegacy4 contains a spec for a class in the legacy "classed" IPv4 networking.
+type tableLegacy4 struct {
+	Class    string
+	CIDR     string
+	Start    string
+	End      string
+	NetStart netip.Addr   `render:"-"`
+	NetEnd   netip.Addr   `render:"-"`
+	NetCIDR  netip.Prefix `render:"-"`
+}
+
+// tableLegacy4Sizer is used to size tableLegacy4 entries.
+type tableLegacy4Sizer struct {
+	Class uint8
+	CIDR  uint8
+	Start uint8
+	End   uint8
+}
+
+// tableFormatter is used for "rendering" table output.
+type tableFormatter struct {
+	// Headers...
+	// First char, first line
+	TopLeftHdr string
+	// Char to fill between TopLeftHdr and TopColSepHdr.
+	TopFillHdr string
+	// Column separator, first line
+	TopColSepHdr string
+	// Last char, first line
+	TopRightHdr string
+	// Column separator for both column separators (title line) and left/right-most lines.
+	ColSepHdr string
+	// First char, last line of header
+	BottomLeftHdr string
+	// Char to fill between BottomLeftHdr and BottomColSepHdr.
+	BottomFillHdr string
+	// Column separator, last line of header
+	BottomColSepHdr string
+	// Last char, last line of header
+	BottomRightHdr string
+	// Rows...
+	// Left-most line (border).
+	Left string
+	// Fill the cell lines for values
+	Fill string
+	// Separate line/cell border columns
+	LineColSep string
+	// "In-between" rows; left-most.
+	LineLeft string
+	// "In-between" rows, right-most.
+	LineRight string
+	// Separate value columns
+	ColSep string
+	// Right-most line (border)
+	Right string
+	// Last lines get special treatment as they are also a border.
+	LastLeft  string
+	LastFill  string
+	LastSep   string
+	LastRight string
+	// This is mostly for experimentation for Plain output, but...
+	SuppressLineSep bool
+	NoUpperTitle    bool
+	NoBoldTitle     bool
+}

go.mod

@@ -5,11 +5,13 @@ go 1.23.2
 toolchain go1.23.5
 
 require (
+	github.com/TwiN/go-color v1.4.1
 	github.com/go-playground/validator/v10 v10.24.0
 	github.com/goccy/go-yaml v1.15.16
 	github.com/jessevdk/go-flags v1.6.1
 	github.com/projectdiscovery/mapcidr v1.1.34
 	go4.org/netipx v0.0.0-20231129151722-fdeea329fbba
+	golang.org/x/mod v0.22.0
 	r00t2.io/sysutils v1.12.0
 )
 
@@ -19,17 +21,17 @@ require (
 	github.com/gabriel-vasile/mimetype v1.4.8 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect
 	github.com/go-playground/universal-translator v0.18.1 // indirect
-	github.com/gorilla/css v1.0.0 // indirect
+	github.com/gorilla/css v1.0.1 // indirect
 	github.com/leodido/go-urn v1.4.0 // indirect
-	github.com/microcosm-cc/bluemonday v1.0.25 // indirect
+	github.com/microcosm-cc/bluemonday v1.0.27 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/projectdiscovery/blackrock v0.0.1 // indirect
-	github.com/projectdiscovery/utils v0.0.85 // indirect
+	github.com/projectdiscovery/utils v0.4.8 // indirect
 	github.com/saintfish/chardet v0.0.0-20230101081208-5e3ef4b5456d // indirect
 	golang.org/x/crypto v0.32.0 // indirect
 	golang.org/x/net v0.34.0 // indirect
 	golang.org/x/sync v0.10.0 // indirect
 	golang.org/x/sys v0.29.0 // indirect
 	golang.org/x/text v0.21.0 // indirect
-	r00t2.io/goutils v1.7.1 // indirect
+	r00t2.io/goutils v1.7.2 // indirect
 )

go.sum

@@ -1,3 +1,5 @@
+github.com/TwiN/go-color v1.4.1 h1:mqG0P/KBgHKVqmtL5ye7K0/Gr4l6hTksPgTgMk3mUzc=
+github.com/TwiN/go-color v1.4.1/go.mod h1:WcPf/jtiW95WBIsEeY1Lc/b8aaWoiqQpu5cf8WFxu+s=
 github.com/aymerick/douceur v0.2.0 h1:Mv+mAeH1Q+n9Fr+oyamOlAkUNPWPlA8PPGR0QAaYuPk=
 github.com/aymerick/douceur v0.2.0/go.mod h1:wlT5vV2O3h55X9m7iVYN0TBM0NH/MmbLnd30/FjWUq4=
 github.com/coreos/go-systemd v0.0.0-20191104093116-d3cd4ed1dbcf/go.mod h1:F5haX7vjVVG0kc13fIWeqUViNPyEJxv/OmvnBo0Yme4=
@@ -18,14 +20,14 @@ github.com/go-playground/validator/v10 v10.24.0/go.mod h1:GGzBIJMuE98Ic/kJsBXbz1
 github.com/goccy/go-yaml v1.15.16 h1:PMTVcGI9uNPIn7KLs0H7KC1rE+51yPl5YNh4i8rGuRA=
 github.com/goccy/go-yaml v1.15.16/go.mod h1:XBurs7gK8ATbW4ZPGKgcbrY1Br56PdM69F7LkFRi1kA=
 github.com/google/uuid v1.3.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
-github.com/gorilla/css v1.0.0 h1:BQqNyPTi50JCFMTw/b67hByjMVXZRwGha6wxVGkeihY=
-github.com/gorilla/css v1.0.0/go.mod h1:Dn721qIggHpt4+EFCcTLTU/vk5ySda2ReITrtgBl60c=
+github.com/gorilla/css v1.0.1 h1:ntNaBIghp6JmvWnxbZKANoLyuXTPZ4cAMlo6RyhlbO8=
+github.com/gorilla/css v1.0.1/go.mod h1:BvnYkspnSzMmwRK+b8/xgNPLiIuNZr6vbZBTPQ2A3b0=
 github.com/jessevdk/go-flags v1.6.1 h1:Cvu5U8UGrLay1rZfv/zP7iLpSHGUZ/Ou68T0iX1bBK4=
 github.com/jessevdk/go-flags v1.6.1/go.mod h1:Mk8T1hIAWpOiJiHa9rJASDK2UGWji0EuPGBnNLMooyc=
 github.com/leodido/go-urn v1.4.0 h1:WT9HwE9SGECu3lg4d/dIA+jxlljEa1/ffXKmRjqdmIQ=
 github.com/leodido/go-urn v1.4.0/go.mod h1:bvxc+MVxLKB4z00jd1z+Dvzr47oO32F/QSNjSBOlFxI=
-github.com/microcosm-cc/bluemonday v1.0.25 h1:4NEwSfiJ+Wva0VxN5B8OwMicaJvD8r9tlJWm9rtloEg=
-github.com/microcosm-cc/bluemonday v1.0.25/go.mod h1:ZIOjCQp1OrzBBPIJmfX4qDYFuhU02nx4bn030ixfHLE=
+github.com/microcosm-cc/bluemonday v1.0.27 h1:MpEUotklkwCSLeH+Qdx1VJgNqLlpY2KXwXFM08ygZfk=
+github.com/microcosm-cc/bluemonday v1.0.27/go.mod h1:jFi9vgW+H7c3V0lb6nR74Ib/DIB5OBs92Dimizgw2cA=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
@@ -34,8 +36,8 @@ github.com/projectdiscovery/blackrock v0.0.1 h1:lHQqhaaEFjgf5WkuItbpeCZv2DUIE45k
 github.com/projectdiscovery/blackrock v0.0.1/go.mod h1:ANUtjDfaVrqB453bzToU+YB4cUbvBRpLvEwoWIwlTss=
 github.com/projectdiscovery/mapcidr v1.1.34 h1:udr83vQ7oz3kEOwlsU6NC6o08leJzSDQtls1wmXN/kM=
 github.com/projectdiscovery/mapcidr v1.1.34/go.mod h1:1+1R6OkKSAKtWDXE9RvxXtXPoajXTYX0eiEdkqlhQqQ=
-github.com/projectdiscovery/utils v0.0.85 h1:JpCVc9GJwJLNHy1MBPmAHJcE6rs7bRv72Trb3u84OHE=
-github.com/projectdiscovery/utils v0.0.85/go.mod h1:ttiPgS2LmLFd+VRBUdgfLKMMdrF98zX7z5W+K71MX40=
+github.com/projectdiscovery/utils v0.4.8 h1:/Xd38fP8xc6kifZayjrhcYALenJrjO3sHO7lg+I8ZGk=
+github.com/projectdiscovery/utils v0.4.8/go.mod h1:S314NzLcXVCbLbwYCoorAJYcnZEwv7Uhw2d3aF5fJ4s=
 github.com/saintfish/chardet v0.0.0-20230101081208-5e3ef4b5456d h1:hrujxIzL1woJ7AwssoOcM/tq5JjjG2yYOc8odClEiXA=
 github.com/saintfish/chardet v0.0.0-20230101081208-5e3ef4b5456d/go.mod h1:uugorj2VCxiV1x+LzaIdVa9b4S4qGAcH6cbhh4qVxOU=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
@@ -44,6 +46,8 @@ go4.org/netipx v0.0.0-20231129151722-fdeea329fbba h1:0b9z3AuHCjxk0x/opv64kcgZLBs
 go4.org/netipx v0.0.0-20231129151722-fdeea329fbba/go.mod h1:PLyyIXexvUFg3Owu6p/WfdlivPbZJsZdgWZlrGope/Y=
 golang.org/x/crypto v0.32.0 h1:euUpcYgM8WcP71gNpTqQCn6rC2t6ULUPiOzfWaXVVfc=
 golang.org/x/crypto v0.32.0/go.mod h1:ZnnJkOaASj8g0AjIduWNlq2NRxL0PlBrbKVyZ6V/Ugc=
+golang.org/x/mod v0.22.0 h1:D4nJWe9zXqHOmWqj4VMOJhvzj7bEZg4wEYa759z1pH4=
+golang.org/x/mod v0.22.0/go.mod h1:6SkKJ3Xj0I0BrPOZoBy3bdMptDDU9oJrpohJ3eWZ1fY=
 golang.org/x/net v0.34.0 h1:Mb7Mrk043xzHgnRM88suvJFwzVrRfHEHJEl5/71CKw0=
 golang.org/x/net v0.34.0/go.mod h1:di0qlW3YNM5oh6GqDGQr92MyTozJPmybPK4Ev/Gm31k=
 golang.org/x/sync v0.10.0 h1:3NQrjDixjgGwUOCaF8w2+VYHv0Ve/vGYSbdkTa98gmQ=
@@ -56,8 +60,8 @@ golang.org/x/text v0.21.0 h1:zyQAAkrwaneQ066sspRyJaG9VNi/YJ1NfzcGB3hZ/qo=
 golang.org/x/text v0.21.0/go.mod h1:4IBbMaMmOPCJ8SecivzSH54+73PCFmPWxNTLm+vZkEQ=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-r00t2.io/goutils v1.7.1 h1:Yzl9rxX1sR9WT0FcjK60qqOgBoFBOGHYKZVtReVLoQc=
-r00t2.io/goutils v1.7.1/go.mod h1:9ObJI9S71wDLTOahwoOPs19DhZVYrOh4LEHmQ8SW4Lk=
+r00t2.io/goutils v1.7.2 h1:dJ+pzY/U1yVi2V6eKoxe/4roM+Tb3d0umMEL9Dx4+Lw=
+r00t2.io/goutils v1.7.2/go.mod h1:9ObJI9S71wDLTOahwoOPs19DhZVYrOh4LEHmQ8SW4Lk=
 r00t2.io/sysutils v1.1.1/go.mod h1:Wlfi1rrJpoKBOjWiYM9rw2FaiZqraD6VpXyiHgoDo/o=
 r00t2.io/sysutils v1.12.0 h1:Ce3qUOyLixE1ZtFT/+SVwOT5kSkzg5+l1VloGeGugrU=
 r00t2.io/sysutils v1.12.0/go.mod h1:bNTKNBk9MnUhj9coG9JBNicSi5FrtJHEM645um85pyw=

netsplit/errs.go

@@ -4,6 +4,7 @@ import "errors"
 
 var (
 	ErrBadBoundary  error = errors.New("subnet does not align on bit boundary")
+	ErrBadNumHosts  error = errors.New("bad number of hosts; cannot split into prefix exactly")
 	ErrBadPrefix    error = errors.New("prefix is invalid")
 	ErrBadPrefixLen error = errors.New("prefix length exceeds maximum possible for prefix's inet family")
 	ErrBadSplitter  error = errors.New("invalid or unknown splitter when containing")

netsplit/funcs.go

@@ -4,11 +4,12 @@ import (
 	"encoding/json"
 	"encoding/xml"
 	"fmt"
-	"github.com/goccy/go-yaml"
-	"go4.org/netipx"
 	"net"
 	"net/netip"
 	"strings"
+
+	"github.com/goccy/go-yaml"
+	"go4.org/netipx"
 )
 
 /*
@@ -96,9 +97,9 @@ Set as 0 or `segSep` to an empty string to do no string segmentation.
 func AddrFmt(ip netip.Addr, f, sep, segSep string, every, everySeg uint) (s string) {
 
 	var numSegs int
-	var doSep bool = every > 0
-	var fs string = "%" + f
-	var sb *strings.Builder = new(strings.Builder)
+	var doSep = every > 0
+	var fs = "%" + f
+	var sb = new(strings.Builder)
 
 	if ip.IsUnspecified() || !ip.IsValid() {
 		return
@@ -152,7 +153,7 @@ func AddrInvert(ip netip.Addr) (inverted netip.Addr) {
 func Contain(origPfx *netip.Prefix, nets []*netip.Prefix, remaining *netipx.IPSet, splitter NetSplitter) (s *StructuredResults, err error) {
 
 	var rem []netip.Prefix
-	var sr StructuredResults = StructuredResults{
+	var sr = StructuredResults{
 		Original: origPfx,
 	}
 
@@ -243,9 +244,9 @@ Its parameters hold the same significance as in AddrFmt.
 func MaskFmt(mask net.IPMask, f, sep, segSep string, every, everySeg uint) (s string) {
 
 	var numSegs int
-	var doSep bool = every > 0
-	var fs string = "%" + f
-	var sb *strings.Builder = new(strings.Builder)
+	var doSep = every > 0
+	var fs = "%" + f
+	var sb = new(strings.Builder)
 
 	if mask == nil || len(mask) == 0 {
 		return

netsplit/funcs_cidrsplitter.go

@@ -1,14 +1,58 @@
 package netsplit
 
 import (
-	"go4.org/netipx"
 	"net/netip"
+
+	"go4.org/netipx"
 )
 
-// Split splits the network defined in a CIDRSplitter alongside its configuration and performs the subnetting.
+/*
+	Split splits the network defined in a CIDRSplitter alongside its configuration and performs the subnetting.
+	This strategy attempts to split a network into subnets of a single uniform explicit size.
+*/
 func (c *CIDRSplitter) Split() (nets []*netip.Prefix, remaining *netipx.IPSet, err error) {
 
-	// TODO
+	var ok bool
+	var base netip.Prefix
+	var sub netip.Prefix
+	var subPtr *netip.Prefix
+	var ipsb *netipx.IPSetBuilder = new(netipx.IPSetBuilder)
+
+	if c == nil || c.PrefixLength == 0 || c.BaseSplitter == nil || c.network == nil {
+		return
+	}
+
+	if base, ok = netipx.FromStdIPNet(c.network); !ok {
+		err = ErrBadBoundary
+		return
+	}
+	if !base.IsValid() {
+		err = ErrBadBoundary
+		return
+	}
+
+	if c.PrefixLength > uint8(base.Bits()) {
+		err = ErrBigPrefix
+		return
+	}
+
+	ipsb.AddPrefix(base)
+	if remaining, err = ipsb.IPSet(); err != nil {
+		return
+	}
+
+	for {
+		if sub, remaining, ok = remaining.RemoveFreePrefix(c.PrefixLength); !ok {
+			if !sub.IsValid() {
+				// No error; it's literally impossible since we network on boundaries.
+				// We just hit the end of the prefix.
+				break
+			}
+			subPtr = new(netip.Prefix)
+			*subPtr = sub
+			nets = append(nets, subPtr)
+		}
+	}
 
 	return
 }

netsplit/funcs_hostsplitter.go

@@ -1,14 +1,68 @@
 package netsplit
 
 import (
-	"go4.org/netipx"
+	`math/big`
+	`net`
 	"net/netip"
+
+	`github.com/projectdiscovery/mapcidr`
+	"go4.org/netipx"
 )
 
-// Split splits the network defined in a HostSplitter alongside its configuration and performs the subnetting.
+/*
+	Split splits the network defined in a HostSplitter alongside its configuration and performs the subnetting.
+	This strategy attempts to split the network into subnets of equal number of hosts.
+
+	remaining may or may not be nil depending on if the number of hosts can fit cleanly within equal network sizes on boundaries.
+
+	An ErrBadNumHosts will be returned if the number of hosts does not match the *addressable* range in a prefix.
+*/
 func (h *HostSplitter) Split() (nets []*netip.Prefix, remaining *netipx.IPSet, err error) {
 
-	// TODO
+	var tgt *big.Int
+	var hosts *big.Int
+	var sub netip.Prefix
+	var subPtr *netip.Prefix
+	var split []*net.IPNet
+	var ipsb *netipx.IPSetBuilder = new(netipx.IPSetBuilder)
+
+	if h == nil || h.NumberHosts == 0 || h.BaseSplitter == nil || h.network == nil {
+		return
+	}
+
+	if split, err = mapcidr.SplitIPNetByNumber(h.network, int(h.NumberHosts)); err != nil {
+		return
+	}
+
+	tgt = big.NewInt(0)
+	tgt.SetUint64(uint64(h.NumberHosts))
+
+	nets = make([]*netip.Prefix, len(split))
+	for idx, n := range split {
+		sub, _ = netipx.FromStdIPNet(n)
+		hosts = mapcidr.CountIPsInCIDR(false, false, n)
+		if hosts == nil || tgt.Cmp(hosts) != 0 {
+			err = &SplitErr{
+				Wrapped:            ErrBadNumHosts,
+				Nets:               nets,
+				Remaining:          remaining,
+				LastSubnet:         &sub,
+				RequestedPrefixLen: uint8(sub.Bits()),
+			}
+			ipsb.AddPrefix(sub)
+		} else {
+			subPtr = new(netip.Prefix)
+			*subPtr = sub
+			nets = append(nets, subPtr)
+		}
+
+		nets[idx] = new(netip.Prefix)
+		*nets[idx] = sub
+	}
+
+	if remaining, err = ipsb.IPSet(); err != nil {
+		return
+	}
 
 	return
 }

netsplit/funcs_structuredresults.go

@@ -1,8 +1,9 @@
 package netsplit
 
 import (
-	"go4.org/netipx"
 	"net/netip"
+
+	"go4.org/netipx"
 )
 
 /*

netsplit/funcs_subnetsplitter.go

@@ -1,14 +1,106 @@
 package netsplit
 
 import (
-	"go4.org/netipx"
+	`net`
 	"net/netip"
+
+	`github.com/projectdiscovery/mapcidr`
+	"go4.org/netipx"
 )
 
-// Split splits the network defined in a SubnetSplitter alongside its configuration and performs the subnetting.
+/*
+	Split splits the network defined in a SubnetSplitter alongside its configuration and performs the subnetting.
+	This strategy allows for splitting a network into exactly evenly sized specified number of subnets.
+
+	remaining may or may not be nil depending on if the specified number of subnets fit cleanly into the network boundaries.
+
+	An ErrNoNetSpace error will be returned if subnetting size exhaustion occurs before the specified number of subnets is reached
+	(but nets will be populated and remaining will contain any left over subnets).
+*/
 func (s *SubnetSplitter) Split() (nets []*netip.Prefix, remaining *netipx.IPSet, err error) {
 
-	// TODO
+	var ok bool
+	var pfxLen int
+	var base netip.Prefix
+	var sub netip.Prefix
+	var subPtr *netip.Prefix
+	var split []*net.IPNet
+	var ipsb *netipx.IPSetBuilder = new(netipx.IPSetBuilder)
+
+	if s == nil || s.BaseSplitter == nil || s.network == nil || s.NumberSubnets == 0 {
+		return
+	}
+
+	if base, ok = netipx.FromStdIPNet(s.network); !ok {
+		err = ErrBadBoundary
+		return
+	}
+	if !base.IsValid() {
+		err = ErrBadBoundary
+		return
+	}
+
+	if split, err = mapcidr.SplitIPNetIntoN(s.network, int(s.NumberSubnets)); err != nil {
+		return
+	}
+
+	for _, n := range split {
+		if sub, ok = netipx.FromStdIPNet(n); !ok {
+			// We bail early on this error.
+			err = &SplitErr{
+				Wrapped:            ErrBadBoundary,
+				Nets:               nets,
+				Remaining:          remaining,
+				LastSubnet:         subPtr,
+				RequestedPrefixLen: 0,
+			}
+			err = ErrBadBoundary
+			return
+		}
+		if sub.String() == base.String() {
+			continue
+		}
+		if pfxLen == 0 {
+			pfxLen = sub.Bits()
+			if nets == nil {
+				nets = make([]*netip.Prefix, 0)
+			}
+			subPtr = new(netip.Prefix)
+			*subPtr = sub
+			nets = append(nets, subPtr)
+		} else {
+			if sub.Bits() != pfxLen {
+				if err == nil {
+					// Return this err but don't return early; wait for the populate.
+					err = &SplitErr{
+						Wrapped:            ErrNoNetSpace,
+						Nets:               nets,
+						Remaining:          remaining,
+						LastSubnet:         subPtr,
+						RequestedPrefixLen: uint8(pfxLen),
+					}
+				}
+				ipsb.AddPrefix(sub)
+			} else {
+				subPtr = new(netip.Prefix)
+				*subPtr = sub
+				nets = append(nets, subPtr)
+			}
+		}
+	}
+
+	if remaining, err = ipsb.IPSet(); err != nil {
+		return
+	}
+
+	if len(nets) < int(s.NumberSubnets) {
+		err = &SplitErr{
+			Wrapped:   ErrNoNetSpace,
+			Nets:      nets,
+			Remaining: remaining,
+		}
+		return
+	}
 
 	return
 }

netsplit/funcs_vlsmsplitter.go

@@ -1,12 +1,18 @@
 package netsplit
 
 import (
-	"go4.org/netipx"
 	"net/netip"
 	"sort"
+
+	"go4.org/netipx"
 )
 
-// Split splits the network defined in a VLSMSplitter alongside its configuration and performs the subnetting.
+/*
+	Split splits the network defined in a VLSMSplitter alongside its configuration and performs the subnetting.
+	This strategy allows for multiple subnets of differing sizes to be specified.
+
+	remaining may or may not be nil depending on if all desired subnet sizes fit cleanly into the network boundaries.
+*/
 func (v *VLSMSplitter) Split() (nets []*netip.Prefix, remaining *netipx.IPSet, err error) {
 
 	var ok bool
@@ -15,7 +21,7 @@ func (v *VLSMSplitter) Split() (nets []*netip.Prefix, remaining *netipx.IPSet, e
 	var base netip.Prefix
 	var sub netip.Prefix
 	var subPtr *netip.Prefix
-	var ipsb *netipx.IPSetBuilder = new(netipx.IPSetBuilder)
+	var ipsb = new(netipx.IPSetBuilder)
 
 	if err = ValidateSizes(v.network, v.PrefixLengths...); err != nil {
 		return

netsplit/init.go

@@ -0,0 +1,3 @@
+package netsplit
+
+// TODO?

netsplit/types.go

@@ -2,9 +2,10 @@ package netsplit
 
 import (
 	"encoding/xml"
-	"go4.org/netipx"
 	"net"
 	"net/netip"
+
+	"go4.org/netipx"
 )
 
 // SplitErr is used to wrap an error with context surrounding when/how that error was encountered.
@@ -48,7 +49,9 @@ It attempts to evenly distribute addresses amoungs subnets.
 */
 type HostSplitter struct {
 	// NumberHosts is the number of hosts to be placed in each subnet to split out.
-	NumberHosts   uint `json:"hosts" xml:"hosts,attr" yaml:"Number of Hosts Per Subnet"`
+	NumberHosts uint `json:"hosts" xml:"hosts,attr" yaml:"Number of Hosts Per Subnet"`
+	// Strict, if true, will return an error from Split if the network cannot split into subnets of NumberHosts-addressable networks exactly.
+	Strict        bool `json:"strict" xml:"strict,attr,omitempty" yaml:"Strictly Equal Hosts Per Subnet"`
 	*BaseSplitter `json:"net" xml:"net,omitempty" yaml:"network,omitempty"`
 }
 
@@ -59,6 +62,8 @@ as cleanly as poossible.
 type SubnetSplitter struct {
 	// NumberSubnets indicates the number of subnets to split the network into.
 	NumberSubnets uint `json:"nets" xml:"nets,attr" yaml:"Number of Target Subnets"`
+	// Strict, if true, will return an error from Split if the network sizes cannot split into equally-sized networks.
+	Strict        bool `json:"strict" xml:"strict,attr,omitempty" yaml:"Strictly Equal Subnet Sizes"`
 	*BaseSplitter `json:"net" xml:"net,omitempty" yaml:"network,omitempty"`
 }
 

version/consts.go

@@ -0,0 +1,63 @@
+/*
+ * BSD 3-Clause License
+ * Copyright (c) 2024, NetFire™ <https://netfire.com/>
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ *  are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *  list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *  this list of conditions and the following disclaimer in the documentation
+ *  and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ *  may be used to endorse or promote products derived from this software without
+ *  specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ *  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ *  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ *  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ *  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ *  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ *  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ *  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package version
+
+import (
+	"regexp"
+)
+
+/*
+These variables are automatically handled by the build script.
+
+DO NOT MODIFY THESE VARIABLES.
+Refer to /build.sh for how these are generated at build time and populated.
+*/
+var (
+	sourceControl      string = "git"
+	repoUri            string = "(unknown)"
+	version            string = "(unknown)"
+	commitHash         string
+	commitShort        string
+	numCommitsAfterTag string
+	isDirty            string
+	buildTime          string
+	buildUser          string
+	buildSudoUser      string
+	buildHost          string
+)
+
+var (
+	patchRe         *regexp.Regexp = regexp.MustCompile(`^(?P<patch>[0-9+])(?P<pre>-[0-9A-Za-z.-]+)?(?P<build>\+[0-9A-Za-z.-]+)?$`)
+	patchReIsolated *regexp.Regexp = regexp.MustCompile(`^([0-9]+)(?:[-+](.*)?)?$`)
+)
+
+// Ver is populated by main() from the build script and used in other places.
+var Ver *BuildInfo

version/funcs.go

@@ -0,0 +1,180 @@
+/*
+ * BSD 3-Clause License
+ * Copyright (c) 2024, NetFire™ <https://netfire.com/>
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ *  are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *  list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *  this list of conditions and the following disclaimer in the documentation
+ *  and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ *  may be used to endorse or promote products derived from this software without
+ *  specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ *  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ *  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ *  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ *  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ *  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ *  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ *  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package version
+
+import (
+	`fmt`
+	`runtime`
+	`strconv`
+	`strings`
+	`time`
+
+	`golang.org/x/mod/semver`
+)
+
+// Version returns the build information. See build.sh.
+func Version() (b *BuildInfo, err error) {
+
+	var n int
+	var s string
+	var sb strings.Builder
+	var ok bool
+	var canonical string
+	var build strings.Builder
+	// Why a map?
+	// I forget but I had a reason for it once upon a time.
+	// If you remove it and this func breaks, now you know why.
+	// TODO: how much of this can be replaced by (runtime/debug).ReadBuildInfo()?
+	var raw map[string]string = map[string]string{
+		"repoUri":        repoUri,
+		"sourceControl":  sourceControl,
+		"tag":            version,
+		"hash":           commitHash,
+		"shortHash":      commitShort,
+		"postTagCommits": numCommitsAfterTag,
+		"dirty":          isDirty,
+		"time":           buildTime,
+		"user":           buildUser,
+		"sudoUser":       buildSudoUser,
+		"host":           buildHost,
+	}
+	var i BuildInfo = BuildInfo{
+		SourceControl: raw["sourceControl"],
+		GoVersion:     runtime.Version(),
+		RepoURI:       raw["repoUri"],
+		TagVersion:    raw["tag"],
+		// PostTagCommits: 0,
+		CommitHash:    raw["hash"],
+		CommitId:      raw["shortHash"],
+		BuildUser:     raw["user"],
+		RealBuildUser: raw["sudoUser"],
+		// BuildTime:     time.Time{},
+		BuildHost: raw["host"],
+		Dirty:     false,
+		isDefined: false,
+		raw:       raw,
+	}
+
+	if s, ok = raw["postTagCommits"]; ok && strings.TrimSpace(s) != "" {
+		if n, err = strconv.Atoi(s); err == nil {
+			i.PostTagCommits = uint(n)
+		}
+	}
+
+	if s, ok = raw["time"]; ok && strings.TrimSpace(s) != "" {
+		if n, err = strconv.Atoi(s); err == nil {
+			i.BuildTime = time.Unix(int64(n), 0).UTC()
+		}
+	}
+
+	switch strings.ToLower(raw["dirty"]) {
+	case "1":
+		i.Dirty = true
+	case "0", "":
+		i.Dirty = false
+	}
+
+	// Build the short form. We use this for both BuildInfo.short and BuildInfo.verSplit.
+	if i.TagVersion == "" {
+		sb.WriteString(i.SourceControl)
+	} else {
+		sb.WriteString(i.TagVersion)
+	}
+	/*
+		Now the mess. In order to conform to SemVer 2.0 (the spec this code targets):
+
+		1.) MAJOR.
+		2.) MINOR.
+		3.) PATCH
+		4.) -PRERELEASE (OPTIONAL)
+			(git commit, if building against a commit made past 1-3. Always included if untagged.)
+		5.) +BUILDINFO (OPTIONAL)
+			("+x[.y]", where x is # of commits past 4, or tag commit if 4 is empty. 0 is valid.
+			 y is optional, and is the string "dirty" if it is a "dirty" build - that is, uncommitted/unstaged changes.
+			 if x and y would be 0 and empty, respectively, then 5 is not included.)
+
+		1-3 are already written, or the source control software used if not.
+
+		Technically 4 and 5 are only included if 3 is present. We force patch to 0 if it's a tagged release and patch isn't present --
+		so this is not relevant.
+	*/
+	// PRERELEASE
+	if i.TagVersion == "" || i.PostTagCommits > 0 {
+		// We use the full commit hash for git versions, short identifier for tagged releases.
+		if i.TagVersion == "" {
+			i.Pre = i.CommitHash
+		} else {
+			i.Pre = i.CommitId
+		}
+		sb.WriteString(fmt.Sprintf("-%v", i.Pre))
+	}
+	// BUILD
+	if i.PostTagCommits > 0 || i.Dirty {
+		build.WriteString(strconv.Itoa(int(i.PostTagCommits)))
+		if i.Dirty {
+			build.WriteString(".dirty")
+		}
+		i.Build = build.String()
+		sb.WriteString(fmt.Sprintf("+%v", i.Build))
+	}
+
+	i.short = sb.String()
+	if semver.IsValid(i.short) {
+		// DON'T DO THIS. It strips the prerelease and build info.
+		// i.short = semver.Canonical(i.short)
+		// Do this instead.
+		canonical = semver.Canonical(i.short)
+		// Numeric versions...
+		if n, err = strconv.Atoi(strings.TrimPrefix(semver.Major(canonical), "v")); err != nil {
+			err = nil
+		} else {
+			i.Major = uint(n)
+		}
+		if n, err = strconv.Atoi(strings.Split(semver.MajorMinor(canonical), ".")[1]); err != nil {
+			err = nil
+		} else {
+			i.Minor = uint(n)
+		}
+		if n, err = strconv.Atoi(patchReIsolated.FindStringSubmatch(strings.Split(canonical, ".")[2])[1]); err != nil {
+			err = nil
+		} else {
+			i.Patch = uint(n)
+		}
+		// The other tag assignments were performed above.
+	}
+	// The default is 0 for the numerics, so no big deal.
+
+	i.isDefined = true
+
+	b = &i
+
+	return
+}

version/funcs_buildinfo.go

@@ -0,0 +1,133 @@
+/*
+ * BSD 3-Clause License
+ * Copyright (c) 2024, NetFire™ <https://netfire.com/>
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ *  are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *  list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *  this list of conditions and the following disclaimer in the documentation
+ *  and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ *  may be used to endorse or promote products derived from this software without
+ *  specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ *  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ *  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ *  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ *  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ *  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ *  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ *  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package version
+
+import (
+	`fmt`
+	`strings`
+
+	`golang.org/x/mod/semver`
+)
+
+// Detail returns a multiline string containing every possible piece of information we collect.
+func (b *BuildInfo) Detail() (ver string) {
+
+	var sb strings.Builder
+
+	sb.WriteString(fmt.Sprintf("%v\n\n", b.short))
+	sb.WriteString(fmt.Sprintf("====\nSource Control: %v\nRepo URI: %v\n", b.SourceControl, b.RepoURI))
+	if b.TagVersion != "" {
+		if b.PostTagCommits > 0 {
+			sb.WriteString(fmt.Sprintf("Version Base: %v\nCommit Hash: %v\n", b.TagVersion, b.CommitHash))
+		} else {
+			sb.WriteString(fmt.Sprintf("Version: %v\n", b.TagVersion))
+		}
+	} else {
+		sb.WriteString(fmt.Sprintf("Version: (Unversioned)\nCommit Hash: %v\n", b.CommitHash))
+	}
+
+	// Post-commits
+	if b.TagVersion != "" {
+		sb.WriteString(fmt.Sprintf("# of Commits Since %v: %v\n", b.TagVersion, b.PostTagCommits))
+	} else {
+		sb.WriteString(fmt.Sprintf("# of Commits Since %v: %v\n", b.CommitId, b.PostTagCommits))
+	}
+
+	sb.WriteString("Uncommitted/Unstaged Changes: ")
+	if b.Dirty {
+		sb.WriteString("yes (dirty/monkeypatched build)\n")
+	} else {
+		sb.WriteString("no (clean build)\n")
+	}
+
+	if b.TagVersion != "" {
+		sb.WriteString(
+			fmt.Sprintf(
+				"====\nMajor: %v\nMinor: %v\nPatch: %v\n",
+				b.Major, b.Minor, b.Patch,
+			),
+		)
+	}
+	sb.WriteString("====\n")
+	sb.WriteString(b.Meta())
+
+	ver = sb.String()
+
+	return
+}
+
+// Short returns a uniquely identifiable version string.
+func (b *BuildInfo) Short() (ver string) {
+
+	ver = b.short
+
+	return
+}
+
+// Meta returns the build/compile-time info.
+func (b *BuildInfo) Meta() (meta string) {
+
+	var sb strings.Builder
+
+	if b.RealBuildUser != b.BuildUser && b.RealBuildUser != "" {
+		sb.WriteString(fmt.Sprintf("Real Build User: %v\n", b.RealBuildUser))
+		sb.WriteString(fmt.Sprintf("Sudo Build User: %v\n", b.BuildUser))
+	} else {
+		sb.WriteString(fmt.Sprintf("Build User: %v\n", b.BuildUser))
+	}
+	sb.WriteString(fmt.Sprintf("Build Time: %v\nBuild Host: %v\nGo Version: %v\n", b.BuildTime, b.BuildHost, b.GoVersion))
+
+	meta = sb.String()
+
+	return
+}
+
+// getReMap gets a regex map of map[pattern]match.
+func (b *BuildInfo) getReMap() (matches map[string]string) {
+
+	var s string = b.Short()
+	var sections []string
+
+	if !semver.IsValid(s) {
+		return
+	}
+
+	sections = strings.Split(s, ".")
+
+	// The split should contain everything in the third element.
+	// Or, if using a "simplified" semver, the last element.
+	matches = make(map[string]string)
+	for idx, str := range patchRe.FindStringSubmatch(sections[len(sections)-1]) {
+		matches[patchRe.SubexpNames()[idx]] = str
+	}
+
+	return
+}

version/types.go

@@ -0,0 +1,85 @@
+/*
+ * BSD 3-Clause License
+ * Copyright (c) 2024, NetFire™ <https://netfire.com/>
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ *  are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *  list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *  this list of conditions and the following disclaimer in the documentation
+ *  and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ *  may be used to endorse or promote products derived from this software without
+ *  specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ *  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ *  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ *  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ *  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ *  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ *  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ *  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package version
+
+import (
+	`time`
+)
+
+// BuildInfo contains nativized version information.
+type BuildInfo struct {
+	// RepoURI is where the source is from.
+	RepoURI string
+	// GoVersion is the version of the Go compiler used.
+	GoVersion string
+	// TagVersion is the most recent tag name on the current branch.
+	TagVersion string
+	// PostTagCommits is the number of commits after BuildInfo.TagVersion's commit on the current branch.
+	PostTagCommits uint
+	// CommitHash is the full commit hash.
+	CommitHash string
+	// CommitId is the "short" version of BuildInfo.CommitHash.
+	CommitId string
+	// BuildUser is the user the program was compiled under.
+	BuildUser string
+	// If compiled under sudo, BuildInfo.RealBuildUser is the user that called sudo.
+	RealBuildUser string
+	// BuildTime is the time and date of the program's build time.
+	BuildTime time.Time
+	// BuildHost is the host the binary was compiled on.
+	BuildHost string
+	// Dirty specifies if the source was "dirty" (uncommitted/unstaged etc. files) at the time of compilation.
+	Dirty bool
+	// SourceControl is the source control version used. Only relevant if not a "clean" build or untagged.
+	SourceControl string
+	// Major is the major version, expressed as an uint per spec.
+	Major uint
+	// Minor is the minor version, expressed as an uint per spec.
+	Minor uint
+	// Patch is the patch version, expressed as an uint per spec.
+	Patch uint
+	// Pre
+	Pre string
+	// Build
+	Build string
+	// isDefined specifies if this version was retrieved from the built-in values.
+	isDefined bool
+	// raw is the raw variable values.
+	raw map[string]string
+	/*
+		verSplit is a slice of []string{Major, Minor, Patch, PreRelease, Build}
+
+		If using an actual point release, PreRelease and Build are probably blank.
+	*/
+	verSplit [5]string
+	// short is the condensed version of verSplit.
+	short string
+}