v0.2.4

FIXED: * IPv6 split-nets splitter didn't work. It does not. https://github.com/projectdiscovery/mapcidr/issues/628 Noticed. As such, this library/program has *completely removed* ALL use of the mapcidr library as it cannot be expected to be accurate.
v0.2.3
2025-04-13 03:52:43 -04:00 · 2025-04-07 16:03:20 -04:00
5 changed files with 317 additions and 71 deletions
--- a/8
+++ b/8
@@ -0,0 +1,8 @@
+The "IPv6 Segment Reference Diagram" output as rendered in the `table`
+subcommand is from:
+	https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing
+as fetched on April 07, 2025.
+It is licensed under Creative Commons "CC BY-SA 4.0";
+see:
+	https://creativecommons.org/licenses/by-sa/4.0/
+	https://creativecommons.org/licenses/by-sa/4.0/legalcode.en)
--- a/cmd/subnetter/_tpl/table.tpl
+++ b/cmd/subnetter/_tpl/table.tpl
@@ -47,13 +47,268 @@ IPV4:
 {{- end }}

 {{- if not $opts.NoIpv6 }}
-
 	{{- if $opts.Plain }}
 IPV6:
 	{{- else }}
 {{ bold "IPv6:"}}
 	{{- end }}
+	{{- if not $opts.NoIpv6Seg }}
 		{{- if $opts.Plain }}
+	IPv6 Segment Reference Diagram:
+			{{- if $opts.VertSeg }}
+
+		Example:	2001:0db8:0123:4567:89ab:cdef:1234:5678
+				{{- if not $opts.VertInvert }}
+		2								4
+		0								8
+		0								12
+		1								16
+		:
+			0							20
+			d							24
+			b							28
+			8							32
+			:
+				0						36
+				1						40
+				2						44
+				3						48
+				:
+					4					52
+					5					56
+					6					60
+					7					64
+					:
+						8				68
+						9				72
+						a				76
+						b				80
+						:
+							c			84
+							d			88
+							e			92
+							f			96
+							:
+								1		100
+								2		104
+								3		108
+								4	 	112
+								:
+									5	116
+									6	120
+									7	124
+									8	127 or 128
+				{{- else }}
+		4 ____ 2
+		8 ____ 0
+		12 ___ 0
+		16 ___ 1
+		   ___ :
+		20 _____ 0
+		24 _____ d
+		28 _____ b
+		32 _____ 8
+		   _____ :
+		36 _______ 0
+		40 _______ 1
+		44 _______ 2
+		48 _______ 3
+		   _______ :
+		52 _________ 4
+		56 _________ 5
+		60 _________ 6
+		64 _________ 7
+		   _________ :
+		68 ___________ 8
+		72 ___________ 9
+		76 ___________ a
+		80 ___________ b
+		   ___________ :
+		84 _____________ c
+		88 _____________ d
+		92 _____________ e
+		96 _____________ f
+		   _____________ :
+		100 ______________ 1
+		104 ______________ 2
+		108 ______________ 3
+		112 ______________ 4
+		    ______________ :
+		116 ________________ 5
+		120 ________________ 6
+		124 ________________ 7
+		127 ________________ (8)
+		128 ________________ (8)
+				{{- end }}
+			{{- else }}
+
+		2001:0db8:0123:4567:89ab:cdef:1234:5678
+		|||| |||| |||| |||| |||| |||| |||| ||||
+		|||| |||| |||| |||| |||| |||| |||| |||128
+		|||| |||| |||| |||| |||| |||| |||| |||127
+		|||| |||| |||| |||| |||| |||| |||| ||124
+		|||| |||| |||| |||| |||| |||| |||| |120
+		|||| |||| |||| |||| |||| |||| |||| 116
+		|||| |||| |||| |||| |||| |||| |||112
+		|||| |||| |||| |||| |||| |||| ||108
+		|||| |||| |||| |||| |||| |||| |104
+		|||| |||| |||| |||| |||| |||| 100
+		|||| |||| |||| |||| |||| |||96
+		|||| |||| |||| |||| |||| ||92
+		|||| |||| |||| |||| |||| |88
+		|||| |||| |||| |||| |||| 84
+		|||| |||| |||| |||| |||80
+		|||| |||| |||| |||| ||76
+		|||| |||| |||| |||| |72
+		|||| |||| |||| |||| 68
+		|||| |||| |||| |||64
+		|||| |||| |||| ||60
+		|||| |||| |||| |56
+		|||| |||| |||| 52
+		|||| |||| |||48
+		|||| |||| ||44
+		|||| |||| |40
+		|||| |||| 36
+		|||| |||32
+		|||| ||28
+		|||| |24
+		|||| 20
+		|||16
+		||12
+		|8
+		4
+			{{- end }}
+		{{- else }}
+	{{ bold "IPv6 Segment Reference Diagram:" }}
+			{{- if $opts.VertSeg }}
+
+		{{ bold "Example:"}}	2001:0db8:0123:4567:89ab:cdef:1234:5678
+				{{- if not $opts.VertInvert }}
+		2								4
+		0								8
+		0								12
+		1								16
+		:
+			0							20
+			d							24
+			b							28
+			8							32
+			:
+				0						36
+				1						40
+				2						44
+				3						48
+				:
+					4					52
+					5					56
+					6					60
+					7					64
+					:
+						8				68
+						9				72
+						a				76
+						b				80
+						:
+							c			84
+							d			88
+							e			92
+							f			96
+							:
+								1		100
+								2		104
+								3		108
+								4	 	112
+								:
+									5	116
+									6	120
+									7	124
+									8	127 or 128
+				{{- else }}
+		4 ━━━━ 2
+		8 ━━━━ 0
+		12 ━━━ 0
+		16 ━━━ 1
+		   ━━━ :
+		20 ━━━━━ 0
+		24 ━━━━━ d
+		28 ━━━━━ b
+		32 ━━━━━ 8
+		   ━━━━━ :
+		36 ━━━━━━━ 0
+		40 ━━━━━━━ 1
+		44 ━━━━━━━ 2
+		48 ━━━━━━━ 3
+		   ━━━━━━━ :
+		52 ━━━━━━━━━ 4
+		56 ━━━━━━━━━ 5
+		60 ━━━━━━━━━ 6
+		64 ━━━━━━━━━ 7
+		   ━━━━━━━━━ :
+		68 ━━━━━━━━━━━ 8
+		72 ━━━━━━━━━━━ 9
+		76 ━━━━━━━━━━━ a
+		80 ━━━━━━━━━━━ b
+		   ━━━━━━━━━━━ :
+		84 ━━━━━━━━━━━━━ c
+		88 ━━━━━━━━━━━━━ d
+		92 ━━━━━━━━━━━━━ e
+		96 ━━━━━━━━━━━━━ f
+		   ━━━━━━━━━━━━━ :
+		100 ━━━━━━━━━━━━━━ 1
+		104 ━━━━━━━━━━━━━━ 2
+		108 ━━━━━━━━━━━━━━ 3
+		112 ━━━━━━━━━━━━━━ 4
+		    ━━━━━━━━━━━━━━ :
+		116 ━━━━━━━━━━━━━━━━ 5
+		120 ━━━━━━━━━━━━━━━━ 6
+		124 ━━━━━━━━━━━━━━━━ 7
+		127 ━━━━━━━━━━━━━━━━ (8)
+		128 ━━━━━━━━━━━━━━━━ (8)
+				{{- end }}
+			{{- else }}
+
+		{{ bold "2001:0db8:0123:4567:89ab:cdef:1234:5678" }}
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃128
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃127
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃124
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃120
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ 116
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃112
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃108
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃104
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ 100
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃96
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃92
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃88
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ 84
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃80
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃76
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃72
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃┃ 68
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃┃64
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃┃60
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ ┃56
+		┃┃┃┃ ┃┃┃┃ ┃┃┃┃ 52
+		┃┃┃┃ ┃┃┃┃ ┃┃┃48
+		┃┃┃┃ ┃┃┃┃ ┃┃44
+		┃┃┃┃ ┃┃┃┃ ┃40
+		┃┃┃┃ ┃┃┃┃ 36
+		┃┃┃┃ ┃┃┃32
+		┃┃┃┃ ┃┃28
+		┃┃┃┃ ┃24
+		┃┃┃┃ 20
+		┃┃┃16
+		┃┃12
+		┃8
+		4
+			{{- end }}
+		{{- end }}
+	{{- end }}
+
+
+	{{- if $opts.Plain }}
+
 	CIDR:
 	{{- else }}
 	{{ bold "CIDR:" }}
--- a/cmd/subnetter/args.go
+++ b/cmd/subnetter/args.go
@@ -77,7 +77,7 @@ type SplitHostArgs struct {
 }

 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."`
+	Strict  bool `short:"t" long:"strict" description:"If specified, an error will occur if the number of subnets is not exactly -n/--num-nets."`
 	NumNets uint `short:"n" long:"num-nets" required:"true" description:"Number of networks." validate:"required"`
 	splitArgs
 }
@@ -89,6 +89,9 @@ type TableArgs struct {
 	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)."`
+	NoIpv6Seg  bool `short:"D" long:"no-ipv6-seg" description:"Do not show the IPv6 Segment Reference Diagram (ignored if -4/--ipv4 is specified)."`
+	VertSeg    bool `short:"V" long:"vert-ipv6-seg" description:"If specified, display the IPv6 Segment Reference Diagram vertically-aligned instead of horizontally."`
+	VertInvert bool `short:"I" long:"vert-invert" description:"When printing a vertical-aligned IPv6 Segment Reference Diagram, flip so the prefix length is on the left. This takes up less width and is recommended for smaller terminals, and may be easier to read in general."`
 }

 type CheckArgs struct {
--- a/netsplit/errs.go
+++ b/netsplit/errs.go
@@ -5,6 +5,7 @@ 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")
+	ErrBadNumNets   error = errors.New("bad number of nets; 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")
--- a/netsplit/funcs_subnetsplitter.go
+++ b/netsplit/funcs_subnetsplitter.go
@@ -1,10 +1,9 @@
 package netsplit

 import (
-	`net`
+	`math`
 	"net/netip"

-	`github.com/projectdiscovery/mapcidr`
 	"go4.org/netipx"
 )

@@ -22,10 +21,7 @@ func (s *SubnetSplitter) Split() (nets []*netip.Prefix, remaining *netipx.IPSet,
 	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)
+	var vlsm *VLSMSplitter

 	if s == nil || s.BaseSplitter == nil || s.network == nil || s.NumberSubnets == 0 {
 		return
@@ -40,65 +36,48 @@ func (s *SubnetSplitter) Split() (nets []*netip.Prefix, remaining *netipx.IPSet,
 		return
 	}

-	if split, err = mapcidr.SplitIPNetIntoN(s.network, int(s.NumberSubnets)); err != nil {
-		return
-	}
+	// Previously, this used (github.com/projectdiscovery/mapcidr).SplitIPNetIntoN.
+	// It no longer does: https://github.com/projectdiscovery/mapcidr/issues/628
+	// I am Noticing.

-	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
+	// First the number of bits needed is calculated.
+	pfxLen = int(math.Ceil(math.Log2(float64(s.NumberSubnets))))
+	// And this is then added to the original prefix length to get the new prefix size.
+	pfxLen = pfxLen + base.Bits()
+	// I don't know how this would happen, but it'd be bad if it did.
+	if pfxLen < base.Bits() {
+		err = ErrBigPrefix
 		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)
+	// Likewise.
+	if base.Addr().Is6() {
+		ok = pfxLen <= int(maxBitsv6)
 	} 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),
+		ok = pfxLen <= int(maxBitsv4)
 	}
-				}
-				ipsb.AddPrefix(sub)
-			} else {
-				subPtr = new(netip.Prefix)
-				*subPtr = sub
-				nets = append(nets, subPtr)
-			}
-		}
-	}
-
-	if remaining, err = ipsb.IPSet(); err != nil {
+	if !ok {
+		err = ErrBadPrefix
 		return
 	}

-	if len(nets) < int(s.NumberSubnets) {
-		err = &SplitErr{
-			Wrapped:   ErrNoNetSpace,
-			Nets:      nets,
-			Remaining: remaining,
+	// We can now VLSM.
+	vlsm = &VLSMSplitter{
+		// Ascenting and Explicit are pointless to set as all defined sizes are the same.
+		Ascending:     false,
+		Explicit:      false,
+		PrefixLengths: make([]uint8, s.NumberSubnets),
+		BaseSplitter:  s.BaseSplitter,
 	}
+	for i := 0; i < int(s.NumberSubnets); i++ {
+		vlsm.PrefixLengths[i] = uint8(pfxLen)
+	}
+
+	if nets, remaining, err = vlsm.Split(); err != nil {
+		return
+	}
+
+	if s.Strict && remaining != nil && remaining.Prefixes() != nil && len(remaining.Prefixes()) > 0 {
+		err = ErrBadNumNets
 		return
 	}