v0.2.1

FIXED: * host splitter wasn't working quite correctly; this has been fixed.
2025-04-06 18:26:18 -04:00
parent fd344f3b8e
commit 3c1bc832c0
7 changed files with 221 additions and 90 deletions
--- a/netsplit/funcs.go
+++ b/netsplit/funcs.go
@@ -193,25 +193,26 @@ func CheckReserved(nets []*netip.Prefix, revRecursive, recursive, excludePrivate
 				reservations = make(map[netip.Prefix]*IANAAddrNetResRecord)
 			}
 			reservations[*n] = res
-			if !revRecursive && !recursive {
-				continue
-			}
-			for p, r := range reserved {
-				// This... *should* be safe? I don't think any reservations overlap.
-				// Anyways, revRecursive works because n.Addr() returns the network address, which should be the canonical boundary.
-				// recursive works for the same reason, just the other end.
-				// Math!
-				if revRecursive && p.Contains(n.Addr()) {
-					if reservations == nil {
-						reservations = make(map[netip.Prefix]*IANAAddrNetResRecord)
-					}
-					reservations[p] = r
-				} else if recursive && n.Contains(p.Addr()) {
-					if reservations == nil {
-						reservations = make(map[netip.Prefix]*IANAAddrNetResRecord)
-					}
-					reservations[p] = r
+		}
+		if !revRecursive && !recursive {
+			continue
+		}
+		for p, r := range reserved {
+			// This... *should* be safe? I don't think any reservations overlap.
+			// Anyways, revRecursive works because n.Addr() returns the network address, which should be the canonical boundary.
+			// recursive works for the same reason, just the other end.
+			// Math!
+			if revRecursive && p.Contains(n.Addr()) {
+				if reservations == nil {
+					reservations = make(map[netip.Prefix]*IANAAddrNetResRecord)
 				}
+				reservations[p] = r
+			}
+			if recursive && n.Bits() < p.Bits() && n.Contains(p.Addr()) {
+				if reservations == nil {
+					reservations = make(map[netip.Prefix]*IANAAddrNetResRecord)
+				}
+				reservations[p] = r
 			}
 		}
 	}
@@ -223,7 +224,7 @@ func CheckReserved(nets []*netip.Prefix, revRecursive, recursive, excludePrivate
 func Contain(origPfx *netip.Prefix, nets []*netip.Prefix, remaining *netipx.IPSet, splitter NetSplitter) (s *StructuredResults, err error) {

 	var rem []netip.Prefix
-	var reserved map[netip.Prefix]*IANAAddrNetResRecord
+	// var reserved map[netip.Prefix]*IANAAddrNetResRecord
 	var sr = StructuredResults{
 		Original: origPfx,
 	}
@@ -276,19 +277,21 @@ func Contain(origPfx *netip.Prefix, nets []*netip.Prefix, remaining *netipx.IPSe
 		}
 	}

-	if nets != nil {
-		if reserved, err = CheckReserved(nets, true, true, false); err != nil {
-			return
-		}
-		if reserved != nil && len(reserved) > 0 {
-			s.Reservations = make([]*IANAAddrNetResRecord, len(reserved))
-			idx := 0
-			for _, r := range reserved {
-				s.Reservations[idx] = r
-				idx++
+	/*
+		if nets != nil {
+			if reserved, err = CheckReserved(nets, true, true, false); err != nil {
+				return
+			}
+			if reserved != nil && len(reserved) > 0 {
+				s.Reservations = make([]*IANAAddrNetResRecord, len(reserved))
+				idx := 0
+				for _, r := range reserved {
+					s.Reservations[idx] = r
+					idx++
+				}
 			}
 		}
-	}
+	*/

 	s = &sr

@@ -377,27 +380,105 @@ func MaskInvert(mask net.IPMask) (inverted net.IPMask) {
 	return
 }

+/*
+	NumAddrsIn returns the number of addresses in a given prefix length
+	and inet family.
+
+	If isIpv6 is false, it is assumed to be IPv4 (...duh).
+
+	inclNet and inclBcast have the same meanings as in NumAddrsNet and NumAddrsPfx.
+
+	Note that for the single-host prefix (/32 for IPv4, /128 for IPv6), numAddrs will *always* be 1.
+	For point-to-point prefix (IPv4 /31, IPv6 /127), numAddrs will *ALWAYS* be 2.
+*/
+func NumAddrsIn(prefixLen uint8, isIpv6, inclNet, inclBcast bool) (numAddrs *big.Int, err error) {
+
+	var numBits uint
+	var numRemoved int64
+	var maxBitLen uint8 = maxBitsv4
+
+	if isIpv6 {
+		maxBitLen = maxBitsv6
+	}
+	if prefixLen > maxBitLen {
+		err = ErrBadPrefixLen
+		return
+	}
+	if prefixLen == maxBitLen {
+		numAddrs = big.NewInt(1)
+		return
+	}
+	if (prefixLen + 1) == maxBitLen {
+		numAddrs = big.NewInt(2)
+		return
+	}
+
+	numBits = uint(maxBitLen - prefixLen)
+
+	numAddrs = new(big.Int).Lsh(big.NewInt(1), numBits)
+
+	if !inclNet {
+		numRemoved++
+	}
+	if !inclBcast {
+		numRemoved++
+	}
+	if numRemoved > 0 {
+		_ = numAddrs.Sub(numAddrs, big.NewInt(numRemoved))
+	}
+
+	return
+}
+
 /*
 NumAddrsNet returns the number of IP addresses in a net.IPNet.

-# The network address is included in the count if inclNet is true, otherwise it is excluded
+The network address is included in the count if inclNet is true, otherwise it is excluded.

-Only assignable addresses ("hosts") are considered if hostsOnly is true,
-otherwise all addresses are counted (depending on inclNet).
+The broadcast (or reserved broadcast, in the case of IPv6) address will be included in
+the count if inclBcast is true, otherwise it is excluded.
+
+numAddrs will be nil if pfx is nil or invalid.
 */
-func NumAddrsNet(pfx *net.IPNet, inclNet, hostsOnly bool) (numAddrs *big.Int) {
+func NumAddrsNet(pfx *net.IPNet, inclNet, inclBcast bool) (numAddrs *big.Int) {
+
+	var nPfx netip.Prefix
+	var ok bool

 	if pfx == nil {
 		return
 	}
+	if nPfx, ok = netipx.FromStdIPNet(pfx); !ok {
+		return
+	}

-	// TODO
+	numAddrs = NumAddrsPfx(nPfx, inclNet, inclBcast)

 	return
 }

 // NumAddrsPfx is the exact same as NumAddrsNet but for a net/netip.Prefix instead.
-// TODO
+func NumAddrsPfx(pfx netip.Prefix, inclNet, inclBcast bool) (numAddrs *big.Int) {
+
+	var numBits uint
+	var numRemoved int64
+
+	numBits = uint(pfx.Addr().BitLen() - pfx.Bits())
+
+	numAddrs = new(big.Int).Lsh(big.NewInt(1), numBits)
+
+	if !inclNet {
+		numRemoved++
+	}
+	if !inclBcast {
+		numRemoved++
+	}
+	if numRemoved > 0 {
+		_ = numAddrs.Sub(numAddrs, big.NewInt(numRemoved))
+	}
+
+	return
+}

 /*
 NumNets returns the number of times prefix size subnet fits into prefix size network.
--- a/netsplit/funcs_hostsplitter.go
+++ b/netsplit/funcs_hostsplitter.go
@@ -1,12 +1,9 @@
 package netsplit

 import (
-	"fmt"
 	"math/big"
-	"net"
 	"net/netip"

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

@@ -16,54 +13,84 @@ This strategy attempts to split the network into subnets of equal number of host

 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.
+An ErrBadNumHosts will be returned if the number of hosts does not match the *exact* number of addresses per spec in a prefix.
 */
 func (h *HostSplitter) Split() (nets []*netip.Prefix, remaining *netipx.IPSet, err error) {

+	var pfx netip.Prefix
 	var tgt *big.Int
+	var splitCidr int
 	var hosts *big.Int
-	var sub netip.Prefix
-	var subPtr *netip.Prefix
-	var split []*net.IPNet
-	var ipsb *netipx.IPSetBuilder = new(netipx.IPSetBuilder)
+	var found bool
+	var cs *CIDRSplitter

 	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 {
+	pfx, _ = netipx.FromStdIPNet(h.network)
+	tgt = new(big.Int)
+	tgt.SetUint64(uint64(h.NumberHosts))
+
+	if NumAddrsPfx(pfx, h.InclNetAddr, h.InclBcastAddr).Cmp(tgt) < 0 {
+		// The number of hosts per-subnet exceeds the number of addresses in the specified network.
+		err = ErrNoNetSpace
+		return
+	}
+	/*
+		Iterate up through prefix lengths for the inet family's maximum length, getting larger and larger,
+		until we reach the first prefix that can contain tgt.
+		If we reach h.network.Bits(), we are forced to use that.
+		(Any case otherwise should be handled by the above checks.)
+	*/
+	for splitCidr = pfx.Addr().BitLen(); splitCidr >= pfx.Bits(); splitCidr-- {
+		if hosts, err = NumAddrsIn(uint8(splitCidr), pfx.Addr().Is6(), h.InclNetAddr, h.InclBcastAddr); err != nil {
+			return
+		}
+		if hosts.Cmp(tgt) >= 0 {
+			found = true
+			break
+		}
+	}
+	if !found {
+		// Pragmatically, we should never be able to get to this code.
+		err = ErrNoNetSpace
 		return
 	}

-	fmt.Println(split)
-
-	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)
+	// Now that we have an appropriate prefix length for splitting, we can offload a huge portion of that to a CIDRSplitter.
+	cs = &CIDRSplitter{
+		PrefixLength: uint8(splitCidr),
+		BaseSplitter: h.BaseSplitter,
+	}
+	if nets, remaining, err = cs.Split(); err != nil {
+		return
+	}
+	// If strict mode is enabled, we then need to match the number of hosts exactly in the subnet.
+	if !h.Strict {
+		return
+	}
+	// First off, if remaining is not nil/empty, that immediately fails strict.
+	if remaining != nil && remaining.Prefixes() != nil && len(remaining.Prefixes()) != 0 {
+		err = &SplitErr{
+			Wrapped:            ErrBadNumHosts,
+			Nets:               nets,
+			Remaining:          remaining,
+			LastSubnet:         nil,
+			RequestedPrefixLen: uint8(splitCidr),
 		}
-
-		nets[idx] = new(netip.Prefix)
-		*nets[idx] = sub
+		return
 	}

-	if remaining, err = ipsb.IPSet(); err != nil {
+	// Then we check the cidr we split on, and check its number of hosts.
+	if hosts.Cmp(tgt) != 0 {
+		err = &SplitErr{
+			Wrapped:            ErrBadNumHosts,
+			Nets:               nets,
+			Remaining:          remaining,
+			LastSubnet:         nil,
+			RequestedPrefixLen: uint8(splitCidr),
+		}
 		return
 	}

--- a/netsplit/types.go
+++ b/netsplit/types.go
@@ -51,6 +51,10 @@ 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"`
+	// InclNetAddr, if true, specifies that NumberHosts includes the network address.
+	InclNetAddr bool `json:"net_addr" xml:"netAddr,attr,omitempty" yaml:"Network Address Included,omitempty"`
+	// InclBcastAddr, if true, specifies that NumberHosts includes the broadcast address.
+	InclBcastAddr bool `json:"bcast_addr" xml:"bcast,attr,omitempty" yaml:"Broadcast Address Included,omitempty"`
 	// 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"`
@@ -78,14 +82,14 @@ type VLSMSplitter struct {
 		(ascending order) instead of larger networks/smaller prefixes (descending order).
 		You almost assuredly do not want to do this.
 	*/
-	Ascending bool
+	Ascending bool `json:"asc,omitempty" xml:"asc,attr,omitempty" yaml:"Ascending Order,omitempty"`
 	/*
 		Explicit, if true, will ignore Ascending completely and split in the explicit order of PrefixLengths.

 		This has the potential to be *extremely* wasteful of addressing space as the resulting blocks are
 		VERY unoptimized.
 	*/
-	Explicit bool
+	Explicit bool `json:"explicit,omitempty" xml:"explicit,attr,omitempty" yaml:"Explicit Ordering,omitempty"`
 	// PrefixLengths contains the prefix lengths of each subnet to split out from the network.
 	PrefixLengths []uint8 `json:"prefixes" xml:"prefixes>prefix" yaml:"Prefix Lengths"`
 	*BaseSplitter `json:"net" xml:"net,omitempty" yaml:"network,omitempty"`