860ad5842b
ADDED: * num-addrs subcommand, to get the number of hosts/addresses in a given prefix length * get-net subcommand, to more easily get a single subnet from either the beginning or the end of a prefix. (MUCH FASTER than CIDR-splitting!)
103 lines
2.3 KiB
Go
103 lines
2.3 KiB
Go
package netsplit
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import (
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`fmt`
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`net/netip`
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`go4.org/netipx`
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)
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// Split is to conform to a NetSplitter, though a PrefixGetter is *technically* not a splitter.
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func (p *PrefixGetter) Split() (nets []*netip.Prefix, remaining *netipx.IPSet, err error) {
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var ok bool
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var base netip.Prefix
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var vlsmS *VLSMSplitter
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var addr netip.Addr
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var maxPfxLen uint8 = maxBitsv4
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var ipsb *netipx.IPSetBuilder = new(netipx.IPSetBuilder)
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if p == nil || p.PrefixLength == 0 || p.BaseSplitter == nil || p.network == nil {
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return
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}
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if err = validate.Struct(p); err != nil {
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return
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}
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// If the position is "first", we can simply call a VLSM.
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if p.Pos == "first" {
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vlsmS = &VLSMSplitter{
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Ascending: false,
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Explicit: false,
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PrefixLengths: []uint8{p.PrefixLength},
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BaseSplitter: p.BaseSplitter,
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}
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if nets, remaining, err = vlsmS.Split(); err != nil {
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return
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}
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return
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}
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if p.Pos != "last" {
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err = ErrUnknownPos
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return
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}
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// Otherwise this gets... messy.
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if base, ok = netipx.FromStdIPNet(p.network); !ok {
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err = ErrBadBoundary
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return
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}
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if !base.IsValid() {
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err = ErrBadBoundary
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return
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}
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ipsb = new(netipx.IPSetBuilder)
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ipsb.AddPrefix(base.Masked())
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// First if it's a single host prefix, ezpz gg no re.
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if base.Addr().Is6() {
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maxPfxLen = maxBitsv6
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}
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if p.PrefixLength == maxPfxLen {
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nets = make([]*netip.Prefix, 1)
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nets[0] = new(netip.Prefix)
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addr = netipx.PrefixLastIP(base)
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fmt.Println(addr.String())
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if *nets[0], err = addr.Prefix(int(p.PrefixLength)); err != nil {
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return
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}
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ipsb.Remove(addr)
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if remaining, err = ipsb.IPSet(); err != nil {
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return
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}
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return
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}
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// Otherwise this gets... interesting.
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/*
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For IPv4, performance NORMALLY would be "fine" on modern hardware with:
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1. straight CIDR-splitting
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2. grabbing the last prefix
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3. condensing the leading prefixes to a new IPSet
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But even this can take a long time (see CIDRSplitter.Split comments).
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In almost all cases (unless subnetting like, n+12 prefix length),
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IPv6 takes WAY too long.
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So use the same function (LastSubnetPfx) for both cases.
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*/
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nets = make([]*netip.Prefix, 1)
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nets[0] = new(netip.Prefix)
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if *nets[0], err = LastSubnetPfx(base, p.PrefixLength); err != nil {
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return
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}
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ipsb.RemovePrefix(*nets[0])
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if remaining, err = ipsb.IPSet(); err != nil {
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return
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}
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return
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}
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