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!)
110 lines
2.4 KiB
Go
110 lines
2.4 KiB
Go
package netsplit
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import (
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"net/netip"
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`sort`
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"go4.org/netipx"
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)
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/*
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Split splits the network defined in a VLSMSplitter alongside its configuration and performs the subnetting.
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This strategy allows for multiple subnets of differing sizes to be specified.
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remaining may or may not be nil depending on if all desired subnet sizes fit cleanly into the network boundaries.
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*/
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func (v *VLSMSplitter) Split() (nets []*netip.Prefix, remaining *netipx.IPSet, err error) {
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var ok bool
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var pfxLen int
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var pfxLen8 uint8
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var base netip.Prefix
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var sub netip.Prefix
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var subPtr *netip.Prefix
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var ipsb *netipx.IPSetBuilder = new(netipx.IPSetBuilder)
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if v == nil || v.PrefixLengths == nil || len(v.PrefixLengths) == 0 || v.BaseSplitter == nil || v.network == nil {
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return
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}
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if err = validate.Struct(v); err != nil {
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return
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}
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if err = ValidateSizes(v.network, v.PrefixLengths...); err != nil {
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return
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}
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/*
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I thought about using the following:
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* https://pkg.go.dev/net/netip
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* https://pkg.go.dev/github.com/sacloud/packages-go/cidr
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* https://pkg.go.dev/github.com/projectdiscovery/mapcidr
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* https://pkg.go.dev/github.com/EvilSuperstars/go-cidrman
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But, as I expected, netipx ftw again.
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*/
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if !v.Explicit {
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sort.SliceStable(
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v.PrefixLengths,
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func(i, j int) (isBefore bool) { // We use a reverse sorting by default so we get larger prefixes at the beginning.
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if v.Ascending {
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isBefore = v.PrefixLengths[i] > v.PrefixLengths[j]
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} else {
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isBefore = v.PrefixLengths[i] < v.PrefixLengths[j]
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}
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return
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},
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)
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}
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pfxLen, _ = v.network.Mask.Size()
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pfxLen8 = uint8(pfxLen)
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if base, ok = netipx.FromStdIPNet(v.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.AddPrefix(base)
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if remaining, err = ipsb.IPSet(); err != nil {
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return
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}
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for _, size := range v.PrefixLengths {
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if size < pfxLen8 {
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err = &SplitErr{
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Wrapped: ErrBigPrefix,
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Nets: nets,
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Remaining: remaining,
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LastSubnet: &sub,
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RequestedPrefixLen: size,
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}
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return
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}
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if sub, remaining, ok = remaining.RemoveFreePrefix(size); !ok {
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err = &SplitErr{
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Wrapped: ErrNoNetSpace,
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Nets: nets,
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Remaining: remaining,
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LastSubnet: &sub,
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RequestedPrefixLen: size,
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}
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return
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}
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subPtr = new(netip.Prefix)
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*subPtr = sub
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nets = append(nets, subPtr)
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}
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return
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}
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