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!)
72 lines
1.7 KiB
Go
72 lines
1.7 KiB
Go
package netsplit
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import (
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"net/netip"
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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 CIDRSplitter alongside its configuration and performs the subnetting.
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This strategy attempts to split a network into subnets of a single uniform explicit size.
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*/
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func (c *CIDRSplitter) 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 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 c == nil || c.PrefixLength == 0 || c.BaseSplitter == nil || c.network == nil {
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return
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}
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if err = validate.Struct(c); err != nil {
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return
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}
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if base, ok = netipx.FromStdIPNet(c.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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if c.PrefixLength < uint8(base.Bits()) {
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err = ErrBigPrefix
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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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/*
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TODO: This is *super* slow for tiny subnets in a large net.
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For future optimzation, first off benchmark to make sure it makes a difference, but
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chunk out the network (how to find appropriate length?) of n < x < y, where n is the network pfx len,
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and goroutine each split into a channel.
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Because this splits *on CIDR boundaries* and we aren't VLSM-ing, remaining never has to be considered-
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it'll always be clean splitting.
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See CIDRSplitter.LenSwitch.
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*/
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for {
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if sub, remaining, ok = remaining.RemoveFreePrefix(c.PrefixLength); !ok {
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if !sub.IsValid() {
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// No error; it's literally impossible since we network on boundaries.
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// We just hit the end of the prefix.
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break
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}
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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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