mirror of https://github.com/containers/podman.git
79 lines
1.7 KiB
Go
79 lines
1.7 KiB
Go
package network
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/*
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The code in this was kindly contributed by Dan Williams(dcbw@redhat.com). Many thanks
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for his contributions.
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*/
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import (
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"fmt"
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"net"
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)
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func incByte(subnet *net.IPNet, idx int, shift uint) error {
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if idx < 0 {
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return fmt.Errorf("no more subnets left")
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}
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if subnet.IP[idx] == 255 {
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subnet.IP[idx] = 0
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return incByte(subnet, idx-1, 0)
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}
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subnet.IP[idx] += 1 << shift
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return nil
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}
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// NextSubnet returns subnet incremented by 1
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func NextSubnet(subnet *net.IPNet) (*net.IPNet, error) {
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newSubnet := &net.IPNet{
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IP: subnet.IP,
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Mask: subnet.Mask,
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}
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ones, bits := newSubnet.Mask.Size()
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if ones == 0 {
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return nil, fmt.Errorf("%s has only one subnet", subnet.String())
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}
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zeroes := uint(bits - ones)
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shift := zeroes % 8
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idx := ones/8 - 1
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if idx < 0 {
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idx = 0
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}
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if err := incByte(newSubnet, idx, shift); err != nil {
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return nil, err
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}
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return newSubnet, nil
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}
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// LastIPInSubnet gets the last IP in a subnet
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func LastIPInSubnet(addr *net.IPNet) (net.IP, error) { //nolint:interfacer
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// re-parse to ensure clean network address
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_, cidr, err := net.ParseCIDR(addr.String())
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if err != nil {
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return nil, err
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}
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ones, bits := cidr.Mask.Size()
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if ones == bits {
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return FirstIPInSubnet(cidr)
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}
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hostStart := ones / 8
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// Handle the first host byte
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cidr.IP[hostStart] |= 0xff & cidr.Mask[hostStart]
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// Fill the rest with ones
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for i := hostStart; i < len(cidr.IP); i++ {
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cidr.IP[i] = 0xff
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}
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return cidr.IP, nil
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}
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// FirstIPInSubnet gets the first IP in a subnet
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func FirstIPInSubnet(addr *net.IPNet) (net.IP, error) { //nolint:interfacer
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// re-parse to ensure clean network address
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_, cidr, err := net.ParseCIDR(addr.String())
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if err != nil {
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return nil, err
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}
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cidr.IP[len(cidr.IP)-1]++
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return cidr.IP, nil
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}
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