Bryan Boreham
f05225da22
For a network, as used by IPAM, we care if *any* address in the range could possibly conflict with an existing address routed by the host. When given a single address, we only care if *that specific address* conflicts with an existing route.
44 lines
1.2 KiB
Go
44 lines
1.2 KiB
Go
package net
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import (
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"fmt"
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"net"
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"github.com/vishvananda/netlink"
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)
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// A network is considered free if it does not overlap any existing
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// routes on this host. This is the same approach taken by Docker.
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func CheckNetworkFree(subnet *net.IPNet) error {
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routes, err := netlink.RouteList(nil, netlink.FAMILY_V4)
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if err != nil {
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return err
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}
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for _, route := range routes {
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if route.Dst != nil && overlaps(route.Dst, subnet) {
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return fmt.Errorf("Network %s would overlap with existing route %s", subnet, route.Dst)
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}
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}
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return nil
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}
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// Two networks overlap if the start-point of one is inside the other.
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func overlaps(n1, n2 *net.IPNet) bool {
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return n1.Contains(n2.IP) || n2.Contains(n1.IP)
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}
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// For a specific address, we only care if it is actually *inside* an
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// existing route, because weave-local traffic never hits IP routing.
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func CheckAddressOverlap(addr net.IP) error {
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routes, err := netlink.RouteList(nil, netlink.FAMILY_V4)
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if err != nil {
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return err
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}
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for _, route := range routes {
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if route.Dst != nil && route.Dst.Contains(addr) {
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return fmt.Errorf("Address %s would overlap with existing route %s", addr, route.Dst)
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}
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}
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return nil
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}
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