98 lines
1.9 KiB
Go
98 lines
1.9 KiB
Go
package asnutil
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import (
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"errors"
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"fmt"
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"net"
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"github.com/libp2p/go-cidranger"
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)
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var Store *indirectAsnStore
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func init() {
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Store = newIndirectAsnStore()
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}
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type networkWithAsn struct {
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nn net.IPNet
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asn string
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}
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func (e *networkWithAsn) Network() net.IPNet {
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return e.nn
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}
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type asnStore struct {
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cr cidranger.Ranger
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}
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// AsnForIPv6 returns the AS number for the given IPv6 address.
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// If no mapping exists for the given IP, this function will
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// return an empty ASN and a nil error.
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func (a *asnStore) AsnForIPv6(ip net.IP) (string, error) {
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if ip.To16() == nil {
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return "", errors.New("ONLY IPv6 addresses supported for now")
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}
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ns, err := a.cr.ContainingNetworks(ip)
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if err != nil {
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return "", fmt.Errorf("failed to find matching networks for the given ip: %w", err)
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}
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if len(ns) == 0 {
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return "", nil
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}
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// longest prefix match
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n := ns[len(ns)-1].(*networkWithAsn)
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return n.asn, nil
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}
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func newAsnStore() (*asnStore, error) {
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cr := cidranger.NewPCTrieRanger()
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for _, v := range ipv6CidrToAsnPairList {
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_, nn, err := net.ParseCIDR(v.cidr)
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if err != nil {
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return nil, fmt.Errorf("failed to parse CIDR %s: %w", v.cidr, err)
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}
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if err := cr.Insert(&networkWithAsn{*nn, v.asn}); err != nil {
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return nil, fmt.Errorf("failed to insert CIDR %s in Trie store: %w", v.cidr, err)
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}
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}
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return &asnStore{cr}, nil
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}
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type indirectAsnStore struct {
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store *asnStore
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doneLoading chan struct{}
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}
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// AsnForIPv6 returns the AS number for the given IPv6 address.
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// If no mapping exists for the given IP, this function will
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// return an empty ASN and a nil error.
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func (a *indirectAsnStore) AsnForIPv6(ip net.IP) (string, error) {
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<-a.doneLoading
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return a.store.AsnForIPv6(ip)
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}
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func newIndirectAsnStore() *indirectAsnStore {
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a := &indirectAsnStore{
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doneLoading: make(chan struct{}),
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}
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go func() {
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defer close(a.doneLoading)
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store, err := newAsnStore()
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if err != nil {
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panic(err)
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}
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a.store = store
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}()
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return a
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}
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