94 lines
2.4 KiB
Go
94 lines
2.4 KiB
Go
package asnutil
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import (
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_ "embed"
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"encoding/binary"
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"errors"
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"math"
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"net"
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"strconv"
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)
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//go:embed sorted-network-list.bin
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var dataset string
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const entrySize = 8*2 + 4 // start, end 8 bytes; asn 4 bytes
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func readEntry(index uint) (start, end uint64, asn uint32) {
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base := entrySize * index
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b := dataset[base : base+entrySize]
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start = uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 | uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
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b = b[8:]
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end = uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 | uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
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b = b[8:]
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asn = uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
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return
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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 network, this function will return a zero ASN number.
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func AsnForIPv6(ip net.IP) (asn uint32) {
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ip = ip.To16()
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if ip == nil {
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return
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}
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return AsnForIPv6Network(binary.BigEndian.Uint64(ip))
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}
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func init() {
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if len(dataset) > math.MaxUint/2 {
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panic("list is too big and would overflow in binary search")
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}
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}
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// AsnForIPv6Network returns the AS number for the given IPv6 network.
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// If no mapping exists for the given network, this function will return a zero ASN number.
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// network is the first 64 bits of the ip address interpreted as big endian.
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func AsnForIPv6Network(network uint64) (asn uint32) {
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n := uint(len(dataset)) / entrySize
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var i, j uint = 0, n
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for i < j {
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h := (i + j) / 2 // wont overflow since the list can't be that large
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start, end, asn := readEntry(h)
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if start <= network {
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if network <= end {
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return asn
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}
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i = h + 1
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} else {
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j = h
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}
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}
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if i >= n {
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return 0
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}
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start, end, asn := readEntry(i)
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if start <= network && network <= end {
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return asn
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}
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return 0
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}
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// Deprecated: use [AsnForIPv6] or [AsnForIPv6Network], they do not allocate.
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var Store backwardCompat
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type backwardCompat struct{}
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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 (backwardCompat) AsnForIPv6(ip net.IP) (string, error) {
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ip = ip.To16()
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if ip == nil {
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return "", errors.New("ONLY IPv6 addresses supported")
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}
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asn := AsnForIPv6Network(binary.BigEndian.Uint64(ip))
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if asn == 0 {
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return "", nil
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}
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return strconv.FormatUint(uint64(asn), 10), nil
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}
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func (backwardCompat) Init() {}
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