103 lines
2 KiB
Go
103 lines
2 KiB
Go
package radix
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import (
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"net"
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"io"
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"github.com/hashicorp/go-immutable-radix"
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"bufio"
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"bytes"
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"encoding/csv"
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"encoding/binary"
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"strconv"
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"os"
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"fmt"
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)
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// Converts an IP into a byte slice whose elements are the individual bytes of the IP address in big endian format
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// This function assumes that the IPv4 bits are in the LSB of the net.IP. This is an assumption because this is
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// undocumented at the time of writing.
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func getIPBitsInBytes(ip net.IP) []byte {
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var input, ret []byte
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input = ip.To4()
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if input == nil {
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input = ip
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}
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ptr := 0
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for ptr < len(input) {
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intRepr := binary.BigEndian.Uint32(input[ptr:ptr+4])
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var i uint32 = 1 << 31
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var val byte
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for i > 0 {
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if intRepr & i != 0 {
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val = 1
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} else {
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val = 0
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}
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ret = append(ret, val)
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i >>= 1
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}
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ptr += 4
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}
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return ret
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}
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func buildRadixTree(rd io.Reader) (*iradix.Tree, error) {
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t := iradix.New()
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txn := t.Txn()
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scanner := bufio.NewScanner(rd)
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for scanner.Scan() {
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buf := new(bytes.Buffer)
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buf.WriteString(scanner.Text())
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csvrd := csv.NewReader(buf)
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csvrd.Comma = ' '
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csvrd.FieldsPerRecord = 2
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rec, err := csvrd.Read()
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if err != nil {
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return nil, err
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}
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asn, err := strconv.Atoi(rec[0])
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if err != nil {
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return nil, err
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}
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_, prefix, err := net.ParseCIDR(rec[1])
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if err != nil {
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return nil, err
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}
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prefixLen, _ := prefix.Mask.Size()
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ipBstr := getIPBitsInBytes(prefix.IP)
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txn.Insert(ipBstr[:prefixLen], asn)
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}
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if err := scanner.Err() ; err != nil {
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return nil, err
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}
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return txn.Commit(), nil
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}
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func GetASNTree(fn string) (*iradix.Tree, error) {
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var fd *os.File
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var err error
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if fd, err = os.Open(fn) ; err != nil {
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return nil, err
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}
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defer fd.Close()
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return buildRadixTree(fd)
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}
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func GetASNFor(t *iradix.Tree, ip net.IP) (int, error) {
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if t == nil {
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return 0, fmt.Errorf("tree is uninitialized")
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}
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var val interface{}
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var ok bool
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ipBstr := getIPBitsInBytes(ip)
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if _, val, ok = t.Root().LongestPrefix(ipBstr) ; !ok {
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return 0, fmt.Errorf("Cannot find ASN for %s", ip.String())
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}
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asn := val.(int)
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return asn, nil
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}
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