policy: allow fetching ASN directly via RADb WHOIS service

utils/radb.go

@@ -0,0 +1,167 @@
+package utils
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"net"
+	"regexp"
+	"strings"
+	"time"
+)
+
+type RADb struct {
+	target string
+	dialer net.Dialer
+}
+
+const RADBServer = "whois.radb.net:43"
+
+func NewRADb() (*RADb, error) {
+
+	host, port, err := net.SplitHostPort(RADBServer)
+	if err != nil {
+		return nil, err
+	}
+
+	return &RADb{
+		target: fmt.Sprintf("%s:%s", host, port),
+		dialer: net.Dialer{
+			Timeout: 5 * time.Second,
+		},
+	}, nil
+}
+
+var whoisRouteRegex = regexp.MustCompile("(?P<prefix>(([0-9]+\\.[0-9]+\\.[0-9]+\\.[0-9]+)|([0-9a-f:]+::))/[0-9]+)")
+
+func (db *RADb) query(fn func(n int, record []byte) error, queries ...string) error {
+
+	conn, err := db.dialer.Dial("tcp", db.target)
+	if err != nil {
+		return err
+	}
+	defer conn.Close()
+
+	if len(queries) > 1 {
+		// enable persistent conn
+		_ = conn.SetDeadline(time.Now().Add(time.Second * 5))
+		_, err = conn.Write([]byte("!!\n"))
+		if err != nil {
+			return err
+		}
+	}
+
+	scanner := bufio.NewScanner(conn)
+	scanner.Split(bufio.ScanLines)
+
+	for _, q := range queries {
+
+		_ = conn.SetDeadline(time.Now().Add(time.Second * 5))
+		_, err = conn.Write([]byte(strings.TrimSpace(q) + "\n"))
+		if err != nil {
+			return err
+		}
+
+		n := 0
+
+		for scanner.Scan() {
+			buf := bytes.Trim(scanner.Bytes(), "\r\n")
+			if bytes.HasPrefix(buf, []byte("%")) || bytes.Equal(buf, []byte("C")) {
+				// end of record
+				break
+			}
+			err = fn(n, buf)
+			if err != nil {
+				return err
+			}
+			n++
+		}
+	}
+
+	if len(queries) > 1 {
+		// exit
+		_ = conn.SetDeadline(time.Now().Add(time.Second * 5))
+		_, err = conn.Write([]byte("q\n"))
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func init() {
+	db, _ := NewRADb()
+	db.FetchIPInfo(net.ParseIP("162.158.62.1"))
+}
+
+func (db *RADb) FetchIPInfo(ip net.IP) (result []string, err error) {
+	var ipNet net.IPNet
+	if ip4 := ip.To4(); ip4 != nil {
+		ipNet = net.IPNet{
+			IP: ip4,
+			// single ip
+			Mask: net.CIDRMask(len(ip4)*8, len(ip4)*8),
+		}
+	} else {
+		ipNet = net.IPNet{
+			IP: ip,
+			// single ip
+			Mask: net.CIDRMask(len(ip)*8, len(ip)*8),
+		}
+	}
+
+	err = db.query(func(n int, record []byte) error {
+		result = append(result, string(record))
+		return nil
+	}, fmt.Sprintf("!r%s,l", ipNet.String()))
+
+	if err != nil {
+		return nil, err
+	}
+
+	return result, nil
+}
+
+func (db *RADb) FetchASNets(asn int) (result []net.IPNet, err error) {
+
+	ix := whoisRouteRegex.SubexpIndex("prefix")
+	if ix == -1 {
+		panic("invalid regex prefix")
+	}
+
+	var data []byte
+
+	err = db.query(func(n int, record []byte) error {
+		if n == 0 {
+			// do not append ASN number reply
+			return nil
+		}
+		// pad data
+		if n == 1 {
+			data = append(data, ' ')
+		}
+		data = append(data, record...)
+		return nil
+	},
+		// See https://www.radb.net/query/help
+		// fetch IPv4 routes
+		fmt.Sprintf("!gas%d", asn),
+		// fetch IPv6 routes
+		fmt.Sprintf("!6as%d", asn),
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	matches := whoisRouteRegex.FindAllSubmatch(data, -1)
+	for _, match := range matches {
+		_, ipNet, err := net.ParseCIDR(string(match[ix]))
+		if err != nil {
+			return nil, fmt.Errorf("invalid CIDR %s: %w", string(match[ix]), err)
+		}
+		result = append(result, *ipNet)
+	}
+
+	return result, nil
+}