From 9c436306cb6733f601527384bb1d6e39cc13d59f Mon Sep 17 00:00:00 2001
From: Kevin Wallace <doof@doof.net>
Date: Thu, 30 Sep 2021 07:11:14 -0700
Subject: parse origin info, fetch ASN name

---
 main.go | 40 ++++++++++++++++++++++++++++++++++------
 1 file changed, 34 insertions(+), 6 deletions(-)

diff --git a/main.go b/main.go
index 01401d4..f96dab8 100644
--- a/main.go
+++ b/main.go
@@ -5,13 +5,15 @@ import (
 	"fmt"
 	"net"
 	"os"
+	"strconv"
 	"strings"
 )
 
 var (
 	txt = flag.Bool("txt", false, "also look up TXT records")
-	asn = flag.Bool("asn", false, "also look up ASN info from -asn-zone4/-asn-zone6 reverse zones")
+	asn = flag.Bool("asn", false, "also look up ASN info from -asn-zone{,4,6} reverse zones")
 
+	asnZone = flag.String("asn-zone", "asn.cymru.com", "ASN info zone for -asn")
 	asnZone4 = flag.String("asn-zone4", "origin.asn.cymru.com", "v4 reverse zone for -asn")
 	asnZone6 = flag.String("asn-zone6", "origin6.asn.cymru.com", "v6 reverse zone for -asn")
 )
@@ -25,12 +27,22 @@ func main() {
 			fmt.Printf("# %s\n", arg)
 			for _, ipnet := range ipnets {
 				if *asn {
-					asnInfos, err := lookupAsnInfo(ipnet)
+					originInfos, err := lookupOriginInfo(ipnet)
 					if err != nil {
-						printErr(ipnet, "ASN", err)
+						printErr(ipnet, "origin", err)
 					} else {
-						for _, asnInfo := range asnInfos {
-							fmt.Printf("# %s\n", asnInfo)
+						for _, originInfo := range originInfos {
+							parts := strings.SplitN(originInfo, " | ", 2)
+							if asn, err := strconv.Atoi(parts[0]); err == nil {
+								asnNames, err := lookupAsnNames(asn)
+								if err != nil {
+									printErr(asn, "asn", err)
+								} else if len(asnNames) > 0 {
+									parts[0] += " | " + strings.Join(asnNames, "; ")
+								}
+							}
+							originInfo = strings.Join(parts, " | ")
+							fmt.Printf("# %s\n", originInfo)
 						}
 					}
 				}
@@ -161,7 +173,7 @@ func resolveHost(host string, canLookup bool) ([]net.IP, error) {
 	return nil, fmt.Errorf("can't parse IP")
 }
 
-func lookupAsnInfo(ipnet net.IPNet) ([]string, error) {
+func lookupOriginInfo(ipnet net.IPNet) ([]string, error) {
 	ones, bits := ipnet.Mask.Size()
 	if bits == 0 {
 		return nil, fmt.Errorf("invalid netmask in %s", ipnet)
@@ -181,3 +193,19 @@ func lookupAsnInfo(ipnet net.IPNet) ([]string, error) {
 	}
 	return net.LookupTXT(name)
 }
+
+func lookupAsnNames(asn int) ([]string, error) {
+	recs, err := net.LookupTXT(fmt.Sprintf("AS%d.%s", asn, *asnZone))
+	if err != nil {
+		return nil, err
+	}
+	var names []string
+	for _, rec := range recs {
+		parts := strings.Split(rec, " | ")
+		if len(parts) != 5 {
+			return nil, fmt.Errorf("unknown asn info format for %d: %s", asn, rec)
+		}
+		names = append(names, parts[4])
+	}
+	return names, nil
+}
-- 
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