feat: Handle NAT64 address query

We can query the NAT64 address by the IPv4 address part of the NAT64
address. This is useful when we want to know the NAT64 address of a
specific IPv4 address. We also add a new regex pattern to match the
NAT64 address like 64:ff9b::1.1.1.1 .

Signed-off-by: Yangyu Chen <[email protected]>

Author: cyyself

internal/db/db.go

@@ -2,6 +2,7 @@ package db
 
 import (
 	"log"
+	"net"
 
 	"github.com/spf13/viper"
 
@@ -72,6 +73,19 @@ func Find(typ dbif.QueryType, query string) *Result {
 	if result, found := queryCache.Load(query); found {
 		return result.(*Result)
 	}
+	// Convert NAT64 64:ff9b::/96 to IPv4
+	if typ == dbif.TypeIPv6 {
+		ip := net.ParseIP(query)
+		if ip != nil {
+			_, NAT64, _ := net.ParseCIDR("64:ff9b::/96")
+			if NAT64.Contains(ip) {
+				ip4 := make(net.IP, 4)
+				copy(ip4, ip[12:16])
+				query = ip4.String()
+				typ = dbif.TypeIPv4
+			}
+		}
+	}
 	db := GetDB(typ)
 	result, err := db.Find(query)
 	if err != nil {

pkg/re/re.go

@@ -9,7 +9,7 @@ var (
 	DomainRe = regexp.MustCompile(`([a-zA-Z0-9][-a-zA-Z0-9]{0,62}\.)+([a-zA-Z][-a-zA-Z]{0,62})`)
 
 	IPv4Re = regexp.MustCompile(`(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}`)
-	IPv6Re = regexp.MustCompile(`fe80:(:[0-9a-fA-F]{1,4}){0,4}(%\w+)?|([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}|::[fF]{4}:(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}|(([0-9a-fA-F]{1,4}:){0,6}[0-9a-fA-F]{1,4})?::(([0-9a-fA-F]{1,4}:){0,6}[0-9a-fA-F]{1,4})?`)
+	IPv6Re = regexp.MustCompile(`fe80:(:[0-9a-fA-F]{1,4}){0,4}(%\w+)?|([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}|64:ff9b::(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}|::[fF]{4}:(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}|(([0-9a-fA-F]{1,4}:){0,6}[0-9a-fA-F]{1,4})?::(([0-9a-fA-F]{1,4}:){0,6}[0-9a-fA-F]{1,4})?`)
 )
 
 func MaybeRegexp(s string) bool {