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fix nat64 well-known prefix check (#205)
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* fix nat64 well-known prefix check

* don't use pointer

* make NAT64WellKnownPrefix private
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sukunrt authored Jul 10, 2023
1 parent e9b02fc commit 0e7485e
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Showing 2 changed files with 17 additions and 6 deletions.
18 changes: 12 additions & 6 deletions net/ip.go
Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
package manet

import (
"bytes"
"net"

ma "github.com/multiformats/go-multiaddr"
Expand Down Expand Up @@ -118,13 +117,20 @@ func zoneless(m ma.Multiaddr) ma.Multiaddr {
}
}

var NAT64WellKnownPrefix = [4]byte{0x0, 0x64, 0xff, 0x9b}
var nat64WellKnownPrefix net.IPNet

// IsNAT64IPv4ConvertedIPv6Addr returns whether addr is an IPv6 address that begins with
// the well-known prefix "64:ff9b" used for NAT64 Translation
// see RFC 6052
func init() {
_, np, err := net.ParseCIDR("64:ff9b::/96")
if err != nil {
panic(err)
}
nat64WellKnownPrefix = *np
}

// IsNAT64IPv4ConvertedIPv6Addr returns whether addr is a well-known prefix "64:ff9b::/96" addr
// used for NAT64 Translation. See RFC 6052
func IsNAT64IPv4ConvertedIPv6Addr(addr ma.Multiaddr) bool {
c, _ := ma.SplitFirst(addr)
return c != nil && c.Protocol().Code == ma.P_IP6 &&
bytes.HasPrefix(c.RawValue(), NAT64WellKnownPrefix[:])
nat64WellKnownPrefix.Contains(net.IP(c.RawValue()))
}
5 changes: 5 additions & 0 deletions net/ip_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,11 @@ func TestIsWellKnownPrefixIPv4ConvertedIPv6Address(t *testing.T) {
want: true,
failureReason: "ip6 address begins with well-known prefix",
},
{
addr: ma.StringCast("/ip6/64:ff9b::1:192.0.1.2/tcp/1234"),
want: false,
failureReason: "64:ff9b::1 is not well-known prefix",
},
}
for i, tc := range cases {
t.Run(fmt.Sprintf("%d", i), func(t *testing.T) {
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