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fix loopback/link-local checks

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1. Ensure we check the entire addr, not just a prefix.
2. Make the LinkLocal test skip zones.
3. Consider link-local multicast to be link-local.
4. Defer to *go* to determine if something is, in fact, a loopback/link-local address.
This commit is contained in:
Steven Allen 2018-10-17 21:42:29 +01:00
parent 3895ff188b
commit 03e871bdbe
2 changed files with 36 additions and 21 deletions
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51
ip.go
View File

@ -1,7 +1,7 @@
package manet
import (
"bytes"
"net"
ma "github.com/multiformats/go-multiaddr"
)
@ -24,14 +24,6 @@ var (
IP6Unspecified = ma.StringCast("/ip6/::")
)
// Loopback multiaddr prefixes. Any multiaddr beginning with one of the
// following byte sequences is considered a loopback multiaddr.
var loopbackPrefixes = [][]byte{
{ma.P_IP4, 127}, // 127.*
{ma.P_IP6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, 127}, // ::ffff:127.*
IP6Loopback.Bytes(), // ::1
}
// IsThinWaist returns whether a Multiaddr starts with "Thin Waist" Protocols.
// This means: /{IP4, IP6}[/{TCP, UDP}]
func IsThinWaist(m ma.Multiaddr) bool {
@ -62,22 +54,41 @@ func IsThinWaist(m ma.Multiaddr) bool {
// IsIPLoopback returns whether a Multiaddr is a "Loopback" IP address
// This means either /ip4/127.*.*.*, /ip6/::1, or /ip6/::ffff:127.*.*.*.*
func IsIPLoopback(m ma.Multiaddr) bool {
b := m.Bytes()
for _, prefix := range loopbackPrefixes {
if bytes.HasPrefix(b, prefix) {
return true
}
c, rest := ma.SplitFirst(m)
if rest != nil {
// Not *just* an IPv4 addr
return false
}
switch c.Protocol().Code {
case ma.P_IP4, ma.P_IP6:
return net.IP(c.RawValue()).IsLoopback()
}
return false
}
// IsIP6LinkLocal returns if a multiaddress is an IPv6 local link. These
// addresses are non routable. The prefix is technically
// fe80::/10, but we test fe80::/16 for simplicity (no need to mask).
// So far, no hardware interfaces exist long enough to use those 2 bits.
// Send a PR if there is.
// IsIP6LinkLocal returns if a an IPv6 link-local multiaddress (with zero or
// more leading zones). These addresses are non routable.
func IsIP6LinkLocal(m ma.Multiaddr) bool {
return bytes.HasPrefix(m.Bytes(), []byte{ma.P_IP6, 0xfe, 0x80})
matched := false
ma.ForEach(m, func(c ma.Component) bool {
// Too much.
if matched {
matched = false
return false
}
switch c.Protocol().Code {
case ma.P_IP6ZONE:
return true
case ma.P_IP6:
ip := net.IP(c.RawValue())
matched = ip.IsLinkLocalMulticast() || ip.IsLinkLocalUnicast()
return true
default:
return false
}
})
return matched
}
// IsIPUnspecified returns whether a Multiaddr is am Unspecified IP address

6
net_test.go
View File

@ -322,6 +322,10 @@ func TestIPLoopback(t *testing.T) {
t.Error("IsIPLoopback false positive (/ip4/112.123.11.1)")
}
if IsIPLoopback(newMultiaddr(t, "/ip4/127.0.0.1/ip4/127.0.0.1")) {
t.Error("IsIPLoopback false positive (/ip4/127.0.0.1/127.0.0.1)")
}
if IsIPLoopback(newMultiaddr(t, "/ip4/192.168.0.1/ip6/::1")) {
t.Error("IsIPLoopback false positive (/ip4/192.168.0.1/ip6/::1)")
}
@ -363,7 +367,7 @@ func TestIPUnspecified(t *testing.T) {
func TestIP6LinkLocal(t *testing.T) {
for a := 0; a < 65536; a++ {
isLinkLocal := (a == 0xfe80)
isLinkLocal := (a&0xffc0 == 0xfe80 || a&0xff0f == 0xff02)
m := newMultiaddr(t, fmt.Sprintf("/ip6/%x::1", a))
if IsIP6LinkLocal(m) != isLinkLocal {
t.Errorf("IsIP6LinkLocal failed (%s != %v)", m, isLinkLocal)