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net/stun: unmap IPv4 addresses in 16 byte STUN replies

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Updates #5602

Change-Id: I2276ad2bfb415b9ff52f37444f2a1d74b38543b1
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick
2022-09-12 11:37:56 -07:00
committed by Brad Fitzpatrick
parent eb5939289c
commit 024257ef5a
2 changed files with 16 additions and 17 deletions
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24
net/stun/stun.go
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@ -208,7 +208,7 @@ func ParseResponse(b []byte) (tID TxID, addr netip.AddrPort, err error) {
b = b[:attrsLen] // trim trailing packet bytes
}
var addr6, fallbackAddr, fallbackAddr6 netip.AddrPort
var fallbackAddr netip.AddrPort
// Read through the attributes.
// The the addr+port reported by XOR-MAPPED-ADDRESS
@ -218,24 +218,20 @@ func ParseResponse(b []byte) (tID TxID, addr netip.AddrPort, err error) {
if err := foreachAttr(b, func(attrType uint16, attr []byte) error {
switch attrType {
case attrXorMappedAddress, attrXorMappedAddressAlt:
a, p, err := xorMappedAddress(tID, attr)
ipSlice, port, err := xorMappedAddress(tID, attr)
if err != nil {
return err
}
if len(a) == 16 {
addr6 = netip.AddrPortFrom(netip.AddrFrom16(*(*[16]byte)([]byte(a))), p)
} else {
addr = netip.AddrPortFrom(netip.AddrFrom4(*(*[4]byte)([]byte(a))), p)
if ip, ok := netip.AddrFromSlice(ipSlice); ok {
addr = netip.AddrPortFrom(ip.Unmap(), port)
}
case attrMappedAddress:
a, p, err := mappedAddress(attr)
ipSlice, port, err := mappedAddress(attr)
if err != nil {
return ErrMalformedAttrs
}
if len(a) == 16 {
fallbackAddr6 = netip.AddrPortFrom(netip.AddrFrom16(*(*[16]byte)([]byte(a))), p)
} else {
fallbackAddr = netip.AddrPortFrom(netip.AddrFrom4(*(*[4]byte)([]byte(a))), p)
if ip, ok := netip.AddrFromSlice(ipSlice); ok {
fallbackAddr = netip.AddrPortFrom(ip.Unmap(), port)
}
}
return nil
@ -250,12 +246,6 @@ func ParseResponse(b []byte) (tID TxID, addr netip.AddrPort, err error) {
if fallbackAddr.IsValid() {
return tID, fallbackAddr, nil
}
if addr6.IsValid() {
return tID, addr6, nil
}
if fallbackAddr6.IsValid() {
return tID, fallbackAddr6, nil
}
return tID, netip.AddrPort{}, ErrMalformedAttrs
}