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Don't mangle bs slice in TAP mode

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This commit is contained in:
Neil Alexander 2019-07-20 12:10:05 +01:00
parent 2582df752d
commit 36201895e7
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GPG Key ID: A02A2019A2BB0944
1 changed files with 11 additions and 7 deletions
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18
src/tuntap/iface.go
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@ -111,10 +111,10 @@ func (tun *TunAdapter) writer() error {
} }
func (tun *TunAdapter) reader() error { func (tun *TunAdapter) reader() error {
bs := make([]byte, 65535) recvd := make([]byte, 65535)
for { for {
// Wait for a packet to be delivered to us through the TUN/TAP adapter // Wait for a packet to be delivered to us through the TUN/TAP adapter
n, err := tun.iface.Read(bs) n, err := tun.iface.Read(recvd)
if err != nil { if err != nil {
if !tun.isOpen { if !tun.isOpen {
return err return err
@ -130,17 +130,21 @@ func (tun *TunAdapter) reader() error {
if tun.iface.IsTAP() { if tun.iface.IsTAP() {
// Set our offset to beyond the ethernet headers // Set our offset to beyond the ethernet headers
offset = tun_ETHER_HEADER_LENGTH offset = tun_ETHER_HEADER_LENGTH
// Check first of all that we can go beyond the ethernet headers
if len(recvd) <= offset {
continue
}
// If we detect an ICMP packet then hand it to the ICMPv6 module // If we detect an ICMP packet then hand it to the ICMPv6 module
if bs[offset+6] == 58 { if recvd[offset+6] == 58 {
// Found an ICMPv6 packet // Found an ICMPv6 packet
b := make([]byte, n) b := make([]byte, n)
copy(b, bs) copy(b, recvd)
go tun.icmpv6.ParsePacket(b) go tun.icmpv6.ParsePacket(b)
} }
// Then offset the buffer so that we can now just treat it as an IP
// packet from now on
bs = bs[offset:] // FIXME this breaks bs for the next read and means n is the wrong value
} }
// Offset the buffer from now on so that we can ignore ethernet frames if
// they are present
bs := recvd[offset:]
// From the IP header, work out what our source and destination addresses // From the IP header, work out what our source and destination addresses
// and node IDs are. We will need these in order to work out where to send // and node IDs are. We will need these in order to work out where to send
// the packet // the packet