diff options
Diffstat (limited to 'pkg/tcpip/network/ipv4/icmp.go')
| -rw-r--r-- | pkg/tcpip/network/ipv4/icmp.go | 27 |
1 files changed, 26 insertions, 1 deletions
diff --git a/pkg/tcpip/network/ipv4/icmp.go b/pkg/tcpip/network/ipv4/icmp.go index d1a82b584..8e27a6677 100644 --- a/pkg/tcpip/network/ipv4/icmp.go +++ b/pkg/tcpip/network/ipv4/icmp.go @@ -481,6 +481,22 @@ func (*icmpReasonFragmentationNeeded) isForwarding() bool { return true } +// icmpReasonHostUnreachable is an error in which the host specified in the +// internet destination field of the datagram is unreachable. +type icmpReasonHostUnreachable struct{} + +func (*icmpReasonHostUnreachable) isICMPReason() {} +func (*icmpReasonHostUnreachable) isForwarding() bool { + // If we hit a Host Unreachable error, then we know we are operating as a + // router. As per RFC 792 page 5, Destination Unreachable Message, + // + // In addition, in some networks, the gateway may be able to determine + // if the internet destination host is unreachable. Gateways in these + // networks may send destination unreachable messages to the source host + // when the destination host is unreachable. + return true +} + // returnError takes an error descriptor and generates the appropriate ICMP // error packet for IPv4 and sends it back to the remote device that sent // the problematic packet. It incorporates as much of that packet as @@ -537,7 +553,12 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) tcpip defer route.Release() p.mu.Lock() - netEP, ok := p.mu.eps[pkt.NICID] + // We retrieve an endpoint using the newly constructed route's NICID rather + // than the packet's NICID. The packet's NICID corresponds to the NIC on + // which it arrived, which isn't necessarily the same as the NIC on which it + // will be transmitted. On the other hand, the route's NIC *is* guaranteed + // to be the NIC on which the packet will be transmitted. + netEP, ok := p.mu.eps[route.NICID()] p.mu.Unlock() if !ok { return &tcpip.ErrNotConnected{} @@ -653,6 +674,10 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) tcpip icmpHdr.SetType(header.ICMPv4DstUnreachable) icmpHdr.SetCode(header.ICMPv4NetUnreachable) counter = sent.dstUnreachable + case *icmpReasonHostUnreachable: + icmpHdr.SetType(header.ICMPv4DstUnreachable) + icmpHdr.SetCode(header.ICMPv4HostUnreachable) + counter = sent.dstUnreachable case *icmpReasonFragmentationNeeded: icmpHdr.SetType(header.ICMPv4DstUnreachable) icmpHdr.SetCode(header.ICMPv4FragmentationNeeded) |