Device loses io.ReadWriteCloser + NewMultiQueueReader in favor of
Queues(n), which returns up to n tio.Queue objects; platforms without
multiqueue hand back their single queue and the interface sizes its
reader routines to what it actually got. Queue.Read returns a batch of
borrowed packets (single-element for every current backend) so a future
backend can deliver more than one packet per syscall without another
interface change.
The Linux poll/eventfd machinery moves out of tun_linux.go into the new
overlay/tio package: nonblocking fds, a shared shutdown eventfd owned by
the queue set, and pollfd arrays built on the stack so concurrent
writers parked in blockOnWrite no longer share Revents storage. Other
platforms wrap their existing one-datagram Read/Write in a singleQueue
adapter that owns a private scratch buffer, so multiqueue-by-sharing
devices (user, disabled) no longer race concurrent readers on one
buffer.
This is the tun-interface subset of better-tun-interface-ordering,
extracted at 18dc13b with none of the GSO/GRO offload mechanics and no
udp/sendmmsg changes.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
* firewall: add option to send REJECT replies
This change allows you to configure the firewall to send REJECT packets
when a packet is denied.
firewall:
# Action to take when a packet is not allowed by the firewall rules.
# Can be one of:
# `drop` (default): silently drop the packet.
# `reject`: send a reject reply.
# - For TCP, this will be a RST "Connection Reset" packet.
# - For other protocols, this will be an ICMP port unreachable packet.
outbound_action: drop
inbound_action: drop
These packets are only sent to established tunnels, and only on the
overlay network (currently IPv4 only).
$ ping -c1 192.168.100.3
PING 192.168.100.3 (192.168.100.3) 56(84) bytes of data.
From 192.168.100.3 icmp_seq=2 Destination Port Unreachable
--- 192.168.100.3 ping statistics ---
2 packets transmitted, 0 received, +1 errors, 100% packet loss, time 31ms
$ nc -nzv 192.168.100.3 22
(UNKNOWN) [192.168.100.3] 22 (?) : Connection refused
This change also modifies the smoke test to capture tcpdump pcaps from
both the inside and outside to inspect what is going on over the wire.
It also now does TCP and UDP packet tests using the Nmap version of
ncat.
* calculate seq and ack the same was as the kernel
The logic a bit confusing, so we copy it straight from how the kernel
does iptables `--reject-with tcp-reset`:
- https://github.com/torvalds/linux/blob/v5.19/net/ipv4/netfilter/nf_reject_ipv4.c#L193-L221
* cleanup
JackDoan