passt: Assorted fixes from "fresh eyes" review

A bunch of fixes not worth single commits at this stage, notably:

- make buffer, length parameter ordering consistent in ARP, DHCP,
  NDP handlers

- strict checking of buffer, message and option length in DHCP
  handler (a malicious client could have easily crashed it)

- set up forwarding for IPv4 and IPv6, and masquerading with nft for
  IPv4, from demo script

- get rid of separate slow and fast timers, we don't save any
  overhead that way

- stricter checking of buffer lengths as passed to tap handlers

- proper dequeuing from qemu socket back-end: I accidentally trashed
  messages that were bundled up together in a single tap read
  operation -- the length header tells us what's the size of the next
  frame, but there's no apparent limit to the number of messages we
  get with one single receive

- rework some bits of the TCP state machine, now passive and active
  connection closes appear to be robust -- introduce a new
  FIN_WAIT_1_SOCK_FIN state indicating a FIN_WAIT_1 with a FIN flag
  from socket

- streamline TCP option parsing routine

- track TCP state changes to stderr (this is temporary, proper
  debugging and syslogging support pending)

- observe that multiplying a number by four might very well change
  its value, and this happens to be the case for the data offset
  from the TCP header as we check if it's the same as the total
  length to find out if it's a duplicated ACK segment

- recent estimates suggest that the duration of a millisecond is
  closer to a million nanoseconds than a thousand of them, this
  trend is now reflected into the timespec_diff_ms() convenience
  routine

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/doc/demo.sh b/doc/demo.sh
index 3d20491..3735130 100755
--- a/doc/demo.sh
+++ b/doc/demo.sh
@@ -48,10 +48,17 @@ ip netns add passt
 ip link add veth_passt up netns passt type veth peer name veth_passt
 ip link set dev veth_passt up
 
+
 ip -n passt addr add 192.0.2.2/24 dev veth_passt
 ip addr add 192.0.2.1/24 dev veth_passt
 ip -n passt route add default via 192.0.2.1
 
+sysctl -w net.ipv4.ip_forward=1
+nft delete table passt_nat 2>/dev/null || :
+nft add table passt_nat
+nft 'add chain passt_nat postrouting { type nat hook postrouting priority -100 ; }'
+nft add rule passt_nat postrouting ip saddr 192.0.2.2 masquerade
+
 ipv6_addr="$(ipv6_devaddr "$(ipv6_dev)")"
 ipv6_passt="$(ipv6_mangle "${ipv6_addr}")"
 ndp_setup "${ipv6_passt}"
@@ -59,11 +66,15 @@ ip -n passt addr add "${ipv6_passt}/$(ipv6_mask "${ipv6_addr}")" dev veth_passt
 ip addr add "${ipv6_addr}" dev veth_passt
 passt_ll="$(ipv6_ll_addr "veth_passt")"
 main_ll="$(get_token "link/ether" $(ip -o li sh veth_passt))"
-ip -n passt neigh add "${passt_ll%%/*}" dev veth_passt lladdr "${main_ll}"
+ip neigh add "${passt_ll%%/*}" dev veth_passt lladdr "${main_ll}"
 ip -n passt route add default via "${passt_ll%%/*}" dev veth_passt
 
+sysctl -w net.ipv6.conf.all.forwarding=1
+
+
 ethtool -K veth_passt tx off
 ip netns exec passt ethtool -K veth_passt tx off
 ulimit -n 300000
 
+
 ip netns exec passt ./passt