icmp: Don't discard first reply sequence for a given echo ID2022_10_26.f212044

In pasta mode, ICMP and ICMPv6 echo sockets relay back to us any
reply we send: we're on the same host as the target, after all. We
discard them by comparing the last sequence we sent with the sequence
we receive.

However, on the first reply for a given identifier, the sequence
might be zero, depending on the implementation of ping(8): we need
another value to indicate we haven't sent any sequence number, yet.

Use -1 as initialiser in the echo identifier map.

This is visible with Busybox's ping, and was reported by Paul on the
integration at https://github.com/containers/podman/pull/16141, with:

  $ podman run --net=pasta alpine ping -c 2 192.168.188.1

...where only the second reply would be routed back.

Reported-by: Paul Holzinger <pholzing@redhat.com>
Fixes: 33482d5bf293 ("passt: Add PASTA mode, major rework")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 1 insertions, 0 deletions

diff --git a/icmp.h b/icmp.h
index 458ce31..275486d 100644
--- a/icmp.h
+++ b/icmp.h
@@ -15,6 +15,7 @@ void icmp_sock_handler(const struct ctx *c, union epoll_ref ref,
 int icmp_tap_handler(const struct ctx *c, int af, const void *addr,
 		     const struct pool *p, const struct timespec *now);
 void icmp_timer(const struct ctx *c, const struct timespec *ts);
+void icmp_init(void);
 
 /**
  * union icmp_epoll_ref - epoll reference portion for ICMP tracking