On 31/10/2024 12:37, Sabrina Dubroca wrote:
2024-10-29, 11:47:24 +0100, Antonio Quartulli wrote:
@@ -136,6 +139,10 @@ void ovpn_decrypt_post(void *data, int ret)
                goto drop;
        }
+ /* increment RX stats */
+       ovpn_peer_stats_increment_rx(&peer->vpn_stats, skb->len);
+       ovpn_peer_stats_increment_rx(&peer->link_stats, orig_len);

[I don't know much about the userspace implementation, so maybe this
is a silly question]

What's the value of keeping track of 2 separate stats if they are
incremented exactly at the same time? Packet count will be the same,
and the difference in bytes will be just measuring the encap overhead.

Should one of them be "packets/individual messages that get received
over the UDP/TCP link" and the other "packets that get passed up to
the stack"?

You're correct: link_stats if "received over the TCP/UDP socket", while vpn_stats if what is passing through the ovpn virtual device.

Packet count may not match though, for example when something happens between "received packet on the link" and "packet passed up to the device" (i.e. decryption error).

This makes me wonder why we increment them at the very same place....
link_stats should be increased upon RX from the socket, while vpn_stats just before delivery. I'll double check.



@@ -197,6 +206,8 @@ void ovpn_encrypt_post(void *data, int ret)
                goto err;
skb_mark_not_on_list(skb);
+       ovpn_peer_stats_increment_tx(&peer->link_stats, skb->len);
+       ovpn_peer_stats_increment_tx(&peer->vpn_stats, orig_len);
switch (peer->sock->sock->sk->sk_protocol) {
        case IPPROTO_UDP:

And on TX maybe something like "packets that the stack wants to send
through the tunnel" and "packets that actually make it onto the
UDP/TCP socket after encap/encrypt"?

Correct.

Same issue here. Increments should not happen back to back.


Thanks a lot for spotting these.

Regards,




--
Antonio Quartulli
OpenVPN Inc.


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