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Bug #2986

closed

stream bypass not making callback as expected

Added by Phil Young about 5 years ago. Updated over 4 years ago.

Status:
Closed
Priority:
Normal
Assignee:
Target version:
Affected Versions:
Effort:
Difficulty:
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Description

I've been testing the bypass callback in the Napatech capture method. This callback works well when using the bypass option in the rule set. I'm trying to get this to work with tcp stream thresholds and think there may be a bug.

In my conf file I have modified the following options:

stream:
bypass: true
reassembly:
depth: 1kb

With this configuration I do not get callbacks when I input large flows from a pcap file.

Looking at the code in stream-tcp.c (line 4843) I noticed this code:

/* streams that hit depth */
if ((ssn->client.flags & STREAMTCP_STREAM_FLAG_DEPTH_REACHED) &&
(ssn->server.flags & STREAMTCP_STREAM_FLAG_DEPTH_REACHED)) {
/* we can call bypass callback, if enabled */
if (StreamTcpBypassEnabled()) {
PacketBypassCallback(p);
}
}
if ((ssn->client.flags & STREAMTCP_STREAM_FLAG_DEPTH_REACHED) ||
(ssn->server.flags & STREAMTCP_STREAM_FLAG_DEPTH_REACHED)) {
p->flags |= PKT_STREAM_NOPCAPLOG;
}

It appears that the first "if" statement is requiring the stream depth to reach the depth threshold on both directions of the flow before making the callback. I would expect this to trigger if only one direction of the flow reaches depth as it is in the second "if" statement. When I changed the && to || on my system I got the callback as expected.

Am I correct that this is a bug? Or, am I doing something wrong in my configuration? (If it is a bug the code a few lines down at 4872 is likely also a bug.)

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