From 52c4e8cec4dd560503ff011f8fe7eec5f67b33c9 Mon Sep 17 00:00:00 2001

From: Jerome Marchand <jmarchan@redhat.com>

Date: Thu, 17 Sep 2020 10:37:02 +0200

Subject: [PATCH 2/2] tools: tcptracer: fix alignement in tcp_ipv6_event_t

On IPv6, tcptracer ports always appears as zeros:

Tracing TCP established connections. Ctrl-C to end.

T  PID    COMM             IP SADDR            DADDR            SPORT  DPORT

X  7055   nc               4  127.0.0.1        127.0.0.1        49476  9999

C  7074   nc               4  127.0.0.1        127.0.0.1        49478  9999

X  7074   nc               4  127.0.0.1        127.0.0.1        49478  9999

C  7085   nc               6  [::]             [0:0:0:1::]      0      0

X  7085   nc               6  [::]             [0:0:0:1::]      0      0

C  7086   nc               6  [::]             [0:0:0:1::]      0      0

This seems related to alignment issue wrt to the __int128 type in

tcp_ipv6_event_t structure. Moving the u8 field ip to the end of the

structure fixes the issue.

Fixes #2781

---

 tools/tcptracer.py | 2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/tcptracer.py b/tools/tcptracer.py

index 2e486b15..3220105e 100755

--- a/tools/tcptracer.py

+++ b/tools/tcptracer.py

@@ -73,12 +73,12 @@ struct tcp_ipv6_event_t {

     u32 type;

     u32 pid;

     char comm[TASK_COMM_LEN];

-    u8 ip;

     unsigned __int128 saddr;

     unsigned __int128 daddr;

     u16 sport;

     u16 dport;

     u32 netns;

+    u8 ip;

 };

 BPF_PERF_OUTPUT(tcp_ipv6_event);

-- 

2.25.4