Re: [PATCH bpf-next v4 1/6] selftests/bpf: Add traffic monitor functions.

[Kui-Feng Lee <sinquersw@gmail.com>]

On 7/31/24 14:07, Stanislav Fomichev wrote:
> On 07/31, Kui-Feng Lee wrote:
>> Add functions that capture packets and print log in the background. They
>> are supposed to be used for debugging flaky network test cases. A monitored
>> test case should call traffic_monitor_start() to start a thread to capture
>> packets in the background for a given namespace and call
>> traffic_monitor_stop() to stop capturing. (Or, option '-m' implemented by
>> the later patches.)
>>
>>      IPv4 TCP packet: 127.0.0.1:48165 -> 127.0.0.1:36707, len 68, ifindex 1, SYN
>>      IPv4 TCP packet: 127.0.0.1:36707 -> 127.0.0.1:48165, len 60, ifindex 1, SYN, ACK
>>      IPv4 TCP packet: 127.0.0.1:48165 -> 127.0.0.1:36707, len 60, ifindex 1, ACK
>>      IPv4 TCP packet: 127.0.0.1:36707 -> 127.0.0.1:48165, len 52, ifindex 1, ACK
>>      IPv4 TCP packet: 127.0.0.1:48165 -> 127.0.0.1:36707, len 52, ifindex 1, FIN, ACK
>>      IPv4 TCP packet: 127.0.0.1:36707 -> 127.0.0.1:48165, len 52, ifindex 1, RST, ACK
>>      Packet file: packets-2172-86-select_reuseport:sockhash-test.log
>>      #280/87 select_reuseport/sockhash IPv4/TCP LOOPBACK test_detach_bpf:OK
>>
>> The above is the output of an example. It shows the packets of a connection
>> and the name of the file that contains captured packets in the directory
>> /tmp/tmon_pcap. The file can be loaded by tcpdump or wireshark.
>>
>> This feature only works if TRAFFIC_MONITOR variable has been passed to
>> build BPF selftests. For example,
>>
>>    make TRAFFIC_MONITOR=1 -C tools/testing/selftests/bpf
>>
>> This command will build BPF selftests with this feature enabled.
>>
>> Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
>> ---
>>   tools/testing/selftests/bpf/Makefile     |   5 +
>>   tools/testing/selftests/bpf/test_progs.c | 432 +++++++++++++++++++++++
>>   tools/testing/selftests/bpf/test_progs.h |  16 +
>>   3 files changed, 453 insertions(+)
>>
>> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
>> index 774c6270e377..0a3108311be7 100644
>> --- a/tools/testing/selftests/bpf/Makefile
>> +++ b/tools/testing/selftests/bpf/Makefile
>> @@ -41,6 +41,11 @@ CFLAGS += -g $(OPT_FLAGS) -rdynamic					\
>>   LDFLAGS += $(SAN_LDFLAGS)
>>   LDLIBS += $(LIBELF_LIBS) -lz -lrt -lpthread
>>   
>> +ifneq ($(TRAFFIC_MONITOR),)
>> +LDLIBS += -lpcap
>> +CFLAGS += -DTRAFFIC_MONITOR=1
>> +endif
> 
> Optionally: can make this more automagical with the following:
> 
> LDLIBS += $(shell pkg-config --libs 2>/dev/null)
> CFLAGS += $(shell pkg-config --cflags 2>/dev/null)
> CFLAGS += $(shell pkg-config --exists libpcap 2>/dev/null && echo "-DTRAFFIC_MONITOR=1")

Sure! I will try it!