netfilter: nf_nat_snmp_basic: use ASN.1 decoder

The goal of this patch set are to use the ASN.1 decoder library to parse SNMP ASN.1 payload.

This patch set are same as previous patch
"[PATCH V2]netfilter: nf_nat_snmp_basic: use asn1 decoder library".

My test environment are below.

#Network
Client <-------------> Netfilter FW <-------------> SNMP Server
192.168.3.2 192.168.3.1 192.168.4.1 192.168.4.2

#FW commands

   iptables -t raw -I PREROUTING -p udp -m multiport --dports 161,162 \
	-j CT --helper snmp

echo 'file nf_nat_snmp_basic_main.c +p' > \
/sys/kernel/debug/dynamic_debug/control

#SNMP Server commands
sudo ip r a 192.168.3.2 via 192.168.4.1 dev enp2s0
#Client commands
sudo ip r a 192.168.4.2 via 192.168.3.1 dev enp3s0

To test basic snmp test, I used snmpwalk command because it is easy to use
snmpwalk -v <1 or 2c> -c public <ip address> OID
example)
snmpwalk -v 2c -c public 192.168.4.2 .1.3.6.1.2.1.4.21

so that we can see this message from dmesg.
"snmp_helper: 192.168.3.2 to 192.168.4.1"

And, to test snmp trap test, I used snmptrap command.

   snmptrap -v 1 -c public 192.168.3.2 .1 192.168.4.2 0 0 0 .1 a \
	192.168.4.2

snmptrap -v 2c -c public 192.168.3.2 .1 .1 .1 a 192.168.4.2

SNMPv1 trap includes two ip address in payload. so we can see below message twice.
"snmp_helper: 192.168.4.2 to 192.168.3.1"

If you want to see asn1 decoder debug message, please use below command echo 'file asn1_decoder.c +p' > /sys/kernel/debug/dynamic_debug/control

V5 :
- fix sparse error

V4 :
- rename nf_nat_snmp_basic.c to nf_nat_snmp_basic_main.c to fix compile error

V3 :
- be separated by previous patch.

V2 :
- Add missing nf_nat_snmp_basic.asn1 file

V1 :
- Initial patch

Taehee Yoo (5):
netfilter: nf_nat_snmp_basic: remove useless comment
netfilter: nf_nat_snmp_basic: remove debug parameter
netfilter: nf_nat_snmp_basic: replace ctinfo with dir.
netfilter: nf_nat_snmp_basic: use nf_ct_helper_log
netfilter: nf_nat_snmp_basic: use asn1 decoder library

 net/ipv4/netfilter/Kconfig                         |    1 +
 net/ipv4/netfilter/Makefile                        |    6 +
 net/ipv4/netfilter/nf_nat_snmp_basic.asn1          |  177 +++
 ...f_nat_snmp_basic.c => nf_nat_snmp_basic_main.c} | 1181 ++------------------
 4 files changed, 249 insertions(+), 1116 deletions(-)
 create mode 100644 net/ipv4/netfilter/nf_nat_snmp_basic.asn1
 rename net/ipv4/netfilter/{nf_nat_snmp_basic.c => nf_nat_snmp_basic_main.c} (15%)

2.9.3

Thanks, I'm going to apply to nf-next.

I've been postponing this to schedule time to test this intensively, but I've been failing to find the time.

Given you've done hard work on this, I'm going to trust you have tested this intensively, so we get no fallout.

And thanks for your patience.