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Check how wrapping is done in P4

master
Nico Schottelius 3 years ago
parent
commit
1a39c35e3b
  1. 34
      doc/plan.org
  2. 48
      p4app/wraptest.json
  3. 2
      p4src/actions_delta_checksum.p4
  4. 50
      p4src/wraptest.p4

34
doc/plan.org

@ -5274,6 +5274,40 @@ Still using scapy + adjusted diff:
gets
sum 0xc5f2 (incorrect -> 0xe7cf)
*** 2019-07-16: pcap for debugging tcp
pcap/tcp-udp-delta-2019-07-15-1454-h3.pcap
pcap/tcp-udp-delta-2019-07-15-1454-h1.pcap
*** 2019-07-16: pcap for debugging udp
pcap/tcp-udp-delta-2019-07-16-0856-h3.pcap
pcap/tcp-udp-delta-2019-07-16-0856-h1.pcap
*** 2019-07-16: testing with udp
- suspicion: missing some cases in tcp6
#+BEGIN_CENTER
p4@ubuntu:~$ mx h1 "echo V6-OK | socat - UDP6-LISTEN:2342"
p4@ubuntu:~/master-thesis/bin$ mx h3 "echo V4-OK | socat - UDP:10.1.1.1:2342"
#+END_CENTER
08:57:19.998299 IP6 (hlim 64, next-header UDP (17) payload length: 14)
2001:db8:1::a00:1.59997 > 2001:db8::1.2342: [bad udp cksum 0xd84c ->
0xd84b!] UDP, length 6
**** DONE Result: arp (partly?) missing?
CLOSED: [2019-07-16 Tue 11:00]
**** TODO Result: udp checksum wrong
- should be: 0xd84b
- is: 0xd84c
My code is +1 too high
*** DONE 2019-07-16: understood scapy code
CLOSED: [2019-07-16 Tue 11:25]
meta.v6sum = (bit<16>) ((((tmp>>8) & 0xff)|tmp<<8) & 0xffff) ;
This is used to correct endianness!
-> not needed in our case
** The NetPFGA saga
Problems encountered:

48
p4app/wraptest.json

@ -0,0 +1,48 @@
{
"program": "../p4src/wraptest.p4",
"switch": "simple_switch",
"compiler": "p4c",
"options": "--target bmv2 --arch v1model --std p4-16",
"switch_cli": "simple_switch_CLI",
"cli": true,
"pcap_dump": true,
"enable_log": true,
"topo_module": {
"file_path": "",
"module_name": "p4utils.mininetlib.apptopo",
"object_name": "AppTopoStrategies"
},
"controller_module": null,
"topodb_module": {
"file_path": "",
"module_name": "p4utils.utils.topology",
"object_name": "Topology"
},
"mininet_module": {
"file_path": "",
"module_name": "p4utils.mininetlib.p4net",
"object_name": "P4Mininet"
},
"topology": {
"assignment_strategy": "l2",
"auto_arp_tables": false,
"links": [["h1", "s1"], ["h2", "s1"], ["h3", "s1"], ["h4","s1"]],
"hosts": {
"h1": {
},
"h2": {
}
,
"h3": {
}
,
"h4": {
}
},
"switches": {
"s1": {
"cpu_port" : true
}
}
}
}

2
p4src/actions_delta_checksum.p4

@ -52,7 +52,7 @@ action v6sum() {
tmp = (tmp >> 16) + (tmp & 0xffff);
// tmp = tmp + (tmp >> 16);
tmp = ~tmp;
// meta.v6sum = (bit<16>) ((((tmp>>8) & 0xff)|tmp<<8) & 0xffff) ;
meta.v6sum = (bit<16>) tmp;
}

50
p4src/wraptest.p4

@ -0,0 +1,50 @@
/* -*- P4_16 -*- */
#include <core.p4>
#include <v1model.p4>
#include "headers.p4"
#include "parsers.p4"
control MyIngress(inout headers hdr,
inout metadata meta,
inout standard_metadata_t standard_metadata) {
/********************** APPLYING TABLES ***********************************/
apply {
if(hdr.tcp.isValid()) {
/* test wrap around */
hdr.tcp.checksum = 0xffff;
hdr.tcp.checksum = checksum + 2;
}
standard_metadata.egress_spec = 1;
}
}
control MyEgress(inout headers hdr,
inout metadata meta,
inout standard_metadata_t standard_metadata) {
apply {
}
}
control MyVerifyChecksum(inout headers hdr, inout metadata meta) {
apply {}
}
control MyComputeChecksum(inout headers hdr, inout metadata meta) {
apply {}
}
/*************************************************************************
*********************** S W I T C H *******************************
*************************************************************************/
V1Switch(
MyParser(),
MyVerifyChecksum(),
MyIngress(),
MyEgress(),
MyComputeChecksum(),
MyDeparser()
) main;
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