From 404d4ff0df7da505efdeaf22d90a1e009ddb6937 Mon Sep 17 00:00:00 2001
From: Nico Schottelius <nico@nico-notebook.schottelius.org>
Date: Wed, 27 Mar 2019 18:01:11 +0100
Subject: [PATCH] Begin checksumming icmp4

---
 doc/plan.org            |  7 +++++--
 p4src/checksums.p4      |  8 ++++++++
 p4src/headers.p4        |  6 +++++-
 p4src/static-mapping.p4 | 17 +++++++++++++++--
 4 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/doc/plan.org b/doc/plan.org
index 8affa87..6bdd04d 100644
--- a/doc/plan.org
+++ b/doc/plan.org
@@ -479,8 +479,10 @@ INFO:main:unhandled reassambled=<Ether  dst=00:00:0a:00:00:42 src=00:00:0a:00:00
 ***** DONE source correctly translated to 10.1.1.1
 ***** DONE destination correctly translated to 10.0.0.1 -> pings h3
 ***** DONE egress is correct, comes out at h3
-***** TODO protocol 58 is wrong -> should be 1
-**** TODO transform protocol specific: icmp6 -> icmp
+***** DONE protocol 58 is wrong -> should be 1
+***** DONE figure out switch() syntax
+***** TODO Calculate ICMP checksum
+***** TODO transform protocol specific: icmp6 -> icmp
 **** TODO transform protocol specific: icmp -> icmp6
 **** TODO Make switch answer IPv4 icmp echo request for
 **** TODO Add / check default route for v4 hosts
@@ -1402,6 +1404,7 @@ Only the destination network is matched for deciding on NAT64, as
 priority based double LPM is not supported. This limits a prefix to be
 used only in one network.
 *** References / Follow up
+**** RFC 1017 ICMP checksum https://tools.ietf.org/html/rfc1071
 **** RFC 2460 IPv6 (Checksum https://tools.ietf.org/html/rfc2460#section-8.1)
 **** RFC 3810 MLD2 https://tools.ietf.org/html/rfc3810
 **** RFC 4443 ICMPv6 https://tools.ietf.org/html/rfc4443
diff --git a/p4src/checksums.p4 b/p4src/checksums.p4
index 1f38867..72818cf 100644
--- a/p4src/checksums.p4
+++ b/p4src/checksums.p4
@@ -60,6 +60,14 @@ control MyComputeChecksum(inout headers  hdr, inout metadata meta) {
             HashAlgorithm.csum16
         );
 
+        update_checksum_with_payload(meta.switch_task == TASK_CHECKSUM_ICMP,
+		 	{
+                hdr.icmp.type,
+                hdr.icmp.code
+            },
+            hdr.icmp.checksum,
+            HashAlgorithm.csum16
+        );
     }
 }
 
diff --git a/p4src/headers.p4 b/p4src/headers.p4
index dd8fe16..abc0920 100644
--- a/p4src/headers.p4
+++ b/p4src/headers.p4
@@ -38,6 +38,10 @@ const bit<8>  ICMP6_ECHO_REPLY   = 129;
 const bit<8>  ICMP6_NS           = 135;
 const bit<8>  ICMP6_NA           = 136;
 
+const bit<8>  ICMP_ECHO_REPLY    = 0;
+const bit<8>  ICMP_ECHO_REQUEST  = 8;
+
+
 /* RFC4861, Section 4.6 */
 const bit<8>  ICMP6_NDP_OPT_SOURCE_LL    = 1;
 const bit<8>  ICMP6_NDP_OPT_TARGET_LL    = 2;
@@ -52,6 +56,7 @@ const task_t TASK_DEBUG          = 3;
 const task_t TASK_ICMP6_REPLY    = 4;
 const task_t TASK_CHECKSUM_ICMP6    = 5; /* data plane */
 const task_t TASK_CHECKSUM_ICMP6_NA = 6; /* data plane */
+const task_t TASK_CHECKSUM_ICMP     = 7; /* data plane */
 
 
 /* 48+48+16 = 112 */
@@ -147,7 +152,6 @@ header icmp_t {
     bit<8>  type;
     bit<8>  code;
     bit<16> checksum;
-    bit<32> rest;
 }
 
 
diff --git a/p4src/static-mapping.p4 b/p4src/static-mapping.p4
index 100ff92..ecddf2b 100644
--- a/p4src/static-mapping.p4
+++ b/p4src/static-mapping.p4
@@ -54,7 +54,22 @@ control MyIngress(inout headers hdr,
     */
     action nat64_icmp6()
     {
+        hdr.icmp.setValid();
         hdr.ipv4.protocol = PROTO_ICMP; // overwrite generic same protocol assumption
+
+        switch(hdr.icmp6.type) {
+            ICMP6_ECHO_REQUEST: hdr.icmp.type = ICMP_ECHO_REQUEST;
+            ICMP6_ECHO_REPLY:   hdr.icmp.type = ICMP_ECHO_REPLY;
+        }
+
+        /* trigger checksumming */
+        meta.switch_task = TASK_CHECKSUM_ICMP;
+
+        hdr.icmp6.setInvalid();
+
+        /* not needed, as we don't translate them (yet/ever) */
+        hdr.icmp6_na_ns.setInvalid();
+        hdr.icmp6_option_link_layer_addr.setInvalid();
     }
 
 
@@ -120,8 +135,6 @@ control MyIngress(inout headers hdr,
 
         nat64_generic(src, dst);
 
-        /* fix the protocol specific translations */
-        // switch() ...
     }
 
     /* matching key: v4_network specified again */