src: add tcp option reset support

This allows to replace a tcp option with nops, similar
to the TCPOPTSTRIP feature of iptables.

Signed-off-by: Florian Westphal <fw@strlen.de>

3 files changed, 53 insertions, 0 deletions

diff --git a/tests/py/any/tcpopt.t b/tests/py/any/tcpopt.t
index 3d4be2a2..177f01c4 100644
--- a/tests/py/any/tcpopt.t
+++ b/tests/py/any/tcpopt.t
@@ -54,3 +54,9 @@ tcp option mptcp exists;ok
 tcp option mptcp subtype 0;ok
 tcp option mptcp subtype 1;ok
 tcp option mptcp subtype { 0, 2};ok
+
+reset tcp option mptcp;ok
+reset tcp option 2;ok;reset tcp option maxseg
+reset tcp option 123;ok
+reset tcp option meh;fail
+reset tcp option 256;fail
diff --git a/tests/py/any/tcpopt.t.json b/tests/py/any/tcpopt.t.json
index 5cc6f8f4..4466f14f 100644
--- a/tests/py/any/tcpopt.t.json
+++ b/tests/py/any/tcpopt.t.json
@@ -585,3 +585,38 @@
         }
    }
 ]
+
+# reset tcp option mptcp
+[
+    {
+        "reset": {
+            "tcp option": {
+                "name": "mptcp"
+            }
+        }
+    }
+]
+
+# reset tcp option 2
+[
+    {
+        "reset": {
+            "tcp option": {
+                "name": "maxseg"
+            }
+        }
+    }
+]
+
+# reset tcp option 123
+[
+    {
+        "reset": {
+            "tcp option": {
+                "base": 123,
+                "len": 0,
+                "offset": 0
+            }
+        }
+    }
+]
diff --git a/tests/py/any/tcpopt.t.payload b/tests/py/any/tcpopt.t.payload
index 121cc97f..99b8985f 100644
--- a/tests/py/any/tcpopt.t.payload
+++ b/tests/py/any/tcpopt.t.payload
@@ -188,3 +188,15 @@ inet
   [ exthdr load tcpopt 1b @ 30 + 2 => reg 1 ]
   [ bitwise reg 1 = ( reg 1 & 0x000000f0 ) ^ 0x00000000 ]
   [ lookup reg 1 set __set%d ]
+
+# reset tcp option mptcp
+ip test-ip4 input
+  [ exthdr reset tcpopt 30 ]
+
+# reset tcp option 2
+ip test-ip4 input
+  [ exthdr reset tcpopt 2 ]
+
+# reset tcp option 123
+ip test-ip4 input
+  [ exthdr reset tcpopt 123 ]