[ovs-dev,5/6] Generic encap and decap support for NSH

From: Jan Scheurich [mailto:jan.scheurich@ericsson.com]

Thanks Jan, I have folded it to my local branch and will include it in next version.

-----Original Message-----
From: Jan Scheurich [mailto:jan.scheurich@ericsson.com] 
Sent: Tuesday, July 18, 2017 12:34 AM
To: Yang, Yi Y <yi.y.yang@intel.com>; dev@openvswitch.org
Subject: RE: [PATCH 5/6] Generic encap and decap support for NSH

Hi Yi,

The following incremental fills the gaps to support NSH TLV properties in encap(nsh) for MD2 format

BR, Jan

    Encap properties of type OFPPPT_PROP_NSH_TLV are mapped to structs
    nsh_md2_tlv during translation and concatenated in a new struct ofpbuf
    *encap_data in the translation ctx.

    At generation of the encap_nsh action, the sequence of MD2 TLVs is
    copied as byte array from *encap_data into the datapath action. In the
    datapath, encap_nsh copies the TLV metadata verbatim into the NSH MD2
    packet header.

    The decap_nsh action already skipped any metadata behind the basic NSH
    header based on the NSH header length attribute.

    Note: There is no support yet for parsing, matching and manipulating
    NSH MD2 TLVs as OXM fields. This will be added in a future contribution.

                     break;
                 }
                 case OFPPPT_PROP_NSH_TLV: {
-                    struct nsh_md2_tlv *md2_ctx = (struct nsh_md2_tlv *) p;
                     struct ofpact_ed_prop_nsh_tlv *tlv_prop =
                             (struct ofpact_ed_prop_nsh_tlv *) prop_ptr;
+                    struct nsh_md2_tlv *md2_ctx =
+                            ofpbuf_put_uninit(buf, sizeof(*md2_ctx));
                     md2_ctx->md_class = tlv_prop->tlv_class;
                     md2_ctx->type = tlv_prop->tlv_type;
                     md2_ctx->length = tlv_prop->tlv_len;
-                    len = ROUND_UP(md2_ctx->length, 4);
-                    padding = len - md2_ctx->length;
-                    if (p + len < buf + 512) {
-                        memcpy(md2_ctx->md_value, tlv_prop->data, md2_ctx->length);
-                        p += md2_ctx->length;
-                        memset(p, 0, padding);
-                        p += padding;
-                    }
+                    size_t len = ROUND_UP(md2_ctx->length, 4);
+                    size_t padding = len - md2_ctx->length;
+                    ofpbuf_put(buf, tlv_prop->data, md2_ctx->length);
+                    ofpbuf_put_zeros(buf, padding);
                     break;
                 }
                 default:
@@ -5516,6 +5521,10 @@ rewrite_flow_encap_nsh(struct xlate_ctx *ctx,
         }
         ptr += ROUND_UP(prop_ptr->len, 8);
     }
+    if (buf->size == 0 || buf->size >= OVS_ENCAP_NSH_MAX_MD_LEN) {
+        ofpbuf_delete(buf);
+        buf = NULL;
+    }

     /* Determine the Next Protocol field for NSH header. */
     switch (ntohl(packet_type)) {
@@ -5538,7 +5547,7 @@ rewrite_flow_encap_nsh(struct xlate_ctx *ctx,
                                "supported for packet type (%d,0x%x)",
                                pt_ns(packet_type), pt_ns_type(packet_type));
             ctx->error = 1;
-            return;
+            return buf;
     }
     /* Note that we have matched on packet_type! */
     wc->masks.packet_type = OVS_BE32_MAX; @@ -5560,10 +5569,16 @@ rewrite_flow_encap_nsh(struct xlate_ctx *ctx,
         flow->nsh.c2 = 0;
         flow->nsh.c3 = 0;
         flow->nsh.c4 = 0;
+        if (buf) {
+            /* Drop any MD2 context TLVs. */
+            ofpbuf_delete(buf);
+            buf = NULL;
+        }
     } else if (md_type == NSH_M_TYPE2) {
-        flow->nsh.mdtype = NSH_M_TYPE1;
-        /* TODO: Deal with TLV context headers stored in buf[512]. */
+        flow->nsh.mdtype = NSH_M_TYPE2;
     }
+
+    return buf;
 }

 static void
@@ -5572,6 +5587,7 @@ xlate_generic_encap_action(struct xlate_ctx *ctx,  {
     struct flow *flow = &ctx->xin->flow;
     struct flow_wildcards *wc = ctx->wc;
+    struct ofpbuf *encap_data = NULL;

     /* Ensure that any pending actions on the inner packet are applied before
      * rewriting the flow */
@@ -5583,7 +5599,7 @@ xlate_generic_encap_action(struct xlate_ctx *ctx,
             rewrite_flow_encap_ethernet(ctx, flow, wc);
             break;
         case PT_NSH:
-            rewrite_flow_encap_nsh(ctx, encap, flow, wc);
+            encap_data = rewrite_flow_encap_nsh(ctx, encap, flow, wc);
             break;
         default:
             /* New packet type was checked during decoding. */ @@ -5594,6 +5610,7 @@ xlate_generic_encap_action(struct xlate_ctx *ctx,
     if (!ctx->error) {
         /* The actual encap datapath action will be generated at next commit. */
         ctx->pending_encap = true;
+        ctx->encap_data = encap_data;
     }
 }

@@ -6495,6 +6512,7 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout)
         .in_action_set = false,
         .in_packet_out = xin->in_packet_out,
         .pending_encap = false,
+        .encap_data = NULL,

         .table_id = 0,
         .rule_cookie = OVS_BE64_MAX,
@@ -6841,6 +6859,7 @@ exit:
     ofpbuf_uninit(&ctx.action_set);
     ofpbuf_uninit(&ctx.frozen_actions);
     ofpbuf_uninit(&scratch_actions);
+    ofpbuf_delete(ctx.encap_data);

     /* Make sure we return a "drop flow" in case of an error. */
     if (ctx.error) {


[ovs-dev,5/6] Generic encap and decap support for NSH

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