VPP-1294: add missing feature arc constraint

the ip4-dhcp-client-detect feature MUST run prior to nat44-out2in, or
inbound dhcp broadcast packets will be dropped. Certain dhcp servers
answer lease renewal dhcp-request packets with broadcast dhcp-acks, leading
to unrecoverable lease loss.

In detail, this constraint:

VNET_FEATURE_INIT (ip4_snat_out2in, static) = {
  .arc_name = "ip4-unicast",
  .node_name = "nat44-out2in",
  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa"),
};

doesn't get the job done:

ip4-unicast:
  [17] nat44-out2in
  [23] ip4-dhcp-client-detect
  [26] ip4-not-enabled

Add a proper constraint:

VNET_FEATURE_INIT (ip4_snat_out2in, static) = {
  .arc_name = "ip4-unicast",
  .node_name = "nat44-out2in",
  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa",
                               "ip4-dhcp-client-detect"),
};

and the interface feature order is OK, at least in this regard:

ip4-unicast:
  [17] ip4-dhcp-client-detect
  [18] nat44-out2in
  [26] ip4-not-enabled

We need to carefully audit (especially) the ip4-unicast feature arc,
which has [gasp] 37 features on it!

Change-Id: I5e749ead7ab2a25d80839a331de6261e112977ad
Signed-off-by: Dave Barach <dave@barachs.net>

1 files changed, 40 insertions, 6 deletions

diff --git a/src/vnet/feature/feature.c b/src/vnet/feature/feature.c
index 714e20e8e72..e1cea21d7b6 100644
--- a/src/vnet/feature/feature.c
+++ b/src/vnet/feature/feature.c
@@ -250,6 +250,14 @@ vnet_feature_enable_disable (const char *arc_name, const char *node_name,
 						 n_feature_config_bytes);
 }
 
+static int
+feature_cmp (void *a1, void *a2)
+{
+  vnet_feature_registration_t *reg1 = a1;
+  vnet_feature_registration_t *reg2 = a2;
+
+  return (int) reg1->feature_index - reg2->feature_index;
+}
 
 /** Display the set of available driver features.
     Useful for verifying that expected features are present
@@ -262,24 +270,45 @@ show_features_command_fn (vlib_main_t * vm,
   vnet_feature_main_t *fm = &feature_main;
   vnet_feature_arc_registration_t *areg;
   vnet_feature_registration_t *freg;
+  vnet_feature_registration_t *feature_regs = 0;
+  int verbose = 0;
+
+  if (unformat (input, "verbose"))
+    verbose = 1;
 
   vlib_cli_output (vm, "Available feature paths");
 
   areg = fm->next_arc;
   while (areg)
     {
-      vlib_cli_output (vm, "%s:", areg->arc_name);
+      if (verbose)
+	vlib_cli_output (vm, "[%2d] %s:", areg->feature_arc_index,
+			 areg->arc_name);
+      else
+	vlib_cli_output (vm, "%s:", areg->arc_name);
+
       freg = fm->next_feature_by_arc[areg->feature_arc_index];
       while (freg)
 	{
-	  vlib_cli_output (vm, "  %s\n", freg->node_name);
+	  vec_add1 (feature_regs, freg[0]);
 	  freg = freg->next_in_arc;
 	}
 
+      vec_sort_with_function (feature_regs, feature_cmp);
 
+      vec_foreach (freg, feature_regs)
+      {
+	if (verbose)
+	  vlib_cli_output (vm, "  [%2d]: %s\n", freg->feature_index,
+			   freg->node_name);
+	else
+	  vlib_cli_output (vm, "  %s\n", freg->node_name);
+      }
+      vec_reset_length (feature_regs);
       /* next */
       areg = areg->next;
     }
+  vec_free (feature_regs);
 
   return 0;
 }
@@ -289,7 +318,7 @@ show_features_command_fn (vlib_main_t * vm,
  *
  * @cliexpar
  * Example:
- * @cliexcmd{show ip features}
+ * @cliexcmd{show features [verbose]}
  * @cliexend
  * @endparblock
 ?*/
@@ -306,7 +335,7 @@ VLIB_CLI_COMMAND (show_features_command, static) = {
  */
 
 void
-vnet_interface_features_show (vlib_main_t * vm, u32 sw_if_index)
+vnet_interface_features_show (vlib_main_t * vm, u32 sw_if_index, int verbose)
 {
   vnet_feature_main_t *fm = &feature_main;
   u32 node_index, current_config_index;
@@ -320,7 +349,7 @@ vnet_interface_features_show (vlib_main_t * vm, u32 sw_if_index)
   vlib_node_t *n;
   int i;
 
-  vlib_cli_output (vm, "Driver feature paths configured on %U...",
+  vlib_cli_output (vm, "Feature paths configured on %U...",
 		   format_vnet_sw_if_index_name,
 		   vnet_get_main (), sw_if_index);
 
@@ -361,7 +390,10 @@ vnet_interface_features_show (vlib_main_t * vm, u32 sw_if_index)
 	  feat = cfg->features + i;
 	  node_index = feat->node_index;
 	  n = vlib_get_node (vm, node_index);
-	  vlib_cli_output (vm, "  %v", n->name);
+	  if (verbose)
+	    vlib_cli_output (vm, "  [%2d] %v", feat->feature_index, n->name);
+	  else
+	    vlib_cli_output (vm, "  %v", n->name);
 	}
     }
 }
@@ -396,6 +428,8 @@ set_interface_features_command_fn (vlib_main_t * vm,
 	enable = 0;
       else
 	{
+	  if (feature_name && arc_name)
+	    break;
 	  error = unformat_parse_error (line_input);
 	  goto done;
 	}