lib,zebra: do not enable link-params when a link-params command fails

A given interface has no enabled link-params context. If a link-params
configuration command fails, the link-params is wrongly enabled:

> r4(config-link-params)# no enable
> r4(config-link-params)# delay
>   (0-16777215)  Average delay in micro-second as decimal (0...16777215)
> r4(config-link-params)# delay 50 min 300 max 500
> Average delay should be comprise between Min (300) and Max (500) delay
> r4(config-link-params)# do sh run zebra
> (...)
> interface eth-rt1
> link-params
>  enable
> exit-link-params

link-params are enabled if and only if the interface structure has a
valid link_params pointer. Before checking the command validity,
if_link_params_get() is called to retrieve the link-params pointer.
However, this function initializes the pointer if it is NULL.

Only use if_link_params_get() to retrieve the pointer to avoid
confusion. In command setting functions, initialize the link_params
pointer if needed only after the validation of the command.

Fixes: 16f1b9e ("Update Traffic Engineering Support for OSPFD")
Signed-off-by: Louis Scalbert <louis.scalbert@6wind.com>

1 files changed, 21 insertions, 5 deletions

diff --git a/lib/if.c b/lib/if.c
index fa4fdb82d3..deb0690dcf 100644
--- a/lib/if.c
+++ b/lib/if.c
@@ -1095,13 +1095,15 @@ const char *if_link_type_str(enum zebra_link_type llt)
 
 struct if_link_params *if_link_params_get(struct interface *ifp)
 {
-	int i;
+	return ifp->link_params;
+}
 
-	if (ifp->link_params != NULL)
-		return ifp->link_params;
+struct if_link_params *if_link_params_enable(struct interface *ifp)
+{
+	struct if_link_params *iflp;
+	int i;
 
-	struct if_link_params *iflp =
-		XCALLOC(MTYPE_IF_LINK_PARAMS, sizeof(struct if_link_params));
+	iflp = if_link_params_init(ifp);
 
 	/* Compute default bandwidth based on interface */
 	iflp->default_bw =
@@ -1129,6 +1131,20 @@ struct if_link_params *if_link_params_get(struct interface *ifp)
 	return iflp;
 }
 
+struct if_link_params *if_link_params_init(struct interface *ifp)
+{
+	struct if_link_params *iflp = if_link_params_get(ifp);
+
+	if (iflp)
+		return iflp;
+
+	iflp = XCALLOC(MTYPE_IF_LINK_PARAMS, sizeof(struct if_link_params));
+
+	ifp->link_params = iflp;
+
+	return iflp;
+}
+
 void if_link_params_free(struct interface *ifp)
 {
 	XFREE(MTYPE_IF_LINK_PARAMS, ifp->link_params);