add support for Default Router Preference in RA msg (rfc4191)

Signed-off-by: Jiri Pirko <jiri@resnulli.us>

3 files changed, 61 insertions, 11 deletions

diff --git a/include/ndp.h b/include/ndp.h
index 1c53358..6ce2c8b 100644
--- a/include/ndp.h
+++ b/include/ndp.h
@@ -86,6 +86,9 @@ void ndp_msgra_flag_other_set(struct ndp_msgra *msgra, bool flag_other);
 bool ndp_msgra_flag_home_agent(struct ndp_msgra *msgra);
 void ndp_msgra_flag_home_agent_set(struct ndp_msgra *msgra,
 				   bool flag_home_agent);
+enum ndp_route_preference ndp_msgra_route_preference(struct ndp_msgra *msgra);
+void ndp_msgra_route_preference_set(struct ndp_msgra *msgra,
+				    enum ndp_route_preference pref);
 uint16_t ndp_msgra_router_lifetime(struct ndp_msgra *msgra);
 void ndp_msgra_router_lifetime_set(struct ndp_msgra *msgra,
 				   uint16_t router_lifetime);
diff --git a/libndp/libndp.c b/libndp/libndp.c
index 8eaa16b..631abfb 100644
--- a/libndp/libndp.c
+++ b/libndp/libndp.c
@@ -853,6 +853,45 @@ void ndp_msgra_flag_home_agent_set(struct ndp_msgra *msgra,
 }
 
 /**
+ * ndp_msgra_route_preference:
+ * @msgra: RA message structure
+ *
+ * Get route preference.
+ *
+ * Returns: route preference.
+ **/
+NDP_EXPORT
+enum ndp_route_preference ndp_msgra_route_preference(struct ndp_msgra *msgra)
+{
+	uint8_t prf = (msgra->ra->nd_ra_flags_reserved >> 3) & 3;
+
+	/* rfc4191 says:
+	 * If the Router Lifetime is zero, the preference value MUST be set to
+	 * (00) by the sender and MUST be ignored by the receiver.
+	 * If the Reserved (10) value is received, the receiver MUST treat the
+	 * value as if it were (00).
+	 */
+	if (prf == 2 || !ndp_msgra_router_lifetime(msgra))
+		prf = 0;
+	return prf;
+}
+
+/**
+ * ndp_msgra_route_preference_set:
+ * @msgra: RA message structure
+ * @pref: preference
+ *
+ * Set route preference.
+ **/
+NDP_EXPORT
+void ndp_msgra_route_preference_set(struct ndp_msgra *msgra,
+				    enum ndp_route_preference pref)
+{
+	msgra->ra->nd_ra_flags_reserved &= ~(3 << 3);
+	msgra->ra->nd_ra_flags_reserved |= (pref << 3);
+}
+
+/**
  * ndp_msgra_router_lifetime:
  * @msgra: RA message structure
  *
diff --git a/utils/ndptool.c b/utils/ndptool.c
index 2898d61..8bc775b 100644
--- a/utils/ndptool.c
+++ b/utils/ndptool.c
@@ -164,6 +164,21 @@ static void pr_out_hwaddr(unsigned char *hwaddr, size_t len)
 	pr_out("\n");
 }
 
+static void pr_out_route_preference(enum ndp_route_preference pref)
+{
+	switch (pref) {
+	case NDP_ROUTE_PREF_LOW:
+		pr_out("low");
+		break;
+	case NDP_ROUTE_PREF_MEDIUM:
+		pr_out("medium");
+		break;
+	case NDP_ROUTE_PREF_HIGH:
+		pr_out("high");
+		break;
+	}
+}
+
 static int msgrcv_handler_func(struct ndp *ndp, struct ndp_msg *msg, void *priv)
 {
 	char ifname[IF_NAMESIZE];
@@ -185,6 +200,9 @@ static int msgrcv_handler_func(struct ndp *ndp, struct ndp_msg *msg, void *priv)
 		       ndp_msgra_flag_managed(msgra) ? "yes" : "no");
 		pr_out("  Other configuration: %s\n",
 		       ndp_msgra_flag_other(msgra) ? "yes" : "no");
+		pr_out("  Default router preference: ");
+		pr_out_route_preference(ndp_msgra_route_preference(msgra));
+		pr_out("\n");
 		pr_out("  Router lifetime: %us\n",
 		       ndp_msgra_router_lifetime(msgra));
 		pr_out("  Reachable time: ");
@@ -248,17 +266,7 @@ static int msgrcv_handler_func(struct ndp *ndp, struct ndp_msg *msg, void *priv)
 			else
 				pr_out("%us", lifetime);
 			pr_out(", preference: ");
-			switch (ndp_msg_opt_route_preference(msg, offset)) {
-			case NDP_ROUTE_PREF_LOW:
-				pr_out("low");
-				break;
-			case NDP_ROUTE_PREF_MEDIUM:
-				pr_out("medium");
-				break;
-			case NDP_ROUTE_PREF_HIGH:
-				pr_out("high");
-				break;
-			}
+			pr_out_route_preference(ndp_msg_opt_route_preference(msg, offset));
 			pr_out("\n");
 		}
 	} else if (msg_type == NDP_MSG_NS) {