add support for Recursive DNS Server (rfc6106)

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

2 files changed, 61 insertions, 0 deletions

diff --git a/libndp/libndp.c b/libndp/libndp.c
index d2b0bb6..95ae9f6 100644
--- a/libndp/libndp.c
+++ b/libndp/libndp.c
@@ -1009,6 +1009,10 @@ static struct ndp_msg_opt_type_info ndp_msg_opt_type_info_list[] =
 		.raw_struct_size = sizeof(struct __nd_opt_route_info),
 		.check_valid = ndp_msg_opt_route_check_valid,
 	},
+	[NDP_MSG_OPT_RDNSS] = {
+		.raw_type = __ND_OPT_RDNSS,
+		.raw_struct_size = sizeof(struct __nd_opt_rdnss),
+	},
 };
 
 #define NDP_MSG_OPT_TYPE_LIST_SIZE ARRAY_SIZE(ndp_msg_opt_type_info_list)
@@ -1349,6 +1353,54 @@ ndp_msg_opt_route_preference(struct ndp_msg *msg, int offset)
 	return (ri->nd_opt_ri_prf_reserved >> 3) & 3;
 }
 
+/**
+ * ndp_msg_opt_rdnss_lifetime:
+ * @msg: message structure
+ *
+ * Get Recursive DNS Server lifetime.
+ * User should use this function only inside ndp_msg_opt_for_each_offset()
+ * macro loop.
+ *
+ * Returns: route lifetime in seconds, (uint32_t) -1 means infinity.
+ **/
+NDP_EXPORT
+uint32_t ndp_msg_opt_rdnss_lifetime(struct ndp_msg *msg, int offset)
+{
+	struct __nd_opt_rdnss *rdnss =
+			ndp_msg_payload_opts_offset(msg, offset);
+
+	return ntohl(rdnss->nd_opt_rdnss_lifetime);
+}
+
+/**
+ * ndp_msg_opt_rdnss_addr:
+ * @msg: message structure
+ * @offset: in-message offset
+ * @addr_index: address index
+ *
+ * Get Recursive DNS Server address.
+ * User should use this function only inside ndp_msg_opt_for_each_offset()
+ * macro loop.
+ *
+ * Returns: address.
+ **/
+NDP_EXPORT
+struct in6_addr *ndp_msg_opt_rdnss_addr(struct ndp_msg *msg, int offset,
+					int addr_index)
+{
+	static struct in6_addr addr;
+	struct __nd_opt_rdnss *rdnss =
+			ndp_msg_payload_opts_offset(msg, offset);
+	size_t len = rdnss->nd_opt_rdnss_len << 3; /* convert to bytes */
+
+	len -= in_struct_offset(struct __nd_opt_rdnss, nd_opt_rdnss_addresses);
+	if ((addr_index + 1) * sizeof(addr) > len)
+		return NULL;
+	memcpy(&addr, &rdnss->nd_opt_rdnss_addresses[addr_index * sizeof(addr)],
+	       sizeof(addr));
+	return &addr;
+}
+
 static int ndp_call_handlers(struct ndp *ndp, struct ndp_msg *msg);
 
 static int ndp_sock_recv(struct ndp *ndp)
diff --git a/libndp/ndp_private.h b/libndp/ndp_private.h
index 7ab0ade..7424e8c 100644
--- a/libndp/ndp_private.h
+++ b/libndp/ndp_private.h
@@ -83,6 +83,7 @@ ndp_log_null(struct ndp *ndp, const char *format, ...) {}
  */
 
 #define __ND_OPT_ROUTE_INFO 24 /* rfc4191 */
+#define __ND_OPT_RDNSS 25 /* rfc6106 */
 
 struct __nd_opt_route_info { /* route information */
 	uint8_t		nd_opt_ri_type;
@@ -93,4 +94,12 @@ struct __nd_opt_route_info { /* route information */
 	char		nd_opt_ri_prefix[0];
 };
 
+struct __nd_opt_rdnss { /* Recursive DNS Server */
+	uint8_t		nd_opt_rdnss_type;
+	uint8_t		nd_opt_rdnss_len;
+	uint16_t	nd_opt_rdnss_reserved;
+	uint32_t	nd_opt_rdnss_lifetime;
+	char		nd_opt_rdnss_addresses[0];
+};
+
 #endif /* _NDP_PRIVATE_H_ */