Introduce a new NET_RT_IFLISTL API to query the address list. It works

on extended and extensible structs if_msghdrl and ifa_msghdrl.  This
will allow us to extend both the msghdrl structs and eventually if_data
in the future without breaking the ABI.

Bump __FreeBSD_version to allow ports to more easily detect the new API.

Reviewed by:	glebius, brooks
MFC after:	3 days

1 files changed, 54 insertions, 0 deletions

diff --git a/sys/net/if.h b/sys/net/if.h
index a5c0ade..47292cb 100644
--- a/sys/net/if.h
+++ b/sys/net/if.h
@@ -244,6 +244,7 @@ struct if_data {
 /*
  * Message format for use in obtaining information about interfaces
  * from getkerninfo and the routing socket
+ * For the new, extensible interface see struct if_msghdrl below.
  */
 struct if_msghdr {
 	u_short	ifm_msglen;	/* to skip over non-understood messages */
@@ -256,8 +257,34 @@ struct if_msghdr {
 };
 
 /*
+ * The 'l' version shall be used by new interfaces, like NET_RT_IFLISTL.  It is
+ * extensible after ifm_data_off or within ifm_data.  Both the if_msghdr and
+ * if_data now have a member field detailing the struct length in addition to
+ * the routing message length.  Macros are provided to find the start of
+ * ifm_data and the start of the socket address strucutres immediately following
+ * struct if_msghdrl given a pointer to struct if_msghdrl.
+ */
+#define	IF_MSGHDRL_IFM_DATA(_l) \
+    (struct if_data *)((char *)(_l) + (_l)->ifm_data_off)
+#define	IF_MSGHDRL_RTA(_l) \
+    (void *)((uintptr_t)(_l) + (_l)->ifm_len)
+struct if_msghdrl {
+	u_short	ifm_msglen;	/* to skip over non-understood messages */
+	u_char	ifm_version;	/* future binary compatibility */
+	u_char	ifm_type;	/* message type */
+	int	ifm_addrs;	/* like rtm_addrs */
+	int	ifm_flags;	/* value of if_flags */
+	u_short	ifm_index;	/* index for associated ifp */
+	u_short _ifm_spare1;	/* spare space to grow if_index, see if_var.h */
+	u_short	ifm_len;	/* length of if_msghdrl incl. if_data */
+	u_short	ifm_data_off;	/* offset of if_data from beginning */
+	struct	if_data ifm_data;/* statistics and other data about if */
+};
+
+/*
  * Message format for use in obtaining information about interface addresses
  * from getkerninfo and the routing socket
+ * For the new, extensible interface see struct ifa_msghdrl below.
  */
 struct ifa_msghdr {
 	u_short	ifam_msglen;	/* to skip over non-understood messages */
@@ -270,6 +297,33 @@ struct ifa_msghdr {
 };
 
 /*
+ * The 'l' version shall be used by new interfaces, like NET_RT_IFLISTL.  It is
+ * extensible after ifam_metric or within ifam_data.  Both the ifa_msghdrl and
+ * if_data now have a member field detailing the struct length in addition to
+ * the routing message length.  Macros are provided to find the start of
+ * ifm_data and the start of the socket address strucutres immediately following
+ * struct ifa_msghdrl given a pointer to struct ifa_msghdrl.
+ */
+#define	IFA_MSGHDRL_IFAM_DATA(_l) \
+    (struct if_data *)((char *)(_l) + (_l)->ifam_data_off)
+#define	IFA_MSGHDRL_RTA(_l) \
+    (void *)((uintptr_t)(_l) + (_l)->ifam_len)
+struct ifa_msghdrl {
+	u_short	ifam_msglen;	/* to skip over non-understood messages */
+	u_char	ifam_version;	/* future binary compatibility */
+	u_char	ifam_type;	/* message type */
+	int	ifam_addrs;	/* like rtm_addrs */
+	int	ifam_flags;	/* value of ifa_flags */
+	u_short	ifam_index;	/* index for associated ifp */
+	u_short _ifam_spare1;	/* spare space to grow if_index, see if_var.h */
+	u_short	ifam_len;	/* length of ifa_msghdrl incl. if_data */
+	u_short	ifam_data_off;	/* offset of if_data from beginning */
+	int	ifam_metric;	/* value of ifa_metric */
+	struct	if_data ifam_data;/* statistics and other data about if or
+				 * address */
+};
+
+/*
  * Message format for use in obtaining information about multicast addresses
  * from the routing socket
  */