[PATCH V3 net-next 1/5] icmp: add support for RFC 8335 PROBE

[Andreas Roeseler <andreas.a.roeseler@gmail.com>]

Add definitions for PROBE ICMP types and codes.

Add AFI definitions for IP and IPV6 as specified by IANA

Add a struct to represent the additional header when probing by IP
address (ctype == 3) for use in parsing incoming PROBE messages.

Add a struct to represent the entire Interface Identification Object
(IIO) section of an incoming PROBE packet

Signed-off-by: Andreas Roeseler <andreas.a.roeseler@gmail.com>
---
Changes since v1:
 - Add AFI_IP and AFI_IP6 definitions

Changes since v2:
Suggested by Willem de Brujin <willemdebrujin.kernel@gmail.com>
 - Add prefix for PROBE specific defined variables
 - Create struct icmp_ext_echo_iio for parsing incoming packet
---
 include/uapi/linux/icmp.h | 40 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/include/uapi/linux/icmp.h b/include/uapi/linux/icmp.h
index fb169a50895e..166ca77561de 100644
--- a/include/uapi/linux/icmp.h
+++ b/include/uapi/linux/icmp.h
@@ -66,6 +66,23 @@
 #define ICMP_EXC_TTL		0	/* TTL count exceeded		*/
 #define ICMP_EXC_FRAGTIME	1	/* Fragment Reass time exceeded	*/
 
+/* Codes for EXT_ECHO (PROBE) */
+#define ICMP_EXT_ECHO		42
+#define ICMP_EXT_ECHOREPLY	43
+#define ICMP_EXT_MAL_QUERY	1	/* Malformed Query */
+#define ICMP_EXT_NO_IF		2	/* No such Interface */
+#define ICMP_EXT_NO_TABLE_ENT	3	/* No such Table Entry */
+#define ICMP_EXT_MULT_IFS	4	/* Multiple Interfaces Satisfy Query */
+
+/* constants for EXT_ECHO (PROBE) */
+#define EXT_ECHOREPLY_ACTIVE	(1 << 2)/* position of active flag in reply */
+#define EXT_ECHOREPLY_IPV4	(1 << 1)/* position of ipv4 flag in reply */
+#define EXT_ECHOREPLY_IPV6	1	/* position of ipv6 flag in reply */
+#define EXT_ECHO_CTYPE_NAME	1
+#define EXT_ECHO_CTYPE_INDEX	2
+#define EXT_ECHO_CTYPE_ADDR	3
+#define EXT_ECHO_AFI_IP		1	/* Address Family Identifier for IPV4 */
+#define EXT_ECHO_AFI_IP6	2	/* Address Family Identifier for IPV6 */
 
 struct icmphdr {
   __u8		type;
@@ -118,4 +135,27 @@ struct icmp_extobj_hdr {
 	__u8		class_type;
 };
 
+/* RFC 8335: 2.1 Header for C-type 3 payload */
+struct icmp_ext_echo_ctype3_hdr {
+	__u16		afi;
+	__u8		addrlen;
+	__u8		reserved;
+};
+
+/* RFC 8335: Interface Identification Object */
+struct icmp_ext_echo_iio {
+	struct icmp_extobj_hdr	extobj_hdr;
+	union {
+		__u32	ifIndex;
+		char name;
+		struct {
+			struct icmp_ext_echo_ctype3_hdr	ctype3_hdr;
+			union {
+				__be32		ipv4_addr;
+				struct in6_addr	ipv6_addr;
+			} ip_addr;
+		} addr;
+	} ident;
+};
+
 #endif /* _UAPI_LINUX_ICMP_H */
-- 
2.25.1