net/icmpv6: Allow for arbitrary payload data in ICMP echo

Allow for including arbitrary data in net_icmpv6_send_echo_request()
that will be echoed verbatim by the receiver.

This allows to use ICMP echo for diagnostic use cases, e.g. by testing
packet framentation (large payload) or measuring round-trip-time.

Signed-off-by: Benjamin Valentin <benjamin.valentin@ml-pa.com>

samples/net/zperf/src/zperf_shell.c

@@ -561,7 +561,7 @@ static int execute_upload(const struct shell *shell,
 		 * some time and start the test after that.
 		 */
 		net_icmpv6_send_echo_request(net_if_get_default(),
-					     &ipv6->sin6_addr, 0, 0);
+					     &ipv6->sin6_addr, 0, 0, NULL, 0);
 
 		k_sleep(K_SECONDS(1));
 	}

subsys/net/ip/icmpv6.c

@@ -297,7 +297,9 @@ drop_no_pkt:
 int net_icmpv6_send_echo_request(struct net_if *iface,
 				 struct in6_addr *dst,
 				 u16_t identifier,
-				 u16_t sequence)
+				 u16_t sequence,
+				 const void *data,
+				 size_t data_size)
 {
 	NET_PKT_DATA_ACCESS_CONTIGUOUS_DEFINE(icmpv6_access,
 					      struct net_icmpv6_echo_req);
@@ -309,7 +311,8 @@ int net_icmpv6_send_echo_request(struct net_if *iface,
 	src = net_if_ipv6_select_src_addr(iface, dst);
 
 	pkt = net_pkt_alloc_with_buffer(iface,
-					sizeof(struct net_icmpv6_echo_req),
+					sizeof(struct net_icmpv6_echo_req)
+					+ data_size,
 					AF_INET6, IPPROTO_ICMPV6,
 					PKT_WAIT_TIME);
 	if (!pkt) {
@@ -331,6 +334,7 @@ int net_icmpv6_send_echo_request(struct net_if *iface,
 	echo_req->sequence   = htons(sequence);
 
 	net_pkt_set_data(pkt, &icmpv6_access);
+	net_pkt_write(pkt, data, data_size);
 
 	net_pkt_cursor_init(pkt);
 	net_ipv6_finalize(pkt, IPPROTO_ICMPV6);

subsys/net/ip/icmpv6.h

@@ -178,13 +178,18 @@ int net_icmpv6_send_error(struct net_pkt *pkt, u8_t type, u8_t code,
  * to this Echo Request. May be zero.
  * @param sequence A sequence number to aid in matching Echo Replies
  * to this Echo Request. May be zero.
+ * @param data Arbitrary payload data that will be included in the
+ * Echo Reply verbatim. May be zero.
+ * @param data_size Size of the Payload Data in bytes. May be zero.
  *
  * @return Return 0 if the sending succeed, <0 otherwise.
  */
 int net_icmpv6_send_echo_request(struct net_if *iface,
 				 struct in6_addr *dst,
 				 u16_t identifier,
-				 u16_t sequence);
+				 u16_t sequence,
+				 const void *data,
+				 size_t data_size);
 
 void net_icmpv6_register_handler(struct net_icmpv6_handler *handler);
 void net_icmpv6_unregister_handler(struct net_icmpv6_handler *handler);

subsys/net/ip/net_shell.c

@@ -2703,7 +2703,9 @@ static int ping_ipv6(const struct shell *shell, char *host)
 	ret = net_icmpv6_send_echo_request(iface,
 					   &ipv6_target,
 					   sys_rand32_get(),
-					   sys_rand32_get());
+					   sys_rand32_get(),
+					   NULL,
+					   0);
 	if (ret) {
 		remove_ipv6_ping_handler();
 	} else {