net: ppp: Add proper support to receive Echo-Reply message

Currently only net-shell calls net_ppp_ping() command, so make
it return the amount of time that it took to receive Echo-Reply
so the net-shell can print the round trip time value.

Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>

include/net/ppp.h

@@ -182,6 +182,17 @@ enum ipv6cp_option_type {
 	IPV6CP_OPTION_INTERFACE_IDENTIFIER = 1,
 } __packed;
 
+/**
+ * @typedef net_ppp_lcp_echo_reply_cb_t
+ * @brief A callback function that can be called if a Echo-Reply needs to
+ *        be received.
+ * @param user_data User settable data that is passed to the callback
+ *        function.
+ * @param user_data_len Length of the user data.
+ */
+typedef void (*net_ppp_lcp_echo_reply_cb_t)(void *user_data,
+					    size_t user_data_len);
+
 /**
  * Generic PPP Finite State Machine
  */
@@ -427,6 +438,18 @@ struct ppp_context {
 
 #if defined(CONFIG_NET_SHELL)
 	struct {
+		struct {
+			/** Callback to be called when Echo-Reply is received.
+			 */
+			net_ppp_lcp_echo_reply_cb_t cb;
+
+			/** User specific data for the callback */
+			void *user_data;
+
+			/** User data length */
+			size_t user_data_len;
+		} echo_reply;
+
 		/** Used when waiting Echo-Reply */
 		struct k_sem wait_echo_reply;
 

subsys/net/ip/net_shell.c

@@ -3101,6 +3101,15 @@ static int cmd_net_ppp_ping(const struct shell *shell, size_t argc,
 			} else {
 				PR_INFO("PPP Echo-Req failed (%d)\n", ret);
 			}
+		} else {
+			if (ret > 1000) {
+				PR_INFO("%s%d msec\n",
+					"Received PPP Echo-Reply in ",
+					ret / 1000);
+			} else {
+				PR_INFO("%s%d usec\n",
+					"Received PPP Echo-Reply in ", ret);
+			}
 		}
 	} else {
 		PR_INFO("PPP network interface must be given.\n");

subsys/net/l2/ppp/fsm.c

@@ -1109,7 +1109,16 @@ enum net_verdict ppp_fsm_recv_echo_reply(struct ppp_fsm *fsm,
 	NET_DBG("[%s/%p] Current state %s (%d)", fsm->name, fsm,
 		ppp_state_str(fsm->state), fsm->state);
 
-	return NET_DROP;
+#if defined(CONFIG_NET_SHELL)
+	struct ppp_context *ctx = CONTAINER_OF(fsm, struct ppp_context,
+					       lcp.fsm);
+	if (ctx->shell.echo_reply.cb) {
+		ctx->shell.echo_reply.cb(ctx->shell.echo_reply.user_data,
+					 ctx->shell.echo_reply.user_data_len);
+	}
+#endif /* CONFIG_NET_SHELL */
+
+	return NET_OK;
 }
 
 enum net_verdict ppp_fsm_recv_discard_req(struct ppp_fsm *fsm,

subsys/net/l2/ppp/ppp_l2.c

@@ -7,6 +7,7 @@
 #include <logging/log.h>
 LOG_MODULE_REGISTER(net_l2_ppp, CONFIG_NET_L2_PPP_LOG_LEVEL);
 
+#include <stdlib.h>
 #include <net/net_core.h>
 #include <net/net_l2.h>
 #include <net/net_if.h>
@@ -336,6 +337,19 @@ static int get_ppp_context(int idx, struct ppp_context **ctx,
 	return 0;
 }
 
+static void echo_reply_handler(void *user_data, size_t user_data_len)
+{
+	struct ppp_context *ctx = user_data;
+	u32_t end_time = k_cycle_get_32();
+	int time_diff;
+
+	time_diff = abs(end_time - ctx->shell.echo_req_data);
+	ctx->shell.echo_req_data =
+		SYS_CLOCK_HW_CYCLES_TO_NS64(time_diff) / 1000;
+
+	k_sem_give(&ctx->shell.wait_echo_reply);
+}
+
 int net_ppp_ping(int idx, s32_t timeout)
 {
 	struct ppp_context *ctx;
@@ -347,7 +361,10 @@ int net_ppp_ping(int idx, s32_t timeout)
 		return ret;
 	}
 
-	ctx->shell.echo_req_data = sys_rand32_get();
+	ctx->shell.echo_req_data = k_cycle_get_32();
+	ctx->shell.echo_reply.cb = echo_reply_handler;
+	ctx->shell.echo_reply.user_data = ctx;
+	ctx->shell.echo_reply.user_data_len = sizeof(ctx);
 
 	ret = ppp_send_pkt(&ctx->lcp.fsm, iface, PPP_ECHO_REQ, 0,
 			   UINT_TO_POINTER(ctx->shell.echo_req_data),
@@ -356,7 +373,16 @@ int net_ppp_ping(int idx, s32_t timeout)
 		return ret;
 	}
 
-	return k_sem_take(&ctx->shell.wait_echo_reply, timeout);
+	ret = k_sem_take(&ctx->shell.wait_echo_reply, timeout);
+
+	ctx->shell.echo_reply.cb = NULL;
+
+	if (ret < 0) {
+		return ret;
+	}
+
+	/* Returns amount of microseconds waited */
+	return ctx->shell.echo_req_data;
 }
 
 struct ppp_context *net_ppp_context_get(int idx)