From e7155622a288da924f2fca06ba9a51c1202ea387 Mon Sep 17 00:00:00 2001
From: Michael Scott <mike@foundries.io>
Date: Mon, 8 Jul 2019 11:04:15 -0700
Subject: [PATCH] net: lwm2m: add custom TLS credential load function pointer

Current implementation of LwM2M engine doesn't allow users a way
of overriding TLS credential load with custom function.  This
would be needed by an offloaded TLS stack where we don't want
to use standard Zephyr functions.

Let's add a load_credential function pointer to the LwM2M client
context which will be called when it's available.

Fixes: https://github.com/zephyrproject-rtos/zephyr/issues/17408

Signed-off-by: Michael Scott <mike@foundries.io>
---
 include/net/lwm2m.h                 |  5 +++++
 subsys/net/lib/lwm2m/lwm2m_engine.c | 21 ++++++++++++++-------
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/include/net/lwm2m.h b/include/net/lwm2m.h
index e70951e8583..424c8836bd4 100644
--- a/include/net/lwm2m.h
+++ b/include/net/lwm2m.h
@@ -71,6 +71,11 @@ struct lwm2m_ctx {
 	 *  LwM2M engine calls tls_credential_(add|delete)
 	 */
 	int tls_tag;
+
+	/** Client can set load_credentials function as a way of overriding
+	 *  the default behavior of load_tls_credential() in lwm2m_engine.c
+	 */
+	int (*load_credentials)(struct lwm2m_ctx *client_ctx);
 #endif
 	/** Flag to indicate if context should use DTLS.
 	 *  Enabled via the use of coaps:// protocol prefix in connection
diff --git a/subsys/net/lib/lwm2m/lwm2m_engine.c b/subsys/net/lib/lwm2m/lwm2m_engine.c
index ae73592b935..b56bf37a4af 100644
--- a/subsys/net/lib/lwm2m/lwm2m_engine.c
+++ b/subsys/net/lib/lwm2m/lwm2m_engine.c
@@ -3992,14 +3992,21 @@ int lwm2m_socket_start(struct lwm2m_ctx *client_ctx)
 #if defined(CONFIG_LWM2M_DTLS_SUPPORT)
 	int ret;
 
-	ret = load_tls_credential(client_ctx, 3, TLS_CREDENTIAL_PSK_ID);
-	if (ret < 0) {
-		return ret;
-	}
+	if (client_ctx->load_credentials) {
+		ret = client_ctx->load_credentials(client_ctx);
+		if (ret < 0) {
+			return ret;
+		}
+	} else {
+		ret = load_tls_credential(client_ctx, 3, TLS_CREDENTIAL_PSK_ID);
+		if (ret < 0) {
+			return ret;
+		}
 
-	ret = load_tls_credential(client_ctx, 5, TLS_CREDENTIAL_PSK);
-	if (ret < 0) {
-		return ret;
+		ret = load_tls_credential(client_ctx, 5, TLS_CREDENTIAL_PSK);
+		if (ret < 0) {
+			return ret;
+		}
 	}
 
 	if (client_ctx->use_dtls) {