mcumgr: client: Allow specifying server address

- Currently, it is not possible to use mcumgr client with smp server
  since there is no way to specify smp server address for requests.
- This patch series adds support for creating smp_client_object
  containing information regarding the host server. This design allows
  multiple smp_client_object to exist for the same underlying smp_udp
  transport, making it much easier to use the same udp socket for multiple
  OTAs.

Signed-off-by: Ayush Singh <ayush@beagleboard.org>

Author: Ayush1325

include/zephyr/mgmt/mcumgr/smp/smp_client.h

@@ -32,6 +32,8 @@ struct smp_client_object {
 	struct smp_transport *smpt;
 	/** SMP SEQ */
 	uint8_t smp_seq;
+	/** SMP transport data. Allows multiple client_object for single smp_transport. */
+	void *priv;
 };
 
 #ifdef __cplusplus
@@ -49,6 +51,27 @@ extern "C" {
  */
 int smp_client_object_init(struct smp_client_object *smp_client, int smp_type);
 
+/**
+ * @brief Set private data for SMP transport.
+ *
+ * @param smp_client	The Client to set private data for.
+ * @param data		SMP transport private data.
+ */
+static inline void smp_client_object_set_data(struct smp_client_object *smp_client, void *data)
+{
+	smp_client->priv = data;
+}
+
+/**
+ * @brief Get private data for SMP transport.
+ *
+ * @param smp_client	The Client to set private data for.
+ */
+static inline void *smp_client_object_get_data(struct smp_client_object *smp_client)
+{
+	return smp_client->priv;
+}
+
 /**
  * @brief Response callback for SMP send.
  *

include/zephyr/mgmt/mcumgr/transport/smp.h

@@ -91,6 +91,16 @@ typedef void (*smp_transport_ud_free_fn)(void *ud);
  */
 typedef bool (*smp_transport_query_valid_check_fn)(struct net_buf *nb, void *arg);
 
+/** @typedef smp_transport_ud_req_init_fn
+ * @brief SMP init request buffer
+ *
+ * The supplied net_buf should be for a SMP request
+ *
+ * @param nb                    net buf for SMP request
+ * @param priv			SMP transport private data
+ */
+typedef void (*smp_transport_ud_req_init_fn)(struct net_buf *nb, void *priv);
+
 /**
  * @brief Function pointers of SMP transport functions, if a handler is NULL then it is not
  * supported/implemented.
@@ -110,6 +120,9 @@ struct smp_transport_api_t {
 
 	/** Transport's check function for if a query is valid. */
 	smp_transport_query_valid_check_fn query_valid_check;
+
+	/** Transport's request buffer init function */
+	smp_transport_ud_req_init_fn ud_init;
 };
 
 /**

include/zephyr/mgmt/mcumgr/transport/smp_udp.h

@@ -14,6 +14,9 @@
 #ifndef ZEPHYR_INCLUDE_MGMT_SMP_UDP_H_
 #define ZEPHYR_INCLUDE_MGMT_SMP_UDP_H_
 
+#include <zephyr/mgmt/mcumgr/smp/smp_client.h>
+#include <zephyr/net/net_ip.h>
+
 /**
  * @brief This allows to use the MCUmgr SMP protocol over UDP.
  * @defgroup mcumgr_transport_udp UDP transport
@@ -46,6 +49,18 @@ int smp_udp_open(void);
  */
 int smp_udp_close(void);
 
+#if defined(CONFIG_SMP_CLIENT) || defined(__DOXYGEN__)
+/**
+ * @brief	Set host address for smp_client_object
+ *
+ * @note	addr should be valid as long as obj is valid.
+ *
+ * @return	0 on success
+ * @return	-errno code on failure.
+ */
+int smp_client_udp_set_host_addr(struct smp_client_object *obj, struct sockaddr *addr);
+#endif
+
 #ifdef __cplusplus
 }
 #endif

subsys/mgmt/mcumgr/smp_client/src/client.c

@@ -256,7 +256,7 @@ struct net_buf *smp_client_buf_allocation(struct smp_client_object *smp_client,
 	struct net_buf *nb;
 	struct smp_hdr smp_header;
 
-	nb = smp_packet_alloc();
+	nb = smp_alloc_req(smp_client->smpt, smp_client_object_get_data(smp_client));
 
 	if (nb) {
 		/* Write SMP header with payload length 0 */

subsys/mgmt/mcumgr/transport/include/mgmt/mcumgr/transport/smp_internal.h

@@ -59,6 +59,16 @@ void smp_rx_req(struct smp_transport *smtp, struct net_buf *nb);
 struct k_work_q *smp_get_wq(void);
 #endif
 
+/**
+ * @brief Allocates a request buffer.
+ *
+ * @param arg		The streamer providing the callback.
+ *
+ * @return	Newly-allocated buffer on success
+ *		NULL on failure.
+ */
+struct net_buf *smp_alloc_req(void *arg, void *priv);
+
 /**
  * @brief Allocates a response buffer.
  *

subsys/mgmt/mcumgr/transport/src/smp.c

@@ -53,6 +53,32 @@ void smp_packet_free(struct net_buf *nb)
 	net_buf_unref(nb);
 }
 
+/**
+ * @brief Allocates a request buffer.
+ *
+ * @param arg		The streamer providing the callback.
+ * @param priv		The streamer private data.
+ *
+ * @return	Newly-allocated buffer on success
+ *		NULL on failure.
+ */
+struct net_buf *smp_alloc_req(void *arg, void *priv)
+{
+	struct net_buf *req_nb;
+	struct smp_transport *smpt = arg;
+
+	req_nb = smp_packet_alloc();
+	if (req_nb == NULL) {
+		return NULL;
+	}
+
+	if (smpt->functions.ud_init) {
+		smpt->functions.ud_init(req_nb, priv);
+	}
+
+	return req_nb;
+}
+
 /**
  * @brief Allocates a response buffer.
  *

subsys/mgmt/mcumgr/transport/src/smp_udp.c

@@ -163,6 +163,16 @@ static int smp_udp_ud_copy(struct net_buf *dst, const struct net_buf *src)
 	return MGMT_ERR_EOK;
 }
 
+static void smp_udp_ud_init(struct net_buf *nb, void *priv)
+{
+	struct sockaddr *ud = net_buf_user_data(nb);
+	const struct sockaddr *addr = priv;
+
+	if (addr) {
+		memcpy(ud, addr, sizeof(*addr));
+	}
+}
+
 static int create_socket(enum proto_type proto, int *sock)
 {
 	int tmp_sock;
@@ -438,6 +448,7 @@ static void smp_udp_start(void)
 	smp_udp_configs.ipv4.smp_transport.functions.output = smp_udp4_tx;
 	smp_udp_configs.ipv4.smp_transport.functions.get_mtu = smp_udp_get_mtu;
 	smp_udp_configs.ipv4.smp_transport.functions.ud_copy = smp_udp_ud_copy;
+	smp_udp_configs.ipv4.smp_transport.functions.ud_init = smp_udp_ud_init;
 
 	rc = smp_transport_init(&smp_udp_configs.ipv4.smp_transport);
 #ifdef CONFIG_SMP_CLIENT
@@ -460,6 +471,7 @@ static void smp_udp_start(void)
 	smp_udp_configs.ipv6.smp_transport.functions.output = smp_udp6_tx;
 	smp_udp_configs.ipv6.smp_transport.functions.get_mtu = smp_udp_get_mtu;
 	smp_udp_configs.ipv6.smp_transport.functions.ud_copy = smp_udp_ud_copy;
+	smp_udp_configs.ipv6.smp_transport.functions.ud_init = smp_udp_ud_init;
 
 	rc = smp_transport_init(&smp_udp_configs.ipv6.smp_transport);
 #ifdef CONFIG_SMP_CLIENT
@@ -483,4 +495,24 @@ static void smp_udp_start(void)
 #endif
 }
 
+#ifdef CONFIG_SMP_CLIENT
+int smp_client_udp_set_host_addr(struct smp_client_object *obj, struct sockaddr *addr)
+{
+#ifdef CONFIG_MCUMGR_TRANSPORT_UDP_IPV4
+	if (obj->smpt == smp_udp_configs.ipv4_transport.smpt && addr->sa_family == AF_INET) {
+		smp_client_object_set_data(obj, addr);
+		return 0;
+	}
+#endif
+#ifdef CONFIG_MCUMGR_TRANSPORT_UDP_IPV6
+	if (obj->smpt == smp_udp_configs.ipv6_transport.smpt && addr->sa_family == AF_INET6) {
+		smp_client_object_set_data(obj, addr);
+		return 0;
+	}
+#endif
+
+	return -EINVAL;
+}
+#endif
+
 MCUMGR_HANDLER_DEFINE(smp_udp, smp_udp_start);