net: mqtt: Modify SOCKS5 based connections

Current SOCKS5 based connections in mqtt are only
TCP (nonsecure) based. To support TLS based SOCKS5
connections, new methods needs to be introduced.

Instead, removed CONFIG_MQTT_LIB_SOCKS based implementation.
And now mqtt provides an api to set proxy
(mqtt_client_set_proxy()) details. That's enough,
socket layer will take care of making connections through
proxy server.

Fixes: #17037

Signed-off-by: Ravi kumar Veeramally <ravikumar.veeramally@linux.intel.com>

include/net/mqtt.h

@@ -27,6 +27,7 @@
 #include <zephyr.h>
 #include <zephyr/types.h>
 #include <net/tls_credentials.h>
+#include <net/net_ip.h>
 #include <sys/mutex.h>
 
 #ifdef __cplusplus
@@ -349,11 +350,6 @@ enum mqtt_transport_type {
 	MQTT_TRANSPORT_SECURE,
 #endif /* CONFIG_MQTT_LIB_TLS */
 
-#if defined(CONFIG_MQTT_LIB_SOCKS)
-	/** Use SOCKS5 proxy for MQTT connection. */
-	MQTT_TRANSPORT_SOCKS,
-#endif /* CONFIG_MQTT_LIB_SOCKS */
-
 	/** Shall not be used as a transport type.
 	 *  Indicator of maximum transport types possible.
 	 */
@@ -387,19 +383,14 @@ struct mqtt_transport {
 			struct mqtt_sec_config config;
 		} tls;
 #endif /* CONFIG_MQTT_LIB_TLS */
-
-#if defined(CONFIG_MQTT_LIB_SOCKS)
-		/* SOCKS5 proxy transport for MQTT */
-		struct {
-			/** Socket descriptor. */
-			int sock;
-
-			/** SOCKS5 proxy address. */
-			struct sockaddr_storage *proxy;
-		} socks5;
-#endif /* CONFIG_MQTT_LIB_SOCKS */
-
 	};
+
+#if defined(CONFIG_SOCKS)
+	struct {
+		struct sockaddr addr;
+		socklen_t addrlen;
+	} proxy;
+#endif
 };
 
 /** @brief MQTT internal state. */
@@ -505,6 +496,24 @@ struct mqtt_client {
  */
 void mqtt_client_init(struct mqtt_client *client);
 
+#if defined(CONFIG_SOCKS)
+/*
+ * @brief Set proxy server details
+ *
+ * @param[in] client Client instance for which the procedure is requested,
+ *                   Shall not be NULL.
+ * @param[in] proxy_addr Proxy server address.
+ * @param[in] addrlen Proxy server address length.
+ *
+ * @return 0 or a negative error code (errno.h) indicating reason of failure.
+ *
+ * @note Must be called before calling mqtt_connect().
+ */
+int mqtt_client_set_proxy(struct mqtt_client *client,
+			  struct sockaddr *proxy_addr,
+			  socklen_t addrlen);
+#endif
+
 /**
  * @brief API to request new MQTT client connection.
  *

subsys/net/lib/mqtt/CMakeLists.txt

@@ -14,7 +14,3 @@ zephyr_library_sources(
 zephyr_library_sources_ifdef(CONFIG_MQTT_LIB_TLS
   mqtt_transport_socket_tls.c
   )
-
-zephyr_library_sources_ifdef(CONFIG_MQTT_LIB_SOCKS
-  mqtt_transport_socks.c
-  )

subsys/net/lib/mqtt/Kconfig

@@ -32,10 +32,4 @@ config MQTT_LIB_TLS
 	help
 	  Enable TLS support for socket MQTT Library
 
-config MQTT_LIB_SOCKS
-	bool "SOCKS proxy support for socket MQTT Library"
-	select SOCKS
-	help
-	  Enable SOCKS proxy support for socket MQTT Library
-
 endif # MQTT_LIB

subsys/net/lib/mqtt/mqtt.c

@@ -171,6 +171,26 @@ void mqtt_client_init(struct mqtt_client *client)
 	client->keepalive = MQTT_KEEPALIVE;
 }
 
+#if defined(CONFIG_SOCKS)
+int mqtt_client_set_proxy(struct mqtt_client *client,
+			  struct sockaddr *proxy_addr,
+			  socklen_t addrlen)
+{
+	if (IS_ENABLED(CONFIG_SOCKS)) {
+		if (!client || !proxy_addr) {
+			return -EINVAL;
+		}
+
+		client->transport.proxy.addrlen = addrlen;
+		memcpy(&client->transport.proxy.addr, proxy_addr, addrlen);
+
+		return 0;
+	}
+
+	return -ENOTSUP;
+}
+#endif
+
 int mqtt_connect(struct mqtt_client *client)
 {
 	int err_code;

subsys/net/lib/mqtt/mqtt_transport.c

@@ -29,11 +29,6 @@ extern int mqtt_client_tls_read(struct mqtt_client *client, u8_t *data,
 extern int mqtt_client_tls_disconnect(struct mqtt_client *client);
 #endif /* CONFIG_MQTT_LIB_TLS */
 
-#if defined(CONFIG_MQTT_LIB_SOCKS)
-/* Transport handler functions for SOCKS5 proxy socket transport. */
-extern int mqtt_client_socks5_connect(struct mqtt_client *client);
-#endif /* CONFIG_MQTT_LIB_SOCKS */
-
 /**@brief Function pointer array for TCP/TLS transport handlers. */
 const struct transport_procedure transport_fn[MQTT_TRANSPORT_NUM] = {
 	{
@@ -50,14 +45,6 @@ const struct transport_procedure transport_fn[MQTT_TRANSPORT_NUM] = {
 		mqtt_client_tls_disconnect,
 	},
 #endif /* CONFIG_MQTT_LIB_TLS */
-#if defined(CONFIG_MQTT_LIB_SOCKS)
-	{
-		mqtt_client_socks5_connect,
-		mqtt_client_tcp_write,
-		mqtt_client_tcp_read,
-		mqtt_client_tcp_disconnect,
-	},
-#endif /* CONFIG_MQTT_LIB_SOCKS */
 };
 
 int mqtt_transport_connect(struct mqtt_client *client)

subsys/net/lib/mqtt/mqtt_transport_socket_tcp.c

@@ -35,6 +35,18 @@ int mqtt_client_tcp_connect(struct mqtt_client *client)
 		return -errno;
 	}
 
+#if defined(CONFIG_SOCKS)
+	if (client->transport.proxy.addrlen != 0) {
+		ret = setsockopt(client->transport.tcp.sock,
+				 SOL_SOCKET, SO_SOCKS5,
+				 &client->transport.proxy.addr,
+				 client->transport.proxy.addrlen);
+		if (ret < 0) {
+			return -errno;
+		}
+	}
+#endif
+
 	MQTT_TRC("Created socket %d", client->transport.tcp.sock);
 
 	size_t peer_addr_size = sizeof(struct sockaddr_in6);

subsys/net/lib/mqtt/mqtt_transport_socket_tls.c

@@ -38,6 +38,17 @@ int mqtt_client_tls_connect(struct mqtt_client *client)
 
 	MQTT_TRC("Created socket %d", client->transport.tls.sock);
 
+#if defined(CONFIG_SOCKS)
+	if (client->transport.proxy.addrlen != 0) {
+		ret = setsockopt(client->transport.tls.sock,
+				 SOL_SOCKET, SO_SOCKS5,
+				 &client->transport.proxy.addr,
+				 client->transport.proxy.addrlen);
+		if (ret < 0) {
+			return -errno;
+		}
+	}
+#endif
 	/* Set secure socket options. */
 	ret = setsockopt(client->transport.tls.sock, SOL_TLS, TLS_PEER_VERIFY,
 			 &tls_config->peer_verify,

subsys/net/lib/mqtt/mqtt_transport_socks.c

@@ -1,47 +0,0 @@
-/*
- * Copyright (c) 2019 Antmicro Ltd
- *
- * SPDX-License-Identifier: Apache-2.0
- */
-
-/** @file mqtt_transport_socks.c
- *
- * @brief Internal functions to handle transport over SOCKS5 proxy.
- */
-
-#include <logging/log.h>
-LOG_MODULE_REGISTER(net_mqtt_socks, CONFIG_MQTT_LOG_LEVEL);
-
-#include <errno.h>
-#include <net/socket.h>
-#include <net/socks.h>
-#include <net/mqtt.h>
-
-#include "mqtt_os.h"
-
-/**@brief Handles connect request for TCP socket transport.
- *
- * @param[in] client Identifies the client on which the procedure is requested.
- *
- * @retval 0 or an error code indicating reason for failure.
- */
-int mqtt_client_socks5_connect(struct mqtt_client *client)
-{
-	const struct sockaddr *broker = client->broker;
-	const struct sockaddr *proxy =
-		(struct sockaddr *)client->transport.socks5.proxy;
-
-	if (proxy == NULL || broker == NULL) {
-		return -EINVAL;
-	}
-
-	client->transport.socks5.sock =
-		socks5_client_tcp_connect(proxy, broker);
-
-	if (client->transport.socks5.sock < 0) {
-		return client->transport.socks5.sock;
-	}
-
-	MQTT_TRC("Connect completed");
-	return 0;
-}