| /******************************************************************************* |
| * Copyright (c) 2009, 2017 IBM Corp. |
| * |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v1.0 |
| * and Eclipse Distribution License v1.0 which accompany this distribution. |
| * |
| * The Eclipse Public License is available at |
| * http://www.eclipse.org/legal/epl-v10.html |
| * and the Eclipse Distribution License is available at |
| * http://www.eclipse.org/org/documents/edl-v10.php. |
| * |
| * Contributors: |
| * Ian Craggs - initial API and implementation and/or initial documentation |
| * Ian Craggs, Allan Stockdill-Mander - SSL updates |
| * Ian Craggs - multiple server connection support |
| * Ian Craggs - MQTT 3.1.1 support |
| * Ian Craggs - remove const from eyecatchers #168 |
| *******************************************************************************/ |
| |
| /** |
| * @cond MQTTClient_internal |
| * @mainpage MQTT Client Library Internals |
| * In the beginning there was one MQTT C client library, MQTTClient, as implemented in MQTTClient.c |
| * This library was designed to be easy to use for applications which didn't mind if some of the calls |
| * blocked for a while. For instance, the MQTTClient_connect call will block until a successful |
| * connection has completed, or a connection has failed, which could be as long as the "connection |
| * timeout" interval, whose default is 30 seconds. |
| * |
| * However in mobile devices and other windowing environments, blocking on the GUI thread is a bad |
| * thing as it causes the user interface to freeze. Hence a new API, MQTTAsync, implemented |
| * in MQTTAsync.c, was devised. There are no blocking calls in this library, so it is well suited |
| * to GUI and mobile environments, at the expense of some extra complexity. |
| * |
| * Both libraries are designed to be sparing in the use of threads. So multiple client objects are |
| * handled by one or two threads, with a select call in Socket_getReadySocket(), used to determine |
| * when a socket has incoming data. This API is thread safe: functions may be called by multiple application |
| * threads, with the exception of ::MQTTClient_yield and ::MQTTClient_receive, which are intended |
| * for single threaded environments only. |
| * |
| * @endcond |
| * @cond MQTTClient_main |
| * @mainpage MQTT Client library for C |
| * © Copyright IBM Corp. 2009, 2017 |
| * |
| * @brief An MQTT client library in C. |
| * |
| * These pages describe the original more synchronous API which might be |
| * considered easier to use. Some of the calls will block. For the new |
| * totally asynchronous API where no calls block, which is especially suitable |
| * for use in windowed environments, see the |
| * <a href="../../MQTTAsync/html/index.html">MQTT C Client Asynchronous API Documentation</a>. |
| * The MQTTClient API is not thread safe, whereas the MQTTAsync API is. |
| * |
| * An MQTT client application connects to MQTT-capable servers. |
| * A typical client is responsible for collecting information from a telemetry |
| * device and publishing the information to the server. It can also subscribe |
| * to topics, receive messages, and use this information to control the |
| * telemetry device. |
| * |
| * MQTT clients implement the published MQTT v3 protocol. You can write your own |
| * API to the MQTT protocol using the programming language and platform of your |
| * choice. This can be time-consuming and error-prone. |
| * |
| * To simplify writing MQTT client applications, this library encapsulates |
| * the MQTT v3 protocol for you. Using this library enables a fully functional |
| * MQTT client application to be written in a few lines of code. |
| * The information presented here documents the API provided |
| * by the MQTT Client library for C. |
| * |
| * <b>Using the client</b><br> |
| * Applications that use the client library typically use a similar structure: |
| * <ul> |
| * <li>Create a client object</li> |
| * <li>Set the options to connect to an MQTT server</li> |
| * <li>Set up callback functions if multi-threaded (asynchronous mode) |
| * operation is being used (see @ref async).</li> |
| * <li>Subscribe to any topics the client needs to receive</li> |
| * <li>Repeat until finished:</li> |
| * <ul> |
| * <li>Publish any messages the client needs to</li> |
| * <li>Handle any incoming messages</li> |
| * </ul> |
| * <li>Disconnect the client</li> |
| * <li>Free any memory being used by the client</li> |
| * </ul> |
| * Some simple examples are shown here: |
| * <ul> |
| * <li>@ref pubsync</li> |
| * <li>@ref pubasync</li> |
| * <li>@ref subasync</li> |
| * </ul> |
| * Additional information about important concepts is provided here: |
| * <ul> |
| * <li>@ref async</li> |
| * <li>@ref wildcard</li> |
| * <li>@ref qos</li> |
| * <li>@ref tracing</li> |
| * </ul> |
| * @endcond |
| */ |
| |
| /* |
| /// @cond EXCLUDE |
| */ |
| #if defined(__cplusplus) |
| extern "C" { |
| #endif |
| #if !defined(MQTTCLIENT_H) |
| #define MQTTCLIENT_H |
| |
| #if defined(WIN32) || defined(WIN64) |
| #define DLLImport __declspec(dllimport) |
| #define DLLExport __declspec(dllexport) |
| #else |
| #define DLLImport extern |
| #define DLLExport __attribute__ ((visibility ("default"))) |
| #endif |
| |
| #include <stdio.h> |
| /* |
| /// @endcond |
| */ |
| |
| #if !defined(NO_PERSISTENCE) |
| #include "MQTTClientPersistence.h" |
| #endif |
| |
| /** |
| * Return code: No error. Indicates successful completion of an MQTT client |
| * operation. |
| */ |
| #define MQTTCLIENT_SUCCESS 0 |
| /** |
| * Return code: A generic error code indicating the failure of an MQTT client |
| * operation. |
| */ |
| #define MQTTCLIENT_FAILURE -1 |
| |
| /* error code -2 is MQTTCLIENT_PERSISTENCE_ERROR */ |
| |
| /** |
| * Return code: The client is disconnected. |
| */ |
| #define MQTTCLIENT_DISCONNECTED -3 |
| /** |
| * Return code: The maximum number of messages allowed to be simultaneously |
| * in-flight has been reached. |
| */ |
| #define MQTTCLIENT_MAX_MESSAGES_INFLIGHT -4 |
| /** |
| * Return code: An invalid UTF-8 string has been detected. |
| */ |
| #define MQTTCLIENT_BAD_UTF8_STRING -5 |
| /** |
| * Return code: A NULL parameter has been supplied when this is invalid. |
| */ |
| #define MQTTCLIENT_NULL_PARAMETER -6 |
| /** |
| * Return code: The topic has been truncated (the topic string includes |
| * embedded NULL characters). String functions will not access the full topic. |
| * Use the topic length value to access the full topic. |
| */ |
| #define MQTTCLIENT_TOPICNAME_TRUNCATED -7 |
| /** |
| * Return code: A structure parameter does not have the correct eyecatcher |
| * and version number. |
| */ |
| #define MQTTCLIENT_BAD_STRUCTURE -8 |
| /** |
| * Return code: A QoS value that falls outside of the acceptable range (0,1,2) |
| */ |
| #define MQTTCLIENT_BAD_QOS -9 |
| /** |
| * Return code: Attempting SSL connection using non-SSL version of library |
| */ |
| #define MQTTCLIENT_SSL_NOT_SUPPORTED -10 |
| |
| /** |
| * Default MQTT version to connect with. Use 3.1.1 then fall back to 3.1 |
| */ |
| #define MQTTVERSION_DEFAULT 0 |
| /** |
| * MQTT version to connect with: 3.1 |
| */ |
| #define MQTTVERSION_3_1 3 |
| /** |
| * MQTT version to connect with: 3.1.1 |
| */ |
| #define MQTTVERSION_3_1_1 4 |
| /** |
| * Bad return code from subscribe, as defined in the 3.1.1 specification |
| */ |
| #define MQTT_BAD_SUBSCRIBE 0x80 |
| |
| /** |
| * Initialization options |
| */ |
| typedef struct |
| { |
| /** The eyecatcher for this structure. Must be MQTG. */ |
| char struct_id[4]; |
| /** The version number of this structure. Must be 0 */ |
| int struct_version; |
| /** 1 = we do openssl init, 0 = leave it to the application */ |
| int do_openssl_init; |
| } MQTTClient_init_options; |
| |
| #define MQTTClient_init_options_initializer { {'M', 'Q', 'T', 'G'}, 0, 0 } |
| |
| /** |
| * Global init of mqtt library. Call once on program start to set global behaviour. |
| * do_openssl_init - if mqtt library should initialize OpenSSL (1) or rely on the caller to do it before using the library (0) |
| */ |
| DLLExport void MQTTClient_global_init(MQTTClient_init_options* inits); |
| |
| /** |
| * A handle representing an MQTT client. A valid client handle is available |
| * following a successful call to MQTTClient_create(). |
| */ |
| typedef void* MQTTClient; |
| /** |
| * A value representing an MQTT message. A delivery token is returned to the |
| * client application when a message is published. The token can then be used to |
| * check that the message was successfully delivered to its destination (see |
| * MQTTClient_publish(), |
| * MQTTClient_publishMessage(), |
| * MQTTClient_deliveryComplete(), |
| * MQTTClient_waitForCompletion() and |
| * MQTTClient_getPendingDeliveryTokens()). |
| */ |
| typedef int MQTTClient_deliveryToken; |
| typedef int MQTTClient_token; |
| |
| /** |
| * A structure representing the payload and attributes of an MQTT message. The |
| * message topic is not part of this structure (see MQTTClient_publishMessage(), |
| * MQTTClient_publish(), MQTTClient_receive(), MQTTClient_freeMessage() |
| * and MQTTClient_messageArrived()). |
| */ |
| typedef struct |
| { |
| /** The eyecatcher for this structure. must be MQTM. */ |
| char struct_id[4]; |
| /** The version number of this structure. Must be 0 */ |
| int struct_version; |
| /** The length of the MQTT message payload in bytes. */ |
| int payloadlen; |
| /** A pointer to the payload of the MQTT message. */ |
| void* payload; |
| /** |
| * The quality of service (QoS) assigned to the message. |
| * There are three levels of QoS: |
| * <DL> |
| * <DT><B>QoS0</B></DT> |
| * <DD>Fire and forget - the message may not be delivered</DD> |
| * <DT><B>QoS1</B></DT> |
| * <DD>At least once - the message will be delivered, but may be |
| * delivered more than once in some circumstances.</DD> |
| * <DT><B>QoS2</B></DT> |
| * <DD>Once and one only - the message will be delivered exactly once.</DD> |
| * </DL> |
| */ |
| int qos; |
| /** |
| * The retained flag serves two purposes depending on whether the message |
| * it is associated with is being published or received. |
| * |
| * <b>retained = true</b><br> |
| * For messages being published, a true setting indicates that the MQTT |
| * server should retain a copy of the message. The message will then be |
| * transmitted to new subscribers to a topic that matches the message topic. |
| * For subscribers registering a new subscription, the flag being true |
| * indicates that the received message is not a new one, but one that has |
| * been retained by the MQTT server. |
| * |
| * <b>retained = false</b> <br> |
| * For publishers, this ndicates that this message should not be retained |
| * by the MQTT server. For subscribers, a false setting indicates this is |
| * a normal message, received as a result of it being published to the |
| * server. |
| */ |
| int retained; |
| /** |
| * The dup flag indicates whether or not this message is a duplicate. |
| * It is only meaningful when receiving QoS1 messages. When true, the |
| * client application should take appropriate action to deal with the |
| * duplicate message. |
| */ |
| int dup; |
| /** The message identifier is normally reserved for internal use by the |
| * MQTT client and server. |
| */ |
| int msgid; |
| } MQTTClient_message; |
| |
| #define MQTTClient_message_initializer { {'M', 'Q', 'T', 'M'}, 0, 0, NULL, 0, 0, 0, 0 } |
| |
| /** |
| * This is a callback function. The client application |
| * must provide an implementation of this function to enable asynchronous |
| * receipt of messages. The function is registered with the client library by |
| * passing it as an argument to MQTTClient_setCallbacks(). It is |
| * called by the client library when a new message that matches a client |
| * subscription has been received from the server. This function is executed on |
| * a separate thread to the one on which the client application is running. |
| * @param context A pointer to the <i>context</i> value originally passed to |
| * MQTTClient_setCallbacks(), which contains any application-specific context. |
| * @param topicName The topic associated with the received message. |
| * @param topicLen The length of the topic if there are one |
| * more NULL characters embedded in <i>topicName</i>, otherwise <i>topicLen</i> |
| * is 0. If <i>topicLen</i> is 0, the value returned by <i>strlen(topicName)</i> |
| * can be trusted. If <i>topicLen</i> is greater than 0, the full topic name |
| * can be retrieved by accessing <i>topicName</i> as a byte array of length |
| * <i>topicLen</i>. |
| * @param message The MQTTClient_message structure for the received message. |
| * This structure contains the message payload and attributes. |
| * @return This function must return a boolean value indicating whether or not |
| * the message has been safely received by the client application. Returning |
| * true indicates that the message has been successfully handled. |
| * Returning false indicates that there was a problem. In this |
| * case, the client library will reinvoke MQTTClient_messageArrived() to |
| * attempt to deliver the message to the application again. |
| */ |
| typedef int MQTTClient_messageArrived(void* context, char* topicName, int topicLen, MQTTClient_message* message); |
| |
| /** |
| * This is a callback function. The client application |
| * must provide an implementation of this function to enable asynchronous |
| * notification of delivery of messages. The function is registered with the |
| * client library by passing it as an argument to MQTTClient_setCallbacks(). |
| * It is called by the client library after the client application has |
| * published a message to the server. It indicates that the necessary |
| * handshaking and acknowledgements for the requested quality of service (see |
| * MQTTClient_message.qos) have been completed. This function is executed on a |
| * separate thread to the one on which the client application is running. |
| * <b>Note:</b>MQTTClient_deliveryComplete() is not called when messages are |
| * published at QoS0. |
| * @param context A pointer to the <i>context</i> value originally passed to |
| * MQTTClient_setCallbacks(), which contains any application-specific context. |
| * @param dt The ::MQTTClient_deliveryToken associated with |
| * the published message. Applications can check that all messages have been |
| * correctly published by matching the delivery tokens returned from calls to |
| * MQTTClient_publish() and MQTTClient_publishMessage() with the tokens passed |
| * to this callback. |
| */ |
| typedef void MQTTClient_deliveryComplete(void* context, MQTTClient_deliveryToken dt); |
| |
| /** |
| * This is a callback function. The client application |
| * must provide an implementation of this function to enable asynchronous |
| * notification of the loss of connection to the server. The function is |
| * registered with the client library by passing it as an argument to |
| * MQTTClient_setCallbacks(). It is called by the client library if the client |
| * loses its connection to the server. The client application must take |
| * appropriate action, such as trying to reconnect or reporting the problem. |
| * This function is executed on a separate thread to the one on which the |
| * client application is running. |
| * @param context A pointer to the <i>context</i> value originally passed to |
| * MQTTClient_setCallbacks(), which contains any application-specific context. |
| * @param cause The reason for the disconnection. |
| * Currently, <i>cause</i> is always set to NULL. |
| */ |
| typedef void MQTTClient_connectionLost(void* context, char* cause); |
| |
| /** |
| * This function sets the callback functions for a specific client. |
| * If your client application doesn't use a particular callback, set the |
| * relevant parameter to NULL. Calling MQTTClient_setCallbacks() puts the |
| * client into multi-threaded mode. Any necessary message acknowledgements and |
| * status communications are handled in the background without any intervention |
| * from the client application. See @ref async for more information. |
| * |
| * <b>Note:</b> The MQTT client must be disconnected when this function is |
| * called. |
| * @param handle A valid client handle from a successful call to |
| * MQTTClient_create(). |
| * @param context A pointer to any application-specific context. The |
| * the <i>context</i> pointer is passed to each of the callback functions to |
| * provide access to the context information in the callback. |
| * @param cl A pointer to an MQTTClient_connectionLost() callback |
| * function. You can set this to NULL if your application doesn't handle |
| * disconnections. |
| * @param ma A pointer to an MQTTClient_messageArrived() callback |
| * function. This callback function must be specified when you call |
| * MQTTClient_setCallbacks(). |
| * @param dc A pointer to an MQTTClient_deliveryComplete() callback |
| * function. You can set this to NULL if your application publishes |
| * synchronously or if you do not want to check for successful delivery. |
| * @return ::MQTTCLIENT_SUCCESS if the callbacks were correctly set, |
| * ::MQTTCLIENT_FAILURE if an error occurred. |
| */ |
| DLLExport int MQTTClient_setCallbacks(MQTTClient handle, void* context, MQTTClient_connectionLost* cl, |
| MQTTClient_messageArrived* ma, MQTTClient_deliveryComplete* dc); |
| |
| |
| /** |
| * This function creates an MQTT client ready for connection to the |
| * specified server and using the specified persistent storage (see |
| * MQTTClient_persistence). See also MQTTClient_destroy(). |
| * @param handle A pointer to an ::MQTTClient handle. The handle is |
| * populated with a valid client reference following a successful return from |
| * this function. |
| * @param serverURI A null-terminated string specifying the server to |
| * which the client will connect. It takes the form <i>protocol://host:port</i>. |
| * Currently, <i>protocol</i> must be <i>tcp</i> or <i>ssl</i>. |
| * For <i>host</i>, you can |
| * specify either an IP address or a host name. For instance, to connect to |
| * a server running on the local machines with the default MQTT port, specify |
| * <i>tcp://localhost:1883</i>. |
| * @param clientId The client identifier passed to the server when the |
| * client connects to it. It is a null-terminated UTF-8 encoded string. |
| * @param persistence_type The type of persistence to be used by the client: |
| * <br> |
| * ::MQTTCLIENT_PERSISTENCE_NONE: Use in-memory persistence. If the device or |
| * system on which the client is running fails or is switched off, the current |
| * state of any in-flight messages is lost and some messages may not be |
| * delivered even at QoS1 and QoS2. |
| * <br> |
| * ::MQTTCLIENT_PERSISTENCE_DEFAULT: Use the default (file system-based) |
| * persistence mechanism. Status about in-flight messages is held in persistent |
| * storage and provides some protection against message loss in the case of |
| * unexpected failure. |
| * <br> |
| * ::MQTTCLIENT_PERSISTENCE_USER: Use an application-specific persistence |
| * implementation. Using this type of persistence gives control of the |
| * persistence mechanism to the application. The application has to implement |
| * the MQTTClient_persistence interface. |
| * @param persistence_context If the application uses |
| * ::MQTTCLIENT_PERSISTENCE_NONE persistence, this argument is unused and should |
| * be set to NULL. For ::MQTTCLIENT_PERSISTENCE_DEFAULT persistence, it |
| * should be set to the location of the persistence directory (if set |
| * to NULL, the persistence directory used is the working directory). |
| * Applications that use ::MQTTCLIENT_PERSISTENCE_USER persistence set this |
| * argument to point to a valid MQTTClient_persistence structure. |
| * @return ::MQTTCLIENT_SUCCESS if the client is successfully created, otherwise |
| * an error code is returned. |
| */ |
| DLLExport int MQTTClient_create(MQTTClient* handle, const char* serverURI, const char* clientId, |
| int persistence_type, void* persistence_context); |
| |
| /** |
| * MQTTClient_willOptions defines the MQTT "Last Will and Testament" (LWT) settings for |
| * the client. In the event that a client unexpectedly loses its connection to |
| * the server, the server publishes the LWT message to the LWT topic on |
| * behalf of the client. This allows other clients (subscribed to the LWT topic) |
| * to be made aware that the client has disconnected. To enable the LWT |
| * function for a specific client, a valid pointer to an MQTTClient_willOptions |
| * structure is passed in the MQTTClient_connectOptions structure used in the |
| * MQTTClient_connect() call that connects the client to the server. The pointer |
| * to MQTTClient_willOptions can be set to NULL if the LWT function is not |
| * required. |
| */ |
| typedef struct |
| { |
| /** The eyecatcher for this structure. must be MQTW. */ |
| char struct_id[4]; |
| /** The version number of this structure. Must be 0 or 1 |
| 0 means there is no binary payload option |
| */ |
| int struct_version; |
| /** The LWT topic to which the LWT message will be published. */ |
| const char* topicName; |
| /** The LWT payload in string form. */ |
| const char* message; |
| /** |
| * The retained flag for the LWT message (see MQTTClient_message.retained). |
| */ |
| int retained; |
| /** |
| * The quality of service setting for the LWT message (see |
| * MQTTClient_message.qos and @ref qos). |
| */ |
| int qos; |
| /** The LWT payload in binary form. This is only checked and used if the message option is NULL */ |
| struct |
| { |
| int len; /**< binary payload length */ |
| const void* data; /**< binary payload data */ |
| } payload; |
| } MQTTClient_willOptions; |
| |
| #define MQTTClient_willOptions_initializer { {'M', 'Q', 'T', 'W'}, 1, NULL, NULL, 0, 0, {0, NULL} } |
| |
| #define MQTT_SSL_VERSION_DEFAULT 0 |
| #define MQTT_SSL_VERSION_TLS_1_0 1 |
| #define MQTT_SSL_VERSION_TLS_1_1 2 |
| #define MQTT_SSL_VERSION_TLS_1_2 3 |
| |
| /** |
| * MQTTClient_sslProperties defines the settings to establish an SSL/TLS connection using the |
| * OpenSSL library. It covers the following scenarios: |
| * - Server authentication: The client needs the digital certificate of the server. It is included |
| * in a store containting trusted material (also known as "trust store"). |
| * - Mutual authentication: Both client and server are authenticated during the SSL handshake. In |
| * addition to the digital certificate of the server in a trust store, the client will need its own |
| * digital certificate and the private key used to sign its digital certificate stored in a "key store". |
| * - Anonymous connection: Both client and server do not get authenticated and no credentials are needed |
| * to establish an SSL connection. Note that this scenario is not fully secure since it is subject to |
| * man-in-the-middle attacks. |
| */ |
| typedef struct |
| { |
| /** The eyecatcher for this structure. Must be MQTS */ |
| char struct_id[4]; |
| /** The version number of this structure. Must be 0, or 1 to enable TLS version selection. */ |
| int struct_version; |
| |
| /** The file in PEM format containing the public digital certificates trusted by the client. */ |
| const char* trustStore; |
| |
| /** The file in PEM format containing the public certificate chain of the client. It may also include |
| * the client's private key. |
| */ |
| const char* keyStore; |
| |
| /** If not included in the sslKeyStore, this setting points to the file in PEM format containing |
| * the client's private key. |
| */ |
| const char* privateKey; |
| /** The password to load the client's privateKey if encrypted. */ |
| const char* privateKeyPassword; |
| |
| /** |
| * The list of cipher suites that the client will present to the server during the SSL handshake. For a |
| * full explanation of the cipher list format, please see the OpenSSL on-line documentation: |
| * http://www.openssl.org/docs/apps/ciphers.html#CIPHER_LIST_FORMAT |
| * If this setting is ommitted, its default value will be "ALL", that is, all the cipher suites -excluding |
| * those offering no encryption- will be considered. |
| * This setting can be used to set an SSL anonymous connection ("aNULL" string value, for instance). |
| */ |
| const char* enabledCipherSuites; |
| |
| /** True/False option to enable verification of the server certificate **/ |
| int enableServerCertAuth; |
| |
| /** The SSL/TLS version to use. Specify one of MQTT_SSL_VERSION_DEFAULT (0), |
| * MQTT_SSL_VERSION_TLS_1_0 (1), MQTT_SSL_VERSION_TLS_1_1 (2) or MQTT_SSL_VERSION_TLS_1_2 (3). |
| * Only used if struct_version is >= 1. |
| */ |
| int sslVersion; |
| |
| } MQTTClient_SSLOptions; |
| |
| #define MQTTClient_SSLOptions_initializer { {'M', 'Q', 'T', 'S'}, 1, NULL, NULL, NULL, NULL, NULL, 1, MQTT_SSL_VERSION_DEFAULT } |
| |
| /** |
| * MQTTClient_connectOptions defines several settings that control the way the |
| * client connects to an MQTT server. |
| * |
| * <b>Note:</b> Default values are not defined for members of |
| * MQTTClient_connectOptions so it is good practice to specify all settings. |
| * If the MQTTClient_connectOptions structure is defined as an automatic |
| * variable, all members are set to random values and thus must be set by the |
| * client application. If the MQTTClient_connectOptions structure is defined |
| * as a static variable, initialization (in compliant compilers) sets all |
| * values to 0 (NULL for pointers). A #keepAliveInterval setting of 0 prevents |
| * correct operation of the client and so you <b>must</b> at least set a value |
| * for #keepAliveInterval. |
| */ |
| typedef struct |
| { |
| /** The eyecatcher for this structure. must be MQTC. */ |
| char struct_id[4]; |
| /** The version number of this structure. Must be 0, 1, 2, 3, 4 or 5. |
| * 0 signifies no SSL options and no serverURIs |
| * 1 signifies no serverURIs |
| * 2 signifies no MQTTVersion |
| * 3 signifies no returned values |
| * 4 signifies no binary password option |
| */ |
| int struct_version; |
| /** The "keep alive" interval, measured in seconds, defines the maximum time |
| * that should pass without communication between the client and the server |
| * The client will ensure that at least one message travels across the |
| * network within each keep alive period. In the absence of a data-related |
| * message during the time period, the client sends a very small MQTT |
| * "ping" message, which the server will acknowledge. The keep alive |
| * interval enables the client to detect when the server is no longer |
| * available without having to wait for the long TCP/IP timeout. |
| */ |
| int keepAliveInterval; |
| /** |
| * This is a boolean value. The cleansession setting controls the behaviour |
| * of both the client and the server at connection and disconnection time. |
| * The client and server both maintain session state information. This |
| * information is used to ensure "at least once" and "exactly once" |
| * delivery, and "exactly once" receipt of messages. Session state also |
| * includes subscriptions created by an MQTT client. You can choose to |
| * maintain or discard state information between sessions. |
| * |
| * When cleansession is true, the state information is discarded at |
| * connect and disconnect. Setting cleansession to false keeps the state |
| * information. When you connect an MQTT client application with |
| * MQTTClient_connect(), the client identifies the connection using the |
| * client identifier and the address of the server. The server checks |
| * whether session information for this client |
| * has been saved from a previous connection to the server. If a previous |
| * session still exists, and cleansession=true, then the previous session |
| * information at the client and server is cleared. If cleansession=false, |
| * the previous session is resumed. If no previous session exists, a new |
| * session is started. |
| */ |
| int cleansession; |
| /** |
| * This is a boolean value that controls how many messages can be in-flight |
| * simultaneously. Setting <i>reliable</i> to true means that a published |
| * message must be completed (acknowledgements received) before another |
| * can be sent. Attempts to publish additional messages receive an |
| * ::MQTTCLIENT_MAX_MESSAGES_INFLIGHT return code. Setting this flag to |
| * false allows up to 10 messages to be in-flight. This can increase |
| * overall throughput in some circumstances. |
| */ |
| int reliable; |
| /** |
| * This is a pointer to an MQTTClient_willOptions structure. If your |
| * application does not make use of the Last Will and Testament feature, |
| * set this pointer to NULL. |
| */ |
| MQTTClient_willOptions* will; |
| /** |
| * MQTT servers that support the MQTT v3.1.1 protocol provide authentication |
| * and authorisation by user name and password. This is the user name |
| * parameter. |
| */ |
| const char* username; |
| /** |
| * MQTT servers that support the MQTT v3.1.1 protocol provide authentication |
| * and authorisation by user name and password. This is the password |
| * parameter. |
| */ |
| const char* password; |
| /** |
| * The time interval in seconds to allow a connect to complete. |
| */ |
| int connectTimeout; |
| /** |
| * The time interval in seconds |
| */ |
| int retryInterval; |
| /** |
| * This is a pointer to an MQTTClient_SSLOptions structure. If your |
| * application does not make use of SSL, set this pointer to NULL. |
| */ |
| MQTTClient_SSLOptions* ssl; |
| /** |
| * The number of entries in the optional serverURIs array. Defaults to 0. |
| */ |
| int serverURIcount; |
| /** |
| * An optional array of null-terminated strings specifying the servers to |
| * which the client will connect. Each string takes the form <i>protocol://host:port</i>. |
| * <i>protocol</i> must be <i>tcp</i> or <i>ssl</i>. For <i>host</i>, you can |
| * specify either an IP address or a host name. For instance, to connect to |
| * a server running on the local machines with the default MQTT port, specify |
| * <i>tcp://localhost:1883</i>. |
| * If this list is empty (the default), the server URI specified on MQTTClient_create() |
| * is used. |
| */ |
| char* const* serverURIs; |
| /** |
| * Sets the version of MQTT to be used on the connect. |
| * MQTTVERSION_DEFAULT (0) = default: start with 3.1.1, and if that fails, fall back to 3.1 |
| * MQTTVERSION_3_1 (3) = only try version 3.1 |
| * MQTTVERSION_3_1_1 (4) = only try version 3.1.1 |
| */ |
| int MQTTVersion; |
| /** |
| * Returned from the connect when the MQTT version used to connect is 3.1.1 |
| */ |
| struct |
| { |
| const char* serverURI; /**< the serverURI connected to */ |
| int MQTTVersion; /**< the MQTT version used to connect with */ |
| int sessionPresent; /**< if the MQTT version is 3.1.1, the value of sessionPresent returned in the connack */ |
| } returned; |
| /** |
| * Optional binary password. Only checked and used if the password option is NULL |
| */ |
| struct { |
| int len; /**< binary password length */ |
| const void* data; /**< binary password data */ |
| } binarypwd; |
| } MQTTClient_connectOptions; |
| |
| #define MQTTClient_connectOptions_initializer { {'M', 'Q', 'T', 'C'}, 5, 60, 1, 1, NULL, NULL, NULL, 30, 20, NULL, 0, NULL, 0, {NULL, 0, 0}, {0, NULL} } |
| |
| /** |
| * MQTTClient_libraryInfo is used to store details relating to the currently used |
| * library such as the version in use, the time it was built and relevant openSSL |
| * options. |
| * There is one static instance of this struct in MQTTClient.c |
| */ |
| |
| typedef struct |
| { |
| const char* name; |
| const char* value; |
| } MQTTClient_nameValue; |
| |
| /** |
| * This function returns version information about the library. |
| * no trace information will be returned. |
| * @return an array of strings describing the library. The last entry is a NULL pointer. |
| */ |
| DLLExport MQTTClient_nameValue* MQTTClient_getVersionInfo(void); |
| |
| /** |
| * This function attempts to connect a previously-created client (see |
| * MQTTClient_create()) to an MQTT server using the specified options. If you |
| * want to enable asynchronous message and status notifications, you must call |
| * MQTTClient_setCallbacks() prior to MQTTClient_connect(). |
| * @param handle A valid client handle from a successful call to |
| * MQTTClient_create(). |
| * @param options A pointer to a valid MQTTClient_connectOptions |
| * structure. |
| * @return ::MQTTCLIENT_SUCCESS if the client successfully connects to the |
| * server. An error code is returned if the client was unable to connect to |
| * the server. |
| * Error codes greater than 0 are returned by the MQTT protocol:<br><br> |
| * <b>1</b>: Connection refused: Unacceptable protocol version<br> |
| * <b>2</b>: Connection refused: Identifier rejected<br> |
| * <b>3</b>: Connection refused: Server unavailable<br> |
| * <b>4</b>: Connection refused: Bad user name or password<br> |
| * <b>5</b>: Connection refused: Not authorized<br> |
| * <b>6-255</b>: Reserved for future use<br> |
| */ |
| DLLExport int MQTTClient_connect(MQTTClient handle, MQTTClient_connectOptions* options); |
| |
| /** |
| * This function attempts to disconnect the client from the MQTT |
| * server. In order to allow the client time to complete handling of messages |
| * that are in-flight when this function is called, a timeout period is |
| * specified. When the timeout period has expired, the client disconnects even |
| * if there are still outstanding message acknowledgements. |
| * The next time the client connects to the same server, any QoS 1 or 2 |
| * messages which have not completed will be retried depending on the |
| * cleansession settings for both the previous and the new connection (see |
| * MQTTClient_connectOptions.cleansession and MQTTClient_connect()). |
| * @param handle A valid client handle from a successful call to |
| * MQTTClient_create(). |
| * @param timeout The client delays disconnection for up to this time (in |
| * milliseconds) in order to allow in-flight message transfers to complete. |
| * @return ::MQTTCLIENT_SUCCESS if the client successfully disconnects from |
| * the server. An error code is returned if the client was unable to disconnect |
| * from the server |
| */ |
| DLLExport int MQTTClient_disconnect(MQTTClient handle, int timeout); |
| |
| /** |
| * This function allows the client application to test whether or not a |
| * client is currently connected to the MQTT server. |
| * @param handle A valid client handle from a successful call to |
| * MQTTClient_create(). |
| * @return Boolean true if the client is connected, otherwise false. |
| */ |
| DLLExport int MQTTClient_isConnected(MQTTClient handle); |
| |
| |
| /* Subscribe is synchronous. QoS list parameter is changed on return to granted QoSs. |
| Returns return code, MQTTCLIENT_SUCCESS == success, non-zero some sort of error (TBD) */ |
| |
| /** |
| * This function attempts to subscribe a client to a single topic, which may |
| * contain wildcards (see @ref wildcard). This call also specifies the |
| * @ref qos requested for the subscription |
| * (see also MQTTClient_subscribeMany()). |
| * @param handle A valid client handle from a successful call to |
| * MQTTClient_create(). |
| * @param topic The subscription topic, which may include wildcards. |
| * @param qos The requested quality of service for the subscription. |
| * @return ::MQTTCLIENT_SUCCESS if the subscription request is successful. |
| * An error code is returned if there was a problem registering the |
| * subscription. |
| */ |
| DLLExport int MQTTClient_subscribe(MQTTClient handle, const char* topic, int qos); |
| |
| /** |
| * This function attempts to subscribe a client to a list of topics, which may |
| * contain wildcards (see @ref wildcard). This call also specifies the |
| * @ref qos requested for each topic (see also MQTTClient_subscribe()). |
| * @param handle A valid client handle from a successful call to |
| * MQTTClient_create(). |
| * @param count The number of topics for which the client is requesting |
| * subscriptions. |
| * @param topic An array (of length <i>count</i>) of pointers to |
| * topics, each of which may include wildcards. |
| * @param qos An array (of length <i>count</i>) of @ref qos |
| * values. qos[n] is the requested QoS for topic[n]. |
| * @return ::MQTTCLIENT_SUCCESS if the subscription request is successful. |
| * An error code is returned if there was a problem registering the |
| * subscriptions. |
| */ |
| DLLExport int MQTTClient_subscribeMany(MQTTClient handle, int count, char* const* topic, int* qos); |
| |
| /** |
| * This function attempts to remove an existing subscription made by the |
| * specified client. |
| * @param handle A valid client handle from a successful call to |
| * MQTTClient_create(). |
| * @param topic The topic for the subscription to be removed, which may |
| * include wildcards (see @ref wildcard). |
| * @return ::MQTTCLIENT_SUCCESS if the subscription is removed. |
| * An error code is returned if there was a problem removing the |
| * subscription. |
| */ |
| DLLExport int MQTTClient_unsubscribe(MQTTClient handle, const char* topic); |
| |
| /** |
| * This function attempts to remove existing subscriptions to a list of topics |
| * made by the specified client. |
| * @param handle A valid client handle from a successful call to |
| * MQTTClient_create(). |
| * @param count The number subscriptions to be removed. |
| * @param topic An array (of length <i>count</i>) of pointers to the topics of |
| * the subscriptions to be removed, each of which may include wildcards. |
| * @return ::MQTTCLIENT_SUCCESS if the subscriptions are removed. |
| * An error code is returned if there was a problem removing the subscriptions. |
| */ |
| DLLExport int MQTTClient_unsubscribeMany(MQTTClient handle, int count, char* const* topic); |
| |
| /** |
| * This function attempts to publish a message to a given topic (see also |
| * MQTTClient_publishMessage()). An ::MQTTClient_deliveryToken is issued when |
| * this function returns successfully. If the client application needs to |
| * test for succesful delivery of QoS1 and QoS2 messages, this can be done |
| * either asynchronously or synchronously (see @ref async, |
| * ::MQTTClient_waitForCompletion and MQTTClient_deliveryComplete()). |
| * @param handle A valid client handle from a successful call to |
| * MQTTClient_create(). |
| * @param topicName The topic associated with this message. |
| * @param payloadlen The length of the payload in bytes. |
| * @param payload A pointer to the byte array payload of the message. |
| * @param qos The @ref qos of the message. |
| * @param retained The retained flag for the message. |
| * @param dt A pointer to an ::MQTTClient_deliveryToken. This is populated |
| * with a token representing the message when the function returns |
| * successfully. If your application does not use delivery tokens, set this |
| * argument to NULL. |
| * @return ::MQTTCLIENT_SUCCESS if the message is accepted for publication. |
| * An error code is returned if there was a problem accepting the message. |
| */ |
| DLLExport int MQTTClient_publish(MQTTClient handle, const char* topicName, int payloadlen, void* payload, int qos, int retained, |
| MQTTClient_deliveryToken* dt); |
| /** |
| * This function attempts to publish a message to a given topic (see also |
| * MQTTClient_publish()). An ::MQTTClient_deliveryToken is issued when |
| * this function returns successfully. If the client application needs to |
| * test for succesful delivery of QoS1 and QoS2 messages, this can be done |
| * either asynchronously or synchronously (see @ref async, |
| * ::MQTTClient_waitForCompletion and MQTTClient_deliveryComplete()). |
| * @param handle A valid client handle from a successful call to |
| * MQTTClient_create(). |
| * @param topicName The topic associated with this message. |
| * @param msg A pointer to a valid MQTTClient_message structure containing |
| * the payload and attributes of the message to be published. |
| * @param dt A pointer to an ::MQTTClient_deliveryToken. This is populated |
| * with a token representing the message when the function returns |
| * successfully. If your application does not use delivery tokens, set this |
| * argument to NULL. |
| * @return ::MQTTCLIENT_SUCCESS if the message is accepted for publication. |
| * An error code is returned if there was a problem accepting the message. |
| */ |
| DLLExport int MQTTClient_publishMessage(MQTTClient handle, const char* topicName, MQTTClient_message* msg, MQTTClient_deliveryToken* dt); |
| |
| |
| /** |
| * This function is called by the client application to synchronize execution |
| * of the main thread with completed publication of a message. When called, |
| * MQTTClient_waitForCompletion() blocks execution until the message has been |
| * successful delivered or the specified timeout has expired. See @ref async. |
| * @param handle A valid client handle from a successful call to |
| * MQTTClient_create(). |
| * @param dt The ::MQTTClient_deliveryToken that represents the message being |
| * tested for successful delivery. Delivery tokens are issued by the |
| * publishing functions MQTTClient_publish() and MQTTClient_publishMessage(). |
| * @param timeout The maximum time to wait in milliseconds. |
| * @return ::MQTTCLIENT_SUCCESS if the message was successfully delivered. |
| * An error code is returned if the timeout expires or there was a problem |
| * checking the token. |
| */ |
| DLLExport int MQTTClient_waitForCompletion(MQTTClient handle, MQTTClient_deliveryToken dt, unsigned long timeout); |
| |
| |
| /** |
| * This function sets a pointer to an array of delivery tokens for |
| * messages that are currently in-flight (pending completion). |
| * |
| * <b>Important note:</b> The memory used to hold the array of tokens is |
| * malloc()'d in this function. The client application is responsible for |
| * freeing this memory when it is no longer required. |
| * @param handle A valid client handle from a successful call to |
| * MQTTClient_create(). |
| * @param tokens The address of a pointer to an ::MQTTClient_deliveryToken. |
| * When the function returns successfully, the pointer is set to point to an |
| * array of tokens representing messages pending completion. The last member of |
| * the array is set to -1 to indicate there are no more tokens. If no tokens |
| * are pending, the pointer is set to NULL. |
| * @return ::MQTTCLIENT_SUCCESS if the function returns successfully. |
| * An error code is returned if there was a problem obtaining the list of |
| * pending tokens. |
| */ |
| DLLExport int MQTTClient_getPendingDeliveryTokens(MQTTClient handle, MQTTClient_deliveryToken **tokens); |
| |
| /** |
| * When implementing a single-threaded client, call this function periodically |
| * to allow processing of message retries and to send MQTT keepalive pings. |
| * If the application is calling MQTTClient_receive() regularly, then it is |
| * not necessary to call this function. |
| */ |
| DLLExport void MQTTClient_yield(void); |
| |
| /** |
| * This function performs a synchronous receive of incoming messages. It should |
| * be used only when the client application has not set callback methods to |
| * support asynchronous receipt of messages (see @ref async and |
| * MQTTClient_setCallbacks()). Using this function allows a single-threaded |
| * client subscriber application to be written. When called, this function |
| * blocks until the next message arrives or the specified timeout expires |
| *(see also MQTTClient_yield()). |
| * |
| * <b>Important note:</b> The application must free() the memory allocated |
| * to the topic and the message when processing is complete (see |
| * MQTTClient_freeMessage()). |
| * @param handle A valid client handle from a successful call to |
| * MQTTClient_create(). |
| * @param topicName The address of a pointer to a topic. This function |
| * allocates the memory for the topic and returns it to the application |
| * by setting <i>topicName</i> to point to the topic. |
| * @param topicLen The length of the topic. If the return code from this |
| * function is ::MQTTCLIENT_TOPICNAME_TRUNCATED, the topic contains embedded |
| * NULL characters and the full topic should be retrieved by using |
| * <i>topicLen</i>. |
| * @param message The address of a pointer to the received message. This |
| * function allocates the memory for the message and returns it to the |
| * application by setting <i>message</i> to point to the received message. |
| * The pointer is set to NULL if the timeout expires. |
| * @param timeout The length of time to wait for a message in milliseconds. |
| * @return ::MQTTCLIENT_SUCCESS or ::MQTTCLIENT_TOPICNAME_TRUNCATED if a |
| * message is received. ::MQTTCLIENT_SUCCESS can also indicate that the |
| * timeout expired, in which case <i>message</i> is NULL. An error code is |
| * returned if there was a problem trying to receive a message. |
| */ |
| DLLExport int MQTTClient_receive(MQTTClient handle, char** topicName, int* topicLen, MQTTClient_message** message, |
| unsigned long timeout); |
| |
| /** |
| * This function frees memory allocated to an MQTT message, including the |
| * additional memory allocated to the message payload. The client application |
| * calls this function when the message has been fully processed. <b>Important |
| * note:</b> This function does not free the memory allocated to a message |
| * topic string. It is the responsibility of the client application to free |
| * this memory using the MQTTClient_free() library function. |
| * @param msg The address of a pointer to the ::MQTTClient_message structure |
| * to be freed. |
| */ |
| DLLExport void MQTTClient_freeMessage(MQTTClient_message** msg); |
| |
| /** |
| * This function frees memory allocated by the MQTT C client library, especially the |
| * topic name. This is needed on Windows when the client libary and application |
| * program have been compiled with different versions of the C compiler. It is |
| * thus good policy to always use this function when freeing any MQTT C client- |
| * allocated memory. |
| * @param ptr The pointer to the client library storage to be freed. |
| */ |
| DLLExport void MQTTClient_free(void* ptr); |
| |
| /** |
| * This function frees the memory allocated to an MQTT client (see |
| * MQTTClient_create()). It should be called when the client is no longer |
| * required. |
| * @param handle A pointer to the handle referring to the ::MQTTClient |
| * structure to be freed. |
| */ |
| DLLExport void MQTTClient_destroy(MQTTClient* handle); |
| |
| #endif |
| #ifdef __cplusplus |
| } |
| #endif |
| |
| /** |
| * @cond MQTTClient_main |
| * @page async Asynchronous vs synchronous client applications |
| * The client library supports two modes of operation. These are referred to |
| * as <b>synchronous</b> and <b>asynchronous</b> modes. If your application |
| * calls MQTTClient_setCallbacks(), this puts the client into asynchronous |
| * mode, otherwise it operates in synchronous mode. |
| * |
| * In synchronous mode, the client application runs on a single thread. |
| * Messages are published using the MQTTClient_publish() and |
| * MQTTClient_publishMessage() functions. To determine that a QoS1 or QoS2 |
| * (see @ref qos) message has been successfully delivered, the application |
| * must call the MQTTClient_waitForCompletion() function. An example showing |
| * synchronous publication is shown in @ref pubsync. Receiving messages in |
| * synchronous mode uses the MQTTClient_receive() function. Client applications |
| * must call either MQTTClient_receive() or MQTTClient_yield() relatively |
| * frequently in order to allow processing of acknowledgements and the MQTT |
| * "pings" that keep the network connection to the server alive. |
| * |
| * In asynchronous mode, the client application runs on several threads. The |
| * main program calls functions in the client library to publish and subscribe, |
| * just as for the synchronous mode. Processing of handshaking and maintaining |
| * the network connection is performed in the background, however. |
| * Notifications of status and message reception are provided to the client |
| * application using callbacks registered with the library by the call to |
| * MQTTClient_setCallbacks() (see MQTTClient_messageArrived(), |
| * MQTTClient_connectionLost() and MQTTClient_deliveryComplete()). |
| * This API is not thread safe however - it is not possible to call it from multiple |
| * threads without synchronization. You can use the MQTTAsync API for that. |
| * |
| * @page wildcard Subscription wildcards |
| * Every MQTT message includes a topic that classifies it. MQTT servers use |
| * topics to determine which subscribers should receive messages published to |
| * the server. |
| * |
| * Consider the server receiving messages from several environmental sensors. |
| * Each sensor publishes its measurement data as a message with an associated |
| * topic. Subscribing applications need to know which sensor originally |
| * published each received message. A unique topic is thus used to identify |
| * each sensor and measurement type. Topics such as SENSOR1TEMP, |
| * SENSOR1HUMIDITY, SENSOR2TEMP and so on achieve this but are not very |
| * flexible. If additional sensors are added to the system at a later date, |
| * subscribing applications must be modified to receive them. |
| * |
| * To provide more flexibility, MQTT supports a hierarchical topic namespace. |
| * This allows application designers to organize topics to simplify their |
| * management. Levels in the hierarchy are delimited by the '/' character, |
| * such as SENSOR/1/HUMIDITY. Publishers and subscribers use these |
| * hierarchical topics as already described. |
| * |
| * For subscriptions, two wildcard characters are supported: |
| * <ul> |
| * <li>A '#' character represents a complete sub-tree of the hierarchy and |
| * thus must be the last character in a subscription topic string, such as |
| * SENSOR/#. This will match any topic starting with SENSOR/, such as |
| * SENSOR/1/TEMP and SENSOR/2/HUMIDITY.</li> |
| * <li> A '+' character represents a single level of the hierarchy and is |
| * used between delimiters. For example, SENSOR/+/TEMP will match |
| * SENSOR/1/TEMP and SENSOR/2/TEMP.</li> |
| * </ul> |
| * Publishers are not allowed to use the wildcard characters in their topic |
| * names. |
| * |
| * Deciding on your topic hierarchy is an important step in your system design. |
| * |
| * @page qos Quality of service |
| * The MQTT protocol provides three qualities of service for delivering |
| * messages between clients and servers: "at most once", "at least once" and |
| * "exactly once". |
| * |
| * Quality of service (QoS) is an attribute of an individual message being |
| * published. An application sets the QoS for a specific message by setting the |
| * MQTTClient_message.qos field to the required value. |
| * |
| * A subscribing client can set the maximum quality of service a server uses |
| * to send messages that match the client subscriptions. The |
| * MQTTClient_subscribe() and MQTTClient_subscribeMany() functions set this |
| * maximum. The QoS of a message forwarded to a subscriber thus might be |
| * different to the QoS given to the message by the original publisher. |
| * The lower of the two values is used to forward a message. |
| * |
| * The three levels are: |
| * |
| * <b>QoS0, At most once:</b> The message is delivered at most once, or it |
| * may not be delivered at all. Its delivery across the network is not |
| * acknowledged. The message is not stored. The message could be lost if the |
| * client is disconnected, or if the server fails. QoS0 is the fastest mode of |
| * transfer. It is sometimes called "fire and forget". |
| * |
| * The MQTT protocol does not require servers to forward publications at QoS0 |
| * to a client. If the client is disconnected at the time the server receives |
| * the publication, the publication might be discarded, depending on the |
| * server implementation. |
| * |
| * <b>QoS1, At least once:</b> The message is always delivered at least once. |
| * It might be delivered multiple times if there is a failure before an |
| * acknowledgment is received by the sender. The message must be stored |
| * locally at the sender, until the sender receives confirmation that the |
| * message has been published by the receiver. The message is stored in case |
| * the message must be sent again. |
| * |
| * <b>QoS2, Exactly once:</b> The message is always delivered exactly once. |
| * The message must be stored locally at the sender, until the sender receives |
| * confirmation that the message has been published by the receiver. The |
| * message is stored in case the message must be sent again. QoS2 is the |
| * safest, but slowest mode of transfer. A more sophisticated handshaking |
| * and acknowledgement sequence is used than for QoS1 to ensure no duplication |
| * of messages occurs. |
| * @page pubsync Synchronous publication example |
| @code |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include "MQTTClient.h" |
| |
| #define ADDRESS "tcp://localhost:1883" |
| #define CLIENTID "ExampleClientPub" |
| #define TOPIC "MQTT Examples" |
| #define PAYLOAD "Hello World!" |
| #define QOS 1 |
| #define TIMEOUT 10000L |
| |
| int main(int argc, char* argv[]) |
| { |
| MQTTClient client; |
| MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer; |
| MQTTClient_message pubmsg = MQTTClient_message_initializer; |
| MQTTClient_deliveryToken token; |
| int rc; |
| |
| MQTTClient_create(&client, ADDRESS, CLIENTID, |
| MQTTCLIENT_PERSISTENCE_NONE, NULL); |
| conn_opts.keepAliveInterval = 20; |
| conn_opts.cleansession = 1; |
| |
| if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS) |
| { |
| printf("Failed to connect, return code %d\n", rc); |
| exit(EXIT_FAILURE); |
| } |
| pubmsg.payload = PAYLOAD; |
| pubmsg.payloadlen = strlen(PAYLOAD); |
| pubmsg.qos = QOS; |
| pubmsg.retained = 0; |
| MQTTClient_publishMessage(client, TOPIC, &pubmsg, &token); |
| printf("Waiting for up to %d seconds for publication of %s\n" |
| "on topic %s for client with ClientID: %s\n", |
| (int)(TIMEOUT/1000), PAYLOAD, TOPIC, CLIENTID); |
| rc = MQTTClient_waitForCompletion(client, token, TIMEOUT); |
| printf("Message with delivery token %d delivered\n", token); |
| MQTTClient_disconnect(client, 10000); |
| MQTTClient_destroy(&client); |
| return rc; |
| } |
| |
| * @endcode |
| * |
| * @page pubasync Asynchronous publication example |
| @code{.c} |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include "MQTTClient.h" |
| |
| #define ADDRESS "tcp://localhost:1883" |
| #define CLIENTID "ExampleClientPub" |
| #define TOPIC "MQTT Examples" |
| #define PAYLOAD "Hello World!" |
| #define QOS 1 |
| #define TIMEOUT 10000L |
| |
| volatile MQTTClient_deliveryToken deliveredtoken; |
| |
| void delivered(void *context, MQTTClient_deliveryToken dt) |
| { |
| printf("Message with token value %d delivery confirmed\n", dt); |
| deliveredtoken = dt; |
| } |
| |
| int msgarrvd(void *context, char *topicName, int topicLen, MQTTClient_message *message) |
| { |
| int i; |
| char* payloadptr; |
| |
| printf("Message arrived\n"); |
| printf(" topic: %s\n", topicName); |
| printf(" message: "); |
| |
| payloadptr = message->payload; |
| for(i=0; i<message->payloadlen; i++) |
| { |
| putchar(*payloadptr++); |
| } |
| putchar('\n'); |
| MQTTClient_freeMessage(&message); |
| MQTTClient_free(topicName); |
| return 1; |
| } |
| |
| void connlost(void *context, char *cause) |
| { |
| printf("\nConnection lost\n"); |
| printf(" cause: %s\n", cause); |
| } |
| |
| int main(int argc, char* argv[]) |
| { |
| MQTTClient client; |
| MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer; |
| MQTTClient_message pubmsg = MQTTClient_message_initializer; |
| MQTTClient_deliveryToken token; |
| int rc; |
| |
| MQTTClient_create(&client, ADDRESS, CLIENTID, |
| MQTTCLIENT_PERSISTENCE_NONE, NULL); |
| conn_opts.keepAliveInterval = 20; |
| conn_opts.cleansession = 1; |
| |
| MQTTClient_setCallbacks(client, NULL, connlost, msgarrvd, delivered); |
| |
| if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS) |
| { |
| printf("Failed to connect, return code %d\n", rc); |
| exit(EXIT_FAILURE); |
| } |
| pubmsg.payload = PAYLOAD; |
| pubmsg.payloadlen = strlen(PAYLOAD); |
| pubmsg.qos = QOS; |
| pubmsg.retained = 0; |
| deliveredtoken = 0; |
| MQTTClient_publishMessage(client, TOPIC, &pubmsg, &token); |
| printf("Waiting for publication of %s\n" |
| "on topic %s for client with ClientID: %s\n", |
| PAYLOAD, TOPIC, CLIENTID); |
| while(deliveredtoken != token); |
| MQTTClient_disconnect(client, 10000); |
| MQTTClient_destroy(&client); |
| return rc; |
| } |
| |
| * @endcode |
| * @page subasync Asynchronous subscription example |
| @code |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include "MQTTClient.h" |
| |
| #define ADDRESS "tcp://localhost:1883" |
| #define CLIENTID "ExampleClientSub" |
| #define TOPIC "MQTT Examples" |
| #define PAYLOAD "Hello World!" |
| #define QOS 1 |
| #define TIMEOUT 10000L |
| |
| volatile MQTTClient_deliveryToken deliveredtoken; |
| |
| void delivered(void *context, MQTTClient_deliveryToken dt) |
| { |
| printf("Message with token value %d delivery confirmed\n", dt); |
| deliveredtoken = dt; |
| } |
| |
| int msgarrvd(void *context, char *topicName, int topicLen, MQTTClient_message *message) |
| { |
| int i; |
| char* payloadptr; |
| |
| printf("Message arrived\n"); |
| printf(" topic: %s\n", topicName); |
| printf(" message: "); |
| |
| payloadptr = message->payload; |
| for(i=0; i<message->payloadlen; i++) |
| { |
| putchar(*payloadptr++); |
| } |
| putchar('\n'); |
| MQTTClient_freeMessage(&message); |
| MQTTClient_free(topicName); |
| return 1; |
| } |
| |
| void connlost(void *context, char *cause) |
| { |
| printf("\nConnection lost\n"); |
| printf(" cause: %s\n", cause); |
| } |
| |
| int main(int argc, char* argv[]) |
| { |
| MQTTClient client; |
| MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer; |
| int rc; |
| int ch; |
| |
| MQTTClient_create(&client, ADDRESS, CLIENTID, |
| MQTTCLIENT_PERSISTENCE_NONE, NULL); |
| conn_opts.keepAliveInterval = 20; |
| conn_opts.cleansession = 1; |
| |
| MQTTClient_setCallbacks(client, NULL, connlost, msgarrvd, delivered); |
| |
| if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS) |
| { |
| printf("Failed to connect, return code %d\n", rc); |
| exit(EXIT_FAILURE); |
| } |
| printf("Subscribing to topic %s\nfor client %s using QoS%d\n\n" |
| "Press Q<Enter> to quit\n\n", TOPIC, CLIENTID, QOS); |
| MQTTClient_subscribe(client, TOPIC, QOS); |
| |
| do |
| { |
| ch = getchar(); |
| } while(ch!='Q' && ch != 'q'); |
| |
| MQTTClient_disconnect(client, 10000); |
| MQTTClient_destroy(&client); |
| return rc; |
| } |
| |
| * @endcode |
| * @page tracing Tracing |
| * |
| * Runtime tracing is controlled by environment variables. |
| * |
| * Tracing is switched on by setting MQTT_C_CLIENT_TRACE. A value of ON, or stdout, prints to |
| * stdout, any other value is interpreted as a file name to use. |
| * |
| * The amount of trace detail is controlled with the MQTT_C_CLIENT_TRACE_LEVEL environment |
| * variable - valid values are ERROR, PROTOCOL, MINIMUM, MEDIUM and MAXIMUM |
| * (from least to most verbose). |
| * |
| * The variable MQTT_C_CLIENT_TRACE_MAX_LINES limits the number of lines of trace that are output |
| * to a file. Two files are used at most, when they are full, the last one is overwritten with the |
| * new trace entries. The default size is 1000 lines. |
| * |
| * ### MQTT Packet Tracing |
| * |
| * A feature that can be very useful is printing the MQTT packets that are sent and received. To |
| * achieve this, use the following environment variable settings: |
| * @code |
| MQTT_C_CLIENT_TRACE=ON |
| MQTT_C_CLIENT_TRACE_LEVEL=PROTOCOL |
| * @endcode |
| * The output you should see looks like this: |
| * @code |
| 20130528 155936.813 3 stdout-subscriber -> CONNECT cleansession: 1 (0) |
| 20130528 155936.813 3 stdout-subscriber <- CONNACK rc: 0 |
| 20130528 155936.813 3 stdout-subscriber -> SUBSCRIBE msgid: 1 (0) |
| 20130528 155936.813 3 stdout-subscriber <- SUBACK msgid: 1 |
| 20130528 155941.818 3 stdout-subscriber -> DISCONNECT (0) |
| * @endcode |
| * where the fields are: |
| * 1. date |
| * 2. time |
| * 3. socket number |
| * 4. client id |
| * 5. direction (-> from client to server, <- from server to client) |
| * 6. packet details |
| * |
| * ### Default Level Tracing |
| * |
| * This is an extract of a default level trace of a call to connect: |
| * @code |
| 19700101 010000.000 (1152206656) (0)> MQTTClient_connect:893 |
| 19700101 010000.000 (1152206656) (1)> MQTTClient_connectURI:716 |
| 20130528 160447.479 Connecting to serverURI localhost:1883 |
| 20130528 160447.479 (1152206656) (2)> MQTTProtocol_connect:98 |
| 20130528 160447.479 (1152206656) (3)> MQTTProtocol_addressPort:48 |
| 20130528 160447.479 (1152206656) (3)< MQTTProtocol_addressPort:73 |
| 20130528 160447.479 (1152206656) (3)> Socket_new:599 |
| 20130528 160447.479 New socket 4 for localhost, port 1883 |
| 20130528 160447.479 (1152206656) (4)> Socket_addSocket:163 |
| 20130528 160447.479 (1152206656) (5)> Socket_setnonblocking:73 |
| 20130528 160447.479 (1152206656) (5)< Socket_setnonblocking:78 (0) |
| 20130528 160447.479 (1152206656) (4)< Socket_addSocket:176 (0) |
| 20130528 160447.479 (1152206656) (4)> Socket_error:95 |
| 20130528 160447.479 (1152206656) (4)< Socket_error:104 (115) |
| 20130528 160447.479 Connect pending |
| 20130528 160447.479 (1152206656) (3)< Socket_new:683 (115) |
| 20130528 160447.479 (1152206656) (2)< MQTTProtocol_connect:131 (115) |
| * @endcode |
| * where the fields are: |
| * 1. date |
| * 2. time |
| * 3. thread id |
| * 4. function nesting level |
| * 5. function entry (>) or exit (<) |
| * 6. function name : line of source code file |
| * 7. return value (if there is one) |
| * |
| * ### Memory Allocation Tracing |
| * |
| * Setting the trace level to maximum causes memory allocations and frees to be traced along with |
| * the default trace entries, with messages like the following: |
| * @code |
| 20130528 161819.657 Allocating 16 bytes in heap at file /home/icraggs/workspaces/mqrtc/mqttv3c/src/MQTTPacket.c line 177 ptr 0x179f930 |
| |
| 20130528 161819.657 Freeing 16 bytes in heap at file /home/icraggs/workspaces/mqrtc/mqttv3c/src/MQTTPacket.c line 201, heap use now 896 bytes |
| * @endcode |
| * When the last MQTT client object is destroyed, if the trace is being recorded |
| * and all memory allocated by the client library has not been freed, an error message will be |
| * written to the trace. This can help with fixing memory leaks. The message will look like this: |
| * @code |
| 20130528 163909.208 Some memory not freed at shutdown, possible memory leak |
| 20130528 163909.208 Heap scan start, total 880 bytes |
| 20130528 163909.208 Heap element size 32, line 354, file /home/icraggs/workspaces/mqrtc/mqttv3c/src/MQTTPacket.c, ptr 0x260cb00 |
| 20130528 163909.208 Content |
| 20130528 163909.209 Heap scan end |
| * @endcode |
| * @endcond |
| */ |