MQTT
Diff: MQTTAsync.h
- Revision:
- 20:cad3d54d7ecf
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- 21:e918525e529d
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/MQTTAsync.h Mon Apr 28 16:07:51 2014 +0000 @@ -0,0 +1,586 @@ +/******************************************************************************* + * Copyright (c) 2014 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 + *******************************************************************************/ + +#if !defined(MQTTCLIENT_H) +#define MQTTCLIENT_H + +#include "FP.h" +#include "MQTTPacket.h" +#include "stdio.h" + +namespace MQTT +{ + + +enum QoS { QOS0, QOS1, QOS2 }; + + +struct Message +{ + enum QoS qos; + bool retained; + bool dup; + unsigned short id; + void *payload; + size_t payloadlen; +}; + + +class PacketId +{ +public: + PacketId(); + + int getNext(); + +private: + static const int MAX_PACKET_ID = 65535; + int next; +}; + +typedef void (*messageHandler)(Message*); + +typedef struct limits +{ + int MAX_MQTT_PACKET_SIZE; // + int MAX_MESSAGE_HANDLERS; // each subscription requires a message handler + int MAX_CONCURRENT_OPERATIONS; // each command which runs concurrently can have a result handler, when we are in multi-threaded mode + int command_timeout; + + limits() + { + MAX_MQTT_PACKET_SIZE = 100; + MAX_MESSAGE_HANDLERS = 5; + MAX_CONCURRENT_OPERATIONS = 1; // 1 indicates single-threaded mode - set to >1 for multithreaded mode + command_timeout = 30; + } +} Limits; + + +template<class Network, class Timer, class Thread, class Mutex> class Client +{ + +public: + + struct Result + { + /* success or failure result data */ + Client<Network, Timer, Thread, Mutex>* client; + int connack_rc; + }; + + typedef void (*resultHandler)(Result*); + + Client(Network* network, const Limits limits = Limits()); + + int connect(MQTTPacket_connectData* options = 0, resultHandler fn = 0); + + template<class T> + int connect(MQTTPacket_connectData* options = 0, T *item = 0, void(T::*method)(Result *) = 0); // alternative to pass in pointer to member function + + int publish(const char* topic, Message* message, resultHandler rh = 0); + + int subscribe(const char* topicFilter, enum QoS qos, messageHandler mh, resultHandler rh = 0); + + int unsubscribe(const char* topicFilter, resultHandler rh = 0); + + int disconnect(int timeout, resultHandler rh = 0); + + void yield(int timeout); + +private: + + void run(void const *argument); + int cycle(int timeout); + int waitfor(int packet_type, Timer& atimer); + int keepalive(); + int findFreeOperation(); + + int decodePacket(int* value, int timeout); + int readPacket(int timeout); + int sendPacket(int length, int timeout); + int deliverMessage(MQTTString* topic, Message* message); + + Thread* thread; + Network* ipstack; + + Limits limits; + + char* buf; + char* readbuf; + + Timer ping_timer, connect_timer; + unsigned int keepAliveInterval; + bool ping_outstanding; + + PacketId packetid; + + typedef FP<void, Result*> resultHandlerFP; + resultHandlerFP connectHandler; + + typedef FP<void, Message*> messageHandlerFP; + struct MessageHandlers + { + const char* topic; + messageHandlerFP fp; + } *messageHandlers; // Message handlers are indexed by subscription topic + + // how many concurrent operations should we allow? Each one will require a function pointer + struct Operations + { + unsigned short id; + resultHandlerFP fp; + const char* topic; // if this is a publish, store topic name in case republishing is required + Message* message; // for publish, + Timer timer; // to check if the command has timed out + } *operations; // result handlers are indexed by packet ids + + static void threadfn(void* arg); + +}; + +} + + +template<class Network, class Timer, class Thread, class Mutex> void MQTT::Client<Network, Timer, Thread, Mutex>::threadfn(void* arg) +{ + ((Client<Network, Timer, Thread, Mutex>*) arg)->run(NULL); +} + + +template<class Network, class Timer, class Thread, class Mutex> MQTT::Client<Network, Timer, Thread, Mutex>::Client(Network* network, Limits limits) : limits(limits), packetid() +{ + this->thread = 0; + this->ipstack = network; + this->ping_timer = Timer(); + this->ping_outstanding = 0; + + // How to make these memory allocations portable? I was hoping to avoid the heap + buf = new char[limits.MAX_MQTT_PACKET_SIZE]; + readbuf = new char[limits.MAX_MQTT_PACKET_SIZE]; + this->operations = new struct Operations[limits.MAX_CONCURRENT_OPERATIONS]; + for (int i = 0; i < limits.MAX_CONCURRENT_OPERATIONS; ++i) + operations[i].id = 0; + this->messageHandlers = new struct MessageHandlers[limits.MAX_MESSAGE_HANDLERS]; + for (int i = 0; i < limits.MAX_MESSAGE_HANDLERS; ++i) + messageHandlers[i].topic = 0; +} + + +template<class Network, class Timer, class Thread, class Mutex> int MQTT::Client<Network, Timer, Thread, Mutex>::sendPacket(int length, int timeout) +{ + int sent = 0; + + while (sent < length) + sent += ipstack->write(&buf[sent], length, timeout); + if (sent == length) + ping_timer.countdown(this->keepAliveInterval); // record the fact that we have successfully sent the packet + return sent; +} + + +template<class Network, class Timer, class Thread, class Mutex> int MQTT::Client<Network, Timer, Thread, Mutex>::decodePacket(int* value, int timeout) +{ + char c; + int multiplier = 1; + int len = 0; + const int MAX_NO_OF_REMAINING_LENGTH_BYTES = 4; + + *value = 0; + do + { + int rc = MQTTPACKET_READ_ERROR; + + if (++len > MAX_NO_OF_REMAINING_LENGTH_BYTES) + { + rc = MQTTPACKET_READ_ERROR; /* bad data */ + goto exit; + } + rc = ipstack->read(&c, 1, timeout); + if (rc != 1) + goto exit; + *value += (c & 127) * multiplier; + multiplier *= 128; + } while ((c & 128) != 0); +exit: + return len; +} + + +/** + * If any read fails in this method, then we should disconnect from the network, as on reconnect + * the packets can be retried. + * @param timeout the max time to wait for the packet read to complete, in milliseconds + * @return the MQTT packet type, or -1 if none + */ +template<class Network, class Timer, class Thread, class Mutex> int MQTT::Client<Network, Timer, Thread, Mutex>::readPacket(int timeout) +{ + int rc = -1; + MQTTHeader header = {0}; + int len = 0; + int rem_len = 0; + + /* 1. read the header byte. This has the packet type in it */ + if (ipstack->read(readbuf, 1, timeout) != 1) + goto exit; + + len = 1; + /* 2. read the remaining length. This is variable in itself */ + decodePacket(&rem_len, timeout); + len += MQTTPacket_encode(readbuf + 1, rem_len); /* put the original remaining length back into the buffer */ + + /* 3. read the rest of the buffer using a callback to supply the rest of the data */ + if (ipstack->read(readbuf + len, rem_len, timeout) != rem_len) + goto exit; + + header.byte = readbuf[0]; + rc = header.bits.type; +exit: + return rc; +} + + +template<class Network, class Timer, class Thread, class Mutex> int MQTT::Client<Network, Timer, Thread, Mutex>::deliverMessage(MQTTString* topic, Message* message) +{ + int rc = -1; + + // we have to find the right message handler - indexed by topic + for (int i = 0; i < limits.MAX_MESSAGE_HANDLERS; ++i) + { + if (messageHandlers[i].topic != 0 && MQTTPacket_equals(topic, (char*)messageHandlers[i].topic)) + { + messageHandlers[i].fp(message); + rc = 0; + break; + } + } + + return rc; +} + + + +template<class Network, class Timer, class Thread, class Mutex> void MQTT::Client<Network, Timer, Thread, Mutex>::yield(int timeout) +{ + Timer atimer = Timer(); + + atimer.countdown_ms(timeout); + while (!atimer.expired()) + cycle(atimer.left_ms()); +} + + +template<class Network, class Timer, class Thread, class Mutex> int MQTT::Client<Network, Timer, Thread, Mutex>::cycle(int timeout) +{ + /* get one piece of work off the wire and one pass through */ + + // read the socket, see what work is due + int packet_type = readPacket(timeout); + + int len, rc; + switch (packet_type) + { + case CONNACK: + if (this->thread) + { + Result res = {this, 0}; + if (MQTTDeserialize_connack(&res.connack_rc, readbuf, limits.MAX_MQTT_PACKET_SIZE) == 1) + ; + connectHandler(&res); + connectHandler.detach(); // only invoke the callback once + } + break; + case PUBACK: + if (this->thread) + ; //call resultHandler + case SUBACK: + break; + case PUBLISH: + MQTTString topicName; + Message msg; + rc = MQTTDeserialize_publish((int*)&msg.dup, (int*)&msg.qos, (int*)&msg.retained, (int*)&msg.id, &topicName, + (char**)&msg.payload, (int*)&msg.payloadlen, readbuf, limits.MAX_MQTT_PACKET_SIZE);; + if (msg.qos == QOS0) + deliverMessage(&topicName, &msg); + break; + case PUBREC: + int type, dup, mypacketid; + if (MQTTDeserialize_ack(&type, &dup, &mypacketid, readbuf, limits.MAX_MQTT_PACKET_SIZE) == 1) + ; + // must lock this access against the application thread, if we are multi-threaded + len = MQTTSerialize_ack(buf, limits.MAX_MQTT_PACKET_SIZE, PUBREL, 0, mypacketid); + rc = sendPacket(len, timeout); // send the PUBREL packet + if (rc != len) + goto exit; // there was a problem + + break; + case PUBCOMP: + break; + case PINGRESP: + ping_outstanding = false; + break; + } + keepalive(); +exit: + return packet_type; +} + + +template<class Network, class Timer, class Thread, class Mutex> int MQTT::Client<Network, Timer, Thread, Mutex>::keepalive() +{ + int rc = 0; + + if (keepAliveInterval == 0) + goto exit; + + if (ping_timer.expired()) + { + if (ping_outstanding) + rc = -1; + else + { + int len = MQTTSerialize_pingreq(buf, limits.MAX_MQTT_PACKET_SIZE); + rc = sendPacket(len, 1000); // send the ping packet + if (rc != len) + rc = -1; // indicate there's a problem + else + ping_outstanding = true; + } + } + +exit: + return rc; +} + + +template<class Network, class Timer, class Thread, class Mutex> void MQTT::Client<Network, Timer, Thread, Mutex>::run(void const *argument) +{ + while (true) + cycle(ping_timer.left_ms()); +} + + +// only used in single-threaded mode where one command at a time is in process +template<class Network, class Timer, class Thread, class Mutex> int MQTT::Client<Network, Timer, Thread, Mutex>::waitfor(int packet_type, Timer& atimer) +{ + int rc = -1; + + do + { + if (atimer.expired()) + break; // we timed out + } + while ((rc = cycle(atimer.left_ms())) != packet_type); + + return rc; +} + + +template<class Network, class Timer, class Thread, class Mutex> int MQTT::Client<Network, Timer, Thread, Mutex>::connect(MQTTPacket_connectData* options, resultHandler resultHandler) +{ + connect_timer.countdown(limits.command_timeout); + + MQTTPacket_connectData default_options = MQTTPacket_connectData_initializer; + if (options == 0) + options = &default_options; // set default options if none were supplied + + this->keepAliveInterval = options->keepAliveInterval; + ping_timer.countdown(this->keepAliveInterval); + int len = MQTTSerialize_connect(buf, limits.MAX_MQTT_PACKET_SIZE, options); + int rc = sendPacket(len, connect_timer.left_ms()); // send the connect packet + if (rc != len) + goto exit; // there was a problem + + if (resultHandler == 0) // wait until the connack is received + { + // this will be a blocking call, wait for the connack + if (waitfor(CONNACK, connect_timer) == CONNACK) + { + int connack_rc = -1; + if (MQTTDeserialize_connack(&connack_rc, readbuf, limits.MAX_MQTT_PACKET_SIZE) == 1) + rc = connack_rc; + } + } + else + { + // set connect response callback function + connectHandler.attach(resultHandler); + + // start background thread + this->thread = new Thread((void (*)(void const *argument))&MQTT::Client<Network, Timer, Thread, Mutex>::threadfn, (void*)this); + } + +exit: + return rc; +} + + +template<class Network, class Timer, class Thread, class Mutex> int MQTT::Client<Network, Timer, Thread, Mutex>::findFreeOperation() +{ + int found = -1; + for (int i = 0; i < limits.MAX_CONCURRENT_OPERATIONS; ++i) + { + if (operations[i].id == 0) + { + found = i; + break; + } + } + return found; +} + + +template<class Network, class Timer, class Thread, class Mutex> int MQTT::Client<Network, Timer, Thread, Mutex>::subscribe(const char* topicFilter, enum QoS qos, messageHandler messageHandler, resultHandler resultHandler) +{ + int index = 0; + if (this->thread) + index = findFreeOperation(); + Timer& atimer = operations[index].timer; + + atimer.countdown(limits.command_timeout); + MQTTString topic = {(char*)topicFilter, 0, 0}; + + int len = MQTTSerialize_subscribe(buf, limits.MAX_MQTT_PACKET_SIZE, 0, packetid.getNext(), 1, &topic, (int*)&qos); + int rc = sendPacket(len, atimer.left_ms()); // send the subscribe packet + if (rc != len) + goto exit; // there was a problem + + /* wait for suback */ + if (resultHandler == 0) + { + // this will block + if (waitfor(SUBACK, atimer) == SUBACK) + { + int count = 0, grantedQoS = -1, mypacketid; + if (MQTTDeserialize_suback(&mypacketid, 1, &count, &grantedQoS, readbuf, limits.MAX_MQTT_PACKET_SIZE) == 1) + rc = grantedQoS; // 0, 1, 2 or 0x80 + if (rc != 0x80) + { + for (int i = 0; i < limits.MAX_MESSAGE_HANDLERS; ++i) + { + if (messageHandlers[i].topic == 0) + { + messageHandlers[i].topic = topicFilter; + messageHandlers[i].fp.attach(messageHandler); + rc = 0; + break; + } + } + } + } + } + else + { + // set subscribe response callback function + + } + +exit: + return rc; +} + + +template<class Network, class Timer, class Thread, class Mutex> int MQTT::Client<Network, Timer, Thread, Mutex>::unsubscribe(const char* topicFilter, resultHandler resultHandler) +{ + int index = 0; + if (this->thread) + index = findFreeOperation(); + Timer& atimer = operations[index].timer; + + atimer.countdown(limits.command_timeout); + MQTTString topic = {(char*)topicFilter, 0, 0}; + + int len = MQTTSerialize_unsubscribe(buf, limits.MAX_MQTT_PACKET_SIZE, 0, packetid.getNext(), 1, &topic); + int rc = sendPacket(len, atimer.left_ms()); // send the subscribe packet + if (rc != len) + goto exit; // there was a problem + + /* wait for unsuback */ + if (resultHandler == 0) + { + // this will block + if (waitfor(UNSUBACK) == UNSUBACK) + { + int mypacketid; + if (MQTTDeserialize_unsuback(&mypacketid, readbuf, limits.MAX_MQTT_PACKET_SIZE) == 1) + rc = 0; + } + } + else + { + // set unsubscribe response callback function + + } + +exit: + return rc; +} + + + +template<class Network, class Timer, class Thread, class Mutex> int MQTT::Client<Network, Timer, Thread, Mutex>::publish(const char* topicName, Message* message, resultHandler resultHandler) +{ + int index = 0; + if (this->thread) + index = findFreeOperation(); + Timer& atimer = operations[index].timer; + + atimer.countdown(limits.command_timeout); + MQTTString topic = {(char*)topicName, 0, 0}; + + if (message->qos == QOS1 || message->qos == QOS2) + message->id = packetid.getNext(); + + int len = MQTTSerialize_publish(buf, limits.MAX_MQTT_PACKET_SIZE, 0, message->qos, message->retained, message->id, topic, (char*)message->payload, message->payloadlen); + int rc = sendPacket(len, atimer.left_ms()); // send the subscribe packet + if (rc != len) + goto exit; // there was a problem + + /* wait for acks */ + if (resultHandler == 0) + { + if (message->qos == QOS1) + { + if (waitfor(PUBACK, atimer) == PUBACK) + { + int type, dup, mypacketid; + if (MQTTDeserialize_ack(&type, &dup, &mypacketid, readbuf, limits.MAX_MQTT_PACKET_SIZE) == 1) + rc = 0; + } + } + else if (message->qos == QOS2) + { + if (waitfor(PUBCOMP, atimer) == PUBCOMP) + { + int type, dup, mypacketid; + if (MQTTDeserialize_ack(&type, &dup, &mypacketid, readbuf, limits.MAX_MQTT_PACKET_SIZE) == 1) + rc = 0; + } + + } + } + else + { + // set publish response callback function + + } + +exit: + return rc; +} + + +#endif