Peng Jing Xuan
MQTT
Diff: MQTTAsync.h
- Revision:
- 20:cad3d54d7ecf
- Child:
- 21:e918525e529d
diff -r 57f6f976e878 -r cad3d54d7ecf MQTTAsync.h
--- /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