Diff: MQTTSingle.h

Revision:

16:91c2f9a144d4

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MQTTSingle.h	Mon Apr 14 18:51:52 2014 +0000
@@ -0,0 +1,428 @@
+/*******************************************************************************
+ * 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(MQTTSINGLE_H)
+#define MQTTSINGLE_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 command_timeout;
+        
+    limits()
+    {
+        MAX_MQTT_PACKET_SIZE = 100;
+        MAX_MESSAGE_HANDLERS = 5;
+        command_timeout = 30;
+    }
+} Limits;
+  
+  
+template<class Network, class Timer> class Client
+{
+    
+public:    
+ 
+    Client(Network* network, Limits* limits = 0);
+       
+    int connect(MQTTPacket_connectData* options = 0);
+        
+    int publish(const char* topic, Message* message);
+    
+    int subscribe(const char* topicFilter, enum QoS qos, messageHandler mh);
+    
+    int unsubscribe(const char* topicFilter);
+    
+    int disconnect(int timeout);
+    
+private:
+
+    int cycle(int timeout);
+    int keepalive();
+
+    int decodePacket(int* value, int timeout);
+    int readPacket(int timeout = -1);
+    int sendPacket(int length, int timeout = -1);
+    int deliverMessage(MQTTString* topic, Message* message);
+    
+    Network* ipstack;
+    Timer command_timer, ping_timer;
+    
+    char* buf;
+    int buflen;
+    
+    char* readbuf;
+    int readbuflen;
+
+    unsigned int keepAliveInterval;
+    bool ping_outstanding;
+    
+    int command_timeout; // max time to wait for any MQTT command to complete, in seconds
+    PacketId packetid;
+    
+    typedef FP<void, Message*> messageHandlerFP;
+    struct MessageHandlers
+    {
+        char* topic;
+        messageHandlerFP fp;
+    } *messageHandlers;  // Message handlers are linked to a subscription topic
+    int messageHandlerCount;
+    
+};
+
+}
+
+template<class Network, class Timer, class Thread, class Mutex> MQTT::Client<Network, Timer, Thread, Mutex>::Client(Network* network, Limits* limits)  : packetid()
+{
+    Limits default_limits = Limits();
+   
+    if (limits == 0)
+        limits = &default_limits;
+   
+    this->command_timeout = limits->command_timeout;
+    this->ipstack = network;
+    this->command_timer = Timer();
+    this->ping_timer = Timer();
+    this->ping_outstanding = 0;
+       
+    // How to make these memory allocations portable?  I was hoping to avoid the heap
+    buflen = readbuflen = limits->MAX_MQTT_PACKET_SIZE;
+    buf = new char[limits->MAX_MQTT_PACKET_SIZE];
+    readbuf = new char[limits->MAX_MQTT_PACKET_SIZE];
+    this->messageHandlers = new struct MessageHandlers[limits->MAX_MESSAGE_HANDLERS];
+}
+
+
+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, -1);
+    if (sent == length)
+        ping_timer.reset(); // 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)
+{
+    // we have to find the right message handler - indexed by topic
+}
+
+
+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:
+        case PUBACK:
+        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, readbuflen);
+            if (msg.qos == QOS0)
+                deliverMessage(&topicName, &msg);
+            break;
+        case PUBREC:
+            int type, dup, mypacketid;
+            if (MQTTDeserialize_ack(&type, &dup, &mypacketid, readbuf, readbuflen) == 1)
+                ; 
+            // must lock this access against the application thread, if we are multi-threaded
+            len = MQTTSerialize_ack(buf, buflen, PUBREL, 0, mypacketid);
+            rc = sendPacket(len); // send the subscribe 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.read_ms() >= (keepAliveInterval * 1000))
+    {
+        if (ping_outstanding)
+            rc = -1;
+        else
+        {
+            int len = MQTTSerialize_pingreq(buf, buflen);
+            rc = sendPacket(len); // send the connect 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> int MQTT::Client<Network, Timer, Thread, Mutex>::connect(MQTTPacket_connectData* options, resultHandler resultHandler)
+{
+    command_timer.start();
+
+    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.start();
+    int len = MQTTSerialize_connect(buf, buflen, options);
+    int rc = sendPacket(len); // send the connect packet
+    if (rc != len) 
+        goto exit; // there was a problem
+    
+    // this will be a blocking call, wait for the connack
+    do
+    {
+        if (command_timer.read_ms() > (command_timeout * 1000)) 
+             goto exit; // we timed out
+    }
+    while (cycle(command_timeout - command_timer.read_ms()) != CONNACK);
+    int connack_rc = -1;
+    if (MQTTDeserialize_connack(&connack_rc, readbuf, readbuflen) == 1)
+        rc = connack_rc;
+    
+exit:
+    command_timer.stop();
+    command_timer.reset();
+    return rc;
+}
+
+
+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)
+{
+    command_timer.start();
+
+    MQTTString topic = {(char*)topicFilter, 0, 0};
+    
+    int len = MQTTSerialize_subscribe(buf, buflen, 0, packetid.getNext(), 1, &topic, (int*)&qos);
+    int rc = sendPacket(len); // send the subscribe packet
+    if (rc != len) 
+        goto exit; // there was a problem
+    
+    // wait for suback - this will block
+    if (cycle(command_timeout - command_timer.read_ms()) == SUBACK)
+    {
+        int count = 0, grantedQoS = -1, mypacketid;
+        if (MQTTDeserialize_suback(&mypacketid, 1, &count, &grantedQoS, readbuf, readbuflen) == 1)
+            rc = grantedQoS; // 0, 1, 2 or 0x80 
+        if (rc != 0x80)
+    }
+
+exit:
+    command_timer.stop();
+    command_timer.reset();
+    return rc;
+}
+
+
+template<class Network, class Timer, class Thread, class Mutex> int MQTT::Client<Network, Timer, Thread, Mutex>::unsubscribe(const char* topicFilter, resultHandler resultHandler)
+{
+    command_timer.start();
+
+    MQTTString topic = {(char*)topicFilter, 0, 0};
+    
+    int len = MQTTSerialize_unsubscribe(buf, buflen, 0, packetid.getNext(), 1, &topic);
+    int rc = sendPacket(len); // send the subscribe packet
+    if (rc != len) 
+        goto exit; // there was a problem
+    
+    // this will block
+    if (cycle(command_timeout - command_timer.read_ms()) == UNSUBACK)
+    {
+        int mypacketid;
+        if (MQTTDeserialize_unsuback(&mypacketid, readbuf, readbuflen) == 1)
+            rc = 0; 
+    }
+    
+exit:
+    command_timer.stop();
+    command_timer.reset();
+    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)
+{
+    command_timer.start();
+
+    MQTTString topic = {(char*)topicName, 0, 0};
+
+    message->id = packetid.getNext();
+    
+    int len = MQTTSerialize_publish(buf, buflen, 0, message->qos, message->retained, message->id, topic, message->payload, message->payloadlen);
+    int rc = sendPacket(len); // send the subscribe packet
+    if (rc != len) 
+        goto exit; // there was a problem
+    
+    /* wait for acks */
+    if (resultHandler == 0)
+    {
+        if (message->qos == QOS1)
+        {
+            if (cycle(command_timeout - command_timer.read_ms()) == PUBACK)
+            {
+                int type, dup, mypacketid;
+                if (MQTTDeserialize_ack(&type, &dup, &mypacketid, readbuf, readbuflen) == 1)
+                    rc = 0; 
+            }
+        }
+        else if (message->qos == QOS2)
+        {
+            if (cycle(command_timeout - command_timer.read_ms()) == PUBCOMP)
+            {
+                int type, dup, mypacketid;
+                if (MQTTDeserialize_ack(&type, &dup, &mypacketid, readbuf, readbuflen) == 1)
+                    rc = 0; 
+            }
+
+        }
+    }
+    
+exit:
+    command_timer.stop();
+    command_timer.reset();
+    return rc;
+}
+
+
+#endif