MQTTConnectServer.c

00001 /*******************************************************************************
00002  * Copyright (c) 2014 IBM Corp.
00003  *
00004  * All rights reserved. This program and the accompanying materials
00005  * are made available under the terms of the Eclipse Public License v1.0
00006  * and Eclipse Distribution License v1.0 which accompany this distribution.
00007  *
00008  * The Eclipse Public License is available at
00009  *    http://www.eclipse.org/legal/epl-v10.html
00010  * and the Eclipse Distribution License is available at
00011  *   http://www.eclipse.org/org/documents/edl-v10.php.
00012  *
00013  * Contributors:
00014  *    Ian Craggs - initial API and implementation and/or initial documentation
00015  *******************************************************************************/
00016 
00017 #include "StackTrace.h"
00018 #include "MQTTPacket.h"
00019 #include <string.h>
00020 
00021 #define min(a, b) ((a < b) ? a : b)
00022 
00023 
00024 /**
00025   * Validates MQTT protocol name and version combinations
00026   * @param protocol the MQTT protocol name as an MQTTString
00027   * @param version the MQTT protocol version number, as in the connect packet
00028   * @return correct MQTT combination?  1 is true, 0 is false
00029   */
00030 int MQTTPacket_checkVersion(MQTTString* protocol, int version)
00031 {
00032     int rc = 0;
00033 
00034     if (version == 3 && memcmp(protocol->lenstring.data, "MQIsdp",
00035             min(6, protocol->lenstring.len)) == 0)
00036         rc = 1;
00037     else if (version == 4 && memcmp(protocol->lenstring.data, "MQTT",
00038             min(4, protocol->lenstring.len)) == 0)
00039         rc = 1;
00040     return rc;
00041 }
00042 
00043 
00044 /**
00045   * Deserializes the supplied (wire) buffer into connect data structure
00046   * @param data the connect data structure to be filled out
00047   * @param buf the raw buffer data, of the correct length determined by the remaining length field
00048   * @param len the length in bytes of the data in the supplied buffer
00049   * @return error code.  1 is success, 0 is failure
00050   */
00051 int MQTTDeserialize_connect(MQTTPacket_connectData* data, unsigned char* buf, int len)
00052 {
00053     MQTTHeader header = {0};
00054     MQTTConnectFlags flags = {0};
00055     unsigned char* curdata = buf;
00056     unsigned char* enddata = &buf[len];
00057     int rc = 0;
00058     MQTTString Protocol;
00059     int version;
00060     int mylen = 0;
00061 
00062     FUNC_ENTRY;
00063     header.byte = readChar(&curdata);
00064     if (header.bits.type != CONNECT)
00065         goto exit;
00066 
00067     curdata += MQTTPacket_decodeBuf(curdata, &mylen); /* read remaining length */
00068 
00069     if (!readMQTTLenString(&Protocol, &curdata, enddata) ||
00070         enddata - curdata < 0) /* do we have enough data to read the protocol version byte? */
00071         goto exit;
00072 
00073     version = (int)readChar(&curdata); /* Protocol version */
00074     /* If we don't recognize the protocol version, we don't parse the connect packet on the
00075      * basis that we don't know what the format will be.
00076      */
00077     if (MQTTPacket_checkVersion(&Protocol, version))
00078     {
00079         flags.all = readChar(&curdata);
00080         data->cleansession = flags.bits.cleansession;
00081         data->keepAliveInterval = readInt(&curdata);
00082         if (!readMQTTLenString(&data->clientID, &curdata, enddata))
00083             goto exit;
00084         data->willFlag = flags.bits.will;
00085         if (flags.bits.will)
00086         {
00087             data->will.qos = flags.bits.willQoS;
00088             data->will.retained = flags.bits.willRetain;
00089             if (!readMQTTLenString(&data->will.topicName, &curdata, enddata) ||
00090                   !readMQTTLenString(&data->will.message, &curdata, enddata))
00091                 goto exit;
00092         }
00093         if (flags.bits.username)
00094         {
00095             if (enddata - curdata < 3 || !readMQTTLenString(&data->username, &curdata, enddata))
00096                 goto exit; /* username flag set, but no username supplied - invalid */
00097             if (flags.bits.password &&
00098                 (enddata - curdata < 3 || !readMQTTLenString(&data->password, &curdata, enddata)))
00099                 goto exit; /* password flag set, but no password supplied - invalid */
00100         }
00101         else if (flags.bits.password)
00102             goto exit; /* password flag set without username - invalid */
00103         rc = 1;
00104     }
00105 exit:
00106     FUNC_EXIT_RC(rc);
00107     return rc;
00108 }
00109 
00110 
00111 /**
00112   * Serializes the connack packet into the supplied buffer.
00113   * @param buf the buffer into which the packet will be serialized
00114   * @param buflen the length in bytes of the supplied buffer
00115   * @param connack_rc the integer connack return code to be used 
00116   * @param sessionPresent the MQTT 3.1.1 sessionPresent flag
00117   * @return serialized length, or error if 0
00118   */
00119 int MQTTSerialize_connack(unsigned char* buf, int buflen, unsigned char connack_rc, unsigned char sessionPresent)
00120 {
00121     MQTTHeader header = {0};
00122     int rc = 0;
00123     unsigned char *ptr = buf;
00124     MQTTConnackFlags flags = {0};
00125 
00126     FUNC_ENTRY;
00127     if (buflen < 2)
00128     {
00129         rc = MQTTPACKET_BUFFER_TOO_SHORT;
00130         goto exit;
00131     }
00132     header.byte = 0;
00133     header.bits.type = CONNACK;
00134     writeChar(&ptr, header.byte); /* write header */
00135 
00136     ptr += MQTTPacket_encode(ptr, 2); /* write remaining length */
00137 
00138     flags.all = 0;
00139     flags.bits.sessionpresent = sessionPresent;
00140     writeChar(&ptr, flags.all); 
00141     writeChar(&ptr, connack_rc);
00142 
00143     rc = ptr - buf;
00144 exit:
00145     FUNC_EXIT_RC(rc);
00146     return rc;
00147 }
00148