Diff: MQTT/MQTTPacket/MQTTPacket.c

Revision:

0:0a2f634d3324

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MQTT/MQTTPacket/MQTTPacket.c	Thu Feb 09 07:26:57 2017 +0000
@@ -0,0 +1,453 @@
+/*******************************************************************************
+ * 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
+ *******************************************************************************/
+
+#include "StackTrace.h"
+#include "MQTTPacket.h"
+
+#include <string.h>
+
+/**
+ * Encodes the message length according to the MQTT algorithm
+ * @param buf the buffer into which the encoded data is written
+ * @param length the length to be encoded
+ * @return the number of bytes written to buffer
+ */
+int MQTTPacket_encode(unsigned char* buf, int length)
+{
+	int rc = 0;
+
+	FUNC_ENTRY;
+	do
+	{
+		char d = length % 128;
+		length /= 128;
+		/* if there are more digits to encode, set the top bit of this digit */
+		if (length > 0)
+			d |= 0x80;
+		buf[rc++] = d;
+	} while (length > 0);
+	FUNC_EXIT_RC(rc);
+	return rc;
+}
+
+
+/**
+ * Decodes the message length according to the MQTT algorithm
+ * @param getcharfn pointer to function to read the next character from the data source
+ * @param value the decoded length returned
+ * @return the number of bytes read from the socket
+ */
+int MQTTPacket_decode(int (*getcharfn)(unsigned char*, int), int* value)
+{
+	unsigned char c;
+	int multiplier = 1;
+	int len = 0;
+#define MAX_NO_OF_REMAINING_LENGTH_BYTES 4
+
+	FUNC_ENTRY;
+	*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 = (*getcharfn)(&c, 1);
+		if (rc != 1)
+			goto exit;
+		*value += (c & 127) * multiplier;
+		multiplier *= 128;
+	} while ((c & 128) != 0);
+exit:
+	FUNC_EXIT_RC(len);
+	return len;
+}
+
+
+int MQTTPacket_len(int rem_len)
+{
+	rem_len += 1; /* header byte */
+
+	/* now remaining_length field */
+	if (rem_len < 128)
+		rem_len += 1;
+	else if (rem_len < 16384)
+		rem_len += 2;
+	else if (rem_len < 2097151)
+		rem_len += 3;
+	else
+		rem_len += 4;
+	return rem_len;
+}
+
+
+static unsigned char* bufptr;
+
+int bufchar(unsigned char* c, int count)
+{
+	int i;
+
+	for (i = 0; i < count; ++i)
+		*c = *bufptr++;
+	return count;
+}
+
+
+int MQTTPacket_decodeBuf(unsigned char* buf, int* value)
+{
+	bufptr = buf;
+	return MQTTPacket_decode(bufchar, value);
+}
+
+
+/**
+ * Calculates an integer from two bytes read from the input buffer
+ * @param pptr pointer to the input buffer - incremented by the number of bytes used & returned
+ * @return the integer value calculated
+ */
+int readInt(unsigned char** pptr)
+{
+	unsigned char* ptr = *pptr;
+	int len = 256*(*ptr) + (*(ptr+1));
+	*pptr += 2;
+	return len;
+}
+
+
+/**
+ * Reads one character from the input buffer.
+ * @param pptr pointer to the input buffer - incremented by the number of bytes used & returned
+ * @return the character read
+ */
+char readChar(unsigned char** pptr)
+{
+	char c = **pptr;
+	(*pptr)++;
+	return c;
+}
+
+
+/**
+ * Writes one character to an output buffer.
+ * @param pptr pointer to the output buffer - incremented by the number of bytes used & returned
+ * @param c the character to write
+ */
+void writeChar(unsigned char** pptr, char c)
+{
+	**pptr = c;
+	(*pptr)++;
+}
+
+
+/**
+ * Writes an integer as 2 bytes to an output buffer.
+ * @param pptr pointer to the output buffer - incremented by the number of bytes used & returned
+ * @param anInt the integer to write
+ */
+void writeInt(unsigned char** pptr, int anInt)
+{
+	**pptr = (unsigned char)(anInt / 256);
+	(*pptr)++;
+	**pptr = (unsigned char)(anInt % 256);
+	(*pptr)++;
+}
+
+
+/**
+ * Writes a "UTF" string to an output buffer.  Converts C string to length-delimited.
+ * @param pptr pointer to the output buffer - incremented by the number of bytes used & returned
+ * @param string the C string to write
+ */
+void writeCString(unsigned char** pptr, const char* string)
+{
+	int len = strlen(string);
+	writeInt(pptr, len);
+	memcpy(*pptr, string, len);
+	*pptr += len;
+}
+
+
+int getLenStringLen(char* ptr)
+{
+	int len = 256*((unsigned char)(*ptr)) + (unsigned char)(*(ptr+1));
+	return len;
+}
+
+
+void writeMQTTString(unsigned char** pptr, MQTTString mqttstring)
+{
+	if (mqttstring.lenstring.len > 0)
+	{
+		writeInt(pptr, mqttstring.lenstring.len);
+		memcpy(*pptr, mqttstring.lenstring.data, mqttstring.lenstring.len);
+		*pptr += mqttstring.lenstring.len;
+	}
+	else if (mqttstring.cstring)
+		writeCString(pptr, mqttstring.cstring);
+	else
+		writeInt(pptr, 0);
+}
+
+
+/**
+ * @param mqttstring the MQTTString structure into which the data is to be read
+ * @param pptr pointer to the output buffer - incremented by the number of bytes used & returned
+ * @param enddata pointer to the end of the data: do not read beyond
+ * @return 1 if successful, 0 if not
+ */
+int readMQTTLenString(MQTTString* mqttstring, unsigned char** pptr, unsigned char* enddata)
+{
+	int rc = 0;
+
+	FUNC_ENTRY;
+	/* the first two bytes are the length of the string */
+	if (enddata - (*pptr) > 1) /* enough length to read the integer? */
+	{
+		mqttstring->lenstring.len = readInt(pptr); /* increments pptr to point past length */
+		if (&(*pptr)[mqttstring->lenstring.len] <= enddata)
+		{
+			mqttstring->lenstring.data = (char*)*pptr;
+			*pptr += mqttstring->lenstring.len;
+			rc = 1;
+		}
+	}
+	mqttstring->cstring = NULL;
+	FUNC_EXIT_RC(rc);
+	return rc;
+}
+
+
+/**
+ * Return the length of the MQTTstring - C string if there is one, otherwise the length delimited string
+ * @param mqttstring the string to return the length of
+ * @return the length of the string
+ */
+int MQTTstrlen(MQTTString mqttstring)
+{
+	int rc = 0;
+
+	if (mqttstring.cstring)
+		rc = strlen(mqttstring.cstring);
+	else
+		rc = mqttstring.lenstring.len;
+	return rc;
+}
+
+
+/**
+ * Compares an MQTTString to a C string
+ * @param a the MQTTString to compare
+ * @param bptr the C string to compare
+ * @return boolean - equal or not
+ */
+int MQTTPacket_equals(MQTTString* a, char* bptr)
+{
+	int alen = 0,
+		blen = 0;
+	char *aptr;
+	
+	if (a->cstring)
+	{
+		aptr = a->cstring;
+		alen = strlen(a->cstring);
+	}
+	else
+	{
+		aptr = a->lenstring.data;
+		alen = a->lenstring.len;
+	}
+	blen = strlen(bptr);
+	
+	return (alen == blen) && (strncmp(aptr, bptr, alen) == 0);
+}
+
+
+/**
+ * Helper function to read packet data from some source into a buffer
+ * @param buf the buffer into which the packet will be serialized
+ * @param buflen the length in bytes of the supplied buffer
+ * @param getfn pointer to a function which will read any number of bytes from the needed source
+ * @return integer MQTT packet type, or -1 on error
+ */
+int MQTTPacket_read(unsigned char* buf, int buflen, int (*getfn)(unsigned char*, int))
+{
+	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 ((*getfn)(buf, 1) != 1)
+		goto exit;
+
+	len = 1;
+	/* 2. read the remaining length.  This is variable in itself */
+	MQTTPacket_decode(getfn, &rem_len);
+	len += MQTTPacket_encode(buf + 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 ((*getfn)(buf + len, rem_len) != rem_len)
+		goto exit;
+
+	header.byte = buf[0];
+	rc = header.bits.type;
+exit:
+	return rc;
+}
+
+
+const char* MQTTPacket_names[] =
+{
+	"RESERVED", "CONNECT", "CONNACK", "PUBLISH", "PUBACK", "PUBREC", "PUBREL",
+	"PUBCOMP", "SUBSCRIBE", "SUBACK", "UNSUBSCRIBE", "UNSUBACK",
+	"PINGREQ", "PINGRESP", "DISCONNECT"
+};
+
+
+char* MQTTPacket_toString(char* strbuf, int strbuflen, unsigned char* buf, int buflen)
+{
+	int index = 0;
+	int rem_length = 0;
+	MQTTHeader header = {0};
+	int strindex = 0;
+
+	header.byte = buf[index++];
+	index += MQTTPacket_decodeBuf(&buf[index], &rem_length);
+
+	switch (header.bits.type)
+	{
+	case CONNECT:
+	{
+		MQTTPacket_connectData data;
+		if (MQTTDeserialize_connect(&data, buf, buflen) == 1)
+		{
+			strindex = snprintf(strbuf, strbuflen,
+				"CONNECT MQTT version %d, client id %.*s, clean session %d, keep alive %hd",
+				(int)data.MQTTVersion, data.clientID.lenstring.len, data.clientID.lenstring.data,
+				(int)data.cleansession, data.keepAliveInterval);
+			if (data.willFlag)
+				strindex += snprintf(&strbuf[strindex], strbuflen - strindex,
+				", will QoS %d, will retain %d, will topic %.*s, will message %.*s",
+				data.will.qos, data.will.retained,
+				data.will.topicName.lenstring.len, data.will.topicName.lenstring.data,
+				data.will.message.lenstring.len, data.will.message.lenstring.data);
+			if (data.username.lenstring.data && data.username.lenstring.len > 0)
+			{
+				printf("user name\n");
+				strindex += snprintf(&strbuf[strindex], strbuflen - strindex,
+				", user name %.*s", data.username.lenstring.len, data.username.lenstring.data);
+			}
+			if (data.password.lenstring.data && data.password.lenstring.len > 0)
+				strindex += snprintf(&strbuf[strindex], strbuflen - strindex,
+				", password %.*s", data.password.lenstring.len, data.password.lenstring.data);
+		}
+	}
+	break;
+	case CONNACK:
+	{
+		unsigned char sessionPresent, connack_rc;
+		if (MQTTDeserialize_connack(&sessionPresent, &connack_rc, buf, buflen) == 1)
+			strindex = snprintf(strbuf, strbuflen,
+			"CONNACK session present %d, rc %d", sessionPresent, connack_rc);
+	}
+	break;
+	case PUBLISH:
+	{
+		unsigned char dup, retained, *payload;
+		unsigned short packetid;
+		int qos, payloadlen;
+		MQTTString topicName = MQTTString_initializer;
+		if (MQTTDeserialize_publish(&dup, &qos, &retained, &packetid, &topicName,
+				&payload, &payloadlen, buf, buflen) == 1)
+			strindex = snprintf(strbuf, strbuflen,
+				"PUBLISH dup %d, QoS %d, retained %d, packet id %d, topic %.*s, payload length %d, payload %.*s",
+				dup, qos, retained, packetid,
+				(topicName.lenstring.len < 20) ? topicName.lenstring.len : 20, topicName.lenstring.data,
+				payloadlen, (payloadlen < 20) ? payloadlen : 20, payload);
+	}
+	break;
+	case PUBACK:
+	case PUBREC:
+	case PUBREL:
+	case PUBCOMP:
+	{
+		unsigned char packettype, dup;
+		unsigned short packetid;
+		if (MQTTDeserialize_ack(&packettype, &dup, &packetid, buf, buflen) == 1)
+			strindex = snprintf(strbuf, strbuflen,
+				"%s dup %d, packet id %d",
+				MQTTPacket_names[packettype], dup, packetid);
+	}
+	break;
+	case SUBSCRIBE:
+	{
+		unsigned char dup;
+		unsigned short packetid;
+		int maxcount = 1, count = 0;
+		MQTTString topicFilters[1];
+		int requestedQoSs[1];
+		if (MQTTDeserialize_subscribe(&dup, &packetid, maxcount, &count,
+				topicFilters, requestedQoSs, buf, buflen) == 1)
+			strindex = snprintf(strbuf, strbuflen,
+				"SUBSCRIBE dup %d, packet id %d count %d topic %.*s qos %d",
+				dup, packetid, count,
+				topicFilters[0].lenstring.len, topicFilters[0].lenstring.data,
+				requestedQoSs[0]);
+	}
+	break;
+	case SUBACK:
+	{
+		unsigned short packetid;
+		int maxcount = 1, count = 0;
+		int grantedQoSs[1];
+		if (MQTTDeserialize_suback(&packetid, maxcount, &count, grantedQoSs, buf, buflen) == 1)
+			strindex = snprintf(strbuf, strbuflen,
+				"SUBACK packet id %d count %d granted qos %d",
+				packetid, count, grantedQoSs[0]);
+	}
+	break;
+	case UNSUBSCRIBE:
+	{
+		unsigned char dup;
+		unsigned short packetid;
+		int maxcount = 1, count = 0;
+		MQTTString topicFilters[1];
+		if (MQTTDeserialize_unsubscribe(&dup, &packetid, maxcount, &count, topicFilters, buf, buflen) == 1)
+			strindex = snprintf(strbuf, strbuflen,
+				"UNSUBSCRIBE dup %d, packet id %d count %d topic %.*s",
+				dup, packetid, count,
+				topicFilters[0].lenstring.len, topicFilters[0].lenstring.data);
+	}
+	break;
+	case UNSUBACK:
+	{
+		unsigned short packetid;
+		if (MQTTDeserialize_unsuback(&packetid, buf, buflen) == 1)
+			strindex = snprintf(strbuf, strbuflen,
+				"UNSUBACK packet id %d", packetid);
+	}
+	break;
+	case PINGREQ:
+	case PINGRESP:
+	case DISCONNECT:
+		strindex = snprintf(strbuf, strbuflen, "%s", MQTTPacket_names[header.bits.type]);
+		break;
+	}
+	return strbuf;
+}