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tracker/common/UtlMsgBuffer.cpp

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+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+// $NoKeywords: $
+//=============================================================================
+
+#include "UtlMsgBuffer.h"
+
+#include <string.h>
+
+//-----------------------------------------------------------------------------
+// Purpose: bitfields for use in variable descriptors
+//-----------------------------------------------------------------------------
+enum
+{
+	PACKBIT_CONTROLBIT	= 0x01,		// this must always be set
+	PACKBIT_INTNAME		= 0x02,		// if this is set then it's an int named variable, instead of a string
+	PACKBIT_BINARYDATA  = 0x04,		// signifies the data in this variable is binary, it's not a string
+};
+
+//-----------------------------------------------------------------------------
+// Purpose: Constructor
+//-----------------------------------------------------------------------------
+CUtlMsgBuffer::CUtlMsgBuffer(unsigned short msgID, int initialSize) : m_Memory(0, initialSize)
+{
+	m_iMsgID = msgID;
+	m_iWritePos = 0;
+	m_iReadPos = 0;
+	m_iNextVarPos = 0;
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Constructor, takes initial data
+//-----------------------------------------------------------------------------
+CUtlMsgBuffer::CUtlMsgBuffer(unsigned short msgID, void const *data, int dataSize) : m_Memory(0, dataSize)
+{
+	m_iMsgID = msgID;
+	m_iWritePos = (short)dataSize;
+	m_iReadPos = 0;
+	m_iNextVarPos = 0;
+
+	memcpy(Base(), data, dataSize);
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Destructor
+//-----------------------------------------------------------------------------
+CUtlMsgBuffer::~CUtlMsgBuffer()
+{
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Copy
+//-----------------------------------------------------------------------------
+CUtlMsgBuffer &CUtlMsgBuffer::Copy(const CUtlMsgBuffer &rhs)
+{
+	m_iWritePos = rhs.m_iWritePos;
+	m_iReadPos = rhs.m_iReadPos;
+	m_iNextVarPos = rhs.m_iNextVarPos;
+
+	m_Memory.EnsureCapacity(rhs.m_Memory.NumAllocated());
+	if ( rhs.m_Memory.NumAllocated() > 0 )
+	{
+		memcpy(Base(), rhs.Base(), rhs.m_Memory.NumAllocated());
+	}
+	return *this;
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Writes string data to the message
+// Input  : *name - name of the variable
+//			*data - pointer to the string data to write
+//-----------------------------------------------------------------------------
+void CUtlMsgBuffer::WriteString(const char *name, const char *data)
+{
+	// write out the variable type
+	unsigned char vtype = PACKBIT_CONTROLBIT;	// stringname var, string data
+	Write(&vtype, 1);
+	
+	// write out the variable name
+	Write(name, strlen(name) + 1);
+
+	// write out the size of the data
+	unsigned short size = (unsigned short)(strlen(data) + 1);
+	Write(&size, 2);
+
+	// write out the data itself
+	Write(data, size);
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Writes out a named block of data
+//-----------------------------------------------------------------------------
+void CUtlMsgBuffer::WriteBlob(const char *name, const void *data, int dataSize)
+{
+	// write out the variable type
+	unsigned char vtype = PACKBIT_CONTROLBIT | PACKBIT_BINARYDATA;	// stringname var, binary data
+	Write(&vtype, 1);
+	
+	// write out the variable name
+	Write(name, strlen(name) + 1);
+
+	// write out the size of the data
+	unsigned short size = (unsigned short)dataSize;
+	Write(&size, 2);
+
+	// write out the data itself
+	Write(data, dataSize);
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Writes out another UtlMsgBuffer as an element of this one
+//-----------------------------------------------------------------------------
+void CUtlMsgBuffer::WriteBuffer(const char *name, const CUtlMsgBuffer *buffer)
+{
+	// write out the variable type
+	unsigned char vtype = PACKBIT_CONTROLBIT | PACKBIT_BINARYDATA;	// stringname var, binary data
+	Write(&vtype, 1);
+
+	// write out the variable name
+	Write(name, strlen(name) + 1);
+
+	// write out the size of the data
+	unsigned short size = (unsigned short) buffer->DataSize();
+	Write(&size, 2);
+
+    // write out the data itself
+    Write(buffer->Base(), size);
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Reads from the buffer, increments read position
+//			returns false if past end of buffer
+//-----------------------------------------------------------------------------
+bool CUtlMsgBuffer::Read(void *buffer, int readAmount)
+{
+	if (m_iReadPos + readAmount >= m_iWritePos)
+		return false;
+
+	memcpy(buffer, &m_Memory[m_iReadPos], readAmount);
+	m_iReadPos += readAmount;
+	return true;
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Reads characterse from the buffer until a null is hit
+//-----------------------------------------------------------------------------
+bool CUtlMsgBuffer::ReadUntilNull(void *buffer, int bufferSize)
+{
+	int nullPos = m_iReadPos;
+
+	// look through the buffer for the null terminator
+	while (nullPos < m_Memory.NumAllocated() && m_Memory[nullPos] != 0)
+	{
+		nullPos++;
+	}
+	
+	if (nullPos >= m_Memory.NumAllocated())
+	{
+		// never found a null terminator
+		((char *)buffer)[0] = 0;
+		return false;
+	}
+
+	// copy from the null terminator
+	int copySize = nullPos - m_iReadPos;
+	if (copySize > bufferSize)
+	{
+		copySize = bufferSize - 1;
+	}
+
+	// copy out the data and return
+	memcpy(buffer, &m_Memory[m_iReadPos], copySize);
+	((char *)buffer)[copySize] = 0;
+	m_iReadPos += (copySize+1);
+	return true;
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Writes to the buffer, incrementing the write position
+//			assumes enough space has already been allocated for the write
+//-----------------------------------------------------------------------------
+void CUtlMsgBuffer::Write(void const *data, int size)
+{
+	// make sure it will fit
+	m_Memory.EnsureCapacity(m_iWritePos + size);
+		
+	// normal write
+	memcpy(&m_Memory[m_iWritePos], data, size);
+
+	// increment write position
+	m_iWritePos += size;
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Reads in a named variable length data blob
+//			returns number of bytes read, 0 on failure
+//-----------------------------------------------------------------------------
+int CUtlMsgBuffer::ReadBlob(const char *name, void *data, int dataBufferSize)
+{
+	int dataSize = 0;
+	char *readData = (char *)FindVar(name, dataSize);
+	if (!readData)
+	{
+		memset(data, 0, dataBufferSize);
+		return 0;
+	}
+
+	// ensure against buffer overflow
+	if (dataSize > dataBufferSize)
+		dataSize = dataBufferSize;
+
+	// copy out data
+	memcpy(data, readData, dataSize);
+	return dataSize;
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Reads a blob of binary data into it's own buffer
+//-----------------------------------------------------------------------------
+bool CUtlMsgBuffer::ReadBuffer(const char *name, CUtlMsgBuffer &buffer)
+{
+	int dataSize = 0;
+	char *readData = (char *)FindVar(name, dataSize);
+	if (!readData)
+	{
+		return false;
+	}
+
+	buffer.m_Memory.EnsureCapacity(dataSize);
+	memcpy(&buffer.m_Memory[0], readData, dataSize);
+	buffer.m_iReadPos = 0;
+	buffer.m_iWritePos = (short)dataSize;
+	return true;
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: reads out the next variable available in the buffer
+//			fills out parameters with var details and data
+//			returns false if no more vars available
+//-----------------------------------------------------------------------------
+bool CUtlMsgBuffer::ReadNextVar(char varname[32], bool &stringData, void *data, int &dataSize)
+{
+	// read the type
+	unsigned char vtype = 1;
+	if (!Read(&vtype, 1))
+		return false;
+
+	// check for null-termination type
+	if (vtype == 0)
+		return false;
+
+	stringData = !(vtype & PACKBIT_BINARYDATA);
+
+	// read the variable name
+	if (!ReadUntilNull(varname, 31))
+		return false;
+
+	// read the data size
+	unsigned short size = 0;
+	if (!Read(&size, 2))
+		return false;
+
+	// ensure against buffer overflows
+	if (dataSize > size)
+		dataSize = size;
+
+	// copy data
+	memcpy(data, &m_Memory[m_iReadPos], dataSize);
+
+	// store of the next position, since that is probably where the next read needs to occur
+	m_iReadPos += size;
+	m_iNextVarPos = m_iReadPos;
+	return true;
+}
+
+
+//-----------------------------------------------------------------------------
+// Purpose: sets the read/write position to be at the specified variable
+//			returns pointer to buffer position on success, NULL if not found
+//-----------------------------------------------------------------------------
+void *CUtlMsgBuffer::FindVar(const char *name, int &dataSize)
+{
+	// reset to where we Think the next var will be read from
+	m_iReadPos = m_iNextVarPos;
+	int loopCount = 2;
+
+	// loop through looking for the specified variable
+	while (loopCount--)
+	{
+		unsigned char vtype = 1;
+		while (Read(&vtype, 1))
+		{
+			// check for null-termination type
+			if (vtype == 0)
+				break;
+
+			// read the variable name
+			char varname[32];
+			if (!ReadUntilNull(varname, 31))
+				break;
+
+			// read the data size
+			unsigned short size = 0;
+			if (!Read(&size, 2))
+				break;
+
+			// is this our variable?
+			if (!stricmp(varname, name))
+			{
+				dataSize = size;
+				void *data = &m_Memory[m_iReadPos];
+
+				// store of the next position, since that is probably where the next read needs to occur
+				m_iReadPos += size;
+				m_iNextVarPos = m_iReadPos;
+				return data;
+			}
+
+			// skip over the data block to the next variable
+			m_iReadPos += size;
+			if (m_iReadPos >= m_iWritePos)
+				break;
+		}
+
+		// we haven't found the data yet, Start again
+		m_iReadPos = 0;
+	}
+
+	return NULL;
+}