/// <summary>
/// 解析TLV
/// </summary>
/// <param name="list"></param>
/// <returns></returns>
public static byte[] Parse(List <TLVEntity> list)
{
byte[] buffer = new byte[4096];
int currentIndex = 0;
int currentTLVIndex = 0;
int valueSize = 0;
while (currentTLVIndex < list.Count())
{
valueSize = 0;
TLVEntity entity = list[currentTLVIndex];
Array.Copy(entity.Tag, 0, buffer, currentIndex, entity.TagSize); //解析Tag
currentIndex += entity.TagSize;
for (int index = 0; index < entity.LengthSize; index++)
{
valueSize += entity.Length[index] << (index * 8); //计算Length域的长度
}
if (valueSize > 127)
{
buffer[currentIndex] = Convert.ToByte(0x80 | entity.LengthSize);
currentIndex += 1;
}
Array.Copy(entity.Length, 0, buffer, currentIndex, entity.LengthSize); //解析Length
currentIndex += entity.LengthSize;
//判断是否包含子嵌套TLV
if (entity.Sub_TLVEntity == null)
{
Array.Copy(entity.Value, 0, buffer, currentIndex, valueSize); //解析Value
currentIndex += valueSize;
}
else
{
byte[] tempBuffer = Parse(new List <TLVEntity> {
entity.Sub_TLVEntity
});
Array.Copy(tempBuffer, 0, buffer, currentIndex, tempBuffer.Length); //解析子嵌套TLV
currentIndex += tempBuffer.Length;
}
currentTLVIndex++;
}
byte[] resultBuffer = new byte[currentIndex];
Array.Copy(buffer, 0, resultBuffer, 0, currentIndex);
return(resultBuffer);
}
/// <summary>
/// 构造TLV
/// </summary>
/// <param name="buffer"></param>
public static List <TLVEntity> Construct(byte[] buffer)
{
List <TLVEntity> list = new List <TLVEntity>();
int currentIndex = 0;
int currentStatus = 'T'; //状态字符
int valueSize = 0;
TLVEntity tlvEntity = null;
while (currentIndex < buffer.Length)
{
switch (currentStatus)
{
case 'T':
tlvEntity = new TLVEntity();
valueSize = 0;
//判断是否单一结构
if ((buffer[currentIndex] & 0x20) != 0x20)
{
tlvEntity.Sub_TLVEntity = null; //单一结构时将子Tag置空【】
//判断是否多字节Tag
if ((buffer[currentIndex] & 0x1f) == 0x1f)
{
int endTagIndex = currentIndex;
while ((buffer[++endTagIndex] & 0x80) == 0x80)
{
; //判断第二个字节的最高位是否为1
}
int tagSize = endTagIndex - currentIndex + 1; //计算Tag包含多少字节
tlvEntity.Tag = new byte[tagSize];
Array.Copy(buffer, currentIndex, tlvEntity.Tag, 0, tagSize);
tlvEntity.TagSize = tagSize;
currentIndex += tagSize;
}
else
{
tlvEntity.Tag = new byte[1];
Array.Copy(buffer, currentIndex, tlvEntity.Tag, 0, 1);
tlvEntity.TagSize = 1;
currentIndex += 1;
}
}
else
{
//判断是否多字节Tag
if ((buffer[currentIndex] & 0x1f) == 0x1f)
{
int endTagIndex = currentIndex;
while ((buffer[++endTagIndex] & 0x80) == 0x80)
{
; //判断第二个字节的最高位是否为1
}
int tagSize = endTagIndex - currentIndex + 1; //计算Tag包含多少字节
tlvEntity.Tag = new byte[tagSize];
Array.Copy(buffer, currentIndex, tlvEntity.Tag, 0, tagSize);
tlvEntity.TagSize = tagSize;
currentIndex += tagSize;
}
else
{
tlvEntity.Tag = new byte[1];
Array.Copy(buffer, currentIndex, tlvEntity.Tag, 0, 1);
tlvEntity.TagSize = 1;
currentIndex += 1;
}
//分析SubTag
int subLength = 0;
byte[] temp;
if ((buffer[currentIndex] & 0x80) == 0x80)
{
for (int index = 0; index < 2; index++)
{
subLength += buffer[currentIndex + 1 + index] << (index * 8); //计算Length域的长度
}
temp = new byte[subLength];
Array.Copy(buffer, currentIndex + 3, temp, 0, subLength);
}
else
{
subLength = buffer[currentIndex];
temp = new byte[subLength];
Array.Copy(buffer, currentIndex + 1, temp, 0, subLength);
}
tlvEntity.Sub_TLVEntity = new TLVEntity();
List <TLVEntity> tempList = Construct(temp);
tlvEntity.Sub_TLVEntity = tempList[0];
}
currentStatus = 'L';
break;
case 'L':
//判断长度字节的最高位是否为1，如果为1，则该字节为长度扩展字节，由下一个字节开始决定长度
if ((buffer[currentIndex] & 0x80) != 0x80)
{
tlvEntity.Length = new byte[1];
Array.Copy(buffer, currentIndex, tlvEntity.Length, 0, 1);
tlvEntity.LengthSize = 1;
valueSize = tlvEntity.Length[0];
currentIndex += 1;
}
else
{
//为1的情况
int lengthSize = buffer[currentIndex] & 0x7f;
currentIndex += 1; //从下一个字节开始算Length域
for (int index = 0; index < lengthSize; index++)
{
valueSize += buffer[currentIndex + index] << (index * 8); //计算Length域的长度
}
tlvEntity.Length = new byte[lengthSize];
Array.Copy(buffer, currentIndex, tlvEntity.Length, 0, lengthSize);
tlvEntity.LengthSize = lengthSize;
currentIndex += lengthSize;
}
currentStatus = 'V';
break;
case 'V':
tlvEntity.Value = new byte[valueSize];
Array.Copy(buffer, currentIndex, tlvEntity.Value, 0, valueSize);
currentIndex += valueSize;
//进入下一个TLV构造循环
list.Add(tlvEntity);
currentStatus = 'T';
break;
default:
return(new List <TLVEntity>());
}
}
return(list);
}
