UDP协议

提供的是非可靠传输，但是速度快

/*UDP头定义，共8个字节*/
typedef struct _UDP_HEADER 
{
 unsigned short m_usSourPort; // 源端口号16bit
 unsigned short m_usDestPort; // 目的端口号16bit
 unsigned short m_usLength; // 数据包长度16bit
 unsigned short m_usCheckSum; // 校验和16bit
}__attribute__((packed))UDP_HEADER, *PUDP_HEADER;