【TLV】非递归TLV数据解析

#include <stdio.h>


#define X_LEN_OF_TAG_MAX        ( 2 )
#define X_LEN_OF_LEN_MAX        ( 2 )

struct st_tlv_t {
    unsigned int TAG;
    unsigned char isCustructed;
    unsigned int valLen;
    unsigned char *pVal;

};

static int skipZeroBytes( unsigned char **pcur, unsigned char *end )
{
    while( **pcur == 0 && (*pcur < end) )
        (*pcur)++;
        
    if( *pcur < end )
        return 1;
        
    return 0;    
}

static int parseTag( unsigned char **pcur, unsigned char *end, struct st_tlv_t *tlv )
{
    unsigned char *pp;
    int lenOfTag;
    int i;
    
    if( *pcur >= end )
        return 0;
        
    pp = *pcur;

    lenOfTag = 1;
    if( (*pp++ & 0x1f) == 0x1f )
    {
        do {
            if( pp >= end )
                return 0;
            
            lenOfTag++;    
        } while( (*pp++) & 0x80 );    
    }
    if( lenOfTag > X_LEN_OF_TAG_MAX )
    {
        return 0;    
    }
        
    tlv->isCustructed = ( **pcur & ( 1 << 5 ) ) ? 1 : 0;
    
    tlv->TAG = 0;
    for( i = 0; i < lenOfTag; i++ )
    {
        tlv->TAG <<= 8;
        tlv->TAG |= *(*pcur + i );
    }
    
    (*pcur) += lenOfTag;
    //printf("tlv->TAG:%x
", tlv->TAG);
    return 1;
}

static int parseLength( unsigned char **pcur, unsigned char *end, struct st_tlv_t *tlv )
{
    unsigned char *pp;
    int lenOfLen;
    int i;
    
    if( *pcur >= end || **pcur == 0 )
        return 0;
        
    pp = *pcur;
    
    if( *pp & 0x80 )
    {
        lenOfLen = *pp & 0x7F;
        if( pp + lenOfLen >= end )
            return 0;
        if( lenOfLen > X_LEN_OF_LEN_MAX )
            return 0;
        pp++;
        tlv->valLen = 0;
        for( i = 0; i < lenOfLen; i++ )
        {
            tlv->valLen <<= 8;
            tlv->valLen |= *(pp + i );
        }
        (*pcur) += (lenOfLen+1);
    }
    else
    {
        tlv->valLen = **pcur;
        (*pcur)++;
    }
    //printf("tlv->valLen:%d
", tlv->valLen);
    return 1;
}

static int parseValue( unsigned char **pcur, unsigned char *end, struct st_tlv_t *tlv )
{
    if( (*pcur + tlv->valLen) > end )
        return 0;
        
    tlv->pVal = ( unsigned char *)(*pcur);
    
    return 1;    
}


int parseTlv( unsigned char *buffer, int length, struct st_tlv_t *tlv )
{
    unsigned char *cur;
    unsigned char *end;
    
    cur = buffer;
    end = buffer + length;
    
    if( !skipZeroBytes( &cur, end ) )
        return 0;
        
    if( !parseTag( &cur, end, tlv ) )
        return 0;

    if( !parseLength( &cur, end, tlv ) )
        return 0;

    if( !parseValue( &cur, end, tlv ) )
        return 0;
    
    return 1;
}

int printTlv( struct st_tlv_t *tlv )
{
    int i;
    printf("
[%x] len:%d
", tlv->TAG, tlv->valLen);
    for( i = 0; i < tlv->valLen; i++ )
        printf("%02x", tlv->pVal[i]);
    printf("
");
    
    return 0;
}

int parseTlvXXX(  unsigned char *buffer, int length, int reverse )
{
    unsigned char *cur;
    unsigned char *end;    
    struct st_tlv_t tlv;
    
    cur = buffer;
    end = buffer + length;

    while( cur < end )
    {
        if( !parseTlv( cur, end-cur, &tlv ) )
            return 0;
        
        printTlv( &tlv );
        
        // 如果是复合型的TAG，则进入复合TAG内部继续分析
        if( tlv.isCustructed && reverse )
        {
            cur = tlv.pVal;
        }
        else // 如果是简单型的TAG，则分析下一个TAG
        {
            cur = tlv.pVal + tlv.valLen;
        }
    }

    
    if( cur > end )
        return 0;

    return 1;
}

int main( void )
{
    int ret;
    
    unsigned char tlv_buf0[] = {
        0x70,0x28,0x61,0x26,0x4f,0x07,0xa0,0x00,
        0x00,0x03,0x33,0x01,0x01,0x50,0x0b,0x50,
        0x42,0x4f,0x43,0x20,0x43,0x72,0x65,0x64,
        0x69,0x74,0x87,0x01,0x01,0x9f,0x12,0x0a,
        0x50,0x42,0x4f,0x43,0x20,0x44,0x45,0x42,
        0x49,0x54,0x90,0x00
    };
    unsigned char tlv_buf1[] = {
        0x00,0x00,0x00,
        0x70,0x81,0x83,0x90,0x81,0x80,0x25,0x3c,
        0x3c,0x1f,0xd9,0x92,0x8d,0x88,0x21,0x11,
        0xa6,0xac,0x4c,0xa2,0x07,0xdf,0x93,0x10,
        0x64,0x23,0x95,0xea,0x09,0x7b,0x3c,0xb1,
        0x6d,0x51,0x76,0x53,0x35,0x38,0x03,0xc2,
        0xc1,0x03,0x3e,0x4a,0xac,0xb9,0x73,0x5d,
        0x2e,0x69,0xca,0x49,0x8f,0xeb,0x4c,0xc0,
        0xae,0xe1,0xff,0xc7,0xf5,0x44,0x83,0x09,
        0x3a,0x30,0xcc,0xbf,0x6b,0x20,0x11,0xd6,
        0x09,0xe5,0x2f,0xd7,0x87,0x76,0xb6,0x6b,
        0x6d,0x86,0x95,0xcb,0xc0,0x46,0x21,0x6b,
        0xf8,0x1c,0x52,0xd5,0xc2,0xf9,0x47,0xde,
        0xe3,0xad,0xd7,0x20,0x9a,0xb3,0x27,0xf2,
        0x9c,0x10,0x6b,0xfa,0x0e,0x29,0x1d,0x9d,
        0xab,0x00,0x91,0x06,0xf4,0x89,0xba,0x59,
        0x43,0x6d,0xa9,0x46,0x75,0xdf,0x9d,0x31,
        0xdc,0xaf,0xbd,0x6a,0xbe,0x20,
    };
    unsigned char tlv_buf2[] = {
        0x6f,0x24,0x84,0x0e,0x31,0x50,0x41,0x59,
        0x2e,0x53,0x59,0x53,0x2e,0x44,0x44,0x46,
        0x30,0x31,0xa5,0x12,0x88,0x01,0x01,0x5f,
        0x2d,0x08,0x7a,0x68,0x65,0x6e,0x66,0x72,
        0x64,0x65,0x9f,0x11,0x01,0x01    
    };

    ret = parseTlvXXX( tlv_buf0, sizeof(tlv_buf0), 0 );
    printf("0-parseTlvXX: %d
", ret);

    ret = parseTlvXXX( tlv_buf1, sizeof(tlv_buf1), 1 );
    printf("1-parseTlvXX: %d
", ret);
    

    ret = parseTlvXXX( tlv_buf2, sizeof(tlv_buf2), 1 );
    printf("2-parseTlvXX: %d
", ret);
    
    return 0;    
}