/* BEGIN_HEADER */
#include "mbedtls/entropy.h"
#include "mbedtls/ctr_drbg.h"
#include "string.h"

/* Modes for ctr_drbg_validate */
enum reseed_mode
{
    RESEED_NEVER, /* never reseed */
    RESEED_FIRST, /* instantiate, reseed, generate, generate */
    RESEED_SECOND, /* instantiate, generate, reseed, generate */
    RESEED_ALWAYS /* prediction resistance, no explicit reseed */
};

static size_t test_offset_idx;
static size_t test_max_idx;
static int mbedtls_test_entropy_func( void *data, unsigned char *buf, size_t len )
{
    const unsigned char *p = (unsigned char *) data;
    if( test_offset_idx + len > test_max_idx )
        return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
    memcpy( buf, p + test_offset_idx, len );
    test_offset_idx += len;
    return( 0 );
}
/* END_HEADER */

/* BEGIN_DEPENDENCIES
 * depends_on:MBEDTLS_CTR_DRBG_C
 * END_DEPENDENCIES
 */

/* BEGIN_CASE */
void ctr_drbg_special_behaviours(  )
{
    mbedtls_ctr_drbg_context ctx;
    unsigned char output[512];
    unsigned char additional[512];

    mbedtls_ctr_drbg_init( &ctx );
    memset( output, 0, sizeof( output ) );
    memset( additional, 0, sizeof( additional ) );

    TEST_ASSERT( mbedtls_ctr_drbg_random_with_add( &ctx,
                        output, MBEDTLS_CTR_DRBG_MAX_REQUEST + 1,
                        additional, 16 ) ==
                        MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG );
    TEST_ASSERT( mbedtls_ctr_drbg_random_with_add( &ctx,
                        output, 16,
                        additional, MBEDTLS_CTR_DRBG_MAX_INPUT + 1 ) ==
                        MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );

    TEST_ASSERT( mbedtls_ctr_drbg_reseed( &ctx, additional,
                        MBEDTLS_CTR_DRBG_MAX_SEED_INPUT + 1 ) ==
                        MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );

    mbedtls_ctr_drbg_set_entropy_len( &ctx, ~0 );
    TEST_ASSERT( mbedtls_ctr_drbg_reseed( &ctx, additional,
                        MBEDTLS_CTR_DRBG_MAX_SEED_INPUT ) ==
                        MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG );
exit:
    mbedtls_ctr_drbg_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE */
void ctr_drbg_validate( int reseed_mode, char *nonce_string,
                        int entropy_len_arg, char *entropy_string,
                        char *reseed_string,
                        char *add1_string, char *add2_string,
                        char *result_string )
{
    unsigned char entropy[144];
    unsigned char nonce[64];
    unsigned char reseed[32];
    unsigned char add1[48];
    unsigned char add2[48];
    mbedtls_ctr_drbg_context ctx;
    unsigned char buf[64];
    unsigned char result[64];
    size_t entropy_chunk_len = (size_t) entropy_len_arg;
    size_t nonce_len, reseed_len, add1_len, add2_len, result_len;

    test_offset_idx = 0;
    mbedtls_ctr_drbg_init( &ctx );

    test_max_idx = unhexify( entropy, entropy_string );
    nonce_len = unhexify( nonce, nonce_string );
    reseed_len = unhexify( reseed, reseed_string );
    add1_len = unhexify( add1, add1_string );
    add2_len = unhexify( add2, add2_string );
    result_len = unhexify( result, result_string );

    /* CTR_DRBG_Instantiate(entropy[:entropy_len], nonce, perso, <ignored>)
     * where nonce||perso = nonce[nonce_len] */
    TEST_ASSERT( mbedtls_ctr_drbg_seed_entropy_len(
                     &ctx,
                     mbedtls_test_entropy_func, entropy,
                     nonce, nonce_len,
                     entropy_chunk_len ) == 0 );
    if( reseed_mode == RESEED_ALWAYS )
        mbedtls_ctr_drbg_set_prediction_resistance(
            &ctx,
            MBEDTLS_CTR_DRBG_PR_ON );

    if( reseed_mode == RESEED_FIRST )
    {
        /* CTR_DRBG_Reseed(entropy[idx:idx+entropy_len],
         *                 reseed[:reseed_len]) */
        TEST_ASSERT( mbedtls_ctr_drbg_reseed(
                         &ctx,
                         reseed, reseed_len ) == 0 );
    }

    /* CTR_DRBG_Generate(result_len * 8 bits, add1[:add1_len]) -> buf */
    /* Then reseed if prediction resistance is enabled. */
    TEST_ASSERT( mbedtls_ctr_drbg_random_with_add(
                     &ctx,
                     buf, result_len,
                     add1, add1_len ) == 0 );


    if( reseed_mode == RESEED_SECOND )
    {
        /* CTR_DRBG_Reseed(entropy[idx:idx+entropy_len],
         *                 reseed[:reseed_len]) */
        TEST_ASSERT( mbedtls_ctr_drbg_reseed(
                         &ctx,
                         reseed, reseed_len ) == 0 );
    }

    /* CTR_DRBG_Generate(result_len * 8 bits, add2[:add2_len]) -> buf */
    /* Then reseed if prediction resistance is enabled. */
    TEST_ASSERT( mbedtls_ctr_drbg_random_with_add(
                     &ctx,
                     buf, result_len,
                     add2, add2_len ) == 0 );
    TEST_ASSERT( memcmp( buf, result, result_len ) == 0 );

exit:
    mbedtls_ctr_drbg_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE */
void ctr_drbg_validate_no_reseed( char *add_init_string, char *entropy_string,
                                  char *add1_string, char *add2_string,
                                  char *result_string )
{
    test_suite_ctr_drbg_validate( RESEED_NEVER, add_init_string,
                                  strlen( entropy_string ) / 2, entropy_string,
                                  "", add1_string, add2_string,
                                  result_string );
    goto exit;
}
/* END_CASE */

/* BEGIN_CASE */
void ctr_drbg_validate_pr( char *add_init_string, char *entropy_string,
                           char *add1_string, char *add2_string,
                           char *result_string )
{
    test_suite_ctr_drbg_validate( RESEED_ALWAYS, add_init_string,
                                  strlen( entropy_string ) / 6, entropy_string,
                                  "", add1_string, add2_string,
                                  result_string );
    goto exit;
}
/* END_CASE */

/* BEGIN_CASE */
void ctr_drbg_validate_nopr( data_t * add_init, data_t * entropy,
                             data_t * add1, data_t * add_reseed,
                             char *add2_string, char *result_string )
{
    test_suite_ctr_drbg_validate( RESEED_SECOND, add_init_string,
                                  strlen( entropy_string ) / 4, entropy_string,
                                  add_reseed_string, add1_string, add2_string,
                                  result_string );
    goto exit;
}
/* END_CASE */

/* BEGIN_CASE */
void ctr_drbg_entropy_usage(  )
{
    unsigned char out[16];
    unsigned char add[16];
    unsigned char entropy[1024];
    mbedtls_ctr_drbg_context ctx;
    size_t i, reps = 10;
    size_t last_idx;

    mbedtls_ctr_drbg_init( &ctx );
    test_offset_idx = 0;
    test_max_idx = sizeof( entropy );
    memset( entropy, 0, sizeof( entropy ) );
    memset( out, 0, sizeof( out ) );
    memset( add, 0, sizeof( add ) );

    /* Init must use entropy */
    last_idx = test_offset_idx;
    TEST_ASSERT( mbedtls_ctr_drbg_seed( &ctx, mbedtls_test_entropy_func, entropy, NULL, 0 ) == 0 );
    TEST_ASSERT( last_idx < test_offset_idx );

    /* By default, PR is off and reseed_interval is large,
     * so the next few calls should not use entropy */
    last_idx = test_offset_idx;
    for( i = 0; i < reps; i++ )
    {
        TEST_ASSERT( mbedtls_ctr_drbg_random( &ctx, out, sizeof( out ) - 4 ) == 0 );
        TEST_ASSERT( mbedtls_ctr_drbg_random_with_add( &ctx, out, sizeof( out ) - 4,
                                                add, sizeof( add ) ) == 0 );
    }
    TEST_ASSERT( last_idx == test_offset_idx );

    /* While at it, make sure we didn't write past the requested length */
    TEST_ASSERT( out[sizeof( out ) - 4] == 0 );
    TEST_ASSERT( out[sizeof( out ) - 3] == 0 );
    TEST_ASSERT( out[sizeof( out ) - 2] == 0 );
    TEST_ASSERT( out[sizeof( out ) - 1] == 0 );

    /* Set reseed_interval to the number of calls done,
     * so the next call should reseed */
    mbedtls_ctr_drbg_set_reseed_interval( &ctx, 2 * reps );
    TEST_ASSERT( mbedtls_ctr_drbg_random( &ctx, out, sizeof( out ) ) == 0 );
    TEST_ASSERT( last_idx < test_offset_idx );

    /* The new few calls should not reseed */
    last_idx = test_offset_idx;
    for( i = 0; i < reps / 2; i++ )
    {
        TEST_ASSERT( mbedtls_ctr_drbg_random( &ctx, out, sizeof( out ) ) == 0 );
        TEST_ASSERT( mbedtls_ctr_drbg_random_with_add( &ctx, out, sizeof( out ) ,
                                                add, sizeof( add ) ) == 0 );
    }
    TEST_ASSERT( last_idx == test_offset_idx );

    /* Call update with too much data (sizeof entropy > MAX(_SEED)_INPUT)
     * (just make sure it doesn't cause memory corruption) */
    mbedtls_ctr_drbg_update( &ctx, entropy, sizeof( entropy ) );

    /* Now enable PR, so the next few calls should all reseed */
    mbedtls_ctr_drbg_set_prediction_resistance( &ctx, MBEDTLS_CTR_DRBG_PR_ON );
    TEST_ASSERT( mbedtls_ctr_drbg_random( &ctx, out, sizeof( out ) ) == 0 );
    TEST_ASSERT( last_idx < test_offset_idx );

    /* Finally, check setting entropy_len */
    mbedtls_ctr_drbg_set_entropy_len( &ctx, 42 );
    last_idx = test_offset_idx;
    TEST_ASSERT( mbedtls_ctr_drbg_random( &ctx, out, sizeof( out ) ) == 0 );
    TEST_ASSERT( test_offset_idx - last_idx == 42 );

    mbedtls_ctr_drbg_set_entropy_len( &ctx, 13 );
    last_idx = test_offset_idx;
    TEST_ASSERT( mbedtls_ctr_drbg_random( &ctx, out, sizeof( out ) ) == 0 );
    TEST_ASSERT( test_offset_idx - last_idx == 13 );

exit:
    mbedtls_ctr_drbg_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_FS_IO */
void ctr_drbg_seed_file( char * path, int ret )
{
    mbedtls_ctr_drbg_context ctx;

    mbedtls_ctr_drbg_init( &ctx );

    TEST_ASSERT( mbedtls_ctr_drbg_seed( &ctx, rnd_std_rand, NULL, NULL, 0 ) == 0 );
    TEST_ASSERT( mbedtls_ctr_drbg_write_seed_file( &ctx, path ) == ret );
    TEST_ASSERT( mbedtls_ctr_drbg_update_seed_file( &ctx, path ) == ret );

exit:
    mbedtls_ctr_drbg_free( &ctx );
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_SELF_TEST */
void ctr_drbg_selftest(  )
{
    TEST_ASSERT( mbedtls_ctr_drbg_self_test( 1 ) == 0 );
}
/* END_CASE */