xref: /third_party/mbedtls/programs/fuzz/common.c (revision a8e1175b) 
1#include "common.h"
2#include <limits.h>
3#include <stdio.h>
4#include <string.h>
5#include <stdlib.h>
6#include "mbedtls/ctr_drbg.h"
7
8#if defined(MBEDTLS_PLATFORM_TIME_ALT)
9mbedtls_time_t dummy_constant_time(mbedtls_time_t *time)
10{
11    (void) time;
12    return 0x5af2a056;
13}
14#endif
15
16void dummy_init(void)
17{
18#if defined(MBEDTLS_PLATFORM_TIME_ALT)
19    mbedtls_platform_set_time(dummy_constant_time);
20#else
21    fprintf(stderr, "Warning: fuzzing without constant time\n");
22#endif
23}
24
25int dummy_send(void *ctx, const unsigned char *buf, size_t len)
26{
27    //silence warning about unused parameter
28    (void) ctx;
29    (void) buf;
30
31    //pretends we wrote everything ok
32    if (len > INT_MAX) {
33        return -1;
34    }
35    return (int) len;
36}
37
38int fuzz_recv(void *ctx, unsigned char *buf, size_t len)
39{
40    //reads from the buffer from fuzzer
41    fuzzBufferOffset_t *biomemfuzz = (fuzzBufferOffset_t *) ctx;
42
43    if (biomemfuzz->Offset == biomemfuzz->Size) {
44        //EOF
45        return 0;
46    }
47    if (len > INT_MAX) {
48        return -1;
49    }
50    if (len + biomemfuzz->Offset > biomemfuzz->Size) {
51        //do not overflow
52        len = biomemfuzz->Size - biomemfuzz->Offset;
53    }
54    memcpy(buf, biomemfuzz->Data + biomemfuzz->Offset, len);
55    biomemfuzz->Offset += len;
56    return (int) len;
57}
58
59int dummy_random(void *p_rng, unsigned char *output, size_t output_len)
60{
61    int ret;
62    size_t i;
63
64#if defined(MBEDTLS_CTR_DRBG_C)
65    //mbedtls_ctr_drbg_random requires a valid mbedtls_ctr_drbg_context in p_rng
66    if (p_rng != NULL) {
67        //use mbedtls_ctr_drbg_random to find bugs in it
68        ret = mbedtls_ctr_drbg_random(p_rng, output, output_len);
69    } else {
70        //fall through to pseudo-random
71        ret = 0;
72    }
73#else
74    (void) p_rng;
75    ret = 0;
76#endif
77    for (i = 0; i < output_len; i++) {
78        //replace result with pseudo random
79        output[i] = (unsigned char) rand();
80    }
81    return ret;
82}
83
84int dummy_entropy(void *data, unsigned char *output, size_t len)
85{
86    size_t i;
87    (void) data;
88
89    //use mbedtls_entropy_func to find bugs in it
90    //test performance impact of entropy
91    //ret = mbedtls_entropy_func(data, output, len);
92    for (i = 0; i < len; i++) {
93        //replace result with pseudo random
94        output[i] = (unsigned char) rand();
95    }
96    return 0;
97}
98
99int fuzz_recv_timeout(void *ctx, unsigned char *buf, size_t len,
100                      uint32_t timeout)
101{
102    (void) timeout;
103
104    return fuzz_recv(ctx, buf, len);
105}
106