/*      $OpenBSD: test_sshbuf_fuzz.c,v 1.5 2026/03/06 06:57:33 dtucker Exp $ */
/*
 * Regress test for sshbuf.h buffer API
 *
 * Placed in the public domain
 */

#include <sys/types.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include "test_helper.h"

#include "ssherr.h"
#include "sshbuf.h"

#define NUM_FUZZ_TESTS (1 << 18)

void sshbuf_fuzz_tests(void);

void
sshbuf_fuzz_tests(void)
{
        struct sshbuf *p1;
        u_char *dp;
        size_t sz, sz2, i, ntests = NUM_FUZZ_TESTS;
        uint32_t r;
        int ret;

        if (test_is_fast())
                ntests >>= 2;
        if (test_is_slow())
                ntests <<= 2;

        /* NB. uses sshbuf internals */
        TEST_START("fuzz alloc/dealloc");
        p1 = sshbuf_new();
        ASSERT_INT_EQ(sshbuf_set_max_size(p1, 16 * 1024), 0);
        ASSERT_PTR_NE(p1, NULL);
        ASSERT_PTR_NE(sshbuf_ptr(p1), NULL);
        ASSERT_MEM_ZERO_NE(sshbuf_ptr(p1), sshbuf_len(p1));
        for (i = 0; i < ntests; i++) {
                r = arc4random_uniform(10);
                if (r == 0) {
                        /* 10% chance: small reserve */
                        r = arc4random_uniform(10);
 fuzz_reserve:
                        sz = sshbuf_avail(p1);
                        sz2 = sshbuf_len(p1);
                        ret = sshbuf_reserve(p1, r, &dp);
                        if (ret < 0) {
                                ASSERT_PTR_EQ(dp, NULL);
                                ASSERT_SIZE_T_LT(sz, r);
                                ASSERT_SIZE_T_EQ(sshbuf_avail(p1), sz);
                                ASSERT_SIZE_T_EQ(sshbuf_len(p1), sz2);
                        } else {
                                ASSERT_PTR_NE(dp, NULL);
                                ASSERT_SIZE_T_GE(sz, r);
                                ASSERT_SIZE_T_EQ(sshbuf_avail(p1), sz - r);
                                ASSERT_SIZE_T_EQ(sshbuf_len(p1), sz2 + r);
                                memset(dp, arc4random_uniform(255) + 1, r);
                        }
                } else if (r < 3) {
                        /* 20% chance: big reserve */
                        r = arc4random_uniform(8 * 1024);
                        goto fuzz_reserve;
                } else if (r == 3) {
                        /* 10% chance: small consume */
                        r = arc4random_uniform(10);
 fuzz_consume:
                        sz = sshbuf_avail(p1);
                        sz2 = sshbuf_len(p1);
                        /* 50% change consume from end, otherwise start */
                        ret = ((arc4random() & 1) ?
                            sshbuf_consume : sshbuf_consume_end)(p1, r);
                        if (ret < 0) {
                                ASSERT_SIZE_T_LT(sz2, r);
                                ASSERT_SIZE_T_EQ(sshbuf_avail(p1), sz);
                                ASSERT_SIZE_T_EQ(sshbuf_len(p1), sz2);
                        } else {
                                ASSERT_SIZE_T_GE(sz2, r);
                                ASSERT_SIZE_T_EQ(sshbuf_avail(p1), sz + r);
                                ASSERT_SIZE_T_EQ(sshbuf_len(p1), sz2 - r);
                        }
                } else if (r < 8) {
                        /* 40% chance: big consume */
                        r = arc4random_uniform(2 * 1024);
                        goto fuzz_consume;
                } else if (r == 8) {
                        /* 10% chance: reset max size */
                        r = arc4random_uniform(16 * 1024);
                        sz = sshbuf_max_size(p1);
                        if (sshbuf_set_max_size(p1, r) < 0)
                                ASSERT_SIZE_T_EQ(sshbuf_max_size(p1), sz);
                        else
                                ASSERT_SIZE_T_EQ(sshbuf_max_size(p1), r);
                } else {
                        if (arc4random_uniform(8192) == 0) {
                                /* tiny chance: new buffer */
                                ASSERT_PTR_NE(sshbuf_ptr(p1), NULL);
                                ASSERT_MEM_ZERO_NE(sshbuf_ptr(p1), sshbuf_len(p1));
                                sshbuf_free(p1);
                                p1 = sshbuf_new();
                                ASSERT_PTR_NE(p1, NULL);
                                ASSERT_INT_EQ(sshbuf_set_max_size(p1,
                                    16 * 1024), 0);
                        } else {
                                /* Almost 10%: giant reserve */
                                /* use arc4random_buf for r > 2^32 on 64 bit */
                                arc4random_buf(&r, sizeof(r));
                                while (r < SSHBUF_SIZE_MAX / 2) {
                                        r <<= 1;
                                        r |= arc4random() & 1;
                                }
                                goto fuzz_reserve;
                        }
                }
                ASSERT_PTR_NE(sshbuf_ptr(p1), NULL);
                ASSERT_SIZE_T_LE(sshbuf_max_size(p1), 16 * 1024);
        }
        ASSERT_PTR_NE(sshbuf_ptr(p1), NULL);
        ASSERT_MEM_ZERO_NE(sshbuf_ptr(p1), sshbuf_len(p1));
        sshbuf_free(p1);
        TEST_DONE();
}