// SPDX-License-Identifier: GPL-2.0-or-later

/* fuzz.c - AFL++ fuzzing support: deterministic wrappers for
 *          clock_gettime() and getsockopt()
 *
 * Copyright Red Hat
 * Author: Anshu Kumari <anskuma@redhat.com>
 */

#include <string.h>
#include <time.h>
#include <errno.h>
#include <netinet/tcp.h>
#include "passt.h"
#include "fuzz.h"

/* Undo macros so definitions here call the real syscalls */
#undef clock_gettime
#undef getsockopt

#define FUZZ_CLOCK_BASE_SEC	10000

static struct timespec fuzz_clock;

/**
 * fuzz_clock_reset() - Reset clock to fixed baseline
 *
 * Called at the start of every __AFL_LOOP iteration so
 * the clock is identical regardless of iteration number.
 */
void fuzz_clock_reset(void)
{
	fuzz_clock.tv_sec = FUZZ_CLOCK_BASE_SEC;
	fuzz_clock.tv_nsec = 0;
}

/**
 * fuzz_clock_gettime() - Return deterministic time
 * @clk:	Clock ID
 * @tp:		Output timespec
 *
 * Return: 0 (always succeeds)
 */
int fuzz_clock_gettime(clockid_t clk, struct timespec *tp)
{
	(void)clk;
	*tp = fuzz_clock;

	/* increment the timestamp by 1 micro sec monotonically */
	fuzz_clock.tv_nsec += 1000;
	if (fuzz_clock.tv_nsec >= 1000000000) {
		fuzz_clock.tv_sec++;
		fuzz_clock.tv_nsec -= 1000000000;
	}
	return 0;
}

/**
 * fuzz_getsockopt() - Deterministic getsockopt wrapper
 * @fd:		Socket file descriptor
 * @level:	Protocol level
 * @optname:	Option name
 * @optval:	Output buffer
 * @optlen:	In/out option length
 *
 * For TCP_INFO: populates optval from the AFL++ shared memory buffer.
 * For SO_RCVBUF, SO_SNDBUF: returns deterministic values.
 *
 * Return: 0 on success, -1 on error
 */
int fuzz_getsockopt(int fd, int level, int optname, void *optval,
		    socklen_t *optlen)
{
	if (level == SOL_SOCKET) {
		if (optname == SO_RCVBUF || optname == SO_SNDBUF) {
			*(int *)optval = 212992; /* default linux buff size */
			*optlen = sizeof(int);
			return 0;
		}
	}

	if (level == SOL_TCP && optname == TCP_INFO) {
		size_t fill = *optlen;
		size_t copy_len;

		memset(optval, 0, fill);

		if (fuzz_sockopt_data && fuzz_sockopt_data_len > 0) {
			copy_len = MIN(fill, (size_t)fuzz_sockopt_data_len);
			memcpy(optval, fuzz_sockopt_data, copy_len);
			fuzz_sockopt_data += copy_len;
			fuzz_sockopt_data_len -= copy_len;
			*optlen = copy_len;
		} else {
			*optlen = 0;
		}

		return 0;
	}

	return getsockopt(fd, level, optname, optval, optlen);
}