/* main.c - Application main entry point */

/*
 * Copyright (c) 2015 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/types.h>
#include <stddef.h>
#include <string.h>
#include <zephyr/sys/printk.h>

#include <zephyr/net/buf.h>

#include <zephyr/ztest.h>

#define TEST_TIMEOUT K_SECONDS(1)

#define USER_DATA_HEAP	4
#define USER_DATA_FIXED	0
#define USER_DATA_VAR	63
#define FIXED_BUFFER_SIZE 128

struct bt_data {
	void *hci_sync;

	union {
		uint16_t hci_opcode;
		uint16_t acl_handle;
	};

	uint8_t type;
};

struct in6_addr {
	union {
		uint8_t u6_addr8[16];
		uint16_t u6_addr16[8];          /* In big endian */
		uint32_t u6_addr32[4];          /* In big endian */
	} in6_u;
#define s6_addr         in6_u.u6_addr8
#define s6_addr16       in6_u.u6_addr16
#define s6_addr32       in6_u.u6_addr32
};

struct ipv6_hdr {
	uint8_t vtc;
	uint8_t tcflow;
	uint16_t flow;
	uint8_t len[2];
	uint8_t nexthdr;
	uint8_t hop_limit;
	struct in6_addr src;
	struct in6_addr dst;
} __attribute__((__packed__));

struct udp_hdr {
	uint16_t src_port;
	uint16_t dst_port;
	uint16_t len;
	uint16_t chksum;
} __attribute__((__packed__));

static int destroy_called;

static void buf_destroy(struct net_buf *buf);
static void fixed_destroy(struct net_buf *buf);
static void var_destroy(struct net_buf *buf);

NET_BUF_POOL_HEAP_DEFINE(bufs_pool, 10, USER_DATA_HEAP, buf_destroy);
NET_BUF_POOL_FIXED_DEFINE(fixed_pool, 10, FIXED_BUFFER_SIZE, USER_DATA_FIXED, fixed_destroy);
NET_BUF_POOL_VAR_DEFINE(var_pool, 10, 1024, USER_DATA_VAR, var_destroy);

static void buf_destroy(struct net_buf *buf)
{
	struct net_buf_pool *pool = net_buf_pool_get(buf->pool_id);

	destroy_called++;
	zassert_equal(pool, &bufs_pool, "Invalid free pointer in buffer");
	net_buf_destroy(buf);
}

static void fixed_destroy(struct net_buf *buf)
{
	struct net_buf_pool *pool = net_buf_pool_get(buf->pool_id);

	destroy_called++;
	zassert_equal(pool, &fixed_pool, "Invalid free pointer in buffer");
	net_buf_destroy(buf);
}

static void var_destroy(struct net_buf *buf)
{
	struct net_buf_pool *pool = net_buf_pool_get(buf->pool_id);

	destroy_called++;
	zassert_equal(pool, &var_pool, "Invalid free pointer in buffer");
	net_buf_destroy(buf);
}

static const char example_data[] = "0123456789"
				   "abcdefghijklmnopqrstuvxyz"
				   "!#¤%&/()=?";

ZTEST(net_buf_tests, test_net_buf_1)
{
	struct net_buf *bufs[bufs_pool.buf_count];
	struct net_buf *buf;
	int i;

	for (i = 0; i < bufs_pool.buf_count; i++) {
		buf = net_buf_alloc_len(&bufs_pool, 74, K_NO_WAIT);
		zassert_not_null(buf, "Failed to get buffer");
		bufs[i] = buf;
	}

	for (i = 0; i < ARRAY_SIZE(bufs); i++) {
		net_buf_unref(bufs[i]);
	}

	zassert_equal(destroy_called, ARRAY_SIZE(bufs),
		      "Incorrect destroy callback count");
}

ZTEST(net_buf_tests, test_net_buf_2)
{
	struct net_buf *frag, *head;
	static struct k_fifo fifo;
	int i;

	head = net_buf_alloc_len(&bufs_pool, 74, K_NO_WAIT);
	zassert_not_null(head, "Failed to get fragment list head");

	frag = head;
	for (i = 0; i < bufs_pool.buf_count - 1; i++) {
		frag->frags = net_buf_alloc_len(&bufs_pool, 74, K_NO_WAIT);
		zassert_not_null(frag->frags, "Failed to get fragment");
		frag = frag->frags;
	}

	k_fifo_init(&fifo);
	net_buf_put(&fifo, head);
	head = net_buf_get(&fifo, K_NO_WAIT);

	destroy_called = 0;
	net_buf_unref(head);
	zassert_equal(destroy_called, bufs_pool.buf_count,
		      "Incorrect fragment destroy callback count");
}

static void test_3_thread(void *arg1, void *arg2, void *arg3)
{
	ARG_UNUSED(arg3);

	struct k_fifo *fifo = (struct k_fifo *)arg1;
	struct k_sem *sema = (struct k_sem *)arg2;
	struct net_buf *buf;

	k_sem_give(sema);

	buf = net_buf_get(fifo, TEST_TIMEOUT);
	zassert_not_null(buf, "Unable to get buffer");

	destroy_called = 0;
	net_buf_unref(buf);
	zassert_equal(destroy_called, bufs_pool.buf_count,
		      "Incorrect destroy callback count");

	k_sem_give(sema);
}

static K_THREAD_STACK_DEFINE(test_3_thread_stack, 1024);

ZTEST(net_buf_tests, test_net_buf_3)
{
	static struct k_thread test_3_thread_data;
	struct net_buf *frag, *head;
	static struct k_fifo fifo;
	static struct k_sem sema;
	int i;

	head = net_buf_alloc_len(&bufs_pool, 74, K_NO_WAIT);
	zassert_not_null(head, "Failed to get fragment list head");

	frag = head;
	for (i = 0; i < bufs_pool.buf_count - 1; i++) {
		frag->frags = net_buf_alloc_len(&bufs_pool, 74, K_NO_WAIT);
		zassert_not_null(frag->frags, "Failed to get fragment");
		frag = frag->frags;
	}

	k_fifo_init(&fifo);
	k_sem_init(&sema, 0, UINT_MAX);

	k_thread_create(&test_3_thread_data, test_3_thread_stack,
			K_THREAD_STACK_SIZEOF(test_3_thread_stack),
			test_3_thread, &fifo, &sema, NULL,
			K_PRIO_COOP(7), 0, K_NO_WAIT);

	zassert_true(k_sem_take(&sema, TEST_TIMEOUT) == 0,
		     "Timeout while waiting for semaphore");

	net_buf_put(&fifo, head);

	zassert_true(k_sem_take(&sema, TEST_TIMEOUT) == 0,
		     "Timeout while waiting for semaphore");
}

ZTEST(net_buf_tests, test_net_buf_4)
{
	struct net_buf *frags[bufs_pool.buf_count - 1];
	struct net_buf *buf, *frag;
	int i, removed;

	destroy_called = 0;

	/* Create a buf that does not have any data to store, it just
	 * contains link to fragments.
	 */
	buf = net_buf_alloc_len(&bufs_pool, 0, K_FOREVER);

	zassert_equal(buf->size, 0, "Invalid buffer size");

	/* Test the fragments by appending after last fragment */
	for (i = 0; i < bufs_pool.buf_count - 2; i++) {
		frag = net_buf_alloc_len(&bufs_pool, 74, K_FOREVER);
		net_buf_frag_add(buf, frag);
		frags[i] = frag;
	}

	/* And one as a first fragment */
	frag = net_buf_alloc_len(&bufs_pool, 74, K_FOREVER);
	net_buf_frag_insert(buf, frag);
	frags[i] = frag;

	frag = buf->frags;

	i = 0;
	while (frag) {
		frag = frag->frags;
		i++;
	}

	zassert_equal(i, bufs_pool.buf_count - 1, "Incorrect fragment count");

	/* Remove about half of the fragments and verify count */
	i = removed = 0;
	frag = buf->frags;
	while (frag) {
		struct net_buf *next = frag->frags;

		if ((i % 2) && next) {
			net_buf_frag_del(frag, next);
			net_buf_unref(next);
			removed++;
		} else {
			frag = next;
		}
		i++;
	}

	i = 0;
	frag = buf->frags;
	while (frag) {
		frag = frag->frags;
		i++;
	}

	zassert_equal(1 + i + removed, bufs_pool.buf_count,
		      "Incorrect removed fragment count");

	removed = 0;

	while (buf->frags) {
		struct net_buf *frag2 = buf->frags;

		net_buf_frag_del(buf, frag2);
		net_buf_unref(frag2);
		removed++;
	}

	zassert_equal(removed, i, "Incorrect removed fragment count");
	zassert_equal(destroy_called, bufs_pool.buf_count - 1,
		      "Incorrect frag destroy callback count");

	/* Add the fragments back and verify that they are properly unref
	 * by freeing the top buf.
	 */
	for (i = 0; i < bufs_pool.buf_count - 4; i++) {
		net_buf_frag_add(buf,
				 net_buf_alloc_len(&bufs_pool, 74, K_FOREVER));
	}

	/* Create a fragment list and add it to frags list after first
	 * element
	 */
	frag = net_buf_alloc_len(&bufs_pool, 74, K_FOREVER);
	net_buf_frag_add(frag, net_buf_alloc_len(&bufs_pool, 74, K_FOREVER));
	net_buf_frag_insert(frag, net_buf_alloc_len(&bufs_pool, 74, K_FOREVER));
	net_buf_frag_insert(buf->frags->frags, frag);

	i = 0;
	frag = buf->frags;
	while (frag) {
		frag = frag->frags;
		i++;
	}

	zassert_equal(i, bufs_pool.buf_count - 1, "Incorrect fragment count");

	destroy_called = 0;

	net_buf_unref(buf);

	zassert_equal(destroy_called, bufs_pool.buf_count,
		      "Incorrect frag destroy callback count");
}

ZTEST(net_buf_tests, test_net_buf_big_buf)
{
	struct net_buf *big_frags[bufs_pool.buf_count];
	struct net_buf *buf, *frag;
	struct ipv6_hdr *ipv6;
	struct udp_hdr *udp;
	int i, len;

	destroy_called = 0;

	buf = net_buf_alloc_len(&bufs_pool, 0, K_FOREVER);

	/* We reserve some space in front of the buffer for protocol
	 * headers (IPv6 + UDP). Link layer headers are ignored in
	 * this example.
	 */
#define PROTO_HEADERS (sizeof(struct ipv6_hdr) + sizeof(struct udp_hdr))
	frag = net_buf_alloc_len(&bufs_pool, 1280, K_FOREVER);
	net_buf_reserve(frag, PROTO_HEADERS);
	big_frags[0] = frag;

	/* First add some application data */
	len = strlen(example_data);
	for (i = 0; i < 2; i++) {
		zassert_true(net_buf_tailroom(frag) >= len,
			     "Allocated buffer is too small");
		memcpy(net_buf_add(frag, len), example_data, len);
	}

	ipv6 = (struct ipv6_hdr *)(frag->data - net_buf_headroom(frag));
	udp = (struct udp_hdr *)((uint8_t *)ipv6 + sizeof(*ipv6));

	net_buf_frag_add(buf, frag);
	net_buf_unref(buf);

	zassert_equal(destroy_called, 2, "Incorrect destroy callback count");
}

ZTEST(net_buf_tests, test_net_buf_multi_frags)
{
	struct net_buf *frags[bufs_pool.buf_count];
	struct net_buf *buf;
	struct ipv6_hdr *ipv6;
	struct udp_hdr *udp;
	int i, len, avail = 0, occupied = 0;

	destroy_called = 0;

	/* Example of multi fragment scenario with IPv6 */
	buf = net_buf_alloc_len(&bufs_pool, 0, K_FOREVER);

	/* We reserve some space in front of the buffer for link layer headers.
	 * In this example, we use min MTU (81 bytes) defined in rfc 4944 ch. 4
	 *
	 * Note that with IEEE 802.15.4 we typically cannot have zero-copy
	 * in sending side because of the IPv6 header compression.
	 */

#define LL_HEADERS (127 - 81)
	for (i = 0; i < bufs_pool.buf_count - 2; i++) {
		frags[i] = net_buf_alloc_len(&bufs_pool, 128, K_FOREVER);
		net_buf_reserve(frags[i], LL_HEADERS);
		avail += net_buf_tailroom(frags[i]);
		net_buf_frag_add(buf, frags[i]);
	}

	/* Place the IP + UDP header in the first fragment */
	frags[i] = net_buf_alloc_len(&bufs_pool, 128, K_FOREVER);
	net_buf_reserve(frags[i], LL_HEADERS + (sizeof(struct ipv6_hdr) +
						sizeof(struct udp_hdr)));
	avail += net_buf_tailroom(frags[i]);
	net_buf_frag_insert(buf, frags[i]);

	/* First add some application data */
	len = strlen(example_data);
	for (i = 0; i < bufs_pool.buf_count - 2; i++) {
		zassert_true(net_buf_tailroom(frags[i]) >= len,
			     "Allocated buffer is too small");
		memcpy(net_buf_add(frags[i], len), example_data, len);
		occupied += frags[i]->len;
	}

	ipv6 = (struct ipv6_hdr *)(frags[i]->data - net_buf_headroom(frags[i]));
	udp = (struct udp_hdr *)((uint8_t *)ipv6 + sizeof(*ipv6));

	net_buf_unref(buf);

	zassert_equal(destroy_called, bufs_pool.buf_count,
		      "Incorrect frag destroy callback count");
}

ZTEST(net_buf_tests, test_net_buf_clone_ref_count)
{
	struct net_buf *buf, *clone;

	destroy_called = 0;

	/* Heap pool supports reference counting */
	buf = net_buf_alloc_len(&bufs_pool, 74, K_NO_WAIT);
	zassert_not_null(buf, "Failed to get buffer");

	clone = net_buf_clone(buf, K_NO_WAIT);
	zassert_not_null(clone, "Failed to get clone buffer");
	zassert_equal(buf->data, clone->data, "Incorrect clone data pointer");

	net_buf_unref(buf);
	net_buf_unref(clone);

	zassert_equal(destroy_called, 2, "Incorrect destroy callback count");
}

ZTEST(net_buf_tests, test_net_buf_clone_no_ref_count)
{
	struct net_buf *buf, *clone;
	const uint8_t data[3] = {0x11, 0x22, 0x33};

	destroy_called = 0;

	/* Fixed pool does not support reference counting */
	buf = net_buf_alloc_len(&fixed_pool, 3, K_NO_WAIT);
	zassert_not_null(buf, "Failed to get buffer");
	net_buf_add_mem(buf, data, sizeof(data));

	clone = net_buf_clone(buf, K_NO_WAIT);
	zassert_not_null(clone, "Failed to get clone buffer");
	zassert_not_equal(buf->data, clone->data,
			  "No reference counting support, different pointers expected");
	zassert_mem_equal(clone->data, data, sizeof(data));

	net_buf_unref(buf);
	net_buf_unref(clone);

	zassert_equal(destroy_called, 2, "Incorrect destroy callback count");
}

/* Regression test: Zero sized buffers must be copy-able, not trigger a NULL pointer dereference */
ZTEST(net_buf_tests, test_net_buf_clone_reference_counted_zero_sized_buffer)
{
	struct net_buf *buf, *clone;

	buf = net_buf_alloc_len(&var_pool, 0, K_NO_WAIT);
	zassert_not_null(buf, "Failed to get buffer");

	clone = net_buf_clone(buf, K_NO_WAIT);
	zassert_not_null(clone, "Failed to clone zero sized buffer");

	net_buf_unref(buf);
}

ZTEST(net_buf_tests, test_net_buf_clone_user_data)
{
	struct net_buf *original, *clone;
	uint32_t *buf_user_data, *clone_user_data;

	/* Requesting size 1 because all we are interested in are the user data */
	original = net_buf_alloc_len(&bufs_pool, 1, K_NO_WAIT);
	zassert_not_null(original, "Failed to get buffer");
	buf_user_data = net_buf_user_data(original);
	*buf_user_data = 0xAABBCCDD;

	clone = net_buf_clone(original, K_NO_WAIT);
	zassert_not_null(clone, "Failed to get clone buffer");
	clone_user_data = net_buf_user_data(clone);
	zexpect_equal(*clone_user_data, 0xAABBCCDD, "User data copy is invalid");

	net_buf_unref(original);
	net_buf_unref(clone);
}

ZTEST(net_buf_tests, test_net_buf_fixed_pool)
{
	struct net_buf *buf;

	destroy_called = 0;

	buf = net_buf_alloc_len(&fixed_pool, 20, K_NO_WAIT);
	zassert_not_null(buf, "Failed to get buffer");

	/* Verify buffer's size and len - even though we requested less bytes we
	 * should get a buffer with the fixed size.
	 */
	zassert_equal(buf->size, FIXED_BUFFER_SIZE, "Invalid fixed buffer size");
	zassert_equal(buf->len, 0, "Invalid fixed buffer length");

	net_buf_unref(buf);

	zassert_equal(destroy_called, 1, "Incorrect destroy callback count");
}

ZTEST(net_buf_tests, test_net_buf_var_pool)
{
	struct net_buf *buf1, *buf2, *buf3;

	destroy_called = 0;

	buf1 = net_buf_alloc_len(&var_pool, 20, K_NO_WAIT);
	zassert_not_null(buf1, "Failed to get buffer");

	buf2 = net_buf_alloc_len(&var_pool, 200, K_NO_WAIT);
	zassert_not_null(buf2, "Failed to get buffer");

	buf3 = net_buf_clone(buf2, K_NO_WAIT);
	zassert_not_null(buf3, "Failed to clone buffer");
	zassert_equal(buf3->data, buf2->data, "Cloned data doesn't match");

	net_buf_unref(buf1);
	net_buf_unref(buf2);
	net_buf_unref(buf3);

	zassert_equal(destroy_called, 3, "Incorrect destroy callback count");
}

ZTEST(net_buf_tests, test_net_buf_byte_order)
{
	struct net_buf *buf;
	uint8_t le16[2] = { 0x02, 0x01 };
	uint8_t be16[2] = { 0x01, 0x02 };
	uint8_t le24[3] = { 0x03, 0x02, 0x01 };
	uint8_t be24[3] = { 0x01, 0x02, 0x03 };
	uint8_t le32[4] = { 0x04, 0x03, 0x02, 0x01 };
	uint8_t be32[4] = { 0x01, 0x02, 0x03, 0x04 };
	uint8_t le40[5] = { 0x05, 0x04, 0x03, 0x02, 0x01 };
	uint8_t be40[5] = { 0x01, 0x02, 0x03, 0x04, 0x05 };
	uint8_t le48[6] = { 0x06, 0x05, 0x04, 0x03, 0x02, 0x01 };
	uint8_t be48[6] = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06 };
	uint8_t le64[8] = { 0x08, 0x07, 0x06, 0x05, 0x04, 0x03, 0x02, 0x01 };
	uint8_t be64[8] = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 };
	uint16_t u16;
	uint32_t u32;
	uint64_t u64;

	buf = net_buf_alloc_len(&fixed_pool, 16, K_FOREVER);
	zassert_not_null(buf, "Failed to get buffer");

	/* add/pull byte order */
	net_buf_add_mem(buf, &le16, sizeof(le16));
	net_buf_add_mem(buf, &be16, sizeof(be16));

	u16 = net_buf_pull_le16(buf);
	zassert_equal(u16, net_buf_pull_be16(buf),
		      "Invalid 16 bits byte order");

	net_buf_reset(buf);

	net_buf_add_le16(buf, u16);
	net_buf_add_be16(buf, u16);

	zassert_mem_equal(le16, net_buf_pull_mem(buf, sizeof(le16)),
			  sizeof(le16), "Invalid 16 bits byte order");
	zassert_mem_equal(be16, net_buf_pull_mem(buf, sizeof(be16)),
			  sizeof(be16), "Invalid 16 bits byte order");

	net_buf_reset(buf);

	net_buf_add_mem(buf, &le24, sizeof(le24));
	net_buf_add_mem(buf, &be24, sizeof(be24));

	u32 = net_buf_pull_le24(buf);
	zassert_equal(u32, net_buf_pull_be24(buf),
		      "Invalid 24 bits byte order");

	net_buf_reset(buf);

	net_buf_add_le24(buf, u32);
	net_buf_add_be24(buf, u32);

	zassert_mem_equal(le24, net_buf_pull_mem(buf, sizeof(le24)),
			  sizeof(le24), "Invalid 24 bits byte order");
	zassert_mem_equal(be24, net_buf_pull_mem(buf, sizeof(be24)),
			  sizeof(be24), "Invalid 24 bits byte order");

	net_buf_reset(buf);

	net_buf_add_mem(buf, &le32, sizeof(le32));
	net_buf_add_mem(buf, &be32, sizeof(be32));

	u32 = net_buf_pull_le32(buf);
	zassert_equal(u32, net_buf_pull_be32(buf),
		      "Invalid 32 bits byte order");

	net_buf_reset(buf);

	net_buf_add_le32(buf, u32);
	net_buf_add_be32(buf, u32);

	zassert_mem_equal(le32, net_buf_pull_mem(buf, sizeof(le32)),
			  sizeof(le32), "Invalid 32 bits byte order");
	zassert_mem_equal(be32, net_buf_pull_mem(buf, sizeof(be32)),
			  sizeof(be32), "Invalid 32 bits byte order");

	net_buf_reset(buf);

	net_buf_add_mem(buf, &le40, sizeof(le40));
	net_buf_add_mem(buf, &be40, sizeof(be40));

	u64 = net_buf_pull_le40(buf);
	zassert_equal(u64, net_buf_pull_be40(buf), "Invalid 40 bits byte order");

	net_buf_reset(buf);

	net_buf_add_le40(buf, u64);
	net_buf_add_be40(buf, u64);

	zassert_mem_equal(le40, net_buf_pull_mem(buf, sizeof(le40)), sizeof(le40),
			  "Invalid 40 bits byte order");
	zassert_mem_equal(be40, net_buf_pull_mem(buf, sizeof(be40)), sizeof(be40),
			  "Invalid 40 bits byte order");

	net_buf_reset(buf);

	net_buf_add_mem(buf, &le48, sizeof(le48));
	net_buf_add_mem(buf, &be48, sizeof(be48));

	u64 = net_buf_pull_le48(buf);
	zassert_equal(u64, net_buf_pull_be48(buf),
		      "Invalid 48 bits byte order");

	net_buf_reset(buf);

	net_buf_add_le48(buf, u64);
	net_buf_add_be48(buf, u64);

	zassert_mem_equal(le48, net_buf_pull_mem(buf, sizeof(le48)),
			  sizeof(le48), "Invalid 48 bits byte order");
	zassert_mem_equal(be48, net_buf_pull_mem(buf, sizeof(be48)),
			  sizeof(be48), "Invalid 48 bits byte order");

	net_buf_reset(buf);

	net_buf_add_mem(buf, &le64, sizeof(le64));
	net_buf_add_mem(buf, &be64, sizeof(be64));

	u64 = net_buf_pull_le64(buf);
	zassert_equal(u64, net_buf_pull_be64(buf),
		      "Invalid 64 bits byte order");

	net_buf_reset(buf);

	net_buf_add_le64(buf, u64);
	net_buf_add_be64(buf, u64);

	zassert_mem_equal(le64, net_buf_pull_mem(buf, sizeof(le64)),
			  sizeof(le64), "Invalid 64 bits byte order");
	zassert_mem_equal(be64, net_buf_pull_mem(buf, sizeof(be64)),
			  sizeof(be64), "Invalid 64 bits byte order");

	/* push/remove byte order */
	net_buf_reset(buf);
	net_buf_reserve(buf, 16);

	net_buf_push_mem(buf, &le16, sizeof(le16));
	net_buf_push_mem(buf, &be16, sizeof(be16));

	u16 = net_buf_remove_le16(buf);
	zassert_equal(u16, net_buf_remove_be16(buf),
		      "Invalid 16 bits byte order");

	net_buf_reset(buf);
	net_buf_reserve(buf, 16);

	net_buf_push_le16(buf, u16);
	net_buf_push_be16(buf, u16);

	zassert_mem_equal(le16, net_buf_remove_mem(buf, sizeof(le16)),
			  sizeof(le16),  "Invalid 16 bits byte order");
	zassert_mem_equal(be16, net_buf_remove_mem(buf, sizeof(be16)),
			  sizeof(be16),  "Invalid 16 bits byte order");

	net_buf_reset(buf);
	net_buf_reserve(buf, 16);

	net_buf_push_mem(buf, &le24, sizeof(le24));
	net_buf_push_mem(buf, &be24, sizeof(be24));

	u32 = net_buf_remove_le24(buf);
	zassert_equal(u32, net_buf_remove_be24(buf),
		      "Invalid 24 bits byte order");

	net_buf_reset(buf);
	net_buf_reserve(buf, 16);

	net_buf_push_le24(buf, u32);
	net_buf_push_be24(buf, u32);

	zassert_mem_equal(le24, net_buf_remove_mem(buf, sizeof(le24)),
			  sizeof(le24),  "Invalid 24 bits byte order");
	zassert_mem_equal(be24, net_buf_remove_mem(buf, sizeof(be24)),
			  sizeof(be24),  "Invalid 24 bits byte order");

	net_buf_reset(buf);
	net_buf_reserve(buf, 16);

	net_buf_push_mem(buf, &le32, sizeof(le32));
	net_buf_push_mem(buf, &be32, sizeof(be32));

	u32 = net_buf_remove_le32(buf);
	zassert_equal(u32, net_buf_remove_be32(buf),
		      "Invalid 32 bits byte order");

	net_buf_reset(buf);
	net_buf_reserve(buf, 16);

	net_buf_push_le32(buf, u32);
	net_buf_push_be32(buf, u32);

	zassert_mem_equal(le32, net_buf_remove_mem(buf, sizeof(le32)),
			  sizeof(le32), "Invalid 32 bits byte order");
	zassert_mem_equal(be32, net_buf_remove_mem(buf, sizeof(be32)),
			  sizeof(be32), "Invalid 32 bits byte order");

	net_buf_reset(buf);
	net_buf_reserve(buf, 16);

	net_buf_push_mem(buf, &le40, sizeof(le40));
	net_buf_push_mem(buf, &be40, sizeof(be40));

	u64 = net_buf_remove_le40(buf);
	zassert_equal(u64, net_buf_remove_be40(buf), "Invalid 40 bits byte order");

	net_buf_reset(buf);
	net_buf_reserve(buf, 16);

	net_buf_push_le40(buf, u64);
	net_buf_push_be40(buf, u64);

	zassert_mem_equal(le40, net_buf_remove_mem(buf, sizeof(le40)), sizeof(le40),
			  "Invalid 40 bits byte order");
	zassert_mem_equal(be40, net_buf_remove_mem(buf, sizeof(be40)), sizeof(be40),
			  "Invalid 40 bits byte order");

	net_buf_reset(buf);
	net_buf_reserve(buf, 16);

	net_buf_push_mem(buf, &le48, sizeof(le48));
	net_buf_push_mem(buf, &be48, sizeof(be48));

	u64 = net_buf_remove_le48(buf);
	zassert_equal(u64, net_buf_remove_be48(buf),
		      "Invalid 48 bits byte order");

	net_buf_reset(buf);
	net_buf_reserve(buf, 16);

	net_buf_push_le48(buf, u64);
	net_buf_push_be48(buf, u64);

	zassert_mem_equal(le48, net_buf_remove_mem(buf, sizeof(le48)),
			  sizeof(le48),  "Invalid 48 bits byte order");
	zassert_mem_equal(be48, net_buf_remove_mem(buf, sizeof(be48)),
			  sizeof(be48),  "Invalid 48 bits byte order");

	net_buf_reset(buf);
	net_buf_reserve(buf, 16);

	net_buf_push_mem(buf, &le64, sizeof(le64));
	net_buf_push_mem(buf, &be64, sizeof(be64));

	u64 = net_buf_remove_le64(buf);
	zassert_equal(u64, net_buf_remove_be64(buf),
		      "Invalid 64 bits byte order");

	net_buf_reset(buf);
	net_buf_reserve(buf, 16);

	net_buf_push_le64(buf, u64);
	net_buf_push_be64(buf, u64);

	zassert_mem_equal(le64, net_buf_remove_mem(buf, sizeof(le64)),
			  sizeof(le64), "Invalid 64 bits byte order");
	zassert_mem_equal(be64, net_buf_remove_mem(buf, sizeof(be64)),
			  sizeof(be64), "Invalid 64 bits byte order");

	net_buf_unref(buf);
}

ZTEST(net_buf_tests, test_net_buf_user_data)
{
	struct net_buf *buf;

	/* Fixed Pool */
	buf = net_buf_alloc(&fixed_pool, K_NO_WAIT);
	zassert_not_null(buf, "Failed to get buffer");

	zassert_equal(USER_DATA_FIXED, fixed_pool.user_data_size,
		"Bad user_data_size");
	zassert_equal(USER_DATA_FIXED, buf->user_data_size,
		"Bad user_data_size");

	net_buf_unref(buf);

	/* Heap Pool */
	buf = net_buf_alloc_len(&bufs_pool, 20, K_NO_WAIT);
	zassert_not_null(buf, "Failed to get buffer");

	zassert_equal(USER_DATA_HEAP, bufs_pool.user_data_size,
		"Bad user_data_size");
	zassert_equal(USER_DATA_HEAP, buf->user_data_size,
		"Bad user_data_size");

	net_buf_unref(buf);

	/* Var Pool */
	buf = net_buf_alloc_len(&var_pool, 20, K_NO_WAIT);
	zassert_not_null(buf, "Failed to get buffer");

	zassert_equal(USER_DATA_VAR, var_pool.user_data_size,
		"Bad user_data_size");
	zassert_equal(USER_DATA_VAR, buf->user_data_size,
		"Bad user_data_size");

	net_buf_unref(buf);
}

ZTEST(net_buf_tests, test_net_buf_user_data_copy)
{
	struct net_buf *buf_user_data_small, *buf_user_data_big;
	uint32_t *src_user_data, *dst_user_data;

	buf_user_data_small = net_buf_alloc_len(&bufs_pool, 1, K_NO_WAIT);
	zassert_not_null(buf_user_data_small, "Failed to get buffer");
	src_user_data = net_buf_user_data(buf_user_data_small);
	*src_user_data = 0xAABBCCDD;

	/* Happy case: Size of user data in destination buf is bigger than the source buf one */
	buf_user_data_big = net_buf_alloc_len(&var_pool, 1, K_NO_WAIT);
	zassert_not_null(buf_user_data_big, "Failed to get buffer");
	dst_user_data = net_buf_user_data(buf_user_data_big);
	*dst_user_data = 0x11223344;

	zassert_ok(net_buf_user_data_copy(buf_user_data_big, buf_user_data_small));
	zassert_equal(*src_user_data, 0xAABBCCDD);

	/* Error case: User data size of destination buffer is too small */
	zassert_not_ok(net_buf_user_data_copy(buf_user_data_small, buf_user_data_big),
		       "User data size in destination buffer too small");

	net_buf_unref(buf_user_data_big);

	/* Corner case: Same buffer used as source and target */
	zassert_ok(net_buf_user_data_copy(buf_user_data_small, buf_user_data_small),
		   "No-op is tolerated");
	zassert_equal(*src_user_data, 0xAABBCCDD, "User data remains the same");

	net_buf_unref(buf_user_data_small);
}

ZTEST(net_buf_tests, test_net_buf_comparison)
{
	struct net_buf *buf;
	size_t written;
	size_t offset;
	size_t to_compare;
	size_t res;
	uint8_t data[FIXED_BUFFER_SIZE * 2];

	/* Fill data buffer */
	for (int i = 0; i < sizeof(data); ++i) {
		data[i] = (uint8_t)i;
	}

	/* Allocate a single net_buf  */
	buf = net_buf_alloc(&fixed_pool, K_NO_WAIT);
	zassert_not_null(buf, "Failed to get buffer");

	written = net_buf_append_bytes(buf, buf->size, data, K_NO_WAIT, NULL, NULL);
	zassert_equal(written, buf->size, "Failed to fill the buffer");
	zassert_equal(buf->frags, NULL, "Additional buffer allocated");

	/* Compare the whole buffer */
	res = net_buf_data_match(buf, 0, data, buf->size);
	zassert_equal(res, buf->size, "Whole net_buf comparison failed");

	/* Compare from the offset */
	offset = buf->size / 2;
	to_compare = written - offset;

	res = net_buf_data_match(buf, offset, &data[offset], to_compare);
	zassert_equal(res, to_compare, "Comparison with offset failed");

	/* Write more data (it allocates more buffers) */
	written = net_buf_append_bytes(buf, sizeof(data) - written, &data[buf->size], K_NO_WAIT,
				       NULL, NULL);
	zassert_true(buf->frags, "Failed to allocate an additional net_buf");

	/* Compare whole data with buffers' content */
	res = net_buf_data_match(buf, 0, data, sizeof(data));
	zassert_equal(res, sizeof(data), "Failed to compare data with multiple buffers");

	/* Compare data with offset at the edge between two fragments */
	offset = buf->size - (buf->size / 2);
	res = net_buf_data_match(buf, offset, &data[offset], buf->size);
	zassert_equal(res, buf->size, "Failed to compare bytes within two buffers with offset");

	/* Compare data with partial matching - change the data in the middle */
	data[sizeof(data) / 2] += 1;
	res = net_buf_data_match(buf, 0, data, sizeof(data));
	zassert_equal(res, sizeof(data) / 2, "Partial matching failed");

	/* No buffer - expect 0 matching bytes */
	res = net_buf_data_match(NULL, 0, data, sizeof(data));
	zassert_equal(res, 0, "Matching without a buffer must fail");

	/* No data - expect 0 matching bytes */
	res = net_buf_data_match(buf, 0, NULL, sizeof(data));
	zassert_equal(res, 0, "Matching without data must fail");

	/* Too high offset - expect 0 matching bytes */
	res = net_buf_data_match(buf, FIXED_BUFFER_SIZE * 2, data, sizeof(data));
	zassert_equal(res, 0, "Matching with too high offset must fail");

	/* Try to match more bytes than are in buffers - expect only partial match */
	offset = (FIXED_BUFFER_SIZE * 2) - 8;
	res = net_buf_data_match(buf, offset, &data[offset], 16);
	zassert_equal(res, 8, "Reaching out of bounds must return a partial match");

	net_buf_unref(buf);
}

ZTEST(net_buf_tests, test_net_buf_fixed_append)
{
	struct net_buf *buf;
	uint8_t data[FIXED_BUFFER_SIZE * 2];

	/* Fill data buffer */
	for (int i = 0; i < sizeof(data); ++i) {
		data[i] = (uint8_t)i;
	}

	/* Fixed Pool */
	buf = net_buf_alloc(&fixed_pool, K_NO_WAIT);
	zassert_not_null(buf, "Failed to get fixed buffer");
	zassert_equal(buf->size, FIXED_BUFFER_SIZE, "Invalid fixed buffer size");

	/* For fixed pool appending less bytes than buffer's free space must
	 * not add a new fragment
	 */
	net_buf_append_bytes(buf, buf->size - 8, data, K_NO_WAIT, NULL, NULL);
	zassert_equal(buf->len, buf->size - 8, "Invalid buffer len");
	zassert_is_null(buf->frags, "Unexpected buffer fragment");

	/* Filling rest of the space should not add an additional buffer */
	net_buf_append_bytes(buf, 8, data, K_NO_WAIT, NULL, NULL);
	zassert_equal(buf->len, buf->size, "Invalid buffer len");
	zassert_is_null(buf->frags, "Unexpected buffer fragment");

	/* Appending any number of bytes allocates an additional fragment */
	net_buf_append_bytes(buf, 1, data, K_NO_WAIT, NULL, NULL);
	zassert_not_null(buf->frags, "Lack of expected buffer fragment");
	zassert_equal(buf->frags->len, 1, "Expected single byte in the new fragment");
	zassert_equal(buf->frags->size, buf->size, "Different size of the fragment");

	/* Remove 1-byte buffer */
	net_buf_frag_del(buf, buf->frags);

	/* Appending size bigger than single buffer's size will allocate multiple fragments */
	net_buf_append_bytes(buf, sizeof(data), data, K_NO_WAIT, NULL, NULL);
	zassert_not_null(buf->frags, "Missing first buffer fragment");
	zassert_not_null(buf->frags->frags, "Missing second buffer fragment");
	zassert_is_null(buf->frags->frags->frags, "Unexpected buffer fragment");

	net_buf_unref(buf);
}


ZTEST_SUITE(net_buf_tests, NULL, NULL, NULL, NULL, NULL);