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net: pkt: introduce net_pkt_remove_tail()

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Introduce a helper function for being able to remove any arbitrary
length from tail of packet. This is handy in cases when removing
unneeded data, like CRC once it was verified.

Signed-off-by: Marcin Niestroj <m.niestroj@emb.dev>
This commit is contained in:
Marcin Niestroj 2021-07-15 08:52:13 +02:00 • committed by Christopher Friedt
commit 1ce1d19bb5
3 changed files with 132 additions and 1 deletions
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16
include/net/net_pkt.h
View file

@ -1705,6 +1705,22 @@ size_t net_pkt_available_payload_buffer(struct net_pkt *pkt,
*/
void net_pkt_trim_buffer(struct net_pkt *pkt);
/**
* @brief Remove @a length bytes from tail of packet
*
* @details This function does not take packet cursor into account. It is a
* helper to remove unneeded bytes from tail of packet (like appended
* CRC). It takes care of buffer deallocation if removed bytes span
* whole buffer(s).
*
* @param pkt Network packet
* @param length Number of bytes to be removed
*
* @retval 0 On success.
* @retval -EINVAL If packet length is shorter than @a length.
*/
int net_pkt_remove_tail(struct net_pkt *pkt, size_t length);
/**
* @brief Initialize net_pkt cursor
*

30
subsys/net/ip/net_pkt.c
View file

@ -1089,6 +1089,36 @@ void net_pkt_trim_buffer(struct net_pkt *pkt)
}
}
int net_pkt_remove_tail(struct net_pkt *pkt, size_t length)
{
struct net_buf *buf = pkt->buffer;
size_t remaining_len = net_pkt_get_len(pkt);
if (remaining_len < length) {
return -EINVAL;
}
remaining_len -= length;
while (buf) {
if (buf->len >= remaining_len) {
buf->len = remaining_len;
if (buf->frags) {
net_pkt_frag_unref(buf->frags);
buf->frags = NULL;
}
break;
}
remaining_len -= buf->len;
buf = buf->frags;
}
return 0;
}
#if NET_LOG_LEVEL >= LOG_LEVEL_DBG
int net_pkt_alloc_buffer_debug(struct net_pkt *pkt,
size_t size,

87
tests/net/net_pkt/src/main.c
View file

@ -974,6 +974,90 @@ static void test_net_pkt_get_contiguous_len(void)
net_pkt_unref(pkt);
}
void test_net_pkt_remove_tail(void)
{
struct net_pkt *pkt;
int err;
pkt = net_pkt_alloc_with_buffer(NULL,
CONFIG_NET_BUF_DATA_SIZE * 2 + 3,
AF_UNSPEC, 0, K_NO_WAIT);
zassert_true(pkt != NULL, "Pkt not allocated");
net_pkt_cursor_init(pkt);
net_pkt_write(pkt, small_buffer, CONFIG_NET_BUF_DATA_SIZE * 2 + 3);
zassert_equal(net_pkt_get_len(pkt), CONFIG_NET_BUF_DATA_SIZE * 2 + 3,
"Pkt length is invalid");
zassert_equal(pkt->frags->frags->frags->len, 3,
"3rd buffer length is invalid");
/* Remove some bytes from last buffer */
err = net_pkt_remove_tail(pkt, 2);
zassert_equal(err, 0, "Failed to remove tail");
zassert_equal(net_pkt_get_len(pkt), CONFIG_NET_BUF_DATA_SIZE * 2 + 1,
"Pkt length is invalid");
zassert_not_equal(pkt->frags->frags->frags, NULL,
"3rd buffer was removed");
zassert_equal(pkt->frags->frags->frags->len, 1,
"3rd buffer length is invalid");
/* Remove last byte from last buffer */
err = net_pkt_remove_tail(pkt, 1);
zassert_equal(err, 0, "Failed to remove tail");
zassert_equal(net_pkt_get_len(pkt), CONFIG_NET_BUF_DATA_SIZE * 2,
"Pkt length is invalid");
zassert_equal(pkt->frags->frags->frags, NULL,
"3rd buffer was not removed");
zassert_equal(pkt->frags->frags->len, CONFIG_NET_BUF_DATA_SIZE,
"2nd buffer length is invalid");
/* Remove 2nd buffer and one byte from 1st buffer */
err = net_pkt_remove_tail(pkt, CONFIG_NET_BUF_DATA_SIZE + 1);
zassert_equal(err, 0, "Failed to remove tail");
zassert_equal(net_pkt_get_len(pkt), CONFIG_NET_BUF_DATA_SIZE - 1,
"Pkt length is invalid");
zassert_equal(pkt->frags->frags, NULL,
"2nd buffer was not removed");
zassert_equal(pkt->frags->len, CONFIG_NET_BUF_DATA_SIZE - 1,
"1st buffer length is invalid");
net_pkt_unref(pkt);
pkt = net_pkt_rx_alloc_with_buffer(NULL,
CONFIG_NET_BUF_DATA_SIZE * 2 + 3,
AF_UNSPEC, 0, K_NO_WAIT);
net_pkt_cursor_init(pkt);
net_pkt_write(pkt, small_buffer, CONFIG_NET_BUF_DATA_SIZE * 2 + 3);
zassert_equal(net_pkt_get_len(pkt), CONFIG_NET_BUF_DATA_SIZE * 2 + 3,
"Pkt length is invalid");
zassert_equal(pkt->frags->frags->frags->len, 3,
"3rd buffer length is invalid");
/* Remove bytes spanning 3 buffers */
err = net_pkt_remove_tail(pkt, CONFIG_NET_BUF_DATA_SIZE + 5);
zassert_equal(err, 0, "Failed to remove tail");
zassert_equal(net_pkt_get_len(pkt), CONFIG_NET_BUF_DATA_SIZE - 2,
"Pkt length is invalid");
zassert_equal(pkt->frags->frags, NULL,
"2nd buffer was not removed");
zassert_equal(pkt->frags->len, CONFIG_NET_BUF_DATA_SIZE - 2,
"1st buffer length is invalid");
/* Try to remove more bytes than packet has */
err = net_pkt_remove_tail(pkt, CONFIG_NET_BUF_DATA_SIZE);
zassert_equal(err, -EINVAL,
"Removing more bytes than available should fail");
net_pkt_unref(pkt);
}
void test_main(void)
{
eth_if = net_if_get_default();
@ -989,7 +1073,8 @@ void test_main(void)
ztest_unit_test(test_net_pkt_clone),
ztest_unit_test(test_net_pkt_headroom),
ztest_unit_test(test_net_pkt_headroom_copy),
ztest_unit_test(test_net_pkt_get_contiguous_len)
ztest_unit_test(test_net_pkt_get_contiguous_len),
ztest_unit_test(test_net_pkt_remove_tail)
);
ztest_run_test_suite(net_pkt_tests);