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gnrc_pktbuf: add gnrc_pktbuf_reverse_snips() helper function

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This allows for

a) testing the packet reversal properly in unittests
b) use it in other places than `gnrc_ipv6`'s receive function
This commit is contained in:
Martine Lenders 2018-10-22 21:08:36 +02:00
parent 85733a7568
commit ac54a2d2b2
2 changed files with 41 additions and 0 deletions
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18
sys/include/net/gnrc/pktbuf.h
View File

@ -225,6 +225,24 @@ gnrc_pktsnip_t *gnrc_pktbuf_remove_snip(gnrc_pktsnip_t *pkt, gnrc_pktsnip_t *sni
*/
gnrc_pktsnip_t *gnrc_pktbuf_replace_snip(gnrc_pktsnip_t *pkt, gnrc_pktsnip_t *old, gnrc_pktsnip_t *add);
/**
* @brief Reverses snip order of a packet in a write-protected manner.
*
* This can be used to change the send/receive order of a packet (see
* @ref gnrc_pktsnip_t)
*
* @note @p pkt is released on failure.
*
* @param[in] pkt A packet. When this function fails (due to a full packet
* packet buffer) @p pkt will be released.
*
* @return The reversed version of @p pkt on success
* @return NULL, when there is not enough space in the packet buffer to reverse
* the packet in a write-protected manner. @p pkt is released in that
* case.
*/
gnrc_pktsnip_t *gnrc_pktbuf_reverse_snips(gnrc_pktsnip_t *pkt);
/**
* @brief Duplicates pktsnip chain upto (including) a snip with the given type
* as a continuous snip.

23
sys/net/gnrc/pktbuf/gnrc_pktbuf.c
View File

@ -86,5 +86,28 @@ gnrc_pktsnip_t *gnrc_pktbuf_replace_snip(gnrc_pktsnip_t *pkt,
return pkt;
}
gnrc_pktsnip_t *gnrc_pktbuf_reverse_snips(gnrc_pktsnip_t *pkt)
{
gnrc_pktsnip_t *reversed = NULL, *ptr = pkt;
while (ptr != NULL) {
gnrc_pktsnip_t *next;
/* try to write-protect snip as its next-pointer is changed below */
pkt = gnrc_pktbuf_start_write(ptr); /* use pkt as temporary variable */
if (pkt == NULL) {
gnrc_pktbuf_release(reversed);
gnrc_pktbuf_release(ptr);
return NULL;
}
/* switch around pointers */
next = pkt->next;
pkt->next = reversed;
reversed = pkt;
ptr = next;
}
return reversed;
}
/** @} */