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pcapng: record received RSS hash in pcap file

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There is an option for recording RSS hash with packets in the
pcapng standard. This implements this for all received packets.

There is a corner case that can not be addressed with current
DPDK API's. If using rte_flow() and some hardware it is possible
to write a flow rule that uses another hash function like XOR.
But there is no API that records this, or provides the algorithm
info on a per-packet basis.

Wireshark recently merged support for displaying the recorded hash
option (for, yet to be released, version 4.1).

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Tested-by: Ben Magistro <koncept1@gmail.com>
This commit is contained in:
Stephen Hemminger 2022-07-26 14:36:19 -07:00 committed by David Marchand
parent e6b42038e8
commit d2e3c4b8a2
1 changed files with 26 additions and 1 deletions
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27
lib/pcapng/rte_pcapng.c
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@ -4,6 +4,7 @@
#include <errno.h>
#include <net/if.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@ -454,9 +455,10 @@ rte_pcapng_copy(uint16_t port_id, uint32_t queue,
struct pcapng_enhance_packet_block *epb;
uint32_t orig_len, data_len, padding, flags;
struct pcapng_option *opt;
const uint16_t optlen = pcapng_optlen(sizeof(flags)) + pcapng_optlen(sizeof(queue));
uint16_t optlen;
struct rte_mbuf *mc;
uint64_t ns;
bool rss_hash;
#ifdef RTE_LIBRTE_ETHDEV_DEBUG
RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, NULL);
@ -489,6 +491,10 @@ rte_pcapng_copy(uint16_t port_id, uint32_t queue,
goto fail;
}
/* record HASH on incoming packets */
rss_hash = (direction == RTE_PCAPNG_DIRECTION_IN &&
(md->ol_flags & RTE_MBUF_F_RX_RSS_HASH));
/* pad the packet to 32 bit boundary */
data_len = rte_pktmbuf_data_len(mc);
padding = RTE_ALIGN(data_len, sizeof(uint32_t)) - data_len;
@ -500,6 +506,11 @@ rte_pcapng_copy(uint16_t port_id, uint32_t queue,
memset(tail, 0, padding);
}
optlen = pcapng_optlen(sizeof(flags));
optlen += pcapng_optlen(sizeof(queue));
if (rss_hash)
optlen += pcapng_optlen(sizeof(uint8_t) + sizeof(uint32_t));
/* reserve trailing options and block length */
opt = (struct pcapng_option *)
rte_pktmbuf_append(mc, optlen + sizeof(uint32_t));
@ -523,6 +534,20 @@ rte_pcapng_copy(uint16_t port_id, uint32_t queue,
opt = pcapng_add_option(opt, PCAPNG_EPB_QUEUE,
&queue, sizeof(queue));
if (rss_hash) {
uint8_t hash_opt[5];
/* The algorithm could be something else if
* using rte_flow_action_rss; but the current API does not
* have a way for ethdev to report this on a per-packet basis.
*/
hash_opt[0] = PCAPNG_HASH_TOEPLITZ;
memcpy(&hash_opt[1], &md->hash.rss, sizeof(uint32_t));
opt = pcapng_add_option(opt, PCAPNG_EPB_HASH,
&hash_opt, sizeof(hash_opt));
}
/* Note: END_OPT necessary here. Wireshark doesn't do it. */
/* Add PCAPNG packet header */