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ovs-ofctl: Implement compose-packet --bare [--bad-csum].

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With --bare, it will produce a bare hexified payload with no spaces or
offset indicators inserted, which is useful in tests to produce frames
to pass to e.g. `ovs-ofctl receive`.

With --bad-csum, it will produce a frame that has an invalid IP checksum
(applicable to IPv4 only because IPv6 doesn't have checksums.)

The command is now more useful in tests, where we may need to produce
hex frame payloads to compare observed frames against.

As an example of the tool use, a single test case is converted to it.
The test uses both normal --bare and --bad-csum behaviors of the
command, confirming they work as advertised.

Acked-by: Simon Horman <horms@ovn.org>
Signed-off-by: Ihar Hrachyshka <ihrachys@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
This commit is contained in:
Ihar Hrachyshka
2023-11-14 17:59:37 +00:00
committed by Ilya Maximets
parent 3e0d8d1f4b
commit c62b4ac8f8
7 changed files with 81 additions and 40 deletions
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17
lib/flow.c
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@@ -3306,6 +3306,8 @@ packet_expand(struct dp_packet *p, const struct flow *flow, size_t size)
* (This is useful only for testing, obviously, and the packet isn't really
* valid. Lots of fields are just zeroed.)
*
* If 'bad_csum' is true, the final IP checksum is invalid.
*
* For packets whose protocols can encapsulate arbitrary L7 payloads, 'l7' and
* 'l7_len' determine that payload:
*
@@ -3318,7 +3320,7 @@ packet_expand(struct dp_packet *p, const struct flow *flow, size_t size)
* from 'l7'. */
void
flow_compose(struct dp_packet *p, const struct flow *flow,
const void *l7, size_t l7_len)
const void *l7, size_t l7_len, bool bad_csum)
{
/* Add code to this function (or its callees) for emitting new fields or
* protocols. (This isn't essential, so it can be skipped for initial
@@ -3370,7 +3372,18 @@ flow_compose(struct dp_packet *p, const struct flow *flow,
/* Checksum has already been zeroed by put_zeros call. */
ip->ip_csum = csum(ip, sizeof *ip);
dp_packet_ol_set_ip_csum_good(p);
if (bad_csum) {
/*
* Internet checksum is a sum complement to zero, so any other
* value will result in an invalid checksum. Here, we flip one
* bit.
*/
ip->ip_csum ^= (OVS_FORCE ovs_be16) 0x1;
dp_packet_ip_checksum_bad(p);
} else {
dp_packet_ol_set_ip_csum_good(p);
}
pseudo_hdr_csum = packet_csum_pseudoheader(ip);
flow_compose_l4_csum(p, flow, pseudo_hdr_csum);
} else if (flow->dl_type == htons(ETH_TYPE_IPV6)) {