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misc: improve pcap drop trace output

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Append <nodename>: <error-string> to pcap drop traces.

The data displays perfectly fine in [vanilla] wireshark, and makes it
100% obvious which node dropped the packet, and why.

Type: feature
Ticket: VPP-1776

Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: I9b964b99da4011b93723354db6ef0b128fca20cb
This commit is contained in:
Dave Barach
2019-09-23 16:03:49 -04:00
parent d5ade023bd
commit 9382ad9b39
1 changed files with 54 additions and 0 deletions
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54
src/vnet/interface_output.c
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@ -1177,6 +1177,7 @@ pcap_drop_trace (vlib_main_t * vm,
u32 bi0;
i16 save_current_data;
u16 save_current_length;
vlib_error_main_t *em = &vm->error_main;
from = vlib_frame_vector_args (f);
@ -1222,6 +1223,59 @@ pcap_drop_trace (vlib_main_t * vm,
else if (b0->current_data > 0)
vlib_buffer_advance (b0, (word) - b0->current_data);
{
vlib_buffer_t *last = b0;
u32 error_node_index;
int drop_string_len;
vlib_node_t *n;
/* Length of the error string */
int error_string_len =
clib_strnlen (em->error_strings_heap[b0->error], 128);
/* Dig up the drop node */
error_node_index = vm->node_main.node_by_error[b0->error];
n = vlib_get_node (vm, error_node_index);
/* Length of full drop string, w/ "nodename: " prepended */
drop_string_len = error_string_len + vec_len (n->name) + 2;
/* Find the last buffer in the chain */
while (last->flags & VLIB_BUFFER_NEXT_PRESENT)
last = vlib_get_buffer (vm, last->next_buffer);
/*
* Append <nodename>: <error-string> to the capture,
* only if we can do that without allocating a new buffer.
*/
if (PREDICT_TRUE ((last->current_data + last->current_length)
< (VLIB_BUFFER_DEFAULT_DATA_SIZE
- drop_string_len)))
{
clib_memcpy_fast (last->data + last->current_data +
last->current_length, n->name,
vec_len (n->name));
clib_memcpy_fast (last->data + last->current_data +
last->current_length + vec_len (n->name),
": ", 2);
clib_memcpy_fast (last->data + last->current_data +
last->current_length + vec_len (n->name) +
2, em->error_strings_heap[b0->error],
error_string_len);
last->current_length += drop_string_len;
b0->flags &= ~(VLIB_BUFFER_TOTAL_LENGTH_VALID);
pcap_add_buffer (&pp->pcap_main, vm, bi0,
pp->max_bytes_per_pkt);
last->current_length -= drop_string_len;
b0->current_data = save_current_data;
b0->current_length = save_current_length;
continue;
}
}
/*
* Didn't have space in the last buffer, here's the dropped
* packet as-is
*/
pcap_add_buffer (&pp->pcap_main, vm, bi0, pp->max_bytes_per_pkt);
b0->current_data = save_current_data;