Re: [PATCH] pcap: fix captured frame length
From: Dror Birkman <hidden>
Date: 2016-01-30 13:38:21
Hi Nicolas, Thanks. I tried to test my application with a pcap file I had, but got weird results, so I wrote back the rte_mbufs in pcap format and hex compared it to my input pcap. Only then I noticed that my original pcap had frames that were captured with a length smaller than the frame length. I guess you can call it pure (bad) luck :) Dror On Thu, Jan 28, 2016 at 8:00 PM, Nicolas Pernas Maradei < nicolas.pernas.maradei@emutex.com> wrote:
quoted hunk
Hi Dror, Good catch. What you are saying makes sense and it is also explained in pcap's documentation. Was your setup unusual though? This might sound like a silly question but I don't remember seeing that issue and I should have since your fix is correct. Nico. On 28/01/16 08:09, Dror Birkman wrote: The actual captured length is header.caplen, whereas header.len is the original length on the wire. Signed-off-by: Dror Birkman <redacted> <redacted> --- Without this fix, if the captured length is smaller than the original length on the wire, mbuf will contain incorrect data. drivers/net/pcap/rte_eth_pcap.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)diff --git a/drivers/net/pcap/rte_eth_pcap.c b/drivers/net/pcap/rte_eth_pcap.c index f9230eb..1d121f8 100644 --- a/drivers/net/pcap/rte_eth_pcap.c +++ b/drivers/net/pcap/rte_eth_pcap.c@@ -220,25 +220,25 @@ eth_pcap_rx(void *queue, buf_size = (uint16_t)(rte_pktmbuf_data_room_size(pcap_q->mb_pool) - RTE_PKTMBUF_HEADROOM); - if (header.len <= buf_size) { + if (header.caplen <= buf_size) { /* pcap packet will fit in the mbuf, go ahead and copy */ rte_memcpy(rte_pktmbuf_mtod(mbuf, void *), packet, - header.len); - mbuf->data_len = (uint16_t)header.len; + header.caplen); + mbuf->data_len = (uint16_t)header.caplen; } else { /* Try read jumbo frame into multi mbufs. */ if (unlikely(eth_pcap_rx_jumbo(pcap_q->mb_pool, mbuf, packet, - header.len) == -1)) + header.caplen) == -1)) break; } - mbuf->pkt_len = (uint16_t)header.len; + mbuf->pkt_len = (uint16_t)header.caplen; mbuf->port = pcap_q->in_port; bufs[num_rx] = mbuf; num_rx++; - rx_bytes += header.len; + rx_bytes += header.caplen; } pcap_q->rx_pkts += num_rx; pcap_q->rx_bytes += rx_bytes; - no title specified @page { } table { border-collapse:collapse;border-spacing:0; empty-cells:show } td, th { vertical-align:top; font-size:12pt;} h1, h2, h3, h4, h5, h6 { clear:both } ol, ul { margin:0; padding:0;} li { list-style: none; margin:0; padding:0;} <!-- "li span.odfLiEnd" - IE 7 issue--> li span. { clear: both; line-height:0; width:0; height:0; margin:0; padding:0; } span.footnodeNumber { padding-right:1em; } span.annotation_style_by_filter { font-size:95%; font-family:Arial; background-color:#fff000; margin:0; border:0; padding:0; } * { margin:0;} .P1_borderStart { font-size:12pt; line-height:120%; margin-top:0cm; font-family:Liberation Serif; writing-mode:page; margin-left:0.3cm; margin-right:0cm; text-indent:0cm; background-color:transparent; padding-bottom:0.247cm; border-bottom-style:none; } .P1 { font-size:12pt; line-height:120%; font-family:Liberation Serif; writing-mode:page; margin-left:0.3cm; margin-right:0cm; text-indent:0cm; background-color:transparent; padding-bottom:0.247cm; padding-top:0cm; border-top-style:none; border-bottom-style:none; } .P1_borderEnd { font-size:12pt; line-height:120%; margin-bottom:0.247cm; font-family:Liberation Serif; writing-mode:page; margin-left:0.3cm; margin-right:0cm; text-indent:0cm; background-color:transparent; padding-top:0cm; border-top-style:none;} .P2_borderStart { font-size:12pt; line-height:120%; margin-top:0cm; font-family:Liberation Serif; writing-mode:page; margin-left:0.3cm; margin-right:0cm; text-indent:0cm; background-color:transparent; padding-bottom:0.247cm; border-bottom-style:none; } .P2 { font-size:12pt; line-height:120%; font-family:Liberation Serif; writing-mode:page; margin-left:0.3cm; margin-right:0cm; text-indent:0cm; background-color:transparent; padding-bottom:0.247cm; padding-top:0cm; border-top-style:none; border-bottom-style:none; } .P2_borderEnd { font-size:12pt; line-height:120%; margin-bottom:0.247cm; font-family:Liberation Serif; writing-mode:page; margin-left:0.3cm; margin-right:0cm; text-indent:0cm; background-color:transparent; padding-top:0cm; border-top-style:none;} .P3_borderStart { font-size:10pt; line-height:120%; margin-top:0cm; font-family:Courier New; writing-mode:page; margin-left:0.3cm; margin-right:0cm; text-indent:0cm; background-color:transparent; padding-bottom:0.247cm; border-bottom-style:none; } .P3 { font-size:10pt; line-height:120%; font-family:Courier New; writing-mode:page; margin-left:0.3cm; margin-right:0cm; text-indent:0cm; background-color:transparent; padding-bottom:0.247cm; padding-top:0cm; border-top-style:none; border-bottom-style:none; } .P3_borderEnd { font-size:10pt; line-height:120%; margin-bottom:0.247cm; font-family:Courier New; writing-mode:page; margin-left:0.3cm; margin-right:0cm; text-indent:0cm; background-color:transparent; padding-top:0cm; border-top-style:none;} .Standard { font-size:12pt; font-family:Liberation Serif; writing-mode:page; } .Internet_20_link { color:#000080; text-decoration:underline; } .T10 { color:#0070c0; } .T11 { color:#0070c0; font-size:12pt; } .T12 { color:#0070c0; font-size:20pt; font-weight:bold; } .T16 { color:#000000; font-size:10pt; } .T2 { color:#0000ff; font-family:Liberation Sans; } .T20 { color:#ff0000; font-size:10pt; font-weight:bold; } .T22 { font-size:10pt; } .T3 { color:#0000ff; font-family:Liberation Sans; font-size:8pt; } .T6 { color:#0000ff; font-size:10pt; } .T7 { color:#000066; font-family:Liberation Sans; font-weight:bold; } .T8 { font-family:Liberation Sans; } <!-- ODF styles with no properties representable as CSS --> {