[EXT] Re: [RFC PATCH] graph: add support for pcap trace for graph

[Stephen Hemminger]

On Fri, 6 Jan 2023 10:40:30 +0000
Amit Prakash Shukla <amitprakashs at marvell.com> wrote:

> Thanks Stephen for the review. Sure, will use lib/pcapng.
> 
> I see dpdk libpcapng adds most of the debugging data, however I would like to add a node name to the packets which I am thinking of adding using 'comment' option under 'Enhanced Packet Block' .
> 
> Please let me know if that's fine.
> 
> Thanks,
> Amit Shukla
> 
> > -----Original Message-----
> > From: Stephen Hemminger <stephen at networkplumber.org>
> > Sent: Friday, December 23, 2022 10:17 PM
> > To: Amit Prakash Shukla <amitprakashs at marvell.com>
> > Cc: Jerin Jacob Kollanukkaran <jerinj at marvell.com>; Kiran Kumar
> > Kokkilagadda <kirankumark at marvell.com>; Nithin Kumar Dabilpuram
> > <ndabilpuram at marvell.com>; dev at dpdk.org
> > Subject: [EXT] Re: [RFC PATCH] graph: add support for pcap trace for graph
> > 
> > External Email
> > 
> > ----------------------------------------------------------------------
> > On Fri, 23 Dec 2022 17:32:35 +0530
> > Amit Prakash Shukla <amitprakashs at marvell.com> wrote:
> >   
> > > +
> > > +	pcap_trace.file_descriptor = open(pcap_trace.file_name,
> > > +					  O_CREAT | O_TRUNC | O_WRONLY,  
> > 0664);  
> > > +	if (pcap_trace.file_descriptor < 0) {
> > > +		ret = 1;
> > > +		goto done;
> > > +	}
> > > +	pcap_trace.n_pcap_data_written = 0;
> > > +
> > > +	/* Write file header. */
> > > +	memset(&file_hdr, 0, sizeof(file_hdr));
> > > +	file_hdr.magic = 0xa1b2c3d4;
> > > +	file_hdr.major_version = 2;
> > > +	file_hdr.minor_version = 4;
> > > +	file_hdr.time_zone = 0;
> > > +	file_hdr.max_packet_size_in_bytes = ((1 << 16) - 1);
> > > +	file_hdr.packet_type = pcap_trace.packet_type;
> > > +	n = write(pcap_trace.file_descriptor, &file_hdr, sizeof(file_hdr));
> > > +	if (n != sizeof(file_hdr)) {
> > > +		ret = 1;
> > > +		goto done;
> > > +	}
> > > +
> > > +	while (pcap_trace.n_bytes > pcap_trace.n_pcap_data_written) {
> > > +		int n = pcap_trace.n_bytes -  
> > pcap_trace.n_pcap_data_written;  
> > > +
> > > +		n = write(pcap_trace.file_descriptor,  
> > 
> > NAK please use lib/pcapng rather than rolling your own pcap format code  

Something like this:

diff --git a/lib/pcapng/rte_pcapng.c b/lib/pcapng/rte_pcapng.c
index cb590ea0096c..216ad80f7ed6 100644
--- a/lib/pcapng/rte_pcapng.c
+++ b/lib/pcapng/rte_pcapng.c
@@ -492,7 +492,8 @@ rte_pcapng_copy(uint16_t port_id, uint32_t queue,
 		const struct rte_mbuf *md,
 		struct rte_mempool *mp,
 		uint32_t length, uint64_t cycles,
-		enum rte_pcapng_direction direction)
+		enum rte_pcapng_direction direction,
+		const char *comment)
 {
 	struct pcapng_enhance_packet_block *epb;
 	uint32_t orig_len, data_len, padding, flags;
@@ -552,6 +553,8 @@ rte_pcapng_copy(uint16_t port_id, uint32_t queue,
 	optlen += pcapng_optlen(sizeof(queue));
 	if (rss_hash)
 		optlen += pcapng_optlen(sizeof(uint8_t) + sizeof(uint32_t));
+	if (comment)
+		optlen += pcapng_optlen(strlen(comment));

 	/* reserve trailing options and block length */
 	opt = (struct pcapng_option *)
@@ -590,6 +593,10 @@ rte_pcapng_copy(uint16_t port_id, uint32_t queue,
 					&hash_opt, sizeof(hash_opt));
 	}

+	if (comment)
+		opt = pcapng_add_option(opt, PCAPNG_OPT_COMMENT,
+					comment, strlen(comment));
+
 	/* Note: END_OPT necessary here. Wireshark doesn't do it. */

 	/* Add PCAPNG packet header */
diff --git a/lib/pcapng/rte_pcapng.h b/lib/pcapng/rte_pcapng.h
index 6b8aaffc6e0f..98f35e8ea177 100644
--- a/lib/pcapng/rte_pcapng.h
+++ b/lib/pcapng/rte_pcapng.h
@@ -126,6 +126,8 @@ enum rte_pcapng_direction {
  *   The timestamp in TSC cycles.
  * @param direction
  *   The direction of the packer: receive, transmit or unknown.
+ * @param comment
+ *  Optional: comment on packet
  *
  * @return
  *   - The pointer to the new mbuf formatted for pcapng_write
@@ -137,7 +139,8 @@ struct rte_mbuf *
 rte_pcapng_copy(uint16_t port_id, uint32_t queue,
 		const struct rte_mbuf *m, struct rte_mempool *mp,
 		uint32_t length, uint64_t timestamp,
-		enum rte_pcapng_direction direction);
+		enum rte_pcapng_direction direction,
+		const char *comment);


 /**