net: Add option for tracing packets

Add an option to trace all packets send/received. This can be helpful when
debugging protocol issues, as the packets can then be imported into
wireshark [1] and analyzed further.

[1] https://www.wireshark.org/docs/wsug_html_chunked/ChIOImportSection.html

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

Author: Forty-Bot

include/net.h

@@ -16,6 +16,7 @@
 #include <asm/cache.h>
 #include <asm/byteorder.h>	/* for nton* / ntoh* stuff */
 #include <env.h>
+#include <hexdump.h>
 #include <log.h>
 #include <time.h>
 #include <linux/if_ether.h>
@@ -29,6 +30,7 @@ struct udevice;
 #define DEBUG_DEV_PKT 0		/* Packets or info directed to the device */
 #define DEBUG_NET_PKT 0		/* Packets on info on the network at large */
 #define DEBUG_INT_STATE 0	/* Internal network state changes */
+#define DEBUG_NET_PKT_TRACE 0	/* Trace all packet data */
 
 /*
  *	The number of receive packet buffers, and the required packet buffer
@@ -640,6 +642,8 @@ uchar * net_get_async_tx_pkt_buf(void);
 /* Transmit a packet */
 static inline void net_send_packet(uchar *pkt, int len)
 {
+	if (DEBUG_NET_PKT_TRACE)
+		print_hex_dump_bytes("tx: ", DUMP_PREFIX_OFFSET, pkt, len);
 	/* Currently no way to return errors from eth_send() */
 	(void) eth_send(pkt, len);
 }

net/net.c

@@ -1201,6 +1201,9 @@ void net_process_received_packet(uchar *in_packet, int len)
 	ushort cti = 0, vlanid = VLAN_NONE, myvlanid, mynvlanid;
 
 	debug_cond(DEBUG_NET_PKT, "packet received\n");
+	if (DEBUG_NET_PKT_TRACE)
+		print_hex_dump_bytes("rx: ", DUMP_PREFIX_OFFSET, in_packet,
+				     len);
 
 #if defined(CONFIG_CMD_PCAP)
 	pcap_post(in_packet, len, false);