[U-Boot] [PATCH v2] net: introduce packet capture support

[Ramon Fried <rfried.dev@gmail.com>]

Add support for capturing ethernet packets and storing
them in memory in PCAP(2.4) format, later to be analyzed by
any PCAP viewer software (IE. Wireshark)

This feature greatly assist debugging network issues such
as detecting dropped packets, packet corruption etc.

Signed-off-by: Ramon Fried <rfried.dev@gmail.com>
Reviewed-by: Alex Marginean <alexm.osslist@gmail.com>
Tested-by: Alex Marginean <alexm.osslist@gmail.com>
---
v2: Fix type assignmnet to header.ts_sec
 include/net.h | 29 ++++++++++++++++++
 net/Kconfig   | 22 ++++++++++++++
 net/Makefile  |  1 +
 net/net.c     | 11 +++++++
 net/pcap.c    | 83 +++++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 146 insertions(+)
 create mode 100644 net/pcap.c

diff --git a/include/net.h b/include/net.h
index 44b32385c4..d1dc864896 100644
--- a/include/net.h
+++ b/include/net.h
@@ -630,6 +630,31 @@ bool arp_is_waiting(void);		/* Waiting for ARP reply? */
 void net_set_icmp_handler(rxhand_icmp_f *f); /* Set ICMP RX handler */
 void net_set_timeout_handler(ulong, thand_f *);/* Set timeout handler */
 
+/* PCAP extension */
+
+/**
+ * pcap_init() - Initialize PCAP memory buffer
+ *
+ * @return	0 on success, -ERROR on error
+ */
+int pcap_init(void);
+
+/**
+ * pcap_post() - Post a packet to PCAP file
+ *
+ * @packet:	packet to post
+ * @len:	packet length in bytes
+ * @return	0 on success, -ERROR on error
+ */
+int pcap_post(const void *packet, size_t len);
+
+/**
+ * pcap_size() - get size of PCAP file
+ *
+ * @return	size of PCAP file in bytes
+ */
+unsigned int pcap_size(void);
+
 /* Network loop state */
 enum net_loop_state {
 	NETLOOP_CONTINUE,
@@ -658,6 +683,10 @@ static inline void net_send_packet(uchar *pkt, int len)
 {
 	/* Currently no way to return errors from eth_send() */
 	(void) eth_send(pkt, len);
+
+#if defined(CONFIG_NET_PCAP)
+	pcap_post(pkt, len);
+#endif
 }
 
 /*
diff --git a/net/Kconfig b/net/Kconfig
index 68cecf75a2..f1d3719b04 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -8,6 +8,28 @@ menuconfig NET
 
 if NET
 
+config NET_PCAP
+	bool "PCAP network capture"
+	help
+	  Selecting this will capture all Ethernet packets and store
+	  them in a PCAP formated file later to be analyzed by PCAP
+	  reader application (IE. WireShark).
+
+config NET_PCAP_ADDR
+	hex "Address of PCAP file in memory"
+	depends on NET_PCAP
+	help
+	  Sets the address of the PCAP file in physical memory.
+
+config NET_PCAP_SIZE
+	hex "Size of PCAP file"
+	depends on NET_PCAP
+	default 0x100000
+	help
+	  Sets the maximum size of PCAP file in bytes.
+	  When it fills up completely, it will stop capturing
+	  packets silently.
+
 config NET_RANDOM_ETHADDR
 	bool "Random ethaddr if unset"
 	help
diff --git a/net/Makefile b/net/Makefile
index ce36362168..85103fee93 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -18,6 +18,7 @@ endif
 obj-$(CONFIG_NET)      += eth_common.o
 obj-$(CONFIG_CMD_LINK_LOCAL) += link_local.o
 obj-$(CONFIG_NET)      += net.o
+obj-$(CONFIG_NET_PCAP) += pcap.o
 obj-$(CONFIG_CMD_NFS)  += nfs.o
 obj-$(CONFIG_CMD_PING) += ping.o
 obj-$(CONFIG_CMD_RARP) += rarp.o
diff --git a/net/net.c b/net/net.c
index 58b0417cbe..d0bdf8fe20 100644
--- a/net/net.c
+++ b/net/net.c
@@ -387,6 +387,10 @@ void net_init(void)
 
 		/* Only need to setup buffer pointers once. */
 		first_call = 0;
+
+#if defined(CONFIG_NET_PCAP)
+		pcap_init();
+#endif
 	}
 
 	net_init_loop();
@@ -671,6 +675,10 @@ done:
 	net_set_icmp_handler(NULL);
 #endif
 	net_set_state(prev_net_state);
+
+#if defined(CONFIG_NET_PCAP)
+	printf("PCAP len: 0x%x\n", pcap_size());
+#endif
 	return ret;
 }
 
@@ -1083,6 +1091,9 @@ void net_process_received_packet(uchar *in_packet, int len)
 
 	debug_cond(DEBUG_NET_PKT, "packet received\n");
 
+#if defined(CONFIG_NET_PCAP)
+	pcap_post(in_packet, len);
+#endif
 	net_rx_packet = in_packet;
 	net_rx_packet_len = len;
 	et = (struct ethernet_hdr *)in_packet;
diff --git a/net/pcap.c b/net/pcap.c
new file mode 100644
index 0000000000..d33d57698c
--- /dev/null
+++ b/net/pcap.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 Ramon Fried <rfried.dev@gmail.com>
+ */
+
+#include <common.h>
+#include <net.h>
+#include <time.h>
+#include <asm/io.h>
+
+#define LINKTYPE_ETHERNET	1
+
+static void *buf;
+static unsigned int pos;
+
+struct pcap_header {
+	u32 magic;
+	u16 version_major;
+	u16 version_minor;
+	s32 thiszone;
+	u32 sigfigs;
+	u32 snaplen;
+	u32 network;
+};
+
+struct pcap_packet_header {
+	u32 ts_sec;
+	u32 ts_usec;
+	u32 incl_len;
+	u32 orig_len;
+};
+
+static struct pcap_header file_header = {
+	.magic = 0xa1b2c3d4,
+	.version_major = 2,
+	.version_minor = 4,
+	.snaplen = 65535,
+	.network = LINKTYPE_ETHERNET,
+};
+
+int pcap_init(void)
+{
+	buf = map_physmem(CONFIG_NET_PCAP_ADDR, CONFIG_NET_PCAP_SIZE, 0);
+	if (!buf) {
+		printf("Failed mapping PCAP memory\n");
+		return -ENOMEM;
+	}
+
+	printf("PCAP capture initialized: addr: 0x%lx max length: 0x%x\n",
+	       (unsigned long)buf, CONFIG_NET_PCAP_SIZE);
+
+	memcpy(buf, &file_header, sizeof(file_header));
+	pos += sizeof(file_header);
+	return 0;
+}
+
+int pcap_post(const void *packet, size_t len)
+{
+	struct pcap_packet_header header;
+	u64 cur_time = timer_get_us();
+
+	if (!buf)
+		return -ENODEV;
+	if ((pos + len + sizeof(header)) >= CONFIG_NET_PCAP_SIZE)
+		return -ENOMEM;
+
+	header.ts_sec = cur_time / 1000000;
+	header.ts_usec = cur_time % 1000000;
+	header.incl_len = len;
+	header.orig_len = len;
+
+	memcpy(buf + pos, &header, sizeof(header));
+	pos += sizeof(header);
+	memcpy(buf + pos, packet, len);
+	pos += len;
+
+	return 0;
+}
+
+unsigned int pcap_size(void)
+{
+	return pos;
+}
-- 
2.22.0