[U-Boot] [PATCH v4 1/3] net: introduce packet capture support

[Joe Hershberger]

On Thu, Jul 18, 2019 at 1:44 PM Ramon Fried <rfried.dev at gmail.com> wrote:
>
> 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 at gmail.com>
> Reviewed-by: Alex Marginean <alexm.osslist at gmail.com>
> Tested-by: Alex Marginean <alexm.osslist at gmail.com>
>
> ---
>
> Changes in v4:
> * Move implementation to pcap.c/pcap.h
> * Display error message when memory is exhausted.
> * Populate $pcapsize environment variable with actual capture
>   size.
> * move outgoing pcap_post to eth_send()
>
> Changes in v3:
> * Change to implementation to command based.
> * Added counters for incoming/outgoing packets.
> * Support clearing the capture for multiple captures.
> * Added documentation (separate patch).
>
> Changes in v2:
> Fix type assignmnet to header.ts_sec

[ ... ]

> diff --git a/net/pcap.c b/net/pcap.c
> new file mode 100644
> index 0000000000..4036d8a3fa
> --- /dev/null
> +++ b/net/pcap.c
> @@ -0,0 +1,156 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright 2019 Ramon Fried <rfried.dev at gmail.com>
> + */
> +
> +#include <common.h>
> +#include <net.h>
> +#include <net/pcap.h>
> +#include <time.h>
> +#include <asm/io.h>
> +
> +#define LINKTYPE_ETHERNET      1
> +
> +static bool initialized;
> +static bool running;
> +static bool buffer_full;
> +static void *buf;
> +static unsigned int max_size;
> +static unsigned int pos;
> +
> +static unsigned long incoming_count;
> +static unsigned long outgoing_count;
> +
> +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(phys_addr_t paddr, unsigned long size)
> +{
> +       buf = map_physmem(paddr, size, 0);

Since this is mapping to physmem, and apparently from your
documentation, you need to use the physical memory when writing to a
file or tftp send, how is the mapping typically handled? Maybe we
should be writing to a variable like "pcapaddr" so it can be used in
the write as part of a script.

> +       if (!buf) {
> +               printf("Failed mapping PCAP memory\n");
> +               return -ENOMEM;
> +       }
> +
> +       printf("PCAP capture initialized: addr: 0x%lx max length: %lu\n",
> +              (unsigned long)buf, size);
> +
> +       memcpy(buf, &file_header, sizeof(file_header));
> +       pos = sizeof(file_header);
> +       max_size = size;
> +       initialized = true;
> +       running = false;
> +       buffer_full = false;
> +       incoming_count = 0;
> +       outgoing_count = 0;
> +       return 0;
> +}
> +
> +int pcap_start_stop(bool start)
> +{
> +       if (!initialized) {
> +               printf("error: pcap was not initialized\n");
> +               return -ENODEV;
> +       }
> +
> +       running = start;
> +
> +       return 0;
> +}
> +
> +int pcap_clear(void)
> +{
> +       if (!initialized) {
> +               printf("error: pcap was not initialized\n");
> +               return -ENODEV;
> +       }
> +
> +       pos = sizeof(file_header);
> +       incoming_count = 0;
> +       outgoing_count = 0;
> +       buffer_full = false;
> +
> +       printf("pcap capture cleared\n");
> +       return 0;
> +}
> +
> +int pcap_post(const void *packet, size_t len, bool outgoing)
> +{
> +       struct pcap_packet_header header;
> +       u64 cur_time = timer_get_us();
> +
> +       if (!initialized || !running || !buf)
> +               return -ENODEV;
> +
> +       if (buffer_full)
> +               return -ENOMEM;
> +
> +       if ((pos + len + sizeof(header)) >= max_size) {
> +               buffer_full = true;
> +               printf("\n!!! Buffer is full, consider increasing buffer size !!!\n");
> +               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;
> +
> +       if (outgoing)
> +               outgoing_count++;
> +       else
> +               incoming_count++;
> +
> +       env_set_hex("pcapsize", pos);
> +
> +       return 0;
> +}
> +
> +int pcap_print_status(void)
> +{
> +       if (!initialized) {
> +               printf("pcap was not initialized\n");
> +               return -ENODEV;
> +       }
> +       printf("PCAP status:\n");
> +       printf("\tInitialized addr: 0x%lx\tmax length: %u\n",
> +              (unsigned long)buf, max_size);
> +       printf("\tStatus: %s.\t file size: %u\n", running ? "Active" : "Idle",
> +              pos);
> +       printf("\tIncoming packets: %lu Outgoing packets: %lu\n",
> +              incoming_count, outgoing_count);
> +
> +       return 0;
> +}
> +
> +bool pcap_active(void)
> +{
> +       return running;
> +}
> --
> 2.22.0
>
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