OpenWrt – Rev 1
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/*
* Copyright (C) 2015 Thomas Hebb <tommyhebb@gmail.com>
* Copyright (C) 2016 Christian Lamparter <chunkeey@googlemail.com>
*
* The format of the header this tool generates was first documented by
* Chris Blake <chrisrblake93 (at) gmail.com> in a shell script of the
* same purpose. I have created this reimplementation at his request. The
* original script can be found at:
* <https://github.com/riptidewave93/meraki-partbuilder>
*
* Support for the old header format, which is used by the Cisco Z1 AP
* has been reverse engineered from the nandloader's nand_load_bk function.
* The original code is part of Cisco's GPL code and can be found at:
* <https://github.com/riptidewave93/meraki-linux>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <libgen.h>
#include <endian.h>
#include <getopt.h>
#include <errno.h>
#include <arpa/inet.h>
#define PADDING_BYTE 0xff
#define HDR_LENGTH 0x00000020
#define HDR_OFF_MAGIC1 0
#define HDR_OFF_LOAD_ADDR 4
#define HDR_OFF_IMAGELEN 8
#define HDR_OFF_ENTRY 12
#define HDR_OFF_CHECKSUM 16
#define HDR_OFF_FILLER0 20
#define HDR_OFF_FILLER1 24
#define HDR_OFF_FILLER2 28
struct board_info {
char *id;
char *description;
uint32_t magic;
uint32_t imagelen;
uint32_t load_addr;
uint32_t entry;
};
/*
* Globals
*/
static char *progname;
static bool strip_padding;
static char *board_id;
static const struct board_info *board;
static const struct board_info boards[] = {
{
.id = "z1",
.description = "Meraki Z1 Access Point",
.magic = 0x4d495053,
.imagelen = 0x007e0000,
.load_addr = 0x80060000,
.entry = 0x80060000
}, {
/* terminating entry */
}
};
/*
* Message macros
*/
#define ERR(fmt, ...) do { \
fflush(0); \
fprintf(stderr, "[%s] *** error: " fmt "\n", \
progname, ## __VA_ARGS__); \
} while (0)
#define ERRS(fmt, ...) do { \
int save = errno; \
fflush(0); \
fprintf(stderr, "[%s] *** error: " fmt "\n", \
progname, ## __VA_ARGS__, strerror(save)); \
} while (0)
static const struct board_info *find_board(const char *id)
{
const struct board_info *ret;
const struct board_info *board;
ret = NULL;
for (board = boards; board->id != NULL; board++) {
if (strcasecmp(id, board->id) == 0) {
ret = board;
break;
}
}
return ret;
}
static void usage(int status)
{
FILE *stream = (status != EXIT_SUCCESS) ? stderr : stdout;
const struct board_info *board;
fprintf(stream, "Usage: %s [OPTIONS...]\n", progname);
fprintf(stream,
"\n"
"Options:\n"
" -B <board> create image for the board specified with <board>\n"
" -i <file> read kernel image from the file <file>\n"
" -o <file> write output to the file <file>\n"
" -s strip padding from the end of the image\n"
" -h show this screen\n"
);
fprintf(stream, "\nBoards:\n");
for (board = boards; board->id != NULL; board++)
fprintf(stream, " %-16s%s\n", board->id, board->description);
exit(status);
}
static void writel(unsigned char *buf, size_t offset, uint32_t value)
{
value = htonl(value);
memcpy(buf + offset, &value, sizeof(uint32_t));
}
static const uint32_t crc32_table[] = {
0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,
0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,
0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940,
0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116,
0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a,
0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818,
0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c,
0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086,
0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4,
0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe,
0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252,
0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60,
0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04,
0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a,
0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e,
0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0,
0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6,
0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d,
};
static inline uint32_t crc32_accumulate_8(const uint32_t crc, const uint8_t ch)
{
return crc32_table[(crc ^ ch) & 0xff] ^ (crc >> 8);
}
static void crc32_csum(uint8_t *buf, const size_t len)
{
uint32_t crc;
size_t i;
crc = ~0;
for (i = 0; i < len; i += 4) {
crc = crc32_accumulate_8(crc, buf[i + 3]);
crc = crc32_accumulate_8(crc, buf[i + 2]);
crc = crc32_accumulate_8(crc, buf[i + 1]);
crc = crc32_accumulate_8(crc, buf[i]);
}
crc = ~crc;
writel(buf, HDR_OFF_CHECKSUM, crc);
}
static int meraki_build_hdr(const struct board_info *board, const size_t klen,
FILE *out, FILE *in)
{
unsigned char *kernel;
unsigned char *buf;
size_t buflen;
size_t kspace;
size_t rc;
buflen = board->imagelen;
kspace = buflen - HDR_LENGTH;
if (klen > kspace) {
ERR("kernel file is too big - max size: 0x%08lX\n", kspace);
return EXIT_FAILURE;
}
/* If requested, resize buffer to remove padding */
if (strip_padding)
buflen = klen + HDR_LENGTH;
/* Allocate and initialize buffer for final image */
buf = malloc(buflen);
if (buf == NULL) {
ERRS("no memory for buffer: %s\n");
return EXIT_FAILURE;
}
memset(buf, PADDING_BYTE, buflen);
/* Load kernel */
kernel = buf + HDR_LENGTH;
fread(kernel, klen, 1, in);
/* Write magic values and filler */
writel(buf, HDR_OFF_MAGIC1, board->magic);
writel(buf, HDR_OFF_FILLER0, 0);
writel(buf, HDR_OFF_FILLER1, 0);
writel(buf, HDR_OFF_FILLER2, 0);
/* Write load and kernel entry point address */
writel(buf, HDR_OFF_LOAD_ADDR, board->load_addr);
writel(buf, HDR_OFF_ENTRY, board->entry);
/* Write header and image length */
writel(buf, HDR_OFF_IMAGELEN, klen);
/* this gets replaced later, after the checksum has been calculated */
writel(buf, HDR_OFF_CHECKSUM, 0);
/* Write checksum */
crc32_csum(buf, klen + HDR_LENGTH);
rc = fwrite(buf, buflen, 1, out);
free(buf);
return rc == 1 ? EXIT_SUCCESS : EXIT_FAILURE;
}
int main(int argc, char *argv[])
{
int ret = EXIT_FAILURE;
char *ofname = NULL, *ifname = NULL;
FILE *out, *in;
size_t klen;
progname = basename(argv[0]);
while (1) {
int c;
c = getopt(argc, argv, "B:i:o:sh");
if (c == -1)
break;
switch (c) {
case 'B':
board_id = optarg;
break;
case 'i':
ifname = optarg;
break;
case 'o':
ofname = optarg;
break;
case 's':
strip_padding = true;
break;
case 'h':
usage(EXIT_SUCCESS);
break;
default:
usage(EXIT_FAILURE);
break;
}
}
if (board_id == NULL) {
ERR("no board specified");
goto err;
}
board = find_board(board_id);
if (board == NULL) {
ERR("unknown board \"%s\"", board_id);
goto err;
}
if (ifname == NULL) {
ERR("no input file specified");
goto err;
}
if (ofname == NULL) {
ERR("no output file specified");
goto err;
}
in = fopen(ifname, "r");
if (in == NULL) {
ERRS("could not open \"%s\" for reading: %s", ifname);
goto err;
}
/* Get kernel length */
fseek(in, 0, SEEK_END);
klen = ftell(in);
rewind(in);
out = fopen(ofname, "w");
if (out == NULL) {
ERRS("could not open \"%s\" for writing: %s", ofname);
goto err_close_in;
}
ret = meraki_build_hdr(board, klen, out, in);
fclose(out);
err_close_in:
fclose(in);
err:
return ret;
}