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// SPDX-License-Identifier: GPL-2.0-only
/*
* mkbossimg - wrap a firmware image in a Bintec/Teldat BOSS header
*
* Copyright (C) 2009-2013 Sebastien Decourriere <sebtx452@gmail.com>
* Copyright (C) 2026 Simon Wunderlich <sw@simonwunderlich.de>
* Based on mkbrnimg.c
*
* The BOSS bootmonitor found on Bintec elmeg RS-series routers expects a
* 52-byte big-endian header in front of a gzip-compressed image. The board
* family is identified by a magic string, which the bootmonitor reports as
* "Identification" under "Show System Information".
*
* The input file is expected to carry a 52-byte placeholder header, so that
* the payload behind the real header stays aligned to the flash sector size.
* The placeholder is skipped; length and CRC are computed over the remainder.
*/
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>
#include <zlib.h>
/* Image types */
#define IMG_TYPE_BOSS 0x00 /* Compressed BOSS */
#define IMG_TYPE_UBOSS 0x01 /* Uncompressed BOSS (uBoss) */
#define IMG_TYPE_LOGIC 0x02 /* Logic aka first bootloader */
#define IMG_TYPE_BOOTMON 0x03 /* Bootmonitor aka second bootloader */
#define IMG_TYPE_FIRMWARE 0x04 /* Firmware (unknown) */
#define IMG_VER 0x00000000
/*
* In vendor images the two fields called "unknown" here hold the length and
* CRC of an uncompressed section. For gzip images the bootmonitor accepts the
* values below, which is what the original tool always wrote.
*/
#define UNKNOWN_1 0x00FA0524
#define UNKNOWN_2 0x00000000
#define UNKNOWN_3 0x00000000
/* Version 42, high enough that the vendor web UI accepts the upgrade */
#define FW_VERSION 0x002A0000
#define MAGIC_CHAOSENDDRAGON "BINTEC ChaosEndDragon"
#define MAGIC_CLOSEDEYEVISUAL "TELDAT ClosedEyeVisual"
struct boss_header {
char magic[23];
uint32_t fw_version;
uint8_t image_type;
uint32_t image_version;
uint32_t image_length;
uint32_t unknown1;
uint32_t unknown2;
uint32_t crc32;
uint32_t unknown3;
} __attribute__((packed));
static const struct board {
const char *name;
const char *magic;
} boards[] = {
/*
* Verified on the device itself via the bootmonitor's
* "Show System Information" -> "Identification:" field.
*/
{ "rs123", MAGIC_CLOSEDEYEVISUAL },
{ "rs230", MAGIC_CHAOSENDDRAGON },
{ "rs353", MAGIC_CLOSEDEYEVISUAL },
};
static void usage(const char *mess)
{
size_t i;
fprintf(stderr, "Error: %s\n", mess);
fprintf(stderr, "Usage: mkbossimg <board> <input file> <output file>\n");
fprintf(stderr, "Supported boards:");
for (i = 0; i < sizeof(boards) / sizeof(boards[0]); i++)
fprintf(stderr, " %s", boards[i].name);
fprintf(stderr, "\n");
exit(1);
}
static ssize_t write_all(int fd, const void *buf, size_t len)
{
const char *p = buf;
size_t done = 0;
while (done < len) {
ssize_t n = write(fd, p + done, len - done);
if (n < 0) {
if (errno == EINTR)
continue;
return -1;
}
done += (size_t)n;
}
return (ssize_t)done;
}
int main(int argc, char **argv)
{
const char *board_name, *in_path, *out_path;
const char *magic = NULL;
struct boss_header hdr;
struct stat st;
char *map, *payload;
size_t payload_len;
uint32_t crc;
size_t i;
int fd, outfd;
if (argc != 4)
usage("wrong number of arguments");
board_name = argv[1];
in_path = argv[2];
out_path = argv[3];
for (i = 0; i < sizeof(boards) / sizeof(boards[0]); i++) {
if (strcmp(board_name, boards[i].name) == 0) {
magic = boards[i].magic;
break;
}
}
if (!magic) {
fprintf(stderr, "Invalid board type '%s'\n", board_name);
usage("unknown board");
}
fd = open(in_path, O_RDONLY);
if (fd < 0 || fstat(fd, &st) < 0) {
fprintf(stderr, "Error opening '%s': %s\n", in_path, strerror(errno));
exit(1);
}
if ((size_t)st.st_size <= sizeof(hdr)) {
fprintf(stderr, "Input '%s' is too small (%ju bytes)\n",
in_path, (uintmax_t)st.st_size);
exit(1);
}
map = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_SHARED, fd, 0);
if (map == MAP_FAILED) {
fprintf(stderr, "Error mapping '%s': %s\n", in_path, strerror(errno));
exit(1);
}
close(fd);
/* Skip the placeholder header that pads the payload to a sector */
payload = map + sizeof(hdr);
payload_len = (size_t)st.st_size - sizeof(hdr);
if (!((unsigned char)payload[0] == 0x1F && (unsigned char)payload[1] == 0x8B)) {
fprintf(stderr, "Invalid image type: expected gzip magic, got %02X %02X\n",
(unsigned char)payload[0], (unsigned char)payload[1]);
exit(1);
}
memset(&hdr, 0, sizeof(hdr));
strncpy(hdr.magic, magic, sizeof(hdr.magic) - 1);
hdr.fw_version = htonl(FW_VERSION);
hdr.image_type = IMG_TYPE_BOSS;
hdr.image_version = htonl(IMG_VER);
hdr.unknown1 = htonl(UNKNOWN_1);
hdr.unknown2 = htonl(UNKNOWN_2);
hdr.unknown3 = htonl(UNKNOWN_3);
crc = crc32(0, (const unsigned char *)payload, payload_len);
hdr.image_length = htonl((uint32_t)payload_len);
hdr.crc32 = htonl(crc);
fprintf(stderr, "Board '%s' magic '%s', crc32 %08x, length %08zx\n",
board_name, magic, crc, payload_len);
outfd = open(out_path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
if (outfd < 0) {
fprintf(stderr, "Error opening '%s' for writing: %s\n",
out_path, strerror(errno));
exit(1);
}
if (write_all(outfd, &hdr, sizeof(hdr)) < 0 ||
write_all(outfd, payload, payload_len) < 0) {
fprintf(stderr, "Error writing '%s': %s\n", out_path, strerror(errno));
exit(1);
}
close(outfd);
munmap(map, (size_t)st.st_size);
return EXIT_SUCCESS;
}
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