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/*
* WRT400n - Firmware Generation Creator
*
* Creates a firmware image for the Linksys WRT400n router,
* that can be uploaded via the firmware upload page,
* from a kernel image file and root fs file
*
* Author: Sandeep Mistry
* Author: Yousong Zhou
* - remove size limit on kernel and rootfs part
*/
#include <arpa/inet.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include "cyg_crc.h"
// Prelimiary test shows that the OEM upgrade program only checks checksum of
// the whole firmware image, ignoring specific checksums of kernel and rootfs
// part. But we are computing crc32 sums of fixed length of data here in lieu
// of read_fw utility found in OEM SDK
#define CRC_SZ_KERNEL 0x100000
#define CRC_SZ_ROOTFS 0x2fffc4
// OEM firmware has size limit on "linux" and "rootfs" partition. That's also
// the limit for factory firmware images as fwupgrade utility in the OEM system
// needs to write kernel and rootfs to those two partitions (/dev/mtd2 and
// /dev/mtd3 to be exact)
#define SZ_MAX_KERNEL (0x180000 - 0x40000)
#define SZ_MAX_ROOTFS (0x7b0000 - 0x18000)
// Header format:
//
// GPL Tarball: http://downloads.linksysbycisco.com/downloads/WRT400N_1.0.01.19_US.tar,0.gz
// File: WRT400N_1.0.01.19_US/FW_WRT400N_1.0.01.19_US_20081229/GTK/user/include/fw_upgrade.h
//
// Description
// - checksum: CRC32 of kernel and root fs, back to back
// - magic: GMTKRT400N
// - kernel_length: kernel length in bytes
// - kernel_upgrade_flag: should we upgrade the kernel - set to 1
// - rootfs_length: root fs length in byte
// - rootfs_upgrade_flag: should we upgrade the root fs - set to 1
// - kernel_checksum: Gary S. Brown's 32 bit CRC algorithm for kernel, with remaining bits
// set to 0xFF upto 0x100000 bytes (total length)
// - rootfs_checksum: Gary S. Brown's 32 bit CRC algorithm for root fs, with remaining bits
// set to 0xFF upto 0x2FFFC4 bytes (total length)
// - fw_totalsize: total firmware image file length (header length + kernel length + root fs length)
// - reserved[4]: reserved ??? - set to all 0xFF
struct imghdr_t
{
uint32_t checksum; /* CRC32 */
uint8_t magic[12]; /* The value of GTIMG_MAGIC */
uint32_t kernel_length; /* The length of the kernel image */
//uint32_t kernel_entry_point; /* Kernel's entry point for RedBoot's information */
uint32_t kernel_upgrade_flag; /* Set to 1 if we need to upgrade the kernel parition of the Flash */
uint32_t rootfs_length; /* The length of the rootfs image */
//uint32_t rootfs_entry_point; /* Not in use */
uint32_t rootfs_upgrade_flag; /* Set to 1 if we need to upgrade the rootfs parition of the Flash */
// Add 3 items by Vic Yu, 2006-05/10
uint32_t kernel_checksum;
uint32_t rootfs_checksum;
uint32_t fw_totalsize;
uint32_t reserved[4];
};
struct file_info {
char *filename;
int filesize;
int fd;
uint32_t crc32sum;
int crc_sz;
};
int get_file_info(struct file_info *fi, uint32_t *crc32_acc)
{
int fd;
int filesize = 0;
uint32_t crc32sum = 0;
uint32_t _crc32_acc;
int crc_rem = fi->crc_sz;
int sz;
char buf[1024];
if (crc32_acc)
_crc32_acc = *crc32_acc;
else
_crc32_acc = 0;
fd = open(fi->filename, O_RDONLY);
if(fd < 0) {
fprintf(stderr, "error: opening '%s'\n", fi->filename);
return -1;
}
while (true) {
sz = read(fd, buf, sizeof(buf));
if (sz > 0) {
if (crc32_acc)
_crc32_acc = cyg_crc32_accumulate(_crc32_acc, buf, sz);
if (crc_rem > 0) {
if (crc_rem < sz) {
crc32sum = cyg_crc32_accumulate(crc32sum, buf, crc_rem);
crc_rem = 0;
} else {
crc32sum = cyg_crc32_accumulate(crc32sum, buf, sz);
crc_rem -= sz;
}
}
filesize += sz;
} else if (sz == 0) {
break;
} else {
fprintf(stderr, "error read '%s'", strerror(errno));
return -1;
}
}
if (crc_rem) {
memset(buf, 0xff, sizeof(buf));
while (crc_rem > 0) {
if (crc_rem > sizeof(buf)) {
crc32sum = cyg_crc32_accumulate(crc32sum, buf, sizeof(buf));
crc_rem -= sizeof(buf);
} else {
crc32sum = cyg_crc32_accumulate(crc32sum, buf, crc_rem);
crc_rem = 0;
break;
}
}
}
fi->fd = fd;
fi->filesize = filesize;
fi->crc32sum = crc32sum;
if (crc32_acc)
*crc32_acc = _crc32_acc;
return 0;
}
int copy_file(int fromfd, int tofd)
{
int szr, szw;
int buf[4096];
if (lseek(fromfd, SEEK_SET, 0) < 0) {
fprintf(stderr, "lseek: %s\n", strerror(errno));
return -1;
}
while (true) {
szr = read(fromfd, buf, sizeof(buf));
if (szr > 0) {
szw = write(tofd, buf, szr);
if (szw != szr) {
fprintf(stderr, "copy_file: error writing %d bytes: %s\n", szr, strerror(errno));
return -1;
}
} else if (szr == 0) {
break;
} else {
fprintf(stderr, "copy_file: error reading: %s\n", strerror(errno));
return -1;
}
}
return 0;
}
int main(int argc, char *argv[])
{
struct file_info kernel_fi;
struct file_info rootfs_fi;
struct file_info output_fi;
struct imghdr_t ih;
int fd, sz;
int ret = -1;
if(argc != 4) {
printf("Usage:\n\t%s <kernel file> <rootfs file> <output file>\n", argv[0]);
return 1;
}
kernel_fi.crc_sz = CRC_SZ_KERNEL;
rootfs_fi.crc_sz = CRC_SZ_ROOTFS;
kernel_fi.fd = -1;
rootfs_fi.fd = -1;
output_fi.fd = -1;
kernel_fi.filename = argv[1];
rootfs_fi.filename = argv[2];
output_fi.filename = argv[3];
kernel_fi.crc32sum = 0;
rootfs_fi.crc32sum = 0;
output_fi.crc32sum = 0xffffffff;
if (get_file_info(&kernel_fi, &output_fi.crc32sum) < 0)
goto done;
if (get_file_info(&rootfs_fi, &output_fi.crc32sum) < 0)
goto done;
output_fi.crc32sum = ~output_fi.crc32sum;
// print out stats
fprintf(stderr, "%s: size %d (0x%x), crc32 = 0x%x\n",
kernel_fi.filename, kernel_fi.filesize, kernel_fi.filesize, kernel_fi.crc32sum);
fprintf(stderr, "%s: size %d (0x%x), crc32 = 0x%x\n",
rootfs_fi.filename, rootfs_fi.filesize, rootfs_fi.filesize, rootfs_fi.crc32sum);
if (kernel_fi.filesize > SZ_MAX_KERNEL) {
fprintf(stderr, "%s: filesize exceeds 0x%x limit\n", SZ_MAX_KERNEL);
goto done;
}
if (rootfs_fi.filesize > SZ_MAX_ROOTFS) {
fprintf(stderr, "%s: filesize exceeds 0x%x limit\n", SZ_MAX_ROOTFS);
goto done;
}
// now for the header ...
memset(&ih, 0xff, sizeof(ih));
strcpy(ih.magic, "GMTKRT400N");
ih.checksum = htonl(output_fi.crc32sum);
ih.kernel_length = htonl(kernel_fi.filesize);
ih.rootfs_length = htonl(rootfs_fi.filesize);
ih.kernel_upgrade_flag = htonl(0x1);
ih.rootfs_upgrade_flag = htonl(0x1);
ih.kernel_checksum = htonl(kernel_fi.crc32sum);
ih.rootfs_checksum = htonl(rootfs_fi.crc32sum);
ih.fw_totalsize = htonl(kernel_fi.filesize + rootfs_fi.filesize + sizeof(ih));
output_fi.fd = open(output_fi.filename, O_WRONLY | O_CREAT | O_TRUNC,
S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
sz = write(output_fi.fd, &ih, sizeof(ih));
if (sz != sizeof(ih)) {
fprintf(stderr, "error writing imghdr to output: %s\n", strerror(errno));
goto done;
}
if (copy_file(kernel_fi.fd, output_fi.fd)) {
fprintf(stderr, "error copying %s to %s\n", kernel_fi.filename, output_fi.filename);
goto done;
}
if (copy_file(rootfs_fi.fd, output_fi.fd)) {
fprintf(stderr, "error copying %s to %s\n", rootfs_fi.filename, output_fi.filename);
goto done;
}
// print some stats out
fprintf(stderr, "crc = 0x%x, total size = %d (0x%x)\n",
output_fi.crc32sum, ntohl(ih.fw_totalsize), ntohl(ih.fw_totalsize));
ret = 0;
done:
#define CLOSE_FI_FD(fi) do { \
if ((fi).fd >= 0) { \
close((fi).fd); \
} \
} while (0)
CLOSE_FI_FD(kernel_fi);
CLOSE_FI_FD(rootfs_fi);
CLOSE_FI_FD(output_fi);
return ret;
}
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