build: add mkrasimage

The current make-ras.sh image generation script for the ZyXEL NBG6617
has portability issues with bash. Because of this, factory images are
currently not built correctly by the OpenWRT buildbots.

This commit replaces the make-ras.sh by C-written mkrasimage.

The new mkrasimage is also compatible with other ZyXEL devices using
the ras image-format.
This is not tested with the NBG6616 but it correctly builds the
header for ZyXEL factory image.

Signed-off-by: David Bauer <mail@david-bauer.net>

2 files changed, 460 insertions, 0 deletions

diff --git a/tools/firmware-utils/Makefile b/tools/firmware-utils/Makefile
index 436a43794c..00917c3417 100644
--- a/tools/firmware-utils/Makefile
+++ b/tools/firmware-utils/Makefile
@@ -70,6 +70,7 @@ define Host/Compile
 	$(call cc,fix-u-media-header cyg_crc32,-Wall)
 	$(call cc,hcsmakeimage bcmalgo)
 	$(call cc,mkporayfw, -Wall)
+	$(call cc,mkrasimage, --std=gnu99)
 	$(call cc,mkhilinkfw, -lcrypto)
 	$(call cc,mkdcs932, -Wall)
 	$(call cc,mkheader_gemtek,-lz)
diff --git a/tools/firmware-utils/src/mkrasimage.c b/tools/firmware-utils/src/mkrasimage.c
new file mode 100644
index 0000000000..8eee29cc08
--- /dev/null
+++ b/tools/firmware-utils/src/mkrasimage.c
@@ -0,0 +1,459 @@
+/*
+ * --- ZyXEL header format ---
+ * Original Version by Benjamin Berg <benjamin@sipsolutions.net>
+ * C implementation based on generation-script by Christian Lamparter <chunkeey@gmail.com>
+ *
+ * The firmware image prefixed with a header (which is written into the MTD device).
+ * The header is one erase block (~64KiB) in size, but the checksum only convers the
+ * first 2KiB. Padding is 0xff. All integers are in big-endian.
+ *
+ * The checksum is always a 16-Bit System V checksum (sum -s) stored in a 32-Bit integer.
+ *
+ *   4 bytes:  checksum of the rootfs image
+ *   4 bytes:  length of the contained rootfs image file (big endian)
+ *  32 bytes:  Firmware Version string (NUL terminated, 0xff padded)
+ *   4 bytes:  checksum over the header partition (big endian - see below)
+ *  64 bytes:  Model (e.g. "NBG6617", NUL termiated, 0xff padded)
+ *   4 bytes:  checksum of the kernel partition
+ *   4 bytes:  length of the contained kernel image file (big endian)
+ *      rest:  0xff padding (To erase block size)
+ *
+ * The kernel partition checksum and length is not used for every device.
+ * If it's notused, pad those 8 bytes with 0xFF.
+ *
+ * The checksums are calculated by adding up all bytes and if a 16bit
+ * overflow occurs, one is added and the sum is masked to 16 bit:
+ *   csum = csum + databyte; if (csum > 0xffff) { csum += 1; csum &= 0xffff };
+ * Should the file have an odd number of bytes then the byte len-0x800 is
+ * used additionally.
+ *
+ * The checksum for the header is calculated over the first 2048 bytes with
+ * the rootfs image checksum as the placeholder during calculation.
+ *
+ * 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 <fcntl.h>
+#include <getopt.h>
+#include <libgen.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <sys/mman.h>
+#include <sys/stat.h>
+
+#include <arpa/inet.h>
+
+#define VERSION_STRING_LEN 31
+#define ROOTFS_HEADER_LEN 40
+
+#define KERNEL_HEADER_LEN 8
+
+#define BOARD_NAME_LEN 64
+#define BOARD_HEADER_LEN 68
+
+#define HEADER_PARTITION_CALC_LENGTH 2048
+#define HEADER_PARTITION_LENGTH 0x10000
+
+struct file_info {
+    char *name;    /* name of the file */
+    char *data;    /* file content */
+    size_t size;   /* length of the file */
+};
+
+static char *progname;
+
+static char *board_name = 0;
+static char *version_name = 0;
+static unsigned int rootfs_size = 0;
+
+static struct file_info kernel = { NULL, NULL, 0 };
+static struct file_info rootfs = { NULL, NULL, 0 };
+static struct file_info rootfs_out = { NULL, NULL, 0 };
+static struct file_info out = { NULL, NULL, 0 };
+
+#define ERR(fmt, ...) do { \
+    fprintf(stderr, "[%s] *** error: " fmt "\n", \
+            progname, ## __VA_ARGS__ ); \
+} while (0)
+
+void map_file(struct file_info *finfo)
+{
+    struct stat file_stat = {0};
+    int fd;
+
+    fd = open(finfo->name, O_RDONLY, (mode_t)0600);
+    if (fd == -1) {
+        ERR("Error while opening file %s.", finfo->name);
+        exit(EXIT_FAILURE);
+    }
+
+    if (fstat(fd, &file_stat) == -1) {
+        ERR("Error getting file size for %s.", finfo->name);
+        exit(EXIT_FAILURE);
+    }
+
+    finfo->size = file_stat.st_size;
+    finfo->data = mmap(0, finfo->size, PROT_READ, MAP_SHARED, fd, 0);
+
+    if (finfo->data == MAP_FAILED) {
+        ERR("Error mapping file %s.", finfo->name);
+        exit(EXIT_FAILURE);
+    }
+
+    close(fd);
+}
+
+void unmap_file(struct file_info *finfo)
+{
+    if(munmap(finfo->data, finfo->size) == -1) {
+        ERR("Error unmapping file %s.", finfo->name);
+        exit(EXIT_FAILURE);
+    }
+}
+
+void write_file(struct file_info *finfo)
+{
+    FILE *fout = fopen(finfo->name, "w");
+
+    fwrite(finfo->data, finfo->size, 1, fout);
+
+    if (ferror(fout)) {
+        ERR("Wanted to write, but something went wrong.");
+        exit(EXIT_FAILURE);
+    }
+
+    fclose(fout);
+}
+
+void usage(int status)
+{
+    FILE *stream = (status != EXIT_SUCCESS) ? stderr : stdout;
+
+    fprintf(stream, "Usage: %s [OPTIONS...]\n", progname);
+    fprintf(stream,
+            "\n"
+            "Options:\n"
+            "  -k <kernel>     path for kernel image\n"
+            "  -r <rootfs>     path for rootfs image\n"
+            "  -s <rfssize>    size of output rootfs\n"
+            "  -v <version>    version string\n"
+            "  -b <boardname>  name of board to generate image for\n"
+            "  -o <out_name>   name of output image\n"
+            "  -h              show this screen\n"
+    );
+
+    exit(status);
+}
+
+static int sysv_chksm(const unsigned char *data, int size)
+{
+    int r;
+    int checksum;
+    unsigned int s = 0; /* The sum of all the input bytes, modulo (UINT_MAX + 1).  */
+
+
+    for (int i = 0; i < size; i++) {
+        s += data[i];
+    }
+
+    r = (s & 0xffff) + ((s & 0xffffffff) >> 16);
+    checksum = (r & 0xffff) + (r >> 16);
+
+    return checksum;
+}
+
+static int zyxel_chksm(const unsigned char *data, int size)
+{
+     return htonl(sysv_chksm(data, size));
+}
+
+char *generate_rootfs_header(struct file_info filesystem, char *version)
+{
+    size_t version_string_length;
+    unsigned int chksm, size;
+    char *rootfs_header;
+    size_t ptr = 0;
+
+    rootfs_header = malloc(ROOTFS_HEADER_LEN);
+    if (!rootfs_header) {
+        ERR("Couldn't allocate memory for rootfs header!");
+        exit(EXIT_FAILURE);
+    }
+
+    /* Prepare padding for firmware-version string here */
+    memset(rootfs_header, 0xff, ROOTFS_HEADER_LEN);
+
+    chksm = zyxel_chksm((const unsigned char *)filesystem.data, filesystem.size);
+    size = htonl(filesystem.size);
+
+    /* 4 bytes:  checksum of the rootfs image */
+    memcpy(rootfs_header + ptr, &chksm, 4);
+    ptr += 4;
+
+    /* 4 bytes:  length of the contained rootfs image file (big endian) */
+    memcpy(rootfs_header + ptr, &size, 4);
+    ptr += 4;
+
+    /* 32 bytes:  Firmware Version string (NUL terminated, 0xff padded) */
+    version_string_length = strlen(version) <= VERSION_STRING_LEN ? strlen(version) : VERSION_STRING_LEN;
+    memcpy(rootfs_header + ptr, version, version_string_length);
+    ptr += version_string_length;
+    /* Add null-terminator */
+    rootfs_header[ptr] = 0x0;
+
+    return rootfs_header;
+}
+
+char *generate_kernel_header(struct file_info kernel)
+{
+    unsigned int chksm, size;
+    char *kernel_header;
+    size_t ptr = 0;
+
+    kernel_header = malloc(KERNEL_HEADER_LEN);
+    if (!kernel_header) {
+        ERR("Couldn't allocate memory for kernel header!");
+        exit(EXIT_FAILURE);
+    }
+
+    chksm = zyxel_chksm((const unsigned char *)kernel.data, kernel.size);
+    size = htonl(kernel.size);
+
+    /* 4 bytes:  checksum of the kernel image */
+    memcpy(kernel_header + ptr, &chksm, 4);
+    ptr += 4;
+
+    /* 4 bytes:  length of the contained kernel image file (big endian) */
+    memcpy(kernel_header + ptr, &size, 4);
+
+    return kernel_header;
+}
+
+unsigned int generate_board_header_checksum(char *kernel_hdr, char *rootfs_hdr, char *boardname)
+{
+    char *board_hdr_tmp;
+    unsigned int sum;
+    size_t ptr = 0;
+
+    /*
+     * The checksum of the board header is calculated over the first 2048 bytes of
+     * the header partition with the rootfs checksum used as a placeholder for then
+     * board checksum we calculate in this step. The checksum gained from this step
+     * is then used for the final board header partition.
+     */
+
+    board_hdr_tmp = malloc(HEADER_PARTITION_CALC_LENGTH);
+    if (!board_hdr_tmp) {
+        ERR("Couldn't allocate memory for temporary board header!");
+        exit(EXIT_FAILURE);
+    }
+    memset(board_hdr_tmp, 0xff, HEADER_PARTITION_CALC_LENGTH);
+
+    /* 40 bytes:  RootFS header */
+    memcpy(board_hdr_tmp, rootfs_hdr, ROOTFS_HEADER_LEN);
+    ptr += ROOTFS_HEADER_LEN;
+
+    /* 4 bytes:  RootFS checksum (BE) as placeholder for board-header checksum */
+    memcpy(board_hdr_tmp + ptr, rootfs_hdr, 4);
+    ptr += 4;
+
+    /* 32 bytes:  Model (e.g. "NBG6617", NUL termiated, 0xff padded) */
+    memcpy(board_hdr_tmp + ptr, boardname, strlen(boardname));
+    ptr += strlen(boardname);
+    /* Add null-terminator */
+    board_hdr_tmp[ptr] = 0x0;
+    ptr = ROOTFS_HEADER_LEN + 4 + BOARD_NAME_LEN;
+
+    /* 8 bytes:  Kernel header */
+    if (kernel_hdr)
+        memcpy(board_hdr_tmp + ptr, kernel_hdr, 8);
+
+    /* Calculate the checksum over the first 2048 bytes */
+    sum = zyxel_chksm((const unsigned char *)board_hdr_tmp, HEADER_PARTITION_CALC_LENGTH);
+    free(board_hdr_tmp);
+    return sum;
+}
+
+char *generate_board_header(char *kernel_hdr, char *rootfs_hdr, char *boardname)
+{
+    unsigned int board_checksum;
+    char *board_hdr;
+
+    board_hdr = malloc(BOARD_HEADER_LEN);
+    if (!board_hdr) {
+        ERR("Couldn't allocate memory for board header!");
+        exit(EXIT_FAILURE);
+    }
+    memset(board_hdr, 0xff, BOARD_HEADER_LEN);
+
+    /* 4 bytes:  checksum over the header partition (big endian) */
+    board_checksum = generate_board_header_checksum(kernel_hdr, rootfs_hdr, boardname);
+    memcpy(board_hdr, &board_checksum, 4);
+
+    /* 32 bytes:  Model (e.g. "NBG6617", NUL termiated, 0xff padded) */
+    memcpy(board_hdr + 4, boardname, strlen(boardname));
+    board_hdr[4 + strlen(boardname)] = 0x0;
+
+    return board_hdr;
+}
+
+int build_image()
+{
+    char *rootfs_header = NULL;
+    char *kernel_header = NULL;
+    char *board_header = NULL;
+
+    size_t ptr;
+
+    /* Load files */
+    if (kernel.name)
+        map_file(&kernel);
+    map_file(&rootfs);
+
+    /*
+     * Allocate memory and copy input rootfs for temporary output rootfs.
+     * This is important as we have to generate the rootfs checksum over the
+     * entire rootfs partition. As we might have to pad the partition to allow
+     * for flashing via ZyXEL's Web-GUI, we prepare the rootfs partition for the
+     * output image here (and also use it for calculating the rootfs checksum).
+     *
+     * The roofs padding has to be done with 0x00.
+     */
+    rootfs_out.data = calloc(rootfs_out.size, sizeof(char));
+    memcpy(rootfs_out.data, rootfs.data, rootfs.size);
+
+    /* Prepare headers */
+    rootfs_header = generate_rootfs_header(rootfs_out, version_name);
+    if (kernel.name)
+        kernel_header = generate_kernel_header(kernel);
+    board_header = generate_board_header(kernel_header, rootfs_header, board_name);
+
+    /* Prepare output file */
+    out.size = HEADER_PARTITION_LENGTH + rootfs_out.size;
+    if (kernel.name)
+        out.size += kernel.size;
+    out.data = malloc(out.size);
+    memset(out.data, 0xFF, out.size);
+
+    /* Build output image */
+    memcpy(out.data, rootfs_header, ROOTFS_HEADER_LEN);
+    memcpy(out.data + ROOTFS_HEADER_LEN, board_header, BOARD_HEADER_LEN);
+    if (kernel.name)
+        memcpy(out.data + ROOTFS_HEADER_LEN + BOARD_HEADER_LEN, kernel_header, KERNEL_HEADER_LEN);
+    ptr = HEADER_PARTITION_LENGTH;
+    memcpy(out.data + ptr, rootfs_out.data, rootfs_out.size);
+    ptr += rootfs_out.size;
+    if (kernel.name)
+        memcpy(out.data + ptr, kernel.data, kernel.size);
+
+    /* Write back output image */
+    write_file(&out);
+
+    /* Free allocated memory */
+    if (kernel.name)
+        unmap_file(&kernel);
+    unmap_file(&rootfs);
+    free(out.data);
+    free(rootfs_out.data);
+
+    free(rootfs_header);
+    if (kernel.name)
+        free(kernel_header);
+    free(board_header);
+
+    return 0;
+}
+
+int check_options()
+{
+    if (!rootfs.name) {
+        ERR("No rootfs filename supplied");
+        return -2;
+    }
+
+    if (!out.name) {
+        ERR("No output filename supplied");
+        return -3;
+    }
+
+    if (!board_name) {
+        ERR("No board-name supplied");
+        return -4;
+    }
+
+    if (!version_name) {
+        ERR("No version supplied");
+        return -5;
+    }
+
+    if (rootfs_size <= 0) {
+        ERR("Invalid rootfs size supplied");
+        return -6;
+    }
+
+    if (strlen(board_name) > 31) {
+        ERR("Board name is to long");
+        return -7;
+    }
+    return 0;
+}
+
+int main(int argc, char *argv[])
+{
+    int ret;
+    progname = basename(argv[0]);
+    while (1) {
+        int c;
+
+        c = getopt(argc, argv, "b:k:o:r:s:v:h");
+        if (c == -1)
+            break;
+
+        switch (c) {
+            case 'b':
+                board_name = optarg;
+                break;
+            case 'h':
+                usage(EXIT_SUCCESS);
+                break;
+            case 'k':
+                kernel.name = optarg;
+                break;
+            case 'o':
+                out.name = optarg;
+                break;
+            case 'r':
+                rootfs.name = optarg;
+                break;
+            case 's':
+                sscanf(optarg, "%u", &rootfs_size);
+                break;
+            case 'v':
+                version_name = optarg;
+                break;
+            default:
+                usage(EXIT_FAILURE);
+                break;
+        }
+    }
+
+    ret = check_options();
+    if (ret)
+        usage(EXIT_FAILURE);
+
+    /* As ZyXEL Web-GUI only accept images with a rootfs equal or larger than the first firmware shipped
+     * for the device, we need to pad rootfs partition to this size. To perform further calculations, we
+     * decide the size of this part here. In case the rootfs we want to integrate in our image is larger,
+     * take it's size, otherwise the supplied size.
+     *
+     * Be careful! We rely on assertion of correct size to be performed beforehand. It is unknown if images
+     * with a to large rootfs are accepted or not.
+     */
+    rootfs_out.size = rootfs_size < rootfs.size ? rootfs.size : rootfs_size;
+    return build_image();
+}