--- /dev/null
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <libgen.h>
+#include <stdarg.h>
+#include <getopt.h>
+#include <string.h>
+#include <errno.h>
+
+#include <netinet/in.h> // htonl
+
+// Usage: mkdapimg [-p] [-m <model>] -s <sig> -i <input> -o <output>
+//
+// e.g.: mkdapimg -s RT3052-AP-DAP1350-3 -i sysupgarde.bin -o factory.bin
+//
+// If the model string <model> is not given, we will assume that
+// the leading characters upto the first "-" is the model.
+//
+// The "-p" (patch) option is used to patch the exisiting image with the
+// specified model and signature.
+// The "-x" (fix) option will recalculate the payload size and checksum
+// during the patch mode operation.
+
+// The img_hdr_struct was taken from the D-Link SDK:
+// DAP-1350_A1_FW1.11NA_GPL/GPL_Source_Code/Uboot/DAP-1350/httpd/header.h
+
+#define MAX_MODEL_NAME_LEN 20
+#define MAX_SIG_LEN 30
+
+struct img_hdr_struct {
+ uint32_t checksum;
+ char model[MAX_MODEL_NAME_LEN];
+ char sig[MAX_SIG_LEN];
+ uint8_t partition;
+ uint8_t hdr_len;
+ uint8_t rsv1;
+ uint8_t rsv2;
+ uint32_t flash_byte_cnt;
+} imghdr ;
+
+char *progname;
+
+void
+perrexit(int code, char *msg)
+{
+ fprintf(stderr, "%s: %s: %s\n", progname, msg, strerror(errno));
+ exit(code);
+}
+
+void
+usage()
+{
+ fprintf(stderr, "usage: %s [-p] [-m model] -s signature -i input -o output\n", progname);
+ exit(1);
+}
+
+int
+main(int ac, char *av[])
+{
+ char model[MAX_MODEL_NAME_LEN+1];
+ char signature[MAX_SIG_LEN+1];
+ int patchmode = 0;
+ int fixmode = 0;
+
+ FILE *ifile, *ofile;
+ int c;
+ uint32_t cksum;
+ uint32_t bcnt;
+
+ progname = basename(av[0]);
+ memset(model, 0, sizeof(model));
+ memset(signature, 0, sizeof(signature));
+
+ while ( 1 ) {
+ int c;
+
+ c = getopt(ac, av, "pxm:s:i:o:");
+ if (c == -1)
+ break;
+
+ switch (c) {
+ case 'p':
+ patchmode = 1;
+ break;
+ case 'x':
+ fixmode = 1;
+ break;
+ case 'm':
+ if (strlen(optarg) > MAX_MODEL_NAME_LEN) {
+ fprintf(stderr, "%s: model name exceeds %d chars\n",
+ progname, MAX_MODEL_NAME_LEN);
+ exit(1);
+ }
+ strcpy(model, optarg);
+ break;
+ case 's':
+ if (strlen(optarg) > MAX_SIG_LEN) {
+ fprintf(stderr, "%s: signature exceeds %d chars\n",
+ progname, MAX_SIG_LEN);
+ exit(1);
+ }
+ strcpy(signature, optarg);
+ break;
+ case 'i':
+ if ((ifile = fopen(optarg, "r")) == NULL)
+ perrexit(1, optarg);
+ break;
+ case 'o':
+ if ((ofile = fopen(optarg, "w")) == NULL)
+ perrexit(1, optarg);
+ break;
+ default:
+ usage();
+ }
+ }
+
+ if (signature[0] == 0 || ifile == NULL || ofile == NULL) {
+ usage();
+ }
+
+ if (model[0] == 0) {
+ char *p = strchr(signature, '-');
+ if (p == NULL) {
+ fprintf(stderr, "%s: model name unknown\n", progname);
+ exit(1);
+ }
+ if (p - signature > MAX_MODEL_NAME_LEN) {
+ *p = 0;
+ fprintf(stderr, "%s: auto model name failed, string %s too long\n", progname, signature);
+ exit(1);
+ }
+ strncpy(model, signature, p - signature);
+ }
+
+ if (patchmode) {
+ if (fread(&imghdr, sizeof(imghdr), 1, ifile) < 0)
+ perrexit(2, "fread on input");
+ }
+
+ for (bcnt = 0, cksum = 0 ; (c = fgetc(ifile)) != EOF ; bcnt++)
+ cksum += c & 0xff;
+
+ if (fseek(ifile, patchmode ? sizeof(imghdr) : 0, SEEK_SET) < 0)
+ perrexit(2, "fseek on input");
+
+ if (patchmode == 0) {
+ // Fill in the header
+ memset(&imghdr, 0, sizeof(imghdr));
+ imghdr.checksum = htonl(cksum);
+ imghdr.partition = 0 ; // don't care?
+ imghdr.hdr_len = sizeof(imghdr);
+ imghdr.flash_byte_cnt = htonl(bcnt);
+ } else {
+ if (ntohl(imghdr.checksum) != cksum) {
+ fprintf(stderr, "%s: patch mode, checksum mismatch\n",
+ progname);
+ if (fixmode) {
+ fprintf(stderr, "%s: fixing\n", progname);
+ imghdr.checksum = htonl(cksum);
+ } else
+ exit(3);
+ } else if (ntohl(imghdr.flash_byte_cnt) != bcnt) {
+ fprintf(stderr, "%s: patch mode, size mismatch\n",
+ progname);
+ if (fixmode) {
+ fprintf(stderr, "%s: fixing\n", progname);
+ imghdr.flash_byte_cnt = htonl(bcnt);
+ } else
+ exit(3);
+ }
+ }
+
+ strncpy(imghdr.model, model, MAX_MODEL_NAME_LEN);
+ strncpy(imghdr.sig, signature, MAX_SIG_LEN);
+
+ if (fwrite(&imghdr, sizeof(imghdr), 1, ofile) < 0)
+ perrexit(2, "fwrite header on output");
+
+ while ((c = fgetc(ifile)) != EOF) {
+ if (fputc(c, ofile) == EOF)
+ perrexit(2, "fputc on output");
+ }
+
+ if (ferror(ifile))
+ perrexit(2, "fgetc on input");
+
+
+ fclose(ofile);
+ fclose(ifile);
+}