src/zytrx.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * zytrx - add header to images for ZyXEL NR7101
   4  *
   5  * Based on add_header.c - partially based on OpenWrt's
   6  * motorola-bin.c
   7  *
   8  * Copyright (C) 2008 Imre Kaloz  <kaloz@openwrt.org>
   9  *                    Gabor Juhos <juhosg@openwrt.org>
  10  * Copyright (C) 2021 Bjørn Mork <bjorn@mork.no>
  11  */
  12
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <stddef.h>
  16 #include <unistd.h>
  17 #include <errno.h>
  18 #include <fcntl.h>
  19 #include <sys/mman.h>
  20 #include <sys/stat.h>
  21 #include <string.h>
  22 #include <netinet/in.h>
  23 #include <inttypes.h>
  24
  25 #define BPB 8 /* bits/byte */
  26
  27 static uint32_t crc32[1<<BPB];
  28
  29 static void init_crc32(void)
  30 {
  31         const uint32_t poly = ntohl(0x2083b8ed);
  32         int n;
  33
  34         for (n = 0; n < 1<<BPB; n++) {
  35                 uint32_t crc = n;
  36                 int bit;
  37
  38                 for (bit = 0; bit < BPB; bit++)
  39                         crc = (crc & 1) ? (poly ^ (crc >> 1)) : (crc >> 1);
  40                 crc32[n] = crc;
  41         }
  42 }
  43
  44 static uint32_t crc32buf(const unsigned char *buf, size_t len)
  45 {
  46         uint32_t crc = 0xFFFFFFFF;
  47
  48         for (; len; len--, buf++)
  49                 crc = crc32[(uint8_t)crc ^ *buf] ^ (crc >> BPB);
  50         return ~crc;
  51 }
  52
  53 /* HDR0 reversed, to be stored as BE */
  54 #define MAGIC           0x30524448  /* HDR0 reversed, to be stored as BE */
  55
  56 /* All numbers are stored as BE */
  57 struct zytrx_t {
  58         uint32_t magic;
  59         uint32_t len_h;         /* Length of this header */
  60         uint32_t len_t;         /* Total length of file  */
  61         uint32_t crc32_p;       /* Bit inverted 32-bit CRC of image payload */
  62         uint8_t  verInt[32];    /* String "5.0.0.0\n" zero padded */
  63         uint8_t  verExt[32];    /* String "\n" zero padded */
  64         uint32_t len_p;         /* Length of image payload */
  65         uint8_t  pad1[12];      /* zero padding(?) */
  66         uint8_t  code[164];     /* string "3 6035 122 0\n" zero padded */
  67         uint8_t  chipid[8];     /* string "MT7621A" zero padded */
  68         uint8_t  boardid[16];   /* string "NR7101" zero padded */
  69         uint32_t modelid;       /* modelid as 4 BCD digits: 0x07010001 */
  70         uint8_t  pad2[8];       /* zero padding(?) */
  71         uint8_t  swVersionInt[32];      /* ZyXEL version string: "1.00(ABUV.0)D0" zero padded */
  72         uint8_t  swVersionExt[32];      /* identical to swVersionInt  */
  73         uint8_t  pad4[4];       /* zero padding(?) */
  74         uint32_t kernelChksum;  /* no idea how this is computed - reported but not validated */
  75         uint8_t  pad5[4];       /* zero padding(?) */
  76         uint32_t crc32_h;       /* Bit inverted 32-bit CRC of this header payload */
  77         uint8_t  pad6[4];       /* zero padding(?) */
  78 };
  79
  80 /* static?() field values of unknown meaning - maybe ove to board
  81  * table when we know the significance
  82  */
  83 #define VER_INT         "5.0.0.0\n"
  84 #define VER_EXT         "\n"
  85 #define CODE            "3 6035 122 0\n"
  86 #define KERNELCHKSUM    0x12345678
  87
  88 /* table of supported devices using this header format */
  89 static struct board_t {
  90         uint8_t  chipid[8];
  91         uint8_t  boardid[16];
  92         uint32_t modelid;
  93 } boards[] = {
  94         { "MT7621A", "NR7101", 0x07010001 },
  95         {}
  96 };
  97
  98 static int find_board(struct zytrx_t *h, char *board)
  99 {
 100         struct board_t *p;
 101
 102         for (p = boards; p->modelid; p++) {
 103                 if (strncmp((const char *)p->boardid, board, sizeof(p->boardid)))
 104                         continue;
 105                 memcpy(h->chipid, p->chipid, sizeof(h->chipid));
 106                 memcpy(h->boardid, p->boardid, sizeof(h->boardid));
 107                 h->modelid = htonl(p->modelid);
 108                 return 0;
 109         }
 110         return -1;
 111 }
 112
 113 static void usage(const char *name)
 114 {
 115         struct board_t *p;
 116
 117         fprintf(stderr, "Usage:\n");
 118         fprintf(stderr, " %s -B <board> -v <versionstr> -i <file> [-o <outputfile>]\n\n", name);
 119         fprintf(stderr, "Supported <board> values:\n");
 120         for (p = boards; p->modelid; p++)
 121                 fprintf(stderr, "\t%-12s\n", p->boardid);
 122         fprintf(stderr, "\nExample:\n");
 123         fprintf(stderr, " %s -B %s -v foobar-1.0 -i my.img -o out.img\n\n", name,
 124                 boards[0].boardid);
 125         exit(EXIT_FAILURE);
 126 }
 127
 128 static void errexit(const char *msg)
 129 {
 130         fprintf(stderr, "ERR: %s: %s\n", msg, errno ? strerror(errno) : "unknown");
 131         exit(EXIT_FAILURE);
 132 }
 133
 134 static void *map_input(const char *name, size_t *len)
 135 {
 136         struct stat stat;
 137         void *mapped;
 138         int fd;
 139
 140         fd = open(name, O_RDONLY);
 141         if (fd < 0)
 142                 return NULL;
 143         if (fstat(fd, &stat) < 0) {
 144                 close(fd);
 145                 return NULL;
 146         }
 147         *len = stat.st_size;
 148         mapped = mmap(NULL, stat.st_size, PROT_READ, MAP_SHARED, fd, 0);
 149         if (close(fd) < 0) {
 150                 (void) munmap(mapped, stat.st_size);
 151                 return NULL;
 152         }
 153         return mapped;
 154 }
 155
 156 int main(int argc, char **argv)
 157 {
 158         int c, fdout = STDOUT_FILENO;
 159         void *input_file = NULL;
 160         size_t file_len, len;
 161         uint32_t crc;
 162         struct zytrx_t h = {
 163                 .magic          = htonl(MAGIC),
 164                 .len_h          = htonl(sizeof(h)),
 165                 .verInt         = VER_INT,
 166                 .verExt         = VER_EXT,
 167                 .code           = CODE,
 168                 .kernelChksum   = htonl(KERNELCHKSUM),
 169         };
 170
 171         while ((c = getopt(argc, argv, "B:v:i:o:")) != -1) {
 172                 switch (c) {
 173                 case 'B':
 174                         if (find_board(&h, optarg) < 0)
 175                                 errexit("unsupported board");
 176                         break;
 177                 case 'v':
 178                         len = strlen(optarg);
 179                         if (len > sizeof(h.swVersionInt))
 180                                 errexit("version string too long");
 181                         memcpy(h.swVersionInt, optarg, len);
 182                         memcpy(h.swVersionExt, optarg, len);
 183                         break;
 184                 case 'i':
 185                         input_file = map_input(optarg, &file_len);
 186                         if (!input_file)
 187                                 errexit(optarg);
 188                         break;
 189                 case 'o':
 190                         fdout = open(optarg, O_WRONLY | O_CREAT, 0644);
 191                         if (fdout < 0)
 192                                 errexit(optarg);
 193                         break;
 194                 default:
 195                         usage(argv[0]);
 196                 }
 197         }
 198
 199         /* required paremeters */
 200         if (!input_file || !h.modelid || !h.swVersionInt[0])
 201                 usage(argv[0]);
 202
 203         /* length fields */
 204         h.len_t = htonl(sizeof(h) + file_len);
 205         h.len_p = htonl(file_len);
 206
 207         /* crc fields */
 208         init_crc32();
 209         crc = crc32buf(input_file, file_len);
 210         h.crc32_p = htonl(~crc);
 211         crc = crc32buf((unsigned char *)&h, sizeof(h));
 212         h.crc32_h = htonl(~crc);
 213
 214         /* dump new image */
 215         write(fdout, &h, sizeof(h));
 216         write(fdout, input_file, file_len);
 217
 218         /* close files */
 219         munmap(input_file, file_len);
 220         if (fdout != STDOUT_FILENO)
 221                 close(fdout);
 222
 223         return EXIT_SUCCESS;
 224 }