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         { "MT7621A", "LTE3301-PLUS", 0x03030001  },
  96         {}
  97 };
  98
  99 static int find_board(struct zytrx_t *h, char *board)
 100 {
 101         struct board_t *p;
 102
 103         for (p = boards; p->modelid; p++) {
 104                 if (strncmp((const char *)p->boardid, board, sizeof(p->boardid)))
 105                         continue;
 106                 memcpy(h->chipid, p->chipid, sizeof(h->chipid));
 107                 memcpy(h->boardid, p->boardid, sizeof(h->boardid));
 108                 h->modelid = htonl(p->modelid);
 109                 return 0;
 110         }
 111         return -1;
 112 }
 113
 114 static void usage(const char *name)
 115 {
 116         struct board_t *p;
 117
 118         fprintf(stderr, "Usage:\n");
 119         fprintf(stderr, " %s -B <board> -v <versionstr> -i <file> [-o <outputfile>]\n\n", name);
 120         fprintf(stderr, "Supported <board> values:\n");
 121         for (p = boards; p->modelid; p++)
 122                 fprintf(stderr, "\t%-12s\n", p->boardid);
 123         fprintf(stderr, "\nExample:\n");
 124         fprintf(stderr, " %s -B %s -v foobar-1.0 -i my.img -o out.img\n\n", name,
 125                 boards[0].boardid);
 126         exit(EXIT_FAILURE);
 127 }
 128
 129 static void errexit(const char *msg)
 130 {
 131         fprintf(stderr, "ERR: %s: %s\n", msg, errno ? strerror(errno) : "unknown");
 132         exit(EXIT_FAILURE);
 133 }
 134
 135 static void *map_input(const char *name, size_t *len)
 136 {
 137         struct stat stat;
 138         void *mapped;
 139         int fd;
 140
 141         fd = open(name, O_RDONLY);
 142         if (fd < 0)
 143                 return NULL;
 144         if (fstat(fd, &stat) < 0) {
 145                 close(fd);
 146                 return NULL;
 147         }
 148         *len = stat.st_size;
 149         mapped = mmap(NULL, stat.st_size, PROT_READ, MAP_SHARED, fd, 0);
 150         if (close(fd) < 0) {
 151                 (void) munmap(mapped, stat.st_size);
 152                 return NULL;
 153         }
 154         return mapped;
 155 }
 156
 157 int main(int argc, char **argv)
 158 {
 159         int c, fdout = STDOUT_FILENO;
 160         void *input_file = NULL;
 161         size_t file_len, len;
 162         uint32_t crc;
 163         struct zytrx_t h = {
 164                 .magic          = htonl(MAGIC),
 165                 .len_h          = htonl(sizeof(h)),
 166                 .verInt         = VER_INT,
 167                 .verExt         = VER_EXT,
 168                 .code           = CODE,
 169                 .kernelChksum   = htonl(KERNELCHKSUM),
 170         };
 171
 172         while ((c = getopt(argc, argv, "B:v:i:o:")) != -1) {
 173                 switch (c) {
 174                 case 'B':
 175                         if (find_board(&h, optarg) < 0)
 176                                 errexit("unsupported board");
 177                         break;
 178                 case 'v':
 179                         len = strlen(optarg);
 180                         if (len > sizeof(h.swVersionInt))
 181                                 errexit("version string too long");
 182                         memcpy(h.swVersionInt, optarg, len);
 183                         memcpy(h.swVersionExt, optarg, len);
 184                         break;
 185                 case 'i':
 186                         input_file = map_input(optarg, &file_len);
 187                         if (!input_file)
 188                                 errexit(optarg);
 189                         break;
 190                 case 'o':
 191                         fdout = open(optarg, O_WRONLY | O_CREAT, 0644);
 192                         if (fdout < 0)
 193                                 errexit(optarg);
 194                         break;
 195                 default:
 196                         usage(argv[0]);
 197                 }
 198         }
 199
 200         /* required paremeters */
 201         if (!input_file || !h.modelid || !h.swVersionInt[0])
 202                 usage(argv[0]);
 203
 204         /* length fields */
 205         h.len_t = htonl(sizeof(h) + file_len);
 206         h.len_p = htonl(file_len);
 207
 208         /* crc fields */
 209         init_crc32();
 210         crc = crc32buf(input_file, file_len);
 211         h.crc32_p = htonl(~crc);
 212         crc = crc32buf((unsigned char *)&h, sizeof(h));
 213         h.crc32_h = htonl(~crc);
 214
 215         /* dump new image */
 216         write(fdout, &h, sizeof(h));
 217         write(fdout, input_file, file_len);
 218
 219         /* close files */
 220         munmap(input_file, file_len);
 221         if (fdout != STDOUT_FILENO)
 222                 close(fdout);
 223
 224         return EXIT_SUCCESS;
 225 }