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Sources/firmware-utils/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 }
225 

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