51e5352cb0362b4004b241555ad718f0d83aa8f3
[openwrt/openwrt.git] / tools / firmware-utils / src / wndr3700.c
1 /*
2 * wndr3700.c - partially based on OpenWrt's add_header.c
3 *
4 * Copyright (C) 2009 Anael Orlinski <naouel@naouel.org>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License,
8 * version 2 as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18 */
19
20 /*
21 * The add_header utility used by various vendors preprends the buf
22 * image with a header containing a CRC32 value which is generated for the
23 * model id + reserved space for CRC32 + buf, then replaces the reserved
24 * area with the actual CRC32. This replacement tool mimics this behavior.
25 */
26
27 #include <stdio.h>
28 #include <stdlib.h>
29 #include <stddef.h>
30 #include <unistd.h>
31 #include <errno.h>
32 #include <fcntl.h>
33 #include <sys/mman.h>
34 #include <string.h>
35 #include <netinet/in.h>
36 #include <inttypes.h>
37
38 #define BPB 8 /* bits/byte */
39
40 static uint32_t crc32[1<<BPB];
41
42 static void init_crc32()
43 {
44 const uint32_t poly = ntohl(0x2083b8ed);
45 int n;
46
47 for (n = 0; n < 1<<BPB; n++) {
48 uint32_t crc = n;
49 int bit;
50
51 for (bit = 0; bit < BPB; bit++)
52 crc = (crc & 1) ? (poly ^ (crc >> 1)) : (crc >> 1);
53 crc32[n] = crc;
54 }
55 }
56
57 static uint32_t crc32buf(unsigned char *buf, size_t len)
58 {
59 uint32_t crc = 0xFFFFFFFF;
60
61 for (; len; len--, buf++)
62 crc = crc32[(uint8_t)crc ^ *buf] ^ (crc >> BPB);
63 return ~crc;
64 }
65
66 struct header {
67 uint32_t magic;
68 uint32_t crc;
69 unsigned char stuff[56];
70 };
71
72 static void usage(const char *) __attribute__ (( __noreturn__ ));
73
74 static void usage(const char *mess)
75 {
76 fprintf(stderr, "Error: %s\n", mess);
77 fprintf(stderr, "Usage: wndr3700 input_file output_file\n");
78 fprintf(stderr, "\n");
79 exit(1);
80 }
81
82 int main(int argc, char **argv)
83 {
84 off_t len; // of original buf
85 off_t buflen; // of the output file
86 int fd;
87 void *input_file; // pointer to the input file (mmmapped)
88 struct header header;
89 unsigned char *buf; // pointer to prefix + copy of original buf
90
91 // verify parameters
92
93 if (argc != 3)
94 usage("wrong number of arguments");
95
96 // mmap input_file
97 if ((fd = open(argv[1], O_RDONLY)) < 0
98 || (len = lseek(fd, 0, SEEK_END)) < 0
99 || (input_file = mmap(0, len, PROT_READ, MAP_SHARED, fd, 0)) == (void *) (-1)
100 || close(fd) < 0)
101 {
102 fprintf(stderr, "Error loading file %s: %s\n", argv[1], strerror(errno));
103 exit(1);
104 }
105
106 buflen = len;
107
108 init_crc32();
109
110 // preload header
111 memcpy(&header, input_file, sizeof(header));
112
113 header.magic = htonl(0x33373030); /* 3700 in ascii */
114 header.crc = 0;
115
116 // create a firmware image in memory and copy the input_file to it
117 buf = malloc(buflen);
118 memcpy(buf, input_file, len);
119
120 // CRC of temporary header
121 header.crc = htonl(crc32buf((unsigned char*)&header, sizeof(header)));
122
123 memcpy(buf, &header, sizeof(header));
124
125 // write the buf
126 if ((fd = open(argv[2], O_CREAT|O_WRONLY|O_TRUNC,0644)) < 0
127 || write(fd, buf, buflen) != buflen
128 || close(fd) < 0)
129 {
130 fprintf(stderr, "Error storing file %s: %s\n", argv[2], strerror(errno));
131 exit(2);
132 }
133
134 free(buf);
135
136 munmap(input_file,len);
137
138 return 0;
139 }