97b5f1d4558aa7c2abc00ddab43c8547e68fcdc3
[openwrt/svn-archive/archive.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 #define WNDR3700_MAGIC_LEN 4
41
42 static uint32_t crc32[1<<BPB];
43 static char *magic = "3700";
44
45 static void init_crc32()
46 {
47 const uint32_t poly = ntohl(0x2083b8ed);
48 int n;
49
50 for (n = 0; n < 1<<BPB; n++) {
51 uint32_t crc = n;
52 int bit;
53
54 for (bit = 0; bit < BPB; bit++)
55 crc = (crc & 1) ? (poly ^ (crc >> 1)) : (crc >> 1);
56 crc32[n] = crc;
57 }
58 }
59
60 static uint32_t crc32buf(unsigned char *buf, size_t len)
61 {
62 uint32_t crc = 0xFFFFFFFF;
63
64 for (; len; len--, buf++)
65 crc = crc32[(uint8_t)crc ^ *buf] ^ (crc >> BPB);
66 return ~crc;
67 }
68
69 struct header {
70 unsigned char magic[WNDR3700_MAGIC_LEN];
71 uint32_t crc;
72 unsigned char stuff[56];
73 };
74
75 static void usage(const char *) __attribute__ (( __noreturn__ ));
76
77 static void usage(const char *mess)
78 {
79 fprintf(stderr, "Error: %s\n", mess);
80 fprintf(stderr, "Usage: wndr3700 input_file output_file [magic]\n");
81 fprintf(stderr, "\n");
82 exit(1);
83 }
84
85 int main(int argc, char **argv)
86 {
87 off_t len; // of original buf
88 off_t buflen; // of the output file
89 int fd;
90 void *input_file; // pointer to the input file (mmmapped)
91 struct header header;
92 unsigned char *buf; // pointer to prefix + copy of original buf
93
94 // verify parameters
95
96 if (argc < 3)
97 usage("wrong number of arguments");
98
99 if (argc > 3)
100 magic = argv[3];
101
102 if (strlen(magic) != WNDR3700_MAGIC_LEN) {
103 fprintf(stderr, "Invalid magic: '%s'\n", magic);
104 exit(1);
105 }
106
107 // mmap input_file
108 if ((fd = open(argv[1], O_RDONLY)) < 0
109 || (len = lseek(fd, 0, SEEK_END)) < 0
110 || (input_file = mmap(0, len, PROT_READ, MAP_SHARED, fd, 0)) == (void *) (-1)
111 || close(fd) < 0)
112 {
113 fprintf(stderr, "Error loading file %s: %s\n", argv[1], strerror(errno));
114 exit(1);
115 }
116
117 buflen = len;
118
119 init_crc32();
120
121 // preload header
122 memcpy(&header, input_file, sizeof(header));
123
124 memcpy(header.magic, magic, WNDR3700_MAGIC_LEN);
125 header.crc = 0;
126
127 // create a firmware image in memory and copy the input_file to it
128 buf = malloc(buflen);
129 memcpy(buf, input_file, len);
130
131 // CRC of temporary header
132 header.crc = htonl(crc32buf((unsigned char*)&header, sizeof(header)));
133
134 memcpy(buf, &header, sizeof(header));
135
136 // write the buf
137 if ((fd = open(argv[2], O_CREAT|O_WRONLY|O_TRUNC,0644)) < 0
138 || write(fd, buf, buflen) != buflen
139 || close(fd) < 0)
140 {
141 fprintf(stderr, "Error storing file %s: %s\n", argv[2], strerror(errno));
142 exit(2);
143 }
144
145 free(buf);
146
147 munmap(input_file,len);
148
149 return 0;
150 }