Root/package/network/utils/maccalc/src/main.c

1/*
2 * MAC address manupulation utility
3 *
4 * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 as published
8 * by the Free Software Foundation.
9 *
10 */
11
12#include <errno.h>
13#include <stdlib.h>
14#include <stdio.h>
15#include <stdint.h>
16#include <string.h>
17#include <unistd.h>
18
19#define MAC_ADDRESS_LEN 6
20
21#define ERR_INVALID 1
22#define ERR_IO 2
23
24static void usage(void);
25
26char *maccalc_name;
27
28static int parse_mac(const char *mac_str, unsigned char *buf)
29{
30    int t;
31
32    t = sscanf(mac_str, "%02hhx:%02hhx:%02hhx:%02hhx:%02hhx:%02hhx",
33           &buf[0], &buf[1], &buf[2], &buf[3], &buf[4], &buf[5]);
34
35    if (t != MAC_ADDRESS_LEN)
36        return ERR_INVALID;
37
38    return 0;
39}
40
41static void print_mac(unsigned char *buf)
42{
43    printf("%02x:%02x:%02x:%02x:%02x:%02x\n",
44           buf[0], buf[1], buf[2], buf[3], buf[4], buf[5]);
45}
46
47static int maccalc_do_add(int argc, const char *argv[])
48{
49    unsigned char mac[MAC_ADDRESS_LEN];
50    uint32_t t;
51    int err;
52    int i;
53
54    if (argc != 2) {
55        usage();
56        return ERR_INVALID;
57    }
58
59    err = parse_mac(argv[0], mac);
60    if (err)
61        return err;
62
63    i = atoi(argv[1]);
64
65    t = (mac[3] << 16) | (mac[4] << 8) | mac[5];
66    t += i;
67    mac[3] = (t >> 16) & 0xff;
68    mac[4] = (t >> 8) & 0xff;
69    mac[5] = t & 0xff;
70
71    print_mac(mac);
72    return 0;
73}
74
75static int maccalc_do_logical(int argc, const char *argv[],
76                  unsigned char (*op)(unsigned char n1,
77                          unsigned char n2))
78{
79    unsigned char mac1[MAC_ADDRESS_LEN];
80    unsigned char mac2[MAC_ADDRESS_LEN];
81    int err;
82    int i;
83
84    if (argc != 2) {
85        usage();
86        return ERR_INVALID;
87    }
88
89    err = parse_mac(argv[0], mac1);
90    if (err)
91        return err;
92
93    err = parse_mac(argv[1], mac2);
94    if (err)
95        return err;
96
97    for (i = 0; i < MAC_ADDRESS_LEN; i++)
98        mac1[i] = op(mac1[i],mac2[i]);
99
100    print_mac(mac1);
101    return 0;
102}
103
104static int maccalc_do_mac2bin(int argc, const char *argv[])
105{
106    unsigned char mac[MAC_ADDRESS_LEN];
107    ssize_t c;
108    int err;
109
110    if (argc != 1) {
111        usage();
112        return ERR_INVALID;
113    }
114
115    err = parse_mac(argv[0], mac);
116    if (err)
117        return err;
118
119    c = write(STDOUT_FILENO, mac, sizeof(mac));
120    if (c != sizeof(mac)) {
121        fprintf(stderr, "failed to write to stdout\n");
122        return ERR_IO;
123    }
124
125    return 0;
126}
127
128static ssize_t read_safe(int fd, void *buf, size_t count)
129{
130    ssize_t total = 0;
131    ssize_t r;
132
133    while(count > 0) {
134        r = read(fd, buf, count);
135        if (r == 0)
136            /* EOF */
137            break;
138        if (r < 0) {
139            if (errno == EINTR)
140                /* interrupted by a signal, restart */
141                continue;
142            /* error */
143            total = -1;
144            break;
145        }
146
147        /* ok */
148        total += r;
149        count -= r;
150        buf += r;
151    }
152
153    return total;
154}
155
156static int maccalc_do_bin2mac(int argc, const char *argv[])
157{
158    unsigned char mac[MAC_ADDRESS_LEN];
159    ssize_t c;
160
161    if (argc != 0) {
162        usage();
163        return ERR_INVALID;
164    }
165
166    c = read_safe(STDIN_FILENO, mac, sizeof(mac));
167    if (c != sizeof(mac)) {
168        fprintf(stderr, "failed to read from stdin\n");
169        return ERR_IO;
170    }
171
172    print_mac(mac);
173    return 0;
174}
175
176static unsigned char op_or(unsigned char n1, unsigned char n2)
177{
178    return n1 | n2;
179}
180
181static int maccalc_do_or(int argc, const char *argv[])
182{
183    return maccalc_do_logical(argc, argv, op_or);
184}
185
186static unsigned char op_and(unsigned char n1, unsigned char n2)
187{
188    return n1 & n2;
189}
190
191static int maccalc_do_and(int argc, const char *argv[])
192{
193    return maccalc_do_logical(argc, argv, op_and);
194}
195
196static unsigned char op_xor(unsigned char n1, unsigned char n2)
197{
198    return n1 ^ n2;
199}
200
201static int maccalc_do_xor(int argc, const char *argv[])
202{
203    return maccalc_do_logical(argc, argv, op_xor);
204}
205
206static void usage(void)
207{
208    fprintf(stderr,
209        "Usage: %s <command>\n"
210        "valid commands:\n"
211        " add <mac> <number>\n"
212        " and|or|xor <mac1> <mac2>\n"
213        " mac2bin <mac>\n"
214        " bin2mac\n",
215        maccalc_name);
216}
217
218int main(int argc, const char *argv[])
219{
220    int (*op)(int argc, const char *argv[]);
221    int ret;
222
223    maccalc_name = (char *) argv[0];
224
225    if (argc < 2) {
226        usage();
227        return EXIT_FAILURE;
228    }
229
230    if (strcmp(argv[1], "add") == 0) {
231        op = maccalc_do_add;
232    } else if (strcmp(argv[1], "and") == 0) {
233        op = maccalc_do_and;
234    } else if (strcmp(argv[1], "or") == 0) {
235        op = maccalc_do_or;
236    } else if (strcmp(argv[1], "xor") == 0) {
237        op = maccalc_do_xor;
238    } else if (strcmp(argv[1], "mac2bin") == 0) {
239        op = maccalc_do_mac2bin;
240    } else if (strcmp(argv[1], "bin2mac") == 0) {
241        op = maccalc_do_bin2mac;
242    } else {
243        fprintf(stderr, "unknown command '%s'\n", argv[1]);
244        usage();
245        return EXIT_FAILURE;
246    }
247
248    argc -= 2;
249    argv += 2;
250
251    ret = op(argc, argv);
252    if (ret)
253        return EXIT_FAILURE;
254
255    return EXIT_SUCCESS;
256}
257

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