1 ecf69ddf 2022-10-20 op /*
  2 f31cd5a4 2023-01-16 op  * Copyright (c) 2022, 2023 Omar Polo <op@openbsd.org>
  3 50705614 2023-05-16 op  * Copyright (c) 2014 Reyk Floeter <reyk@openbsd.org>
  4 ecf69ddf 2022-10-20 op  *
  5 ecf69ddf 2022-10-20 op  * Permission to use, copy, modify, and distribute this software for any
  6 ecf69ddf 2022-10-20 op  * purpose with or without fee is hereby granted, provided that the above
  7 ecf69ddf 2022-10-20 op  * copyright notice and this permission notice appear in all copies.
  8 ecf69ddf 2022-10-20 op  *
  9 ecf69ddf 2022-10-20 op  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 10 ecf69ddf 2022-10-20 op  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 11 ecf69ddf 2022-10-20 op  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 12 ecf69ddf 2022-10-20 op  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 13 ecf69ddf 2022-10-20 op  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 14 ecf69ddf 2022-10-20 op  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 15 ecf69ddf 2022-10-20 op  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 16 ecf69ddf 2022-10-20 op  */
 17 ecf69ddf 2022-10-20 op 
 18 ecf69ddf 2022-10-20 op #include <ctype.h>
 19 ecf69ddf 2022-10-20 op #include <err.h>
 20 ecf69ddf 2022-10-20 op #include <errno.h>
 21 ecf69ddf 2022-10-20 op #include <stdio.h>
 22 ecf69ddf 2022-10-20 op #include <stdlib.h>
 23 ecf69ddf 2022-10-20 op #include <string.h>
 24 ecf69ddf 2022-10-20 op #include <time.h>
 25 ecf69ddf 2022-10-20 op #include <unistd.h>
 26 ecf69ddf 2022-10-20 op 
 27 ecf69ddf 2022-10-20 op #include <openssl/evp.h>
 28 ecf69ddf 2022-10-20 op #include <openssl/hmac.h>
 29 ecf69ddf 2022-10-20 op 
 30 ecf69ddf 2022-10-20 op #ifndef __OpenBSD__
 31 ecf69ddf 2022-10-20 op # define pledge(a, b) (0)
 32 ecf69ddf 2022-10-20 op #endif
 33 ecf69ddf 2022-10-20 op 
 34 ecf69ddf 2022-10-20 op #ifndef __dead
 35 ecf69ddf 2022-10-20 op # define __dead __attribute__((noreturn))
 36 ecf69ddf 2022-10-20 op #endif
 37 ecf69ddf 2022-10-20 op 
 38 9bf09c65 2023-05-16 op #if defined(__FreeBSD__) || defined(__NetBSD__)
 39 ecf69ddf 2022-10-20 op # include <sys/endian.h>
 40 ecf69ddf 2022-10-20 op #elif defined(__APPLE__)
 41 ecf69ddf 2022-10-20 op # include <machine/endian.h>
 42 ecf69ddf 2022-10-20 op # include <libkern/OSByteOrder.h>
 43 ecf69ddf 2022-10-20 op # define htobe64(x) OSSwapHostToBigInt64(x)
 44 ecf69ddf 2022-10-20 op # define be32toh(x) OSSwapBigToHostInt32(x)
 45 ecf69ddf 2022-10-20 op #else
 46 ecf69ddf 2022-10-20 op # include <endian.h>
 47 ecf69ddf 2022-10-20 op #endif
 48 ecf69ddf 2022-10-20 op 
 49 ecf69ddf 2022-10-20 op static __dead void
 50 ecf69ddf 2022-10-20 op usage(void)
 51 ecf69ddf 2022-10-20 op {
 52 ecf69ddf 2022-10-20 op 	fprintf(stderr, "usage: %s\n", getprogname());
 53 ecf69ddf 2022-10-20 op 	exit(1);
 54 ecf69ddf 2022-10-20 op }
 55 ecf69ddf 2022-10-20 op 
 56 ecf69ddf 2022-10-20 op static int
 57 ecf69ddf 2022-10-20 op b32c(unsigned char c)
 58 ecf69ddf 2022-10-20 op {
 59 ecf69ddf 2022-10-20 op 	if (c >= 'A' && c <= 'Z')
 60 ecf69ddf 2022-10-20 op 		return (c - 'A');
 61 ecf69ddf 2022-10-20 op 	if (c >= '2' && c <= '7')
 62 ecf69ddf 2022-10-20 op 		return (c - '2' + 26);
 63 ecf69ddf 2022-10-20 op 	errno = EINVAL;
 64 ecf69ddf 2022-10-20 op 	return (-1);
 65 ecf69ddf 2022-10-20 op }
 66 ecf69ddf 2022-10-20 op 
 67 ecf69ddf 2022-10-20 op static size_t
 68 cc5f172a 2022-10-25 op b32decode(const char *s, char *q, size_t qlen)
 69 ecf69ddf 2022-10-20 op {
 70 ecf69ddf 2022-10-20 op 	int	 i, val[8];
 71 ecf69ddf 2022-10-20 op 	char	*t = q;
 72 ecf69ddf 2022-10-20 op 
 73 cc5f172a 2022-10-25 op 	while (*s != '\0') {
 74 ecf69ddf 2022-10-20 op 		memset(val, 0, sizeof(val));
 75 ecf69ddf 2022-10-20 op 		for (i = 0; i < 8; ++i) {
 76 cc5f172a 2022-10-25 op 			if (*s == '\0')
 77 ecf69ddf 2022-10-20 op 				break;
 78 ecf69ddf 2022-10-20 op 			if ((val[i] = b32c(*s)) == -1)
 79 ecf69ddf 2022-10-20 op 				return (0);
 80 cc5f172a 2022-10-25 op 			s++;
 81 ecf69ddf 2022-10-20 op 		}
 82 ecf69ddf 2022-10-20 op 
 83 ecf69ddf 2022-10-20 op 		if (qlen < 5) {
 84 ecf69ddf 2022-10-20 op 			errno = ENOSPC;
 85 ecf69ddf 2022-10-20 op 			return (0);
 86 ecf69ddf 2022-10-20 op 		}
 87 ecf69ddf 2022-10-20 op 		qlen -= 5;
 88 ecf69ddf 2022-10-20 op 
 89 ecf69ddf 2022-10-20 op 		*q++ = (val[0] << 3) | (val[1] >> 2);
 90 ecf69ddf 2022-10-20 op 		*q++ = ((val[1] & 0x03) << 6) | (val[2] << 1) | (val[3] >> 4);
 91 ecf69ddf 2022-10-20 op 		*q++ = ((val[3] & 0x0F) << 4) | (val[4] >> 1);
 92 ecf69ddf 2022-10-20 op 		*q++ = ((val[4] & 0x01) << 7) | (val[5] << 2) | (val[6] >> 3);
 93 ecf69ddf 2022-10-20 op 		*q++ = ((val[6] & 0x07) << 5) | val[7];
 94 ecf69ddf 2022-10-20 op 	}
 95 ecf69ddf 2022-10-20 op 
 96 ecf69ddf 2022-10-20 op 	return (q - t);
 97 ecf69ddf 2022-10-20 op }
 98 ecf69ddf 2022-10-20 op 
 99 50705614 2023-05-16 op /* adapted from httpd(8) */
100 50705614 2023-05-16 op static char *
101 50705614 2023-05-16 op url_decode(char *url, char *dst)
102 50705614 2023-05-16 op {
103 50705614 2023-05-16 op 	char		*p, *q;
104 50705614 2023-05-16 op 	char		 hex[3];
105 50705614 2023-05-16 op 	unsigned long	 x;
106 50705614 2023-05-16 op 
107 50705614 2023-05-16 op 	hex[2] = '\0';
108 50705614 2023-05-16 op 	p = url;
109 50705614 2023-05-16 op 	q = dst;
110 50705614 2023-05-16 op 
111 50705614 2023-05-16 op 	while (*p != '\0') {
112 50705614 2023-05-16 op 		if (*p != '%') {
113 50705614 2023-05-16 op 			*q++ = *p++;
114 50705614 2023-05-16 op 			continue;
115 50705614 2023-05-16 op 		}
116 50705614 2023-05-16 op 
117 50705614 2023-05-16 op 		if (!isxdigit((unsigned char)p[1]) ||
118 50705614 2023-05-16 op 		    !isxdigit((unsigned char)p[2]))
119 50705614 2023-05-16 op 			return (NULL);
120 50705614 2023-05-16 op 
121 50705614 2023-05-16 op 		hex[0] = p[1];
122 50705614 2023-05-16 op 		hex[1] = p[2];
123 50705614 2023-05-16 op 
124 50705614 2023-05-16 op 		/*
125 50705614 2023-05-16 op 		 * We don't have to validate "hex" because it is
126 50705614 2023-05-16 op 		 * guaranteed to include two hex chars followed by nul.
127 50705614 2023-05-16 op 		 */
128 50705614 2023-05-16 op 		x = strtoul(hex, NULL, 16);
129 50705614 2023-05-16 op 		*q++ = (char)x;
130 50705614 2023-05-16 op 		p += 3;
131 50705614 2023-05-16 op 	}
132 50705614 2023-05-16 op 	*q = '\0';
133 50705614 2023-05-16 op 	return (url);
134 50705614 2023-05-16 op }
135 50705614 2023-05-16 op 
136 f31cd5a4 2023-01-16 op static int
137 efd5f30c 2023-05-21 op uri2secret(char *s, int *digits)
138 f31cd5a4 2023-01-16 op {
139 44703d29 2023-05-16 op 	char		*q, *t, *f, *secret = NULL;
140 f31cd5a4 2023-01-16 op 
141 f31cd5a4 2023-01-16 op 	if ((q = strchr(s, '?')) == NULL)
142 f31cd5a4 2023-01-16 op 		return (-1);
143 44703d29 2023-05-16 op 
144 44703d29 2023-05-16 op 	t = q + 1;
145 44703d29 2023-05-16 op 	while ((f = strsep(&t, "&")) != NULL) {
146 44703d29 2023-05-16 op 		if (!strncmp(f, "secret=", 7))
147 44703d29 2023-05-16 op 			secret = f + 7;
148 efd5f30c 2023-05-21 op 		else if (!strncmp(f, "digits=", 7)) {
149 efd5f30c 2023-05-21 op 			f += 7;
150 efd5f30c 2023-05-21 op 			if (!strcmp(f, "6"))
151 efd5f30c 2023-05-21 op 				*digits = 6;
152 efd5f30c 2023-05-21 op 			else if (!strcmp(f, "7"))
153 efd5f30c 2023-05-21 op 				*digits = 7;
154 efd5f30c 2023-05-21 op 			else if (!strcmp(f, "8"))
155 efd5f30c 2023-05-21 op 				*digits = 8;
156 efd5f30c 2023-05-21 op 			else
157 efd5f30c 2023-05-21 op 				warnx("invalid number of digits; using 6");
158 efd5f30c 2023-05-21 op 		}
159 44703d29 2023-05-16 op 	}
160 44703d29 2023-05-16 op 
161 44703d29 2023-05-16 op 	if (secret == NULL)
162 f31cd5a4 2023-01-16 op 		return (-1);
163 50705614 2023-05-16 op 	if (url_decode(secret, s) == NULL)
164 50705614 2023-05-16 op 		errx(1, "failed to percent-decode the secret");
165 f31cd5a4 2023-01-16 op 	return (0);
166 f31cd5a4 2023-01-16 op }
167 f31cd5a4 2023-01-16 op 
168 ecf69ddf 2022-10-20 op int
169 ecf69ddf 2022-10-20 op main(int argc, char **argv)
170 ecf69ddf 2022-10-20 op {
171 ecf69ddf 2022-10-20 op 	char		 buf[1024];
172 ecf69ddf 2022-10-20 op 	size_t		 buflen;
173 ecf69ddf 2022-10-20 op 	unsigned char	 md[EVP_MAX_MD_SIZE];
174 ecf69ddf 2022-10-20 op 	unsigned int	 mdlen;
175 ecf69ddf 2022-10-20 op 	char		*s, *q, *line = NULL;
176 ecf69ddf 2022-10-20 op 	size_t		 linesize = 0;
177 ecf69ddf 2022-10-20 op 	ssize_t		 linelen;
178 ecf69ddf 2022-10-20 op 	uint64_t	 ct;
179 ecf69ddf 2022-10-20 op 	uint32_t	 hash;
180 ecf69ddf 2022-10-20 op 	uint8_t		 off;
181 efd5f30c 2023-05-21 op 	int		 ch, digits = 6;
182 ecf69ddf 2022-10-20 op 
183 ecf69ddf 2022-10-20 op 	if (pledge("stdio", NULL) == -1)
184 ecf69ddf 2022-10-20 op 		err(1, "pledge");
185 ecf69ddf 2022-10-20 op 
186 ecf69ddf 2022-10-20 op 	while ((ch = getopt(argc, argv, "")) != -1) {
187 ecf69ddf 2022-10-20 op 		switch (ch) {
188 ecf69ddf 2022-10-20 op 		default:
189 ecf69ddf 2022-10-20 op 			usage();
190 ecf69ddf 2022-10-20 op 		}
191 ecf69ddf 2022-10-20 op 	}
192 ecf69ddf 2022-10-20 op 	argc -= optind;
193 ecf69ddf 2022-10-20 op 	argv += optind;
194 ecf69ddf 2022-10-20 op 
195 ecf69ddf 2022-10-20 op 	if (argc != 0)
196 ecf69ddf 2022-10-20 op 		usage();
197 ecf69ddf 2022-10-20 op 
198 ecf69ddf 2022-10-20 op 	linelen = getline(&line, &linesize, stdin);
199 ecf69ddf 2022-10-20 op 	if (linelen == -1) {
200 ecf69ddf 2022-10-20 op 		if (ferror(stdin))
201 ecf69ddf 2022-10-20 op 			err(1, "getline");
202 ecf69ddf 2022-10-20 op 		errx(1, "no secret provided");
203 ecf69ddf 2022-10-20 op 	}
204 ecf69ddf 2022-10-20 op 	for (s = q = line; *s != '\0'; ++s) {
205 ecf69ddf 2022-10-20 op 		if (isspace((unsigned char)*s)) {
206 ecf69ddf 2022-10-20 op 			linelen--;
207 ecf69ddf 2022-10-20 op 			continue;
208 ecf69ddf 2022-10-20 op 		}
209 ecf69ddf 2022-10-20 op 		*q++ = *s;
210 ecf69ddf 2022-10-20 op 	}
211 ecf69ddf 2022-10-20 op 	*q = '\0';
212 ecf69ddf 2022-10-20 op 	if (linelen < 1)
213 ecf69ddf 2022-10-20 op 		errx(1, "no secret provided");
214 ecf69ddf 2022-10-20 op 
215 efd5f30c 2023-05-21 op 	if (!strncmp(line, "otpauth://", 10) &&
216 efd5f30c 2023-05-21 op 	    uri2secret(line, &digits) == -1)
217 f31cd5a4 2023-01-16 op 		errx(1, "failed to decode otpauth URI");
218 f31cd5a4 2023-01-16 op 
219 cc5f172a 2022-10-25 op 	if ((buflen = b32decode(line, buf, sizeof(buf))) == 0)
220 ecf69ddf 2022-10-20 op 		err(1, "can't base32 decode the secret");
221 ecf69ddf 2022-10-20 op 
222 ecf69ddf 2022-10-20 op 	ct = htobe64(time(NULL) / 30);
223 ecf69ddf 2022-10-20 op 
224 ecf69ddf 2022-10-20 op 	HMAC(EVP_sha1(), buf, buflen, (unsigned char *)&ct, sizeof(ct),
225 ecf69ddf 2022-10-20 op 	    md, &mdlen);
226 ecf69ddf 2022-10-20 op 
227 ecf69ddf 2022-10-20 op 	off = md[mdlen - 1] & 0x0F;
228 ecf69ddf 2022-10-20 op 
229 ecf69ddf 2022-10-20 op 	memcpy(&hash, md + off, sizeof(hash));
230 ecf69ddf 2022-10-20 op 	hash = be32toh(hash);
231 ecf69ddf 2022-10-20 op 
232 efd5f30c 2023-05-21 op 	switch (digits) {
233 efd5f30c 2023-05-21 op 	case 6:
234 efd5f30c 2023-05-21 op 		printf("%06d\n", (hash & 0x7FFFFFFF) % 1000000);
235 efd5f30c 2023-05-21 op 		break;
236 efd5f30c 2023-05-21 op 	case 7:
237 efd5f30c 2023-05-21 op 		printf("%07d\n", (hash & 0x7FFFFFFF) % 10000000);
238 efd5f30c 2023-05-21 op 		break;
239 efd5f30c 2023-05-21 op 	case 8:
240 efd5f30c 2023-05-21 op 		printf("%08d\n", (hash & 0x7FFFFFFF) % 100000000);
241 efd5f30c 2023-05-21 op 		break;
242 efd5f30c 2023-05-21 op 	}
243 efd5f30c 2023-05-21 op 
244 ecf69ddf 2022-10-20 op 	free(line);
245 ecf69ddf 2022-10-20 op 	return (0);
246 ecf69ddf 2022-10-20 op }