-
Notifications
You must be signed in to change notification settings - Fork 3
/
spaclient.c
569 lines (498 loc) · 15.3 KB
/
spaclient.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <stddef.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include <unistd.h>
#include <netdb.h>
#include <openssl/sha.h>
#include <openssl/aes.h>
#include <openssl/hmac.h>
#include "common.h"
union uint32_u
{
uint32_t u32;
uint8_t u8[4];
};
struct spa_config
{
struct sockaddr_in server_address;
char key[MAX_KEY_SIZE+1];
size_t key_len;
uint8_t request[BITS_TO_BYTES(MAX_REQUEST_BITS)];
size_t request_len;
enum {IGNORE_CLIENT_ADDRESS, MANUAL_CLIENT_ADDRESS, AUTO_CLIENT_ADDRESS} client_address_mode;
in_addr_t client_address;
};
struct spa_challenge
{
uint16_t port;
uint16_t nonce_len;
uint8_t nonce[BITS_TO_BYTES(MAX_CHALLENGE_BITS)];
};
/*****************************
getline(FILE*)
Reads in a line of input from a file, storing it in a dynamically-allocated
string
Params: FILE* file - the file to read from
Returns: a string containing the line. Must be freed with free()
Effects: I/O
*/
__attribute__((__unused__)) static char*
getLine(FILE* file, int stripnl)
{
char* ptr = NULL;
char* nptr = NULL;
size_t len = 0;
#define LINE_SIZE 80
size_t size = LINE_SIZE;
size_t oldsize = 0;
do
{
/* allocate an appropriately-sized buffer */
nptr = realloc(ptr, size+1);
if (nptr == NULL)
{
free(ptr);
return NULL;
}
ptr = nptr;
/* read into the buffer */
fgets(&ptr[oldsize], size-oldsize+1, file);
len = strlen(ptr);
if (size > (UINT_MAX/2))
return ptr;
oldsize = size;
size*=2;
} while (ptr[len-1] != '\n');
/* remove trailing newline */
if (stripnl)
ptr[len-1] = '\0';
return ptr;
}
/* addr must be in network byte order */
/*static char*
ipv4_to_string(char buf[16], in_addr_t addr)
{
union uint32_u u;
u.u32 = addr;
snprintf(buf, 16, "%hhu.%hhu.%hhu.%hhu", u.u8[0], u.u8[1], u.u8[2], u.u8[3]);
return buf;
}*/
static uint8_t
hextobin(char c)
{
switch (c)
{
case '0':
return 0; break;
case '1':
return 1; break;
case '2':
return 2; break;
case '3':
return 3; break;
case '4':
return 4; break;
case '5':
return 5; break;
case '6':
return 6; break;
case '7':
return 7; break;
case '8':
return 8; break;
case '9':
return 9; break;
case 'a': case 'A':
return 10; break;
case 'b': case 'B':
return 11; break;
case 'c': case 'C':
return 12; break;
case 'd': case 'D':
return 13; break;
case 'e': case 'E':
return 14; break;
case 'f': case 'F':
return 15; break;
default:
return UINT8_MAX;
}
}
static void
print_config(const struct spa_config* config, FILE* file)
{
unsigned i;
fprintf(file, "Server: %s/%hu\n", inet_ntoa(config->server_address.sin_addr), ntohs(config->server_address.sin_port));
fputs("Request: 0x", file);
for (i=0; i<config->request_len; i++)
fprintf(file, "%hhx", config->request[i]);
fputc('\n', file);
fprintf(file, "Key: %s\n", config->key);
}
static int
get_config_cmdl(struct spa_config* config, const int argc, const char** argv)
{
struct hostent* host;
char* ptr;
unsigned long tmp;
size_t len;
unsigned i;
uint8_t high, low;
if (argc != 5)
{
fprintf(stderr, "Usage: %s <host> <port> <request> <key>\n", argv[0]);
return -1;
}
/* get the server address */
host = gethostbyname(argv[1]);
if (host == NULL)
{
fprintf(stderr, "Error resolving host %s: %s\n", argv[1], hstrerror(h_errno));
return -1;
}
if ((host->h_addrtype != AF_INET) || (host->h_length != 4) || (host->h_addr_list[0] == NULL))
{
fprintf(stderr, "Unexpected result from gethostbyname()");
return -1;
}
config->server_address.sin_addr.s_addr = *((in_addr_t*)host->h_addr_list[0]);
/* get the server port number */
tmp = strtoul(argv[2], &ptr, 10);
if ((*ptr != '\0') || (tmp > 65535))
{
fprintf(stderr, "Invalid port number: %s\n", argv[2]);
return -1;
}
config->server_address.sin_port = htons(tmp);
/* get the request string */
len = strlen(argv[3]);
i = 0;
if ((len >= 2) && (argv[3][0] == '0') && (argv[3][1] == 'x'))
i = 2;
if ((len-i+1)*4 < MIN_REQUEST_BITS)
{
fprintf(stderr, "Error: request too short\n");
return -1;
}
else if ((len-i+1)*4 > MAX_REQUEST_BITS)
{
fprintf(stderr, "Error: request too long\n");
return -1;
}
else
{
config->request_len = 0;
if ((len-i) & 0x00000001)
{
/* handle the first character separately */
low = hextobin(argv[3][i++]);
config->request[config->request_len++] = low;
}
for (; i<len; i+=2)
{
high = hextobin(argv[3][i]);
low = hextobin(argv[3][i+1]);
if ((high == UINT8_MAX) || (low == UINT8_MAX))
{
fprintf(stderr, "Error: invalid character in request string\n");
return -1;
}
config->request[config->request_len++] = (high<<4)|low;
}
}
/* get the key */
if (strlen(argv[4]) < MIN_KEY_SIZE)
{
fprintf(stderr, "Error: key too short\n");
return -1;
}
else if (strlen(argv[4]) > MAX_KEY_SIZE)
{
fprintf(stderr, "Error: key too long\n");
return -1;
}
config->key_len = strlen(argv[4]);
strncpy(config->key, argv[4], config->key_len);
return 0;
}
static int
get_config_term(struct spa_config* UNUSED(config))
{
fprintf(stderr, "Error: interactive mode not yet implemented\n");
return -1;
}
static int
get_config(struct spa_config* config, const int argc, const char** argv)
{
/* common initialization */
memset(config, 0, sizeof(struct spa_config));
config->server_address.sin_family = AF_INET;
if (argc > 1)
return get_config_cmdl(config, argc, argv);
else
return get_config_term(config);
}
static int
open_socket(const struct spa_config* config)
{
int sock;
int retval;
struct sockaddr_in addr;
/* open */
sock = socket(PF_INET, SOCK_DGRAM, 0);
if (sock == -1)
{
fprintf(stderr, "Error opening socket: %s\n", strerror(errno));
return -1;
}
/* bind */
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = 0;
addr.sin_addr.s_addr = htonl(INADDR_ANY);
retval = bind(sock, (struct sockaddr*)&addr, sizeof(addr));
if (retval == -1)
{
fprintf(stderr, "Error binding socket: %s\n", strerror(errno));
return -1;
}
/* connect */
retval = connect(sock, (struct sockaddr*)&config->server_address, sizeof(config->server_address));
if (retval == -1)
{
fprintf(stderr, "Error connecting socket: %s\n", strerror(errno));
return -1;
}
/* FIXME: get local address here */
return sock;
}
static int
send_request(int sock, const struct spa_config* config)
{
uint8_t* message;
size_t len;
ssize_t retval;
assert(config != NULL);
/* build the request message */
len = sizeof(struct SpaRequestHeader) + config->request_len;
message = malloc(len);
if (message == NULL)
{
fprintf(stderr, "Error: out of memory\n");
return -1;
}
memset(message, 0, sizeof(struct SpaRequestHeader));
((struct SpaRequestHeader*)message)->requestBytes = htons(config->request_len);
memcpy(message+sizeof(struct SpaRequestHeader), config->request, config->request_len);
/* send the request */
retval = send(sock, message, len, 0);
if (retval == -1)
{
fprintf(stderr, "Error sending request: %s\n", strerror(errno));
free(message);
return -1;
}
else if (retval != (ssize_t)len)
{
fprintf(stderr, "Error sending request: message truncated\n");
free(message);
return -1;
}
free(message);
return 0;
}
static int decrypt_port(uint16_t* port, const uint8_t* buf, const char* key, size_t keylen)
{
uint8_t hash[BITS_TO_BYTES(HASH_BITS)];
struct PortMessage message;
AES_KEY ctx;
int retval;
assert(sizeof(struct PortMessage)*8 == CIPHER_BLOCK_BITS);
assert(HASH_BITS >= PORT_MESSAGE_HASH_BITS);
assert(HASH_BITS >= CIPHER_KEY_BITS);
/* generate the decryption key */
SHA1((unsigned char*)key, keylen, hash);
/* decrypt the message */
retval = AES_set_decrypt_key(hash, 128, &ctx);
if (retval)
{
fprintf(stderr, "Error setting decryption key\n");
return -1;
}
AES_ecb_encrypt(buf, (unsigned char*)&message, &ctx, AES_DECRYPT);
/* verify the hash */
SHA1((unsigned char*)&message, offsetof(struct PortMessage, hash), hash);
if (memcmp(hash, message.hash, sizeof(message.hash)))
{
fprintf(stderr, "Error verifying challenge hash\n");
return -1;
}
#ifdef DEBUG
fprintf(stderr, "received challenge, dport=%hu\n", ntohs(message.port));
#endif
*port = ntohs(message.port);
return 0;
}
static int
receive_challenge(int sock, struct spa_challenge* challenge, const struct spa_config* config)
{
uint8_t buf[sizeof(struct ChallengeHeader)+BITS_TO_BYTES(MAX_CHALLENGE_BITS)];
int retval;
ssize_t bytes;
struct timeval timeout;
assert(challenge != NULL);
assert(config != NULL);
/* set the socket timeout */
timeout.tv_sec = TIMEOUT_SECS;
timeout.tv_usec = TIMEOUT_USECS;
retval = setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));
if (retval == -1)
{
fprintf(stderr, "Error setting socket timeout: %s\n", strerror(errno));
return -1;
}
/* receive the message */
bytes = recv(sock, buf, sizeof(buf), 0);
if (bytes == -1)
{
if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
fprintf(stderr, "Timeout waiting for server response\n");
else
fprintf(stderr, "Error receiving challenge: %s\n", strerror(errno));
return -1;
}
/* parse the message */
if ((bytes < 0) || ((size_t)bytes < sizeof(struct ChallengeHeader)))
{
fprintf(stderr, "Error receiving challenge: message truncated\n");
return -1;
}
struct ChallengeHeader *header = (struct ChallengeHeader*)buf;
uint16_t nonce_len = ntohs(header->nonceBytes);
if (bytes != (int)(sizeof(struct ChallengeHeader)+nonce_len))
{
fprintf(stderr, "Error receiving challenge: message truncated\n");
return -1;
}
challenge->nonce_len = nonce_len;
memcpy(challenge->nonce, buf+sizeof(struct ChallengeHeader), challenge->nonce_len);
retval = decrypt_port(&challenge->port, buf+offsetof(struct ChallengeHeader, portMessage), config->key, config->key_len);
if (retval)
return -1; /* error message already logged */
return 0;
}
static int compute_mac(uint8_t* mac, int sock, const struct spa_challenge* challenge, const struct spa_config* config)
{
uint8_t* buf;
size_t buflen;
union uint32_u u;
struct sockaddr_in addr;
socklen_t addr_len;
int retval;
uint8_t key[BITS_TO_BYTES(HASH_BITS)];
assert(challenge != NULL);
assert(config != NULL);
/* allocate a buffer for the message */
buflen = challenge->nonce_len + sizeof(uint32_t) + sizeof(uint32_t) + config->request_len;
buf = malloc(buflen);
if (buf == NULL)
{
fprintf(stderr, "Error: out of memory\n");
return -1;
}
/* copy the challenge into the message */
memcpy(buf, challenge->nonce, challenge->nonce_len);
/* copy the client address into the message */
if (config->client_address_mode == IGNORE_CLIENT_ADDRESS)
u.u32 = 0;
else if (config->client_address_mode == MANUAL_CLIENT_ADDRESS)
u.u32 = config->client_address; /* already in NBO */
else
{
addr_len = sizeof(addr);
retval = getsockname(sock, (struct sockaddr*)&addr, &addr_len);
if (retval == -1)
{
fprintf(stderr, "Error retrieving socket address: %s\n", strerror(errno));
return -1;
}
printf("WARNING: Using auto-detected source address %s\n", inet_ntoa(addr.sin_addr));
printf("If this address is modified in transit by a NAT, authentication will fail.\n");
u.u32 = addr.sin_addr.s_addr; /* already in NBO */
}
memcpy(buf+challenge->nonce_len, u.u8, sizeof(uint32_t));
/* copy the server address into the message */
u.u32 = config->server_address.sin_addr.s_addr; /* already in NBO */
memcpy(buf+challenge->nonce_len+sizeof(uint32_t), u.u8, sizeof(uint32_t));
/* copy the request into the message */
memcpy(buf+challenge->nonce_len+2*sizeof(uint32_t), config->request, config->request_len);
/* generate the MAC key */
SHA1((unsigned char*)config->key, config->key_len, key);
/* generate the MAC */
HMAC(EVP_sha1(), key, BITS_TO_BYTES(HASH_BITS), buf, buflen, mac, NULL);
free(buf);
return 0;
}
static int
send_response(int sock, const struct spa_challenge* challenge, const struct spa_config* config)
{
uint8_t buf[BITS_TO_BYTES(HASH_BITS)];
int retval;
assert(challenge != NULL);
assert(config != NULL);
retval = compute_mac(buf, sock, challenge, config);
if (retval == -1)
return -1; /* error message already logged */
/* send the response */
retval = send(sock, buf, sizeof(buf), 0);
if (retval == -1)
{
fprintf(stderr, "Error sending response: %s\n", strerror(errno));
return -1;
}
else if (retval != (ssize_t)sizeof(buf))
{
fprintf(stderr, "Error sending response: message truncated\n");
return -1;
}
return 0;
}
int
main(int argc, const char** argv)
{
struct spa_config config;
struct spa_challenge challenge;
int retval;
int sock;
retval = get_config(&config, argc, argv);
if (retval)
exit(EXIT_FAILURE); /* error message already printed */
print_config(&config, stdout);
/* FIXME: set client address mode properly */
config.client_address_mode = AUTO_CLIENT_ADDRESS;
sock = open_socket(&config);
if (sock == -1)
exit(EXIT_FAILURE); /* error message already printed */
retval = send_request(sock, &config);
if (retval)
exit(EXIT_FAILURE); /* error message already printed */
retval = receive_challenge(sock, &challenge, &config);
if (retval)
exit(EXIT_FAILURE); /* error message already logged */
retval = send_response(sock, &challenge, &config);
if (retval)
exit(EXIT_FAILURE); /* error message already logged */
printf("Authentication complete; port = %hu\n", challenge.port);
/* clean up */
memset(&config, 0, sizeof(config));
close(sock);
return EXIT_SUCCESS;
}