Source

PuTTY / misc.c

Full commit
  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
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
/*
 * Platform-independent routines shared between all PuTTY programs.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <limits.h>
#include <ctype.h>
#include <assert.h>
#include "putty.h"

/*
 * Parse a string block size specification. This is approximately a
 * subset of the block size specs supported by GNU fileutils:
 *  "nk" = n kilobytes
 *  "nM" = n megabytes
 *  "nG" = n gigabytes
 * All numbers are decimal, and suffixes refer to powers of two.
 * Case-insensitive.
 */
unsigned long parse_blocksize(const char *bs)
{
    char *suf;
    unsigned long r = strtoul(bs, &suf, 10);
    if (*suf != '\0') {
	while (*suf && isspace((unsigned char)*suf)) suf++;
	switch (*suf) {
	  case 'k': case 'K':
	    r *= 1024ul;
	    break;
	  case 'm': case 'M':
	    r *= 1024ul * 1024ul;
	    break;
	  case 'g': case 'G':
	    r *= 1024ul * 1024ul * 1024ul;
	    break;
	  case '\0':
	  default:
	    break;
	}
    }
    return r;
}

/*
 * Parse a ^C style character specification.
 * Returns NULL in `next' if we didn't recognise it as a control character,
 * in which case `c' should be ignored.
 * The precise current parsing is an oddity inherited from the terminal
 * answerback-string parsing code. All sequences start with ^; all except
 * ^<123> are two characters. The ones that are worth keeping are probably:
 *   ^?		    127
 *   ^@A-Z[\]^_	    0-31
 *   a-z	    1-26
 *   <num>	    specified by number (decimal, 0octal, 0xHEX)
 *   ~		    ^ escape
 */
char ctrlparse(char *s, char **next)
{
    char c = 0;
    if (*s != '^') {
	*next = NULL;
    } else {
	s++;
	if (*s == '\0') {
	    *next = NULL;
	} else if (*s == '<') {
	    s++;
	    c = (char)strtol(s, next, 0);
	    if ((*next == s) || (**next != '>')) {
		c = 0;
		*next = NULL;
	    } else
		(*next)++;
	} else if (*s >= 'a' && *s <= 'z') {
	    c = (*s - ('a' - 1));
	    *next = s+1;
	} else if ((*s >= '@' && *s <= '_') || *s == '?' || (*s & 0x80)) {
	    c = ('@' ^ *s);
	    *next = s+1;
	} else if (*s == '~') {
	    c = '^';
	    *next = s+1;
	}
    }
    return c;
}

prompts_t *new_prompts(void *frontend)
{
    prompts_t *p = snew(prompts_t);
    p->prompts = NULL;
    p->n_prompts = 0;
    p->frontend = frontend;
    p->data = NULL;
    p->to_server = TRUE; /* to be on the safe side */
    p->name = p->instruction = NULL;
    p->name_reqd = p->instr_reqd = FALSE;
    return p;
}
void add_prompt(prompts_t *p, char *promptstr, int echo)
{
    prompt_t *pr = snew(prompt_t);
    pr->prompt = promptstr;
    pr->echo = echo;
    pr->result = NULL;
    pr->resultsize = 0;
    p->n_prompts++;
    p->prompts = sresize(p->prompts, p->n_prompts, prompt_t *);
    p->prompts[p->n_prompts-1] = pr;
}
void prompt_ensure_result_size(prompt_t *pr, int newlen)
{
    if ((int)pr->resultsize < newlen) {
        char *newbuf;
        newlen = newlen * 5 / 4 + 512; /* avoid too many small allocs */

        /*
         * We don't use sresize / realloc here, because we will be
         * storing sensitive stuff like passwords in here, and we want
         * to make sure that the data doesn't get copied around in
         * memory without the old copy being destroyed.
         */
        newbuf = snewn(newlen, char);
        memcpy(newbuf, pr->result, pr->resultsize);
        memset(pr->result, '\0', pr->resultsize);
        sfree(pr->result);
        pr->result = newbuf;
        pr->resultsize = newlen;
    }
}
void prompt_set_result(prompt_t *pr, const char *newstr)
{
    prompt_ensure_result_size(pr, strlen(newstr) + 1);
    strcpy(pr->result, newstr);
}
void free_prompts(prompts_t *p)
{
    size_t i;
    for (i=0; i < p->n_prompts; i++) {
	prompt_t *pr = p->prompts[i];
	memset(pr->result, 0, pr->resultsize); /* burn the evidence */
	sfree(pr->result);
	sfree(pr->prompt);
	sfree(pr);
    }
    sfree(p->prompts);
    sfree(p->name);
    sfree(p->instruction);
    sfree(p);
}

/* ----------------------------------------------------------------------
 * String handling routines.
 */

char *dupstr(const char *s)
{
    char *p = NULL;
    if (s) {
        int len = strlen(s);
        p = snewn(len + 1, char);
        strcpy(p, s);
    }
    return p;
}

/* Allocate the concatenation of N strings. Terminate arg list with NULL. */
char *dupcat(const char *s1, ...)
{
    int len;
    char *p, *q, *sn;
    va_list ap;

    len = strlen(s1);
    va_start(ap, s1);
    while (1) {
	sn = va_arg(ap, char *);
	if (!sn)
	    break;
	len += strlen(sn);
    }
    va_end(ap);

    p = snewn(len + 1, char);
    strcpy(p, s1);
    q = p + strlen(p);

    va_start(ap, s1);
    while (1) {
	sn = va_arg(ap, char *);
	if (!sn)
	    break;
	strcpy(q, sn);
	q += strlen(q);
    }
    va_end(ap);

    return p;
}

void burnstr(char *string)             /* sfree(str), only clear it first */
{
    if (string) {
        memset(string, 0, strlen(string));
        sfree(string);
    }
}

/*
 * Do an sprintf(), but into a custom-allocated buffer.
 * 
 * Currently I'm doing this via vsnprintf. This has worked so far,
 * but it's not good, because vsnprintf is not available on all
 * platforms. There's an ifdef to use `_vsnprintf', which seems
 * to be the local name for it on Windows. Other platforms may
 * lack it completely, in which case it'll be time to rewrite
 * this function in a totally different way.
 * 
 * The only `properly' portable solution I can think of is to
 * implement my own format string scanner, which figures out an
 * upper bound for the length of each formatting directive,
 * allocates the buffer as it goes along, and calls sprintf() to
 * actually process each directive. If I ever need to actually do
 * this, some caveats:
 * 
 *  - It's very hard to find a reliable upper bound for
 *    floating-point values. %f, in particular, when supplied with
 *    a number near to the upper or lower limit of representable
 *    numbers, could easily take several hundred characters. It's
 *    probably feasible to predict this statically using the
 *    constants in <float.h>, or even to predict it dynamically by
 *    looking at the exponent of the specific float provided, but
 *    it won't be fun.
 * 
 *  - Don't forget to _check_, after calling sprintf, that it's
 *    used at most the amount of space we had available.
 * 
 *  - Fault any formatting directive we don't fully understand. The
 *    aim here is to _guarantee_ that we never overflow the buffer,
 *    because this is a security-critical function. If we see a
 *    directive we don't know about, we should panic and die rather
 *    than run any risk.
 */
char *dupprintf(const char *fmt, ...)
{
    char *ret;
    va_list ap;
    va_start(ap, fmt);
    ret = dupvprintf(fmt, ap);
    va_end(ap);
    return ret;
}
char *dupvprintf(const char *fmt, va_list ap)
{
    char *buf;
    int len, size;

    buf = snewn(512, char);
    size = 512;

    while (1) {
#ifdef _WINDOWS
#define vsnprintf _vsnprintf
#endif
#ifdef va_copy
	/* Use the `va_copy' macro mandated by C99, if present.
	 * XXX some environments may have this as __va_copy() */
	va_list aq;
	va_copy(aq, ap);
	len = vsnprintf(buf, size, fmt, aq);
	va_end(aq);
#else
	/* Ugh. No va_copy macro, so do something nasty.
	 * Technically, you can't reuse a va_list like this: it is left
	 * unspecified whether advancing a va_list pointer modifies its
	 * value or something it points to, so on some platforms calling
	 * vsnprintf twice on the same va_list might fail hideously
	 * (indeed, it has been observed to).
	 * XXX the autoconf manual suggests that using memcpy() will give
	 *     "maximum portability". */
	len = vsnprintf(buf, size, fmt, ap);
#endif
	if (len >= 0 && len < size) {
	    /* This is the C99-specified criterion for snprintf to have
	     * been completely successful. */
	    return buf;
	} else if (len > 0) {
	    /* This is the C99 error condition: the returned length is
	     * the required buffer size not counting the NUL. */
	    size = len + 1;
	} else {
	    /* This is the pre-C99 glibc error condition: <0 means the
	     * buffer wasn't big enough, so we enlarge it a bit and hope. */
	    size += 512;
	}
	buf = sresize(buf, size, char);
    }
}

/*
 * Read an entire line of text from a file. Return a buffer
 * malloced to be as big as necessary (caller must free).
 */
char *fgetline(FILE *fp)
{
    char *ret = snewn(512, char);
    int size = 512, len = 0;
    while (fgets(ret + len, size - len, fp)) {
	len += strlen(ret + len);
	if (ret[len-1] == '\n')
	    break;		       /* got a newline, we're done */
	size = len + 512;
	ret = sresize(ret, size, char);
    }
    if (len == 0) {		       /* first fgets returned NULL */
	sfree(ret);
	return NULL;
    }
    ret[len] = '\0';
    return ret;
}

/* ----------------------------------------------------------------------
 * Base64 encoding routine. This is required in public-key writing
 * but also in HTTP proxy handling, so it's centralised here.
 */

void base64_encode_atom(unsigned char *data, int n, char *out)
{
    static const char base64_chars[] =
	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

    unsigned word;

    word = data[0] << 16;
    if (n > 1)
	word |= data[1] << 8;
    if (n > 2)
	word |= data[2];
    out[0] = base64_chars[(word >> 18) & 0x3F];
    out[1] = base64_chars[(word >> 12) & 0x3F];
    if (n > 1)
	out[2] = base64_chars[(word >> 6) & 0x3F];
    else
	out[2] = '=';
    if (n > 2)
	out[3] = base64_chars[word & 0x3F];
    else
	out[3] = '=';
}

/* ----------------------------------------------------------------------
 * Generic routines to deal with send buffers: a linked list of
 * smallish blocks, with the operations
 * 
 *  - add an arbitrary amount of data to the end of the list
 *  - remove the first N bytes from the list
 *  - return a (pointer,length) pair giving some initial data in
 *    the list, suitable for passing to a send or write system
 *    call
 *  - retrieve a larger amount of initial data from the list
 *  - return the current size of the buffer chain in bytes
 */

#define BUFFER_GRANULE  512

struct bufchain_granule {
    struct bufchain_granule *next;
    int buflen, bufpos;
    char buf[BUFFER_GRANULE];
};

void bufchain_init(bufchain *ch)
{
    ch->head = ch->tail = NULL;
    ch->buffersize = 0;
}

void bufchain_clear(bufchain *ch)
{
    struct bufchain_granule *b;
    while (ch->head) {
	b = ch->head;
	ch->head = ch->head->next;
	sfree(b);
    }
    ch->tail = NULL;
    ch->buffersize = 0;
}

int bufchain_size(bufchain *ch)
{
    return ch->buffersize;
}

void bufchain_add(bufchain *ch, const void *data, int len)
{
    const char *buf = (const char *)data;

    if (len == 0) return;

    ch->buffersize += len;

    if (ch->tail && ch->tail->buflen < BUFFER_GRANULE) {
	int copylen = min(len, BUFFER_GRANULE - ch->tail->buflen);
	memcpy(ch->tail->buf + ch->tail->buflen, buf, copylen);
	buf += copylen;
	len -= copylen;
	ch->tail->buflen += copylen;
    }
    while (len > 0) {
	int grainlen = min(len, BUFFER_GRANULE);
	struct bufchain_granule *newbuf;
	newbuf = snew(struct bufchain_granule);
	newbuf->bufpos = 0;
	newbuf->buflen = grainlen;
	memcpy(newbuf->buf, buf, grainlen);
	buf += grainlen;
	len -= grainlen;
	if (ch->tail)
	    ch->tail->next = newbuf;
	else
	    ch->head = ch->tail = newbuf;
	newbuf->next = NULL;
	ch->tail = newbuf;
    }
}

void bufchain_consume(bufchain *ch, int len)
{
    struct bufchain_granule *tmp;

    assert(ch->buffersize >= len);
    while (len > 0) {
	int remlen = len;
	assert(ch->head != NULL);
	if (remlen >= ch->head->buflen - ch->head->bufpos) {
	    remlen = ch->head->buflen - ch->head->bufpos;
	    tmp = ch->head;
	    ch->head = tmp->next;
	    sfree(tmp);
	    if (!ch->head)
		ch->tail = NULL;
	} else
	    ch->head->bufpos += remlen;
	ch->buffersize -= remlen;
	len -= remlen;
    }
}

void bufchain_prefix(bufchain *ch, void **data, int *len)
{
    *len = ch->head->buflen - ch->head->bufpos;
    *data = ch->head->buf + ch->head->bufpos;
}

void bufchain_fetch(bufchain *ch, void *data, int len)
{
    struct bufchain_granule *tmp;
    char *data_c = (char *)data;

    tmp = ch->head;

    assert(ch->buffersize >= len);
    while (len > 0) {
	int remlen = len;

	assert(tmp != NULL);
	if (remlen >= tmp->buflen - tmp->bufpos)
	    remlen = tmp->buflen - tmp->bufpos;
	memcpy(data_c, tmp->buf + tmp->bufpos, remlen);

	tmp = tmp->next;
	len -= remlen;
	data_c += remlen;
    }
}

/* ----------------------------------------------------------------------
 * My own versions of malloc, realloc and free. Because I want
 * malloc and realloc to bomb out and exit the program if they run
 * out of memory, realloc to reliably call malloc if passed a NULL
 * pointer, and free to reliably do nothing if passed a NULL
 * pointer. We can also put trace printouts in, if we need to; and
 * we can also replace the allocator with an ElectricFence-like
 * one.
 */

#ifdef MINEFIELD
void *minefield_c_malloc(size_t size);
void minefield_c_free(void *p);
void *minefield_c_realloc(void *p, size_t size);
#endif

#ifdef MALLOC_LOG
static FILE *fp = NULL;

static char *mlog_file = NULL;
static int mlog_line = 0;

void mlog(char *file, int line)
{
    mlog_file = file;
    mlog_line = line;
    if (!fp) {
	fp = fopen("putty_mem.log", "w");
	setvbuf(fp, NULL, _IONBF, BUFSIZ);
    }
    if (fp)
	fprintf(fp, "%s:%d: ", file, line);
}
#endif

void *safemalloc(size_t n, size_t size)
{
    void *p;

    if (n > INT_MAX / size) {
	p = NULL;
    } else {
	size *= n;
	if (size == 0) size = 1;
#ifdef MINEFIELD
	p = minefield_c_malloc(size);
#else
	p = malloc(size);
#endif
    }

    if (!p) {
	char str[200];
#ifdef MALLOC_LOG
	sprintf(str, "Out of memory! (%s:%d, size=%d)",
		mlog_file, mlog_line, size);
	fprintf(fp, "*** %s\n", str);
	fclose(fp);
#else
	strcpy(str, "Out of memory!");
#endif
	modalfatalbox(str);
    }
#ifdef MALLOC_LOG
    if (fp)
	fprintf(fp, "malloc(%d) returns %p\n", size, p);
#endif
    return p;
}

void *saferealloc(void *ptr, size_t n, size_t size)
{
    void *p;

    if (n > INT_MAX / size) {
	p = NULL;
    } else {
	size *= n;
	if (!ptr) {
#ifdef MINEFIELD
	    p = minefield_c_malloc(size);
#else
	    p = malloc(size);
#endif
	} else {
#ifdef MINEFIELD
	    p = minefield_c_realloc(ptr, size);
#else
	    p = realloc(ptr, size);
#endif
	}
    }

    if (!p) {
	char str[200];
#ifdef MALLOC_LOG
	sprintf(str, "Out of memory! (%s:%d, size=%d)",
		mlog_file, mlog_line, size);
	fprintf(fp, "*** %s\n", str);
	fclose(fp);
#else
	strcpy(str, "Out of memory!");
#endif
	modalfatalbox(str);
    }
#ifdef MALLOC_LOG
    if (fp)
	fprintf(fp, "realloc(%p,%d) returns %p\n", ptr, size, p);
#endif
    return p;
}

void safefree(void *ptr)
{
    if (ptr) {
#ifdef MALLOC_LOG
	if (fp)
	    fprintf(fp, "free(%p)\n", ptr);
#endif
#ifdef MINEFIELD
	minefield_c_free(ptr);
#else
	free(ptr);
#endif
    }
#ifdef MALLOC_LOG
    else if (fp)
	fprintf(fp, "freeing null pointer - no action taken\n");
#endif
}

/* ----------------------------------------------------------------------
 * Debugging routines.
 */

#ifdef DEBUG
extern void dputs(char *);             /* defined in per-platform *misc.c */

void debug_printf(char *fmt, ...)
{
    char *buf;
    va_list ap;

    va_start(ap, fmt);
    buf = dupvprintf(fmt, ap);
    dputs(buf);
    sfree(buf);
    va_end(ap);
}


void debug_memdump(void *buf, int len, int L)
{
    int i;
    unsigned char *p = buf;
    char foo[17];
    if (L) {
	int delta;
	debug_printf("\t%d (0x%x) bytes:\n", len, len);
	delta = 15 & (unsigned long int) p;
	p -= delta;
	len += delta;
    }
    for (; 0 < len; p += 16, len -= 16) {
	dputs("  ");
	if (L)
	    debug_printf("%p: ", p);
	strcpy(foo, "................");	/* sixteen dots */
	for (i = 0; i < 16 && i < len; ++i) {
	    if (&p[i] < (unsigned char *) buf) {
		dputs("   ");	       /* 3 spaces */
		foo[i] = ' ';
	    } else {
		debug_printf("%c%02.2x",
			&p[i] != (unsigned char *) buf
			&& i % 4 ? '.' : ' ', p[i]
		    );
		if (p[i] >= ' ' && p[i] <= '~')
		    foo[i] = (char) p[i];
	    }
	}
	foo[i] = '\0';
	debug_printf("%*s%s\n", (16 - i) * 3 + 2, "", foo);
    }
}

#endif				/* def DEBUG */

/*
 * Determine whether or not a Conf represents a session which can
 * sensibly be launched right now.
 */
int conf_launchable(Conf *conf)
{
    if (conf_get_int(conf, CONF_protocol) == PROT_SERIAL)
	return conf_get_str(conf, CONF_serline)[0] != 0;
    else
	return conf_get_str(conf, CONF_host)[0] != 0;
}

char const *conf_dest(Conf *conf)
{
    if (conf_get_int(conf, CONF_protocol) == PROT_SERIAL)
	return conf_get_str(conf, CONF_serline);
    else
	return conf_get_str(conf, CONF_host);
}