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putty/misc.c

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18 KiB
C
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/*
* 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);
smemclr(pr->result, 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];
smemclr(pr->result, 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) {
smemclr(string, 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_MIN_GRANULE 512
struct bufchain_granule {
struct bufchain_granule *next;
char *bufpos, *bufend, *bufmax;
};
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;
while (len > 0) {
if (ch->tail && ch->tail->bufend < ch->tail->bufmax) {
int copylen = min(len, ch->tail->bufmax - ch->tail->bufend);
memcpy(ch->tail->bufend, buf, copylen);
buf += copylen;
len -= copylen;
ch->tail->bufend += copylen;
}
if (len > 0) {
int grainlen =
max(sizeof(struct bufchain_granule) + len, BUFFER_MIN_GRANULE);
struct bufchain_granule *newbuf;
newbuf = smalloc(grainlen);
newbuf->bufpos = newbuf->bufend =
(char *)newbuf + sizeof(struct bufchain_granule);
newbuf->bufmax = (char *)newbuf + grainlen;
newbuf->next = NULL;
if (ch->tail)
ch->tail->next = newbuf;
else
ch->head = newbuf;
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->bufend - ch->head->bufpos) {
remlen = ch->head->bufend - ch->head->bufpos;
tmp = ch->head;
ch->head = tmp->next;
if (!ch->head)
ch->tail = NULL;
sfree(tmp);
} else
ch->head->bufpos += remlen;
ch->buffersize -= remlen;
len -= remlen;
}
}
void bufchain_prefix(bufchain *ch, void **data, int *len)
{
*len = ch->head->bufend - ch->head->bufpos;
*data = 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->bufend - tmp->bufpos)
remlen = tmp->bufend - tmp->bufpos;
memcpy(data_c, 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);
}
#ifndef PLATFORM_HAS_SMEMCLR
/*
* Securely wipe memory.
*
* The actual wiping is no different from what memset would do: the
* point of 'securely' is to try to be sure over-clever compilers
* won't optimise away memsets on variables that are about to be freed
* or go out of scope. See
* https://buildsecurityin.us-cert.gov/bsi-rules/home/g1/771-BSI.html
*
* Some platforms (e.g. Windows) may provide their own version of this
* function.
*/
void smemclr(void *b, size_t n) {
volatile char *vp;
if (b && n > 0) {
/*
* Zero out the memory.
*/
memset(b, 0, n);
/*
* Perform a volatile access to the object, forcing the
* compiler to admit that the previous memset was important.
*
* This while loop should in practice run for zero iterations
* (since we know we just zeroed the object out), but in
* theory (as far as the compiler knows) it might range over
* the whole object. (If we had just written, say, '*vp =
* *vp;', a compiler could in principle have 'helpfully'
* optimised the memset into only zeroing out the first byte.
* This should be robust.)
*/
vp = b;
while (*vp) vp++;
}
}
#endif
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