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/* Copyright (c) 2001 Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2019, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file cstring.c
*
* \brief Decode data that has been written as a C literal.
**/
#include "lib/encoding/cstring.h"
#include "lib/log/log.h"
#include "lib/log/util_bug.h"
#include "lib/malloc/malloc.h"
#include "lib/string/compat_ctype.h"
#include <string.h>
#define TOR_ISODIGIT(c) ('0' <= (c) && (c) <= '7')
/** Given a c-style double-quoted escaped string in <b>s</b>, extract and
* decode its contents into a newly allocated string. On success, assign this
* string to *<b>result</b>, assign its length to <b>size_out</b> (if
* provided), and return a pointer to the position in <b>s</b> immediately
* after the string. On failure, return NULL.
*/
const char *
unescape_string(const char *s, char **result, size_t *size_out)
{
const char *cp;
char *out;
if (s[0] != '\"')
return NULL;
cp = s+1;
while (1) {
switch (*cp) {
case '\0':
case '\n':
return NULL;
case '\"':
goto end_of_loop;
case '\\':
if (cp[1] == 'x' || cp[1] == 'X') {
if (!(TOR_ISXDIGIT(cp[2]) && TOR_ISXDIGIT(cp[3])))
return NULL;
cp += 4;
} else if (TOR_ISODIGIT(cp[1])) {
cp += 2;
if (TOR_ISODIGIT(*cp)) ++cp;
if (TOR_ISODIGIT(*cp)) ++cp;
} else if (cp[1] == 'n' || cp[1] == 'r' || cp[1] == 't' || cp[1] == '"'
|| cp[1] == '\\' || cp[1] == '\'') {
cp += 2;
} else {
return NULL;
}
break;
default:
++cp;
break;
}
}
end_of_loop:
out = *result = tor_malloc(cp-s + 1);
cp = s+1;
while (1) {
switch (*cp)
{
case '\"':
*out = '\0';
if (size_out) *size_out = out - *result;
return cp+1;
/* LCOV_EXCL_START -- we caught this in parse_config_from_line. */
case '\0':
tor_fragile_assert();
tor_free(*result);
return NULL;
/* LCOV_EXCL_STOP */
case '\\':
switch (cp[1])
{
case 'n': *out++ = '\n'; cp += 2; break;
case 'r': *out++ = '\r'; cp += 2; break;
case 't': *out++ = '\t'; cp += 2; break;
case 'x': case 'X':
{
int x1, x2;
x1 = hex_decode_digit(cp[2]);
x2 = hex_decode_digit(cp[3]);
if (x1 == -1 || x2 == -1) {
/* LCOV_EXCL_START */
/* we caught this above in the initial loop. */
tor_assert_nonfatal_unreached();
tor_free(*result);
return NULL;
/* LCOV_EXCL_STOP */
}
*out++ = ((x1<<4) + x2);
cp += 4;
}
break;
case '0': case '1': case '2': case '3': case '4': case '5':
case '6': case '7':
{
int n = cp[1]-'0';
cp += 2;
if (TOR_ISODIGIT(*cp)) { n = n*8 + *cp-'0'; cp++; }
if (TOR_ISODIGIT(*cp)) { n = n*8 + *cp-'0'; cp++; }
if (n > 255) { tor_free(*result); return NULL; }
*out++ = (char)n;
}
break;
case '\'':
case '\"':
case '\\':
case '\?':
*out++ = cp[1];
cp += 2;
break;
/* LCOV_EXCL_START */
default:
/* we caught this above in the initial loop. */
tor_assert_nonfatal_unreached();
tor_free(*result); return NULL;
/* LCOV_EXCL_STOP */
}
break;
default:
*out++ = *cp++;
}
}
}
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