/src/tor/src/lib/encoding/cstring.c

Source
/* Copyright (c) 2001 Matej Pfajfar.
 * Copyright (c) 2001-2004, Roger Dingledine.
 * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
 * Copyright (c) 2007-2021, 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++;
      }
  }
}

Line	Count	Source
1		/* Copyright (c) 2001 Matej Pfajfar.
2		* Copyright (c) 2001-2004, Roger Dingledine.
3		* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
4		* Copyright (c) 2007-2021, The Tor Project, Inc. */
5		/* See LICENSE for licensing information */
6
7		/**
8		* \file cstring.c
9		*
10		* \brief Decode data that has been written as a C literal.
11		**/
12
13		#include "lib/encoding/cstring.h"
14		#include "lib/log/log.h"
15		#include "lib/log/util_bug.h"
16		#include "lib/malloc/malloc.h"
17		#include "lib/string/compat_ctype.h"
18
19		#include <string.h>
20
21	52.4M	#define TOR_ISODIGIT(c) ('0' <= (c) && (c) <= '7')
22
23		/** Given a c-style double-quoted escaped string in <b>s</b>, extract and
24		* decode its contents into a newly allocated string. On success, assign this
25		* string to *<b>result</b>, assign its length to <b>size_out</b> (if
26		* provided), and return a pointer to the position in <b>s</b> immediately
27		* after the string. On failure, return NULL.
28		*/
29		const char *
30		unescape_string(const char s, char result, size_t size_out)
31	5.24M	{
32	5.24M	const char *cp;
33	5.24M	char *out;
34	5.24M	if (s[0] != '\"')
35	1	return NULL;
36	5.24M	cp = s+1;
37	19.7M	while (1) {
38	19.7M	switch (*cp) {
39	33	case '\0':
40	34	case '\n':
41	34	return NULL;
42	5.24M	case '\"':
43	5.24M	goto end_of_loop;
44	10.4M	case '\\':
45	10.4M	if (cp[1] == 'x' \|\| cp[1] == 'X') {
46	7.54k	if (!(TOR_ISXDIGIT(cp[2]) && TOR_ISXDIGIT(cp[3])))
47	17	return NULL;
48	7.52k	cp += 4;
49	10.4M	} else if (TOR_ISODIGIT(cp[1])) {
50	10.4M	cp += 2;
51	10.4M	if (TOR_ISODIGIT(*cp)) ++cp;
52	10.4M	if (TOR_ISODIGIT(*cp)) ++cp;
53	10.4M	} else if (cp[1] == 'n' \|\| cp[1] == 'r' \|\| cp[1] == 't' \|\| cp[1] == '"'
54	1.57k	\|\| cp[1] == '\\' \|\| cp[1] == '\'') {
55	1.57k	cp += 2;
56	1.57k	} else {
57	41	return NULL;
58	41	}
59	10.4M	break;
60	10.4M	default:
61	3.96M	++cp;
62	3.96M	break;
63	19.7M	}
64	19.7M	}
65	5.24M	end_of_loop:
66	5.24M	out = *result = tor_malloc(cp-s + 1);
67	5.24M	cp = s+1;
68	18.6M	while (1) {
69	18.6M	switch (*cp)
70	18.6M	{
71	5.24M	case '\"':
72	5.24M	*out = '\0';
73	5.24M	if (size_out) size_out = out - result;
74	5.24M	return cp+1;
75
76		/* LCOV_EXCL_START -- we caught this in parse_config_from_line. */
77	0	case '\0':
78	0	tor_fragile_assert();
79	0	tor_free(*result);
80	0	return NULL;
81		/* LCOV_EXCL_STOP */
82	10.4M	case '\\':
83	10.4M	switch (cp[1])
84	10.4M	{
85	194	case 'n': *out++ = '\n'; cp += 2; break;
86	261	case 'r': *out++ = '\r'; cp += 2; break;
87	258	case 't': *out++ = '\t'; cp += 2; break;
88	6.96k	case 'x': case 'X':
89	6.96k	{
90	6.96k	int x1, x2;
91
92	6.96k	x1 = hex_decode_digit(cp[2]);
93	6.96k	x2 = hex_decode_digit(cp[3]);
94	6.96k	if (x1 == -1 \|\| x2 == -1) {
95		/* LCOV_EXCL_START */
96		/* we caught this above in the initial loop. */
97	0	tor_assert_nonfatal_unreached();
98	0	tor_free(*result);
99	0	return NULL;
100		/* LCOV_EXCL_STOP */
101	0	}
102
103	6.96k	*out++ = ((x1<<4) + x2);
104	6.96k	cp += 4;
105	6.96k	}
106	0	break;
107	10.4M	case '0': case '1': case '2': case '3': case '4': case '5':
108	10.4M	case '6': case '7':
109	10.4M	{
110	10.4M	int n = cp[1]-'0';
111	10.4M	cp += 2;
112	10.4M	if (TOR_ISODIGIT(cp)) { n = n8 + *cp-'0'; cp++; }
113	10.4M	if (TOR_ISODIGIT(cp)) { n = n8 + *cp-'0'; cp++; }
114	10.4M	if (n > 255) { tor_free(*result); return NULL; }
115	10.4M	*out++ = (char)n;
116	10.4M	}
117	0	break;
118	323	case '\'':
119	588	case '\"':
120	860	case '\\':
121	860	case '\?':
122	860	*out++ = cp[1];
123	860	cp += 2;
124	860	break;
125
126		/* LCOV_EXCL_START */
127	0	default:
128		/* we caught this above in the initial loop. */
129	0	tor_assert_nonfatal_unreached();
130	0	tor_free(*result); return NULL;
131		/* LCOV_EXCL_STOP */
132	10.4M	}
133	10.4M	break;
134	10.4M	default:
135	2.91M	out++ = cp++;
136	18.6M	}
137	18.6M	}
138	5.24M	}

Coverage Report

Created: 2025-11-17 06:37