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Nick Mathewson
ba05324242
This function decodes something different from the usual c-escaped format. It is only used in controller authorization.
91 lines
2.4 KiB
C
91 lines
2.4 KiB
C
/* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
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* Copyright (c) 2007-2019, The Tor Project, Inc. */
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/* See LICENSE for licensing information */
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/**
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* \file qstring.c
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* \brief Implement QuotedString parsing.
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*
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* Note that this is only used for controller authentication; do not
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* create new users for this. Instead, prefer the cstring.c functions.
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**/
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#include "orconfig.h"
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#include "lib/encoding/qstring.h"
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#include "lib/malloc/malloc.h"
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#include "lib/log/util_bug.h"
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/** If the first <b>in_len_max</b> characters in <b>start</b> contain a
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* QuotedString, return the length of that
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* string (as encoded, including quotes). Otherwise return -1. */
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static inline int
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get_qstring_length(const char *start, size_t in_len_max,
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int *chars_out)
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{
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const char *cp, *end;
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int chars = 0;
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if (*start != '\"')
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return -1;
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cp = start+1;
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end = start+in_len_max;
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/* Calculate length. */
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while (1) {
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if (cp >= end) {
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return -1; /* Too long. */
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} else if (*cp == '\\') {
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if (++cp == end)
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return -1; /* Can't escape EOS. */
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++cp;
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++chars;
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} else if (*cp == '\"') {
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break;
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} else {
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++cp;
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++chars;
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}
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}
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if (chars_out)
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*chars_out = chars;
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return (int)(cp - start+1);
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}
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/** Given a pointer to a string starting at <b>start</b> containing
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* <b>in_len_max</b> characters, decode a string beginning with one double
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* quote, containing any number of non-quote characters or characters escaped
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* with a backslash, and ending with a final double quote. Place the resulting
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* string (unquoted, unescaped) into a newly allocated string in *<b>out</b>;
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* store its length in <b>out_len</b>. On success, return a pointer to the
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* character immediately following the escaped string. On failure, return
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* NULL. */
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const char *
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decode_qstring(const char *start, size_t in_len_max,
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char **out, size_t *out_len)
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{
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const char *cp, *end;
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char *outp;
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int len, n_chars = 0;
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len = get_qstring_length(start, in_len_max, &n_chars);
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if (len<0)
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return NULL;
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end = start+len-1; /* Index of last quote. */
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tor_assert(*end == '\"');
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outp = *out = tor_malloc(len+1);
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*out_len = n_chars;
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cp = start+1;
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while (cp < end) {
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if (*cp == '\\')
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++cp;
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*outp++ = *cp++;
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}
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*outp = '\0';
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tor_assert((outp - *out) == (int)*out_len);
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return end+1;
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}
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