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Diffstat (limited to 'src/regex/regex_random.c')
| -rw-r--r-- | src/regex/regex_random.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/src/regex/regex_random.c b/src/regex/regex_random.c new file mode 100644 index 0000000..eee0c73 --- /dev/null +++ b/src/regex/regex_random.c @@ -0,0 +1,170 @@ +/* + This file is part of GNUnet + (C) 2012 Christian Grothoff (and other contributing authors) + + GNUnet is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published + by the Free Software Foundation; either version 3, or (at your + option) any later version. + + GNUnet is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU General Public License + along with GNUnet; see the file COPYING. If not, write to the + Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. +*/ +/** + * @file src/regex/regex_random.c + * @brief functions for creating random regular expressions and strings + * @author Maximilian Szengel + */ +#include "platform.h" +#include "gnunet_regex_lib.h" +#include "gnunet_crypto_lib.h" +#include "regex_internal.h" + + +/** + * Get a (pseudo) random valid literal for building a regular expression. + * + * @return random valid literal + */ +char +get_random_literal () +{ + uint32_t ridx; + + ridx = + GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, + (uint32_t) strlen (ALLOWED_LITERALS)); + + return ALLOWED_LITERALS[ridx]; +} + + +/** + * Generate a (pseudo) random regular expression of length 'rx_length', as well + * as a (optional) string that will be matched by the generated regex. The + * returned regex needs to be freed. + * + * @param rx_length length of the random regex. + * @param matching_str (optional) pointer to a string that will contain a string + * that will be matched by the generated regex, if + * 'matching_str' pointer was not NULL. Make sure you + * allocated at least rx_length+1 bytes for this sting. + * + * @return NULL if 'rx_length' is 0, a random regex of length 'rx_length', which + * needs to be freed, otherwise. + */ +char * +GNUNET_REGEX_generate_random_regex (size_t rx_length, char *matching_str) +{ + char *rx; + char *rx_p; + char *matching_strp; + unsigned int i; + unsigned int char_op_switch; + unsigned int last_was_op; + int rx_op; + char current_char; + + if (0 == rx_length) + return NULL; + + if (NULL != matching_str) + matching_strp = matching_str; + else + matching_strp = NULL; + + rx = GNUNET_malloc (rx_length + 1); + rx_p = rx; + current_char = 0; + last_was_op = 1; + + for (i = 0; i < rx_length; i++) + { + char_op_switch = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, 2); + + if (0 == char_op_switch && !last_was_op) + { + last_was_op = 1; + rx_op = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, 4); + + switch (rx_op) + { + case 0: + current_char = '+'; + break; + case 1: + current_char = '*'; + break; + case 2: + current_char = '?'; + break; + case 3: + if (i < rx_length - 1) /* '|' cannot be at the end */ + current_char = '|'; + else + current_char = get_random_literal (); + break; + } + } + else + { + current_char = get_random_literal (); + last_was_op = 0; + } + + if (NULL != matching_strp && + (current_char != '+' && current_char != '*' && current_char != '?' && + current_char != '|')) + { + *matching_strp = current_char; + matching_strp++; + } + + *rx_p = current_char; + rx_p++; + } + *rx_p = '\0'; + if (NULL != matching_strp) + *matching_strp = '\0'; + + return rx; +} + +/** + * Generate a random string of maximum length 'max_len' that only contains literals allowed + * in a regular expression. The string might be 0 chars long but is garantueed + * to be shorter or equal to 'max_len'. + * + * @param max_len maximum length of the string that should be generated. + * + * @return random string that needs to be freed. + */ +char * +GNUNET_REGEX_generate_random_string (size_t max_len) +{ + unsigned int i; + char *str; + size_t len; + + if (1 > max_len) + return GNUNET_strdup (""); + + len = (size_t) GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, max_len); + str = GNUNET_malloc (len + 1); + + for (i = 0; i < len; i++) + { + str[i] = get_random_literal (); + } + + str[i] = '\0'; + + return str; +} |