/src/freeradius-server/src/lib/util/regex.c

Source
/*
 *   This program 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 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program 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 this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */

/** Wrappers around various regular expression libraries
 *
 * @file src/lib/util/regex.c
 *
 * @copyright 2014 The FreeRADIUS server project
 * @copyright 2014 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
RCSID("$Id: ecec9010400c9be79a070b6c6380a57e34b0e64e $")

#ifdef HAVE_REGEX

#include <freeradius-devel/util/regex.h>
#include <freeradius-devel/util/atexit.h>

#if defined(HAVE_REGEX_PCRE2) && defined(PCRE2_CONFIG_JIT)
#ifndef FR_PCRE_JIT_STACK_MIN
#  define FR_PCRE_JIT_STACK_MIN (128 * 1024)
#endif
#ifndef FR_PCRE_JIT_STACK_MAX
#  define FR_PCRE_JIT_STACK_MAX (512 * 1024)
#endif
#endif

const fr_sbuff_escape_rules_t regex_escape_rules = {
  .name = "regex",
  .chr = '\\',
  .subs = {
    ['$'] = '$',
    ['('] = '(',
    ['*'] = '*',
    ['+'] = '+',
    ['.'] = '.',
    ['/'] = '/',
    ['?'] = '?',
    ['['] = '[',
    ['\\'] = '\\',
    ['^'] = '^',
    ['`'] = '`',
    ['|'] = '|',
    ['\a'] = 'a',
    ['\b'] = 'b',
    ['\n'] = 'n',
    ['\r'] = 'r',
    ['\t'] = 't',
    ['\v'] = 'v'
  },
  .esc = {
    SBUFF_CHAR_UNPRINTABLES_LOW,
    SBUFF_CHAR_UNPRINTABLES_EXTENDED
  },
  .do_utf8 = true,
  .do_oct = true
};


/*
 *######################################
 *#      FUNCTIONS FOR LIBPCRE2        #
 *######################################
 */
#ifdef HAVE_REGEX_PCRE2
/*
 *  Wrapper functions for libpcre2. Much more powerful, and guaranteed
 *  to be binary safe for both patterns and subjects but require
 *  libpcre2.
 */

/** Thread local storage for PCRE2
 *
 * Not all this storage is thread local, but it simplifies cleanup if
 * we bind its lifetime to the thread, and lets us get away with not
 * having specific init/free functions.
 */
typedef struct {
  TALLOC_CTX    *alloc_ctx; //!< Context used for any allocations.
  pcre2_general_context *gcontext;  //!< General context.
  pcre2_compile_context *ccontext;  //!< Compile context.
  pcre2_match_context *mcontext;  //!< Match context.
#ifdef PCRE2_CONFIG_JIT
  pcre2_jit_stack   *jit_stack; //!< Jit stack for executing jit'd patterns.
  bool      do_jit;   //!< Whether we have runtime JIT support.
#endif
} fr_pcre2_tls_t;

/** Thread local storage for pcre2
 *
 */
static _Thread_local fr_pcre2_tls_t *fr_pcre2_tls;

/** Talloc wrapper for pcre2 memory allocation
 *
 * @param[in] to_alloc    How many bytes to alloc.
 * @param[in] uctx    UNUSED.
 */
static void *_pcre2_talloc(PCRE2_SIZE to_alloc, UNUSED void *uctx)
{
  return talloc_array(fr_pcre2_tls->alloc_ctx, uint8_t, to_alloc);
}

/** Talloc wrapper for pcre2 memory freeing
 *
 * @param[in] to_free   Memory to free.
 * @param[in] uctx    UNUSED.
 */
static void _pcre2_talloc_free(void *to_free, UNUSED void *uctx)
{
  talloc_free(to_free);
}

/** Free thread local data
 *
 * @param[in] tls Thread local data to free.
 */
static int _pcre2_tls_free(fr_pcre2_tls_t *tls)
{
  if (tls->gcontext) pcre2_general_context_free(tls->gcontext);
  if (tls->ccontext) pcre2_compile_context_free(tls->ccontext);
  if (tls->mcontext) pcre2_match_context_free(tls->mcontext);
#ifdef PCRE2_CONFIG_JIT
  if (tls->jit_stack) pcre2_jit_stack_free(tls->jit_stack);
#endif

  return 0;
}

static int _pcre2_tls_free_on_exit(void *arg)
{
  return talloc_free(arg);
}

/** Thread local init for pcre2
 *
 */
static int fr_pcre2_tls_init(void)
{
  fr_pcre2_tls_t *tls;

  if (unlikely(fr_pcre2_tls != NULL)) return 0;

  fr_pcre2_tls = tls = talloc_zero(NULL, fr_pcre2_tls_t);
  if (!tls) return -1;
  talloc_set_destructor(tls, _pcre2_tls_free);

  tls->gcontext = pcre2_general_context_create(_pcre2_talloc, _pcre2_talloc_free, NULL);
  if (!tls->gcontext) {
    fr_strerror_const("Failed allocating general context");
    return -1;
  }

  tls->ccontext = pcre2_compile_context_create(tls->gcontext);
  if (!tls->ccontext) {
    fr_strerror_const("Failed allocating compile context");
  error:
    fr_pcre2_tls = NULL;
    _pcre2_tls_free(tls);
    return -1;
  }

  tls->mcontext = pcre2_match_context_create(tls->gcontext);
  if (!tls->mcontext) {
    fr_strerror_const("Failed allocating match context");
    goto error;
  }

#ifdef PCRE2_CONFIG_JIT
  pcre2_config(PCRE2_CONFIG_JIT, &tls->do_jit);
  if (tls->do_jit) {
    tls->jit_stack = pcre2_jit_stack_create(FR_PCRE_JIT_STACK_MIN, FR_PCRE_JIT_STACK_MAX, tls->gcontext);
    if (!tls->jit_stack) {
      fr_strerror_const("Failed allocating JIT stack");
      goto error;
    }
    pcre2_jit_stack_assign(tls->mcontext, NULL, tls->jit_stack);
  }
#endif

  /*
   *  Free on thread exit
   */
  fr_atexit_thread_local(fr_pcre2_tls, _pcre2_tls_free_on_exit, tls);
  fr_pcre2_tls = tls; /* Assign to thread local storage */

  return 0;
}

/** Free regex_t structure
 *
 * Calls libpcre specific free functions for the expression and study.
 *
 * @param preg to free.
 */
static int _regex_free(regex_t *preg)
{
  if (preg->compiled) pcre2_code_free(preg->compiled);

  return 0;
}

/** Wrapper around pcre2_compile
 *
 * Allows the rest of the code to do compilations using one function signature.
 *
 * @note Compiled expression must be freed with talloc_free.
 *
 * @param[out] out    Where to write out a pointer to the structure containing
 *        the compiled expression.
 * @param[in] pattern   to compile.
 * @param[in] len   of pattern.
 * @param[in] flags   controlling matching. May be NULL.
 * @param[in] subcaptures Whether to compile the regular expression to store subcapture
 *        data.
 * @param[in] runtime   If false run the pattern through the PCRE JIT (if available)
 *        to convert it to machine code. This trades startup time (longer)
 *        for runtime performance (better).
 * @return
 *  - >= 1 on success.
 *  - <= 0 on error. Negative value is offset of parse error.
 */
ssize_t regex_compile(TALLOC_CTX *ctx, regex_t **out, char const *pattern, size_t len,
          fr_regex_flags_t const *flags, bool subcaptures, bool runtime)
{
  int   ret;
  PCRE2_SIZE  offset;
  uint32_t  cflags = 0;
  regex_t   *preg;

  /*
   *  Check inputs
   */
  *out = NULL;

  /*
   *  Thread local initialisation
   */
  if (unlikely(!fr_pcre2_tls) && (fr_pcre2_tls_init() < 0)) return -1;

  if (len == 0) {
    fr_strerror_const("Empty expression");
    return 0;
  }

  /*
   *  Options
   */
  if (flags) {
     /* flags->global implemented by substitution function */
    if (flags->ignore_case) cflags |= PCRE2_CASELESS;
    if (flags->multiline) cflags |= PCRE2_MULTILINE;
    if (flags->dot_all) cflags |= PCRE2_DOTALL;
    if (flags->unicode) cflags |= PCRE2_UTF;
    if (flags->extended) cflags |= PCRE2_EXTENDED;
  }

  if (!subcaptures) cflags |= PCRE2_NO_AUTO_CAPTURE;

  preg = talloc_zero(ctx, regex_t);
  talloc_set_destructor(preg, _regex_free);

  preg->compiled = pcre2_compile((PCRE2_SPTR8)pattern, len,
               cflags, &ret, &offset, fr_pcre2_tls->ccontext);
  if (!preg->compiled) {
    PCRE2_UCHAR errbuff[128];

    pcre2_get_error_message(ret, errbuff, sizeof(errbuff));
    fr_strerror_printf("%s", (char *)errbuff);
    talloc_free(preg);

    return -(ssize_t)offset;
  }

  if (!runtime) {
    preg->precompiled = true;

#ifdef PCRE2_CONFIG_JIT
    /*
     *  This is expensive, so only do it for
     *  expressions that are going to be
     *  evaluated repeatedly.
     */
    if (fr_pcre2_tls->do_jit) {
      ret = pcre2_jit_compile(preg->compiled, PCRE2_JIT_COMPLETE);
      if (ret < 0) {
        PCRE2_UCHAR errbuff[128];

        pcre2_get_error_message(ret, errbuff, sizeof(errbuff));
        fr_strerror_printf("Pattern JIT failed: %s", (char *)errbuff);
        talloc_free(preg);

        return 0;
      }
      preg->jitd = true;
    }
#endif
  }

  *out = preg;

  return len;
}

/** Wrapper around pcre2_exec
 *
 * @param[in] preg  The compiled expression.
 * @param[in] subject to match.
 * @param[in] len Length of subject.
 * @param[in] regmatch  Array of match pointers.
 * @return
 *  - -1 on failure.
 *  - 0 on no match.
 *  - 1 on match.
 */
int regex_exec(regex_t *preg, char const *subject, size_t len, fr_regmatch_t *regmatch)
{
  int     ret;
  uint32_t    options = 0;

  char      *our_subject = NULL;
  bool      dup_subject = true;
  pcre2_match_data  *match_data;

  /*
   *  Thread local initialisation
   */
  if (unlikely(!fr_pcre2_tls) && (fr_pcre2_tls_init() < 0)) return -1;

  if (regmatch) {
#ifdef PCRE2_COPY_MATCHED_SUBJECT
    /*
     *  This is apparently only supported for pcre2_match
     *  NOT pcre2_jit_match.
     */
#  ifdef PCRE2_CONFIG_JIT
    if (!preg->jitd) {
#  endif
      dup_subject = false;

      /*
       *  If PCRE2_COPY_MATCHED_SUBJECT is available
       *  and set as an options flag, pcre2_match will
       *  strdup the subject string if pcre2_match is
       *  successful and store a pointer to it in the
       *  regmatch struct.
       *
       *  The lifetime of the string memory will be
       *  bound to the regmatch struct.  This is more
       *  efficient that doing it ourselves, as the
       *  strdup only occurs if the subject matches.
       */
      options |= PCRE2_COPY_MATCHED_SUBJECT;
#  ifdef PCRE2_CONFIG_JIT
    }
#  endif
#endif
    if (dup_subject) {
      /*
       *  We have to dup and operate on the duplicate
       *  of the subject, because pcre2_jit_match and
       *  pcre2_match store a pointer to the subject
       *  in the regmatch structure.
       */
      subject = our_subject = talloc_bstrndup(regmatch, subject, len);
      if (!subject) {
        fr_strerror_const("Out of memory");
        return -1;
      }
#ifndef NDEBUG
      regmatch->subject = subject; /* Stored only for tracking memory issues */
#endif
    }
  }

  /*
   *  If we weren't given match data we
   *  need to alloc it else pcre2_match
   *  fails when passed NULL match data.
   */
  if (!regmatch) {
    match_data = pcre2_match_data_create_from_pattern(preg->compiled, fr_pcre2_tls->gcontext);
    if (!match_data) {
      fr_strerror_const("Failed allocating temporary match data");
      return -1;
    }
  } else {
    match_data = regmatch->match_data;
  }

#ifdef PCRE2_CONFIG_JIT
  if (preg->jitd) {
    ret = pcre2_jit_match(preg->compiled, (PCRE2_SPTR8)subject, len, 0, options,
              match_data, fr_pcre2_tls->mcontext);
  } else
#endif
  {
    ret = pcre2_match(preg->compiled, (PCRE2_SPTR8)subject, len, 0, options,
          match_data, fr_pcre2_tls->mcontext);
  }
  if (!regmatch) pcre2_match_data_free(match_data);
  if (ret < 0) {
    PCRE2_UCHAR errbuff[128];

    if (dup_subject) talloc_free(our_subject);

    if (ret == PCRE2_ERROR_NOMATCH) {
      if (regmatch) regmatch->used = 0;
      return 0;
    }

    pcre2_get_error_message(ret, errbuff, sizeof(errbuff));
    fr_strerror_printf("regex evaluation failed with code (%i): %s", ret, errbuff);

    return -1;
  }

  if (regmatch) regmatch->used = ret;

  return 1;
}

/** Wrapper around pcre2_substitute
 *
 * @param[in] ctx   to allocate output string in.
 * @param[out] out    Output string with replacements performed.
 * @param[in] max_out   Maximum length of output buffer.  If this is 0 then
 *        the output length is unlimited.
 * @param[in] preg    The compiled expression.
 * @param[in] flags   that affect matching.
 * @param[in] subject   to perform replacements on.
 * @param[in] subject_len the length of the subject.
 * @param[in] replacement replacement string containing substitution
 *        markers.
 * @param[in] replacement_len Length of the replacement string.
 * @param[in] regmatch    Array of match pointers.
 * @return
 *  - >= 0 the length of the output string.
 *  - < 0 on error.
 */
int regex_substitute(TALLOC_CTX *ctx, char **out, size_t max_out, regex_t *preg, fr_regex_flags_t const *flags,
         char const *subject, size_t subject_len,
         char const *replacement, size_t replacement_len,
         fr_regmatch_t *regmatch)
{
  int     ret;
  uint32_t    options = 0;
  size_t      buff_len, actual_len;
  char      *buff;

#ifndef PCRE2_COPY_MATCHED_SUBJECT
  char      *our_subject = NULL;
#endif

  /*
   *  Thread local initialisation
   */
  if (unlikely(!fr_pcre2_tls) && (fr_pcre2_tls_init() < 0)) return -1;

  /*
   *  Internally pcre2_substitute just calls pcre2_match to
   *  generate the match data, so the same hack as the
   *  regex_exec function above is required.
   */
  if (regmatch) {
#ifndef PCRE2_COPY_MATCHED_SUBJECT
    /*
     *  We have to dup and operate on the duplicate
     *  of the subject, because pcre2_jit_match and
     *  pcre2_match store a pointer to the subject
     *  in the regmatch structure.
     */
    subject = our_subject = talloc_bstrndup(regmatch, subject, subject_len);
    if (!subject) {
      fr_strerror_const("Out of memory");
      return -1;
    }
#else
    /*
     *  If PCRE2_COPY_MATCHED_SUBJECT is available
     *  and set as an options flag, pcre2_match will
     *  strdup the subject string if pcre2_match is
     *  successful and store a pointer to it in the
     *  regmatch struct.
     *
     *  The lifetime of the string memory will be
     *  bound to the regmatch struct.  This is more
     *  efficient that doing it ourselves, as the
     *  strdup only occurs if the subject matches.
     */
    options |= PCRE2_COPY_MATCHED_SUBJECT;
#endif
  }

  /*
   *  Guess (badly) what the length of the output buffer should be
   */
  actual_len = buff_len = subject_len + 1;  /* +1 for the \0 */
  buff = talloc_array(ctx, char, buff_len);
  if (!buff) {
#ifndef PCRE2_COPY_MATCHED_SUBJECT
    talloc_free(our_subject);
#endif
    fr_strerror_const("Out of memory");
    return -1;
  }

  options |= PCRE2_SUBSTITUTE_OVERFLOW_LENGTH;
  if (flags->global) options |= PCRE2_SUBSTITUTE_GLOBAL;

again:
  /*
   *  actual_len input value should be the size of the
   *  buffer including space for '\0'.
   *  If input buffer is too small, then actual_len will be set
   *      to the buffer space needed including space for '\0'.
   *  If input buffer is the correct size, then actual_len
   *  will be set to the size of the string written to buff
   *  without the terminating '\0'.
   */
  ret = pcre2_substitute(preg->compiled,
             (PCRE2_SPTR8)subject, (PCRE2_SIZE)subject_len, 0,
             options, NULL, fr_pcre2_tls->mcontext,
             (PCRE2_UCHAR const *)replacement, replacement_len, (PCRE2_UCHAR *)buff, &actual_len);

  if (ret < 0) {
    PCRE2_UCHAR errbuff[128];

#ifndef PCRE2_COPY_MATCHED_SUBJECT
    talloc_free(our_subject);
#endif
    talloc_free(buff);

    if (ret == PCRE2_ERROR_NOMEMORY) {
      if ((max_out > 0) && (actual_len > max_out)) {
        fr_strerror_printf("String length with substitutions (%zu) "
                "exceeds max string length (%zu)", actual_len - 1, max_out - 1);
        return -1;
      }

      /*
       *  Check that actual_len != buff_len as that'd be
       *  an actual error.
       */
      if (actual_len == buff_len) {
        fr_strerror_const("libpcre2 out of memory");
        return -1;
      }
      buff_len = actual_len;  /* The length we get passed back includes the \0 */
      buff = talloc_array(ctx, char, buff_len);
      goto again;
    }

    if (ret == PCRE2_ERROR_NOMATCH) {
      if (regmatch) regmatch->used = 0;
      return 0;
    }

    pcre2_get_error_message(ret, errbuff, sizeof(errbuff));
    fr_strerror_printf("regex evaluation failed with code (%i): %s", ret, errbuff);
    return -1;
  }

  /*
   *  Trim the replacement buffer to the correct length
   *
   *  buff_len includes \0.
   *  ...and as pcre2_substitute just succeeded actual_len does not include \0.
   */
  if (actual_len < (buff_len - 1)) {
    buff = talloc_bstr_realloc(ctx, buff, actual_len);
    if (!buff) {
      fr_strerror_const("reallocing pcre2_substitute result buffer failed");
      return -1;
    }
  }

  if (regmatch) regmatch->used = ret;
  *out = buff;

  return 1;
}


/** Returns the number of subcapture groups
 *
 * @return
 *  - >0 The number of subcaptures contained within the pattern
 *  - 0 if the number of subcaptures can't be determined.
 */
uint32_t regex_subcapture_count(regex_t const *preg)
{
  uint32_t count;

  if (pcre2_pattern_info(preg->compiled, PCRE2_INFO_CAPTURECOUNT, &count) != 0) {
    fr_strerror_const("Error determining subcapture group count");
    return 0;
  }

  return count + 1;
}

/** Free libpcre2's matchdata
 *
 * @note Don't call directly, will be called if talloc_free is called on a #regmatch_t.
 */
static int _pcre2_match_data_free(fr_regmatch_t *regmatch)
{
  pcre2_match_data_free(regmatch->match_data);
  return 0;
}

/** Allocate vectors to fill with match data
 *
 * @param[in] ctx to allocate match vectors in.
 * @param[in] count The number of vectors to allocate.
 * @return
 *  - NULL on error.
 *  - Array of match vectors.
 */
fr_regmatch_t *regex_match_data_alloc(TALLOC_CTX *ctx, uint32_t count)
{
  fr_regmatch_t *regmatch;

  /*
   *  Thread local initialisation
   */
  if (unlikely(!fr_pcre2_tls) && (fr_pcre2_tls_init() < 0)) return NULL;

  regmatch = talloc(ctx, fr_regmatch_t);
  if (!regmatch) {
  oom:
    fr_strerror_const("Out of memory");
    return NULL;
  }

  regmatch->match_data = pcre2_match_data_create(count, fr_pcre2_tls->gcontext);
  if (!regmatch->match_data) {
    talloc_free(regmatch);
    goto oom;
  }
  talloc_set_type(regmatch->match_data, pcre2_match_data);

  talloc_set_destructor(regmatch, _pcre2_match_data_free);

  return regmatch;
}

/*
 *######################################
 *#    FUNCTIONS FOR POSIX-REGEX      #
 *######################################
 */
#  else
/*
 *  Wrapper functions for POSIX like, and extended regular
 *  expressions.  These use the system regex library.
 */

/** Free heap allocated regex_t structure
 *
 * Heap allocation of regex_t is needed so regex_compile has the same signature with
 * POSIX or libpcre.
 *
 * @param preg to free.
 */
static int _regex_free(regex_t *preg)
{
  regfree(preg);

  return 0;
}

/** Binary safe wrapper around regcomp
 *
 * If we have the BSD extensions we don't need to do any special work
 * if we don't have the BSD extensions we need to check to see if the
 * regular expression contains any \0 bytes.
 *
 * If it does we fail and print the appropriate error message.
 *
 * @note Compiled expression must be freed with talloc_free.
 *
 * @param[in] ctx   To allocate memory in.
 * @param[out] out    Where to write out a pointer
 *        to the structure containing the compiled expression.
 * @param[in] pattern   to compile.
 * @param[in] len   of pattern.
 * @param[in] flags   controlling matching.  May be NULL.
 * @param[in] subcaptures Whether to compile the regular expression
 *        to store subcapture data.
 * @param[in] runtime   Whether the compilation is being done at runtime.
 * @return
 *  - >= 1 on success.
 *  - <= 0 on error. Negative value is offset of parse error.
 *  With POSIX regex we only give the correct offset for embedded \0 errors.
 */
ssize_t regex_compile(TALLOC_CTX *ctx, regex_t **out, char const *pattern, size_t len,
          fr_regex_flags_t const *flags, bool subcaptures, UNUSED bool runtime)
{
  int ret;
  int cflags = REG_EXTENDED;
  regex_t *preg;

  if (len == 0) {
    fr_strerror_const("Empty expression");
    return 0;
  }

  /*
   *  Options
   */
  if (flags) {
    if (flags->global) {
      fr_strerror_const("g - Global matching/substitution not supported with posix-regex");
      return 0;
    }
    if (flags->dot_all) {
      fr_strerror_const("s - Single line matching is not supported with posix-regex");
      return 0;
    }
    if (flags->unicode) {
      fr_strerror_const("u - Unicode matching not supported with posix-regex");
      return 0;
    }
    if (flags->extended) {
      fr_strerror_const("x - Whitespace and comments not supported with posix-regex");
      return 0;
    }

    if (flags->ignore_case) cflags |= REG_ICASE;
    if (flags->multiline) cflags |= REG_NEWLINE;
  }


  if (!subcaptures) cflags |= REG_NOSUB;

#ifndef HAVE_REGNCOMP
  {
    char const *p;

    p = pattern;
    p += strlen(pattern);

    if ((size_t)(p - pattern) != len) {
      fr_strerror_printf("Found null in pattern at offset %zu.  Pattern unsafe for compilation",
             (p - pattern));
      return -(p - pattern);
    }

    preg = talloc_zero(ctx, regex_t);
    if (!preg) return 0;

    ret = regcomp(preg, pattern, cflags);
  }
#else
  preg = talloc_zero(ctx, regex_t);
  if (!preg) return 0;
  ret = regncomp(preg, pattern, len, cflags);
#endif
  if (ret != 0) {
    char errbuf[128];

    regerror(ret, preg, errbuf, sizeof(errbuf));
    fr_strerror_printf("%s", errbuf);

    talloc_free(preg);

    return 0; /* POSIX expressions don't give us the failure offset */
  }

  talloc_set_destructor(preg, _regex_free);
  *out = preg;

  return len;
}

/** Binary safe wrapper around regexec
 *
 * If we have the BSD extensions we don't need to do any special work
 * If we don't have the BSD extensions we need to check to see if the
 * value to be compared contains any \0 bytes.
 *
 * If it does, we fail and print the appropriate error message.
 *
 * @param[in] preg  The compiled expression.
 * @param[in] subject to match.
 * @param[in] regmatch  Match result structure.
 * @return
 *  - -1 on failure.
 *  - 0 on no match.
 *  - 1 on match.
 */
int regex_exec(regex_t *preg, char const *subject, size_t len, fr_regmatch_t *regmatch)
{
  int ret;
  size_t  matches;

  /*
   *  Disable capturing
   */
  if (!regmatch) {
    matches = 0;
  } else {
    matches = regmatch->allocd;

    /*
     *  Reset the match result structure
     */
    memset(regmatch->match_data, 0, sizeof(regmatch->match_data[0]) * matches);
    regmatch->used = 0;
  }

#ifndef HAVE_REGNEXEC
  {
    char const *p;

    p = subject;
    p += strlen(subject);

    if ((size_t)(p - subject) != len) {
      fr_strerror_printf("Found null in subject at offset %zu.  String unsafe for evaluation",
             (p - subject));
      if (regmatch) regmatch->used = 0;
      return -1;
    }
    ret = regexec(preg, subject, matches, regmatch ? regmatch->match_data : NULL, 0);
  }
#else
  ret = regnexec(preg, subject, len, matches, regmatch ? regmatch->match_data : NULL, 0);
#endif
  if (ret != 0) {
    if (ret != REG_NOMATCH) {
      char errbuf[128];

      regerror(ret, preg, errbuf, sizeof(errbuf));

      fr_strerror_printf("regex evaluation failed: %s", errbuf);
      return -1;
    }
    return 0;
  }

  /*
   *  Update regmatch->count to be the maximum number of
   *  groups that *could* have been populated as we don't
   *  have the number of matches.
   */
  if (regmatch) {
    regmatch->used = preg->re_nsub + 1;

    if (regmatch->subject) talloc_const_free(regmatch->subject);
    regmatch->subject = talloc_bstrndup(regmatch, subject, len);
    if (!regmatch->subject) {
      fr_strerror_const("Out of memory");
      return -1;
    }
  }
  return 1;
}

/** Returns the number of subcapture groups
 *
 * @return
 *  - 0 we can't determine this for POSIX regular expressions.
 */
uint32_t regex_subcapture_count(UNUSED regex_t const *preg)
{
  return 0;
}
#  endif

#  if defined(HAVE_REGEX_POSIX)
/** Allocate vectors to fill with match data
 *
 * @param[in] ctx to allocate match vectors in.
 * @param[in] count The number of vectors to allocate.
 * @return
 *  - NULL on error.
 *  - Array of match vectors.
 */
fr_regmatch_t *regex_match_data_alloc(TALLOC_CTX *ctx, uint32_t count)
{
  fr_regmatch_t *regmatch;

  /*
   *  Pre-allocate space for the match structure
   *  and for a 128b subject string.
   */
  regmatch = talloc_zero_pooled_object(ctx, fr_regmatch_t, 2, (sizeof(regmatch_t) * count) + 128);
  if (unlikely(!regmatch)) {
  error:
    fr_strerror_const("Out of memory");
    talloc_free(regmatch);
    return NULL;
  }
  regmatch->match_data = talloc_array(regmatch, regmatch_t, count);
  if (unlikely(!regmatch->match_data)) goto error;

  regmatch->allocd = count;
  regmatch->used = 0;
  regmatch->subject = NULL;

  return regmatch;
}
#  endif

/*
 *########################################
 *#         UNIVERSAL FUNCTIONS          #
 *########################################
 */

/** Parse a string containing one or more regex flags
 *
 * @param[out] err    May be NULL. If not NULL will be set to:
 *        - 0 on success.
 *        - -1 on unknown flag.
 *        - -2 on duplicate.
 * @param[out] out    Flag structure to populate.  Must be initialised to zero
 *        if this is the first call to regex_flags_parse.
 * @param[in] in    Flag string to parse.
 * @param[in] terminals   Terminal characters. If parsing ends before the buffer
 *        is exhausted, and is pointing to one of these chars
 *        it's not considered an error.
 * @param[in] err_on_dup  Error if the flag is already set.
 * @return
 *      - > 0 on success.  The number of flag bytes parsed.
 *  - <= 0 on failure.  Negative offset of first unrecognised flag.
 */
fr_slen_t regex_flags_parse(int *err, fr_regex_flags_t *out, fr_sbuff_t *in,
          fr_sbuff_term_t const *terminals, bool err_on_dup)
{
  fr_sbuff_t  our_in = FR_SBUFF(in);

  if (err) *err = 0;

  while (fr_sbuff_extend(&our_in)) {
    switch (*our_in.p) {
#define DO_REGEX_FLAG(_f, _c) \
    case _c: \
      if (err_on_dup && out->_f) { \
        fr_strerror_printf("Duplicate regex flag '%c'", *our_in.p); \
        if (err) *err = -2; \
        FR_SBUFF_ERROR_RETURN(&our_in); \
      } \
      out->_f = 1; \
      break

    DO_REGEX_FLAG(global, 'g');
    DO_REGEX_FLAG(ignore_case, 'i');
    DO_REGEX_FLAG(multiline, 'm');
    DO_REGEX_FLAG(dot_all, 's');
    DO_REGEX_FLAG(unicode, 'u');
    DO_REGEX_FLAG(extended, 'x');
#undef DO_REGEX_FLAG

    default:
      if (fr_sbuff_is_terminal(&our_in, terminals)) FR_SBUFF_SET_RETURN(in, &our_in);

      fr_strerror_printf("Unsupported regex flag '%c'", *our_in.p);
      if (err) *err = -1;
      FR_SBUFF_ERROR_RETURN(&our_in);
    }
    fr_sbuff_advance(&our_in, 1);
  }
  FR_SBUFF_SET_RETURN(in, &our_in);
}

/** Print the flags
 *
 * @param[out] sbuff  where to write flags.
 * @param[in] flags to print.
 * @return
 *  - The number of bytes written to the out buffer.
 *  - A number >= outlen if truncation has occurred.
 */
ssize_t regex_flags_print(fr_sbuff_t *sbuff, fr_regex_flags_t const *flags)
{
  fr_sbuff_t our_sbuff = FR_SBUFF(sbuff);

#define DO_REGEX_FLAG(_f, _c) \
  if (flags->_f) FR_SBUFF_IN_CHAR_RETURN(&our_sbuff, _c)

  DO_REGEX_FLAG(global, 'g');
  DO_REGEX_FLAG(ignore_case, 'i');
  DO_REGEX_FLAG(multiline, 'm');
  DO_REGEX_FLAG(dot_all, 's');
  DO_REGEX_FLAG(unicode, 'u');
  DO_REGEX_FLAG(extended, 'x');
#undef DO_REGEX_FLAG

  FR_SBUFF_SET_RETURN(sbuff, &our_sbuff);
}
#endif

/** Compare two boxes using an operator
 *
 *  @todo - allow /foo/i on the RHS
 *
 *  However, this involves allocating intermediate sbuffs for the
 *  unescaped RHS, and all kinds of extra work.  It's not overly hard,
 *  but it's something we wish to avoid for now.
 *
 * @param[in] op to use in comparison. MUST be T_OP_REG_EQ or T_OP_REG_NE
 * @param[in] a Value to compare,  MUST be FR_TYPE_STRING
 * @param[in] b uncompiled regex as FR_TYPE_STRING
 * @return
 *  - 1 if true
 *  - 0 if false
 *  - -1 on failure.
 */
int fr_regex_cmp_op(fr_token_t op, fr_value_box_t const *a, fr_value_box_t const *b)
{
  int rcode;
  TALLOC_CTX *ctx = NULL;
  size_t lhs_len;
  char const *lhs;
  regex_t *regex = NULL;

  if (!((op == T_OP_REG_EQ) || (op == T_OP_REG_NE))) {
    fr_strerror_const("Invalid operator for regex comparison");
    return -1;
  }

  if (b->type != FR_TYPE_STRING) {
    fr_strerror_const("RHS must be regular expression");
    return -1;
  }

  ctx = talloc_init_const("regex_cmp_op");
  if (!ctx) return -1;

  if ((a->type != FR_TYPE_STRING) && (a->type != FR_TYPE_OCTETS)) {
    fr_slen_t slen;
    char *p;

    slen = fr_value_box_aprint(ctx, &p, a, NULL); /* no escaping */
    if (slen < 0) return slen;

    lhs = p;
    lhs_len = slen;

  } else {
    lhs = a->vb_strvalue;
    lhs_len = a->vb_length;
  }

  if (regex_compile(ctx, &regex, b->vb_strvalue, b->vb_length, NULL, false, true) < 0) {
    talloc_free(ctx);
    return -1;
  }

#ifdef STATIC_ANALYZER
  if (!regex) {
    talloc_free(ctx);
    return -1;
  }
#endif

  rcode = regex_exec(regex, lhs, lhs_len, NULL);
  talloc_free(ctx);
  if (rcode < 0) return rcode;

  /*
   *  Invert the sense of the rcode for !~
   */
  if (op == T_OP_REG_NE) rcode = (rcode == 0);

  return rcode;
}

Coverage Report

Created: 2026-02-26 06:38