yarac.c

/*
Copyright (c) 2013. The YARA Authors. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

#ifndef _WIN32

#include <sys/stat.h>
#include <dirent.h>
#include <unistd.h>
#include <time.h>

#else

#include <windows.h>

#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <yara.h>

#include "args.h"
#include "config.h"

#ifndef MAX_PATH
#define MAX_PATH 255
#endif

#define MAX_ARGS_EXT_VAR   32


char* ext_vars[MAX_ARGS_EXT_VAR + 1];
int ignore_warnings = FALSE;
int show_version = FALSE;
int show_help = FALSE;


#define USAGE_STRING \
    "Usage: yarac [OPTION]... [NAMESPACE:]SOURCE_FILE... OUTPUT_FILE"

args_option_t options[] =
{
  OPT_STRING_MULTI('d', NULL, &ext_vars, MAX_ARGS_EXT_VAR,
      "define external variable", "VAR=VALUE"),

  OPT_BOOLEAN('w', "no-warnings", &ignore_warnings,
      "disable warnings"),

  OPT_BOOLEAN('v', "version", &show_version,
      "show version information"),

  OPT_BOOLEAN('h', "help", &show_help,
      "show this help and exit"),

  OPT_END()
};


int is_numeric(
    const char *str)
{
  while(*str)
  {
    if (!isdigit(*str))
      return 0;
    str++;
  }

  return 1;
}


void report_error(
    int error_level,
    const char* file_name,
    int line_number,
    const char* message,
    void* user_data)
{
  if (error_level == YARA_ERROR_LEVEL_ERROR)
  {
    fprintf(stderr, "%s(%d): error: %s\n", file_name, line_number, message);
  }
  else
  {
    if (!ignore_warnings)
      fprintf(stderr, "%s(%d): warning: %s\n", file_name, line_number, message);
  }
}


int define_external_variables(
    YR_COMPILER* compiler)
{
  for (int i = 0; ext_vars[i] != NULL; i++)
  {
    char* equal_sign = strchr(ext_vars[i], '=');

    if (!equal_sign)
    {
      fprintf(stderr, "error: wrong syntax for `-d` option.\n");
      return FALSE;
    }

    // Replace the equal sign with null character to split the external
    // variable definition (i.e: myvar=somevalue) in two strings: identifier
    // and value.

    *equal_sign = '\0';

    char* identifier = ext_vars[i];
    char* value = equal_sign + 1;

    if (is_numeric(value))
    {
      yr_compiler_define_integer_variable(
          compiler,
          identifier,
          atoi(value));
    }
    else if (strcmp(value, "true") == 0 || strcmp(value, "false") == 0)
    {
      yr_compiler_define_boolean_variable(
          compiler,
          identifier,
          strcmp(value, "true") == 0);
    }
    else
    {
      yr_compiler_define_string_variable(
          compiler,
          identifier,
          value);
    }
  }

  return TRUE;
}


#define exit_with_code(code) { result = code; goto _exit; }


int main(
    int argc,
    const char** argv)
{
  YR_COMPILER* compiler = NULL;
  YR_RULES* rules = NULL;

  int result;

  argc = args_parse(options, argc, argv);

  if (show_version)
  {
    printf("%s\n", PACKAGE_STRING);
    printf("\nSend bug reports and suggestions to: %s.\n", PACKAGE_BUGREPORT);

    return EXIT_FAILURE;
  }

  if (show_help)
  {
    printf("%s\n\n", USAGE_STRING);

    args_print_usage(options, 25);
    printf("\nSend bug reports and suggestions to: %s.\n", PACKAGE_BUGREPORT);

    return EXIT_FAILURE;
  }

  if (argc < 2)
  {
    fprintf(stderr, "yarac: wrong number of arguments\n");
    fprintf(stderr, "%s\n\n", USAGE_STRING);
    fprintf(stderr, "Try `--help` for more options\n");

    exit_with_code(EXIT_FAILURE);
  }

  result = yr_initialize();

  if (result != ERROR_SUCCESS)
    exit_with_code(EXIT_FAILURE);

  if (yr_compiler_create(&compiler) != ERROR_SUCCESS)
    exit_with_code(EXIT_FAILURE);

  if (!define_external_variables(compiler))
    exit_with_code(EXIT_FAILURE);

  yr_compiler_set_callback(compiler, report_error, NULL);

  for (int i = 0; i < argc - 1; i++)
  {
    const char* ns;
    const char* file_name;
    char* colon = (char*) strchr(argv[i], ':');

    if (colon)
    {
      file_name = colon + 1;
      *colon = '\0';
      ns = argv[i];
    }
    else
    {
      file_name = argv[i];
      ns = NULL;
    }

    FILE* rule_file = fopen(file_name, "r");

    if (rule_file != NULL)
    {
      int errors = yr_compiler_add_file(
          compiler, rule_file, ns, file_name);

      fclose(rule_file);

      if (errors) // errors during compilation
        exit_with_code(EXIT_FAILURE);
    }
    else
    {
      fprintf(stderr, "error: could not open file: %s\n", file_name);
    }
  }

  result = yr_compiler_get_rules(compiler, &rules);

  if (result != ERROR_SUCCESS)
  {
    fprintf(stderr, "error: %d\n", result);
    exit_with_code(EXIT_FAILURE);
  }

  result = yr_rules_save(rules, argv[argc - 1]);

  if (result != ERROR_SUCCESS)
  {
    fprintf(stderr, "error: %d\n", result);
    exit_with_code(EXIT_FAILURE);
  }

  result = EXIT_SUCCESS;

_exit:

  if (compiler != NULL)
    yr_compiler_destroy(compiler);

  if (rules != NULL)
    yr_rules_destroy(rules);

  yr_finalize();

  return result;
}