Class: Yara::Rules

Inherits:
Object
  • Object
show all
Defined in:
ext/yara_native/Rules.c,
lib/yara.rb,
ext/yara_native/Rules.c

Overview

Encapsulates a Yara context against which you can compile rules and scan inputs.

Instance Method Summary collapse

Instance Method Details

#compile_file(filename, ns = nil) ⇒ nil

Compiles rules taken from a file by its filename. This method can be called more than once using multiple rules strings and can be used in combination with compile_file.

To avoid namespace conflicts, you can use set_namespace before compiling rules.

Returns:

  • (nil)

Parameters:

  • filename (String) —

    The name of a yara rules file to compile.

  • ns (String, nil) —

    Optional namespace for the rules.

Raises:



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# File 'ext/yara_native/Rules.c', line 70

VALUE rules_compile_file(int argc, VALUE *argv, VALUE self) {
  FILE *file;
  char *fname;
  YARA_CONTEXT *ctx;
  char error_message[256];
  NAMESPACE *orig_ns, *ns;

  VALUE rb_fname;
  VALUE rb_ns;

  orig_ns = ns = NULL;

  rb_scan_args(argc, argv, "11", &rb_fname, &rb_ns);

  Check_Type(rb_fname, T_STRING);

  if(rb_ns != Qnil) {
    Check_Type(rb_ns, T_STRING);
  }

  fname = RSTRING_PTR(rb_fname);
  if( !(file=fopen(fname, "r")) ) {
    rb_raise(error_CompileError, "No such file: %s", fname);
  } else {
    Data_Get_Struct(self, YARA_CONTEXT, ctx);

    if((rb_ns != Qnil) && (orig_ns = ctx->current_namespace)) {

      if (!(ns = find_namespace(ctx, RSTRING_PTR(rb_ns))))
        ns = yr_create_namespace(ctx, RSTRING_PTR(rb_ns));

      ctx->current_namespace = ns;
    }

    if( yr_compile_file(file, ctx) != 0 ) {
      yr_get_error_message(ctx, error_message, sizeof(error_message));
      fclose(file);
      rb_raise(error_CompileError, "Syntax Error - %s(%d): %s", fname, ctx->last_error_line, error_message);
    }

    yr_push_file_name(ctx, fname);

    if ( orig_ns )
      ctx->current_namespace = orig_ns;

    fclose(file);

    return Qtrue;
  }
}

#compile_string(rules_string, ns = nil) ⇒ nil

Compiles rules taken from a ruby string. This method can be called more than once using multiple rules strings and can be used in combination with compile_file.

To avoid namespace conflicts, you can set a namespace using the optional ‘ns’ argument.

Returns:

  • (nil)

Parameters:

  • rules_string (String) —

    A string containing yara rules text.

  • ns (String, nil) —

    An optional namespace for the rules.

Raises:



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# File 'ext/yara_native/Rules.c', line 138

VALUE rules_compile_string(int argc, VALUE *argv, VALUE self) {
  YARA_CONTEXT *ctx;
  char *rules;
  char error_message[256];
  NAMESPACE *orig_ns, *ns;

  VALUE rb_rules;
  VALUE rb_ns;

  orig_ns = ns = NULL;

  rb_scan_args(argc, argv, "11", &rb_rules, &rb_ns);

  Check_Type(rb_rules, T_STRING);
  if (rb_ns != Qnil)
    Check_Type(rb_ns, T_STRING);

  rules = RSTRING_PTR(rb_rules);
  Data_Get_Struct(self, YARA_CONTEXT, ctx);

  if((rb_ns != Qnil) && (orig_ns = ctx->current_namespace)) {
    orig_ns = ctx->current_namespace;

    if (!(ns = find_namespace(ctx, RSTRING_PTR(rb_ns))))
      ns = yr_create_namespace(ctx, RSTRING_PTR(rb_ns));

    ctx->current_namespace = ns;
  }

  if( yr_compile_string(rules, ctx) != 0) {
      yr_get_error_message(ctx, error_message, sizeof(error_message));
      rb_raise(error_CompileError, "Syntax Error - line(%d): %s", ctx->last_error_line, error_message);
  }

  if ( orig_ns )
    ctx->current_namespace = orig_ns;

  return Qtrue;
}

#current_namespace ⇒ String

Returns String Returns the name of the currently active namespace.

Returns:

  • (String)

Returns:

  • String Returns the name of the currently active namespace.



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# File 'ext/yara_native/Rules.c', line 198

VALUE rules_current_namespace(VALUE self) {
  YARA_CONTEXT *ctx;
  Data_Get_Struct(self, YARA_CONTEXT, ctx);
  if(ctx->current_namespace && ctx->current_namespace->name)
    return rb_str_new2(ctx->current_namespace->name);
  else
    return Qnil;
}

#namespaces ⇒ Array

Returns the namespaces available in this rules context.

Returns:

  • (Array)

Returns:

  • (String) —

    Returns the namespaces available in this rules context.



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# File 'ext/yara_native/Rules.c', line 213

VALUE rules_namespaces(VALUE self) {
  YARA_CONTEXT *ctx;
  NAMESPACE *ns;
  VALUE ary = rb_ary_new();

  Data_Get_Struct(self, YARA_CONTEXT, ctx);
  ns = ctx->namespaces;
  while(ns && ns->name) {
    rb_ary_push(ary, rb_str_new2(ns->name));
    ns = ns->next;
  }
  return ary;
}

#scan_file(filename) ⇒ Array

Scans a file using the compiled rules supplied with either compile_file or compile_string (or both).

Returns:

  • (Array)

Parameters:

  • filename (String) —

    The name of a file to scan with yara.

Returns:

  • (Yara::Match) —

    An array of Yara::Match objects found in the file.

Raises:



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# File 'ext/yara_native/Rules.c', line 290

VALUE rules_scan_file(VALUE self, VALUE rb_fname) {
  YARA_CONTEXT *ctx;
  VALUE results;
  unsigned int ret;
  char *fname;

  Check_Type(rb_fname, T_STRING);
  results = rb_ary_new();
  Data_Get_Struct(self, YARA_CONTEXT, ctx);
  fname = RSTRING_PTR(rb_fname);

  ret = yr_scan_file(fname, ctx, scan_callback, &results);
  if (ret == ERROR_COULD_NOT_OPEN_FILE)
    rb_raise(error_ScanError, "Could not open file: '%s'", fname);
  else if (ret != 0)
    rb_raise(error_ScanError, "A error occurred while scanning: %s", 
        ((ret > MAX_SCAN_ERROR)? "unknown error" : SCAN_ERRORS[ret]));

  return results;
}

#scan_string(buf) ⇒ Array

Scans a ruby string using the compiled rules supplied with either compile_file or compile_string (or both).

Returns:

  • (Array)

Parameters:

  • buf (String) —

    The string buffer to scan with yara.

Returns:

  • (Yara::Match) —

    An array of Yara::Match objects found in the string.

Raises:

  • (Yara::ScanError) —

    Raised if an error occurs while scanning the string.



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# File 'ext/yara_native/Rules.c', line 325

VALUE rules_scan_string(VALUE self, VALUE rb_dat) {
  YARA_CONTEXT *ctx;
  VALUE results;
  char *buf;
  size_t buflen;
  int ret;

  Check_Type(rb_dat, T_STRING);
  buf = RSTRING_PTR(rb_dat);
  buflen = RSTRING_LEN(rb_dat);

  results = rb_ary_new();

  Data_Get_Struct(self, YARA_CONTEXT, ctx);

  ret = yr_scan_mem(buf, buflen, ctx, scan_callback, &results);
  if (ret != 0)
    rb_raise(error_ScanError, "A error occurred while scanning: %s", 
        ((ret > MAX_SCAN_ERROR)? "unknown error" : SCAN_ERRORS[ret]));

  return results;
}

#set_namespace(name) ⇒ nil

Sets the current namespace to the given name. If the namespace does not yet exist it is added.

To avoid namespace conflicts, you can use set_namespace before compiling rules.

Returns:

  • (nil)

Parameters:

  • name (String) —

    The namespace to set.



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# File 'ext/yara_native/Rules.c', line 239

VALUE rules_set_namespace(VALUE self, VALUE rb_namespace) {
  YARA_CONTEXT *ctx;
  NAMESPACE *ns = NULL;
  const char *name;

  Check_Type(rb_namespace, T_STRING);
  name = RSTRING_PTR(rb_namespace);

  Data_Get_Struct(self, YARA_CONTEXT, ctx);

  if (!(ns = find_namespace(ctx, name)))
      ns = yr_create_namespace(ctx, name);

  if (ns) {
    ctx->current_namespace = ns;
    return rb_namespace;
  } else {
    return Qnil;
  }

}

#weight ⇒ Fixnum

Fixnum returns a weight value for the compiled rules.

Returns:

  • (Fixnum)

Returns:

  • Fixnum returns a weight value for the compiled rules.



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# File 'ext/yara_native/Rules.c', line 186

VALUE rules_weight(VALUE self) {
  YARA_CONTEXT *ctx;
  Data_Get_Struct(self, YARA_CONTEXT, ctx);
  return INT2NUM(yr_calculate_rules_weight(ctx));
}