Class: Datadog::AppSec::WAF::Context

Inherits:
Object
  • Object
show all
Defined in:
lib/datadog/appsec/waf/context.rb

Overview

Ruby representation of the ddwaf_context in libddwaf See github.com/DataDog/libddwaf/blob/10e3a1dfc7bc9bb8ab11a09a9f8b6b339eaf3271/BINDING_IMPL_NOTES.md?plain=1#L125-L158

Constant Summary collapse

EMPTY_RESULT = 
{
  "events" => [],     #: WAF::events
  "actions" => {},    #: WAF::actions
  "attributes" => {}, #: WAF::attributes
  "duration" => 0,
  "timeout" => false,
  "keep" => false
}.freeze
SUCCESS_RESULT_CODES = 
%i[ddwaf_ok ddwaf_match].freeze
RESULT_CODE_TO_STATUS = 
{
  ddwaf_ok: :ok,
  ddwaf_match: :match,
  ddwaf_err_internal: :err_internal,
  ddwaf_err_invalid_object: :err_invalid_object,
  ddwaf_err_invalid_argument: :err_invalid_argument
}.freeze

Instance Method Summary collapse

Constructor Details

#initialize(context_ptr) ⇒ Context

Returns a new instance of Context.



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# File 'lib/datadog/appsec/waf/context.rb', line 26

def initialize(context_ptr)
  @context_ptr = context_ptr
end

Instance Method Details

#finalize! ⇒ Object

Destroys the WAF context and sets the pointer to nil.

The instance becomes unusable after this method is called.



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# File 'lib/datadog/appsec/waf/context.rb', line 33

def finalize!
  context_ptr_to_destroy = @context_ptr
  @context_ptr = nil

  retained.each do |retained_obj|
    next unless retained_obj.is_a?(LibDDWAF::Object)

    LibDDWAF.ddwaf_object_free(retained_obj)
  end

  retained.clear
  LibDDWAF.ddwaf_context_destroy(context_ptr_to_destroy)
end

#run(persistent_data, ephemeral_data, timeout = LibDDWAF::DDWAF_RUN_TIMEOUT) ⇒ Result

Runs the WAF context with the given persistent and ephemeral data.

Returns:

  • (Result) —

    the result of the WAF run

Raises:

  • (ConversionError) —

    if the conversion of persistent or ephemeral data fails

  • (LibDDWAFError) —

    if libddwaf could not create the result object



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# File 'lib/datadog/appsec/waf/context.rb', line 53

def run(persistent_data, ephemeral_data, timeout = LibDDWAF::DDWAF_RUN_TIMEOUT)
  ensure_pointer_presence!

  persistent_data_obj = Converter.ruby_to_object(
    persistent_data,
    max_container_size: LibDDWAF::DDWAF_MAX_CONTAINER_SIZE,
    max_container_depth: LibDDWAF::DDWAF_MAX_CONTAINER_DEPTH,
    max_string_length: LibDDWAF::DDWAF_MAX_STRING_LENGTH,
    coerce: false
  )
  if persistent_data_obj.null?
    raise ConversionError, "Could not convert persistent data: #{persistent_data.inspect}"
  end

  # retain C objects in memory for subsequent calls to run
  retain(persistent_data_obj)

  ephemeral_data_obj = Converter.ruby_to_object(
    ephemeral_data,
    max_container_size: LibDDWAF::DDWAF_MAX_CONTAINER_SIZE,
    max_container_depth: LibDDWAF::DDWAF_MAX_CONTAINER_DEPTH,
    max_string_length: LibDDWAF::DDWAF_MAX_STRING_LENGTH,
    coerce: false
  )
  if ephemeral_data_obj.null?
    raise ConversionError, "Could not convert ephemeral data: #{ephemeral_data.inspect}"
  end

  result_obj = LibDDWAF::Object.new
  raise LibDDWAFError, "Could not create result object" if result_obj.null?

  code = LibDDWAF.ddwaf_run(@context_ptr, persistent_data_obj, ephemeral_data_obj, result_obj, timeout)
  result = Converter.object_to_ruby(result_obj)

  # NOTE: In case of the error, `libddwaf` will not "fill" the result
  #       object, so it will be empty and the conversion of it will return
  #       `nil`, but that is not a conversion issue.
  if SUCCESS_RESULT_CODES.include?(code) && result.nil?
    raise ConversionError, "Could not convert result into object: #{code}"
  end

  result ||= EMPTY_RESULT
  result = Result.new(
    status: RESULT_CODE_TO_STATUS[code],
    events: result["events"],
    actions: result["actions"],
    attributes: result["attributes"],
    duration: result["duration"],
    timeout: result["timeout"],
    keep: result["keep"]
  )

  if persistent_data_obj.truncated? || ephemeral_data_obj.truncated?
    result.mark_input_truncated!
  end

  result
ensure
  LibDDWAF.ddwaf_object_free(result_obj) if result_obj
  LibDDWAF.ddwaf_object_free(ephemeral_data_obj) if ephemeral_data_obj
end