body_rule.rb in contrast-agent-7.3.1

- old
+ new

@@ -1,10 +1,11 @@
 # Copyright (c) 2023 Contrast Security, Inc. See https://www.contrastsecurity.com/enduser-terms-0317a for more details.
 # frozen_string_literal: true
 
 require 'rack'
 require 'contrast/utils/hash_digest'
+require 'contrast/utils/duck_utils'
 require 'contrast/utils/string_utils'
 require 'contrast/agent/assess/rule/response/base_rule'
 
 module Contrast
   module Agent
@@ -42,24 +43,38 @@
             #
             # @param section [String,nil] html section to find element
             # @param element_start_str [String] element to find in html section
             # @return [Array<Hash>] the found elements of this section, as well as their start and end indexes.
             def html_elements section, element_start_str = '', capture_overflow: false
+              return [] unless section
+              return [] unless (potentials = potential_elements(section, element_start_str).flatten).any?
+
               elements = []
               section_start = 0
-              return [] unless section
 
-              potential_elements(section, element_start_str).flatten.each do |potential_element|
+              potentials.each do |potential_element|
                 next unless potential_element
                 next unless element_openings.any? { |opening| potential_element.start_with?(opening) }
 
-                section_start = section.index(element_start_str, section_start)
-                next unless section_start
+                start = section&.index(element_start_str, section_start)
+                next if Contrast::Utils::DuckUtils.empty_duck?(start)
 
-                element_stop = potential_element.index('>').to_i
-                next unless element_stop
+                stop = potential_element.index('>').to_i
+                next if Contrast::Utils::DuckUtils.empty_duck?(stop)
 
-                section_close = section_start + 6 + element_stop
+                section_close = start + 6 + stop
+                # Now we have valid tag section with start and stop.
+                # Save new boundaries. This is to make sure that If
+                # on previous iteration there were non valid section,
+                # the start_section will be assigned to nil, thus making
+                # the detection of new section not possible, and throwing
+                # an error. To that end old values are kept safe.
+                #
+                # Assign new start index.
+                section_start = start
+                # Assign new end index.
+                element_stop = stop
+
                 elements << capture(section, section_start, section_close, element_stop, overflow: capture_overflow)
                 section_start = section_close
               end
               elements
             end