DEV: Allow webmock to intercept FinalDestination::HTTP requests (#20575)

lib/final_destination/http.rb

@@ -1,40 +1,47 @@
 # frozen_string_literal: true
 
-class FinalDestination::HTTP < Net::HTTP
-  def connect
-    original_open_timeout = @open_timeout
-    return super if @ipaddr
+class FinalDestination
+  module SSRFSafeNetHTTP
+    def connect
+      original_open_timeout = @open_timeout
+      return super if @ipaddr
 
-    timeout_at = current_time + @open_timeout
+      timeout_at = current_time + @open_timeout
 
-    # This iteration through addresses would normally happen in Socket#tcp
-    # We do it here because we're tightly controlling addresses rather than
-    # handing Socket#tcp a hostname
-    ips = FinalDestination::SSRFDetector.lookup_and_filter_ips(@address, timeout: @connect_timeout)
+      # This iteration through addresses would normally happen in Socket#tcp
+      # We do it here because we're tightly controlling addresses rather than
+      # handing Socket#tcp a hostname
+      ips =
+        FinalDestination::SSRFDetector.lookup_and_filter_ips(@address, timeout: @connect_timeout)
 
-    ips.each_with_index do |ip, index|
-      debug "[FinalDestination] Attempting connection to #{ip}..."
-      self.ipaddr = ip
+      ips.each_with_index do |ip, index|
+        debug "[FinalDestination] Attempting connection to #{ip}..."
+        self.ipaddr = ip
 
-      remaining_time = timeout_at - current_time
-      if remaining_time <= 0
-        raise Net::OpenTimeout.new("Operation timed out - FinalDestination::HTTP")
+        remaining_time = timeout_at - current_time
+        if remaining_time <= 0
+          raise Net::OpenTimeout.new("Operation timed out - FinalDestination::HTTP")
+        end
+
+        @open_timeout = remaining_time
+        return super
+      rescue SystemCallError, Net::OpenTimeout => e
+        debug "[FinalDestination] Error connecting to #{ip}... #{e.message}"
+        was_last_attempt = index == ips.length - 1
+        raise if was_last_attempt
       end
-
-      @open_timeout = remaining_time
-      return super
-    rescue SystemCallError, Net::OpenTimeout => e
-      debug "[FinalDestination] Error connecting to #{ip}... #{e.message}"
-      was_last_attempt = index == ips.length - 1
-      raise if was_last_attempt
+    ensure
+      @open_timeout = original_open_timeout
+    end
+
+    private
+
+    def current_time
+      Process.clock_gettime(Process::CLOCK_MONOTONIC)
     end
-  ensure
-    @open_timeout = original_open_timeout
   end
 
-  private
-
-  def current_time
-    Process.clock_gettime(Process::CLOCK_MONOTONIC)
+  class HTTP < ::Net::HTTP
+    include SSRFSafeNetHTTP
   end
 end

spec/support/final_destination_helper.rb

@@ -7,7 +7,15 @@ WebMock::HttpLibAdapterRegistry.instance.register(
 
     def self.enable!
       FinalDestination.send(:remove_const, :HTTP)
-      FinalDestination.send(:const_set, :HTTP, Net::HTTP)
+
+      # At this point, `Net::HTTP` has already been patched by WebMock so we need to re-declare `FinalDestination::HTTP`
+      # but inherit from the patched `Net::HTTP` class. This is to allow requests made using `FinalDestination::HTTP` to be
+      # intercepted by WebMock.
+      FinalDestination.send(
+        :const_set,
+        :HTTP,
+        Class.new(Net::HTTP) { include FinalDestination::SSRFSafeNetHTTP },
+      )
     end
 
     def self.disable!