DataPower has a number of features that can be enabled in API Connect with Gateway extensions. One of these is the DotDot feature that Allow requests that contain .. in the URL. To look at other features that can be enabled take a look here - https://www.ibm.com/docs/en/datapower-gateway/10.5.x?topic=commands-allowed-features

Create the Gateway Extension

To enable the DotDot feature you need to create a cfg file that extends the FrontSideHandler (FSH) in datapower. If you look at the allowed-features line in the sample below you can see DotDot is concatenated to the end of the string with a + as a separator.

top
co
source-https apiconnect_https_9443
  allowed-features HTTP-1.0+HTTP-1.1+HTTP-2.0+POST+GET+PUT+PATCH+HEAD+OPTIONS+TRACE+DELETE+CustomMethods+QueryString+FragmentIdentifiers+DotDot
exit

This needs to be zipped with a command like

zip dotdot-fsh.zip dotdot.cfg

Then a manifest is required like below

manifest.json

{
   "extension":{
      "files":[
         {
            "filename":"dotdot-fsh.zip",
            "deploy":"immediate",
            "type":"extension"
         }
      ]
   }
}

Then a zip of both the manifest and the fsh zip must be created

zip dotdot.zip manifest.json dotdot-fsh.zip

Load the Gateway Extension

Login to API Connect Cloud Manager Admin, go to topology, select the gateway and click on configure gateway extension.

Click on Add and upload the zip file created in step above and press save

Wait a few minutes for the extension to apply

Once gateway extension is applied you can see that the FSH is updated to include the DotDot feature.