OPPA

A toolkit to generate OpenAPI specifications.

Installation ✍️

oppa requires Go 1.22+ to install successfully.

CGO_ENABLED=1 go install github.com/oneaudit/oppa/cmd/oppa@latest

Usage 📚

oppa -h

This will display help for the tool. Here are all the switches it supports.

Oppa is a toolkit to generate OpenAPI specifications from JSON lines.

Usage:
  oppa [flags]

Flags:
TARGET:
   -t, -target string       target input file to parse
   -im, -input-mode string  mode of input file (jsonl, logger++) (default "jsonl")

CONFIGURATION:
   -config string  path to the oppa configuration file

TUNING:
   -no-origin, -n                     By default, oppa adds an Origin header to all paths.
   -keep-404, -k4                     By default, oppa skips file endpoint with a 404 code.
   -filter-regex, -fr string[]        Skip endpoints based on a regex.
   -filter-regex-base, -frb string[]  Skip endpoints based on a regex.

OUTPUT:
   -d, -output-dir string  store openapi to custom directory
   -silent                 display output only
   -v, -verbose            display verbose output
   -debug                  display debug output
   -version                display project version

Running Oppa 🧪

Oppa implements a strange and unconventional merge logic. Oppa lacks knowledge on the parameters in each request. To avoid losing information, Oppa creates one openapi entry for each unique URL.

• https://example.com/?page=index
• https://example.com/?page=home

This results in a strange OpenAPI file. This unconventional approach make it easier to test multiple query parameter combinations with nuclei without editing the tool.

  /:
    get:
      parameters:
        - in: query
          name: page
          schema:
            default: index
            type: string
      responses:
        default:
          description: ""
  //:
    get:
      parameters:
        - in: query
          name: page
          schema:
            default: home
            type: string
      responses:
        default:
          description: ""

JSON Lines Input

Oppa can work from Katana JSON Lines output file format. By default, generated files are stored in the oppa_openapi folder.

$ katana -u https://example.com -jsonl -o requests.txt
$ oppa -im jsonl -t requests.txt

Examples

On a GLPI project with directory listing, we can use:

oppa -config config.yaml -target katana.txt -fr "^/icons/" -fr "^/src/" -fr "^/pics/" -fr "^/templates/" -fr "^/css_compiled/"