https://github.com/tarunkoyalwar/nestle

Match and Extract Nested groups (ex: graphql) using regex with Nestle
https://github.com/tarunkoyalwar/nestle

automation bugbounty bugbounty-tool go graphql javascript-recon javascript-regex recon regex

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Match and Extract Nested groups (ex: graphql) using regex with Nestle

• Host: GitHub
• URL: https://github.com/tarunkoyalwar/nestle
• Owner: tarunKoyalwar
• License: mit
• Created: 2022-10-26T15:02:23.000Z (about 2 years ago)
• Default Branch: main
• Last Pushed: 2022-11-04T22:14:18.000Z (about 2 years ago)
• Last Synced: 2024-06-21T13:21:36.261Z (5 months ago)
• Topics: automation, bugbounty, bugbounty-tool, go, graphql, javascript-recon, javascript-regex, recon, regex
• Language: Go
• Homepage:
• Size: 244 KB
• Stars: 6
• Watchers: 1
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Nestle







A simple and easy to use wrapper around **regex.Regexp** that allows parsing nested objected like brackets,parenthesis etc . The syntax to validate and match a nested group is `[{:nested:}]` this syntax or match group will validate and match balanced curly brackets.

## Why ??

There may be lot of cases where this can be used but **nestle** is primarily developed with a use case to extract embedded graphql queries from js files which traditionally is not easy and may not be possible due to nested object fields Ex `me { id address {street location }}`. However this can easily be matched and extracted using nestle .

### How does this work ??

Implementaion of `nestle` is simple it uses 2 regex instances one for regex before say `{` (Prematch group) and another instance for regex after `}` (PostMatch group) .Indexes of these two groups are obtained using `regexp.Regexp.FindAllStringIndex` and continuity and whether the parenthesis are balanced  is validated using a simple expression evaluation algorithm which uses **stack**

### Example/Usecase

Extract embedded graphql queries from javascript files 

~~~

cat js-file.js | nestle -regex '(query|mutation)\s+[a-zA-Z]+[0-9]*[a-zA-Z]+(\([^(\(|\))]+\))*\s*[{:nested:}]'

~~~

Above is 100% working example to extract entire graphql query . A sample graphql text file is located at [graphql.txt](./static/testcase_graphql.txt)

## Disclaimer

1. Nestle Only supports regex that have `:nested:` syntax since it is explicitly designed for this purposes .

2. Nestle currently does not support normal/other/simple regex since there are better options available.

3. Case where regex query only matches parenthesis ex: `[(:nested:)]` is discouraged and blacklisted 

## Installation 

- Install from source

```sh

go install -v github.com/tarunKoyalwar/nestle/cmd/nestle@latest

```

- Install from Releases

## Usage 

Using nestle with syntax `[:nested:]` . is simple which can be better understood using below example

**Example**

- Objective :  extract user data ` user {xxx} ` from below graphql query 

~~~

query me{

    me {

        id

        username

        user {

            address {

                street

                city

            }

            contact {

                email

                phone

            }

        }

    }

}

~~~

to extract `user {xxx}` including all data between them with parenthesis use regex

~~~

(user)\s+[{:nested:}]

~~~

and that's it . Here nested group is denoted using **[ start_char : nested : end_char ]**

Other examples are available in `nestle_test.go` file and a sample file is available at [graphql.txt](./static/testcase_graphql.txt)

Run below command for help

```sh

nestle -h

```

# Support

Do start the repo if you liked the project to keeep motivated  and create interesting projects