meganz / blofetcha

Site blobs fetcher and exception tracing.

blofetcha

This very simple NodeJS application is meant to archive JS bundles served on MEGA domains, which are dynamically-generated at runtime when visiting the site, and ultimately to ease tracing reported JS exceptions.

---

Requirements

For development, you will only need Node.js and a node global package, installed in your environment.

NodeJS

• Node installation on Windows

  Just go on official Node.js website and download the installer. Also, be sure to have git available in your PATH, npm might need it (You can find git here).

• Node installation on Ubuntu

  You can install nodejs and npm easily with apt install, just run the following commands.

  $ sudo apt install nodejs
  $ sudo apt install npm
  

• Other Operating Systems

  You can find more information about the installation on the official Node.js website and the official NPM website.

If the installation was successful, you should be able to run the following command.

$ node --version
vx.x.x

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Install

$ git clone https://github.com/meganz/blofetcha.git
$ cd blofetcha
$ npm install

Configure app

Some options are available through environment variables:

• NOCOMPRESS: By default, the bundles will be archived using gzip.
• MOBILE_DEVICE: What mobile device to emulate.
• ARCHIVE_PATH: Where to archive the bundles.
• DEBUG: Enable debugging mode.

Running the project

$ npm start

This will run the app in archive-only mode and exit, creating gzipped bundles as below:

$ ls -Rl archive
archive:
total 1
drwxr-xr-x 1 dc adm  0 jun. 19 14:17 1655340486-4.15.10/
-rw-r--r-- 1 dc adm 18 jun. 19 14:17 last

archive/1655340486-4.15.10:
total 3348
-rw-r--r-- 1 dc adm  410476 jun. 19 14:17 megaio.main.js.gz
-rw-r--r-- 1 dc adm  646409 jun. 19 14:17 meganz.chat.js.gz
-rw-r--r-- 1 dc adm  348825 jun. 19 14:17 meganz.embed.js.gz
-rw-r--r-- 1 dc adm 1420329 jun. 19 14:17 meganz.main.js.gz
-rw-r--r-- 1 dc adm 1237968 jun. 19 14:17 meganz.mobile.js.gz

Where 1655340486 is the timestamp, and 4.15.10 the site version.

Docker

To build the docker image execute:

docker build . -t blofetcha

To run the Docker image created above, execute:

docker run -e DISABLE_CHROME_SANDBOX=true -v /home/user/code/blofetcha/docker-archive:/archive blofetcha

NOTE: The mounted "docker-archive" volume will contain the archived Javascript files

Usage

Enter the following command to get usage information:

$ ./index.js -h

Finding where exceptions do point out:

TypeError: null is not an object
Line: 119979
Stack:
@..:119979:41
@..:165296:26
dispatch@..:9237:32

Given the above exception, you would run ./index.js 119979 which should give back:

# 119973          if (!e || !e.target.closest('.create-new-folder') &&
# 119974              (!c || !c.includes('fm-new-folder'))) {
# 119975
# 119976              var c3;
# 119977
# 119978              if (e && e.target) {
- 119979                  c3 = e.target.parentNode.className;
# 119980              }
# 119981
# 119982              if (!c3 || c3.indexOf('fm-new-folder') === -1) {
# 119983

Interactive mode and other advanced usages.

TBD.