arthusu / sourcemapper

Extract JavaScript source trees from Sourcemap files

Sourcemapper

Sourcemapper is a bit of golang to parse a sourcemap, as generated by webpack or similar, and spit out the original JavaScript files, recreating the source tree based on the file paths in the sourcemap.

An article explaining its purpose is available here: https://pulsesecurity.co.nz/articles/javascript-from-sourcemaps

Install

If you have a recent version of Go installed:

go install github.com/denandz/sourcemapper@latest

Otherwise you can clone and build:

git clone https://github.com/denandz/sourcemapper
cd sourcemapper
go get
go build

Usage

:~$ ./sourcemapper
Usage of ./sourcemapper:
  -header value
    	A header to send with the request, similar to curl's -H. Can be set multiple times, EG: "./sourcemapper --header "Cookie: session=bar" --header "Authorization: blerp"
  -help
    	Show help
  -insecure
    	Ignore invalid TLS certificates
  -output string
    	Source file output directory - REQUIRED
  -proxy string
    	Proxy URL
  -url string
    	URL or path to the Sourcemap file - REQUIRED

Sourcemapper will download or read the map file at url, and then spit the sources out into the directory defined by output.

The following example shows sourcemapper reading a .map file from Dockerhub. Note, Dockerhub have since removed this map file so the literal command below will not provide this output any more.

doi@asov:~$ ./sourcemapper -output dhubsrc -url https://hub.docker.com/public/js/client.356c14916fb23f85707f.js.map
[+] Retriving Sourcemap from https://hub.docker.com/public/js/client.356c14916fb23f85707f.js.map
[+] Read 23045027 bytes, parsing JSON
[+] Retrieved Sourcemap with version 3, containing 1828 entries
[+] Writing 9076765 bytes to dhubsrc/webpack:/js/client.356c14916fb23f85707f.js
[+] Writing 1014 bytes to dhubsrc/webpack:/webpack/bootstrap 356c14916fb23f85707f
[+] Writing 3174 bytes to dhubsrc/webpack:/app/scripts/client.js
[+] Writing 281 bytes to dhubsrc/webpack:/~/babel-runtime/helpers/interop-require-default.js
[+] Writing 151 bytes to dhubsrc/webpack:/~/babel-core/polyfill.js
{snip}
[+] Writing 271 bytes to dhubsrc/webpack:/~/rc-tooltip/~/core-js/library/fn/object/set-prototype-of.js
[+] Writing 315 bytes to dhubsrc/webpack:/~/rc-tooltip/~/core-js/library/modules/es6.object.set-prototype-of.js
[+] Writing 1044 bytes to dhubsrc/webpack:/~/rc-tooltip/~/core-js/library/modules/_set-proto.js
[+] Writing 308 bytes to dhubsrc/webpack:/~/rc-tooltip/~/core-js/library/fn/object/create.js
[+] Writing 307 bytes to dhubsrc/webpack:/~/rc-tooltip/~/core-js/library/modules/es6.object.create.js
[+] Writing 360 bytes to dhubsrc/webpack:/~/rc-animate/~/core-js/library/fn/object/define-property.js
[+] Writing 371 bytes to dhubsrc/webpack:/~/rc-animate/~/core-js/library/modules/es6.object.define-property.js
[+] Writing 1041 bytes to dhubsrc/webpack:/~/rc-animate/~/babel-runtime/helpers/createClass.js
[+] done
doi@asov:~$ cd dhubsrc/
doi@asov:~/dhubsrc$ du -hs .
20M     .
doi@asov:~/dhubsrc$ cd webpack\:/
~/         app/       js/        webpack/   (webpack)/
doi@asov:~/dhubsrc$ cd webpack\:/app/scripts/
actions/     components/  middlewares/ reducers/    selectors/   stores/      vendor/
doi@asov:~/dhubsrc$ cd webpack\:/app/scripts/components/

Limitations

Paths such as webpack:/~/src/whatever/omg.js are pretty common, so this tool cleans them up on windows.