smsgate

smsgate is a small time, two piece portal software to receive messages from your android phone and forward them to a HTTP API and view them on a browser anywhere. This piece of software was created with the premise of several people in different locations being able to access the latest received messages from an android phone. A very common use case of this is for several people to access two step verification codes, single one time codes for different types of applications.

smsgate is divided in two parts: smsgate the socket.io/express server and smsrelay2 the react-native android application. This includes an Android application in react-native that listens for sms messages both foreground and background but not when closed. This application executes a fetch request to the server once it receives a message pushing it to every connected client. There's also an express/socket.io server to interface with the users browsers, socket.io allows for clients to be connected to the server and receive any incoming messages in real time.

Visual Demo

Base scenario (failed login, valid login, message reception, close session, login with messages, saved session, invalid token redirect)

Android application screenshot

Main specification/features

React-native android application
Foreground and background sms listener
Simple user interface
Notification sound
Socket.io/Express server
Real-time sms reception (~ 1 second)
Token based authentication, SHA-512 hash with salt (local/session storage)
Pseudo uni-directional communications (reception only)
Translation ready through simple json file

Getting started

Clone this repository, install dependencies, add your variables and run.

Clone repository
$ git clone https://github.com/eduardomota/smsgate

Install smsgate dependencies
$ cd ./smsgate/smsgate
$ npm install

Install smsrelay2 dependencies
$ cd ../smsrelay2/
$ npm install

Change the variables to suit your preferences, on these files:

Android application: ./smsrelay2/config.js
Express/socketio client: ./smsgate/js/app/config.js
Express/socketio server: ./smsgate/config.js
Express/socketio client/phone test: ./smsgate/js/test.js

smsrelay2

smsrelay2 listens for incoming messages to then forward them to the server, on sending it compiles the origin (from), body (data within the message) and current date formatted as hh:mm:ss dd/mm/yyyy. These parameters can be changed in the code as needed. When opening the app the first time you'll notice that it contains an excerpt of the application configuration but redacted so its not readily visible but able to help troubleshooting issues at distance.

To launch the app, connect a physical device and type:

$ npx react-native run-android

smsgate

smsgate receives messages from devices that are both authenticated by the authorization and x-clientid headers included in every communication with the server. The server retains the latest 10 messages it receives and broadcasts using socket.io to every connected client. Every connected client has to be authorized by using a valid authorization header that is generated using the login page and inserting the correct access code, it then hashes the code with a salt and sets as its auth header.

To run the smsgate server type:

$ node ./index.js

Considerations

This application authentication only makes sense if used under TLS, it uses a salt and strong hashing algorithm to harden against potential rainbow tables against access codes. Using this over plain HTTP defeats the purpose of using a token as it can be easily obtained from raw network traffic. Tokens cannot be created using "crypto.subtle.digest" over HTTP, for that you'll need enable insecure inside on config. This application is made with modern browsers in mind, older browsers may encounter difficulties or may not function as expected. Chrome is the recommended browser as it implements all functionality in an ideal scenario but any other modern popular browser will probably work well. A way of avoiding white screen flash when changing pages is implemented using prefetch/prerender functionality, Safari isn't supported.

Notes

Translation

Just access ./smsgate/js/app/lang and create a new .json language file, change key values to the target language accordingly and set it on the config file to use it.

Regarding android compilation

Follow the general guide to export an APK with code signing. You may need to set react native sha512 library compileSdk directive to at least 28 to be able to compile the apk.