WhatsApp Web server documentation

[valsov]

Hi everyone, I'm in the process of developing a basic WhatsApp Web server which could replace a real WhatsApp Web server, with restricted features.
The aim is to be able to do end-to-end testing of my project (which uses this library) without calling the real WhatsApp server. The server would have some routes to query which messages were sent and received, so we can compare the observed state with the desired.

Do you have/know any resource which could help me understand the routes and protocols used by WhatsApp Web? I haven't found anything, which is to be expected because unofficial clients aren't supported by WhatsApp.
I started exploring this library's internals but it is really time consuming to deduct what the server should send and accept.

The scope of the "mock" server is:

• QR code generation
• QR code validation
• Session management
• Send message
• Receive message

Thank you for your help!

[masewo]

Tried the same, but because of the complexity I switched to a simpler approach and started mocking the whatsmeow interface. Not the same level of integration but works fine for me until now.

[Manjit2003]

Well, WhatsApp's server doesn't do much other than just acting as a signalling server between two clients. All the Signal protocol stuff is mostly handled at the client side. Yes you might need to look into noise protocol for the initial transport, you can use the Binary encoder & decoder from whatsmeow. After that, most of the stuff would be reading the binary nodes and transferring the content to the correct jid

[Manjit2003]

best bet would be starting from writing a client like whatsmeow in simple lanuage like python/js as most of the stuff is handled on the client.

your flow would be :

Handle the incoming noise handshake.
Break websocket messages into correct frame using encoder
the qrs are generated in client side
Handle the login message from the phone (look into the java implementation for reference)
Manage & send pre key pairs to clients
act as a bridge between two authenticated sessions

[valsov]

I actually need to emulate a client inside the mock WhatsApp server and use it to interact with the client which uses whatsmeow.
Thank you for those tips, I will use this library for the handshake and encoding/decoding. I should also be able to use the proto structs.