# Contributing

This is based on information seen [here](https://github.com/mgp25/Instagram-API/wiki/Technical-information).

#### Table of contents

 1. [Common Errors](#common-errors)
 2. [Capturing Endpoints](#capturing-endpoints)
 3. [Reading the Signature Key](#reading-the-signature-key)
 4. [Capturing MQTT (Notifications)](#capturing-tls-requests)
 
## Common Errors
### IgActionSpamError or feedback_required
Occurs as the name suggests after a large amount of requests (in a short amount of time).

**Fix:** Add a delay between the requests and/or use proxies for multiple accounts.

### IgCheckpointError or challenge_required
See [this](https://github.com/dilame/instagram-private-api/blob/master/examples/checkpoint.example.ts).
 
### login_required
This is thrown whenever your session is invalid.
You can fix it by not loading the session/cookies. 
Most of the time you'll face another error afterwards.

## Capturing Endpoints

In order to capture endpoints you have to monitor the requests using a proxy.
Instagram itself prevents that as anyone could monitor your requests, so you'll have to modify the app.
Currently, [this](https://github.com/itsMoji/Instagram_SSL_Pinning) project by [itsMoji](https://github.com/itsMoji)
allows you to disable the certificate-pinning which effectively makes the app accept every certificate.

**Only use it in _your_ network as anyone with the certificate can then monitor your requests!**

#### Step by step guide
 The first steps are just for setting up the apk. You can also use [these](https://github.com/itsMoji/Instagram_SSL_Pinning#instagram-ssl-pinning) instructions.

 1. **Install** either the patched apk provided by itsMoji [here](https://github.com/itsMoji/Instagram_SSL_Pinning/tree/master/non-root)
    **or** manually patch the apk (requires root access) 
    by following [these](https://github.com/itsMoji/Instagram_SSL_Pinning#root-method) instructions.
 2. **Install** a http proxy on your host machine.
     - Currently, the only proxy able to decrypt **TLS  1.3** is [Burp 1.7.x](https://portswigger.net/burp/releasesarchive/community)
     (use version 1.7 although it's outdated, 2.x **won't work**) with [Java 11 or above](https://www.oracle.com/technetwork/java/javase/downloads/index.html).
 3. **Configure** your proxy to decrypt TLS 1.3 and **export** the *root certificate* to the phone/emulator.
 4. **Capture** the requests.
 
#### General Infos

- A request looking like `signed_body={HEX}.{Request}&ig_sig_key_version=4` has to be signed.
 
## Reading the Signature Key

The signature key is used to sign requests.

#### Step by step guide

 1. [Setup Instagram on your phone like this](#capturing-endpoints)
 2. Install frida on your [device](https://www.frida.re/docs/android/) and [host machine](https://www.frida.re/docs/installation/).
 3. Start the frida-server on your device
 4. Connect to frida and the `com.instagram.android` process (using an emulator e.g. run `frida -U -n com.instagram.android`)
 5. Run ``` 
    fscrambler = Module.findExportByName("libstrings.so","_ZN9Scrambler9getStringESs");
    Interceptor.attach(ptr(fscrambler), {
       onLeave: function (retval) {
      send(Memory.readCString(retval));
       }
    });```
 6. Force a signed request inside the app by for example liking an image.
 7. You should now see `message: {'type': 'send', 'payload': '{SIGNATURE_KEY}'} data: none`


## Capturing TLS Requests

MQTT and FBNS are currently not implemented in the main library as they're not ready.
You can see the current development [here](https://github.com/dilame/instagram-private-api/issues/845).
They are built using MQTT (v3 and for FBNS a custom implementation of v3) and [Thrift](https://thrift.apache.org/)
You'll probably have to use a Hex Editor for that.

Currently, the only way of capturing these packets is using another proxy.

#### Step by step guide

If you are using Burp, **only** enable the proxy on `127.0.0.1`.

 1. [Setup Instagram on your phone like this](#capturing-endpoints)
 2. **Install** [Charles](https://www.charlesproxy.com/download/) (the test version only supports 30min per session, so save your results in another editor).
 3. **Configure** Charles as a **SOCKS** proxy (*Proxy* > *Proxy Settings...* > *Enable SOCKS Proxy*).
 4. **Export and install** the certificate (*Help* > *SSL Proxying* > *Install certificate on a Mobile Device or Remote Browser*).
 5. **Enable** SSL proxying for the domains `mqtt-mini.facebook.com:* and edge-mqtt.facebook.com:*` (*Proxy* > *SSL Proxying Settings...*).
 6. (optional) forward HTTP Packets to Burp (Charles only decrypts TLS 1.2):
    * Go to *Proxy* > *External proxy settings...*, enable it and forward HTTP and HTTPS to `127.0.0.1:{BURP_PORT}`. 
    * See your HTTP(S) requests in Burp.