Extending networking/socket programming functionality of a qml project

[qcoderpro]

@SGaist

The device that runs the server shall update the record at noip to point to its own address.

1- So the server, using its code, should update the record at noip to point to its own address, and then client should connect to the hostname at noip. Hence this way both apps can establish a connection. Right?

2- But for the server to get access to noip and update its record and the client to get connected to the address provided by noip, we need an IP address. Right? I only see my PC's IP address and my hostname on noip!

3- Where's that IP address that will do the real job of the connection between the apps? I assume it should be my hostname! Wrong, please?

[SGaist]

1. Yes
2. As I already wrote, it's going to be the role of your server application to update the record at noip. You client will have the host name either hardcoded or as something that can be configured at runtime.
3. It's the IP address of the device that runs your server application.

[qcoderpro]

@SGaist

As I already wrote, it's going to be the role of your server application to update the record at noip.

I suppose it's a two-step task:

1- First the server (using its code) shall connect to noip. A simple connection piece of code (which is also used in my app) is: tcpSocket->connectToHost(ip, port.toInt()); So presumably an IP (and a port) is/are required for a connection. Therefore how should that server connect to noip, please?

2- The server then needs to update a record (of my hostname there, probably) so that the IP the server is running on will be set there. How does that update take place? I have no info of! :|

You client will have the host name either hardcoded or as something that can be configured at runtime.

3- OK, if we aim at hard coding, using what code should the client get access to the hostname, please?

[SGaist]

Are you realizing that your design is getting really complicated for not much benefit ?

1. you do realize that as soon as a mobile device (or any networked device for that matter) can access internet it already has an IP address ?
2. check with noip for a client library to do that.
3. Do you know what hardcoding a value means ? Also as a said, you can configure that value in a setting.

[qcoderpro]

Yes, I'm seeing it. I need to wait two days for a text reply.
But still have liked not to give up since all the stuff are completely new for me and are interesting.

1. you do realize that as soon as a mobile device (or any networked device for that matter) can access internet it already has an IP address ?

Yes, the client app itself has an IP address but the destination it wants to connect to (the noip site) should supposedly also have an IP address. I think you don't mean to use the IP address dedicated to the website for that connection!

2. check with noip for a client library to do that.

Will try that.

3. Do you know what hardcoding a value means ?

I think it means writing code. Know nothing more about that.

Also as a said, you can configure that value in a setting.

Setting? Setting of where?

[SGaist]

If you really need the noip address, then use QHostInfo.

Hardcoding means that you store some value within your code.

As for the settings, do you know what applications settings are ? Did you take a look at QSettings ?

[qcoderpro]

@SGaist
I'm not sure why QSettings is needed, since as far as I know our intention is not storing something on the device the app is running on and then recalling that thing when the app reruns.
Yes, using QHostInfo it's possible to connect to noip or even my hostname there, but the problem is how to update the record at noip/my hostname so that the server's IP will be set there. :(

As well as, I contacted noip and here's our talk:

• Suppose I send both applications to two of my friends each in a different city. One of them runs the server app on their mobile device (using the Internet through Wifi connection) and the other guy runs the client app on their mobile device, again, connected to a Wifi.
  What I, as the developer, can do is to modify the code for both apps to connect to my hostname "...ns.net". But the issue is, how is it possible for the server app to update a record there (on my hostname or so) to set its IP address in a way when the client app connects to my hostname, it can read the IP address of the server there and this way establish a connection, please?
  What section of your website should I check for that service and use it for that goal, please?

• Here at No-IP we simply resolve a hostname or domain to an IP address; no data is ever passed through us nor do we issue any IP addresses. Our services does not connect your hostname to other networks unless you configure your hostname there. Best practices are 1 hostname per network location. You will not be able to set a single hostname for 2 or more locations. If you wish to connect to your friends server app, the hostname must be configured on their network in an update client to send out the current public IP address from that network. An update client can be either a router, a DDNS capable device, or the DUC that can be downloaded from your No-IP account.

Still I'm confused. :(

[qcoderpro]

Can't anyone help me how to work the main issue out, please?
I believe the main issue is how to set the IP address of the server app on the noip website or my hostname to make it possible for the client app to get access to the server app and establish a connection.

[SGaist]

The main issue is that you currently do not understand properly how networking works.

As already written, your device automatically gets an IP address as soon as it is properly connected to a network be it WiFi, 4G/5G etc.

[qcoderpro]

@SGaist

I understand this. Suppose the server app is running on a device with IP: 123.456.789
To give that address to the client app, you suggested noip. OK, I signed up and added a hostname too and posted my last talk with them above. Now the main issue is giving that address to the client app or as you say: updating a record on noip. How to do that? This is my problem.

[SGaist]

The client uses the host name that's all from its side.

You server needs to implement the client part that updates the noip record. Take a look at their client to implement that.

[qcoderpro]

@SGaist

The client uses the host name that's all from its side.

The client connects to the hostname and gets its IP address. The IP of the hostname (I mean the one I added, "..dev.ddns.net") for example, is, 123.456.789, so the client now owns this address. Right?

You server needs to implement the client part that updates the noip record.

Does this mean that the server also needs to connect to the hostname above and gets that IP address!?

Take a look at their client to implement that.

Could you give me the address of that part, please?

[SGaist]

No, the server has the address the client application is interested in. It does not get it from noip. noip is a DNS service that associates a hostname with an IP address, nothing more.

As for writing code, see their documentation about that matter.

[qcoderpro]

@SGaist
Before writing the code, please let me understand the case completely.
The server has an IP address that the client is interested in (for establishing the connection). So how the client can know of that IP address?
The client can connect to hostname at noip and get the address of that hostname. But it's different from the server's IP! The server somehow should deliver its IP to the client for the connection. How is it done?

[SGaist]

The client just uses the hostname. That's all.

[qcoderpro]

@SGaist

1. So to sum it up: The client connects to my hostname which has been updated by the server to show its IP address and since this way the client can see the server's IP address it can connect to it. Right?
2. If the above question is right, is this page the one I should study on how to make the server app update the hostname's record with its IP?

[SGaist]

1. Yes
2. Looks like it yes.

[qcoderpro]

@SGaist

So in my server app there should be a line of code as an HTTP request, like this example (of that page):
http://username:password@dynupdate.no-ip.com/nic/update?hostname=mytest.example.com&myip=192.0.2.25

So if:
my username at noip is: coderdevqt@gmail.com
my password there is: passwordexample
and my hostname there is: coderdev.ddns.net

that HTTP request should be:
coderdevqt@gmail.com:passwordexample@dynupdate.no-ip.com/nic/update?hostname=coderdev.ddns.net
Right?

[SGaist]

Don't you think it would have been faster to just write and test the query ?

Also: https.

[qcoderpro]

@SGaist

I'm not sure how to make an HTTP request using QNetworkAccessManager by a single string. I tired this but neither of the qInfo() prints anything. The program also terminates at once! :|

 QNetworkAccessManager* manager = new QNetworkAccessManager(this);
    const QNetworkRequest request;
    const QByteArray data {"https://coderdevqt@gmail.com:passwordexample@dynupdate.no-ip.com/nic/update?hostname=coderdev.ddns.net"};
    manager->put(request,data);

    connect(manager, &QNetworkAccessManager::finished, [] {
        QNetworkReply* reply = nullptr;
        if(reply->error())
            qInfo() << "ERROR!: " + reply->errorString();
        else
            qInfo() << "Reply got back with no error!";

        reply->deleteLater();
    });