I'm currently working on a ABAP Push Channel server to WebSocket client connection and I need the IP-address of the client in order to identify whether this client is the one I want to send the message to. In my scenario there could be multiple WebSocket connections.
Now there is the ssi_websocket_table table and the ssi_websocket_table_row row with the the field caller_ip, however this gives me the IP address of the DNS-Server of the network I'm connected to, and I expected the IP address of my local PC since the WebSocket-client is running on this machine.
Is there any other way to get the clients IP address from an active WebSocket connection in ABAP?
P.S. Looking at all the table entries, it shows the correct IP when using a different server configuration, as soon as I know why that's the case I will report back.
As pointed out by vwegert it makes no sense to use the IP to tell the WebSockets apart, I think it would probably be better to use an ID for each WebSocket connection instead.
You could get the IP from the WebSocket server context which gets the IP header apparently from the opening HTTP handshake for the connection:
DATA(lo_context) = i_context. " IF_APC_WSP_SERVER_CONTEXT type
DATA(lo_request) = lo_context->get_initial_request( ).
" initialize G_CONTEXT_ID_FIELD for PCP_SET_CONTEXT_FIELDS
DATA(lv_id) = lo_request->get_header_field( if_http_header_fields_sap=>remote_addr ).
the sample is taken from the SAP standard class CL_APC_WS_EXT_ABAP_ONLINE_COMM, ON_MESSAGE method.
Related
In my application, a client connects to the server at a given port and host.
Now, I want to know the port number that is opened at the client's end.
How can I get this information ?
Also, at the server end, can I also get the port number at which the client is connecting to ?
Basicaly, I want to send some extra information to the server when the client connects.. So, I will dump a file when a client is created with the file name as the port number of the client and at the server end, I will again try reading a file whose name is the port number of the client...
Now, I want to know the port number that is opened at the client's end.
Also, at the server end, can I also get the port number at which the client is connecting to ?
These questions seem to be the same to me. Unless you mean the port of the server, which you have to specify on both ends (and therefore already know).
Yes, you can get in your server the port of the connecting client along with the IP-address.
//boost::asio::ip::tcp::socket _socket;
_remoteAddress = _socket.remote_endpoint().address(); //You may call to_string() on it
_remotePort = _socket.remote_endpoint().port();
Basically I need to send data from Esp8266 to a server which is created using XAMPP on the laptop.
I have been using the following code on the ESP side
AT+CWJAP="dlink","password"
AT+CIPMUX=1
AT+CIPSTART=4,"TCP","192.168.0.105",80
AT+CIPSEND=4,6
123456 busy s...
AT+CIPCLOSE
My question is whether the IP address which i'm using is the correct IP for the server created using XAMPP? Do I need to send a GET request in order to send data? Do I need to make changes on the server side or just running the apache service is enough for my purpose?
The IP will be different in every network. I assume your network is set up with DHCP in which case the server might get different addresses every time.
There are mDNS libraries for ESP82666 that you can use to lookup the server by its local domain name (for example servername.local). Or you can configure the server to use a static IP.
Is it possible to route dns to different servers based on the protocol of the request without using a proxy server?
For example wss://example.com goes to 1 server and https://example.com goes to a different one.
In principle no, this is not possible. Although there are exceptions.
When you an application and request a network address, e.g. example.com the application will (typically) pass on a request to the OS to open a connection to that address.
Because the OS can only make a connection to an IP Address, the first thing it does is to make a DNS request to find out the address it can connect to. There is no mechanism at all, to tell that DNS request what protocol is being requested. At the point the OS makes the DNS request it is simply, 'What is the address for example.com' there is no space in the body of the message for more information.
In that sense it is not possible.
However there are a few services that use SRV records to find the server they need to connect to.
In these cases the application will say to the OS 'get me the SRV record for _somefancyservice.example.com' When it has that record, it will then send another request to the OS to open a connection the whatever it found in the SRV record.
So you could, in theory, write an application that performed the SRV record query first, and then opened a connection to whatever was returned.
I wrote a more detailed answer specifically about wss, which you may find interesting.
I have a ruby server based on TCPSocket (non-HTTP).
I have 2 different domains, both pointing with an A-Record to my servers IP Address (the same one). So, there are clients connecting to one of those domains.
Is it possible to tell which domain a client was connecting to?
I saw that this is possible in other protocols, but I'm not sure if this is based on manually added headers or really extracted from the basic tcp/ip connection. E.g. in PHP there is $_SERVER["HTTP_HOST"] which shows to which domain a client was connecting.
At the TCP socket level, the only things that are known are the source and destination IP addresses (and ports) of the connection. How the IP address was resolved via DNS is not possible to know at this layer. Even though HTTP works on top of TCP, HTTP servers have to look at the HTTP headers from the client to know which domain they are making a request to. (That's how the HTTP_HOST value gets filled in.)
One possible solution is to configure your server to have an additional IP address. This can be by assigning an additional IP address to the NIC or adding an additional NIC. Then have each domain use a different IP address. Otherwise, this is not possible and you may want to consider your application protocol on top of TCP to convey this information.
In order to receive datagrams through an UDP connection I have created an object of type UDPClient.
receivedNotificationSock = new UdpClient();
However once done and on using the receive method:
receivedHostNameBuffer=receivedNotificationSock.Receive(ref receivedNotificationIP);
I am getting an exception saying that I must call the bind method.
But there is no bind method in the UDPClient class.
Could You guys please provide me with the code if possible as to what should be done to overcome this exception.
You need I think to know some more about sockets.
All sockets possess a port number. First, you create a socket - which is almost useless on its own. It just floats there. But then you bind it - you assign it a port number. Now it's useful - now you can send and receive data on it.
Remember, all UDP communications are defined by the quad data set of the IP and port of the source and the IP and port of the destination. A freshly created socket doesn't have an IP address or port; binding gives it an IP address and port.
Unfortunately, I'm not a C# programmer, so I can't properly answer your question. But at least you know why it's important.
Pass the port number into the constructor of your UDP client.
receivedNotificationSock = new UdpClient(21000);
You may need to change firewall settings to allow the bind, though a popup window normally opens when you first run this on your dev machine.
For Socket proramming you need to know the sequence of syscalls you need to do on client side and on the server side.
If you are writting a client :
you open a socket with a socket call.
you then connect to the server port with a connect call
once connect is successful
then you send the request to the server using either a send or sendto or a write
which results in reception of data that you can read using a receive or read
On Server Side
you create a socket
bind it to a port
start listening on the socket for incoming connections from various clients using a listen.
There is a non blocking way of listening for connections as well with a select syscall.
Once the you establish a connection you can essentially read the request and start processing it.
Here's an example in C# that may be useful to you.
http://www.developerfusion.com/article/3918/socket-programming-in-c-part-1/