It is compiled in debug mode, the asserts aren't being erased during compilation, and my program just blocks on recvfrom. Edit: just a bit more info, I have the two computers connected on a dedicated switch, no outside interference.
I also have a second network card on my client computer that connects to the company network, which also works. I can ping both the outside Internet working and my server machine plus I can see the actual packets in Wiresharkbut you never know what might cause this problem. As it turns out my code is perfectly fine, as I thought it would be. There was a problem with the network setup itself.
For posterity, I had set up two static IP'd computers on their own hub, instead of using the built in DHCP server on the server machine to allocate the IP address for the other computer. Pretty localized for my problem but you never know.
Be sure that netmask is correct.
How are we doing? Please help us improve Stack Overflow. Take our short survey. Learn more. Asked 7 years, 6 months ago. Active 5 years, 7 months ago. Viewed 32k times. Is there any other hoop I have to jump through to receive an untargeted UDP broadcast? Blindy Blindy This code works for me after slight modification to make it compile with a C compile.
Possible the bind is binding to the wrong interface? What does netstat -an grep return on the client machine? Yeah it's supposed to work, but it doesn't for me.
Only connect and listen do that. But you do not need to open a port via listen in order to receive UDP broadcasts.
UDP socket programming in winsock
RemyLebeau Certainly bind opens a port. Have a look at netstat after you call it. I was referring to TCP when I mentioned that connect opens a port. Active Oldest Votes. To send and receive broadcast Be sure that netmask is correct. Fl0 Fl0 35 1 1 bronze badge. Why post this? You can see I've done exactly this in my original message from Sign up or log in Sign up using Google. Sign up using Facebook.Shows how to a use datagram UDP socket to send and receive data using the DatagramSocket and related classes in the Windows.
Note: This sample is part of a large collection of UWP feature samples. You can download this sample as a standalone ZIP file from docs. For more samples, see the Samples portal on the Windows Dev Center. The client component of the sample creates a UDP socket, uses the socket to send and receive data, and closes the socket.
The server component of the sample creates a UDP socket to listen for incoming network packets, receives incoming UDP packets from the client, sends data to the client, and closes the socket. If you are interested in developing an app that is always connected and always reachable using background network notifications in a UWP app, refer to the SocketActivityTrigger documentation.
This sample requires that network capabilities be set in the Package. These capabilities can be set in the app manifest using Microsoft Visual Studio. For more information on network capabilities, see How to set network capabilities.
Note Network communications using an IP loopback address cannot normally be used for interprocess communication between a Universal Windows Platform UWP app and a different process a different UWP app or a desktop app because this is restricted by network isolation. Network communication using an IP loopback address is allowed within the same process for communication purposes in a UWP app.
For more information, see How to set network capabilities. Networking Windows.
Sockets Windows. DataReader Windows. DataWriter SocketActivityTrigger. The next steps depend on whether you just want to deploy the sample or you want to both deploy and run it. Skip to content. Branch: master. Create new file Find file History. Latest commit. Latest commit 3ac8bb2 Mar 26, You signed in with another tab or window.
UDP Client Server using connect | C implementation
Reload to refresh your session. You signed out in another tab or window. Windows 10 Version - March Update. Mar 26, Dec 19, Learn more. These protocols are easy to use for downloading and uploading files and, in the case of HTTP, for sending requests to web servers and retrieving the results.
TCP is a reliable connection-oriented protocol that operates in terms of data streams transmitted between network nodes, and UDP is an unreliable connectionless protocol based on discrete packets sent between network nodes. Both can be used to create network client and server applications. The QFtp class works asynchronously. When we call a function such as get or putit returns immediately and the data transfer occurs when control passes back to Qt's event loop.
This ensures that the user interface remains responsive while FTP commands are executed. We will start with an example that shows how to retrieve a single file using get. The example is a console application called ftpget that downloads the remote file specified on the command line.
Let's begin with the main function:. The QCoreApplication::arguments function returns the command-line arguments as a QStringListwith the first item being the name the program was invoked as, and any Qt-specific arguments such as -style removed. The heart of the main function is the construction of the FtpGet object and the getFile call.
If the call succeeds, we let the event loop run until the download finishes. The class has a public function, getFilethat retrieves the file specified by a URL. The QUrl class provides a high-level interface for extracting the different parts of a URL, such as the file name, path, protocol, and port.
FtpGet has a private slot, ftpDonethat is called when the file transfer is completed, and a done signal that it emits when the file has been downloaded. The class also has two private variables: the ftp variable, of type QFtpwhich encapsulates the connection to an FTP server, and the file variable that is used for writing the downloaded file to disk.
In the constructor, we connect the QFtp::done bool signal to our ftpDone bool private slot. QFtp emits done bool when it has finished processing all requests. The bool parameter indicates whether an error occurred or not. The getFile function begins by checking the URL that was passed in. If a problem is encountered, the function prints an error message to cerr and returns false to indicate that the download failed.
Instead of forcing the user to make up a local file name, we try to create a sensible name using the URL itself, with a fallback of ftpget. If we fail to open the file, we print an error message and return false.
The url. Since no user name or password is given to the login function, an anonymous login is attempted. The FTP commands are queued and executed in Qt's event loop. The completion of all the commands is indicated by QFtp 's done bool signal, which we connected to ftpDone bool in the constructor.
Once the FTP commands have been executed, we close the file and emit our own done signal.I looking for example of sending and receving UDP Datagram broadcast message. I know, that I must use DatagramSocket class. Maybe someone has similar problem.
Thanks for ony help. Have you seen the DatagramSocket sample? Posting large amounts of code to the forum is not very helpful. If you would like assistance debugging your code please create a very small Visual Studio sample that reproduces the problem with the least amount of code possible only the code necessary to reproduce the problem, do not post your entire appzip it up please don't use RARupload it to your OneDrive and then post a link here.
Search related threads. Remove From My Forums. Asked by:. Windows and Windows phone apps. Archived Forums. Developing Universal Windows apps. Sign in to vote. Thursday, April 2, PM. Friday, April 3, PM.
Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I need to listen to a network broadcast coming over UDP.
I have tried following a few tutorials, but they seem to have left a few things out and dont have very detailed explanations, if any. The broadcast is coming in on How do I fix this error? Also, another thing I couldn't find was how to get the IP address of the sender out of the header. You don't bind to the broacast address; you bind to the machine's local IP or 0.
The broadcasts will reach the socket all the same. That's why it's a broadcast. Learn more. Asked 8 years, 5 months ago. Active 8 years, 5 months ago. Viewed 5k times.
Active Oldest Votes. Don't bind to To get the sender's address, use recvfrom and note the penultimate parameter. Seva Alekseyev Seva Alekseyev In Python, at least, 0. Binding to the local IP e. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. The Overflow How many jobs can be done at home? Featured on Meta. Community and Moderator guidelines for escalating issues via new response….
I'm trying to broadcast a current time once in 3 seconds and a current date once in 10 seconds. I'm spawning 3 threads: 1 listener, 1 for broadcasting time and 1 broadcasting date.
So your target address in the send function is compromised. Your laptop's network card address is stored in that variable. That's the reason why you just stop sending broadcasts. How are we doing? Please help us improve Stack Overflow. Take our short survey. Learn more. Asked 6 years ago. Active 6 years ago. Viewed 4k times. I have a udp listener on my desktop the same intranet with which I check my broadcasts.
If you have to warn that your code is quite long, then that's probably a sign that you should try and narrow it down a bit to the more relevant parts. If we need more parts of the code, we will ask you for it.
Active Oldest Votes. I suppose I got sloppy.
I often use Wireshark just to see what my programs are doing on the network. Usually I get better answer faster than in any forum. Probably you could do so. Note that len is an inout parameter also. Might want to reinitialise it. Therefore it works in the code excerpt.
There are other problems in the code like the strange value 'a' in the parameter to setsockoptthe impossibility to stop any thread, unused variables a in getDate and getTime. But these are not problem related. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password.
Programming udp sockets in C on Linux
The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. NET program listens for packets and parses to get the uptime of the server. As I have read, to send a regular UDP broadcast to the broadcast address, I simply have to send a packet to Is this right? Can I use the same port address? Are there any other necessities? I understand the fact that if my. NET program to read the header of the packet and see that it is almost the one I am looking for?
Regarding the broadcast IP addresses, both addresses are broadcast addresses but the limited broadcast address which is It is better to use the subnet-directed broadcast address For example: The server application will listen on a specific port number port Normally, the server will respond to each request using unicast message.
There will be no conflict as long as no application is listening on the same port number. However, if there is a conflict, then your signiture is depending on your protocol message format.
So, check the message format and reject the message if it does not follow the message format defined by your application protocol. For client applications, the received packet is unicast unless you have another design. So, no conflict at this side. If your. NET program listens for broadcast traffic, it will receive any and all broadcast traffic on the network sent on that port, including traffic not sent by your server.
You could put a "marker" in the payload of the broadcast messages sent by your server. This way, your. NET program could distinguish which ones it cares about. Beyond that, I would recommend using multicast instead of broadcast.
Broadcast traffic is usually restricted to hosts on the same subnet. In layman's terms, if you have a router in your network, a host on side A of the router will not see broadcast traffic sent by a host on side B and vice versa because the router "blocks" it.Understanding Unicast, Multicast, and Broadcast - CompTIA Network+ N10-005: 1.3
Routers will almost always forward multicast traffic if a host has joined the multicast group. Learn more. Network UDP broadcast design? Ask Question.
Asked 8 years, 10 months ago. Active 8 years, 10 months ago. Viewed 55k times. Matt Davis Andrei Zisu Andrei Zisu 3, 4 4 gold badges 17 17 silver badges 32 32 bronze badges. Active Oldest Votes.