Thread: Question about sending binary data over socket

Hi.

I`m working on an application which reads a file from the disk, and sends it`s content over socket to a browser. The problem is that when the application starts sending the data, the browser shows the waiting for data icon for a while, and then stops with the no data received message. The function is the following:

Code:

void stream(int clientDescriptor, char *path)
{
	FILE *fp 			= NULL;
	char *fileContent 	        = NULL;
	long fileSize		= 0;
	int i				= 0;

	fp 		= fs_openFile(path, "rb");
	fileSize	= fs_getFileSize(fp);
	fileContent	= fs_getFileByPointer(fp);

	for (i=0;i<fileSize;i++)
	{
printf("%c",fileContent[i]);
		write(clientDescriptor, fileContent[i], 1);
	}
}

The printf("%c",fileContent[i]); part is working fine, it prints the whole content of the file to the screen, but the same fileContent[i] doesn`t arrive to the browser, or maybe the browser waits for some extra character...

I know there are many examples on the internet, but none of those worked for me. Maybe you can help me.


Thank you.

Your compiler should be complaining about that code. Make sure you have the warnings turned up and make sure you get rid of all of them. Those warnings are the compiler telling you you're probably/definitely doing something wrong.

Originally Posted by man 2 write

ssize_t write(int fd, const void *buf, size_t count);

Look at the type write() expects for buf. It's a void *. That void * can take a pointer to anything, including a char *, but you're sending it fileContent[i], which is just a plain old char. You would need to call it like:

Code:

write(clientDescriptor, &fileContent[i], 1);

Add that ampersand to get an address (make it a char *). You also need to check the return value of all your file and network IO functions. Read the docs on write for details. If it fails, print a sensible error message by using the perror function.

That worked.

Thank you very much.

Hmm...I'm not a HTTP expert, so you would have to consult the RFC for more details on whether you're talking HTTP correctly. Since it "works in Gnump3d", I'm guessing it's not the header content, but rather your socket. I also couldn't tell, with that limited sample of code, which of a myriad of problems you could be experiencing. Are you sure you're talking TCP, not UDP? Are you on the right port (probably 80)? Are you sure you got the socket set up correctly? I see you're still not checking the return value of your write calls (and probably not the socket creation/setup calls either). You need to check ever single IO call for error. For all I know, you didn't even set up the socket right and you aren't sending the headers anywhere. When you do that and come back with a sufficient code sample and have shown that you attempt to check for, catch and process errors with your network and file handling code, then I will help you more.