Socket Programming in C

TaiL · 07-15-2009, 11:26 AM

Trying to program a stop and wait network protocol in C which will send a packet in the form of a struct

Code:

struct MyHdr{
	unsigned char seq;  //sequence number
	unsigned char wndwsize;  //size of the send window
	unsigned char pcktsize;   //packet size
	data char[sizeof pcktsize];    //data array size of packetsize (-overhead)
};

I have been reading up on the send() and recv() classes but still don't have enough knowledge to know how to send a "packet" over. Can someone clarify how to do this with me?

Here's what I have been playing with

Code:

	

while(fread(buffer,1,64,in) !=0){
		struct MyHdr packet;
		
		resent =0;
		count++;
		
		packet.pcktsize = buffer;//copy buffer into our packet 64bytes
		packet.seq = count;
		packet.wndwsize = count;
		
		do
		{
		//something with a CRC
		//
		}

		send(sockfd,packet);

	}

Can I just send with the given socket and the packet? Also how would I receive it?

TaiL · 07-15-2009, 11:46 AM

can someone move this to the C programming forum?

MK27 · 07-15-2009, 01:03 PM

Quote:

Originally Posted by TaiL

I have been reading up on the send() and recv() classes but still don't have enough knowledge to know how to send a "packet" over. Can someone clarify how to do this with me?

They are not classes. They are functions.

Before you can do something special in the way that you want it, you may have to be able to do something normal and basic. So trying going through a simple socket/networking tutorial and write a simple client and server program or something. They use send and recv. Then you will have the understanding you need to proceed onto constructing, transmitting, and deconstructing packets.

Right now, you do not have this basic understanding, so there is not much that can be said, I think.

bithub · 07-16-2009, 09:14 AM

You do not need to worry about the header portion of the packet; this will be done for you. All you need to worry about is the packet payload (the data you are sending and receiving).

In other words, something like this is perfectly valid:

Code:

send(fd, "here is some data", 18, 0);

From your code, it's clear that you need to read the documentation on the send() function. You do not need to worry about CRCs, sequence numbers, or window sizes.

dash · 08-04-2009, 03:35 AM

Hi all,

Can anybody give me a guideline for writing a DHCP client using socket programming on Linux platform?

Any kind of help, suggestion of good books and links will be highly appreciated ...

Thanks and regards,
Dash

Maniraj Patri · 08-22-2009, 11:12 PM

what are netlink sockets. When and why they are used.

**Salem** · 08-23-2009, 12:19 AM

"me too" bumpers should start a new thread.

07-15-2009, 11:26 AM	#1
TaiL Registered User Join Date: Oct 2008 Posts: 66	Socket Programming in C Trying to program a stop and wait network protocol in C which will send a packet in the form of a struct Code: struct MyHdr{ unsigned char seq; //sequence number unsigned char wndwsize; //size of the send window unsigned char pcktsize; //packet size data char[sizeof pcktsize]; //data array size of packetsize (-overhead) }; I have been reading up on the send() and recv() classes but still don't have enough knowledge to know how to send a "packet" over. Can someone clarify how to do this with me? Here's what I have been playing with Code: while(fread(buffer,1,64,in) !=0){ struct MyHdr packet; resent =0; count++; packet.pcktsize = buffer;//copy buffer into our packet 64bytes packet.seq = count; packet.wndwsize = count; do { //something with a CRC // } send(sockfd,packet); } Can I just send with the given socket and the packet? Also how would I receive it?
TaiL is offline

07-15-2009, 11:46 AM	#2
TaiL Registered User Join Date: Oct 2008 Posts: 66	can someone move this to the C programming forum?
TaiL is offline

07-16-2009, 09:14 AM	#4
bithub Registered User Join Date: Sep 2004 Location: California Posts: 2,845	You do not need to worry about the header portion of the packet; this will be done for you. All you need to worry about is the packet payload (the data you are sending and receiving). In other words, something like this is perfectly valid: Code: send(fd, "here is some data", 18, 0); From your code, it's clear that you need to read the documentation on the send() function. You do not need to worry about CRCs, sequence numbers, or window sizes.
bithub is offline

08-04-2009, 03:35 AM	#5
dash Registered User Join Date: Aug 2009 Posts: 2	writing dhcp client using sockets Hi all, Can anybody give me a guideline for writing a DHCP client using socket programming on Linux platform? Any kind of help, suggestion of good books and links will be highly appreciated ... Thanks and regards, Dash
dash is offline

08-22-2009, 11:12 PM	#6
Maniraj Patri Registered User Join Date: Aug 2009 Posts: 1	netlink sockets.. what are netlink sockets. When and why they are used.
Maniraj Patri is offline

08-23-2009, 12:19 AM	#7
Salem and the hat of vanishing Join Date: Aug 2001 Location: The edge of the known universe Posts: 21,214	"me too" bumpers should start a new thread. __________________ If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut. Up to 8Mb PlusNet broadband from only £5.99 a month!
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