control.c

#include <assert.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <arpa/inet.h>

#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/types.h>

#include <netinet/in.h>
#include <netinet/tcp.h>

#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>


#include <netinet/in.h>

#include "control.h"
#include "utils.h"

int setup_control_channel(oflops_context *ctx)
{
	struct sockaddr_in sin;
	struct sockaddr_in *sinptr;
	char buf[BUFLEN];
	unsigned int len;
	long flags;
	int one;
	struct ifreq ifr;


	fprintf(stderr, "Creating server socket...\n");
	ctx->listen_fd = socket( AF_INET, SOCK_STREAM, 0); //create genericl socket
	if(ctx->listen_fd == -1)
		perror_and_exit("Dying on socket",1);

	fprintf(stderr, "Setting SO_REUSE\n");
	one =1;

	/* in case this socket is in use and in active state then reuse it.
	   (In case the progrem was terminated but didn;t shutdown properly
	   it listening port )
	 */
	if(setsockopt(ctx->listen_fd,SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)))
		perror_and_exit("Dying on setsockopt(SO_REUSEADDR)\n",1);
	assert(ctx->channels[OFLOPS_CONTROL].dev);

	/*
	 * Get the name of the interface on which the socket was opened.  
	 */
	strncpy(ifr.ifr_name,ctx->channels[OFLOPS_CONTROL].dev,IFNAMSIZ);
	if( ioctl( ctx->listen_fd, SIOCGIFADDR, &ifr)  == -1 )
		perror_and_exit("ioctl() SIOCGIFADDR to dev",1);
	sinptr = (struct sockaddr_in *) & ifr.ifr_addr;	// convenience pointer


	sin.sin_family = AF_INET;
	sin.sin_addr =  sinptr->sin_addr;	// bind to the specific device
	sin.sin_port = htons(ctx->listen_port);
	fprintf(stderr, "Binding to port %d \n", ctx->listen_port);
	if(bind( ctx->listen_fd, (struct sockaddr *) &sin, sizeof(sin)))
		perror_and_exit("Dying on binding listen port",1);
	if(listen( ctx->listen_fd,16))
		perror_and_exit("Dying on listen",1);


	fprintf( stderr, "Waiting for a switch to connect...\n");
	len = sizeof(sin);
	if((ctx->control_fd=
			accept( ctx->listen_fd, (struct sockaddr *) &sin, &len)) == -1)
		perror_and_exit("accept",1);
	inet_ntop(AF_INET,&sin.sin_addr,buf,BUFLEN);
	fprintf( stderr, "Got connection from %s:%d \n",
			buf, htons(sin.sin_port));
	fprintf( stderr, "Setting control channel to non-blocking\n");
	flags = O_NONBLOCK;
	if(fcntl(ctx->control_fd, F_SETFL, flags))
		perror_and_exit("Dying on fcntl(control, O_NONBLOCK)",1);
    fprintf( stderr, "Turning off @&^$!@# Nagle algorithm on control channel\n");
    /*
     * TCP_NODELAY and TCP_CORK basically control packet "Nagling," 
     * or automatic concatenation of small packets into bigger frames performed 
     * by a Nagle algorithm.
     */
    if(setsockopt(ctx->control_fd, SOL_TCP, TCP_NODELAY, &one, sizeof(one)))
        perror_and_exit("Dying on setsockopt(tcp_nodelay",1);

    //setup pcap capturing on the control channel in order to get 
    //higher granularity timestamps. 
    
    
	
    return 0;

	

}