#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <sys/ioctl.h>
#include <linux/sockios.h>


#define HOST "127.0.0.1"
#define PORT 1111


int main (int argc, char **argv)
{
	char *buf;
	int bufsiz;
	int sd, len, err;
	int sndbufsiz, used;
	int count = 0;
	int i;
	struct sockaddr_in sa;

	if(argc == 2) {
		bufsiz = atoi(argv[1]);
	} else {
		bufsiz = BUFSIZ;
	}
	printf("Allocating %d bytes for write buffer.\n", bufsiz);
	buf = malloc(bufsiz);
	if(!buf) {
		perror("malloc");
		exit(1);
	}

	sd = socket(AF_INET, SOCK_STREAM, 0);
	if(sd < 0) {
		perror("socket");
		exit(1);
	}

	memset(&sa, 0, sizeof(sa));
	sa.sin_family = AF_INET;
	sa.sin_addr.s_addr = htonl(INADDR_ANY);
	sa.sin_port = htons(0);

	err = bind(sd, (struct sockaddr*)&sa, sizeof(sa));
	if(err < 0) {
		perror("bind");
		exit(1);
	}

	memset(&sa, 0, sizeof(sa));
	sa.sin_family = AF_INET;
	sa.sin_port = htons(PORT);
	if(!inet_aton(HOST, &sa.sin_addr)) {
		printf("bad address\n");
		exit(1);
	}

	err = connect(sd, (struct sockaddr *)&sa, sizeof(sa));
	if(err < 0) {
		perror("connect");
		exit(1);
	}

	// give the read socket time to collect buffer sizes
	// start hitting it with data.
	sleep(1);

	for(i=0;;i++) {
		len = sizeof(sndbufsiz);
		err = getsockopt(sd, SOL_SOCKET, SO_SNDBUF, &sndbufsiz, &len);
		if(err < 0) {
			perror("getsockopt");
			exit(1);
		}

		err = ioctl(sd, SIOCOUTQ, &used);
		if(err < 0) {
			perror("ioctl SIOCOUTQ");
			exit(1);
		}

		len = write(sd, buf, bufsiz);
		if(len < 0) {
			perror("write");	
		}
		if(len <= 0) {
			exit(0);
		}

		count += len;
		printf("%2i: SO_SNDBUF=%6d, SIOCOUTQ=%6d: %6d avail.  Wrote %d bytes, %d total.\n",
				i, sndbufsiz, used, sndbufsiz - used, len, count);
	}
}