/*
 * discard.c
 * A simple discard server.
 *
 * Copyright 2003 John Heffner.
 */

#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/poll.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/param.h>
#include <netinet/in.h>

#if 0
#define RATELIMIT
#define RATE		100000	/* bytes/sec */
#define WAIT_TIME	(1000000/HZ-1)
#define READ_SIZE	(RATE/HZ)
#else
#define READ_SIZE	(1024*1024)
#endif

void child_handler(int sig)
{
	int status;
	
	wait(&status);
}

int main(int argc, char *argv[])
{
	int port = 9000;
	int lfd;
	struct sockaddr_in laddr;
	int newfd;
	struct sockaddr_in newaddr;
	int pid;
	socklen_t len;
	
	if (argc > 2) {
		fprintf(stderr, "usage: discard [port]\n");
		exit(1);
	}
	if (argc == 2) {
		if (sscanf(argv[1], "%d", &port) != 1 || port < 0 || port > 65535) {
			fprintf(stderr, "discard: error: not a port number\n");
			exit(1);
		}
	}
	
	if (signal(SIGCHLD, child_handler) == SIG_ERR) {
		perror("signal");
		exit(1);
	}
	
	memset(&laddr, 0, sizeof (laddr));
	laddr.sin_family = AF_INET;
	laddr.sin_port = htons(port);
	laddr.sin_addr.s_addr = INADDR_ANY;
	
	if ((lfd = socket(PF_INET, SOCK_STREAM, 0)) < 0) {
		perror("socket");
		exit(1);
	}
	if (bind(lfd, (struct sockaddr *)&laddr, sizeof (laddr)) != 0) {
		perror("bind");
		exit(1);
	}
	if (listen(lfd, 5) != 0) {
		perror("listen");
		exit(1);
	}
	
	for (;;) {
		if ((newfd = accept(lfd, (struct sockaddr *)&newaddr, &len)) < 0) {
			if (errno == EINTR)
				continue;
			perror("accept");
			exit(1);
		}
		
		if ((pid = fork()) < 0) {
			perror("fork");
			exit(1);
		} else if (pid == 0) {
			int n;
			char buf[READ_SIZE];
			int64_t data_rcvd = 0;
			struct timeval stime, etime;
			float time;
			
			gettimeofday(&stime, NULL);
			while ((n = read(newfd, buf, READ_SIZE)) > 0) {
				data_rcvd += n;
#ifdef RATELIMIT
				usleep(WAIT_TIME);
#endif
			}
 			gettimeofday(&etime, NULL);
			close(newfd);
			
			time = (float)(1000000*(etime.tv_sec - stime.tv_sec) + etime.tv_usec - stime.tv_usec) / 1000000.0;
			printf("Received %lld bytes in %f seconds\n", (long long)data_rcvd, time);
			printf("Throughput: %d B/s\n", (int)((float)data_rcvd / time));
			
			exit(0);
		}
		
		close(newfd);
	}
	
	return 1;
}