owo.c

#define SRV_IP "127.0.0.1"

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

#define BUFLEN 512
#define NPACK 50
#define PORT 9930
#define BUF_SIZE 1000

#define SLOW_START 1
#define C_AVOID 2
#define FAST_RECOV 3

/* diep(), #includes and #defines like in the server */

struct sockaddr_in initial() {
	struct sockaddr_in si_other;

	memset((char *) &si_other, 0, sizeof(si_other));
	si_other.sin_family = AF_INET;
	si_other.sin_port = htons(PORT);
	if (inet_aton(SRV_IP, &si_other.sin_addr) == 0) {
		fprintf(stderr, "inet_aton() failed\n");
		return si_other;
	}

	return si_other;
}


int connect_socket(void) {
	int s;

	if ((s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1)
		perror("socket");

	return s;
}

void close_socket(int s) {
	close(s);
}

void print_cwnd(int cwnd) {
	printf("CWND = %d\n", cwnd);
}

void print_duplicate() {
	printf("3 duplicate ack\n");
}

void print_timeout() {
	printf("Time out\n");
}

int main(void) {
	struct sockaddr_in si_other, recv_ip;
	int s, i, slen = sizeof(si_other), rlen = sizeof(recv_ip);
	char buf[BUFLEN];

	struct timeval tv;
	fd_set readfds;

	si_other = initial();
	s = connect_socket();

	int send_buffer[NPACK + 1];
	int cwnd = 1;
	double cwnd_double = 1.0;
	int lastByteSent = 0;
	int lastByteAcked = 0;
	int ssthresh = 10;

	int pre_acked;
	int acked = 0;
	int duplicate_ack = 0;

	int state = SLOW_START;

	for (i = 0; i < NPACK + 1; i++) {
		send_buffer[i] = i;
	}

	/* Insert your codes below */
	memset(buf, 0, BUFLEN);

	ssthresh = 10;
	duplicate_ack = 0;
	cwnd = 1;
	cwnd_double = 1;
	int cwnd_count = 0;
	bool lose = true;
	while (lastByteSent <= NPACK) {
		memset(buf, 0, BUFLEN);
		sprintf(buf, "%d", send_buffer[lastByteSent]);
		sendto(s, buf, BUFLEN, 0, (struct sockaddr*) &si_other, (socklen_t) slen);

		// Set Timeout {
		tv.tv_sec = 1;
		tv.tv_usec = 0;
		FD_ZERO(&readfds);
		FD_SET(s, &readfds);
		select(s + 1, &readfds, NULL, NULL, &tv);
		// } Set Timeout

		// if (lastByteSent == 3 && lose) {lastByteSent += 1;lose=!lose;}
		// printf("\n\nsend=%s\n", buf);
		switch (state) {
		case SLOW_START:
			if (!FD_ISSET(s, &readfds)) {
				print_timeout();
				ssthresh = int(cwnd / 2);
				cwnd = 1;
				duplicate_ack = 0;
			}
			else {
				recvfrom(s, buf, BUFLEN, 0, (struct sockaddr*) &recv_ip, (socklen_t*) &rlen);
				int ack = atoi(buf);
				// printf("(SLOW_START)ack=%s\n", buf);
				if (ack == pre_acked) {
					duplicate_ack++;
					if (duplicate_ack == 3 ) {
						print_duplicate();
						lastByteSent-=3;
						ssthresh = int(cwnd / 2);
						state = FAST_RECOV;
						continue;
					}
				}
				else {
					cwnd += 1;
					duplicate_ack = 0;
					print_cwnd(int(cwnd));
				}
				pre_acked = ack;
				++lastByteSent;
			}
			if (cwnd >= ssthresh) {
				state = C_AVOID;
				cwnd_count = 0;
			}
			break;
		case C_AVOID:
			if (!FD_ISSET(s, &readfds)) {
				print_timeout();
				ssthresh = int(cwnd / 2);
				cwnd = 1;
				duplicate_ack = 0;
				state = SLOW_START;
			}
			else {
				recvfrom(s, buf, BUFLEN, 0, (struct sockaddr*) &recv_ip, (socklen_t*) &rlen);
				int ack = atoi(buf);
				// printf("(C_AVOID)ack=%s\n", buf);
				if (ack == pre_acked) {
					duplicate_ack++;
					if (duplicate_ack == 3) {
						print_duplicate();
						ssthresh = int(cwnd / 2);
						cwnd = ssthresh +3;
						lastByteSent-=3;
						state = FAST_RECOV;
						continue;
					}
				}
				else {
					cwnd_count++;
					if(cwnd_count >= cwnd){
						cwnd++;
						cwnd_count=0;
					}
					duplicate_ack = 0;
					print_cwnd(int(cwnd));
				}
				++lastByteSent;
				pre_acked = ack;
			}
			break;
		case FAST_RECOV:
			if (!FD_ISSET(s, &readfds)) {
				print_timeout();
				ssthresh = int(cwnd / 2);
				cwnd = 1;
				duplicate_ack = 0;
				state = SLOW_START;
			}
			else {
				recvfrom(s, buf, BUFLEN, 0, (struct sockaddr*) &recv_ip, (socklen_t*) &rlen);
				int ack = atoi(buf);
				// printf("(FAST_RECOV)ack=%s\n", buf);
				if (ack == pre_acked) {
					cwnd += 1;
				}
				else {
					cwnd = ssthresh;
					duplicate_ack = 0;
					state = C_AVOID;
					cwnd_count = 0;
					++lastByteSent;
					print_cwnd(int(cwnd));
				}
				pre_acked = ack;
				++lastByteSent;
			}
			break;
		}
		// printf("duplicate_ack=%d\n", duplicate_ack);
	}
	/* Insert your codes above */


	close_socket(s);
	return 0;
}