meow.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>
#include <pthread.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 (pre_acked <= NPACK) {
		printf("===================\n");
		// initial
		if(lastByteSent == 0){
			memset(buf, 0, BUFLEN);
			sprintf(buf, "%d", send_buffer[lastByteSent]);
			sendto(s, buf, BUFLEN, 0, (struct sockaddr*) &si_other, (socklen_t) slen);
			printf("send=%s\n", buf);
		}

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


		if (!FD_ISSET(s, &readfds)) {
			print_timeout();
			ssthresh = int(cwnd / 2);
			cwnd = 1;
			duplicate_ack = 0;
			state = SLOW_START;

			// fast retransmit
			memset(buf, 0, BUFLEN);
			sprintf(buf, "%d", send_buffer[acked]);
			sendto(s, buf, BUFLEN, 0, (struct sockaddr*) &si_other, (socklen_t) slen);
			// printf("fast retransmit=%d\n", send_buffer[acked]);
			continue;
		}


		else {
			recvfrom(s, buf, BUFLEN, 0, (struct sockaddr*) &recv_ip, (socklen_t*) &rlen);
			acked = atoi(buf);
			if (pre_acked == acked) {
				duplicate_ack++;
				if (duplicate_ack == 3) {
					print_duplicate();
					ssthresh = cwnd / 2;
					cwnd = ssthresh + 3;
					state = FAST_RECOV;

					// fast retransmit
					memset(buf, 0, BUFLEN);
					sprintf(buf, "%d", send_buffer[acked]);
					sendto(s, buf, BUFLEN, 0, (struct sockaddr*) &si_other, (socklen_t) slen);
					// printf("fast retransmit=%d\n", send_buffer[acked]);
					continue;

				}
				else {
					print_cwnd(cwnd);
					continue;
				}
			}

			else {
				pre_acked = acked;
				duplicate_ack = 0;
				if (state == SLOW_START) {
					printf("(SLOW_START)ack=%s\n", buf);
					cwnd++;
					if (cwnd >= ssthresh) {
						state = C_AVOID;
						cwnd_count = 0;
					}
				}
				else if (state == C_AVOID) {
					printf("(C_AVOID)ack=%s\n", buf);
					cwnd_count++;
					if (cwnd_count >= cwnd) {
						cwnd++;
						cwnd_count = 0;
					}
					duplicate_ack = 0;
				}
				else if (state == FAST_RECOV) {
					printf("(FAST_RECOV)ack=%s\n", buf);
					cwnd = ssthresh;
					state = C_AVOID;
					duplicate_ack = 0;
				}

				print_cwnd(cwnd);
			}
		}

		int count = 0;
		for (int i = lastByteSent + 1; i < pre_acked + cwnd; i++) {
			memset(buf, 0, BUFLEN);
			sprintf(buf, "%d", send_buffer[i]);
			sendto(s, buf, BUFLEN, 0, (struct sockaddr*) &si_other, (socklen_t) slen);
			// printf("send=%s\n", buf);
			++count;
		}

		lastByteSent += count;
		// printf("duplicate_ack=%d\n", duplicate_ack);
	}
	/* Insert your codes above */


	close_socket(s);
	return 0;
}