Simple stop wait transfer protocol

lib.h

#ifndef LIB
#define LIB

typedef struct {
  int type;
  int len;
  char payload[1400];
} msg;

void init(char* remote,int remote_port);
void set_local_port(int port);
void set_remote(char* ip, int port);
int send_message(const msg* m);
int recv_message(msg* r);
//msg* receive_message_timeout(int timeout);

#endif

recv.c

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include "lib.h"

#define HOST "127.0.0.1"
#define PORT 10001

#define FR_FILENAME 1
#define FR_DATA 2
#define FR_ACK 3

msg create_message(int type, char *data, int length) {
	msg m;
	m.len = length;
	m.type = type;
	memset(m.payload, 0, length);
	memcpy(m.payload, data, length);

	return m;
}

void send_ack() {
	msg t;
	t = create_message(FR_ACK, NULL, 0);
	send_message(&t);
}

int main(int argc,char** argv){
	msg r;
	init(HOST,PORT);
	int fd;
	int forever = 1;
	int ret;

	while (forever) {
		if (recv_message(&r)<0){
			perror("Receive message");
			return -1;
		}
		printf("[%s] Got msg with payload: %s %d\n", argv[0], r.payload, r.type);
		switch(r.type) {
			case FR_DATA:
				write(fd, r.payload, r.len);
				send_ack();
				break;
			case FR_FILENAME:
				fd = open(strcat(r.payload, ".out"), O_RDWR | O_CREAT | O_APPEND, 0666);
				send_ack();
				break;
			case FR_ACK:
				forever = 0;
				ret = close(fd);
				if (ret < 0){
					perror("Close file error");
				}
				break;
			default:
				break;
		}
	}

	return 0;
}

send.c

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "lib.h"

#define HOST "127.0.0.1"
#define PORT 10000

#define BUFSIZE 1400
#define FR_FILENAME 1
#define FR_DATA 2
#define FR_ACK 3

msg create_message(int type, char *data, int length) {
	msg m;
	m.len = length;
	m.type = type;
	memset(m.payload, 0, length);
	memcpy(m.payload, data, length);

	return m;
}

void send_ack() {
	msg t;
	t = create_message(FR_ACK, NULL, 0);
	send_message(&t);
}

void wait_ack() {
	msg r;
	recv_message(&r);
}

int main(int argc,char** argv){
	init(HOST,PORT);
	msg t;

	t = create_message(FR_FILENAME, argv[1], strlen(argv[1]));

	send_message(&t);

	wait_ack();

	int fd;
	int bytesRead;
	char buffer[BUFSIZE];

	fd = open(argv[1], O_RDONLY);

	if (fd < 0) perror("file error");

	while ((bytesRead = read(fd, buffer, BUFSIZE)) > 0) {
		t = create_message(FR_DATA, buffer, bytesRead);
		send_message(&t);
		wait_ack();
	}

	send_ack();

	return 0;
}