#include <string.h>
#include <sys/socket.h>  /* For struct sockaddr, socket, accept, listen, bind */
#include <netinet/in.h>  /* For struct sockaddr_in */
#include <arpa/inet.h>   /* For htons, htonl, inet_pton */
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>       /* For errno */
#include <stdint.h>
#include <unistd.h>      /* For close, read, write */

int main (int argc, char * argv []) {
    const char * host = "127.0.0.1";
    uint16_t port = 12345;
    switch (argc) {
    case 3:
	port = strtoul(argv[2], NULL, 10);
    case 2:
	host = argv[1];
    }
    struct sockaddr_in addr;
    addr.sin_family = AF_INET;
    /* need to set addr.sin_addr */
    if (!inet_pton(AF_INET, host, &addr.sin_addr)) {
	perror("could not determine address");
	return EXIT_FAILURE;
    }
    /* need to set addr.sin_port */
    addr.sin_port = htons(port);

    int conn = socket(AF_INET, SOCK_STREAM, 0);
    if (conn < 0) {
	perror("could not create socket");
	return EXIT_FAILURE;
    }

    if (connect(conn, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
	perror("could not connect");
	close(conn);
	return EXIT_FAILURE;
    }
    const char * message = "Ciao!\n";
    size_t len = strlen(message);
    size_t written = 0;
    while (written < len) {
	/* write to the socket object */
	ssize_t w_res = write(conn, message + written, len - written);
	if (w_res < 0) {
	    perror("could not write to socket");
	    close(conn);
	    return EXIT_FAILURE;
	}
	written += w_res;
    }
    close(conn);
}