#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <netdb.h>
#include <time.h>
#include <errno.h>
#include <fcntl.h>
#include <arpa/inet.h>
#include <signal.h>

extern int h_errno;
short int gotOOB = 0;

#define MAXBUF 80

void blad(char * message)
{
	fprintf(stderr, "%s\n", message);
	exit(1);
}

int isNumber(char * string)
{
	int i = 0;
	for (i = 0; string[i] != 0; ++i)
	{
		if (string[i] < '0' || string[i] > '9')
		{
			return 0;
		}
	}
	return 1;
}

int anyPort_to_int(char * string)
{
	FILE * potok;
	char buffer[MAXBUF];
	int readed;
	char * portStart;
	char * cp;

	if (isNumber(string))
	{
		portStart = string;
	} else {
		snprintf(buffer, sizeof(buffer), "getent services %s", string);
		potok = popen(buffer, "r");
		if (potok == NULL) blad("popen() error");
		if (feof(potok)) blad("can't find given port number");
		readed = fread(buffer, sizeof(char), sizeof(buffer), potok);
		if (ferror(potok)) blad("fread() error");
		if (readed == 0) blad("can't find given port number");
		buffer[readed - 1] = 0;

		for (cp = buffer; *cp != '/'; cp += sizeof(char))
		{
			if (*(cp - sizeof(char)) == ' ' && *cp >= '0' && *cp <= '9')
				portStart = cp;
		}
		cp = 0;
	}
	return atoi(portStart);
}

void handleSigUrg(int s)
{
	printf("[!] Otrzymalem sygnal URG\n");
	gotOOB = 1;
	return;
}

void handleSigAlarm(int s)
{
	printf("[!] Otrzymalem sygnal Alarm\n");
	return;
}

int main(int argc, char *argv[])
{
	struct sockaddr_in sAddr, klientAddr;
	int listensock;
	int sock_cli;
	int servPort;
	char buffer[25];
	int result;
	int nread;
	unsigned int klientAddrSize;
	int delay;
	struct sigaction sigactionUrg;
	struct sigaction sigactionAlarm;
	char c;

	if (argc != 2) {
		fprintf(stderr, "Uzycie: %s <Port>\n",argv[0]);
		exit(1);
	}

	listensock = socket(PF_INET, SOCK_STREAM, 0);
	if (listensock <0) {
		perror("serwer");
		exit(1);
	}
	servPort=anyPort_to_int(argv[1]);

	sAddr.sin_family = AF_INET;
	sAddr.sin_port = htons(servPort);
	sAddr.sin_addr.s_addr = INADDR_ANY;
	result = bind(listensock, (struct sockaddr *) &sAddr, sizeof(sAddr));
	if (result < 0) {
		perror("serwer");
		exit(1);
	}
	result = listen(listensock, 5);
	if (result < 0) {
		perror("serwer");
		exit(1);
	}
	klientAddrSize = sizeof(klientAddrSize);

	srand(time(NULL) * getpid());

	sigactionUrg.sa_handler = handleSigUrg;
	sigaction(SIGURG, &sigactionUrg, NULL);

	sigactionAlarm.sa_handler = handleSigAlarm;
	sigaction(SIGALRM, &sigactionAlarm, NULL);

	while (1) {

		sock_cli = accept(listensock, (struct sockaddr *) &klientAddr, &klientAddrSize);
		if (sock_cli < 0) {
			perror("accept()");
			exit(1);
		}
		printf("[+] Obsluguje klienta %s:%i\n", inet_ntoa(klientAddr.sin_addr), ntohs(klientAddr.sin_port));
		errno = (int) NULL;
		result = fcntl(sock_cli, F_SETOWN, (long) getpid());
		if (result == -1)
		{
			perror("fcntl()");
			exit(EXIT_FAILURE);
		}

		while (1)
		{
			if (gotOOB == 1)
			{
				gotOOB = 0;
				recv(sock_cli, &c, 1, MSG_OOB);
				if (c == 'I')
				{
					printf("DEBUG: otzymalem ping request i odpowiadam na niego\n");
					c = 'O'; /* pOng */
					send(sock_cli, &c, 1, MSG_OOB);
				} else if (c == 'O') {
					printf("DEBUG: otrzymalem odpowiedz na ping\n");
				} else {
					printf("DEBUG: otrzymalem nieznany rodzaj OOB\n");
				}
			}
			nread = read(sock_cli, buffer, MAXBUF-1);
			if (nread < 2)
				break;
			buffer[nread] = '\0';
			fprintf(stdout,"%s", buffer);
			delay = rand() % 20;
			printf("DEBUG: wprowadzam sztuczne opoznienie %i sekund\n", delay);
			while (delay != 0)
			{
				if ((delay = sleep(delay)) != 0)
				{
					printf("DEBUG: przerwano sleep(), wracam do sleep()\n");
				}
			}
			write(sock_cli, buffer, nread);
		}
		printf("[-] Zakonczylem obsluge klienta.\n");
		close(sock_cli);
	}
}