#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 <arpa/inet.h>
#include <sys/select.h>
#include <errno.h>
#include <error.h>

extern int h_errno;

#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);
}

int main(int argc, char *argv[])
{
	struct sockaddr_in sAddr, klientAddr, klientAddrPing;
	int listensock;
	int sockPing;
	int listenSockPing;
	int sock_cli;
	int servPort;
	char buffer[25];
	int result;
	int nread;
	unsigned int klientAddrSize;
	struct timeval selectTimeout;
	fd_set listaSelect;
	long timeout = 3;
	int probyNazwiazaniaPing;

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

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

	listenSockPing = socket(PF_INET, SOCK_STREAM, 0);
	if (listenSockPing <0) {
		perror("soecket() Ping");
		exit(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("bind() main");
		exit(1);
	}

	sAddr.sin_port = htons(servPort + 1);
	result = bind(listenSockPing, (struct sockaddr *) &sAddr, sizeof(sAddr));
	if (result < 0) {
		perror("bind() ping");
		exit(1);
	}

	result = listen(listensock, 5);
	if (result < 0) {
		perror("listen() main");
		exit(1);
	}
	result = listen(listenSockPing, 5);
	if (result < 0) {
		perror("listen() ping");
		exit(1);
	}
	klientAddrSize = sizeof(klientAddr);

	while (1) {
		sock_cli = accept(listensock, (struct sockaddr *) &klientAddr, &klientAddrSize);
		if (sock_cli < 0) {
			perror("accept() main");
			exit(1);
		}

		printf("DEBUG: klient %s:%i probuje sie do mnie dobic\n", inet_ntoa(klientAddr.sin_addr), ntohs(klientAddr.sin_port));
		probyNazwiazaniaPing = 0;
		while (1)
		{
			FD_ZERO(&listaSelect);
			FD_SET(listenSockPing, &listaSelect);

			selectTimeout.tv_sec = timeout;
			selectTimeout.tv_usec = 0;

			errno = (int) NULL;
			result = select(FD_SETSIZE, &listaSelect, NULL, NULL, &selectTimeout);
			if (result == -1)
			{
				perror("select()");
				break;
			}

			if (FD_ISSET(listenSockPing, &listaSelect)) {
				sockPing = accept(listenSockPing, (struct sockaddr *) &klientAddrPing, &klientAddrSize);
				if (sockPing < 0) {
					perror("accept() ping");
					exit(1);
				}
				printf("DEBUG: klient %s:%i probuje nawiazac polaczenie ping\n", inet_ntoa(klientAddrPing.sin_addr), ntohs(klientAddrPing.sin_port));
				if (klientAddrPing.sin_addr.s_addr != klientAddr.sin_addr.s_addr)
				{
					printf("DEBUG: powinienem dostac ping od %s\n", inet_ntoa(klientAddr.sin_addr));
					printf("DEBUG: dostalem od %s\n", inet_ntoa(klientAddrPing.sin_addr));
					if (probyNazwiazaniaPing == 3)
					{
						printf("DEBUG: przekroczono limit nawiazania polaczen ping\n");
						break;
					}
					printf("DEBUG: dostalem polaczenie ping od innego klienta, probuje jeszcze raz\n");

					errno = (int)NULL;
					result = close(sockPing);
					if (result == -1)
					{
						perror("close() bad ping");
					}
				} else {
					break;
				}
			} else {
				if (probyNazwiazaniaPing == 3)
				{
					printf("DEBUG: klient nie probowal nawiazac polaczenia ping\n");
					break;
				}
			}
			probyNazwiazaniaPing++;
		}
		if (probyNazwiazaniaPing == 3) break;

		printf("[+] Obsluguje klienta %s:%i\n", inet_ntoa(klientAddr.sin_addr), ntohs(klientAddr.sin_port));
		while (1)
		{
			FD_ZERO(&listaSelect);
			FD_SET(sockPing, &listaSelect);
			FD_SET(sock_cli, &listaSelect);

			selectTimeout.tv_sec = timeout;
			selectTimeout.tv_usec = 0;

			errno = (int) NULL;
			result = select(FD_SETSIZE, &listaSelect, NULL, NULL, &selectTimeout);
			if (result == -1)
			{
				perror("select()");
				break;
			}

			if (FD_ISSET(sock_cli, &listaSelect))
			{
				nread = read(sock_cli, buffer, MAXBUF-1);
				if (nread < 2)
					break;
				buffer[nread] = '\0';
				fprintf(stdout,"%s", buffer);
				write(sock_cli, buffer, nread);
			} else if (FD_ISSET(sockPing, &listaSelect)) {
				printf("DEBUG: otrzymalem ping, wysylam pong\n");
				errno = (int) NULL;
				result = read(sockPing, buffer, sizeof(buffer));
				if (result == -1)
				{
					perror("read() ping");
				}
				errno = (int) NULL;
				result = write(sockPing, buffer, 1);
				if (result == -1)
				{
					perror("write() pong");
				}
			}
		}
		printf("[-] Zakonczylem obsluge klienta.\n");
		close(sock_cli);
	}
	return 0;
}