#include <unistd.h> // Per les crides a fitxer

#include <stdio.h>  // Per l'I/O de stdin/stdout

#include <errno.h>  // Pels errors de les crides a fitxer

#include <string.h> // Per strerror()

#include <stdlib.h> // Per abort()

#include <fcntl.h> // Per fcntl()

#include <netinet/in.h>

#include <arpa/inet.h>

#include <stdbool.h>

#include <signal.h>

#include <assert.h> // Per assert()

#include <sys/select.h> // Pel select()

#include "syslog.h"

/* Prototypes */

static void listen_tcp(const int port, const bool ipv6enabled);

static int listen_tcp_ipv6(int port);

static int listen_tcp_ipv4(int port);

static int accept_connection(int socket);

/* Returns 0 on success. Returns -1 on error. */

int init_tcp_server()

{

	int pid;

	int port;

	char service[MAX_STRING];

	enum {

		SUCCESS=0,

		ERROR=-1,

		DISABLED=-2

	} ret;

	/* Get the configuration */

	get_config(TCP_MANAGER, service, MAX_STRING);

	if (strncmp(service, "disabled", MAX_STRING) == 0)

		return DISABLED;

	/* Check the configuration */

	port = atoi(service);

	if (port < -65535 || port > 65535)

		return ERROR;

	/* Create the server process */

	pid = child_fork();

	if (pid == 0)

	{

		program_child_handler(SIG_DFL);

		/* Child */

		close(0);

		close(1);

		//close(2);

		if(port < 0)

		{

			listen_tcp(-port, true);

		} else

		{

			listen_tcp(port, false);

		}

		/* Should be Not reachable */

		exit(0);

	} else if (pid > 0)

	{

		/* Parent */

		fprintf(stderr, "Child forked (tcp server on port %i): %i\n",

			port, pid);

		ret = SUCCESS;

	} else

	{

		ret = ERROR;

	}

	return ret;

}

static void listen_tcp(const int port, const bool ipv6enabled)

{

	int socket_ipv6, socket_ipv4;

	fd_set listen_sockets;

	int result;

	int high_socket;

	socket_ipv4 = listen_tcp_ipv4(port);

	if (ipv6enabled)

		socket_ipv6 = listen_tcp_ipv6(port);

	/* Mirem quin és el socket més alt pel select() */

	high_socket = socket_ipv4;

	if (ipv6enabled && (high_socket < socket_ipv6) )

		high_socket = socket_ipv6;

	high_socket += 1;

	result = 0;

	while (result >= 0)

	{

		/* Establim els FDs que volem esperar al select() */

		FD_ZERO(&listen_sockets);

		if (ipv6enabled)

			FD_SET(socket_ipv6, &listen_sockets);

		FD_SET(socket_ipv4, &listen_sockets);

		result = select(high_socket, &listen_sockets, NULL, NULL,

			NULL);

		if (result == 0)

		{

			/* Això no hauria de passar, no tenim timeout fixat. */

			continue;

		}

		else if (result == -1 && errno != EINTR)

		{

			fprintf(stderr, "Error in select(): %s\n",

				strerror(errno));

			abort();

		}

		/* Algun FD té dades... */

		if (FD_ISSET(socket_ipv4, &listen_sockets))

		{

			accept_connection(socket_ipv4);

		}

		if (ipv6enabled && FD_ISSET(socket_ipv6, &listen_sockets))

		{

			accept_connection(socket_ipv6);

		}

	}

}

static int listen_tcp_ipv6(int port)

{

	int socket_ipv6;

	struct sockaddr_in6 source_ipv6;

	int result;

	int on=1;

	socket_ipv6 = socket(PF_INET6, SOCK_STREAM, 0);

	if (socket_ipv6 == -1)

	{

		fprintf(stderr, "IPv6 socket failed.\n");

		abort();

	}

	/* Fem que poguem reutilitzar l'adreça encara que no s'hagi acabat

	   el timeout després de tancar-se la connexió */

	if (setsockopt(socket_ipv6, SOL_SOCKET, SO_REUSEADDR,

	                         (char *)&on,sizeof(on)) < 0)

	{

		fprintf(stderr, "IPv6 setsockopt() failed: %s.\n",

			strerror(errno));

		abort();

	}

	/* No volem que aquest socket bloquegi. */

	if (fcntl(socket_ipv6, F_SETFL, O_NONBLOCK) == -1)

	{

		fprintf(stderr, "IPv6 fcntl() failed: %s.\n",

			strerror(errno));

		abort();

	}

	/* IPv6 listen address */

	memset(&source_ipv6, 0, sizeof(source_ipv6));

	source_ipv6.sin6_family = AF_INET6;

	source_ipv6.sin6_flowinfo = 0;

	source_ipv6.sin6_port = htons(port);

	source_ipv6.sin6_addr = in6addr_any;

	result = bind(socket_ipv6, (struct sockaddr *) &source_ipv6,

		sizeof(source_ipv6));

	assert(result == 0);

	result = listen(socket_ipv6, TCP_LISTEN_QUEUE);

	if (result != 0)

	{

		fprintf(stderr,"Error in listen() ipv6: %s\n", strerror(errno));

		abort();

	}

	return socket_ipv6;

}

static int listen_tcp_ipv4(int port)

{

	int socket_ipv4;

	struct sockaddr_in source_ipv4;

	int result;

	int on=1;

	socket_ipv4 = socket(PF_INET, SOCK_STREAM, 0);

	if (socket_ipv4 == -1)

	{

		fprintf(stderr, "IPv4 socket not supported.\n");

		abort();

	}

	/* Fem que poguem reutilitzar l'adreça encara que no s'hagi acabat

	   el timeout després de tancar-se la connexió */

	if (setsockopt(socket_ipv4, SOL_SOCKET, SO_REUSEADDR,

	                         (char *)&on,sizeof(on)) < 0)

	{

		fprintf(stderr, "IPv4 setsockopt() failed: %s.\n",

			strerror(errno));

		abort();

	}

	/* No volem que aquest socket bloquegi. */

	if (fcntl(socket_ipv4, F_SETFL, O_NONBLOCK) == -1)

	{

		fprintf(stderr, "IPv6 fcntl() failed: %s.\n",

			strerror(errno));

		abort();

	}

	/* IPv4 listen address */

	memset(&source_ipv4, 0, sizeof(source_ipv4));

	source_ipv4.sin_family = AF_INET;

	source_ipv4.sin_port = htons(port);

	source_ipv4.sin_addr.s_addr = htonl(INADDR_ANY);

	result = bind(socket_ipv4, (struct sockaddr *) &source_ipv4,

		sizeof(source_ipv4));

	assert(result == 0);

	result = listen(socket_ipv4, TCP_LISTEN_QUEUE);

	if (result != 0)

	{

		fprintf(stderr,"Error in listen() ipv4: %s\n", strerror(errno));

		abort();

	}

	return socket_ipv4;

}

static int accept_connection(int socket)

{

	int newsock, pid;

	newsock = accept(socket, NULL, NULL);

	if (newsock == -1)

		return 0;

	/* We don't use child_fork(), as it's only for the _main parent_ */

	pid = fork();

	if (pid == 0)

	{

		/* Child */

		close(socket);

		send(newsock, "hola\n", 5, 0);

		close(newsock);

		exit(0);

		/* Unreachable */

	} else if (pid > 0)

	{

		/* Parent */

		close(newsock);

	}

	else

		return -1;

	return 0;

}