/*
 * Remote Laboratory Authentication Server
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * (c) 2012 Timothy Pearson
 * Raptor Engineering
 * http://www.raptorengineeringinc.com
 */

#include <stdlib.h>

#include "auth_conn.h"

/*
  The AuthSocket class provides a socket that is connected with a client.
  For every client that connects to the server, the server creates a new
  instance of this class.
*/
AuthSocket::AuthSocket(int sock, TQObject *parent, const char *name) :
	TQSocket( parent, name ) {

	iplocal = NULL;
	ipremote = NULL;
	searchpath = NULL;
	service = "remotefpga";
	localdomain = NULL;
	userdomain = NULL;
	conn = NULL;

	line = 0;
	connect(this, SIGNAL(connectionClosed()), SLOT(deleteLater()));
	connect(this, SIGNAL(connectionClosed()), SLOT(connectionClosedHandler()));
	setSocket( sock );
}

AuthSocket::~AuthSocket() {
	//
}

void AuthSocket::close() {
	TQSocket::close();
	connectionClosedHandler();
}

void AuthSocket::connectionClosedHandler() {
	printf("[DEBUG] Connection from %s closed\n\r", m_remoteHost.ascii());
}

int AuthSocket::initiateKerberosHandshake() {
	return authenticate_connection_with_kerberos(socket());
}

#define NET_SEC_BUF_SIZE (2048)

static int sasl_my_log(void *context __attribute__((unused)), int priority, const char *message) {
	const char *label;
	
	if (!message) {
		return SASL_BADPARAM;
	}
	
	switch (priority) {
		case SASL_LOG_ERR:
			label = "Error";
			break;
		case SASL_LOG_NOTE:
			label = "Info";
			break;
		default:
			label = "Other";
			break;
	}
	
	printf("[SASL %s] %s\n\r", label, message);
	
	return SASL_OK;
}

sasl_callback_t callbacks[] = {
	{SASL_CB_LOG, (sasl_callback_ft)&sasl_my_log, NULL},
	{SASL_CB_LIST_END, NULL, NULL}
};

void AuthSocket::free_conn(void) {
	if (conn) {
		sasl_dispose(&conn);
	}
}

void AuthSocket::send_sasl_data_to_network(const char *buffer, unsigned length, int netfd)
{
	char *buf;
	unsigned len, alloclen;
	int result;

	alloclen = ((length / 3) + 1) * 4 + 1;
	buf = (char*)malloc(alloclen);
	if (!buf) {
		printf("[ERROR] Unable to malloc()!\n\r");
		return;
	}

	result = sasl_encode64(buffer, length, buf, alloclen, &len);
	if (result != SASL_OK) {
		printf("[ERROR] Encoding data in base64 returned %s (%d)\n\r", sasl_errdetail(conn), result);
		return;
	}

	len = strlen(buf);
	buf[len] = '\n';
	buf[len+1] = 0;
	write(netfd, buf, len+1);

	free(buf);
}

unsigned int AuthSocket::get_sasl_data_from_network(char *buf) {
	unsigned int len;
	int result;

	len = 0;
	while (1) {
		tqApp->processEvents();
		if (state() != TQSocket::Connected) {
			return -1;
		}
		if (readBlock(buf+len, 1) > 0) {
			if (buf[len] == '\n') {
				buf[len] = 0;
				break;
			}
			if (buf[len] != '\r') {
				len++;
			}
		}
		if (len >= NET_SEC_BUF_SIZE) {
			break;
		}
	}

	len = strlen(buf);
	result = sasl_decode64(buf, (unsigned) strlen(buf), buf, NET_SEC_BUF_SIZE, &len);
	if (result != SASL_OK) {
		printf("[ERROR] Decoding data from base64 returned %s (%d)\n\r", sasl_errdetail(conn), result);
		return -1;
	}
	buf[len] = '\0';

	return len;
}

int AuthSocket::write_data_to_client(int fd, const char* readbuf, int cc) {
	int result = 0;
	unsigned int len;
	const char *data;

	result=sasl_encode(conn, readbuf, cc, &data, &len);
	if (result != SASL_OK) {
		printf("[ERROR] Encrypting data returned %s (%d)\n\r", sasl_errdetail(conn), result);
		return -1;
	}
	send_sasl_data_to_network(data, len, fd);

	return 0;
}

int AuthSocket::receive_data_from_client(char *buf, int netfd) {
	unsigned int recv_len;
	const char *recv_data;
	int result;
	int len;

	len = get_sasl_data_from_network(buf);
	if (len >= 0) {
		result=sasl_decode(conn, buf, len, &recv_data, &recv_len);
		if (result != SASL_OK) {
			printf("[ERROR] Decrypting data returned %s (%d)\n\r", sasl_errdetail(conn), result);
			return -1;
		}
		strncpy(buf, recv_data, NET_SEC_BUF_SIZE);
	}

	return 0;
 }

int AuthSocket::authenticate_connection_with_kerberos(int netfd) {
	char buf[NET_SEC_BUF_SIZE];
	int result = 0;
	int serverlast = 0;
	sasl_security_properties_t secprops;
	const char *ext_authid = NULL;
	unsigned int len;
	int count;
	const char *data;
	char user_authorized = 0;
	sasl_ssf_t *ssf;

	// FIXME
	// Initialize default data structures
	memset(&secprops, 0L, sizeof(secprops));
	secprops.maxbufsize = NET_SEC_BUF_SIZE;
	secprops.max_ssf = UINT_MAX;

	result = sasl_server_init(callbacks, "remotefpga");
	if (result != SASL_OK) {
		printf("[ERROR] Initializing libsasl returned %s (%d)\n\r", sasl_errdetail(conn), result);
		return -1;
	}

	result = sasl_server_new(service, localdomain, userdomain, iplocal, ipremote, NULL, serverlast, &conn);
	if (result != SASL_OK) {
		printf("[ERROR] Allocating sasl connection state returned %s (%d)\n\r", sasl_errdetail(conn), result);
		return -1;
	}

	result = sasl_setprop(conn, SASL_SEC_PROPS, &secprops);

	if (result != SASL_OK) {
		printf("[ERROR] Setting security properties returned %s (%d)\n\r", sasl_errdetail(conn), result);
		free_conn();
		return -1;
	}

	puts("[DEBUG] Generating client mechanism list...");
	result = sasl_listmech(conn, ext_authid, NULL, " ", NULL, &data, &len, &count);
	if (result != SASL_OK) {
		printf("[ERROR] Generating client mechanism list returned %s (%d)\n\r", sasl_errdetail(conn), result);
		free_conn();
		return -1;
	}

	printf("[DEBUG] Sending list of %d mechanism(s)\n\r", count);
	send_sasl_data_to_network(data, len, netfd);

	printf("[DEBUG] Waiting for client mechanism...\n\r");
	len = get_sasl_data_from_network(buf);
	if (strlen(buf) < len) {
		printf("[DEBUG] Initial response received (%d < %d) [%s]\n\r", strlen(buf), len, buf);
		// An initial response is present
		data = buf + strlen(buf) + 1;
		len = len - (unsigned) strlen(buf) - 1;
	}
	else {
		data = NULL;
		len = 0;
	}
	result = sasl_server_start(conn, buf, data, len, &data, &len);
	if (result != SASL_OK && result != SASL_CONTINUE) {
		printf("[ERROR] Starting SASL negotiation returned %s (%d)\n\r", sasl_errdetail(conn), result);
		free_conn();
		return -1;
	}

	while (result == SASL_CONTINUE) {
		if (data) {
			printf("[DEBUG] Sending response...\n\r");
			send_sasl_data_to_network(data, len, netfd);
		}
		else {
			printf("[ERROR] No data to send!\n\r");
			free_conn();
			return -1;
		}
		printf("[DEBUG] Waiting for client reply...\n\r");
		len = get_sasl_data_from_network(buf);
		data = NULL;
		result = sasl_server_step(conn, buf, len, &data, &len);
		if (result != SASL_OK && result != SASL_CONTINUE) {
			printf("[ERROR] Performing SASL negotiation returned %s (%d)\n\r", sasl_errdetail(conn), result);
			free_conn();
			return -1;
		}
	}
	printf("[DEBUG] Negotiation complete\n\r");

	if(serverlast && data) {
		printf("[DEBUG] Additional information needed to be sent\n\r");
		send_sasl_data_to_network(data, len, netfd);
	}

	result = sasl_getprop(conn, SASL_USERNAME, (const void **)&data);
	if (result != SASL_OK) {
		printf("[WARNING] Unable to determine authenticated username!\n\r");
	}
	else {
		printf("[DEBUG] Authenticated username: %s\n\r", data ? data : "(NULL)");
	}

	result = sasl_getprop(conn, SASL_DEFUSERREALM, (const void **)&data);
	if (result != SASL_OK) {
		printf("[WARNING] Unable to determine authenticated realm!\n\r");
	}
	else {
		printf("[DEBUG] Authenticated realm: %s\n\r", data ? data : "(NULL)");
	}

	result = sasl_getprop(conn, SASL_SSF, (const void **)&ssf);
	if (result != SASL_OK) {
		printf("[WARNING] Unable to determine SSF!\n\r");
	}
	else {
		printf("[DEBUG] Authenticated SSF: %d\n", *ssf);
	}

	// RAJA FIXME
	if (user_authorized == 1) {
		// Send list of available servers...
		write_data_to_client(netfd, "OK�", strlen("OK�"));
	}

	write_data_to_client(netfd, "TESTING", strlen("TESTING"));

	return 0;
}

/*
  The AuthServer class handles new connections to the server. For every
  client that connects, it creates a new AuthSocket -- that instance is now
  responsible for the communication with that client.
*/
AuthServer::AuthServer(TQObject* parent) :
	TQServerSocket( 4004, 1, parent ) {

	if ( !ok() ) {
		printf("[ERROR] Failed to bind to port 4004\n\r");
		exit(1);
	}
}

AuthServer::~AuthServer() {
	//
}

void AuthServer::newConnection(int socket) {
	AuthSocket *s = new AuthSocket(socket, this);
	s->m_remoteHost = s->peerAddress().toString();
	printf("[DEBUG] New connection from %s\n\r", s->m_remoteHost.ascii());
	if (s->initiateKerberosHandshake() != 0) {
		s->close();
	}
	else {
		emit newConnect(s);
	}
}