/*
 *  csync2 - cluster synchronization tool, 2nd generation
 *  Copyright (C) 2004 - 2015 LINBIT Information Technologies GmbH
 *  http://www.linbit.com; see also AUTHORS
 *
 *  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 2 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
 */

#include "csync2.h"
#include <stdarg.h>
#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <unistd.h>
#include <netdb.h>
#include <errno.h>

#ifdef HAVE_LIBGNUTLS
#  include <gnutls/gnutls.h>
#  include <gnutls/x509.h>
#endif

int conn_fd_in  = -1;
int conn_fd_out = -1;
int conn_clisok = 0;

#ifdef HAVE_LIBGNUTLS
int csync_conn_usessl = 0;

static gnutls_session_t conn_tls_session;
static gnutls_certificate_credentials_t conn_x509_cred;
#endif

static const char *__response[] = {
	[CR_OK_CMD_FINISHED] = "OK (cmd_finished).",
	[CR_OK_DATA_FOLLOWS] = "OK (data_follows).",
	[CR_OK_SEND_DATA] = "OK (send_data).",
	[CR_OK_NOT_FOUND] = "OK (not_found).",
	[CR_OK_PATH_NOT_FOUND] = "OK (path_not_found).",
	[CR_OK_CU_LATER] = "OK (cu_later).",
	[CR_OK_ACTIVATING_SSL] = "OK (activating_ssl).",

	/* CR_ERROR: all sorts of strings; often strerror(errno) */

	/* more specific errors: */
	[CR_ERR_CONN_CLOSED] = "Connection closed.",
	[CR_ERR_ALSO_DIRTY_HERE] = "File is also marked dirty here!",
	[CR_ERR_PARENT_DIR_MISSING] = "Parent dir missing.",

	[CR_ERR_GROUP_LIST_ALREADY_SET] = "Group list already set!",
	[CR_ERR_IDENTIFICATION_FAILED] = "Identification failed!",
	[CR_ERR_PERM_DENIED_FOR_SLAVE] = "Permission denied for slave!",
	[CR_ERR_PERM_DENIED] = "Permission denied!",
	[CR_ERR_SSL_EXPECTED] = "SSL encrypted connection expected!",
	[CR_ERR_UNKNOWN_COMMAND] = "Unkown command!",
	[CR_ERR_WIN32_EIO_CREATE_DIR] = "Win32 I/O Error on CreateDirectory()",
};

static const int __response_size = sizeof(__response)/sizeof(__response[0]);

const char *conn_response(unsigned i)
{
	if (i < __response_size
	&& __response[i]
	&& __response[i][0])
		return __response[i];

	csync_fatal("BUG! No such response: %u\n", i);
	return NULL;
}

static const unsigned int response_len(unsigned i)
{
	static unsigned int __response_len[sizeof(__response)/sizeof(__response[0])];
	static int initialized;
	if (!initialized) {
		unsigned int j;
		for (j = 0; j < __response_size; j++)
			__response_len[j] = strlen(__response[j] ?: "");
		initialized = 1;
	}
	return (i < __response_size) ? __response_len[i] : 0;
}

enum connection_response conn_response_to_enum(const char *response)
{
	unsigned int i, len;
	for (i = 0; i < __response_size; i++) {
		len = response_len(i);
		if (len && !strncmp(__response[i], response, len))
			return i;
	}
	/* may be a new OK code? */
	if (!strncmp(response, "OK (", 4))
		return CR_OK;
	else
		return CR_ERROR;
}

static void csync_client_bind(int sfd, struct addrinfo *peer_ai)
{
	struct addrinfo hints;
	struct addrinfo *result, *rp;
	int s;

	if (!bind_to_myhostname)
		return;

	memset(&hints, 0, sizeof(struct addrinfo));
	hints.ai_family = peer_ai->ai_family;
	hints.ai_socktype = SOCK_STREAM;

	s = getaddrinfo(bind_to_myhostname ? myhostname : NULL, 0, &hints, &result);
	if (s != 0) {
		csync_debug(1, "Cannot prepare local socket for bind, getaddrinfo: %s\n", gai_strerror(s));
		return;
	}

	for (rp = result; rp != NULL; rp = rp->ai_next) {
		if (bind(sfd, rp->ai_addr, rp->ai_addrlen) == 0)
			break;	/* Success */
	}

	if (rp != NULL) {
		char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
		if (getnameinfo(rp->ai_addr, rp->ai_addrlen,
				hbuf, sizeof(hbuf), sbuf, sizeof(sbuf),
				NI_NUMERICHOST | NI_NUMERICSERV) == 0)
			csync_debug(1, "Bound to %s:%s as %s.\n",
				hbuf, sbuf, myhostname);
		else
			/* WTF, is failure even possible here?
			 * Anyways, bind() did not report an error. */
			csync_debug(1, "Bound local socket as %s.\n", myhostname);
	} else
		/* So bind() failed. Ignore, and try to connect anyways.
		 * Maybe it still works, maybe identification paranoia of the
		 * peer will kick us out. */
		csync_debug(1, "Local socket bind() to %s failed; ignored.\n", myhostname);

	freeaddrinfo(result);	/* No longer needed */
}

/* getaddrinfo stuff mostly copied from its manpage */
int conn_connect(const char *peername)
{
	struct addrinfo hints;
	struct addrinfo *result, *rp;
	int save_errno = 0;
	int sfd = -1, s;

	/* Obtain address(es) matching host/port */
	memset(&hints, 0, sizeof(struct addrinfo));
	hints.ai_family = AF_UNSPEC;	/* Allow IPv4 or IPv6 */
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_flags = 0;
	hints.ai_protocol = 0;	/* Any protocol */

	s = getaddrinfo(peername, csync_port, &hints, &result);
	if (s != 0) {
		csync_debug(1, "Cannot resolve peername, getaddrinfo: %s\n", gai_strerror(s));
		return -1;
	}

	/* getaddrinfo() returns a list of address structures.
	   Try each address until we successfully connect(2).
	   If socket(2) (or connect(2)) fails, we (close the socket
	   and) try the next address. */

	for (rp = result; rp != NULL; rp = rp->ai_next) {
		sfd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
		if (sfd == -1)
			continue;

		/* If called with -N somehostname, try to bind to that name.
		 * If that fails, ignore, and try the connect anyways. */
		csync_client_bind(sfd, rp);

		if (connect(sfd, rp->ai_addr, rp->ai_addrlen) != -1)
			break;	/* Success */
		save_errno = errno;

		close(sfd);
		sfd = -1;
	}

	if (sfd != -1) {
		char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
		if (getnameinfo(rp->ai_addr, rp->ai_addrlen,
				hbuf, sizeof(hbuf), sbuf, sizeof(sbuf),
				NI_NUMERICHOST | NI_NUMERICSERV) == 0)
			csync_debug(1, "Connect to %s:%s (%s).\n",
				hbuf, sbuf, peername);
		else
			/* WTF, is failure even possible here? */
			csync_debug(1, "Connect to <?>:%s (%s).\n",
				csync_port, peername);
	}

	freeaddrinfo(result);	/* No longer needed */

	if (sfd == -1 && save_errno)
		errno = save_errno;

	return sfd;
}

int conn_open(const char *peername)
{
	int on = 1;

        conn_fd_in = conn_connect(peername);
        if (conn_fd_in < 0) {
                csync_debug(1, "Can't create socket: %s\n", strerror(errno));
                return -1;
        }

	if (setsockopt(conn_fd_in, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on) ) < 0) {
                csync_debug(2, "Can't set TCP_NODELAY option on TCP socket.\n");
		close(conn_fd_in); conn_fd_in = -1;
                return -1;
	}

	conn_fd_out = conn_fd_in;
	conn_clisok = 1;
#ifdef HAVE_LIBGNUTLS
	csync_conn_usessl = 0;
#endif
	return 0;
}

int conn_set(int infd, int outfd)
{
	int on = 1;

	conn_fd_in  = infd;
	conn_fd_out = outfd;
	conn_clisok = 1;
#ifdef HAVE_LIBGNUTLS
	csync_conn_usessl = 0;
#endif

	// when running in server mode, this has been done already
	// in csync2.c with more restrictive error handling..
	// FIXME don't even try in "ssh" mode
	if ( setsockopt(conn_fd_out, IPPROTO_TCP, TCP_NODELAY, &on, (socklen_t) sizeof(on)) < 0 )
                csync_debug(2, "Can't set TCP_NODELAY option on TCP socket.\n");

	return 0;
}


#ifdef HAVE_LIBGNUTLS

static void ssl_log(int level, const char* msg)
{ csync_debug(level, "%s", msg); }

int conn_activate_ssl(int server_role)
{
	gnutls_alert_description_t alrt;
	char *ssl_keyfile;
	char *ssl_certfile;
	int err;
	int handshake_repeat = 0;

	if (csync_conn_usessl)
		return 0;

	ASPRINTF(&ssl_keyfile, "%s/csync2_ssl_key.pem", systemdir);
	ASPRINTF(&ssl_certfile, "%s/csync2_ssl_cert.pem", systemdir);

	gnutls_global_init();
	gnutls_global_set_log_function(ssl_log);
	gnutls_global_set_log_level(10);

	gnutls_certificate_allocate_credentials(&conn_x509_cred);

	err = gnutls_certificate_set_x509_key_file(conn_x509_cred, ssl_certfile, ssl_keyfile, GNUTLS_X509_FMT_PEM);
	if(err != GNUTLS_E_SUCCESS) {
		gnutls_certificate_free_credentials(conn_x509_cred);
		gnutls_global_deinit();

		csync_fatal(
			"SSL: failed to use key file %s and/or certificate file %s: %s (%s)\n",
			ssl_keyfile,
			ssl_certfile,
			gnutls_strerror(err),
			gnutls_strerror_name(err)
		);
	}

	if(server_role) {
		gnutls_certificate_free_cas(conn_x509_cred);

		if(gnutls_certificate_set_x509_trust_file(conn_x509_cred, ssl_certfile, GNUTLS_X509_FMT_PEM) < 1) {
			gnutls_certificate_free_credentials(conn_x509_cred);
			gnutls_global_deinit();

			csync_fatal(
				"SSL: failed to use certificate file %s as CA.\n",
				ssl_certfile
			);
		}
	} else
		gnutls_certificate_free_ca_names(conn_x509_cred);

	gnutls_init(&conn_tls_session, (server_role ? GNUTLS_SERVER : GNUTLS_CLIENT));
	gnutls_priority_set_direct(conn_tls_session, "PERFORMANCE", NULL);
	gnutls_credentials_set(conn_tls_session, GNUTLS_CRD_CERTIFICATE, conn_x509_cred);

	if(server_role) {
		gnutls_certificate_send_x509_rdn_sequence(conn_tls_session, 0);
		gnutls_certificate_server_set_request(conn_tls_session, GNUTLS_CERT_REQUIRE);
	}

	gnutls_transport_set_ptr2(
		conn_tls_session,
		(gnutls_transport_ptr_t)(long)conn_fd_in,
		(gnutls_transport_ptr_t)(long)conn_fd_out
	);


	do {
		handshake_repeat = 0;
		err = gnutls_handshake(conn_tls_session);
		switch(err) {
		case GNUTLS_E_SUCCESS:
			break;

		case GNUTLS_E_WARNING_ALERT_RECEIVED:
			alrt = gnutls_alert_get(conn_tls_session);
			fprintf(
				csync_debug_out,
				"SSL: warning alert received from peer: %d (%s).\n",
				alrt, gnutls_alert_get_name(alrt)
			);
			handshake_repeat = 1;
			break;

		case GNUTLS_E_FATAL_ALERT_RECEIVED:
			alrt = gnutls_alert_get(conn_tls_session);
			fprintf(
				csync_debug_out,
				"SSL: fatal alert received from peer: %d (%s).\n",
				alrt, gnutls_alert_get_name(alrt)
			);
			// fall-through!

		default:
			gnutls_bye(conn_tls_session, GNUTLS_SHUT_RDWR);
			gnutls_deinit(conn_tls_session);
			gnutls_certificate_free_credentials(conn_x509_cred);
			gnutls_global_deinit();

			csync_fatal(
				"SSL: handshake failed: %s (%s)\n",
				gnutls_strerror(err),
				gnutls_strerror_name(err)
			);
		}
	} while (handshake_repeat);

	csync_conn_usessl = 1;

	return 0;
}

int conn_check_peer_cert(const char *peername, int callfatal)
{
	const gnutls_datum_t *peercerts;
	unsigned npeercerts;
	int i, cert_is_ok = -1;

	if (!csync_conn_usessl)
		return 1;

	peercerts = gnutls_certificate_get_peers(conn_tls_session, &npeercerts);
	if(peercerts == NULL || npeercerts == 0) {
		if (callfatal)
			csync_fatal("Peer did not provide an SSL X509 cetrificate.\n");
		csync_debug(1, "Peer did not provide an SSL X509 cetrificate.\n");
		return 0;
	}

	{
		char certdata[2*peercerts[0].size + 1];

		for (i=0; i<peercerts[0].size; i++)
			sprintf(&certdata[2*i], "%02X", peercerts[0].data[i]);
		certdata[2*i] = 0;

		SQL_BEGIN("Checking peer x509 certificate.",
			"SELECT certdata FROM x509_cert WHERE peername = '%s'",
			url_encode(peername))
		{
			if (!strcmp(SQL_V(0), certdata))
				cert_is_ok = 1;
			else
				cert_is_ok = 0;
		} SQL_END;

		if (cert_is_ok < 0) {
			csync_debug(1, "Adding peer x509 certificate to db: %s\n", certdata);
			SQL("Adding peer x509 sha1 hash to database.",
				"INSERT INTO x509_cert (peername, certdata) VALUES ('%s', '%s')",
				url_encode(peername), url_encode(certdata));
			return 1;
		}

		csync_debug(2, "Peer x509 certificate is: %s\n", certdata);

		if (!cert_is_ok) {
			if (callfatal)
				csync_fatal("Peer did provide a wrong SSL X509 cetrificate.\n");
			csync_debug(1, "Peer did provide a wrong SSL X509 cetrificate.\n");
			return 0;
		}
	}

	return 1;
}

#else

int conn_check_peer_cert(const char *peername, int callfatal)
{
	return 1;
}

#endif /* HAVE_LIBGNUTLS */

int conn_close()
{
	if ( !conn_clisok ) return -1;

#ifdef HAVE_LIBGNUTLS
	if ( csync_conn_usessl ) {
		gnutls_bye(conn_tls_session, GNUTLS_SHUT_RDWR);
		gnutls_deinit(conn_tls_session);
		gnutls_certificate_free_credentials(conn_x509_cred);
		gnutls_global_deinit();
	}
#endif

	if ( conn_fd_in != conn_fd_out) close(conn_fd_in);
	close(conn_fd_out);

	conn_fd_in  = -1;
	conn_fd_out = -1;
	conn_clisok =  0;

	return 0;
}

static inline int READ(void *buf, size_t count)
{
#ifdef HAVE_LIBGNUTLS
	if (csync_conn_usessl)
		return gnutls_record_recv(conn_tls_session, buf, count);
	else
#endif
		return read(conn_fd_in, buf, count);
}

static inline int WRITE(const void *buf, size_t count)
{
	static int n, total;

#ifdef HAVE_LIBGNUTLS
	if (csync_conn_usessl)
		return gnutls_record_send(conn_tls_session, buf, count);
	else
#endif
	{
		total = 0;

		while (count > total) {
			n = write(conn_fd_out, ((char *) buf) + total, count - total);

			if (n >= 0)
				total += n;
			else {
				if (errno == EINTR)
					continue;
				else
					return -1;
			}
		}

		return total;
	}
}

int conn_raw_read(void *buf, size_t count)
{
	static char buffer[512];
	static int buf_start=0, buf_end=0;

	if ( buf_start == buf_end ) {
		if (count > 128)
			return READ(buf, count);
		else {
			buf_start = 0;
			buf_end = READ(buffer, 512);
			if (buf_end < 0) { buf_end=0; return -1; }
		}
	}

	if ( buf_start < buf_end ) {
		size_t real_count = buf_end - buf_start;
		if ( real_count > count ) real_count = count;

		memcpy(buf, buffer+buf_start, real_count);
		buf_start += real_count;

		return real_count;
	}

	return 0;
}

struct conn_debug_buf {
	char *pos;
	size_t rlen;
};

static void buf_printf(struct conn_debug_buf *b, const char *fmt, ...)
{
	va_list ap;
	int c;

	if (b->rlen <= 0)
		return;

	va_start(ap, fmt);
	c = vsnprintf(b->pos, b->rlen, fmt, ap);
	va_end(ap);

	if (c >= b->rlen) {
		b->pos[b->rlen - 1] = '\0';
		c = b->rlen;
	}
	if (c >= 0) {
		b->rlen -= c;
		b->pos += c;
	}
}

void conn_debug(const char *name, const char*buf, size_t count)
{
	char buffer[1024];
	struct conn_debug_buf b = {
		.pos = buffer,
		.rlen = sizeof(buffer)
	};
	int i;

	if ( csync_debug_level < 3 ) return;

	if (csync_server_child_pid)
		buf_printf(&b, "<%d> ", csync_server_child_pid);
	buf_printf(&b, "%s> ", name);
	for (i=0; i<count; i++) {
		switch (buf[i]) {
			case '\n':
				buf_printf(&b, "\\n");
				break;
			case '\r':
				buf_printf(&b, "\\r");
				break;
			default:
				if (buf[i] < 32 || buf[i] >= 127)
					buf_printf(&b, "\\%03o", buf[i]);
				else
					buf_printf(&b, "%c", buf[i]);
				break;
		}
	}
	fprintf(csync_debug_out, "%s\n", buffer);
}

int conn_read(void *buf, size_t count)
{
	int pos, rc;

	for (pos=0; pos < count; pos+=rc) {
		rc = conn_raw_read(buf+pos, count-pos);
		if (rc <= 0) return pos;
	}

	conn_debug("Peer", buf, pos);
	return pos;
}

int conn_write(const void *buf, size_t count)
{
	conn_debug("Local", buf, count);
	return WRITE(buf, count);
}

void conn_printf(const char *fmt, ...)
{
	char dummy, *buffer;
	va_list ap;
	int size;

	va_start(ap, fmt);
	size = vsnprintf(&dummy, 1, fmt, ap);
	buffer = alloca(size+1);
	va_end(ap);

	va_start(ap, fmt);
	vsnprintf(buffer, size+1, fmt, ap);
	va_end(ap);

	conn_write(buffer, size);
}

size_t conn_gets(char *s, size_t size)
{
	size_t i=0;

	while (i<size-1) {
		int rc = conn_raw_read(s+i, 1);
		if (rc != 1) break;
		if (s[i++] == '\n') break;
	}
	s[i] = 0;

	conn_debug("Peer", s, i);
	if (i > 1 && s[i-1] != '\n')
		csync_fatal("Received line too long for buffer size (%u), giving up.\n", size);
	return i;
}