/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/*
 * Copyright (C) 2003-2006 Imendio AB
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <config.h>

#include <string.h>
#include <glib.h>

#include "lm-debug.h"
#include "lm-error.h"
#include "lm-ssl-base.h"
#include "lm-ssl-internals.h"

#ifdef HAVE_GNUTLS

#include <gnutls/x509.h>

#define CA_PEM_FILE "/etc/ssl/certs/ca-certificates.crt"

struct _LmSSL {
	LmSSLBase base;

	gnutls_session                 gnutls_session;
	gnutls_certificate_credentials gnutls_xcred;
	gboolean                       started;
};

static gboolean       ssl_verify_certificate    (LmSSL       *ssl,
						 const gchar *server);

static gboolean
ssl_verify_certificate (LmSSL *ssl, const gchar *server)
{
	LmSSLBase *base;
	unsigned int        status;
	int rc;

	base = LM_SSL_BASE (ssl);

	/* This verification function uses the trusted CAs in the credentials
	 * structure. So you must have installed one or more CA certificates.
	 */
	rc = gnutls_certificate_verify_peers2 (ssl->gnutls_session, &status);

	if (rc == GNUTLS_E_NO_CERTIFICATE_FOUND) {
		if (base->func (ssl,
			       LM_SSL_STATUS_NO_CERT_FOUND,
			       base->func_data) != LM_SSL_RESPONSE_CONTINUE) {
			return FALSE;
		}
	}

	if (rc != 0) {
		if (base->func (ssl,
			       LM_SSL_STATUS_GENERIC_ERROR,
			       base->func_data) != LM_SSL_RESPONSE_CONTINUE) {
			return FALSE;
		}
	}

	if (rc == GNUTLS_E_NO_CERTIFICATE_FOUND) {
		if (base->func (ssl,
			       LM_SSL_STATUS_NO_CERT_FOUND,
			       base->func_data) != LM_SSL_RESPONSE_CONTINUE) {
			return FALSE;
		}
	}
	
	if (status & GNUTLS_CERT_INVALID
	    || status & GNUTLS_CERT_REVOKED) {
		if (base->func (ssl, LM_SSL_STATUS_UNTRUSTED_CERT,
			       base->func_data) != LM_SSL_RESPONSE_CONTINUE) {
			return FALSE;
		}
	}
	
	if (gnutls_certificate_expiration_time_peers (ssl->gnutls_session) < time (0)) {
		if (base->func (ssl, LM_SSL_STATUS_CERT_EXPIRED,
			       base->func_data) != LM_SSL_RESPONSE_CONTINUE) {
			return FALSE;
		}
	}
	
	if (gnutls_certificate_activation_time_peers (ssl->gnutls_session) > time (0)) {
		if (base->func (ssl, LM_SSL_STATUS_CERT_NOT_ACTIVATED,
			       base->func_data) != LM_SSL_RESPONSE_CONTINUE) {
			return FALSE;
		}
	}
	
	if (gnutls_certificate_type_get (ssl->gnutls_session) == GNUTLS_CRT_X509) {
		const gnutls_datum* cert_list;
		guint cert_list_size;
		size_t digest_size;
		gnutls_x509_crt cert;
		
		cert_list = gnutls_certificate_get_peers (ssl->gnutls_session, &cert_list_size);
		if (cert_list == NULL) {
			if (base->func (ssl, LM_SSL_STATUS_NO_CERT_FOUND,
				       base->func_data) != LM_SSL_RESPONSE_CONTINUE) {
				return FALSE;
			}
		}

		gnutls_x509_crt_init (&cert);

		if (gnutls_x509_crt_import (cert, &cert_list[0],
					     GNUTLS_X509_FMT_DER) != 0) {
			if (base->func (ssl, LM_SSL_STATUS_NO_CERT_FOUND, 
					base->func_data) != LM_SSL_RESPONSE_CONTINUE) {
				return FALSE;
			}
		}

		if (!gnutls_x509_crt_check_hostname (cert, server)) {
			if (base->func (ssl, LM_SSL_STATUS_CERT_HOSTNAME_MISMATCH,
				       base->func_data) != LM_SSL_RESPONSE_CONTINUE) {
				return FALSE;
			}
		}

		gnutls_x509_crt_deinit (cert);

		digest_size = sizeof (base->fingerprint);

		if (gnutls_fingerprint (GNUTLS_DIG_MD5, &cert_list[0],
					base->fingerprint,
					&digest_size) >= 0) {
			if (base->expected_fingerprint &&
			    memcmp (base->expected_fingerprint, 
				    base->fingerprint,
				    digest_size) &&
			    base->func (ssl,
				       LM_SSL_STATUS_CERT_FINGERPRINT_MISMATCH,
				       base->func_data) != LM_SSL_RESPONSE_CONTINUE) {
				return FALSE;
			}
		} 
		else if (base->func (ssl, LM_SSL_STATUS_GENERIC_ERROR,
				     base->func_data) != LM_SSL_RESPONSE_CONTINUE) {
			return FALSE; 
		} 
	}

	return TRUE;
}

/* From lm-ssl-protected.h */

LmSSL *
_lm_ssl_new (const gchar    *expected_fingerprint,
	    LmSSLFunction   ssl_function,
	    gpointer        user_data,
	    GDestroyNotify  notify)
{
	LmSSL *ssl;

	ssl = g_new0 (LmSSL, 1);

	_lm_ssl_base_init ((LmSSLBase *) ssl,
			   expected_fingerprint,
			   ssl_function, user_data, notify);

	return ssl;
}

void
_lm_ssl_initialize (LmSSL *ssl) 
{
	gnutls_global_init ();
	gnutls_certificate_allocate_credentials (&ssl->gnutls_xcred);
	gnutls_certificate_set_x509_trust_file(ssl->gnutls_xcred,
					       CA_PEM_FILE,
					       GNUTLS_X509_FMT_PEM);
}

gboolean
_lm_ssl_begin (LmSSL *ssl, gint fd, const gchar *server, GError **error)
{
	int ret;
	gboolean auth_ok = TRUE;
	const int cert_type_priority[] =
		{ GNUTLS_CRT_X509, GNUTLS_CRT_OPENPGP, 0 };
	const int compression_priority[] =
		{ GNUTLS_COMP_DEFLATE, GNUTLS_COMP_NULL, 0 };

	gnutls_init (&ssl->gnutls_session, GNUTLS_CLIENT);
	gnutls_set_default_priority (ssl->gnutls_session);
	gnutls_certificate_type_set_priority (ssl->gnutls_session,
					      cert_type_priority);
	gnutls_compression_set_priority (ssl->gnutls_session,
					 compression_priority);
	gnutls_credentials_set (ssl->gnutls_session,
				GNUTLS_CRD_CERTIFICATE,
				ssl->gnutls_xcred);

	gnutls_transport_set_ptr (ssl->gnutls_session,
				  (gnutls_transport_ptr_t) fd);

	ret = gnutls_handshake (ssl->gnutls_session);

	if (ret >= 0) {
		auth_ok = ssl_verify_certificate (ssl, server);
	}

	if (ret < 0 || !auth_ok) {
		char *errmsg;

		gnutls_perror (ret);
	
		if (!auth_ok) {
			errmsg = "*** GNUTLS authentication error";
		} else {
			errmsg = "*** GNUTLS handshake failed";
		}

		g_set_error (error, 
			     LM_ERROR, LM_ERROR_CONNECTION_OPEN,
			     errmsg);			

		return FALSE;
	}
	lm_verbose ("GNUTLS negotiated compression: %s",
		    gnutls_compression_get_name (gnutls_compression_get
			(ssl->gnutls_session)));

	ssl->started = TRUE;

	return TRUE;
}

GIOStatus
_lm_ssl_read (LmSSL *ssl, gchar *buf, gint len, gsize *bytes_read)
{
	GIOStatus status;
	gint      b_read;

	*bytes_read = 0;
	b_read = gnutls_record_recv (ssl->gnutls_session, buf, len);

	if (b_read == GNUTLS_E_AGAIN) {
		status = G_IO_STATUS_AGAIN;
	}
	else if (b_read == 0) {
		status = G_IO_STATUS_EOF;
	}
	else if (b_read < 0) {
		status = G_IO_STATUS_ERROR;
	} else {
		*bytes_read = (guint) b_read;
		status = G_IO_STATUS_NORMAL;
	}

	return status;
}

gint
_lm_ssl_send (LmSSL *ssl, const gchar *str, gint len)
{
	gint bytes_written;

	bytes_written = gnutls_record_send (ssl->gnutls_session, str, len);

	while (bytes_written < 0) {
		if (bytes_written != GNUTLS_E_INTERRUPTED &&
		    bytes_written != GNUTLS_E_AGAIN) {
			return -1;
		}
	
		bytes_written = gnutls_record_send (ssl->gnutls_session, 
						    str, len);
	}

	return bytes_written;
}

void 
_lm_ssl_close (LmSSL *ssl)
{
	if (!ssl->started)
		return;

	gnutls_deinit (ssl->gnutls_session);
	gnutls_certificate_free_credentials (ssl->gnutls_xcred);
	gnutls_global_deinit ();
}

void
_lm_ssl_free (LmSSL *ssl)
{
	_lm_ssl_base_free_fields (LM_SSL_BASE (ssl));
	g_free (ssl);
}

#endif /* HAVE_GNUTLS */