/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */

/*

 * Copyright (C) 2007 Collabora Ltd.

 *

 * 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 <stdio.h>

#include <string.h>

#include <glib.h>

#include "lm-sock.h"

#include "lm-debug.h"

#include "lm-error.h"

#include "lm-internals.h"

#include "lm-message-queue.h"

#include "lm-misc.h"

#include "lm-ssl-internals.h"

#include "lm-parser.h"

#include "lm-sha.h"

#include "lm-connection.h"

#include "lm-utils.h"

#include "lm-socket.h"

#include "lm-sasl.h"

#include "md5.h"

#include "base64.h"

typedef enum {

	AUTH_TYPE_PLAIN  = 1,

	AUTH_TYPE_DIGEST = 2

} AuthType;

typedef enum {

	SASL_AUTH_STATE_NO_MECH,

	SASL_AUTH_STATE_PLAIN_STARTED,

	SASL_AUTH_STATE_DIGEST_MD5_STARTED,

	SASL_AUTH_STATE_DIGEST_MD5_SENT_AUTH_RESPONSE,

	SASL_AUTH_STATE_DIGEST_MD5_SENT_FINAL_RESPONSE,

} SaslAuthState;

struct _LmSASL {

	LmConnection        *connection;

	AuthType             auth_type;

	SaslAuthState        state;

	gchar               *username;

	gchar               *password;

	gchar               *server;

	gchar               *digest_md5_rspauth;

	LmMessageHandler    *features_cb;

	LmMessageHandler    *challenge_cb;

	LmMessageHandler    *success_cb;

	LmMessageHandler    *failure_cb;

	gboolean             features_received;

	gboolean             start_auth;

	LmSASLResultHandler  handler;

};

#define XMPP_NS_SASL_AUTH "urn:ietf:params:xml:ns:xmpp-sasl"

static LmHandlerResult     sasl_features_cb  (LmMessageHandler *handler,

					      LmConnection     *connection,

					      LmMessage        *message,

					      gpointer          user_data);

static LmHandlerResult     sasl_challenge_cb (LmMessageHandler *handler,

					      LmConnection     *connection,

					      LmMessage        *message,

					      gpointer          user_data);

static LmHandlerResult     sasl_success_cb   (LmMessageHandler *handler,

					      LmConnection     *connection,

					      LmMessage        *message,

					      gpointer          user_data);

static LmHandlerResult     sasl_failure_cb   (LmMessageHandler *handler,

					      LmConnection     *connection,

					      LmMessage        *message,

					      gpointer          user_data);

/* DIGEST-MD5 mechanism code from libgibber */

static gchar *

sasl_strndup_unescaped (const gchar *str, gsize len) 

{

	const gchar *s;

	gchar       *d;

	gchar       *ret;

	ret = g_malloc0 (len + 1);

	for (s = str, d = ret ; s < (str + len) ; s++, d++) {

		if (*s == '\\') s++;

		*d = *s;

	}

	return ret;

}

static GHashTable *

sasl_digest_md5_challenge_to_hash (const gchar * challenge)

{

	const gchar *keystart, *keyend, *valstart;

	const gchar *c = challenge;

	gchar       *key, *val;

	GHashTable  *result;

	result = g_hash_table_new_full (g_str_hash, g_str_equal, 

					g_free, g_free);

	do { 

		while (g_ascii_isspace(*c)) c++;

		keystart = c;

		for (; *c != '\0' && *c != '='; c++);

		if (*c == '\0' || c == keystart) goto error;

		keyend = c; 

		c++;

		if (*c == '"') {

			c++;

			valstart = c;

			for (; *c != '\0' && *c != '"'; c++);

			if (*c == '\0' || c == valstart) goto error;

			val = sasl_strndup_unescaped (valstart, c - valstart);

			c++;

		} else {

			valstart = c;

			for (; *c !=  '\0' && *c != ','; c++);

			if (c == valstart) goto error;

			val = g_strndup (valstart, c - valstart);

		}

		key = g_strndup (keystart, keyend - keystart);

		g_hash_table_insert (result, key, val);

		if (*c == ',') c++;

	} while (*c != '\0');

	return result;

error:

	g_log (LM_LOG_DOMAIN, LM_LOG_LEVEL_SASL, 

	       "Failed to parse challenge: %s", challenge);

	g_hash_table_destroy (result);

	return NULL;

}

static gchar *

sasl_md5_hex_hash (gchar *value, gsize len) 

{

	md5_byte_t   digest_md5[16];

	md5_state_t  md5_calc;

	GString     *str;

	int          i;

	str = g_string_sized_new (32);

	md5_init (&md5_calc);

	md5_append (&md5_calc, (const md5_byte_t *)value, len);

	md5_finish (&md5_calc, digest_md5);

	for (i = 0 ; i < 16 ; i++) {

		g_string_append_printf (str, "%02x", digest_md5[i]);

	}

	return g_string_free (str, FALSE);

}

static gchar *

sasl_digest_md5_generate_cnonce(void)

{

	/* RFC 2831 recommends the the nonce to be either hexadecimal or base64 with

	 * at least 64 bits of entropy */

#define NR 8

	guint32 n[NR]; 

	int i;

	for (i = 0; i < NR; i++) {

		n[i] = g_random_int();

	}

	return base64_encode ((gchar *)n, sizeof(n));

}

static gchar *

sasl_md5_prepare_response (LmSASL *sasl, GHashTable *challenge)

{

	GString     *response;

	const gchar *realm, *nonce;

	gchar       *a1, *a1h, *a2, *a2h, *kd, *kdh;

	gchar       *cnonce = NULL;

	gchar       *tmp;

	md5_byte_t   digest_md5[16];

	md5_state_t  md5_calc;

	gsize        len;

	response = g_string_new ("");

	if (sasl->username == NULL || sasl->password == NULL) {

		g_log (LM_LOG_DOMAIN, LM_LOG_LEVEL_SASL,

		       "%s: no username or password provided", G_STRFUNC);

		if (sasl->handler) {

			sasl->handler (sasl, sasl->connection, 

				       FALSE, "no username/password provided");

		}

		goto error;

	}

	nonce = g_hash_table_lookup (challenge, "nonce");

	if (nonce == NULL || nonce == '\0') {

		g_log (LM_LOG_DOMAIN, LM_LOG_LEVEL_SASL,

		       "%s: server didn't provide a nonce in the challenge", 

		       G_STRFUNC);

		if (sasl->handler) {

			sasl->handler (sasl, sasl->connection,

				       FALSE, "server error");

		}

		goto error;

	}

	cnonce = sasl_digest_md5_generate_cnonce ();

	/* FIXME challenge can contain multiple realms */

	realm = g_hash_table_lookup (challenge, "realm");

	if (realm == NULL) {

		realm = sasl->server;

	}

	/* FIXME properly escape values */

	g_string_append_printf (response, "username=\"%s\"", sasl->username);

	g_string_append_printf (response, ",realm=\"%s\"", realm);

	g_string_append_printf (response, ",digest-uri=\"xmpp/%s\"", realm);

	g_string_append_printf (response, ",nonce=\"%s\",nc=00000001", nonce);

	g_string_append_printf (response, ",cnonce=\"%s\"", cnonce);

	/* FIXME should check if auth is in the cop challenge val */

	g_string_append_printf (response, ",qop=auth,charset=utf-8");

	tmp = g_strdup_printf ("%s:%s:%s", 

			       sasl->username, realm, sasl->password);

	md5_init (&md5_calc);

	md5_append (&md5_calc, (const md5_byte_t *)tmp, strlen(tmp));

	md5_finish (&md5_calc, digest_md5);

	g_free (tmp);

	a1 = g_strdup_printf ("0123456789012345:%s:%s", nonce, cnonce);

	len = strlen (a1);

	memcpy (a1, digest_md5, 16);

	a1h = sasl_md5_hex_hash (a1, len);

	a2 = g_strdup_printf ("AUTHENTICATE:xmpp/%s", realm);

	a2h = sasl_md5_hex_hash (a2, strlen(a2));

	kd = g_strdup_printf ("%s:%s:00000001:%s:auth:%s",

			      a1h, nonce, cnonce, a2h);

	kdh = sasl_md5_hex_hash (kd, strlen(kd));

	g_string_append_printf (response, ",response=%s", kdh);

	g_free (kd);

	g_free (kdh);

	g_free (a2);

	g_free (a2h);

	/* Calculate the response we expect from the server */

	a2 = g_strdup_printf (":xmpp/%s", realm);

	a2h = sasl_md5_hex_hash (a2, strlen(a2));

	kd = g_strdup_printf ("%s:%s:00000001:%s:auth:%s", a1h, nonce, cnonce, a2h);

	g_free (sasl->digest_md5_rspauth);

	sasl->digest_md5_rspauth = sasl_md5_hex_hash (kd, strlen(kd));

	g_free (a1);

	g_free (a1h);

	g_free (a2);

	g_free (a2h);

	g_free (kd);

out:

	g_free (cnonce);

	if (response) {

		return g_string_free (response, FALSE);

	} else {

		return NULL;

	}

error:

	g_string_free (response, TRUE);

	response = NULL;

	goto out;

}

static gboolean

sasl_digest_md5_send_initial_response (LmSASL *sasl, GHashTable *challenge)

{

	LmMessage *msg;

	gchar     *response;

	gchar     *response64;

	int        result;

	response = sasl_md5_prepare_response(sasl, challenge);

	if (response == NULL) {

		return FALSE;

	}

	response64 = base64_encode ((gchar *)response, strlen(response));

	msg = lm_message_new (NULL, LM_MESSAGE_TYPE_RESPONSE);

	lm_message_node_set_attributes (msg->node,

					"xmlns", XMPP_NS_SASL_AUTH,

					NULL);

	lm_message_node_set_value (msg->node, response64);

	result = lm_connection_send (sasl->connection, msg, NULL);

	g_free (response);

	g_free (response64);

	lm_message_unref (msg);

	if (!result) {

		return FALSE;

	}

	sasl->state = SASL_AUTH_STATE_DIGEST_MD5_SENT_AUTH_RESPONSE;

	return TRUE;

}

static gboolean

sasl_digest_md5_check_server_response(LmSASL *sasl, GHashTable *challenge)

{

	LmMessage   *msg;

	const gchar *rspauth;

	int          result;

	rspauth = g_hash_table_lookup (challenge, "rspauth");

	if (rspauth == NULL) {

		g_log (LM_LOG_DOMAIN, LM_LOG_LEVEL_SSL,

		       "%s: server sent an invalid reply (no rspauth)\n",

		       G_STRFUNC);

		if (sasl->handler) {

			sasl->handler (sasl, sasl->connection, 

				       TRUE, "server error");

		}

		return FALSE;

	}

	if (strcmp (sasl->digest_md5_rspauth, rspauth) != 0) {

		g_log (LM_LOG_DOMAIN, LM_LOG_LEVEL_SSL,

		       "%s: server sent an invalid reply (rspauth not matching)\n", 

		       G_STRFUNC);

		if (sasl->handler) {

			sasl->handler (sasl, sasl->connection,

				       TRUE, "server error");

		}

		return FALSE;

	}

	msg = lm_message_new (NULL, LM_MESSAGE_TYPE_RESPONSE);

	lm_message_node_set_attributes (msg->node,

					"xmlns", XMPP_NS_SASL_AUTH,

					NULL);

	result = lm_connection_send (sasl->connection, msg, NULL);

	lm_message_unref (msg);

	if (!result) {

		g_warning ("Failed to send SASL response\n");

		return FALSE;

	}

	sasl->state = SASL_AUTH_STATE_DIGEST_MD5_SENT_FINAL_RESPONSE;

	return TRUE;

}

static gboolean

sasl_digest_md5_handle_challenge (LmSASL *sasl, LmMessageNode *node)

{

	const gchar *encoded;

	gchar       *challenge;

	gsize        len;