/*
 * Copyright (c) 2009-2012, Vsevolod Stakhov
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY AUTHOR ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL AUTHOR BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/***MODULE:spf
 * rspamd module that checks spf records of incoming email
 *
 * Allowed options:
 * - symbol_allow (string): symbol to insert (default: 'R_SPF_ALLOW')
 * - symbol_fail (string): symbol to insert (default: 'R_SPF_FAIL')
 * - symbol_softfail (string): symbol to insert (default: 'R_SPF_SOFTFAIL')
 * - whitelist (map): map of whitelisted networks
 */

#include "config.h"
#include "libmime/message.h"
#include "libmime/expressions.h"
#include "libserver/spf.h"
#include "libutil/hash.h"
#include "libutil/map.h"
#include "main.h"

#define DEFAULT_SYMBOL_FAIL "R_SPF_FAIL"
#define DEFAULT_SYMBOL_SOFTFAIL "R_SPF_SOFTFAIL"
#define DEFAULT_SYMBOL_NEUTRAL "R_SPF_NEUTRAL"
#define DEFAULT_SYMBOL_ALLOW "R_SPF_ALLOW"
#define DEFAULT_CACHE_SIZE 2048
#define DEFAULT_CACHE_MAXAGE 86400

struct spf_ctx {
	gint (*filter) (struct rspamd_task * task);
	const gchar *symbol_fail;
	const gchar *symbol_softfail;
	const gchar *symbol_neutral;
	const gchar *symbol_allow;

	rspamd_mempool_t *spf_pool;
	radix_compressed_t *whitelist_ip;
	rspamd_lru_hash_t *spf_hash;
};

static struct spf_ctx *spf_module_ctx = NULL;

static void spf_symbol_callback (struct rspamd_task *task, void *unused);
static GList * spf_record_copy (GList *addrs);
static void spf_record_destroy (gpointer list);

/* Initialization */
gint spf_module_init (struct rspamd_config *cfg, struct module_ctx **ctx);
gint spf_module_config (struct rspamd_config *cfg);
gint spf_module_reconfig (struct rspamd_config *cfg);

module_t spf_module = {
	"spf",
	spf_module_init,
	spf_module_config,
	spf_module_reconfig,
	NULL
};

gint
spf_module_init (struct rspamd_config *cfg, struct module_ctx **ctx)
{
	spf_module_ctx = g_malloc (sizeof (struct spf_ctx));

	spf_module_ctx->spf_pool = rspamd_mempool_new (
		rspamd_mempool_suggest_size ());

	*ctx = (struct module_ctx *)spf_module_ctx;

	return 0;
}


gint
spf_module_config (struct rspamd_config *cfg)
{
	const ucl_object_t *value;
	gint res = TRUE;
	guint cache_size, cache_expire;

	spf_module_ctx->whitelist_ip = radix_create_compressed ();

	if ((value =
		rspamd_config_get_module_opt (cfg, "spf", "symbol_fail")) != NULL) {
		spf_module_ctx->symbol_fail = ucl_obj_tostring (value);
	}
	else {
		spf_module_ctx->symbol_fail = DEFAULT_SYMBOL_FAIL;
	}
	if ((value =
		rspamd_config_get_module_opt (cfg, "spf", "symbol_softfail")) != NULL) {
		spf_module_ctx->symbol_softfail = ucl_obj_tostring (value);
	}
	else {
		spf_module_ctx->symbol_softfail = DEFAULT_SYMBOL_SOFTFAIL;
	}
	if ((value =
			rspamd_config_get_module_opt (cfg, "spf", "symbol_neutral")) != NULL) {
		spf_module_ctx->symbol_neutral = ucl_obj_tostring (value);
	}
	else {
		spf_module_ctx->symbol_neutral = DEFAULT_SYMBOL_NEUTRAL;
	}
	if ((value =
		rspamd_config_get_module_opt (cfg, "spf", "symbol_allow")) != NULL) {
		spf_module_ctx->symbol_allow = ucl_obj_tostring (value);
	}
	else {
		spf_module_ctx->symbol_allow = DEFAULT_SYMBOL_ALLOW;
	}
	if ((value =
		rspamd_config_get_module_opt (cfg, "spf", "spf_cache_size")) != NULL) {
		cache_size = ucl_obj_toint (value);
	}
	else {
		cache_size = DEFAULT_CACHE_SIZE;
	}
	if ((value =
		rspamd_config_get_module_opt (cfg, "spf",
		"spf_cache_expire")) != NULL) {
		cache_expire = ucl_obj_toint (value);
	}
	else {
		cache_expire = DEFAULT_CACHE_MAXAGE;
	}
	if ((value =
		rspamd_config_get_module_opt (cfg, "spf", "whitelist")) != NULL) {
		if (!rspamd_map_add (cfg, ucl_obj_tostring (value),
			"SPF whitelist", rspamd_radix_read, rspamd_radix_fin,
			(void **)&spf_module_ctx->whitelist_ip)) {
			radix_add_generic_iplist (ucl_obj_tostring (value),
				&spf_module_ctx->whitelist_ip);
		}
	}

	register_symbol (&cfg->cache,
		spf_module_ctx->symbol_fail,
		1,
		spf_symbol_callback,
		NULL);
	register_virtual_symbol (&cfg->cache, spf_module_ctx->symbol_softfail, 1);
	register_virtual_symbol (&cfg->cache, spf_module_ctx->symbol_neutral,  1);
	register_virtual_symbol (&cfg->cache, spf_module_ctx->symbol_allow,	   1);

	spf_module_ctx->spf_hash = rspamd_lru_hash_new (
			cache_size,
			cache_expire,
			g_free,
			spf_record_destroy);

	return res;
}

gint
spf_module_reconfig (struct rspamd_config *cfg)
{
	rspamd_mempool_delete (spf_module_ctx->spf_pool);
	radix_destroy_compressed (spf_module_ctx->whitelist_ip);
	memset (spf_module_ctx, 0, sizeof (*spf_module_ctx));
	spf_module_ctx->spf_pool = rspamd_mempool_new (
		rspamd_mempool_suggest_size ());

	return spf_module_config (cfg);
}

static gboolean
spf_check_element (struct spf_addr *addr, struct rspamd_task *task)
{
	gboolean res = FALSE;
	guint8 *s, *d, t;
	gchar *spf_result;
	const gchar *spf_message, *spf_symbol;
	guint nbits, addrlen;
	struct in_addr in4s, in4d;
	struct in6_addr in6s, in6d;
	GList *opts = NULL;

	/* Basic comparing algorithm */
	if ((addr->data.normal.ipv6 && task->from_addr.af == AF_INET6) ||
		(!addr->data.normal.ipv6 && task->from_addr.af == AF_INET)) {
		if (addr->data.normal.ipv6) {
			addrlen = sizeof (struct in6_addr);
			memcpy (&in6s, &addr->data.normal.d.in6,
				sizeof (struct in6_addr));
			memcpy (&in6d, &task->from_addr.addr.s6.sin6_addr,
				sizeof (struct in6_addr));
			s = (guint8 *)&in6s;
			d = (guint8 *)&in6d;
		}
		else {
			addrlen = sizeof (struct in_addr);
			memcpy (&in4s, &addr->data.normal.d.in4,
				sizeof (struct in_addr));
			memcpy (&in4d, &task->from_addr.addr.s4.sin_addr,
				sizeof (struct in_addr));
			s = (guint8 *)&in4s;
			d = (guint8 *)&in4d;
		}
		/* Move pointers to the less significant byte */
		t = 0x1;
		s += addrlen - 1;
		d += addrlen - 1;
		/* TODO: improve this cycle by masking by words */
		for (nbits = 0;
			nbits < addrlen * CHAR_BIT - addr->data.normal.mask;
			nbits++) {
			/* Skip bits from the beginning as we know that data is in network byte order */
			if (nbits != 0 && nbits % 8 == 0) {
				/* Move pointer to the next byte */
				s--;
				d--;
				t = 0x1;
			}
			*s |= t;
			*d |= t;
			t <<= 1;
		}
		if (addr->data.normal.ipv6) {
			res = memcmp (&in6d, &in6s, sizeof (struct in6_addr)) == 0;
		}
		else {
			res = memcmp (&in4d, &in4s, sizeof (struct in_addr)) == 0;
		}
	}
	else {
		if (addr->data.normal.addr_any) {
			res = TRUE;
		}
		else {
			res = FALSE;
		}
	}

	if (res) {
		spf_result = rspamd_mempool_strdup (task->task_pool, addr->spf_string);
		opts = g_list_prepend (opts, spf_result);
		switch (addr->mech) {
		case SPF_FAIL:
			spf_symbol = spf_module_ctx->symbol_fail;
			spf_message = "(SPF): spf fail";
			break;
		case SPF_SOFT_FAIL:
			spf_symbol = spf_module_ctx->symbol_softfail;
			spf_message = "(SPF): spf softfail";
			break;
		case SPF_NEUTRAL:
			spf_symbol = spf_module_ctx->symbol_neutral;
			spf_message = "(SPF): spf neutral";
			break;
		default:
			spf_symbol = spf_module_ctx->symbol_allow;
			spf_message = "(SPF): spf allow";
			break;
		}
		rspamd_task_insert_result (task,
				spf_symbol,
				1,
				opts);
		task->messages = g_list_prepend (task->messages, (gpointer)spf_message);
		return TRUE;
	}

	return FALSE;
}

static gboolean
spf_check_list (GList *list, struct rspamd_task *task)
{
	GList *cur;
	struct spf_addr *addr;

	cur = list;

	while (cur) {
		addr = cur->data;
		if (addr->is_list) {
			/* Recursive call */
			if (spf_check_list (addr->data.list, task)) {
				return TRUE;
			}
		}
		else {
			if (spf_check_element (addr, task)) {
				return TRUE;
			}
		}
		cur = g_list_next (cur);
	}

	return FALSE;
}

static void
spf_plugin_callback (struct spf_record *record, struct rspamd_task *task)
{
	GList *l;

	if (record && record->addrs && record->sender_domain) {

		if ((l =
			rspamd_lru_hash_lookup (spf_module_ctx->spf_hash,
			record->sender_domain, task->tv.tv_sec)) == NULL) {
			l = spf_record_copy (record->addrs);
			rspamd_lru_hash_insert (spf_module_ctx->spf_hash,
				g_strdup (record->sender_domain),
				l, task->tv.tv_sec, record->ttl);
		}
		spf_check_list (l, task);
	}
}


static void
spf_symbol_callback (struct rspamd_task *task, void *unused)
{
	gchar *domain;
	GList *l;

	if (radix_find_compressed_addr (spf_module_ctx->whitelist_ip,
			&task->from_addr) == RADIX_NO_VALUE) {
		domain = get_spf_domain (task);
		if (domain) {
			if ((l =
				rspamd_lru_hash_lookup (spf_module_ctx->spf_hash, domain,
				task->tv.tv_sec)) != NULL) {
				spf_check_list (l, task);
			}
			else if (!resolve_spf (task, spf_plugin_callback)) {
				msg_info ("cannot make spf request for [%s]", task->message_id);
			}
		}
	}
}

/*
 * Make a deep copy of list, note copy is REVERSED
 */
static GList *
spf_record_copy (GList *addrs)
{
	GList *cur, *newl = NULL;
	struct spf_addr *addr, *newa;

	cur = addrs;

	while (cur) {
		addr = cur->data;
		newa = g_malloc (sizeof (struct spf_addr));
		memcpy (newa, addr, sizeof (struct spf_addr));
		if (addr->is_list) {
			/* Recursive call */
			newa->data.list = spf_record_copy (addr->data.list);
		}
		else {
			if (addr->spf_string) {
				newa->spf_string = g_strdup (addr->spf_string);
			}
		}
		newl = g_list_prepend (newl, newa);
		cur = g_list_next (cur);
	}

	return newl;
}

/*
 * Destroy allocated spf list
 */


static void
spf_record_destroy (gpointer list)
{
	GList *cur = list;
	struct spf_addr *addr;

	while (cur) {
		addr = cur->data;
		if (addr->is_list) {
			spf_record_destroy (addr->data.list);
		}
		else {
			if (addr->spf_string) {
				g_free (addr->spf_string);
			}
		}
		g_free (addr);
		cur = g_list_next (cur);
	}

	g_list_free (list);
}