/*
 *  authd.c: An interface to authd.
 *  (based somewhat on ircd-ratbox dns.c)
 *
 *  Copyright (C) 2005 Aaron Sethman <androsyn@ratbox.org>
 *  Copyright (C) 2005-2012 ircd-ratbox development team
 *  Copyright (C) 2016 William Pitcock <nenolod@dereferenced.org>
 *
 *  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 "stdinc.h"
#include "rb_lib.h"
#include "client.h"
#include "ircd_defs.h"
#include "parse.h"
#include "authd.h"
#include "match.h"
#include "logger.h"
#include "s_conf.h"
#include "s_stats.h"
#include "client.h"
#include "packet.h"
#include "hash.h"
#include "send.h"
#include "numeric.h"
#include "msg.h"
#include "dns.h"

static int start_authd(void);
static void parse_authd_reply(rb_helper * helper);
static void restart_authd_cb(rb_helper * helper);
static EVH timeout_dead_authd_clients;

rb_helper *authd_helper;
static char *authd_path;

uint32_t cid;
static rb_dictionary *cid_clients;
static struct ev_entry *timeout_ev;

rb_dictionary *bl_stats;

static int
start_authd(void)
{
	char fullpath[PATH_MAX + 1];
#ifdef _WIN32
	const char *suffix = ".exe";
#else
	const char *suffix = "";
#endif
	if(authd_path == NULL)
	{
		snprintf(fullpath, sizeof(fullpath), "%s%cauthd%s", ircd_paths[IRCD_PATH_LIBEXEC], RB_PATH_SEPARATOR, suffix);

		if(access(fullpath, X_OK) == -1)
		{
			snprintf(fullpath, sizeof(fullpath), "%s%cbin%cauthd%s",
				 ConfigFileEntry.dpath, RB_PATH_SEPARATOR, RB_PATH_SEPARATOR, suffix);
			if(access(fullpath, X_OK) == -1)
			{
				ierror("Unable to execute authd in %s or %s/bin",
					ircd_paths[IRCD_PATH_LIBEXEC], ConfigFileEntry.dpath);
				sendto_realops_snomask(SNO_GENERAL, L_ALL,
						       "Unable to execute authd in %s or %s/bin",
						       ircd_paths[IRCD_PATH_LIBEXEC], ConfigFileEntry.dpath);
				return 1;
			}

		}

		authd_path = rb_strdup(fullpath);
	}

	if(cid_clients == NULL)
		cid_clients = rb_dictionary_create("authd cid to uid mapping", rb_uint32cmp);

	if(bl_stats == NULL)
		bl_stats = rb_dictionary_create("blacklist statistics", strcasecmp);

	if(timeout_ev == NULL)
		timeout_ev = rb_event_addish("timeout_dead_authd_clients", timeout_dead_authd_clients, NULL, 1);

	authd_helper = rb_helper_start("authd", authd_path, parse_authd_reply, restart_authd_cb);

	if(authd_helper == NULL)
	{
		ierror("Unable to start authd helper: %s", strerror(errno));
		sendto_realops_snomask(SNO_GENERAL, L_ALL, "Unable to start authd helper: %s", strerror(errno));
		return 1;
	}
	ilog(L_MAIN, "authd helper started");
	sendto_realops_snomask(SNO_GENERAL, L_ALL, "authd helper started");
	rb_helper_run(authd_helper);
	return 0;
}

static inline uint32_t
str_to_cid(const char *str)
{
	long lcid = strtol(str, NULL, 16);

	if(lcid > UINT32_MAX || lcid <= 0)
	{
		iwarn("authd sent us back a bad client ID: %lx", lcid);
		restart_authd();
		return 0;
	}

	return (uint32_t)lcid;
}

static inline struct Client *
cid_to_client(uint32_t cid, bool delete)
{
	struct Client *client_p;

	if(delete)
		client_p = rb_dictionary_delete(cid_clients, RB_UINT_TO_POINTER(cid));
	else
		client_p = rb_dictionary_retrieve(cid_clients, RB_UINT_TO_POINTER(cid));

	if(client_p == NULL)
	{
		iwarn("authd sent us back a bad client ID: %ux", cid);
		restart_authd();
		return NULL;
	}

	return client_p;
}

static inline struct Client *
str_cid_to_client(const char *str, bool delete)
{
	uint32_t cid = str_to_cid(str);

	if(cid == 0)
		return NULL;

	return cid_to_client(cid, delete);
}

static void
parse_authd_reply(rb_helper * helper)
{
	ssize_t len;
	int parc;
	char authdBuf[READBUF_SIZE];
	char *parv[MAXPARA + 1];
	struct Client *client_p;

	while((len = rb_helper_read(helper, authdBuf, sizeof(authdBuf))) > 0)
	{
		parc = rb_string_to_array(authdBuf, parv, MAXPARA+1);

		switch (*parv[0])
		{
		case 'A':	/* Accepted a client */
			if(parc != 4)
			{
				iwarn("authd sent a result with wrong number of arguments: got %d", parc);
				restart_authd();
				return;
			}

			/* cid to uid (retrieve and delete) */
			if((client_p = str_cid_to_client(parv[1], true)) == NULL)
				return;

			authd_accept_client(client_p, parv[2], parv[3]);
			break;
		case 'R':	/* Reject client */
			if(parc != 7)
			{
				iwarn("authd sent us a result with wrong number of arguments: got %d", parc);
				restart_authd();
				return;
			}

			/* cid to uid (retrieve and delete) */
			if((client_p = str_cid_to_client(parv[1], true)) == NULL)
				return;

			authd_reject_client(client_p, parv[3], parv[4], toupper(*parv[2]), parv[5], parv[6]);
			break;
		case 'N':	/* Notice to client */
			if(parc != 3)
			{
				iwarn("authd sent us a result with wrong number of arguments: got %d", parc);
				restart_authd();
				return;
			}

			if((client_p = str_cid_to_client(parv[1], false)) == NULL)
				return;

			sendto_one_notice(client_p, ":%s", parv[2]);
			break;
		case 'E':	/* DNS Result */
			if(parc != 5)
			{
				iwarn("authd sent a result with wrong number of arguments: got %d", parc);
				restart_authd();
				return;
			}

			dns_results_callback(parv[1], parv[2], parv[3], parv[4]);
			break;
		case 'W':	/* Oper warning */
			if(parc != 3)
			{
				iwarn("authd sent a result with wrong number of arguments: got %d", parc);
				restart_authd();
				return;
			}

			switch(*parv[2])
			{
			case 'D':	/* Debug */
				sendto_realops_snomask(SNO_DEBUG, L_ALL, "authd debug: %s", parv[3]);
				idebug("authd: %s", parv[3]);
				break;
			case 'I':	/* Info */
				sendto_realops_snomask(SNO_GENERAL, L_ALL, "authd info: %s", parv[3]);
				inotice("authd: %s", parv[3]);
				break;
			case 'W':	/* Warning */
				sendto_realops_snomask(SNO_GENERAL, L_ALL, "authd WARNING: %s", parv[3]);
				iwarn("authd: %s", parv[3]);
				break;
			case 'C':	/* Critical (error) */
				sendto_realops_snomask(SNO_GENERAL, L_ALL, "authd CRITICAL: %s", parv[3]);
				ierror("authd: %s", parv[3]);
				break;
			default:	/* idk */
				sendto_realops_snomask(SNO_GENERAL, L_ALL, "authd sent us an unknown oper notice type (%s): %s", parv[2], parv[3]);
				ilog(L_MAIN, "authd unknown oper notice type (%s): %s", parv[2], parv[3]);
				break;
			}

			/* NOTREACHED */
			break;
		case 'X':	/* Stats error */
		case 'Y':	/* Stats reply */
		case 'Z':	/* End of stats reply */
			if(parc < 3)
			{
				iwarn("authd sent a result with wrong number of arguments: got %d", parc);
				restart_authd();
				return;
			}

			/* Select by type */
			switch(*parv[2])
			{
			case 'D':
				/* parv[0] conveys status */
				if(parc < 4)
				{
					iwarn("authd sent a result with wrong number of arguments: got %d", parc);
					restart_authd();
					return;
				}
				dns_stats_results_callback(parv[1], parv[0], parc - 3, (const char **)&parv[3]);
				break;
			default:
				break;
			}
			break;
		default:
			break;
		}
	}
}

void
init_authd(void)
{
	if(start_authd())
	{
		ierror("Unable to start authd helper: %s", strerror(errno));
		exit(0);
	}
}

void
configure_authd(void)
{
	/* These will do for now */
	set_authd_timeout("ident_timeout", GlobalSetOptions.ident_timeout);
	set_authd_timeout("rdns_timeout", ConfigFileEntry.connect_timeout);
	set_authd_timeout("rbl_timeout", ConfigFileEntry.connect_timeout);
	ident_check_enable(!ConfigFileEntry.disable_auth);
}

static void
restart_authd_cb(rb_helper * helper)
{
	rb_dictionary_iter iter;
	struct Client *client_p;

	iwarn("authd: restart_authd_cb called, authd died?");
	sendto_realops_snomask(SNO_GENERAL, L_ALL, "authd: restart_authd_cb called, authd died?");

	if(helper != NULL)
	{
		rb_helper_close(helper);
		authd_helper = NULL;
	}

	RB_DICTIONARY_FOREACH(client_p, &iter, cid_clients)
	{
		/* Abort any existing clients */
		authd_abort_client(client_p);
	}

	start_authd();
}

void
restart_authd(void)
{
	restart_authd_cb(authd_helper);
}

void
rehash_authd(void)
{
	rb_helper_write(authd_helper, "R");
	configure_authd();
}

void
check_authd(void)
{
	if(authd_helper == NULL)
		restart_authd();
}

static inline uint32_t
generate_cid(void)
{
	if(++cid == 0)
		cid = 1;

	return cid;
}

/* Basically when this is called we begin handing off the client to authd for
 * processing. authd "owns" the client until processing is finished, or we
 * timeout from authd. authd will make a decision whether or not to accept the
 * client, but it's up to other parts of the code (for now) to decide if we're
 * gonna accept the client and ignore authd's suggestion.
 *
 * --Elizafox
 */
void
authd_initiate_client(struct Client *client_p)
{
	char client_ipaddr[HOSTIPLEN+1];
	char listen_ipaddr[HOSTIPLEN+1];
	uint16_t client_port, listen_port;
	uint32_t authd_cid;

	if(client_p->preClient == NULL || client_p->preClient->authd_cid != 0)
		return;

	authd_cid = client_p->preClient->authd_cid = generate_cid();

	/* Collisions are extremely unlikely, so disregard the possibility */
	rb_dictionary_add(cid_clients, RB_UINT_TO_POINTER(authd_cid), client_p);

	/* Retrieve listener and client IP's */
	rb_inet_ntop_sock((struct sockaddr *)&client_p->preClient->lip, listen_ipaddr, sizeof(listen_ipaddr));
	rb_inet_ntop_sock((struct sockaddr *)&client_p->localClient->ip, client_ipaddr, sizeof(client_ipaddr));

	/* Retrieve listener and client ports */
	listen_port = ntohs(GET_SS_PORT(&client_p->preClient->lip));
	client_port = ntohs(GET_SS_PORT(&client_p->localClient->ip));

	/* Add a bit of a fudge factor... */
	client_p->preClient->authd_timeout = rb_current_time() + ConfigFileEntry.connect_timeout + 10;

	rb_helper_write(authd_helper, "C %x %s %hu %s %hu", authd_cid, listen_ipaddr, listen_port, client_ipaddr, client_port);
}

/* When this is called we have a decision on client acceptance.
 *
 * After this point authd no longer "owns" the client.
 */
static inline void
authd_decide_client(struct Client *client_p, const char *ident, const char *host, bool accept, char cause, const char *data, const char *reason)
{
	if(client_p->preClient == NULL || client_p->preClient->authd_cid == 0)
		return;

	if(*ident != '*')
	{
		rb_strlcpy(client_p->username, ident, sizeof(client_p->username));
		ServerStats.is_asuc++;
	}
	else
		ServerStats.is_abad++; /* s_auth used to do this, stay compatible */

	if(*host != '*')
		rb_strlcpy(client_p->host, host, sizeof(client_p->host));

	client_p->preClient->authd_accepted = accept;
	client_p->preClient->authd_cause = cause;
	client_p->preClient->authd_data = (data == NULL ? NULL : rb_strdup(data));
	client_p->preClient->authd_reason = (reason == NULL ? NULL : rb_strdup(reason));

	rb_dictionary_delete(cid_clients, RB_UINT_TO_POINTER(client_p->preClient->authd_cid));
	client_p->preClient->authd_cid = 0;

	/*
	 * When a client has auth'ed, we want to start reading what it sends
	 * us. This is what read_packet() does.
	 *     -- adrian
	 *
	 * Above comment was originally in s_auth.c, but moved here with below code.
	 * --Elizafox
	 */
	rb_dlinkAddTail(client_p, &client_p->node, &global_client_list);
	read_packet(client_p->localClient->F, client_p);
}

/* Convenience function to accept client */
void
authd_accept_client(struct Client *client_p, const char *ident, const char *host)
{
	authd_decide_client(client_p, ident, host, true, '\0', NULL, NULL);
}

/* Convenience function to reject client */
void
authd_reject_client(struct Client *client_p, const char *ident, const char *host, char cause, const char *data, const char *reason)
{
	authd_decide_client(client_p, ident, host, false, cause, data, reason);
}

void
authd_abort_client(struct Client *client_p)
{
	if(client_p == NULL || client_p->preClient == NULL)
		return;

	if(client_p->preClient->authd_cid == 0)
		return;

	rb_dictionary_delete(cid_clients, RB_UINT_TO_POINTER(client_p->preClient->authd_cid));

	if(authd_helper != NULL)
		rb_helper_write(authd_helper, "E %x", client_p->preClient->authd_cid);

	/* XXX should we blindly allow like this? */
	authd_accept_client(client_p, "*", "*");
	client_p->preClient->authd_cid = 0;
}

static void
timeout_dead_authd_clients(void *notused __unused)
{
	rb_dictionary_iter iter;
	struct Client *client_p;

	RB_DICTIONARY_FOREACH(client_p, &iter, cid_clients)
	{
		if(client_p->preClient->authd_timeout < rb_current_time())
			authd_abort_client(client_p);
	}
}

/* Turn a cause char (who rejected us) into the name of the provider */
const char *
get_provider_string(char cause)
{
	switch(cause)
	{
	case 'B':
		return "Blacklist";
	case 'D':
		return "rDNS";
	case 'I':
		return "Ident";
	default:
		return "Unknown";
	}
}

/* Send a new blacklist to authd */
void
add_blacklist(const char *host, const char *reason, uint8_t iptype, rb_dlink_list *filters)
{
	rb_dlink_node *ptr;
	struct blacklist_stats *stats = rb_malloc(sizeof(struct blacklist_stats));
	char filterbuf[BUFSIZE] = "*";
	size_t s = 0;

	/* Build a list of comma-separated values for authd.
	 * We don't check for validity - do it elsewhere.
	 */
	RB_DLINK_FOREACH(ptr, filters->head)
	{
		char *filter = ptr->data;
		size_t filterlen = strlen(filter) + 1;

		if(s + filterlen > sizeof(filterbuf))
			break;

		snprintf(&filterbuf[s], sizeof(filterbuf) - s, "%s,", filter);

		s += filterlen;
	}

	if(s)
		filterbuf[s - 1] = '\0';

	stats->iptype = iptype;
	stats->hits = 0;
	rb_dictionary_add(bl_stats, host, stats);

	rb_helper_write(authd_helper, "O rbl %s %hhu %s :%s", host, iptype, filterbuf, reason);
}

/* Delete a blacklist */
void
del_blacklist(const char *host)
{
	rb_dictionary_delete(bl_stats, host);

	rb_helper_write(authd_helper, "O rbl_del %s", host);
}

/* Delete all the blacklists */
void
del_blacklist_all(void)
{
	struct blacklist_stats *stats;
	rb_dictionary_iter iter;

	RB_DICTIONARY_FOREACH(stats, &iter, bl_stats)
	{
		rb_free(stats);
		rb_dictionary_delete(bl_stats, iter.cur->key);
	}

	rb_helper_write(authd_helper, "O rbl_del_all");
}

/* Adjust an authd timeout value */
bool
set_authd_timeout(const char *key, int timeout)
{
	if(timeout <= 0)
		return false;

	rb_helper_write(authd_helper, "O %s %d", key, timeout);
	return true;
}

/* Enable identd checks */
void
ident_check_enable(bool enabled)
{
	rb_helper_write(authd_helper, "O ident_enabled %d", enabled ? 1 : 0);
}

/* Create an OPM listener */
void
create_opm_listener(const char *ip, uint16_t port)
{
	rb_helper_write(authd_helper, "O opm_listener %s %hu", ip, port);
}

/* Disable all OPM scans */
void
opm_check_enable(bool enabled)
{
	rb_helper_write(authd_helper, "O opm_enable %d", enabled ? 1 : 0);
}

/* Create an OPM proxy scanner */
void
create_opm_proxy_scanner(const char *type, uint16_t port)
{
	rb_helper_write(authd_helper, "O opm_scanner %s %hu", type, port);
}