/* Copyright (c) 2002-2016 Pigeonhole authors, see the included COPYING file
 */

#include "login-common.h"
#include "base64.h"
#include "buffer.h"
#include "ioloop.h"
#include "istream.h"
#include "ostream.h"
#include "safe-memset.h"
#include "str.h"
#include "str-sanitize.h"
#include "auth-client.h"

#include "managesieve-parser.h"
#include "managesieve-quote.h"
#include "client.h"

#include "client-authenticate.h"
#include "managesieve-proxy.h"


const char *client_authenticate_get_capabilities
(struct client *client)
{
	const struct auth_mech_desc *mech;
	unsigned int i, count;
	bool first = TRUE;
	string_t *str;

	str = t_str_new(128);
	mech = sasl_server_get_advertised_mechs(client, &count);

	for (i = 0; i < count; i++) {
		/* Filter ANONYMOUS mechanism, ManageSieve has no use-case for it */
		if ( (mech[i].flags & MECH_SEC_ANONYMOUS) == 0 ) {
			if ( !first )
				str_append_c(str, ' ');
			else
				first = FALSE;

			str_append(str, mech[i].name);
		}
	}

	return str_c(str);
}

void managesieve_client_auth_result(struct client *client,
				   enum client_auth_result result,
				   const struct client_auth_reply *reply, const char *text)
{
	struct managesieve_client *msieve_client =
		(struct managesieve_client *)client;
	string_t *referral;

	switch (result) {
	case CLIENT_AUTH_RESULT_SUCCESS:
		/* nothing to be done for IMAP */
		break;
	case CLIENT_AUTH_RESULT_REFERRAL_SUCCESS:
	case CLIENT_AUTH_RESULT_REFERRAL_NOLOGIN:
		/* MANAGESIEVE referral

		   [nologin] referral host=.. [port=..] [destuser=..]
		   [reason=..]

		   NO [REFERRAL sieve://user;AUTH=mech@host:port/] "Can't login."
		   OK [...] "Logged in, but you should use this server instead."
		   .. [REFERRAL ..] Reason from auth server
		*/
		referral = t_str_new(128);
		str_printfa(referral, "REFERRAL sieve://%s;AUTH=%s@%s",
			    reply->destuser, client->auth_mech_name, reply->host);
		if ( reply->port != 4190 )
			str_printfa(referral, ":%u", reply->port);

		if ( result == CLIENT_AUTH_RESULT_REFERRAL_SUCCESS ) {
			client_send_okresp(client, str_c(referral), text);;
		} else {
			client_send_noresp(client, str_c(referral), text);
		}
		break;
	case CLIENT_AUTH_RESULT_ABORTED:
	case CLIENT_AUTH_RESULT_AUTHFAILED_REASON:
	case CLIENT_AUTH_RESULT_AUTHZFAILED:
		client_send_no(client, text);
		break;
	case CLIENT_AUTH_RESULT_TEMPFAIL:
		client_send_noresp(client, "TRYLATER", text);
		break;
	case CLIENT_AUTH_RESULT_SSL_REQUIRED:
		client_send_noresp(client, "ENCRYPT-NEEDED", text);
		break;
	case CLIENT_AUTH_RESULT_AUTHFAILED:
	default:
		client_send_no(client,  text);
		break;
	}

	msieve_client->auth_response_input = NULL;
	managesieve_parser_reset(msieve_client->parser);
}

void managesieve_client_auth_send_challenge
(struct client *client, const char *data)
{
	struct managesieve_client *msieve_client =
		(struct managesieve_client *) client;

	T_BEGIN {
		string_t *str = t_str_new(256);

		managesieve_quote_append_string(str, data, TRUE);
		str_append(str, "\r\n");

		client_send_raw_data(client, str_c(str), str_len(str));
	} T_END;

	msieve_client->auth_response_input = NULL;
	managesieve_parser_reset(msieve_client->parser);
}

static int managesieve_client_auth_read_response
(struct managesieve_client *msieve_client, bool initial, const char **error_r)
{
	struct client *client = &msieve_client->common;
	const struct managesieve_arg *args;
	const char *error;
	bool fatal;
	const unsigned char *data;
	size_t size;
	uoff_t resp_size;
	int ret;

	*error_r = NULL;

	if ( i_stream_read(client->input) == -1 ) {
		/* disconnected */
		client_destroy(client, "Disconnected");
		return -1;
	}

	if ( msieve_client->auth_response_input == NULL ) {

		if ( msieve_client->skip_line ) {
			if ( i_stream_next_line(client->input) == NULL )
				return 0;

			msieve_client->skip_line = FALSE;
		}

		switch ( managesieve_parser_read_args(msieve_client->parser, 0,
			MANAGESIEVE_PARSE_FLAG_STRING_STREAM, &args) ) {
		case -1:
			error = managesieve_parser_get_error(msieve_client->parser, &fatal);
			if (fatal) {
				client_send_bye(client, error);
				client_destroy(client, t_strconcat
					("Disconnected: parse error during auth: ", error, NULL));
			} else {
				*error_r = error;
			}
			msieve_client->skip_line = TRUE;
			return -1;

		case -2:
			/* not enough data */
			return 0;

		default:
			break;
		}

		if ( MANAGESIEVE_ARG_IS_EOL(&args[0]) ) {
			if (!initial) {
				*error_r = "Received empty AUTHENTICATE client response line.";
				msieve_client->skip_line = TRUE;
				return -1;
			}
			msieve_client->skip_line = TRUE;
			return 1;
		}

		if ( !managesieve_arg_get_string_stream
				(&args[0], &msieve_client->auth_response_input)
			|| !MANAGESIEVE_ARG_IS_EOL(&args[1]) ) {
			if ( !initial )
				*error_r = "Invalid AUTHENTICATE client response.";
			else
				*error_r = "Invalid AUTHENTICATE initial response.";
			msieve_client->skip_line = TRUE;
			return -1;
		}

		if ( i_stream_get_size
			(msieve_client->auth_response_input, FALSE, &resp_size) <= 0 )
			resp_size = 0;

		if (client->auth_response == NULL)
			client->auth_response = str_new(default_pool, I_MAX(resp_size+1, 256));
	}

	while ( (ret=i_stream_read_data
		(msieve_client->auth_response_input, &data, &size, 0) ) > 0 ) {

		if (str_len(client->auth_response) + size > LOGIN_MAX_AUTH_BUF_SIZE) {
			client_destroy(client, "Authentication response too large");
			return -1;
		}

		str_append_n(client->auth_response, data, size);
		i_stream_skip(msieve_client->auth_response_input, size);
	}

	if ( ret == 0 ) return 0;

	if ( msieve_client->auth_response_input->stream_errno != 0 ) {
		if ( !client->input->eof &&
			msieve_client->auth_response_input->stream_errno == EINVAL ) {
			msieve_client->skip_line = TRUE;
			*error_r = t_strconcat
				("Error in AUTHENTICATE response string: ",
					i_stream_get_error(msieve_client->auth_response_input), NULL);
			return -1;
		}

		client_destroy(client, "Disconnected");
		return -1;
	}

	if ( i_stream_next_line(client->input) == NULL )
		return 0;

	return 1;
}

void managesieve_client_auth_parse_response(struct client *client)
{
	struct managesieve_client *msieve_client =
		(struct managesieve_client *) client;
	const char *error = NULL;
	int ret;

	if ( (ret=managesieve_client_auth_read_response(msieve_client, FALSE, &error))
		< 0 ) {
		if ( error != NULL )
			client_auth_fail(client, error);
		return;
	}

	if ( ret == 0 ) return;

	if ( strcmp(str_c(client->auth_response), "*") == 0 ) {
		client_auth_abort(client);
		return;
	}

	client_auth_respond(client, str_c(client->auth_response));

	memset(str_c_modifiable(client->auth_response), 0,
	       str_len(client->auth_response));
}

int cmd_authenticate
(struct managesieve_client *msieve_client, const struct managesieve_arg *args)
{
	/* NOTE: This command's input is handled specially because the
	   SASL-IR can be large. */
	struct client *client = &msieve_client->common;
	const char *mech_name, *init_response;
	const char *error;
	int ret;

	if (!msieve_client->auth_mech_name_parsed) {
		i_assert(args != NULL);

		/* one mandatory argument: authentication mechanism name */
		if ( !managesieve_arg_get_string(&args[0], &mech_name) )
			return -1;

		if (*mech_name == '\0')
			return -1;

		/* Refuse the ANONYMOUS mechanism. */
		if ( strncasecmp(mech_name, "ANONYMOUS", 9) == 0 ) {
			client_send_no(client, "ANONYMOUS login is not allowed.");
			return 1;
		}

		i_free(client->auth_mech_name);
		client->auth_mech_name = i_strdup(mech_name);
		msieve_client->auth_mech_name_parsed = TRUE;

		msieve_client->auth_response_input = NULL;
		managesieve_parser_reset(msieve_client->parser);
	}

	msieve_client->skip_line = FALSE;
	if ( (ret=managesieve_client_auth_read_response(msieve_client, TRUE, &error))
		< 0 ) {
		if ( error != NULL ) {
			msieve_client->auth_mech_name_parsed = FALSE;
			client_send_no(client, error);
		}
		return 1;
	}

	if ( ret == 0 ) return 0;

	init_response = ( client->auth_response == NULL ? NULL :
		t_strdup(str_c(client->auth_response)) );
	msieve_client->auth_mech_name_parsed = FALSE;
	if ( (ret=client_auth_begin
		(client, t_strdup(client->auth_mech_name), init_response)) < 0 )
		return ret;

	msieve_client->cmd_finished = TRUE;
	return 0;
}