/*
 * NTLM and NTLMv2 authentication mechanism.
 *
 * Copyright (c) 2004 Andrey Panin <pazke@donpac.ru>
 *
 * 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.
 */

#include "common.h"
#include "mech.h"
#include "passdb.h"
#include "str.h"
#include "buffer.h"
#include "hex-binary.h"
#include "safe-memset.h"

#include "ntlm.h"

struct ntlm_auth_request {
	struct auth_request auth_request;

	pool_t pool;

	/* requested: */
	const unsigned char *challenge;

	/* received: */
	struct ntlmssp_response *response;
};

static void
lm_credentials_callback(const char *credentials,
			struct auth_request *auth_request)
{
	struct ntlm_auth_request *auth =
		(struct ntlm_auth_request *)auth_request;
	const unsigned char *client_response;
	unsigned char lm_response[LM_RESPONSE_SIZE];
	unsigned char hash[LM_HASH_SIZE];
	buffer_t *hash_buffer;
	int ret;

	if (credentials == NULL) {
		mech_auth_finish(auth_request, NULL, 0, FALSE);
		return;
	}

	hash_buffer = buffer_create_data(auth_request->pool,
					 hash, sizeof(hash));
	hex_to_binary(credentials, hash_buffer);

	client_response = ntlmssp_buffer_data(auth->response, lm_response);

	ntlmssp_v1_response(hash, auth->challenge, lm_response);

	ret = memcmp(lm_response, client_response, LM_RESPONSE_SIZE) == 0;

	mech_auth_finish(auth_request, NULL, 0, ret);
}

static void
ntlm_credentials_callback(const char *credentials,
			  struct auth_request *auth_request)
{
	struct ntlm_auth_request *auth =
		(struct ntlm_auth_request *)auth_request;
	const unsigned char *client_response;
	unsigned char hash[NTLMSSP_HASH_SIZE];
	unsigned int response_length;
	buffer_t *hash_buffer;
	int ret;

	if (credentials == NULL) {
		passdb->lookup_credentials(auth_request,
					   PASSDB_CREDENTIALS_LANMAN,
					   lm_credentials_callback);
		return;
	}

	hash_buffer = buffer_create_data(auth_request->pool,
					 hash, sizeof(hash));
	hex_to_binary(credentials, hash_buffer);

	response_length = ntlmssp_buffer_length(auth->response, ntlm_response);
	client_response = ntlmssp_buffer_data(auth->response, ntlm_response);

	if (response_length > NTLMSSP_RESPONSE_SIZE) {
		unsigned char ntlm_v2_response[NTLMSSP_V2_RESPONSE_SIZE];
		const unsigned char *blob =
			client_response + NTLMSSP_V2_RESPONSE_SIZE;

		/*
		 * Authentication target == NULL because we are acting
		 * as a standalone server, not as NT domain member.
		 */
		ntlmssp_v2_response(auth_request->user, NULL,
				    hash, auth->challenge, blob,
				    response_length - NTLMSSP_V2_RESPONSE_SIZE,
				    ntlm_v2_response);

		ret = memcmp(ntlm_v2_response, client_response,
			     NTLMSSP_V2_RESPONSE_SIZE) == 0;
	} else {
		unsigned char ntlm_response[NTLMSSP_RESPONSE_SIZE];

		ntlmssp_v1_response(hash, auth->challenge, ntlm_response);

		ret = memcmp(ntlm_response, client_response,
			     NTLMSSP_RESPONSE_SIZE) == 0;
	}

	mech_auth_finish(auth_request, NULL, 0, ret);
}

static int
mech_ntlm_auth_continue(struct auth_request *auth_request,
			const unsigned char *data, size_t data_size,
			mech_callback_t *callback)
{
	struct ntlm_auth_request *auth =
		(struct ntlm_auth_request *)auth_request;
	struct auth_client_request_reply reply;
	const char *error;

	auth_request->callback = callback;

	if (!auth->challenge) {
		const struct ntlmssp_request *request =
			(struct ntlmssp_request *)data;
		const struct ntlmssp_challenge *message;
		size_t message_size;

		if (!ntlmssp_check_request(request, data_size, &error)) {
			if (verbose) {
				i_info("ntlm(%s): invalid NTLM request, %s",
				       get_log_prefix(auth_request),
				       error);
			}
			mech_auth_finish(auth_request, NULL, 0, FALSE);
			return TRUE;
		}

		message = ntlmssp_create_challenge(auth->pool, request,
						   &message_size);
		auth->challenge = message->challenge;

		mech_init_auth_client_reply(&reply);
		reply.id = auth_request->id;
		reply.result = AUTH_CLIENT_RESULT_CONTINUE;

		reply.reply_idx = 0;
		reply.data_size = message_size;
		callback(&reply, message, auth_request->conn);
	} else {
		const struct ntlmssp_response *response =
			(struct ntlmssp_response *)data;
		char *username;

		if (!ntlmssp_check_response(response, data_size, &error)) {
			if (verbose) {
				i_info("ntlm(%s): invalid NTLM response, %s",
				       get_log_prefix(auth_request),
				       error);
			}
			mech_auth_finish(auth_request, NULL, 0, FALSE);
			return TRUE;
		}

		auth->response = p_malloc(auth->pool, data_size);
		memcpy(auth->response, response, data_size);

		username = p_strdup(auth_request->pool,
				    ntlmssp_t_str(auth->response, user));

		if (!mech_is_valid_username(username)) {
			if (verbose) {
				i_info("ntlm(%s): invalid username",
				       get_log_prefix(auth_request));
			}
			mech_auth_finish(auth_request, NULL, 0, FALSE);
			return TRUE;
		}

		auth_request->user = username;

		passdb->lookup_credentials(auth_request,
					   PASSDB_CREDENTIALS_NTLM,
					   ntlm_credentials_callback);
	}

	return TRUE;
}

static int
mech_ntlm_auth_initial(struct auth_request *auth_request,
		       struct auth_client_request_new *request,
		       const unsigned char *data __attr_unused__,
		       mech_callback_t *callback)
{
	struct auth_client_request_reply reply;

	mech_init_auth_client_reply(&reply);
	reply.id = request->id;
	reply.result = AUTH_CLIENT_RESULT_CONTINUE;

	reply.reply_idx = 0;
	reply.data_size = 0;
	callback(&reply, "", auth_request->conn);

	return TRUE;
}

static void
mech_ntlm_auth_free(struct auth_request *auth_request)
{
	pool_unref(auth_request->pool);
}

static struct auth_request *mech_ntlm_auth_new(void)
{
	struct ntlm_auth_request *auth;
	pool_t pool;

	pool = pool_alloconly_create("ntlm_auth_request", 256);
	auth = p_new(pool, struct ntlm_auth_request, 1);
	auth->pool = pool;

	auth->auth_request.refcount = 1;
	auth->auth_request.pool = pool;
	auth->auth_request.auth_initial = mech_ntlm_auth_initial;
	auth->auth_request.auth_continue = mech_ntlm_auth_continue;
	auth->auth_request.auth_free = mech_ntlm_auth_free;

	return &auth->auth_request;
}

const struct mech_module mech_ntlm = {
	"NTLM",

	MEMBER(plaintext) FALSE,
	MEMBER(advertise) TRUE,

	MEMBER(passdb_need_plain) FALSE,
	MEMBER(passdb_need_credentials) TRUE,

	mech_ntlm_auth_new,
};