/*
 * maxminddb.c - MaxMind GeoIP2 dlfunc for Exim
 * https://mta.org.ua/exim-4.88-conf/dlfunc/maxminddb/maxminddb.c
 *
 * Copyright (C) 2018 Victor Ustugov <corvax+dlfunc@mta.org.ua>
 *
 * This library 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 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library 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 library; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include <errno.h>
#include <maxminddb.h>
#include <stdlib.h>
#include <string.h>

/* libmaxmind utils: */
#include "maxminddb-compat-util.h"

/* Exim4 dlfunc API header: */
//#include "local_scan.h"
#include "exim.h"

/*****************************************************************************
* Configuration settings:                                                    *
*****************************************************************************/

/* default code returned when country is unknown: */
#define RESULT_UNKNOWN		US"--"

/* default code returned on lookup failures: */
#define RESULT_LOOKUP_FAILED	US"--"

/*************************************************
*         Case-independent strcmp() function     *
*         from Exim sources                      *
*************************************************/

/*
Arguments:
  s         first string
  t         second string

Returns:    < 0, = 0, or > 0, according to the comparison
*/

int
strcmpic(const uschar *s, const uschar *t)
{
while (*s != 0)
  {
  int c = tolower(*s++) - tolower(*t++);
  if (c != 0) return c;
  }
return *t;
}


/*****************************************************************************
* Country code lookup function:                                              *
*****************************************************************************/

int maxminddb(uschar **yield, int argc, uschar *argv[])
{
	char *filename = (char *)argv[0];
	char *ip_address = (char *)argv[1];
	int defer_ok = 0;
	int status;
	MMDB_s mmdb;

	if (argc < 2) {
		debug_printf("maxminddb dlfunc: Invalid number of arguments\n");
		*yield = string_copy(US"Invalid number of arguments");
		return ERROR;
	}

	if (argc < 3) {
		defer_ok = 0;
	} else if (
		(strcmpic(argv[2], US"1") == 0)
		|| (strcmpic(argv[2], US"yes") == 0)
		|| (strcmpic(argv[2], US"true") == 0)
		|| (strcmpic(argv[2], US"defer_ok") == 0)
	) {
		defer_ok = 1;
	} else {
		defer_ok = 0;
	}
	debug_printf("maxminddb dlfunc: defer_ok: %d\n", defer_ok);


	status = MMDB_open(filename, MMDB_MODE_MMAP, &mmdb);
	if (status != MMDB_SUCCESS) {
		if (defer_ok) {
			if (status == MMDB_IO_ERROR) {
				debug_printf("maxminddb dlfunc: IO error: %s\n", strerror(errno));
				log_write(0, LOG_PANIC, "maxminddb dlfunc: IO error: %s", strerror(errno));
			} else {
				debug_printf("maxminddb dlfunc: Can't open %s - %s\n", filename, MMDB_strerror(status));
				log_write(0, LOG_PANIC, "maxminddb dlfunc: Can't open %s - %s", filename, MMDB_strerror(status));
			}
			goto LOOKUP_FAILED_DEFER_OK;
		} else {
			if (status == MMDB_IO_ERROR) {
				*yield = string_sprintf("IO error: %s", strerror(errno));
			} else {
				*yield = string_sprintf("Can't open %s - %s", filename, MMDB_strerror(status));
			}
			return ERROR;
		}
	}

	int gai_error, mmdb_error;

	MMDB_lookup_result_s result = MMDB_lookup_string(&mmdb, ip_address, &gai_error, &mmdb_error);
	if (gai_error != 0) {
		if (defer_ok) {
			debug_printf("maxminddb dlfunc: Error from getaddrinfo for %s - %s\n", ip_address, gai_strerror(gai_error));
			log_write(0, LOG_PANIC, "maxminddb dlfunc: Error from getaddrinfo for %s - %s", ip_address, gai_strerror(gai_error));
			goto LOOKUP_FAILED_DEFER_OK;
		} else {
			*yield = string_sprintf("Error from getaddrinfo for %s - %s", ip_address, gai_strerror(gai_error));
			return ERROR;
		}
	}
	if ( mmdb_error != MMDB_SUCCESS) {
		if (defer_ok) {
			debug_printf("maxminddb dlfunc: Got an error from libmaxminddb: %s\n", MMDB_strerror(mmdb_error));
			log_write(0, LOG_PANIC, "maxminddb dlfunc: Got an error from libmaxminddb: %s", MMDB_strerror(mmdb_error));
			goto LOOKUP_FAILED_DEFER_OK;
		} else {
			*yield = string_sprintf("Got an error from libmaxminddb: %s", MMDB_strerror(mmdb_error));
			return ERROR;
		}
	}

	MMDB_entry_data_list_s *entry_data_list = NULL;
	MMDB_entry_data_s entry_data;
	char *country = NULL;
	char *continent = NULL;

	if (result.found_entry) {
		status = MMDB_get_value(&result.entry, &entry_data, "registered_country", "iso_code", NULL);
		if (status == MMDB_LOOKUP_PATH_DOES_NOT_MATCH_DATA_ERROR) {
			debug_printf("maxminddb dlfunc: Got an error looking up the entry data for country ISO code - %s; Try to find \"country\" ISO code instead of \"registered_country\" ISO code\n", MMDB_strerror(status));
			status = MMDB_get_value(&result.entry, &entry_data, "country", "iso_code", NULL);
		}
		if (status != MMDB_SUCCESS) {
			if (defer_ok) {
				debug_printf("maxminddb dlfunc: Got an error looking up the entry data for country ISO code - %s\n", MMDB_strerror(status));
				log_write(0, LOG_PANIC, "maxminddb dlfunc: Got an error looking up the entry data for country ISO code - %s", MMDB_strerror(status));
				goto LOOKUP_FAILED_DEFER_OK_MMDB_CLOSE;
			} else {
				*yield = string_sprintf("Got an error looking up the entry data for country ISO code - %s\n", MMDB_strerror(status));
				goto LOOKUP_FAILED_MMDB_CLOSE;
			}
		}
		if (entry_data.has_data) {
			if (entry_data.type == MMDB_DATA_TYPE_UTF8_STRING) {
				country = mmdb_strndup((char *)entry_data.utf8_string, entry_data.data_size);
				if (country == NULL) {
					if (defer_ok) {
						debug_printf("maxminddb dlfunc: Got an memory error - %s\n", MMDB_strerror(MMDB_OUT_OF_MEMORY_ERROR));
						log_write(0, LOG_PANIC, "maxminddb dlfunc: Got an memory error - %s", MMDB_strerror(MMDB_OUT_OF_MEMORY_ERROR));
						goto LOOKUP_FAILED_DEFER_OK_MMDB_CLOSE;
					} else {
						*yield = string_sprintf("Got an memory error - %s\n", MMDB_strerror(MMDB_OUT_OF_MEMORY_ERROR));
						goto LOOKUP_FAILED_MMDB_CLOSE;
					}
				}
				debug_printf("maxminddb dlfunc: country is found: %s\n", country);
			} else {
				debug_printf("maxminddb dlfunc: Unexpected data type for country ISO code entry for this IP address (%s) was found\n", ip_address);
				log_write(0, LOG_MAIN, "maxminddb dlfunc: Unexpected data type for country ISO code entry for this IP address (%s) was found", ip_address);
			}
		} else {
			debug_printf("maxminddb dlfunc: No country ISO code entry for this IP address (%s) was found\n", ip_address);
			log_write(0, LOG_MAIN, "maxminddb dlfunc: No country ISO code entry for this IP address (%s) was found", ip_address);
		}

		status = MMDB_get_value(&result.entry, &entry_data, "continent", "code", NULL);
		if (status != MMDB_SUCCESS) {
			if (defer_ok) {
				debug_printf("maxminddb dlfunc: Got an error looking up the entry data for continent code - %s\n", MMDB_strerror(status));
				log_write(0, LOG_PANIC, "maxminddb dlfunc: Got an error looking up the entry data for continent code - %s", MMDB_strerror(status));
				goto LOOKUP_FAILED_DEFER_OK_MMDB_CLOSE;
			} else {
				*yield = string_sprintf("Got an error looking up the entry data for continent code - %s\n", MMDB_strerror(status));
				goto LOOKUP_FAILED_MMDB_CLOSE;
			}
		}
		if (entry_data.has_data) {
			if (entry_data.type == MMDB_DATA_TYPE_UTF8_STRING) {
				continent = mmdb_strndup((char *)entry_data.utf8_string, entry_data.data_size);
				if (continent == NULL) {
					if (defer_ok) {
						debug_printf("maxminddb dlfunc: Got an memory error - %s\n", MMDB_strerror(MMDB_OUT_OF_MEMORY_ERROR));
						log_write(0, LOG_PANIC, "maxminddb dlfunc: Got an memory error - %s", MMDB_strerror(MMDB_OUT_OF_MEMORY_ERROR));
						goto LOOKUP_FAILED_DEFER_OK_MMDB_CLOSE;
					} else {
						*yield = string_sprintf("Got an memory error - %s\n", MMDB_strerror(MMDB_OUT_OF_MEMORY_ERROR));
						goto LOOKUP_FAILED_MMDB_CLOSE;
					}
				}
				debug_printf("maxminddb dlfunc: continent is found: %s\n", continent);
			} else {
				debug_printf("maxminddb dlfunc: Unexpected data type for continent code entry for this IP address (%s) was found\n", ip_address);
				log_write(0, LOG_MAIN, "maxminddb dlfunc: Unexpected data type for continent code entry for this IP address (%s) was found", ip_address);
			}
		} else {
			debug_printf("maxminddb dlfunc: No continent code entry for this IP address (%s) was found\n", ip_address);
			log_write(0, LOG_MAIN, "maxminddb dlfunc: No continent code entry for this IP address (%s) was found", ip_address);
		}
	} else {
		debug_printf("maxminddb dlfunc: No entry for this IP address (%s) was found\n", ip_address);
		log_write(0, LOG_MAIN, "maxminddb dlfunc: No entry for this IP address (%s) was found", ip_address);
	}

	MMDB_close(&mmdb);
	*yield = string_sprintf("country=\"%s\" continent=\"%s\"", (country == NULL ? (char *)RESULT_UNKNOWN : country), (continent == NULL ? (char *)RESULT_UNKNOWN : continent));
	if (country != NULL) free(country);
	if (continent != NULL) free(continent);
	return OK;

LOOKUP_FAILED_DEFER_OK_MMDB_CLOSE:
	MMDB_close(&mmdb);
LOOKUP_FAILED_DEFER_OK:
	*yield = string_sprintf("country=\"%s\" continent=\"%s\"", RESULT_LOOKUP_FAILED, RESULT_LOOKUP_FAILED);
	if (country != NULL) free(country);
	if (continent != NULL) free(continent);
	return OK;

LOOKUP_FAILED_MMDB_CLOSE:
	MMDB_close(&mmdb);
	if (country != NULL) free(country);
	if (continent != NULL) free(continent);
	return ERROR;
}