/*
  Copyright (c) 2015, Kristof Stahl <stahl@itsc.uni-luebeck.de>
  Copyright (c) 2015, Matthias Schiffer <mschiffer@universe-factory.net>
  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice,
       this list of conditions and the following disclaimer.
    2. 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER OR CONTRIBUTORS 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.
*/


/*
  Helpful pages:

  http://www.linux-pam.org/Linux-PAM-html/mwg-expected-of-module-auth.html
  http://www.linux-pam.org/Linux-PAM-html/mwg-expected-by-module-item.html
  http://www.linux-pam.org/Linux-PAM-html/mwg-see-programming-libs.html
  some (bad) example.. https://github.com/beatgammit/simple-pam/blob/master/src/mypam.c

  https://developer.gnome.org/libnm-glib/0.9/
  https://developer.gnome.org/libnm-util/0.9/
*/

#define PAM_SM_AUTH

#ifdef TEST

#include <stdio.h>

#endif

#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <sys/types.h>
#include <sys/wait.h>

#include <security/pam_modules.h>

#include <nm-client.h>
#include <nm-remote-settings.h>
#include <nm-setting-connection.h>
#include <nm-setting-wireless.h>
#include <nm-setting-wireless-security.h>
#include <nm-setting-8021x.h>
#include <nm-setting-ip4-config.h>
#include <nm-setting-ip6-config.h>


#define TIMEOUT 10
#define CONNECTION_ID "UzL-Wlan"
#define CONNECTION_UUID "af7b7f0b-3e09-442e-8841-f7d7482fa7b0"

#define CONNECTION_SSID "UzL-Wlan"
#define CONNECTION_AUTH_ALG "open"
#define CONNECTION_KEY_MGMT "wpa-eap"
#define CONNECTION_EAP "ttls"
#define CONNECTION_PHASE2_AUTHEAP "mschapv2"


static GByteArray * string_to_byte_array(const char *str) {
	size_t len = strlen(str);
	GByteArray *ba = g_byte_array_sized_new(len);

	g_byte_array_append(ba, (const unsigned char *)str, len);

	return ba;
}

static int setup_connection(NMConnection *con, const char *user, const char *pass) {
	NMSetting *setting;

	/* NMSettingConnection */
	setting = nm_setting_connection_new();
	g_object_set(G_OBJECT(setting),
		     NM_SETTING_CONNECTION_UUID, CONNECTION_UUID,
		     NM_SETTING_CONNECTION_ID, CONNECTION_ID,
		     NM_SETTING_CONNECTION_TYPE, NM_SETTING_WIRELESS_SETTING_NAME,
		     NULL);
	nm_connection_add_setting(con, setting);

	/* NMSettingWireless */
	setting = nm_setting_wireless_new();
	GByteArray *ssid = string_to_byte_array(CONNECTION_SSID);
	g_object_set(G_OBJECT(setting),
		     NM_SETTING_WIRELESS_SSID, ssid,
		     NM_SETTING_WIRELESS_MODE, NM_SETTING_WIRELESS_MODE_INFRA,
		     NULL);
	g_byte_array_unref(ssid);
	nm_connection_add_setting(con, setting);

	/* NMSettingWirelessSecurity */
	setting = nm_setting_wireless_security_new();
	g_object_set(G_OBJECT(setting),
		     NM_SETTING_WIRELESS_SECURITY_AUTH_ALG, CONNECTION_AUTH_ALG,
		     NM_SETTING_WIRELESS_SECURITY_KEY_MGMT, CONNECTION_KEY_MGMT,
		     NULL);
	nm_connection_add_setting(con, setting);

	/* NMSetting8021x */
	setting = nm_setting_802_1x_new();
	/* TODO: Add certificate and subject check */
	nm_setting_802_1x_add_eap_method(NM_SETTING_802_1X(setting), CONNECTION_EAP);
	g_object_set(setting,
		     NM_SETTING_802_1X_IDENTITY, user,
		     NM_SETTING_802_1X_PASSWORD, pass,
		     NM_SETTING_802_1X_PHASE2_AUTHEAP, CONNECTION_PHASE2_AUTHEAP,
		     NULL);
	nm_connection_add_setting(con, setting);

	/* NMSettingIP4Config */
	setting = nm_setting_ip4_config_new();
	g_object_set(G_OBJECT(setting),
		     NM_SETTING_IP4_CONFIG_METHOD, "auto",
		     NULL);
	nm_connection_add_setting(con, setting);

	/* NMSettingIP6Config */
	setting = nm_setting_ip6_config_new();
	g_object_set(G_OBJECT(setting),
		     NM_SETTING_IP6_CONFIG_METHOD, "auto",
		     NULL);
	nm_connection_add_setting(con, setting);

	return PAM_SUCCESS;
}

typedef struct {
	int ret;
	GMainLoop *loop;
	NMClient *client;
} cb_arg;


static NMDevice * find_device(NMClient *client) {
	size_t i;
	const GPtrArray *devices = nm_client_get_devices(client);

	for (i = 0; i < devices->len; i++) {
		NMDevice *device = g_ptr_array_index(devices, i);

		if (nm_device_get_device_type(device) == NM_DEVICE_TYPE_WIFI)
			return device;
	}

	return NULL;
}

static void state_cb(NMDevice *device, GParamSpec *pspec, gpointer user_data) {
	cb_arg *arg = user_data;

	NMActiveConnection *active_connection = nm_device_get_active_connection(device);
	if (!active_connection)
		return;

	NMActiveConnectionState state = nm_active_connection_get_state(active_connection);

	if (state != NM_ACTIVE_CONNECTION_STATE_ACTIVATING && state != NM_ACTIVE_CONNECTION_STATE_DEACTIVATING) {
		if (state == NM_ACTIVE_CONNECTION_STATE_ACTIVATED)
			arg->ret = PAM_SUCCESS;

		g_main_loop_quit(arg->loop);
	}
}

static void activate_cb(NMClient *client, NMActiveConnection *active_connection, GError *error, gpointer user_data) {
	cb_arg *arg = user_data;

	if (error)
		goto error;


	return;

 error:
	g_main_loop_quit(arg->loop);
}

static void add_cb(NMRemoteSettings *settings, NMRemoteConnection *con, GError *error, gpointer user_data) {
	cb_arg *arg = user_data;

	if (error)
		goto error;

	NMDevice *device = find_device(arg->client);
	if (!device)
		goto error;

	g_signal_connect(device, "notify::state", G_CALLBACK(state_cb), arg);
	nm_client_activate_connection(arg->client, NM_CONNECTION(con), device, NULL, activate_cb, arg);
	return;

 error:
	g_main_loop_quit(arg->loop);
}

static int do_authenticate(const char *user, const char *pass) {
	DBusGConnection *dbus = NULL;
	NMRemoteSettings *settings = NULL;
	NMConnection *con = NULL;
	cb_arg arg = {};

	arg.ret = PAM_SYSTEM_ERR;
	arg.loop = g_main_loop_new(NULL, FALSE);

	arg.client = nm_client_new();
	if (!arg.client)
		goto end;

	dbus = dbus_g_bus_get(DBUS_BUS_SYSTEM, NULL);
	if (!dbus)
		goto end;

	settings = nm_remote_settings_new(dbus);
	if (!settings)
		goto end;

	con = nm_connection_new();
	setup_connection(con, user, pass);

	if (!nm_remote_settings_add_connection_unsaved(settings, con, add_cb, &arg))
		goto end;

	arg.ret = PAM_AUTH_ERR;

	g_main_loop_run(arg.loop);

 end:
	g_object_unref(con);

	g_object_unref(settings);
	dbus_g_connection_unref(dbus);
	g_object_unref(arg.client);
	g_main_loop_unref(arg.loop);

	return arg.ret;
}

static int authenticate(const char *user, const char *pass) {
	int status;
	int fds[2];
	if (pipe(fds))
		return PAM_SYSTEM_ERR;

	pid_t pid = fork();
	if (pid < 0)
		return PAM_SYSTEM_ERR;

	if (pid == 0) {
		close(fds[0]);
		status = do_authenticate(user, pass);
		write(fds[1], &status, sizeof(status));
		close(fds[1]);
		_exit(0);
	}

	close(fds[1]);

	if (waitpid(pid, NULL, 0) < 0)
		goto error;

	if (read(fds[0], &status, sizeof(status)) != sizeof(status))
		goto error;

	close(fds[0]);
	return status;

 error:
	close(fds[0]);
	return PAM_SYSTEM_ERR;
}

#ifdef TEST

int main(int argc, char *argv[]) {
	if (argc != 2) {
		fprintf(stderr, "Usage: pam_wlan_test <user>\n");
		return 1;
	}

	char *pass = getpass("Password: ");

	fprintf(stderr, "Return: %i\n", authenticate(argv[1], pass));

	return 0;
}

#else

PAM_EXTERN int pam_sm_authenticate(pam_handle_t *pamh, __attribute__((unused)) int flags, __attribute__((unused)) int argc, __attribute__((unused)) const char **argv) {
	const void *pass;
	const void *user;
	int result;

	result = pam_get_item(pamh, PAM_USER, &user);
	if (result != PAM_SUCCESS)
		return PAM_INCOMPLETE;

	result = pam_get_item(pamh, PAM_AUTHTOK, &pass);
	if (result != PAM_SUCCESS)
		return PAM_INCOMPLETE;

	return authenticate(user, pass);
}
#endif