/*
  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.
*/


/*
  See:

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

#include <stdio.h>
#include <string.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>

#include <config.h>


#define UNUSED __attribute__((unused))


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, "link-local",
		     NULL);
	nm_connection_add_setting(con, setting);

	return PAM_SUCCESS;
}

typedef struct {
	int ret;
	GMainLoop *loop;
	NMClient *client;
	NMRemoteConnection *con;
} 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 gboolean timeout_cb(gpointer user_data) {
	cb_arg *arg = user_data;
	g_main_loop_quit(arg->loop);

	return FALSE;
}

static void state_cb(NMDevice *device, UNUSED 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(UNUSED NMClient *client, UNUSED 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(UNUSED 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;

	arg->con = con;

	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);

	g_timeout_add_seconds(CONNECTION_TIMEOUT, timeout_cb, arg);
	return;

 error:
	g_main_loop_quit(arg->loop);
}

static void delete_cb(UNUSED NMRemoteConnection *connection, UNUSED GError *error, gpointer user_data) {
	cb_arg *arg = user_data;
	g_main_loop_quit(arg->loop);
}

static void read_cb(UNUSED NMRemoteSettings *settings, gpointer user_data) {
	cb_arg *arg = user_data;
	g_main_loop_quit(arg->loop);
}

static gboolean match_connection_user(NMConnection *connection, const char *user) {
	NMSetting8021x *setting = nm_connection_get_setting_802_1x(connection);
	if (!setting)
		return FALSE;

	const char *identity = nm_setting_802_1x_get_identity(setting);
	if (!identity)
		return FALSE;

	return (strcmp(identity, user) == 0);
}

static gboolean is_connection_active(NMConnection *connection, cb_arg *arg) {
	NMDevice *device = find_device(arg->client);
	if (!device)
		return FALSE;

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

	if (strcmp(nm_connection_get_path(connection), nm_active_connection_get_connection(active_connection)) != 0)
		return FALSE;

	NMActiveConnectionState state = nm_active_connection_get_state(active_connection);

	return (state == NM_ACTIVE_CONNECTION_STATE_ACTIVATED);
}

static gboolean handle_old_connection(NMRemoteSettings *settings, const char *user, cb_arg *arg) {
	NMRemoteConnection *con = NULL;

	g_signal_connect(settings, NM_REMOTE_SETTINGS_CONNECTIONS_READ,
			 G_CALLBACK(read_cb), arg);

	g_main_loop_run(arg->loop);

	con = nm_remote_settings_get_connection_by_uuid(settings, CONNECTION_UUID);
	if (!con)
		goto end;

	if (match_connection_user(NM_CONNECTION(con), user) && is_connection_active(NM_CONNECTION(con), arg))
		return TRUE;

	nm_remote_connection_delete(con, delete_cb, arg);
	g_main_loop_run(arg->loop);

 end:
	return FALSE;
}

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

	arg.ret = PAM_SERVICE_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;

	if (handle_old_connection(settings, user, &arg)) {
		arg.ret = PAM_IGNORE;
		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);

	if (arg.ret == PAM_SUCCESS)
		goto end;

	/* Error */
	if (arg.con) {
		nm_remote_connection_delete(arg.con, delete_cb, &arg);
		g_main_loop_run(arg.loop);
	}

 end:
	if (con)
		g_object_unref(con);
	if (settings)
		g_object_unref(settings);
	if (dbus)
		dbus_g_connection_unref(dbus);
	if (arg.client)
		g_object_unref(arg.client);
	g_main_loop_unref(arg.loop);

	return arg.ret;
}

int main() {
	char buf[1024];
	size_t len = 0;

	while (len < sizeof(buf)-1) {
		size_t r = fread(buf+len, 1, sizeof(buf)-len-1, stdin);
		if (!r)
			break;

		len += r;
	}

	buf[len] = 0;

	const char *user = buf;
	const char *pass = user + strlen(user) + 1;
	if (pass > buf+len)
		return PAM_SYSTEM_ERR;

	return authenticate(user, pass);
}