/*
 * dhcp_client.c
 * This file is part of Network Inador
 *
 * Copyright (C) 2021 - Félix Arreola Rodríguez
 *
 * Network Inador is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Network Inador 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Network Inador; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, 
 * Boston, MA  02110-1301  USA
 */

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

#include <time.h>

#include <fcntl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>

#include <signal.h>

#include "interfaces.h"
#include "common.h"
#include "manager.h"

#include "dhcp_client.h"
#include "network-inador-manager.h"

static void interfaces_dhcp_clear_info (InterfaceDHCPClientInfo *dhcpc);

void interfaces_dhcp_client_ignore_kill (GPid pid, gint status, gpointer data) {
	g_spawn_check_exit_status (status, NULL);
}

void interfaces_dhcp_prepare_args_for_isc_dhclient (char **argv, int size, char *iface_name, char *pid_file, size_t pid_file_len) {
	snprintf (pid_file, pid_file_len, "/run/dhclient-%s.pid", iface_name);
	
	/* Preparar los argumentos para el proceso */
	argv[0] = "/sbin/dhclient";
	argv[1] = "-d";
	argv[2] = "-q";
	argv[3] = "-pf";
	argv[4] = pid_file;
	argv[5] = "-sf";
	argv[6] = "/home/gatuno/Proyectos/NetworkInador/src/ni-dhcp-helper";
	argv[7] = iface_name;
	argv[8] = NULL;
}

void interfaces_dhcp_prepare_args_for_busybox_udhcpc (char **argv, int size, char *iface_name, char *pid_file, size_t pid_file_len) {
	snprintf (pid_file, pid_file_len, "/run/dhclient-%s.pid", iface_name);
	
	/* Preparar los argumentos para el proceso */
	argv[0] = "/bin/busybox";
	argv[1] = "udhcpc";
	argv[2] = "-i";
	argv[3] = iface_name;
	argv[4] = "-p";
	argv[5] = pid_file;
	argv[6] = "-s";
	argv[7] = "/home/gatuno/Proyectos/NetworkInador/src/ni-dhcp-helper";
	argv[8] = "-f";
	argv[9] = NULL;
}

void interfaces_dhcp_client_killed_cb (GPid pid, gint status, gpointer data) {
	Interface *iface = (Interface *) data;
	gboolean ret;
	GError *error = NULL;
	char *argv[20];
	gchar pid_file[256];
	
	/* Preparar los argumentos */
	if (iface->dhcpc.type == IFACE_ISC_DHCLIENT) {
		interfaces_dhcp_prepare_args_for_isc_dhclient (argv, 20, iface->name, pid_file, sizeof (pid_file));
	} else if (iface->dhcpc.type == IFACE_BUSYBOX_UDHCPC) {
		interfaces_dhcp_prepare_args_for_busybox_udhcpc (argv, 20, iface->name, pid_file, sizeof (pid_file));
	}
	
	if (g_spawn_check_exit_status (status, NULL)) {
		/* Revisar si necesito algo */
	}
	
	interfaces_dhcp_clear_info (&iface->dhcpc);
	/* Enviar actualización de estado aquí */
	iface->dhcpc.dhcp_state = DHCP_CLIENT_KILLED;
	manager_send_event_dhcp_change (iface->handle, &iface->dhcpc);
	
	if (iface->dhcpc.type == IFACE_ISC_DHCLIENT || iface->dhcpc.type == IFACE_BUSYBOX_UDHCPC) {
		if (iface->dhcpc.flags & DHCP_CLIENT_FLAG_AUTO_RESTART) {
			/* Se cerró o mataron el proceso, reiniciar */
			ret = g_spawn_async_with_pipes (
				"/",
				argv,
				NULL,
				G_SPAWN_DO_NOT_REAP_CHILD,
				NULL,
				NULL, 
				&iface->dhcpc.process_pid,
				NULL,
				NULL,
				NULL,
				&error);

			if (ret == FALSE) {
				printf ("Error dhcp: %s\n", error->message);
				g_error_free (error);
				error = NULL;
				
				iface->dhcpc.dhcp_state = DHCP_CLIENT_KILLED;
				iface->dhcpc.process_watch = 0;
			} else {
				iface->dhcpc.dhcp_state = DHCP_CLIENT_SELECTING;
				iface->dhcpc.process_watch = g_child_watch_add (iface->dhcpc.process_pid, interfaces_dhcp_client_killed_cb, iface);
			}
		} else {
			/* En caso contrario, solo dejar la muerte escrita */
			iface->dhcpc.dhcp_state = DHCP_CLIENT_KILLED;
			iface->dhcpc.process_watch = 0;
		}
	}
}

static void interfaces_dhcp_clear_info (InterfaceDHCPClientInfo *dhcpc) {
	memset (&dhcpc->ip, 0, sizeof (dhcpc->ip));
	dhcpc->gw_c = 0;
	dhcpc->dns_c = 0;
	memset (&dhcpc->broadcast, 0, sizeof (dhcpc->broadcast));
	memset (&dhcpc->dhcp_server_ip, 0, sizeof (dhcpc->dhcp_server_ip));
	dhcpc->lease_time = 0;
	dhcpc->prefix = 0;
	
	dhcpc->domain_name[0] = 0;
}

int interfaces_dhcp_client_run (NetworkInadorHandle *handle, int index, int type, uint32_t flags) {
	/* IFNAMSIZ */
	Interface *iface;
	gboolean ret;
	GError *error = NULL;
	char *argv[20];
	gchar pid_file[256];
	
	iface = _interfaces_locate_by_index (handle->interfaces, index);
	
	if (iface == NULL) {
		printf ("Error, solicitaron operación sobre interfaz que no existe\n");
		
		return -1;
	}
	
	/* Preparar los argumentos */
	if (type == IFACE_ISC_DHCLIENT) {
		interfaces_dhcp_prepare_args_for_isc_dhclient (argv, 20, iface->name, pid_file, sizeof (pid_file));
	} else if (type == IFACE_BUSYBOX_UDHCPC) {
		interfaces_dhcp_prepare_args_for_busybox_udhcpc (argv, 20, iface->name, pid_file, sizeof (pid_file));
	}
	if (iface->dhcpc.type != IFACE_NO_DHCP) {
		/* No puedo correr otro tipo de DHCP */
		return -1;
	}
	
	if ((iface->dhcpc.type == IFACE_ISC_DHCLIENT || iface->dhcpc.type == IFACE_BUSYBOX_UDHCPC) && iface->dhcpc.dhcp_state != DHCP_CLIENT_KILLED) {
		/* El cliente de dhcp ya está corriendo, no hacer nada */
		return -1;
	}
	
	interfaces_dhcp_clear_info (&iface->dhcpc);
	
	ret = g_spawn_async_with_pipes (
		"/",
		argv,
		NULL,
		G_SPAWN_DO_NOT_REAP_CHILD,
		NULL,
		NULL, 
		&iface->dhcpc.process_pid,
		NULL,
		NULL,
		NULL,
		&error);
	
	if (ret == FALSE) {
		
		printf ("Error dhcp: %s\n", error->message);
		g_error_free (error);
		error = NULL;
		
		return -1;
	}
	
	iface->dhcpc.dhcp_state = DHCP_CLIENT_SELECTING;
	iface->dhcpc.type = type;
	iface->dhcpc.flags = flags;
	
	iface->dhcpc.process_watch = g_child_watch_add (iface->dhcpc.process_pid, interfaces_dhcp_client_killed_cb, iface);
	
	manager_send_event_dhcp_change (handle, &iface->dhcpc);
	
	return 0;
}

int interfaces_dhcp_client_stop (NetworkInadorHandle *handle, int index) {
	Interface *iface;
	
	iface = _interfaces_locate_by_index (handle->interfaces, index);
	
	if (iface == NULL) {
		printf ("Error, solicitaron operación sobre interfaz que no existe\n");
		
		return -1;
	}
	
	if (iface->dhcpc.type == IFACE_NO_DHCP) {
		return -1;
	}
	
	if (iface->dhcpc.type == IFACE_ISC_DHCLIENT || iface->dhcpc.type == IFACE_BUSYBOX_UDHCPC) {
		if (iface->dhcpc.dhcp_state == DHCP_CLIENT_KILLED) return -1;
		
		/* Proceso, matar y reiniciar estado */
		
		iface->dhcpc.flags &= (~DHCP_CLIENT_FLAG_AUTO_RESTART);
		
		g_source_remove (iface->dhcpc.process_watch);
		iface->dhcpc.process_watch = 0;
		g_child_watch_add (iface->dhcpc.process_pid, interfaces_dhcp_client_ignore_kill, NULL);
		
		kill (iface->dhcpc.process_pid, SIGTERM);
		iface->dhcpc.type = IFACE_NO_DHCP;
		iface->dhcpc.dhcp_state = DHCP_CLIENT_KILLED;
		/* TODO: Revisar aquí si es pertinente desconfigurar la interfaz y borrar la información obtenida */
		
		interfaces_dhcp_clear_info (&iface->dhcpc);
		/* Enviar actualización de estado aquí */
		manager_send_event_dhcp_change (handle, &iface->dhcpc);
	}
	
	return 0;
}

void interfaces_dhcp_client_internal_feed_from_client (NetworkInadorHandle *handle, int index, int status, struct_addr *ip, int prefix, struct_addr *gateways, int gw_c, struct_addr *broadcast, struct_addr *dhcp_server, uint32_t lease_time, struct_addr *dns_list, int dns_count, char *domain_name) {
	Interface *iface;
	struct in_addr empty_v4;
	int g;
	struct_addr old_dns[7];
	int old_dns_c;
	
	iface = _interfaces_locate_by_index (handle->interfaces, index);
	
	if (iface == NULL) {
		printf ("Error, solicitaron operación sobre interfaz que no existe\n");
		
		return;
	}
	
	if (iface->dhcpc.type == IFACE_NO_DHCP) {
		return;
	}
	
	// TODO: Cuando entre a estado Selecting, previo otro estado diferente, borrar la IP, si es que tenemos
	if (iface->dhcpc.type == IFACE_ISC_DHCLIENT || iface->dhcpc.type == IFACE_BUSYBOX_UDHCPC) {
		/* Un proceso muerto no puede informar de cambios de estados */
		if (iface->dhcpc.dhcp_state == DHCP_CLIENT_KILLED) return;
		
		switch (status) {
			case NET_INADOR_DHCP_STATUS_SELECTING:
				iface->dhcpc.dhcp_state = DHCP_CLIENT_SELECTING;
				break;
			case NET_INADOR_DHCP_STATUS_BOUND:
				iface->dhcpc.dhcp_state = DHCP_CLIENT_BOUND;
				break;
			case NET_INADOR_DHCP_STATUS_RENEWED:
				iface->dhcpc.dhcp_state = DHCP_CLIENT_RENEWED;
				break;
			case NET_INADOR_DHCP_STATUS_EXPIRED:
				iface->dhcpc.dhcp_state = DHCP_CLIENT_EXPIRED;
				/* Borrar la IP anterior, si es que está puesta */
				break;
			case NET_INADOR_DHCP_STATUS_FAILED:
				iface->dhcpc.dhcp_state = DHCP_CLIENT_FAILED;
				break;
		}
	}
	
	printf ("----> DHCP status: %i\n", iface->dhcpc.dhcp_state);
	
	if (status == NET_INADOR_DHCP_STATUS_BOUND || status == NET_INADOR_DHCP_STATUS_RENEWED) {
		/* Copiar la información de DNS para saber si hubo cambios */
		old_dns_c = iface->dhcpc.dns_c;
		if (old_dns_c != dns_count) {
			/* Copiamos los dns viejos solo si la cantidad es diferente */
			memcpy (old_dns, iface->dhcpc.dns, old_dns_c * (sizeof (iface->dhcpc.dns[0])));
		}
		
		/* Copiar las variables de estado */
		memset (&empty_v4, 0, sizeof (empty_v4));
		
		memcpy (&iface->dhcpc.ip, ip, sizeof (iface->dhcpc.ip));
		iface->dhcpc.prefix = prefix;
		
		iface->dhcpc.gw_c = gw_c;
		for (g = 0; g < gw_c && g < 7; g++) {
			memcpy (&iface->dhcpc.gateways[g], &gateways[g], 4);
		}
		
		memcpy (&iface->dhcpc.broadcast, broadcast, sizeof (iface->dhcpc.broadcast));
		memcpy (&iface->dhcpc.dhcp_server_ip, dhcp_server, sizeof (iface->dhcpc.dhcp_server_ip));
		iface->dhcpc.lease_time = lease_time;
		
		iface->dhcpc.dns_c = dns_count;
		for (g = 0; g < dns_count && g < 7; g++) {
			memcpy (&iface->dhcpc.dns[g], &dns_list[g], 4);
		}
		
		if (iface->dhcpc.dns_c != old_dns_c) {
			/* TODO: Tenemos cambio en los DNS, actualizar el resolv.conf */
		} else if (memcmp (iface->dhcpc.dns, old_dns, dns_count * (sizeof (iface->dhcpc.dns[0]))) != 0) {
			/* TODO: Tenemos cambio en los DNS, actualizar el resolv.conf */
		}
		
		strncpy (iface->dhcpc.domain_name, domain_name, sizeof (iface->dhcpc.domain_name));
		
		/* Esto solo es para impresión */
		char buf_a[256], buf_b[256], buf_c[256], buf_d[256];
		
		inet_ntop (AF_INET, &iface->dhcpc.ip, buf_a, sizeof (buf_a));
		inet_ntop (AF_INET, &iface->dhcpc.broadcast, buf_c, sizeof (buf_c));
		inet_ntop (AF_INET, &iface->dhcpc.dhcp_server_ip, buf_d, sizeof (buf_d));
		printf ("----> (%i) DHCP Server (%s), IP obtenida: %s/%i, GW: ", (unsigned int) time (NULL), buf_d, buf_a, prefix);
		
		for (g = 0; g < gw_c; g++) {
			inet_ntop (AF_INET, &iface->dhcpc.gateways[g], buf_b, sizeof (buf_b));
			printf ("%s, ", buf_b);
		}
		printf ("bcast: %s, lease: %i, DNS: ", buf_c, lease_time);
		for (g = 0; g < dns_count; g++) {
			inet_ntop (AF_INET, &iface->dhcpc.dns[g], buf_b, sizeof (buf_b));
			printf ("%s, ", buf_b);
		}
		
		printf (" y domain name <%s>\n", domain_name);
	}
	
	manager_send_event_dhcp_change (handle, &iface->dhcpc);
}