/* $Id$
 * UDP Gateway utility network layer
 * Copyright (C) 2004 Jan Kratochvil <project-udpgate@jankratochvil.net>
 * 
 * This program 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; exactly version 2 of June 1991 is required
 * 
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */


#include "config.h"

#include <glib/gmessages.h>
#include <glib/gmain.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <glib/glist.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <signal.h>
#include <errno.h>
#include <glib/giochannel.h>
#include <sys/ioctl.h>
#include <string.h>
#include <glib/galloca.h>
#include <glib/gprintf.h>
#include <glib/grand.h>
#include <glib/gutils.h>

#include "network.h"
#include "packet.h"
#include "main.h"	/* for optarg_verbose */
#include "pathname.h"


/* Config: */
#define SOCK_SOURCE_CHECK_REVENTS (G_IO_IN|G_IO_OUT)	/* |G_IO_ERR|G_IO_HUP|G_IO_NVAL */
#define SERVER_INADDR 0xC37AD054	/* mms2.org = 195.122.208.84; host order */
#define SERVER_PORT   9201	/* host order */
#define PROBE_INADDR  SERVER_INADDR	/* host order */
#define PROBE_PORT    8201	/* host order */
#define CLIENT_TIMEOUT_SEC (5*60)
#define PROBE_TIMEOUT_SEC_BASE 5
#define PROBE_TIMEOUT_SEC_MAX 3500
#define TCP_BACKLOG 5
#define GSTRING_TO_SEND_MAX 1500*6	/* maximum data buffered per TCP client */


void (*network_notify_hostip)(guint32 hostip_guint32);


static G_CONST_RETURN gchar *pid_pathname(void)
{
static const gchar *static_pathname;
static const char *user_val;

	if (!static_pathname)
		user_val=g_get_user_name();
	return pathname_find(&static_pathname,
			G_STRINGIFY(LOCALSTATEDIR) "/run",PACKAGE ".pid",
			(!user_val ? NULL : g_get_tmp_dir()),
					(!user_val ? NULL : udpgate_printf_alloca(".%s-%s.pid",user_val,PACKAGE)),
			NULL);
}


struct client {
	GPollFD gpollfd;
	struct sockaddr_in sockaddr_in_from;
	guint timeout_id;
	struct client *bound;
	unsigned connect_pending:1;	/* for TCP connection to the server; activated by: G_IO_OUT */
	unsigned server_only:1;	/* nonimportant connect - the server side */
	unsigned done:1;	/* temporary marker */
	GString *gstring_to_send;	/* for TCP connections; data to be sent to this socket */
	};

static GSource *sock_gsource;

static GList *sock_client_list;	/* of 'struct client *', incl. 'master' and 'probe' */
static struct client *master_udp;	/* no 'timeout' permitted */
static struct client *master_tcp;	/* no 'timeout' permitted */
static struct client *probe;	/* 'timeout' permitted */
static guint32 probe_unique;
static guint probe_timeout_sec_now;
guint probe_timeout_sec_max=G_MAXUINT;
static gint port_local;	/* for 'probe' resends */

static gboolean write_daemon_running(pid_t pid);

pid_t is_daemon_running(void)
{
FILE *f;
char buf[LINE_MAX],*got;
int pid_int;

	if (sock_gsource)
		return getpid();

	if (!(f=fopen(pid_pathname(),"r")))
		goto err;
	got=fgets(buf,sizeof(buf),f);
	fclose(f);	/* FIXME: error ignored */
	if (got!=buf) {
err_unlink:
		write_daemon_running((pid_t)-1);	/* unlink */
err:
		return (pid_t)-1;
		}
	pid_int=atoi(buf);
	if (pid_int<=1)
		goto err_unlink;
	if (kill((pid_t)pid_int,0)) {
		if (errno==ESRCH)
			goto err_unlink;
		goto err;
		}
	return (pid_t)pid_int;
}

static gboolean write_daemon_running(pid_t pid)
{
FILE *f;

	if (pid==(pid_t)-1) {
		if (unlink(pid_pathname())) {
			if (errno!=ENOENT)
				g_warning(_("Error removing PID file \"%s\": %m"),pid_pathname());
			return FALSE;
			}
		return TRUE;
		}
	if (!(f=fopen(pid_pathname(),"w"))) {
static gboolean once=TRUE;

		if (once) {
			once=FALSE;
			g_warning(_("Error writing PID %d to \"%s\": %m"),(int)pid,pid_pathname());
			}
		return FALSE;
		}
	fprintf(f,"%d\n",(int)pid);	/* errors ignored */
	fclose(f);	/* FIXME: error ignored */
	return TRUE;
}

static void client_timeout_remove(struct client *client)
{
	g_return_if_fail(client!=NULL);
	g_return_if_fail(client!=master_udp);
	g_return_if_fail(client!=master_tcp);

	if (client->timeout_id) {
gboolean errgboolean;

		if (optarg_verbose)
			g_message(_("Client fd %d removed timeout id %d"),client->gpollfd.fd,client->timeout_id);
		errgboolean=g_source_remove(client->timeout_id);
		g_assert(errgboolean==TRUE);
		client->timeout_id=0;
		}
}

static gboolean client_touch_timeout(struct client *client);

static void client_touch(struct client *client,guint timeout_sec)
{
	g_return_if_fail(client!=NULL);
	g_return_if_fail(client!=master_udp);
	g_return_if_fail(client!=master_tcp);
	g_return_if_fail(timeout_sec>0);

	client_timeout_remove(client);
	client->timeout_id=g_timeout_add(
			timeout_sec*1000,	/* interval; msec */
			(GSourceFunc)client_touch_timeout,	/* function */
			client);	/* data */
	if (optarg_verbose)
		g_message(_("Client fd %d new timeout id %d"),client->gpollfd.fd,client->timeout_id);
	g_assert(client->timeout_id!=0);
}

static void client_destroy(struct client *client);
static gboolean probe_send(struct client *probe,gint port_local);

static gboolean client_touch_timeout(struct client *client)
{
	g_return_val_if_fail(client!=NULL,FALSE);	/* FALSE=>should be removed */
	g_return_val_if_fail(client!=master_udp,FALSE);	/* FALSE=>should be removed */
	g_return_val_if_fail(client!=master_tcp,FALSE);	/* FALSE=>should be removed */

	if (optarg_verbose)
		g_message(_("Client fd %d timeout id %d occured/entered"),client->gpollfd.fd,client->timeout_id);

	/* Do not destroy the timeout in client_destroy().
	 * It would crash GLib - we remove it be returning FALSE from here.
	 */
	g_assert(client->timeout_id!=0);
	client->timeout_id=0;

	if (client==probe) {
		if (probe_timeout_sec_now<probe_timeout_sec_max) {
			probe_timeout_sec_now*=PROBE_TIMEOUT_SEC_BASE;
			g_assert(probe_timeout_sec_max==G_MAXUINT || probe_timeout_sec_max<PROBE_TIMEOUT_SEC_MAX);
			probe_timeout_sec_now=MIN(probe_timeout_sec_now,probe_timeout_sec_max);
			probe_timeout_sec_now=MIN(probe_timeout_sec_now,PROBE_TIMEOUT_SEC_MAX);
			if (probe_send(probe,port_local)) {
				client_touch(probe,probe_timeout_sec_now);	/* timeout */
				return FALSE;	/* GSource should be removed */
				}
			/* failure FALLTHRU */
			}
		network_stop();
		/* Never destroy 'client' now - it has been destroyed by network_stop()! */
		g_warning(_("No probe response from the server, stopping the daemon. Please check your public Internet connectivity."));
		}
	else {
		client_destroy(client);
		}

	if (optarg_verbose)
		g_message(_("Client timeout occurance finish"));

	return FALSE;	/* GSource should be removed */
}

static void handle_master_probe(const void *packet,size_t gotlen,const struct sockaddr_in *sockaddr_in_from)
{
GHashTable *got_hash;
gpointer got_unique_gpointer;
gpointer hostip_gpointer;
guint32 hostip_guint32;

	g_return_if_fail(packet!=NULL);
	g_return_if_fail(sockaddr_in_from!=NULL);

	if (!probe)
		return;

	if (!(got_hash=packet_disassembly(packet,gotlen)))
		return;
	if (!(g_hash_table_lookup_extended(
			got_hash,	/* hash_table */
			GUINT_TO_POINTER(PACKET_ELEM_TYPE_DATA_GUINT32),	/* lookup_key */
			NULL,	/* orig_key */
			&got_unique_gpointer))) {
err_packet_disassembly_destroy_got_hash:
		packet_disassembly_destroy(got_hash);
		return;
		}
	if (GPOINTER_TO_UINT(got_unique_gpointer)!=probe_unique)
		goto err_packet_disassembly_destroy_got_hash;
	if (!(g_hash_table_lookup_extended(
			got_hash,	/* hash_table */
			GUINT_TO_POINTER(PACKET_ELEM_TYPE_CLIENT_INADDR),	/* lookup_key */
			NULL,	/* orig_key */
			&hostip_gpointer)))
		goto err_packet_disassembly_destroy_got_hash;
	hostip_guint32=GPOINTER_TO_UINT(hostip_gpointer);
	packet_disassembly_destroy(got_hash);

	client_destroy(probe);
	if (network_notify_hostip)
		(*network_notify_hostip)(hostip_guint32);
}

enum client_new_type {
	CLIENT_NEW_TYPE_UDP,
	CLIENT_NEW_TYPE_TCP,
	};

static struct client *client_new(enum client_new_type type);
static struct client *client_new_from_sock(int sock);

static void clients_bind(struct client *client0,struct client *client1)
{
	g_return_if_fail(client0!=NULL);
	g_return_if_fail(client0->bound==NULL);
	g_return_if_fail(client0->gstring_to_send==NULL);
	g_return_if_fail(client1!=NULL);
	g_return_if_fail(client1->bound==NULL);
	g_return_if_fail(client1->gstring_to_send==NULL);
	g_return_if_fail(client0!=client1);

	client0->bound=client1;
	client1->bound=client0;

	client0->gstring_to_send=g_string_sized_new(GSTRING_TO_SEND_MAX);
	client1->gstring_to_send=g_string_sized_new(GSTRING_TO_SEND_MAX);
}

static void client_split(struct client *client)
{
	g_return_if_fail(client!=NULL);
	g_return_if_fail(client->bound!=NULL);
	g_return_if_fail(client->bound!=client);
	g_return_if_fail(client->bound->bound==client);
	g_return_if_fail(client->gstring_to_send!=NULL);

	client->bound->bound=NULL;
	client->bound=NULL;
}

static struct sockaddr_in sockaddr_in_server;

static void handle_master_udp(struct client *master_udp)
{
	g_return_if_fail(master_udp!=NULL);

	for (;;) {
char packet[0x10000];
ssize_t gotlen;
struct sockaddr_in sockaddr_in_from;
struct client *client=NULL	/* Prevent false positive: might be used uninitialized */;
socklen_t sockaddr_in_from_length;
GList *clientl;

		sockaddr_in_from_length=sizeof(sockaddr_in_from);
		if (-1==(gotlen=recvfrom(
				master_udp->gpollfd.fd,	/* s */
				packet,	/* buf */
				sizeof(packet),	/* len */
				0,	/* flags */
				(struct sockaddr *)&sockaddr_in_from,	/* from */
				&sockaddr_in_from_length)))	/* fromlen */
			break;

		if (sockaddr_in_from_length!=sizeof(sockaddr_in_from))	/* FIXME: errors reporting */
			continue;

		if (packet_recognized(packet,gotlen)) {
			handle_master_probe(packet,gotlen,&sockaddr_in_from);
			continue;
			}
		/* Not yet initialized by 'probe' reply - drop it. */
		if (probe) {
			if (optarg_verbose)
				g_message(_("Data packet received from %s but no probe reply yet; dropping packet."),
						SOCKADDR_IN_TO_STRING(&sockaddr_in_from));
			continue;
			}

		/* FIXME: Performance: Ugly search... */
		for (clientl=sock_client_list;clientl;clientl=clientl->next) {
			client=clientl->data;
			if (client==master_udp)
				continue;
			if (1
					&& client->sockaddr_in_from.sin_family     ==sockaddr_in_from.sin_family
					&& client->sockaddr_in_from.sin_port       ==sockaddr_in_from.sin_port
					&& client->sockaddr_in_from.sin_addr.s_addr==sockaddr_in_from.sin_addr.s_addr)
				break;
			}
		if (!clientl) {
			client=client_new(CLIENT_NEW_TYPE_UDP);
			client->sockaddr_in_from=sockaddr_in_from;
			}
		client_touch(client,CLIENT_TIMEOUT_SEC);
		/* FIXME: errors checking */
		sendto(
				client->gpollfd.fd,	/* s */
				packet,	/* msg */
				gotlen,	/* len */
				0,	/* flags */
				(struct sockaddr *)&sockaddr_in_server,	/* to */
				sizeof(sockaddr_in_server));	/* tolen */
		}
}

static void handle_master_tcp(struct client *master_tcp)
{
	g_return_if_fail(master_tcp!=NULL);

	for (;;) {
int sock_new;
struct sockaddr_in sockaddr_in_from;
struct client *client=NULL	/* Prevent false positive: might be used uninitialized */;
socklen_t sockaddr_in_from_length;
int connect_got;
struct client *server;

		sockaddr_in_from_length=sizeof(sockaddr_in_from);
		if (-1==(sock_new=accept(
				master_tcp->gpollfd.fd,	/* s */
				(struct sockaddr *)&sockaddr_in_from,	/* from */
				&sockaddr_in_from_length)))	/* fromlen */
			break;

		if (sockaddr_in_from_length!=sizeof(sockaddr_in_from))	/* FIXME: errors reporting */
			continue;

		/* Not yet initialized by 'probe' reply - drop it. */
		if (probe) {
			if (optarg_verbose)
				g_message(_("Incoming connection received from %s but no probe reply yet; dropping connection."),
						SOCKADDR_IN_TO_STRING(&sockaddr_in_from));
			close(sock_new);	/* FIXME: errors reporting */
			continue;
			}

		if (!(client=client_new_from_sock(sock_new)))
			continue;
		client->sockaddr_in_from=sockaddr_in_from;

		if (!(server=client_new(CLIENT_NEW_TYPE_TCP))) {
			client_destroy(client);
			continue;
			}
		server->server_only=1;
		server->sockaddr_in_from=sockaddr_in_server;
		clients_bind(client,server);
		/* Currently only one of 'client' or 'server' needs to be destroyed. */

		errno=0;
		connect_got=connect(
				server->gpollfd.fd,	/* sockfd */
				(struct sockaddr *)&sockaddr_in_server,	/* to */
				sizeof(sockaddr_in_server));	/* tolen */
		if (connect_got!=-1 || errno!=EINPROGRESS) {
			g_warning(_("Error establishing server TCP connection: %m"));
			client_destroy(server);
			continue;
			}
		g_assert(!server->connect_pending);
		server->connect_pending=1;
		}
}

static void handle_probe(struct client *probe)
{
	g_return_if_fail(probe!=NULL);

	for (;;) {
ssize_t gotlen;
struct sockaddr_in sockaddr_in_from;
char packet[0x10000];
socklen_t sockaddr_in_from_length;

		sockaddr_in_from_length=sizeof(sockaddr_in_from);
		if (-1==(gotlen=recvfrom(
				master_udp->gpollfd.fd,	/* s */
				packet,	/* buf */
				sizeof(packet),	/* len */
				0,	/* flags */
				(struct sockaddr *)&sockaddr_in_from,	/* from */
				&sockaddr_in_from_length)))	/* fromlen */
			break;
		if (sockaddr_in_from_length!=sizeof(sockaddr_in_from))	/* FIXME: errors reporting */
			continue;

		/* Probe socket should have no response; maybe some ICMP errors - ignored. */
		}
}

static void handle_client_udp(struct client *client)
{
	g_return_if_fail(client!=NULL);
	g_return_if_fail(master_udp!=NULL);

	for (;;) {
ssize_t gotlen;
struct sockaddr_in sockaddr_in_from;
char packet[0x10000];
socklen_t sockaddr_in_from_length;

		sockaddr_in_from_length=sizeof(sockaddr_in_from);
		if (-1==(gotlen=recvfrom(
				client->gpollfd.fd,	/* s */
				packet,	/* buf */
				sizeof(packet),	/* len */
				0,	/* flags */
				(struct sockaddr *)&sockaddr_in_from,	/* from */
				&sockaddr_in_from_length)))	/* fromlen */
			break;
		if (sockaddr_in_from_length!=sizeof(sockaddr_in_from))	/* FIXME: errors reporting */
			continue;
		client_touch(client,CLIENT_TIMEOUT_SEC);
		/* FIXME: errors checking */
		sendto(
				master_udp->gpollfd.fd,	/* s */
				packet,	/* msg */
				gotlen,	/* len */
				0,	/* flags */
				(struct sockaddr *)&client->sockaddr_in_from,	/* to */
				sizeof(client->sockaddr_in_from));	/* tolen */
		}
}

static void handle_client_tcp_connect(struct client *server)
{
	g_return_if_fail(server!=NULL);
	g_return_if_fail(server->connect_pending);
	g_return_if_fail(master_tcp!=NULL);

	errno=0;
	if (connect(
			server->gpollfd.fd,	/* sockfd */
			(struct sockaddr *)&sockaddr_in_server,	/* to */
			sizeof(sockaddr_in_server))) {	/* tolen */
		g_warning(_("Error establishing server TCP connection: %m"));
		client_destroy(server);
		return;
		}
	g_assert(server->connect_pending);
	server->connect_pending=0;
}

/* Read from client->gpollfd.fd the data for client->bound->gstring_to_send. */
static void handle_client_tcp_read(struct client *client)
{
	g_return_if_fail(client!=NULL);
	g_return_if_fail(client->bound!=NULL);
	g_return_if_fail(!client->connect_pending);
	g_return_if_fail(master_tcp!=NULL);

	for (;;) {
ssize_t gotlen;
size_t read_max;
char buf[GSTRING_TO_SEND_MAX];

		read_max=sizeof(buf)-client->bound->gstring_to_send->len;
		g_assert(read_max>=0);
		if (read_max<=0)	/* In fact it initially should not happen, there would be no: G_IO_IN */
			break;
		gotlen=read(client->gpollfd.fd,buf,read_max);
		if (gotlen==-1) {
			if (errno==EAGAIN)
				break;
			g_warning(_("Error reading data from %s"),SOCKADDR_IN_TO_STRING(&client->sockaddr_in_from));
			client_destroy(client);
			return;
			}
		if (gotlen==0) {
			/* Successful close; leave the bound peer's 'gstring_to_send' to be written there. */
			if (client->server_only && client->bound->gstring_to_send->len)
				client_split(client);
			client_destroy(client);
			return;
			}
		g_assert(gotlen>0);
		g_assert((size_t)gotlen<=read_max);
		g_string_append_len(client->bound->gstring_to_send,buf,gotlen);
		}
}

/* Write to client->gpollfd.fd the data from client->gstring_to_send. */
static void handle_client_tcp_write(struct client *client)
{
	g_return_if_fail(client!=NULL);
	g_return_if_fail(!client->connect_pending);
	g_return_if_fail(master_tcp!=NULL);

	for (;;) {
ssize_t gotlen;

		if (client->gstring_to_send->len<=0)	/* In fact it initially should not happen, there would be no: G_IO_OUT */
			break;
		gotlen=write(client->gpollfd.fd,client->gstring_to_send->str,client->gstring_to_send->len);
		if (gotlen==-1) {
			if (errno==EAGAIN)
				break;
			g_warning(_("Error writing data to %s"),SOCKADDR_IN_TO_STRING(&client->sockaddr_in_from));
			client_destroy(client);
			return;
			}
		if (gotlen<=0)
			break;
		g_assert((size_t)gotlen<=client->gstring_to_send->len);
		g_string_erase(client->gstring_to_send,0,gotlen);
		}

	/* Nothing left to do for such client. */
	if (!client->gstring_to_send->len && !client->bound)
		client_destroy(client);
}

static gboolean sock_source_callback(gpointer data /* unused */)
{
GList *clientl;

	/* FIXME: Quadratic 'done' marking to not to stick on stale entry! */

	for (clientl=sock_client_list;clientl;clientl=clientl->next) {
struct client *client=clientl->data;

		client->done=0;
		}
retry_in:
	for (clientl=sock_client_list;clientl;clientl=clientl->next) {
struct client *client=clientl->data;

		if (client->done)
			continue;
		client->done=1;
		if (client->gpollfd.revents&G_IO_IN) {
			/**/ if (client==master_udp)
				handle_master_udp(client);
			else if (client==master_tcp)
				handle_master_tcp(client);
			else if (client==probe)
				handle_probe(client);
			else if (client->connect_pending)
				g_assert_not_reached();
			else if (client->bound)
				handle_client_tcp_read(client);
			else
				handle_client_udp(client);
			}
		goto retry_in;
		}

	for (clientl=sock_client_list;clientl;clientl=clientl->next) {
struct client *client=clientl->data;

		client->done=0;
		}
retry_out:
	for (clientl=sock_client_list;clientl;clientl=clientl->next) {
struct client *client=clientl->data;

		if (client->done)
			continue;
		client->done=1;
		if (client->gpollfd.revents&G_IO_OUT) {
			/**/ if (client==master_udp)
				g_assert_not_reached();
			else if (client==master_tcp)
				g_assert_not_reached();
			else if (client==probe)
				g_assert_not_reached();
			else if (client->connect_pending)
				handle_client_tcp_connect(client);
			else if (client->gstring_to_send)
				handle_client_tcp_write(client);
			else
				g_assert_not_reached();
			}
		goto retry_out;
		}

	return TRUE; /* the source should be kept active */
}

static gboolean sock_source_prepare(GSource *source,gint *timeout)
{
GList *clientl;

	*timeout=-1;

	for (clientl=sock_client_list;clientl;clientl=clientl->next) {
struct client *client=clientl->data;

		client->gpollfd.events=G_IO_IN;
		if (!client->bound && client->gstring_to_send)
			client->gpollfd.events&=~G_IO_IN;
		if (client->bound && client->bound->gstring_to_send->len>=GSTRING_TO_SEND_MAX)
			client->gpollfd.events&=~G_IO_IN;
		if (client->connect_pending)
			client->gpollfd.events&=~G_IO_IN;
		if (client->bound && client->bound->connect_pending)
			client->gpollfd.events&=~G_IO_IN;
		if (client->connect_pending)
			client->gpollfd.events|=G_IO_OUT;
		if (client->gstring_to_send && client->gstring_to_send->len>0)
			client->gpollfd.events|=G_IO_OUT;
		g_assert(!(client->gpollfd.events&~SOCK_SOURCE_CHECK_REVENTS));
		}
	return FALSE;
}

static gboolean sock_source_check(GSource *source)
{
GList *clientl;

	for (clientl=sock_client_list;clientl;clientl=clientl->next) {
struct client *client=clientl->data;

		if (client->gpollfd.revents&SOCK_SOURCE_CHECK_REVENTS)
			return TRUE;
		}
	return FALSE;
}

static gboolean sock_source_dispatch(GSource *source,GSourceFunc callback,gpointer user_data)
{
	g_assert(callback!=NULL);
	return (*callback)(user_data);
}

static GSourceFuncs sock_source_watch_funcs={
		sock_source_prepare,
		sock_source_check,
		sock_source_dispatch,
		NULL, /* finalize */
		};

static void sock_gsource_destroy(void)
{
	while (sock_client_list)
		client_destroy(sock_client_list->data);

	g_assert(master_udp==NULL);
	g_assert(master_tcp==NULL);
	g_assert(probe==NULL);

	if (sock_gsource) {
		g_source_destroy(sock_gsource);
		sock_gsource=NULL;
		}

	write_daemon_running((pid_t)-1);	/* unlink; errors ignored */
}

static gboolean sock_gsource_new(void)
{
	if (sock_gsource)
		return TRUE;

	g_assert(sock_client_list==NULL);

	/* attach sock_source_callback() to watch for any abnormalities
	 * on our open pipe 'parentheart_fds' and terminate the child if parent dies.
	 */
	if (!(sock_gsource=g_source_new(&sock_source_watch_funcs,sizeof(GSource)))) {
		g_warning("g_source_new(): %m");
		return FALSE;
		}
	g_source_set_callback(
			sock_gsource,  /* source */
			sock_source_callback,  /* func */
			NULL, /* data */
			NULL);  /* notify */
	if (!g_source_attach(	/* returns 'guint' id */
			sock_gsource,  /* source */
			NULL)) {	/* context; NULL means 'default context' */
		g_warning("g_source_attach(gsource,NULL): %m");
		sock_gsource_destroy();
		return FALSE;
		}
	return TRUE;
}

static struct client *client_new_from_sock(int sock)
{
struct client *client;
static unsigned long oneul=1;

	g_return_val_if_fail(sock>=0,NULL);

	if (!sock_gsource_new())
		return FALSE;

	if (ioctl(sock,FIONBIO,&oneul)) {	/* non-blocking mode */
		g_warning("ioctl(sock,FIONBIO,&1): %m");
		close(sock);	/* errors ignored */
		return NULL;
		}

	udpgate_new(client);
	client->gpollfd.fd=sock;
	client->gpollfd.events=0;	/* Initialized later. */
	client->gpollfd.revents=0;	/* Probably does not need to be initialized. */
	client->timeout_id=0;
	client->bound=NULL;
	client->connect_pending=0;
	client->server_only=0;
	client->gstring_to_send=0;
	sock_client_list=g_list_prepend(sock_client_list,client);
	g_source_add_poll(sock_gsource,&client->gpollfd);

	if (optarg_verbose)
		g_message(_("Client fd %d created"),client->gpollfd.fd);

	return client;
}

static struct client *client_new(enum client_new_type type)
{
int sock;

	switch (type) {
		case CLIENT_NEW_TYPE_UDP:
			if (-1==(sock=socket(PF_INET,SOCK_DGRAM,IPPROTO_UDP))) {
				g_warning("socket(PF_INET,SOCK_DGRAM,IPPROTO_UDP): %m");
				return NULL;
				}
			break;
		case CLIENT_NEW_TYPE_TCP:
			if (-1==(sock=socket(PF_INET,SOCK_STREAM,IPPROTO_TCP))) {
				g_warning("socket(PF_INET,SOCK_STREAM,IPPROTO_TCP): %m");
				return NULL;
				}
			break;
		default: g_assert_not_reached();
		}

	return client_new_from_sock(sock);
}

static void client_destroy(struct client *client)
{
struct client *bound;

	g_return_if_fail(client!=NULL);

	if (!sock_gsource_new())
		return;

	if (optarg_verbose)
		g_message(_("Client fd %d timeout id %d destroy enter"),client->gpollfd.fd,client->timeout_id);

	if (client==master_udp) {
		master_udp=NULL;
		g_assert(client->timeout_id==0);
		}
	else if (client==master_tcp) {
		master_tcp=NULL;
		g_assert(client->timeout_id==0);
		}
	else {
		if (client==probe)
			probe=NULL;
		client_timeout_remove(client);
		}

	g_source_remove_poll(sock_gsource,&client->gpollfd);
	sock_client_list=g_list_remove(sock_client_list,client);
	close(client->gpollfd.fd);	/* errors ignored */

	if (client->gstring_to_send)
		g_string_free(client->gstring_to_send,TRUE);

	if (optarg_verbose)
		g_message(_("Client fd %d timeout id %d destroy finish"),client->gpollfd.fd,client->timeout_id);

	bound=client->bound;
	g_free(client);

	if (bound) {
		g_assert(bound!=client);
		g_assert(bound->bound==client);
		client->bound=NULL;
		bound->bound=NULL;
		client_destroy(bound);
		}
}

static gboolean probe_send(struct client *probe,gint port_local)
{
struct sockaddr_in sockaddr_in_probe;
GHashTable *probe_hash;
gpointer packet;
size_t packet_length;

	g_return_val_if_fail(probe!=NULL,FALSE);

	probe_unique=g_random_int();

	probe_hash=g_hash_table_new(
			g_direct_hash,	/* hash_func */
			g_direct_equal);	/* key_equal_func */
	g_hash_table_insert(probe_hash,GUINT_TO_POINTER(PACKET_ELEM_TYPE_CLIENT_PORT) ,GUINT_TO_POINTER(port_local));
	g_hash_table_insert(probe_hash,GUINT_TO_POINTER(PACKET_ELEM_TYPE_DATA_GUINT32),GUINT_TO_POINTER(probe_unique));
	packet=packet_assembly(&packet_length,probe_hash);
	g_hash_table_destroy(probe_hash);
	if (!packet)
		return FALSE;

	UDPGATE_MEMZERO(&sockaddr_in_probe);
	sockaddr_in_probe.sin_family=AF_INET;
	sockaddr_in_probe.sin_port=htons(PROBE_PORT);
	sockaddr_in_probe.sin_addr.s_addr=htonl(PROBE_INADDR);
	/* FIXME: errors checking */
	sendto(
			probe->gpollfd.fd,	/* s */
			packet,	/* msg */
			packet_length,	/* len */
			0,	/* flags */
			(struct sockaddr *)&sockaddr_in_probe,	/* to */
			sizeof(sockaddr_in_probe));	/* tolen */

	return TRUE;
}

static gboolean master_udp_start(gint port,const struct sockaddr_in *sockaddr_in_pointer)
{
	g_return_val_if_fail(master_udp==NULL,FALSE);

	if (!(master_udp=client_new(CLIENT_NEW_TYPE_UDP)))
		return FALSE;
	if (bind(master_udp->gpollfd.fd,(struct sockaddr *)sockaddr_in_pointer,sizeof(*sockaddr_in_pointer))) {
		g_warning("bind(sock_udp,{AF_INET,INADDR_ANY:%d}): %m",(int)port);
		return FALSE;
		}
	return TRUE;
}

static gboolean master_tcp_start(gint port,const struct sockaddr_in *sockaddr_in_pointer)
{
static int onei=1;

	g_return_val_if_fail(master_tcp==NULL,FALSE);

	if (!(master_tcp=client_new(CLIENT_NEW_TYPE_TCP)))
		return FALSE;
	if (setsockopt(master_tcp->gpollfd.fd,SOL_SOCKET,SO_REUSEADDR,&onei,sizeof(onei))) {
		g_warning("setsockopt(sock_tcp,SOL_SOCKET,SO_REUSEADDR,1): %m");
		return FALSE;
		}
	if (bind(master_tcp->gpollfd.fd,(struct sockaddr *)sockaddr_in_pointer,sizeof(*sockaddr_in_pointer))) {
		g_warning("bind(sock_tcp,{AF_INET,INADDR_ANY:%d}): %m",(int)port);
		return FALSE;
		}
	if (listen(master_tcp->gpollfd.fd,TCP_BACKLOG)) {
		g_warning("listen(sock_tcp,%d): %m",TCP_BACKLOG);
		return FALSE;
		}
	return TRUE;
}

static gboolean master_start(gint port)
{
struct sockaddr_in sockaddr_in;
uint16_t port_use;

	g_return_val_if_fail(port>=0,FALSE);
	g_return_val_if_fail(master_udp==NULL,FALSE);
	g_return_val_if_fail(master_tcp==NULL,FALSE);

	port_use=port;
	if (port < 0 || port_use != port) {
		g_warning(_("Port value %d is not valid for IPv4!"),(int)port);
		return FALSE;
		}
	UDPGATE_MEMZERO(&sockaddr_in);
	sockaddr_in.sin_family=AF_INET;
	sockaddr_in.sin_port=htons(port_use);
	sockaddr_in.sin_addr.s_addr=htonl(INADDR_ANY);

	if (!master_udp_start(port,&sockaddr_in))
		return FALSE;
	if (!master_tcp_start(port,&sockaddr_in)) {
		client_destroy(master_udp);
		return FALSE;
		}
	return TRUE;
}

static gboolean probe_start(gint port)
{
	g_return_val_if_fail(port>=0,FALSE);
	g_return_val_if_fail(probe==NULL,FALSE);

	/* Setup 'probe': */
	if (!(probe=client_new(CLIENT_NEW_TYPE_UDP)))
		return FALSE;
	port_local=port;
	if (!probe_send(probe,port)) {
		client_destroy(probe);
		return FALSE;
		}
	probe_timeout_sec_now=PROBE_TIMEOUT_SEC_BASE;
	client_touch(probe,probe_timeout_sec_now);	/* timeout */
	return TRUE;
}

gboolean network_start(gint port)
{
pid_t daemon_pid;

	g_return_val_if_fail(port>=0,FALSE);

	UDPGATE_MEMZERO(&sockaddr_in_server);
	sockaddr_in_server.sin_family=AF_INET;
	sockaddr_in_server.sin_port=htons(SERVER_PORT);
	sockaddr_in_server.sin_addr.s_addr=htonl(SERVER_INADDR);

	if ((pid_t)-1!=(daemon_pid=is_daemon_running())) {
		g_warning(_("Cannot start network daemon: Daemon is already running on PID %d"),(int)daemon_pid);
		return FALSE;
		}
	if (!master_start(port)) {
		sock_gsource_destroy();
		return FALSE;
		}
	if (!probe_start(port)) {
		sock_gsource_destroy();
		return FALSE;
		}
	write_daemon_running(getpid());	/* errors ignored */
	if (network_notify_hostip)
		(*network_notify_hostip)(0);
	return TRUE;
}

gboolean optarg_port_set_string(const gchar *port_string)
{
char *endp;
long port_long;

	g_return_val_if_fail(port_string!=NULL,FALSE);

	port_long=strtol(port_string,&endp,0);
	if (endp && *endp) {
		g_warning(_("Invalid port specification, offending string: %s"),endp);
		return FALSE;
		}
	if (port_long<1 || port_long>=G_MAXINT || (endp && *endp)) {
		g_warning(_("Invalid port integer number specification (%ld)"),port_long);
		return FALSE;
		}
	optarg_port=port_long;
	return TRUE;
}

gboolean network_stop(void)
{
pid_t daemon_pid;
int errno_save;

	if ((pid_t)-1==(daemon_pid=is_daemon_running())) {
		g_warning(_("Cannot stop network daemon: Daemon is not running"));
		return FALSE;
		}
	if (daemon_pid==getpid()) {
		sock_gsource_destroy();
		goto ok;
		}
	errno=0;
	kill(daemon_pid,SIGKILL);
	errno_save=errno;
	write_daemon_running((pid_t)-1);	/* unlink; errors ignored */
	if (errno_save)  {
		g_warning(udpgate_printf_alloca(_("Unable to stop the daemon at PID %d: %s"),
				(int)daemon_pid,strerror(errno_save)));
		return FALSE;
		}
ok:
	if (network_notify_hostip)
		(*network_notify_hostip)(0);
	return TRUE;
}

static GMainLoop *gmainloop;
static void network_detach_network_notify_hostip(guint32 hostip_guint32)
{
	if (!hostip_guint32)
		g_main_loop_quit(gmainloop);
}

gboolean network_detach(void)
{
pid_t daemon_pid,forked_pid;

	if ((pid_t)-1==(daemon_pid=is_daemon_running()))
		return TRUE;
	if (getpid()!=daemon_pid)
		return TRUE;
	if (!optarg_no_fork) {
		if ((pid_t)-1==(forked_pid=fork())) {
			g_warning("fork(2): %m");
			return FALSE;
			}
		if (forked_pid) {
			/* parent */
			return TRUE;
			}
		write_daemon_running(getpid());	/* errors ignored */
		optarg_verbose=0;
		close(STDIN_FILENO);
		close(STDOUT_FILENO);
		close(STDERR_FILENO);
		setpgrp();
		setsid();
		}

	network_notify_hostip=network_detach_network_notify_hostip;
	gmainloop=g_main_loop_new(
			NULL,	/* context */
			TRUE);	/* is_running; ignored */
	g_main_loop_run(gmainloop);	/* loop */
	/* Unable to contact the server, aborting. */
	return FALSE;
}