/*
sv_filter.c - server ID/IP filter
Copyright (C) 2017 a1batross

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, either version 3 of the License, or
(at your option) any later version.

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.
*/

#include "common.h"
#include "server.h"


/*
=============================================================================

PLAYER ID FILTER

=============================================================================
*/
typedef struct cidfilter_s
{
	float endTime;
	struct cidfilter_s *next;
	string id;
} cidfilter_t;

static cidfilter_t *cidfilter = NULL;

static void SV_RemoveID( const char *id )
{
	cidfilter_t *filter, *prevfilter = NULL;

	for( filter = cidfilter; filter; filter = filter->next )
	{
		if( Q_strcmp( filter->id, id ))
		{
			prevfilter = filter;
			continue;
		}

		if( filter == cidfilter )
		{
			cidfilter = cidfilter->next;
			Mem_Free( filter );
			return;
		}

		if( prevfilter )
		prevfilter->next = filter->next;
		Mem_Free( filter );
		return;
	}
}

qboolean SV_CheckID( const char *id )
{
	qboolean ret = false;
	cidfilter_t *filter;

	for( filter = cidfilter; filter; filter = filter->next )
	{
		int len1 = Q_strlen( id ), len2 = Q_strlen( filter->id );
		int len = Q_min( len1, len2 );

		while( filter->endTime && host.realtime > filter->endTime )
		{
			char *fid = filter->id;
			filter = filter->next;
			SV_RemoveID( fid );
			if( !filter )
				return false;
		}

		if( !Q_strncmp( id, filter->id, len ))
		{
			ret = true;
			break;
		}
	}

	return ret;
}

static void SV_BanID_f( void )
{
	float time = Q_atof( Cmd_Argv( 1 ));
	const char *id = Cmd_Argv( 2 );
	sv_client_t *cl = NULL;
	cidfilter_t *filter;

	if( time )
		time = host.realtime + time * 60.0f;

	if( !id[0] )
	{
		Con_Reportf( S_USAGE "banid <minutes> <#userid or unique id>\n0 minutes for permanent ban\n" );
		return;
	}

	if( !svs.clients )
	{
		Con_Reportf( S_ERROR "banid: no players\n" );
		return;
	}

	if( id[0] == '#' )
	{
		Con_Printf( S_ERROR "banid: not supported\n" );
		return;
#if 0
		int i = Q_atoi( &id[1] );

		cl = SV_ClientById( i );

		if( !cl )
		{
			Con_Printf( S_ERROR "banid: no such player with userid %d\n", i );
			return;
		}
#endif
	}
	else
	{
		size_t len;
		int i;

		if( !Q_strnicmp( id, "STEAM_", 6 ) || !Q_strnicmp( id, "VALVE_", 6 ))
			id += 6;
		if( !Q_strnicmp( id, "XASH_", 5 ))
			id += 5;

		len = Q_strlen( id );

		for( i = 0; i < sv_maxclients.value; i++ )
		{
			if( FBitSet( svs.clients[i].flags, FCL_FAKECLIENT ))
				continue;

			if( svs.clients[i].state != cs_spawned )
				continue;

			if( !Q_strncmp( id, Info_ValueForKey( svs.clients[i].useragent, "uuid" ), len ))
			{
				cl = &svs.clients[i];
				break;
			}
		}

		if( !cl )
		{
			Con_Printf( S_ERROR "banid: no such player with userid %s\n", id );
			return;
		}
	}

	id = Info_ValueForKey( cl->useragent, "uuid" );

	SV_RemoveID( id );

	filter = Mem_Malloc( host.mempool, sizeof( cidfilter_t ));
	filter->endTime = time;
	filter->next = cidfilter;
	Q_strncpy( filter->id, id, sizeof( filter->id ));
	cidfilter = filter;

	if( cl && !Q_stricmp( Cmd_Argv( Cmd_Argc() - 1 ), "kick" ))
		Cbuf_AddTextf( "kick #%d \"Kicked and banned\"\n", cl->userid );
}

static void SV_ListID_f( void )
{
	cidfilter_t *filter;

	Con_Reportf( "id ban list\n" );
	Con_Reportf( "-----------\n" );

	for( filter = cidfilter; filter; filter = filter->next )
	{
		if( filter->endTime && host.realtime > filter->endTime )
			continue; // no negative time

		if( filter->endTime )
			Con_Reportf( "%s expries in %f minutes\n", filter->id, ( filter->endTime - host.realtime ) / 60.0f );
		else
			Con_Reportf( "%s permanent\n", filter->id );
	}
}

static void SV_RemoveID_f( void )
{
	const char *id = Cmd_Argv( 1 );

	if( id[0] == '#' && svs.clients )
	{
		int num = Q_atoi( id + 1 );

		if( num >= sv_maxclients.value || num < 0 )
			return;

		id = Info_ValueForKey( svs.clients[num].useragent, "uuid" );
	}

	if( !id[0] )
	{
		Con_Reportf( S_USAGE "removeid <#slotnumber or uniqueid>\n");
		return;
	}

	SV_RemoveID( id );
}

static void SV_WriteID_f( void )
{
	file_t *f = FS_Open( Cvar_VariableString( "bannedcfgfile" ), "w", false );
	cidfilter_t *filter;

	if( !f )
	{
		Con_DPrintf( S_ERROR "Could not write %s\n", Cvar_VariableString( "bannedcfgfile" ));
		return;
	}

	FS_Printf( f, "//=======================================================================\n" );
	FS_Printf( f, "//\t\tCopyright Flying With Gauss Team %s ©\n", Q_timestamp( TIME_YEAR_ONLY ));
	FS_Printf( f, "//\t\t    %s - archive of id blacklist\n", Cvar_VariableString( "bannedcfgfile" ));
	FS_Printf( f, "//=======================================================================\n" );

	for( filter = cidfilter; filter; filter = filter->next )
		if( !filter->endTime ) // only permanent
			FS_Printf( f, "banid 0 %s\n", filter->id );

	FS_Close( f );
}

static void SV_InitIDFilter( void )
{
	Cmd_AddRestrictedCommand( "banid", SV_BanID_f, "ban player by ID" );
	Cmd_AddRestrictedCommand( "listid", SV_ListID_f, "list banned players" );
	Cmd_AddRestrictedCommand( "removeid", SV_RemoveID_f, "remove player from banned list" );
	Cmd_AddRestrictedCommand( "writeid", SV_WriteID_f, "write banned.cfg" );
}

static void SV_ShutdownIDFilter( void )
{
	cidfilter_t *cidList, *cidNext;

	// should be called manually because banned.cfg is not executed by engine
	//SV_WriteID_f();

	Cmd_RemoveCommand( "banid" );
	Cmd_RemoveCommand( "listid" );
	Cmd_RemoveCommand( "removeid" );
	Cmd_RemoveCommand( "writeid" );

	for( cidList = cidfilter; cidList; cidList = cidNext )
	{
		cidNext = cidList->next;
		Mem_Free( cidList );
	}

	cidfilter = NULL;
}

/*
=============================================================================

CLIENT IP FILTER

=============================================================================
*/

typedef struct ipfilter_s
{
	float endTime;
	struct ipfilter_s *next;
	netadr_t adr;
	uint prefixlen;
} ipfilter_t;

static ipfilter_t *ipfilter = NULL;

static void SV_CleanExpiredIPFilters( void )
{
	ipfilter_t *f, **back;

	back = &ipfilter;
	while( 1 )
	{
		f = *back;
		if( !f ) return;

		if( f->endTime && host.realtime > f->endTime )
		{
			*back = f->next;
			back = &f->next;

			Mem_Free( f );
		}
		else back = &f->next;
	}
}

static int SV_FilterToString( char *dest, size_t size, qboolean config, ipfilter_t *f )
{
	const char *strformat;

	if( config )
	{
		return Q_snprintf( dest, size, "addip 0 %s/%d\n", NET_AdrToString( f->adr ), f->prefixlen );
	}
	else if( f->endTime )
	{
		return Q_snprintf( dest, size, "%s/%d (%f minutes)", NET_AdrToString( f->adr ), f->prefixlen, f->endTime );
	}

	return Q_snprintf( dest, size, "%s/%d (permanent)", NET_AdrToString( f->adr ), f->prefixlen );
}

static qboolean SV_IPFilterIncludesIPFilter( ipfilter_t *a, ipfilter_t *b )
{
	if( a->adr.type6 != b->adr.type6 )
		return false;

	// can't include bigger subnet in small
	if( a->prefixlen < b->prefixlen )
		return false;

	if( a->prefixlen == b->prefixlen )
		return NET_CompareAdr( a->adr, b->adr );

	return NET_CompareAdrByMask( a->adr, b->adr, b->prefixlen );
}

static void SV_RemoveIPFilter( ipfilter_t *toremove, qboolean removeAll, qboolean verbose )
{
	ipfilter_t *f, **back;

	back = &ipfilter;
	while( 1 )
	{
		f = *back;
		if( !f ) return;

		if( SV_IPFilterIncludesIPFilter( toremove, f ))
		{
			if( verbose )
			{
				string filterStr;

				SV_FilterToString( filterStr, sizeof( filterStr ), false, f );

				Con_Printf( "%s removed.\n", filterStr );
			}

			*back = f->next;
			back = &f->next;

			Mem_Free( f );

			if( !removeAll )
				break;
		}
		else back = &f->next;
	}
}


qboolean SV_CheckIP( netadr_t *adr )
{
	// TODO: ip rate limit
	ipfilter_t *entry = ipfilter;

	for( ; entry; entry = entry->next )
	{
		switch( entry->adr.type6 )
		{
		case NA_IP:
		case NA_IP6:
			if( NET_CompareAdrByMask( *adr, entry->adr, entry->prefixlen ))
				return true;
			break;
		}
	}

	return false;
}

static void SV_AddIP_PrintUsage( void )
{
	Con_Printf(S_USAGE "addip <minutes> <ipaddress>\n"
		S_USAGE_INDENT "addip <minutes> <ipaddress/CIDR>\n"
		"Use 0 minutes for permanent\n"
		"ipaddress A.B.C.D/24 is equivalent to A.B.C.0 and A.B.C\n"
		"NOTE: IPv6 addresses only support prefix format!\n");
}

static void SV_RemoveIP_PrintUsage( void )
{
	Con_Printf(S_USAGE "removeip <ipaddress> [removeAll]\n"
		S_USAGE_INDENT "removeip <ipaddress/CIDR> [removeAll]\n"
		"Use removeAll to delete all ip filters which ipaddress or ipaddress/CIDR includes\n");
}

static void SV_ListIP_PrintUsage( void )
{
	Con_Printf(S_USAGE "listip [ipaddress]\n"
		S_USAGE_INDENT  "listip [ipaddress/CIDR]\n");
}

static void SV_AddIP_f( void )
{
	const char *szMinutes = Cmd_Argv( 1 );
	const char *adr = Cmd_Argv( 2 );
	ipfilter_t filter, *newfilter;
	float minutes;
	int i;

	if( Cmd_Argc() != 3 )
	{
		// a1ba: kudos to rehlds for an idea of using CIDR prefixes
		// in these commands :)
		SV_AddIP_PrintUsage();
		return;
	}

	minutes = Q_atof( szMinutes );
	if( minutes < 0.1f )
		minutes = 0;

	if( minutes != 0.0f )
		filter.endTime = host.realtime + minutes * 60;
	else filter.endTime = 0;

	if( !NET_StringToFilterAdr( adr, &filter.adr, &filter.prefixlen ))
	{
		Con_Printf( "Invalid IP address!\n" );
		SV_AddIP_PrintUsage();
		return;
	}

	newfilter = Mem_Malloc( host.mempool, sizeof( *newfilter ));
	newfilter->endTime = filter.endTime;
	newfilter->adr = filter.adr;
	newfilter->prefixlen = filter.prefixlen;
	newfilter->next = ipfilter;

	ipfilter = newfilter;

	for( i = 0; i < svs.maxclients; i++ )
	{
		netadr_t clientadr = svs.clients[i].netchan.remote_address;

		if( !NET_CompareAdrByMask( clientadr, filter.adr, filter.prefixlen ))
			continue;

		SV_ClientPrintf( &svs.clients[i], "The server operator has added you to banned list\n" );
		SV_DropClient( &svs.clients[i], false );
	}
}

static void SV_ListIP_f( void )
{
	qboolean haveFilter = false;
	ipfilter_t filter, *f;

	if( Cmd_Argc() > 2 )
	{
		SV_ListIP_PrintUsage();
		return;
	}

	if( ipfilter == NULL )
	{
		Con_Printf( "IP filter list is empty\n" );
		return;
	}

	if( Cmd_Argc() == 2 )
	{
		haveFilter = NET_StringToFilterAdr( Cmd_Argv( 1 ), &filter.adr, &filter.prefixlen );

		if( !haveFilter )
		{
			 Con_Printf( "Invalid IP address!\n" );
			 SV_ListIP_PrintUsage();
			 return;
		}
	}

	Con_Printf( "IP filter list:\n" );

	for( f = ipfilter; f; f = f->next )
	{
		string filterStr;

		if( haveFilter && !SV_IPFilterIncludesIPFilter( &filter, f ))
			continue;

		SV_FilterToString( filterStr, sizeof( filterStr ), false, f );
		Con_Printf( "%s\n", filterStr );
	}
}

static void SV_RemoveIP_f( void )
{
	const char *adr = Cmd_Argv( 1 );
	qboolean removeAll;
	ipfilter_t filter;
	int i;

	if( Cmd_Argc() != 2 && Cmd_Argc() != 3 )
	{
		SV_RemoveIP_PrintUsage();
		return;
	}

	removeAll = Cmd_Argc() == 3 && !Q_strcmp( Cmd_Argv( 2 ), "removeAll" );

	if( !NET_StringToFilterAdr( adr, &filter.adr, &filter.prefixlen ))
	{
		Con_Printf( "Invalid IP address!\n" );
		SV_RemoveIP_PrintUsage();
		return;
	}

	SV_RemoveIPFilter( &filter, removeAll, true );
}

static void SV_WriteIP_f( void )
{
	file_t *fd = FS_Open( Cvar_VariableString( "listipcfgfile" ), "w", true );
	ipfilter_t *f;

	if( !fd )
	{
		Con_Printf( "Couldn't open listip.cfg\n" );
		return;
	}

	for( f = ipfilter; f; f = f->next )
	{
		string filterStr;
		int size;

		// do not save temporary bans
		if( f->endTime )
			continue;

		size = SV_FilterToString( filterStr, sizeof( filterStr ), true, f );
		FS_Write( fd, filterStr, size );
	}

	FS_Close( fd );
}

static void SV_InitIPFilter( void )
{
	Cmd_AddRestrictedCommand( "addip", SV_AddIP_f, "add entry to IP filter" );
	Cmd_AddRestrictedCommand( "listip", SV_ListIP_f, "list current IP filter" );
	Cmd_AddRestrictedCommand( "removeip", SV_RemoveIP_f, "remove IP filter" );
	Cmd_AddRestrictedCommand( "writeip", SV_WriteIP_f, "write listip.cfg" );
}

static void SV_ShutdownIPFilter( void )
{
	ipfilter_t *ipList, *ipNext;

	// should be called manually because banned.cfg is not executed by engine
	//SV_WriteIP_f();

	for( ipList = ipfilter; ipList; ipList = ipNext )
	{
		ipNext = ipList->next;
		Mem_Free( ipList );
	}

	ipfilter = NULL;
}

void SV_InitFilter( void )
{
	SV_InitIPFilter();
	SV_InitIDFilter();
}

void SV_ShutdownFilter( void )
{
	SV_ShutdownIPFilter();
	SV_ShutdownIDFilter();
}

#if XASH_ENGINE_TESTS

#include "tests.h"

void Test_StringToFilterAdr( void )
{
	ipfilter_t f1;
	int i;
	struct
	{
		const char *str;
		qboolean valid;
		int prefixlen;
		int a, b, c, d;
	} ipv4tests[] =
	{
	{ "127.0.0.0/8", true, 8, 127, 0, 0, 0 },
	{ "192.168",     true, 16, 192, 168, 0, 0 },
	{ "192.168/23",  true, 23, 192, 168, 0, 0 },
	{ "192.168./23", true, 23, 192, 168, 0, 0 },
	{ "192.168../23", true, 23, 192, 168, 0, 0 },
	{ "..192...168/23", false },
	{ "", false },
	{ "abcd", false }
	};
	struct
	{
		const char *str;
		qboolean valid;
		int prefixlen;
		uint8_t x[16];
	} ipv6tests[] =
	{
	{ "::1", true, 128, { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 } },
	{ "fd18:b9d4:65cf:83de::/64", true, 64, { 0xfd, 0x18, 0xb9, 0xd4, 0x65, 0xcf, 0x83, 0xde } },
	{ "kkljnljkhfjnkj", false },
	{ "fd8a:63d5:e014:0d62:ffff:ffff:ffff:ffff:ffff", false },
	};

	for( i = 0; i < ARRAYSIZE( ipv4tests ); i++ )
	{
		qboolean ret = NET_StringToFilterAdr( ipv4tests[i].str, &f1.adr, &f1.prefixlen );

		TASSERT_EQi( ret, ipv4tests[i].valid );

		if( ret )
		{
			TASSERT_EQi( f1.prefixlen, ipv4tests[i].prefixlen );
			TASSERT_EQi( f1.adr.ip[0], ipv4tests[i].a );
			TASSERT_EQi( f1.adr.ip[1], ipv4tests[i].b );
			TASSERT_EQi( f1.adr.ip[2], ipv4tests[i].c );
			TASSERT_EQi( f1.adr.ip[3], ipv4tests[i].d );
		}
	}

	for( i = 0; i < ARRAYSIZE( ipv6tests ); i++ )
	{
		qboolean ret = NET_StringToFilterAdr( ipv6tests[i].str, &f1.adr, &f1.prefixlen );
		uint8_t x[16];

		TASSERT_EQi( ret, ipv6tests[i].valid );

		if( ret )
		{
			TASSERT_EQi( f1.prefixlen, ipv6tests[i].prefixlen );

			NET_NetadrToIP6Bytes( (uint8_t*)x, &f1.adr );

			TASSERT( memcmp( x, ipv6tests[i].x, sizeof( x )) == 0 );
		}
	}
}

void Test_IPFilterIncludesIPFilter( void )
{
	qboolean ret;
	const char *adrs[] =
	{
		"127.0.0.1/8", // 0
		"127.0.0.1", // 1
		"192.168/16", // 2
		"fe80::/64", // 3
		"fe80::96ab:9a49:2944:1808", // 4
		"2a00:1370:8190:f9eb::/62", // 5
		"2a00:1370:8190:f9eb:3866:6126:330c:b82b" // 6
	};
	ipfilter_t f[7];
	int i;
	int tests[][3] =
	{
		// ipv4
		{ 0, 0, true },
		{ 0, 1, false },
		{ 1, 0, true },
		{ 0, 2, false },
		{ 2, 0, false },

		// mixed
		{ 0, 3, false },
		{ 1, 4, false },

		// ipv6
		{ 3, 3, true },
		{ 3, 4, false },
		{ 4, 3, true },
		{ 5, 3, false },
		{ 3, 5, false },
		{ 6, 5, true },
	};

	for( i = 0; i < 7; i++ )
	{
		NET_StringToFilterAdr( adrs[i], &f[i].adr, &f[i].prefixlen );
	}

	for( i = 0; i < ARRAYSIZE( tests ); i++ )
	{
		ret = SV_IPFilterIncludesIPFilter( &f[tests[i][0]], &f[tests[i][1]] );

		TASSERT_EQi( ret, tests[i][2] );
	}
}

void Test_RunIPFilter( void )
{
	Test_StringToFilterAdr();
	Test_IPFilterIncludesIPFilter();
}

#endif // XASH_ENGINE_TESTS