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/*
* src/rcon.c
* (c) 2020 Jonas Gunz <himself@jonasgunz.de>
* License: MIT
*/
/*
* Length int Length of remainder of packet
* Request ID int Client-generated ID
* Type int 3 for login, 2 to run a command, 0 for a multi-packet response
* Payload byte[] ASCII text
* 2-byte pad byte^2 Two null bytes
*
* sizeof int: 4B
* Little Endian
*
* LOGIN 3
* LOGINFAIL -1
* COMMAND 2
* RESPONSE 0
*/
#include "rcon.h"
static const unsigned int rcon_errors_len = 6;
static const char* rcon_errors[] = {
"OK",
"Undefined error",
"Authentification failed",
"Inadequate buffer",
"Packet format error",
"Connection timed out"
};
static int rcon_write_int ( char* _buffer, int _len, int32_t _data ) {
if ( _len < 4 )
return -1;
for (int i = 0; i < 4; i++)
_buffer[i] = (char)(_data >> (i*8));
return 4;
}
static int rcon_read_int ( char* _buffer, int _len, int32_t* _out ) {
if ( _len < 4 )
return -1;
*_out = 0;
for (int i = 0; i < 4; i++)
*_out |= (int32_t)((int32_t)_buffer[i] << (i*8));
return 4;
}
int rcon_parse_packet ( rcon_packet_t* _packet, char* _buffer, uint32_t _len ) {
if ( _len < 14 )
return -1;
int32_t bytecount = 0;
bytecount += rcon_read_int ( _buffer + bytecount, _len - bytecount, &_packet->length );
bytecount += rcon_read_int ( _buffer + bytecount, _len - bytecount, &_packet->id );
bytecount += rcon_read_int ( _buffer + bytecount, _len - bytecount, &_packet->type );
int32_t payload_len = _len - bytecount - 2;
_packet->payload_len = payload_len;
_packet->payload = malloc(payload_len);
memcpy ( _packet->payload, _buffer + bytecount, payload_len );
bytecount += payload_len;
bytecount += 2; // padding
//TODO check validity
return bytecount;
}
int rcon_construct_packet ( char* _buffer, uint32_t _len, rcon_packet_t* _packet ) {
if ( _len < RCON_SEND_PKGSIZE )
return -1; // Payload does not fit.
int32_t bytecount = 0;
_packet->length = _packet->payload_len + 10;
bytecount += rcon_write_int ( _buffer + bytecount, _len - bytecount, _packet->length );
bytecount += rcon_write_int ( _buffer + bytecount, _len - bytecount, _packet->id );
bytecount += rcon_write_int ( _buffer + bytecount, _len - bytecount, _packet->type );
memcpy ( _buffer + bytecount, _packet->payload, _packet->payload_len );
bytecount += _packet->payload_len;
memcpy ( _buffer + bytecount, "\0\0", 2);
bytecount += 2;
return bytecount;
}
const char* rcon_strerror ( int _errno ) {
return _errno >= rcon_errors_len ? rcon_errors[1] : rcon_errors[_errno];
}
// For packets created by rcon_parse_packet()
void rcon_free_packet ( rcon_packet_t* _packet ) {
if ( ! _packet || ! _packet->payload )
return;
free ( _packet->payload );
_packet->payload = NULL;
_packet->payload_len = 0;
}
//returns 0 on success
int rcon_send_packet ( int _socket, rcon_packet_t* _packet ) {
char buff [ RCON_SEND_PKGSIZE ];
int ret;
if ( _socket < 0 || !_packet )
return RCON_ERR_GENERIC;
if( ! ((ret = rcon_construct_packet ( buff, RCON_SEND_PKGSIZE, _packet )) > 0) )
return RCON_ERR_PACKET;
if ( send ( _socket, buff, ret, 0 ) > 0 )
return 0;
return RCON_ERR_GENERIC;
}
//returns 0 on success
int rcon_recv_packet ( int _socket, rcon_packet_t* _packet, int _timeout_msecs ) {
char buff [ RCON_SEND_PKGSIZE ];
int ret;
struct pollfd fds;
if ( _socket < 0 || !_packet )
return RCON_ERR_GENERIC;
fds.fd = _socket;
fds.events = POLLIN;
ret = poll ( &fds, 1, _timeout_msecs );
if ( ret > 0 && fds.revents & POLLIN) {
ret = recv ( _socket, buff, RCON_RECV_PKGSIZE, 0 );
if ( ! (rcon_parse_packet ( _packet, buff, ret ) > 0) )
return RCON_ERR_PACKET;
return 0;
}
return RCON_ERR_TIMEOUT; //timeout
}
int rcon_login ( int _socket, const char* _password ) {
int ret;
rcon_packet_t result, request = {
0,
1337, // TODO remove hardcoded ID
RCON_LOGIN,
(char*) _password,
strlen(_password)
};
if ( _socket < 0 || !_password )
return RCON_ERR_GENERIC;
if ( (ret = rcon_send_packet ( _socket, &request )) )
return ret;
if ( (ret = rcon_recv_packet ( _socket, &result, 1000 )) )
return ret;
if ( result.type != RCON_COMMAND || result.id != 1337 )
return RCON_ERR_AUTH;
return 0;
}
int rcon_command ( char** _output, int _socket, const char* _command ) {
int ret;
if ( _socket < 0 || !_command )
return RCON_ERR_GENERIC;
rcon_packet_t result, request = {
0,
1337, // TODO remove hardcoded ID
RCON_COMMAND,
(char*) _command, //NONONONONONONONONONONO
strlen(_command)
};
if ( (ret = rcon_send_packet ( _socket, &request )) )
return ret;
if ( (ret = rcon_recv_packet ( _socket, &result, 1000 )) )
return ret;
// TODO truncated response
*_output = malloc ( result.payload_len + 1 );
*_output[result.payload_len] = 0;
memcpy ( *_output, result.payload, result.payload_len );
rcon_free_packet ( &result );
if ( result.type != RCON_RESPONSE || result.id != 1337 )
return RCON_ERR_PACKET;
return 0;
}
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