1 files changed, 97 insertions, 0 deletions
diff --git a/src/rcon.c b/src/rcon.c
new file mode 100644
index 0000000..a302d12
--- /dev/null
+++ b/src/rcon.c
@@ -0,0 +1,97 @@
+/*
+ * src/rcon.c
+ * (c) 2020 Jonas Gunz <himself@jonasgunz.de>
+ * License: 
+*/
+
+/*
+ * 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 char* rcon_errors[] = {
+	"No Error.",
+	"Undefined Error.",
+	"Login Denied.",
+	"Buffer size incorrect.",
+	"Malformed packet recieved."
+};
+
+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;
+}
+
+char* rcon_strerror ( int _errno ) {
+	return _errno > 4 ? rcon_errors[1] : rcon_errors[_errno];
+}