// C code:

typedef struct _rc_packet {
    int size;
    int id;
    int cmd;
    char data[DATA_BUFFSIZE];
} rc_packet;

rc_packet *packet_build(int id, int cmd, char *s1)
{   /* hacky function */
    static rc_packet packet = {0, 0, 0, { 0x00 }};

    /* size + id + cmd + s1 + s2 NULL terminator */
    int s1_len = strlen(s1);
    if(s1_len > DATA_BUFFSIZE) {
        fprintf(stderr, "Warning: Command string too long (%d). Maximum allowed: %d.\n", s1_len, DATA_BUFFSIZE);
        return NULL;
    }

    packet.size = sizeof(int) * 2 + s1_len + 2;
    packet.id = id;
    packet.cmd = cmd;
    strncpy(packet.data, s1, DATA_BUFFSIZE);

    return &packet;
}

// Java code:

public class Packet
{
	int size;
	int id;
	int cmd;
	byte data[] = new byte[10240];
	Packet()
	{
		size = id = cmd = 0;
	}
	Packet(int id, int cmd, String msg)
	{
		size = 8 + msg.getBytes().length + 2;
		this.id = id;
		this.cmd = cmd;
		data = msg.getBytes();
	}
}