Why "bad address" at ioctl() call - c++

Question

I recently develop a program to wrap CAN bus feature into a class so it will be more reusable in future. I try to separate codes from long-single-file into main, header and implementation files.
So I have 3 files, "canbus.cpp", "canbus.h" and "main.cpp". Here are my code snippet:
canbus.h
#ifndef CANBUS_H
#define CANBUS_H
#include ... (some includes go here)
class CANBUS{
int CANbusSocket = 0; // Canbus socket number which is gained at initiation process by linux socket() function call.
const char* CANbusInterfaceName;
int CANbusReadMode;
struct can_frame frame;
struct ifreq ifr;
struct sockaddr_can addr;
can_err_mask_t err_mask;
public:
// canbus mode mode: 0-listen only, 1-request pgn
// canbus interface name: "can0", "can1"
CANBUS(int mode=0, const char* name="can1");
int init();
};
#endif
canbus.cpp
#include "canbus.h"
#include <iostream>
// Constructor
CANBUS::CANBUS(int mode, const char* name){
CANbusReadMode = mode;
CANbusInterfaceName = name;
}
int CANBUS::init(){
CANbusSocket = socket(PF_CAN, SOCK_RAW, CAN_RAW);
if( CANbusSocket == -1){
std::cout<<CANbusSocket<<std::endl;
fprintf(stderr, "Error socket: %s\n", strerror( errno ));
}
strcpy(ifr.ifr_name, CANbusInterfaceName );
if(ioctl(CANbusSocket, SIOCGIFINDEX, ifr) != 0){
std::cout<<CANbusSocket<<std::endl;
fprintf(stderr, "Error ioctl: %s\n", strerror( errno ));
}
addr.can_family = AF_CAN;
addr.can_ifindex = ifr.ifr_ifindex;
if(bind(CANbusSocket, (struct sockaddr *)&addr, sizeof(addr)) !=0){
std::cout<<CANbusSocket<<std::endl;
fprintf(stderr, "Error bind: %s\n", strerror( errno ));
}
if(setsockopt(CANbusSocket, SOL_CAN_RAW, CAN_RAW_ERR_FILTER, &err_mask, sizeof(err_mask))){ // enable error message frame
std::cout<<CANbusSocket<<std::endl;
fprintf(stderr, "Error setsockopt: %s\n", strerror( errno ));
}
return 0;
}
main.cpp
#include "canbus.h"
#include <iostream>
int main(){
errno = 0;
const char* interfaceName = "can1";
int readMode = 0;
CANBUS can1(readMode, interfaceName);
can1.init();
// ... some codes here
return 0;
}
when I build with g++ and then run it, it will give error at ioctl() like this:
Error ioctl: Bad address
To note:
This kind program works previously which was written in the previous long-single-file code
Sequence in CANbus::init() is exactly the same order as previous code
variable for socket is now private while it was public in old
code
variable for socket is now accessed/assigned directly in CANbus::init() function while it was passed as pointer in previous CANbus::init(int* CANbusSocket) function
I've also tried to change CANbusSocket inside CANbus::init() from variable to pointer, but it gave me
Segmentation Fault