问如何从udp套接字(C/C++)获取自己的(本地)IP地址

EN

    //create socket and bind to local address:INADDR_ANY:
    int s = socket(PF_INET,SOCK_DGRAM,0);
    bind(s,(struct sockaddr *)&myAddr,sizeof(myAddr)) ;
    // set option
    int onFlag=1;
    int ret = setsockopt(s,IPPROTO_IP,IP_PKTINFO,&onFlag,sizeof(onFlag));
    // prepare buffers
    // receive data buffer
    char dataBuf[1024] ;
    struct iovec iov = {
        .iov_base=dataBuf,
        .iov_len=sizeof(dataBuf)
    } ;
    // control buffer
    char cBuf[1024] ;
    // message
    struct msghdr  msg = {
        .msg_name=NULL, // to receive peer addr with struct sockaddr_in
        .msg_namelen=0, // sizeof(struct sockaddr_in)
        .msg_iov=&iov,
        .msg_iovlen=1,
        .msg_control=cBuf,
        .msg_controllen=sizeof(cBuf)
    } ;
    while(1) {
        // reset buffers
        msg.msg_iov[0].iov_base = dataBuf ;
        msg.msg_iov[0].iov_len = sizeof(dataBuf) ;
        msg.msg_control = cBuf ;
        msg.msg_controllen = sizeof(cBuf) ;
        // receive
        recvmsg(s,&msg,0);
        for( struct cmsghdr* pcmsg=CMSG_FIRSTHDR(&msg);
             pcmsg!=NULL; pcmsg=CMSG_NXTHDR(&msg,pcmsg) ) {
            if(pcmsg->cmsg_level==IPPROTO_IP && pcmsg->cmsg_type==IP_PKTINFO) {
                struct in_pktinfo * pktinfo=(struct in_pktinfo *)CMSG_DATA(pcmsg);
                printf("ifindex=%d ip=%s\n", pktinfo->ipi_ifindex, inet_ntoa(pktinfo->ipi_addr)) ;
            }
        }
    }

BOOL bOptVal = 1;
setsockopt(so, SOL_SOCKET, SO_REUSEADDR, (char *)&boOptVal, sizeof(bOptVal));

SOCKET skNew = socket( )
// Same local address and port as that of your first socket 
// INADDR_ANY
bind(skNew, ,  )
// set SO_REUSEADDR to true again
setsockopt(skNew, SOL_SOCKET, SO_REUSEADDR, (char *)&boOptVal, sizeof(bOptVal));

// connect back  
connect(skNew, remoteAddr)

// get local address of the socket
getsocketname(skNew, )