mon.c

//use "gcc mon.c -lgdi32 -lIphlpapi -lws2_32 -o mon.exe"
#include <stdio.h>

#include <math.h>
#include <process.h>
#include <winsock2.h>
#include <iphlpapi.h>
#include <icmpapi.h>
#include <stdio.h>
#include <windows.h>

#define GREEN 0
#define RED -1
#define YELLOW 1
#define WHITE 2

char *ip;
int stage = WHITE;
COLORREF crColor=RGB(255,255,255);
int x = 233;
int y = 233;
HWND hDesktopWindow;
HDC hDC;

void get_color(){
    switch(stage){
        case WHITE: crColor=RGB(255,255,255);break;
        case RED:   crColor=RGB(255,0,0);break;
        case YELLOW:crColor=RGB(255,255,0);break;
        case GREEN: crColor=RGB(0,255,0);break;
        default:    break;
    }
}

int check_ip(char *str){
    int i=0,count = 0;
    for(;i<strlen(str);i++){
        if(!(str[i]>='0'&&str[i]<='9')){
            if(str[i]=='.'){
                count++;
                continue;
            }
            return 0;
        }
    }
    if(count==3)
        return 1;
    else
        return 0;
}

char *get_host(char *host_name){
    int ret;
    struct hostent *host;
    struct in_addr addr;
    WSADATA wsaData;
    ret = WSAStartup( 0x101 , &wsaData);
    if( ret != 0 )
    {
        return "ERROR";
    }
    host = gethostbyname(host_name);
    if( host == NULL )
    {
        return "ERROR";
    }
    addr.s_addr = *(unsigned long * )host->h_addr;
    char* to_return=(char*)malloc(sizeof(inet_ntoa(addr))*sizeof(char));
    strcpy(to_return,inet_ntoa(addr)); 
    WSACleanup();
    return to_return;
}

int icmp_echo(){
    HANDLE hIcmpFile;
    unsigned long ipaddr = INADDR_NONE;
    DWORD dwRetVal = 0;
    char SendData[32] = "Nyan";
    LPVOID ReplyBuffer = NULL;
    DWORD ReplySize = 0;
    ipaddr = inet_addr(ip);
    if (ipaddr == INADDR_NONE) {
        return -1;
    }
    hIcmpFile = IcmpCreateFile();
    if (hIcmpFile == INVALID_HANDLE_VALUE) {
        return -1;
    }
    ReplySize = sizeof(ICMP_ECHO_REPLY) + sizeof(SendData);
    ReplyBuffer = (VOID*) malloc(ReplySize);
    if (ReplyBuffer == NULL) {
        return -1;
    }

    dwRetVal = IcmpSendEcho(hIcmpFile, ipaddr, SendData, sizeof(SendData), 
        NULL, ReplyBuffer, ReplySize, 1000);
    if (dwRetVal != 0) {
        PICMP_ECHO_REPLY pEchoReply = (PICMP_ECHO_REPLY)ReplyBuffer;
        struct in_addr ReplyAddr;
        ReplyAddr.S_un.S_addr = pEchoReply->Address;
        return (int)pEchoReply->RoundTripTime;
    }
    else {
        return -1;
    }
    return -1;
}

void use_icmp_echo(){
    while(1){
        sleep(1);
        int stage_ = icmp_echo();
        if(stage_==-1){
            stage = RED;
        }
        if(stage_>128+32){
            stage = YELLOW;
        }
        if(stage_>0&&stage_<128+32){
            stage = GREEN;
        }
    }
}

void use_display(){
    while(1){
        get_color();
        SetPixel(hDC, x+0, y+0, crColor);
        SetPixel(hDC, x+0, y+1, crColor);
        SetPixel(hDC, x+0, y+2, crColor);
        SetPixel(hDC, x+1, y+0, crColor);
        SetPixel(hDC, x+1, y+1, crColor);
        SetPixel(hDC, x+1, y+2, crColor);
        SetPixel(hDC, x+2, y+0, crColor);
        SetPixel(hDC, x+2, y+1, crColor);
        SetPixel(hDC, x+2, y+2, crColor);
    }
}

int main(int argc, char **argv){

    if(argc<4){
        printf("Please use \"command ip x y\".\n");
        exit(-1);
    }
    
    x = atoi(argv[2]);
    y = atoi(argv[3]);

    ip=(char *)malloc(sizeof(char)*(16+4));
    ip=strcpy(ip,argv[1]);

    hDesktopWindow = GetDesktopWindow();
    hDC = GetDC(hDesktopWindow);

    HANDLE handles[2];
    handles[0] = _beginthread(use_icmp_echo, 0, 0);
    handles[1] = _beginthread(use_display, 0, 0);

    WaitForMultipleObjects(2, handles, TRUE, INFINITE);
    return 0;

}