scan multiple ip

scan multiple ip

/* compile with gcc -Wall -Wextra -ggdb -pedantic -o scantest scantest.c */
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/select.h>
#include <sys/time.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <errno.h>

#define MAX_FD 30
#define PORT 21


int main(int argc,char *argv[])
{
  unsigned long ip, temp;
  struct sockaddr_in sin;
  int n,err;
  unsigned int len;
  int max=0;
  fd_set fd_group;
  struct timeval timeout;
  
  struct ip_fd
  {
    unsigned long ip;
    int fd;
  } tab_ip[MAX_FD];
  
  len=sizeof(err);

  if(argc!=2)
  {
    printf("Usage: %s <ip_addr>\n",argv[0]);
    exit(1);
  }

  if((ip=inet_addr(argv[1]))==INADDR_NONE)
  {
    printf("Adresse ip invalide!\n");
    exit(1);
  }
  temp=htonl(ip);
  sin.sin_port=htons(PORT);
  sin.sin_family=AF_INET;
  timeout.tv_sec=1;
  timeout.tv_usec=0;
  FD_ZERO(&fd_group);
  for(n=0;n<MAX_FD;n++)
  {
    ip=ntohl(temp);
    tab_ip[n].ip=ip;
    tab_ip[n].fd=socket(PF_INET,SOCK_STREAM,0);
    max=((max>(tab_ip[n].fd))?max:(tab_ip[n].fd));
    sin.sin_addr.s_addr=ip;
    fcntl(tab_ip[n].fd,F_SETFL,O_NONBLOCK);
    if((connect(tab_ip[n].fd,(struct sockaddr*)&sin,sizeof(sin)))==-1)
    {
      if(errno!=EINPROGRESS)
      {
	close(tab_ip[n].fd);
	temp++;
	continue;
      }
    }
    FD_SET(tab_ip[n].fd,&fd_group);
    temp++;
  }
  select(max+1,NULL,&fd_group,NULL,&timeout);
  for(n=0;n<MAX_FD;n++)
  {
    if(FD_ISSET(tab_ip[n].fd,&fd_group))
    {
      getsockopt(tab_ip[n].fd,SOL_SOCKET,SO_ERROR,&err,&len);
      sin.sin_addr.s_addr=tab_ip[n].ip;
      if(err==0)
      {
	printf("err=%u\n",err);
	printf("Port ouvert sur %s\n",inet_ntoa(sin.sin_addr));
	close(tab_ip[n].fd);
      }
    }
  }
	
  return 0;
}