用c写了个后台扫描

/**
 * Notice: The program is not debug on internet and not use thread supervene.
 * date  : 6-26
 * author: jker 
 **/
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#define LINE 1024
#define dict "dict.txt"
#define result "manager.txt"
 
void itos(int num,char *str){
  int a=num;
  int x,y,z;
  x=a/100;
  y=a%100/10;
  z=a%10;
  if(x==0){
    if(y==0){
      str[0]+=z;
      str[1]='';
    }else{
      str[0]+=y;
      str[1]+=z;
      str[2]='';
    }
  }else{
    str[0]+=x;
    str[1]+=y;
    str[2]+=z;
    str[3]='';
  }
  return;
}
char *nip(char *oip){
  char *str[4]={""},*rtn;
  char *delim = ".";
  char * tmp;
  int i=0;
  char arr[4]={48,48,48,''};
  rtn = malloc(512);
  memset(rtn,'',512);
  tmp = strtok(oip,delim);
  str[i++]=tmp;
  while(tmp=strtok(NULL,delim)){
    str[i++]=tmp;
  }
 
  for(i=3;i>=0;i--){
    if(atoi(str[i])<255){
      itos(atoi(str[i])+1,arr);
      str[i]=arr;
      break;
    }
  }
 
  for(i=0;i<4;i++){
    strcat(rtn,str[i]);
    if(i<3)strcat(rtn,delim);
  }
 
  return rtn;
}
int main(int argc,char *argv[]){
  int sc,fd;
  unsigned short port = 80;
  struct sockaddr_in add;
  char *ip,*sip,*eip;
  struct hostent *host;
  char rheader[LINE],dictbuf[LINE],resbuf[LINE];
  char *dir,path[LINE]="",*arr[LINE],*tmp,state[3],manager[LINE];
  int i=0,n=0,bytes;
  if(argc != 3){
    printf("please input startIp and endIp.
");
    return -1;
  }
  dir = get_current_dir_name();
  strcat(path,dir);
  strcat(path,"/");
  strcat(path,dict);
  fd = open(path,O_RDONLY);
  read(fd,dictbuf,sizeof(dictbuf));
  close(fd);
  arr[n++]=strtok(dictbuf,"
");
  while(tmp=strtok(NULL,"
"))arr[n++]=tmp;
 
  ip = malloc(512);
  memset(ip,'',512);
  sip = argv[1];
  eip = argv[2];
  strcpy(ip,sip);
 
  memset(manager,'',LINE);
  memset(rheader,'',LINE);
 
  sc = socket(AF_INET,SOCK_STREAM,0);
  if(sc == -1){
    printf("create socket fail!
");
    return -1;
  }
  printf("create socket ok.
");
  bzero(&add,sizeof(add));
  add.sin_family=AF_INET;
  add.sin_port=htons(port);
  bzero(&path,sizeof(path));
  strcat(path,dir);
  strcat(path,"/");
  strcat(path,result);
  fd = open(path,O_WRONLY|O_CREAT);
 
  do{
    host = gethostbyaddr(ip,strlen(ip),AF_INET);
    if(host == (struct hostent *)NULL) {
      printf("can`t get host from %s
",ip);
      if(strcmp(ip,eip)<0)ip=nip(ip);
      continue;
    }else{                                                                              
      printf("host name:%s
",host->h_name);
    }
 
    add.sin_addr.s_addr=inet_addr(ip);
    if(connect(sc,(struct sockaddr *)(&add),sizeof(struct sockaddr))==-1){
      printf("conn fail!
");
      return -1;
    }
    for(;i<n;i++){
      strcat(rheader,"HEAD ");
      strcat(rheader,arr[i]);
      strcat(rheader," HTTP/1.1");
      strcat(rheader,"
");
      strcat(rheader,"Host:");
      strcat(rheader,host->h_name);
      strcat(rheader,"
");
 
      //strcat(rheader,"Accept:*/*");
      //strcat(rheader,"
");
      strcat(rheader,"Connection:Keep-Alive");
      strcat(rheader,"
");
      write(sc, rheader, strlen(rheader));usleep(100);        
      bytes = read(sc, resbuf, LINE);        
      printf("Response from %s:
",ip);        
      write(STDOUT_FILENO, resbuf, bytes);
      for(i=0;i<3;i++){
        state[i]=resbuf[i+9];
      }
      if(!((state>="400" && state<="450")||state=="500")){
        strcat(manager,"http://");
        strcat(manager,host->h_name);
        strcat(manager,arr[i]);
        strcat(manager,"
");
   write(fd,manager,sizeof(manager));
      }
    } 
    close(sc);
    ip = nip(ip);
  }while(strcmp(ip,eip)<0);
 
  close(fd);
  return 0;
}