c - 在 pcap_creat 和 pcap_set_rfmon 之后使用 pcap 库，pcap_loop 中的处理程序不起作用

Question

#include <pcap.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netinet/if_ether.h> 
#include <net/ethernet.h>
#include <netinet/ether.h> 

struct usf
 {
  u_int8_t  dest[6];    /* destination eth addr */
  u_int8_t  source[6];  /* source ether addr    */
  u_int16_t type;
  u_int8_t  tst[6]; /* source ether addr    */
 };

 u_int16_t handle_ethernet
      (u_char *args,const struct pcap_pkthdr* pkthdr,const u_char* packet);

 void my_callback(u_char *args,const struct pcap_pkthdr* pkthdr,
                  const u_char* packet)
 {
   printf ("in my_callback function\n");
   u_int16_t type = handle_ethernet(args,pkthdr,packet);
   if(type == ETHERTYPE_IP)
   {/* handle IP packet */
   }else if(type == ETHERTYPE_ARP)
   {/* handle arp packet */
   }
   else if(type == ETHERTYPE_REVARP)
   {/* handle reverse arp packet */
   }
 }

 u_int16_t handle_ethernet
     (u_char *args,const struct pcap_pkthdr* pkthdr,
      const u_char* packet)
 {
   struct usf *eptr;  /* net/ethernet.h */
   /* lets start with the ether header... */
   eptr = (struct usf *) packet;
   fprintf(stdout,"ethernet header source: %s\n"
          ,ether_ntoa((const struct ether_addr *)&eptr->source));
   fprintf(stdout," destination: %s \n"
         ,ether_ntoa((const struct ether_addr *)&eptr->dest));
   fprintf(stdout," tst : %s\n "
         ,ether_ntoa((const struct ether_addr *)&eptr->tst));
   /* check to see if we have an ip packet */
   if (ntohs (eptr->type) == ETHERTYPE_IP)
   {
     fprintf(stdout,"(IP)");
   }else  if (ntohs (eptr->type) == ETHERTYPE_ARP)
   {
     fprintf(stdout,"(ARP)");
    }else  if (ntohs (eptr->type) == ETHERTYPE_REVARP)
    {
      fprintf(stdout,"(RARP)");
    }else {
      fprintf(stdout,"(?)");
      exit(1);
    }
  return eptr->type;
 }

 int main(int argc,char **argv)
 { 
   char *dev; // interface name ex: wlan0
   char errbuf[PCAP_ERRBUF_SIZE];
   pcap_t* descr;
   struct bpf_program fp;      /* hold compiled program     */
   bpf_u_int32 maskp;          /* subnet mask               */
   bpf_u_int32 netp;           /* ip                        */
   u_char* args = NULL;

   if(argc < 2){ 
    fprintf(stdout,"Usage: %s numpackets \"options\"\n",argv[0]);
    return 0;
   }
   /* grab a device to peak into... */
   //    dev = pcap_lookupdev(errbuf);
   dev = "wlan0";
   if(dev == NULL)
   { printf("%s\n",errbuf); exit(1); }
   /* ask pcap for the network address and mask of the device */
   pcap_lookupnet(dev,&netp,&maskp,errbuf);// return the ip of wlan0 and netmask 
   /* open device for reading. NOTE: defaulting to
    * promiscuous mode*/
   descr = pcap_create(dev,errbuf);
   // descr = pcap_open_live(dev,BUFSIZ,1,-1,errbuf);
   if(descr == NULL)
   { printf("pcap_open_live(): %s\n",errbuf); exit(1); }
   if(pcap_set_rfmon(descr,1)!=0 )
   {
     printf("monitor mode enabled: %s\n",errbuf); exit(1); 
   }
   pcap_activate(descr);
   if(argc > 2)
   {
     if(pcap_compile(descr,&fp,argv[2],0,netp) == -1)
     { fprintf(stderr,"Error calling pcap_compile\n"); exit(1); }

     if(pcap_setfilter(descr,&fp) == -1)
     { fprintf(stderr,"Error setting filter\n"); exit(1); }
   }
   int i=    pcap_loop(descr,atoi(argv[1]),my_callback,args);
   if(i==-1) 
   { 
     printf("error in pcap_loop\n"); exit(1); 
   }
   else if (i==0)
   {
     printf("   0    \n"); exit(1); 
   }
   else if (i==-2)
   {
     printf("   -2    \n"); exit(1); 
   }
   fprintf(stdout,"\nfinished\n");
   return 0;
 }

我需要做的就是将我的卡接口(interface)转换为监视模式，以嗅探信标帧以达到某些良好的目的，但是当在 pcap_creat 和 pcap_set_rfmon 之后使用 pcap 库时，pcap_loop 中的处理程序不起作用，所以任何人都可以帮助我知道什么问题是？？

Answer 1

您可以使用libiw获取/设置有关无线接口(interface)​​的信息(由iwconfig 命令使用)。