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我正在使用pcap和无线方式处理项目。根据我之前提出的问题发布的示例，我尝试从无线帧中提取MAC地址。我已经为radiotap头文件和基本管理框架创建了结构。出于某种原因，当试图输出MAC地址时，我正在输出错误的数据。当我比较Wireshark时，我不明白为什么无线电窃听数据正确输出，但是MAC地址不是。当我查看数据包并比较我捕获的数据包时，在Wireshark显示的十六进制转储中没有看到任何附加填充。我有点儿有c，但不是专家，所以也许我没有正确使用指针和结构，有人可以帮我看看我做错了什么？使用pcap处理来自802.11帧的不正确mac地址
感谢， 昆汀
// main.c
// MacSniffer
//
#include <pcap.h>
#include <string.h>
#include <stdlib.h>
#define MAXBYTES2CAPTURE 65535
#ifdef WORDS_BIGENDIAN
typedef struct frame_control
{
unsigned int subtype:4; /*frame subtype field*/
unsigned int protoVer:2; /*frame type field*/
unsigned int version:2; /*protocol version*/
unsigned int order:1;
unsigned int protected:1;
unsigned int moreDate:1;
unsigned int power_management:1;
unsigned int retry:1;
unsigned int moreFrag:1;
unsigned int fromDS:1;
unsigned int toDS:1;
}frame_control;
struct ieee80211_radiotap_header{
u_int8_t it_version;
u_int8_t it_pad;
u_int16_t it_len;
u_int32_t it_present;
u_int64_t MAC_timestamp;
u_int8_t flags;
u_int8_t dataRate;
u_int16_t channelfrequency;
u_int16_t channFreq_pad;
u_int16_t channelType;
u_int16_t channType_pad;
u_int8_t ssiSignal;
u_int8_t ssiNoise;
u_int8_t antenna;
};
#else
typedef struct frame_control
{
unsigned int protoVer:2; /* protocol version*/
unsigned int type:2; /*frame type field (Management,Control,Data)*/
unsigned int subtype:4; /* frame subtype*/
unsigned int toDS:1; /* frame coming from Distribution system */
unsigned int fromDS:1; /*frame coming from Distribution system */
unsigned int moreFrag:1; /* More fragments?*/
unsigned int retry:1; /*was this frame retransmitted*/
unsigned int powMgt:1; /*Power Management*/
unsigned int moreDate:1; /*More Date*/
unsigned int protectedData:1; /*Protected Data*/
unsigned int order:1; /*Order*/
}frame_control;
struct ieee80211_radiotap_header{
u_int8_t it_version;
u_int8_t it_pad;
u_int16_t it_len;
u_int32_t it_present;
u_int64_t MAC_timestamp;
u_int8_t flags;
u_int8_t dataRate;
u_int16_t channelfrequency;
u_int16_t channelType;
int ssiSignal:8;
int ssiNoise:8;
};
#endif
struct wi_frame {
u_int16_t fc;
u_int16_t wi_duration;
u_int8_t wi_add1[6];
u_int8_t wi_add2[6];
u_int8_t wi_add3[6];
u_int16_t wi_sequenceControl;
// u_int8_t wi_add4[6];
//unsigned int qosControl:2;
//unsigned int frameBody[23124];
};
void processPacket(u_char *arg, const struct pcap_pkthdr* pkthdr, const u_char* packet)
{
int i= 0, *counter = (int *) arg;
struct ieee80211_radiotap_header *rh =(struct ieee80211_radiotap_header *)packet;
struct wi_frame *fr= (struct wi_frame *)(packet + rh->it_len);
u_char *ptr;
//printf("Frame Type: %d",fr->wi_fC->type);
printf("Packet count: %d\n", ++(*counter));
printf("Received Packet Size: %d\n", pkthdr->len);
if(rh->it_version != NULL)
{
printf("Radiotap Version: %d\n",rh->it_version);
}
if(rh->it_pad!=NULL)
{
printf("Radiotap Pad: %d\n",rh->it_pad);
}
if(rh->it_len != NULL)
{
printf("Radiotap Length: %d\n",rh->it_len);
}
if(rh->it_present != NULL)
{
printf("Radiotap Present: %c\n",rh->it_present);
}
if(rh->MAC_timestamp != NULL)
{
printf("Radiotap Timestamp: %u\n",rh->MAC_timestamp);
}
if(rh->dataRate != NULL)
{
printf("Radiotap Data Rate: %u\n",rh->dataRate);
}
if(rh->channelfrequency != NULL)
{
printf("Radiotap Channel Freq: %u\n",rh->channelfrequency);
}
if(rh->channelType != NULL)
{
printf("Radiotap Channel Type: %06x\n",rh->channelType);
}
if(rh->ssiSignal != NULL)
{
printf("Radiotap SSI signal: %d\n",rh->ssiSignal);
}
if(rh->ssiNoise != NULL)
{
printf("Radiotap SSI Noise: %d\n",rh->ssiNoise);
}
ptr = fr->wi_add1;
int k= 6;
printf("Destination Address:");
do{
printf("%s%X",(k==6)?" ":":",*ptr++);
}
while(--k>0);
printf("\n");
ptr = fr->wi_add2;
k=0;
printf("Source Address:");
do{
printf("%s%X",(k==6)?" ":":",*ptr++);
}while(--k>0);
printf("\n");
ptr = fr->wi_add3;
k=0;
do{
printf("%s%X",(k==6)?" ":":",*ptr++);
}
while(--k>0);
printf("\n");
/* for(int j = 0; j < 23124;j++)
{
if(fr->frameBody[j]!= NULL)
{
printf("%x",fr->frameBody[j]);
}
}
*/
for (i = 0;i<pkthdr->len;i++)
{
if(isprint(packet[i +rh->it_len]))
{
printf("%c",packet[i + rh->it_len]);
}
else{printf(".");}
//print newline after each section of the packet
if((i%16 ==0 && i!=0) ||(i==pkthdr->len-1))
{
printf("\n");
}
}
return;
}
int main(int argc, char** argv)
{
int count = 0;
pcap_t* descr = NULL;
char errbuf[PCAP_ERRBUF_SIZE], *device = NULL;
struct bpf_program fp;
char filter[]="wlan broadcast";
const u_char* packet;
memset(errbuf,0,PCAP_ERRBUF_SIZE);
device = argv[1];
if(device == NULL)
{
fprintf(stdout,"Supply a device name ");
}
descr = pcap_create(device,errbuf);
pcap_set_rfmon(descr,1);
pcap_set_promisc(descr,1);
pcap_set_snaplen(descr,30);
pcap_set_timeout(descr,10000);
pcap_activate(descr);
int dl =pcap_datalink(descr);
printf("The Data Link type is %s",pcap_datalink_val_to_name(dl));
//pcap_dispatch(descr,MAXBYTES2CAPTURE,1,512,errbuf);
//Open device in promiscuous mode
//descr = pcap_open_live(device,MAXBYTES2CAPTURE,1,512,errbuf);
/* if(pcap_compile(descr,&fp,filter,0,PCAP_NETMASK_UNKNOWN)==-1)
{
fprintf(stderr,"Error compiling filter\n");
exit(1);
}
if(pcap_setfilter(descr,&fp)==-1)
{
fprintf(stderr,"Error setting filter\n");
exit(1);
}
*/
pcap_loop(descr,0, processPacket, (u_char *) &count);
return 0;
}
我没有为Mac编码，并且通常在查找相关行时遇到了一些问题。但是我最近在pcap上发布了一个问题，得到了一个答案，在2.下，可能会有一些适用于您的问题。也许看看。 – gnometorule
打印'fr-> wi_add2'和'fr-> wi_add3'之前将'k'重置为'6'而不是'0'可能会有所帮助，但我不知道这是否是唯一的问题，因为“打印出错误的数据“不是很具体。示例数据包十六进制转储和相应的“错误”输出将很有用。 –
感谢您的意见 – dudebrobro