调用pcap_findalldevs（）时，device为NULL（winpcap） [英] device is NULL when pcap_findalldevs() is called (winpcap)

问题描述

您好！



我正在尝试使用Visual Studio 2013的MFC程序中的winpcap。



当调用pcap_findalldevs（& alldevs，errbuf）时，其返回值为0，但alldevs为NULL。



下面的代码是函数的开头。



如何解决问题？

Hello!

I'm trying winpcap in MFC program of Visual Studio 2013.

When pcap_findalldevs(&alldevs, errbuf) is called, its return value is 0, but alldevs is NULL.

The code below is the very start of a function.

How can I solve the problem?

ETHER_HDR *ethhdr;
IPV4_HDR *iphdr;
TCP_HDR *tcpheader;
UDP_HDR *udpheader;
unsigned char *pkt_data;
unsigned char *data;
char errbuf[PCAP_ERRBUF_SIZE];
pcap_if_t *alldevs, *dev;
pcap_t *fp;
struct pcap_pkthdr *header;
int res = 0;
int iphdrlen = 0;
int data_size = 0;

if (pcap_findalldevs(&alldevs, errbuf) == -1)
{
    CString msg;
    msg.Format("Error in pcap_findalldevs: %s", errbuf);
    dlg->MessageBox(msg);
    return -1;
}

推荐答案

如果pcap_findalldevs找不到设备，它将成功返回0，如果有的话您可能没有权限访问的设备。



请参阅：



http：//www.tcpdump .org / manpages / pcap_findalldevs.3pcap.html



如果pcap_findalldevs（）成功，alldevsp指向的指针将设置为指向列表的第一个元素，如果没有找到设备，则为NULL（这被认为是成功）。

If pcap_findalldevs does not find a device it will return 0 as successful, if there are devices you may not have privilege to access.

See :

http://www.tcpdump.org/manpages/pcap_findalldevs.3pcap.html

"If pcap_findalldevs() succeeds, the pointer pointed to by alldevsp is set to point to the first element of the list, or to NULL if no devices were found (this is considered success)."

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