什么是pcap_pkthdr那里？ [英] What's pcap_pkthdr there for?

问题描述

code段从这里：

void packet_handler(u_char *param, const struct pcap_pkthdr *header, const u_char *pkt_data) 
{ 
    .... 
    /* retireve the position of the ip header */ 
    ih = (ip_header *) (pkt_data + 
        14); //length of ethernet header 
    .... 

什么是 const的结构pcap_pkthdr *标题为（的定义），我们什么时候需要它，它是如何填充（因为在包本身如下）？没有这样的信息

What's const struct pcap_pkthdr *header for(definition), when do we need it, how is it populated (since there is no such info in the packet itself as below)?

推荐答案

如果你会不停的评论，这本来是一点点更容易。它说：

If you would have kept the comment, it would have been a tad easier. It says:

/* Callback function invoked by libpcap for every incoming packet */

这里该说，关于无效的typedef （*）pcap_handler（u_char *用户，常量结构pcap_pkthdr * pkt_header，常量u_char * pkt_data）：

pkt_header 的标题关联
  由捕获驱动到分组。
  这不是一个协议头。

pkt_header is the header associated by the capture driver to the packet. It is NOT a protocol header.

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