There will be times when we want to capture packets and not view the results immediately. The libpcap library has functions to open and save the packets to a binary file. This file has the same format as a tcpdump save file.
Prior to running this recipe, we need to follow the Adding libpcap to your project recipe explained earlier in this chapter. We also need to go through the Capturing packets recipe. We will discuss how to modify the packet capture code in order to save the captured packets to a save file.
Let's save our captured packets to a file:
We begin by defining a
pcap_dumper_tpointer and creating apcap_loop. This will be the pointer to our save file.In our packet capture code from the Capturing packets recipe of this chapter, we want to replace the
pcap_loopstatement with the following lines:pcap_dumper_t *dumpfile=pcap_dump_open(handle, "~/pcapdump.pcap"); if(dumpfile==NULL){ NSLog(@"Error opening output file"); exit...