[tcpdump-workers] segfault in pcap_snapshot

[Karl Sj�dahl]

Hi. I’m tryin to write a simple sniffer with libpcap but I have some problems that I can’t be able to solve and it’s starting to get frustrating.   Code:   #define FILTER “udp or tcp” #define PROMISC 1 ... if(pcap_open_live(device, BUFSIZ, PROMISC, 0, errbuf) == -1) { ��������������������� error handling } if(pcap_lookupnet(device, &local_net, &netmask, errbuf) == -1) { ��������������������� error handling } if(pcap_compile(p, &filter_code, TESTFILTER, 0, netmask) == -1) { ��� ����������������� error handling��� } if(pcap_setfilter(p, &filter_code) == -1) { �������������� ������ error handling }   After pcap_lookupnet the program segfaults. I have tested everything with pcap_compile and I can’t understabd what is wrong.   Program received signal SIGSEGV, Segmentation fault. 0x88208ac in pcap_snapshot () (gdb)   And it says there is an error in pcap_snapshot. If i put a break on pcap_compile and step through it it looks like this:   Breakpoint 1, 0x8821d0c in pcap_compile () (gdb) ni 0x8821d10 in pcap_compile () (gdb) 0x8821d14 in pcap_compile () (gdb) 0x8821b4c in bpf_filter () (gdb) 0x8821b50 in bpf_filter () (gdb) 0x8821d18 in pcap_compile () (gdb) 0x8821d1c in pcap_compile () (gdb) 0x8821d20 in pcap_compile () (gdb) 0x8821d24 in pcap_compile () (gdb) 0x8821d28 in pcap_compile () (gdb) 0x8821d2c in pcap_compile () (gdb) 0x8821d30 in pcap_compile () (gdb) 0x8821d34 in pcap_compile () (gdb) 0x8821d38 in pcap_compile () (gdb) 0x8821d3c in pcap_compile () (gdb) 0x8821d40 in pcap_compile () (gdb) 0x8821d44 in pcap_compile () (gdb) 0x8821d48 in pcap_compile () (gdb) 0x8821d4c in pcap_compile () (gdb) 0x8821d50 in pcap_compile () (gdb) 0x8821d54 in pcap_compile () (gdb) 0x8b34170 in __DTOR_LIST__ () (gdb) 0x8b34174 in __DTOR_LIST__ () (gdb) 0x8b34128 in __DTOR_LIST__ () (gdb) 0x8b3412c in __DTOR_LIST__ () (gdb) 0x8b34130 in __DTOR_LIST__ () (gdb)   Program received signal SIGBUS, Bus error. 0x82141c4 in _dl_bind () (gdb)   Anybody that can see any errors or can point me in the right direction where to find good info on how I can write the pcap_compile because it looks like there error is made there or maybe in the creation of p.   Thanks.   // Dunceor --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.593 / Virus Database: 376 - Release Date: 2004-02-20