DeforaNetworks/fwknop
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update to indicate Ethernet FCS support vs. bug

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This commit is contained in:
stubbsw
2014-08-19 06:54:18 -04:00
parent b98579ab8f
commit 19f31c3e23
1 changed files with 11 additions and 15 deletions
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server/process_packet.c
+11 -15
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@@ -38,6 +38,7 @@
#include "process_packet.h"
#include "incoming_spa.h"
#include "utils.h"
#include "log_msg.h"
void
process_packet(unsigned char *args, const struct pcap_pkthdr *packet_header,
@@ -135,32 +136,27 @@ process_packet(unsigned char *args, const struct pcap_pkthdr *packet_header,
return;
/* Workaround for libpcap returning a length that is 4 bytes longer than
* the packet on the wire. Observed on:
*
* Linux beaglebone 3.8.13-bone50 #1 SMP Tue May 13 13:24:52 UTC 2014 armv7l GNU/Linux
* ldd fwknopd
* libfko.so.2 => /usr/local/lib/libfko.so.2 (0xb6f62000)
* libpcap.so.0.8 => /usr/lib/arm-linux-gnueabihf/libpcap.so.0.8 (0xb6f20000)
* libc.so.6 => /lib/arm-linux-gnueabihf/libc.so.6 (0xb6e3b000)
* /lib/ld-linux-armhf.so.3 (0xb6f94000)
* libgcc_s.so.1 => /lib/arm-linux-gnueabihf/libgcc_s.so.1 (0xb6e17000)
/* Support for the cases where libpcap returns the Ethernet Frame Check
* Sequence (4 bytes at the end of the Ethernet frame) as part of the
* capture. libpcap returning the FCS is fairly rare. Default settings on
* the following system included an Ethernet FCS in the libpcap capture:
* BeagleBone Black rev C running 3.8.13-bone50 #1 SMP Tue May 13
* 13:24:52 UTC 2014 armv7l GNU/Linux
*
* Calculate the new pkt_end from the length in the ip header.
*/
unsigned char *pcap_bug_workaround_pkt_end =
unsigned char *pcap_with_fcs_workaround_pkt_end =
((unsigned char*)iph_p) + ntohs(iph_p->tot_len);
/* Only accept the new end if it is shorter than the original pkt_end
* provided by libpcap.
*/
if(pcap_bug_workaround_pkt_end < pkt_end) {
pkt_end = pcap_bug_workaround_pkt_end;
if(pcap_with_fcs_workaround_pkt_end < pkt_end) {
log_msg(LOG_DEBUG, "Adjusting packet end from %u to %u (likely due to Ethernet FCS being included in the capture)", pkt_end, pcap_with_fcs_workaround_pkt_end);
pkt_end = pcap_with_fcs_workaround_pkt_end;
}
/* Now, find the packet data payload (depending on IPPROTO).
*/
src_ip = iph_p->saddr;