From: Roy Marples <roy@marples.name>
Date: Tue, 15 Dec 2015 14:30:39 +0000 (+0000)
Subject: Optimise the ARP BPF filter, thanks to Nate Karstens.
X-Git-Tag: v6.10.0~46
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0e15ea5a1a1ed8a592721c1cc43753ffcd3f893a;p=thirdparty%2Fdhcpcd.git

Optimise the ARP BPF filter, thanks to Nate Karstens.
---

diff --git a/bpf-filter.h b/bpf-filter.h
index 08df683c..de9b277e 100644
--- a/bpf-filter.h
+++ b/bpf-filter.h
@@ -34,13 +34,12 @@ static const struct bpf_insn arp_bpf_filter [] = {
 #ifndef BPF_SKIPTYPE
 	/* Make sure this is an ARP packet... */
 	BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12),
-	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_ARP, 0, 3),
+	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_ARP, 0, 4),
 #endif
 	/* Make sure this is an ARP REQUEST... */
 	BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20 + BPF_ETHCOOK),
-	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REQUEST, 2, 0),
+	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REQUEST, 1, 0),
 	/* or ARP REPLY... */
-	BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20 + BPF_ETHCOOK),
 	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REPLY, 0, 1),
 	/* If we passed all the tests, ask for the whole packet. */
 	BPF_STMT(BPF_RET + BPF_K, BPF_WHOLEPACKET),