From a1e08cec1e362b8d4c50f88bca295558fb0806a8 Mon Sep 17 00:00:00 2001 From: guy Date: Sat, 6 Nov 2004 22:45:17 +0000 Subject: [PATCH] Move the code to generate code to check for a particular linktype in the Linux cooked header into a routine of its own. --- gencode.c | 328 ++++++++++++++++++++++++++++-------------------------- 1 file changed, 169 insertions(+), 159 deletions(-) diff --git a/gencode.c b/gencode.c index 3889ba3..5db8d83 100644 --- a/gencode.c +++ b/gencode.c @@ -21,7 +21,7 @@ */ #ifndef lint static const char rcsid[] _U_ = - "@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.210 2004-10-19 15:55:28 hannes Exp $ (LBL)"; + "@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.211 2004-11-06 22:45:17 guy Exp $ (LBL)"; #endif #ifdef HAVE_CONFIG_H @@ -165,6 +165,7 @@ static struct block *gen_uncond(int); static inline struct block *gen_true(void); static inline struct block *gen_false(void); static struct block *gen_ether_linktype(int); +static struct block *gen_linux_sll_linktype(int); static struct block *gen_linktype(int); static struct block *gen_snap(bpf_u_int32, bpf_u_int32, u_int); static struct block *gen_llc(int); @@ -1259,6 +1260,172 @@ gen_ether_linktype(proto) } } +static struct block * +gen_linux_sll_linktype(proto) + register int proto; +{ + struct block *b0, *b1; + + switch (proto) { + + case LLCSAP_IP: + b0 = gen_cmp(off_linktype, BPF_H, LINUX_SLL_P_802_2); + b1 = gen_cmp(off_linktype + 2, BPF_H, (bpf_int32) + ((LLCSAP_IP << 8) | LLCSAP_IP)); + gen_and(b0, b1); + return b1; + + case LLCSAP_ISONS: + /* + * OSI protocols always use 802.2 encapsulation. + * XXX - should we check both the DSAP and the + * LSAP, like this, or should we check just the + * DSAP? + */ + b0 = gen_cmp(off_linktype, BPF_H, LINUX_SLL_P_802_2); + b1 = gen_cmp(off_linktype + 2, BPF_H, (bpf_int32) + ((LLCSAP_ISONS << 8) | LLCSAP_ISONS)); + gen_and(b0, b1); + return b1; + + case LLCSAP_NETBEUI: + /* + * NetBEUI always uses 802.2 encapsulation. + * XXX - should we check both the DSAP and the + * LSAP, like this, or should we check just the + * DSAP? + */ + b0 = gen_cmp(off_linktype, BPF_H, LINUX_SLL_P_802_2); + b1 = gen_cmp(off_linktype + 2, BPF_H, (bpf_int32) + ((LLCSAP_NETBEUI << 8) | LLCSAP_NETBEUI)); + gen_and(b0, b1); + return b1; + + case LLCSAP_IPX: + /* + * Ethernet_II frames, which are Ethernet + * frames with a frame type of ETHERTYPE_IPX; + * + * Ethernet_802.3 frames, which have a frame + * type of LINUX_SLL_P_802_3; + * + * Ethernet_802.2 frames, which are 802.3 + * frames with an 802.2 LLC header (i.e, have + * a frame type of LINUX_SLL_P_802_2) and + * with the IPX LSAP as the DSAP in the LLC + * header; + * + * Ethernet_SNAP frames, which are 802.3 + * frames with an LLC header and a SNAP + * header and with an OUI of 0x000000 + * (encapsulated Ethernet) and a protocol + * ID of ETHERTYPE_IPX in the SNAP header. + * + * First, do the checks on LINUX_SLL_P_802_2 + * frames; generate the check for either + * Ethernet_802.2 or Ethernet_SNAP frames, and + * then put a check for LINUX_SLL_P_802_2 frames + * before it. + */ + b0 = gen_cmp(off_linktype + 2, BPF_B, + (bpf_int32)LLCSAP_IPX); + b1 = gen_snap(0x000000, ETHERTYPE_IPX, + off_linktype + 2); + gen_or(b0, b1); + b0 = gen_cmp(off_linktype, BPF_H, LINUX_SLL_P_802_2); + gen_and(b0, b1); + + /* + * Now check for 802.3 frames and OR that with + * the previous test. + */ + b0 = gen_cmp(off_linktype, BPF_H, LINUX_SLL_P_802_3); + gen_or(b0, b1); + + /* + * Now add the check for Ethernet_II frames, and + * do that before checking for the other frame + * types. + */ + b0 = gen_cmp(off_linktype, BPF_H, + (bpf_int32)ETHERTYPE_IPX); + gen_or(b0, b1); + return b1; + + case ETHERTYPE_ATALK: + case ETHERTYPE_AARP: + /* + * EtherTalk (AppleTalk protocols on Ethernet link + * layer) may use 802.2 encapsulation. + */ + + /* + * Check for 802.2 encapsulation (EtherTalk phase 2?); + * we check for the 802.2 protocol type in the + * "Ethernet type" field. + */ + b0 = gen_cmp(off_linktype, BPF_H, LINUX_SLL_P_802_2); + + /* + * 802.2-encapsulated ETHERTYPE_ATALK packets are + * SNAP packets with an organization code of + * 0x080007 (Apple, for Appletalk) and a protocol + * type of ETHERTYPE_ATALK (Appletalk). + * + * 802.2-encapsulated ETHERTYPE_AARP packets are + * SNAP packets with an organization code of + * 0x000000 (encapsulated Ethernet) and a protocol + * type of ETHERTYPE_AARP (Appletalk ARP). + */ + if (proto == ETHERTYPE_ATALK) + b1 = gen_snap(0x080007, ETHERTYPE_ATALK, + off_linktype + 2); + else /* proto == ETHERTYPE_AARP */ + b1 = gen_snap(0x000000, ETHERTYPE_AARP, + off_linktype + 2); + gen_and(b0, b1); + + /* + * Check for Ethernet encapsulation (Ethertalk + * phase 1?); we just check for the Ethernet + * protocol type. + */ + b0 = gen_cmp(off_linktype, BPF_H, (bpf_int32)proto); + + gen_or(b0, b1); + return b1; + + default: + if (proto <= ETHERMTU) { + /* + * This is an LLC SAP value, so the frames + * that match would be 802.2 frames. + * Check for the 802.2 protocol type + * in the "Ethernet type" field, and + * then check the DSAP. + */ + b0 = gen_cmp(off_linktype, BPF_H, + LINUX_SLL_P_802_2); + b1 = gen_cmp(off_linktype + 2, BPF_B, + (bpf_int32)proto); + gen_and(b0, b1); + return b1; + } else { + /* + * This is an Ethernet type, so compare + * the length/type field with it (if + * the frame is an 802.2 frame, the length + * field will be <= ETHERMTU, and, as + * "proto" is > ETHERMTU, this test + * will fail and the frame won't match, + * which is what we want). + */ + return gen_cmp(off_linktype, BPF_H, + (bpf_int32)proto); + } + } +} + static struct block * gen_linktype(proto) register int proto; @@ -1333,164 +1500,7 @@ gen_linktype(proto) } case DLT_LINUX_SLL: - switch (proto) { - - case LLCSAP_IP: - b0 = gen_cmp(off_linktype, BPF_H, LINUX_SLL_P_802_2); - b1 = gen_cmp(off_linktype + 2, BPF_H, (bpf_int32) - ((LLCSAP_IP << 8) | LLCSAP_IP)); - gen_and(b0, b1); - return b1; - - case LLCSAP_ISONS: - /* - * OSI protocols always use 802.2 encapsulation. - * XXX - should we check both the DSAP and the - * LSAP, like this, or should we check just the - * DSAP? - */ - b0 = gen_cmp(off_linktype, BPF_H, LINUX_SLL_P_802_2); - b1 = gen_cmp(off_linktype + 2, BPF_H, (bpf_int32) - ((LLCSAP_ISONS << 8) | LLCSAP_ISONS)); - gen_and(b0, b1); - return b1; - - case LLCSAP_NETBEUI: - /* - * NetBEUI always uses 802.2 encapsulation. - * XXX - should we check both the DSAP and the - * LSAP, like this, or should we check just the - * DSAP? - */ - b0 = gen_cmp(off_linktype, BPF_H, LINUX_SLL_P_802_2); - b1 = gen_cmp(off_linktype + 2, BPF_H, (bpf_int32) - ((LLCSAP_NETBEUI << 8) | LLCSAP_NETBEUI)); - gen_and(b0, b1); - return b1; - - case LLCSAP_IPX: - /* - * Ethernet_II frames, which are Ethernet - * frames with a frame type of ETHERTYPE_IPX; - * - * Ethernet_802.3 frames, which have a frame - * type of LINUX_SLL_P_802_3; - * - * Ethernet_802.2 frames, which are 802.3 - * frames with an 802.2 LLC header (i.e, have - * a frame type of LINUX_SLL_P_802_2) and - * with the IPX LSAP as the DSAP in the LLC - * header; - * - * Ethernet_SNAP frames, which are 802.3 - * frames with an LLC header and a SNAP - * header and with an OUI of 0x000000 - * (encapsulated Ethernet) and a protocol - * ID of ETHERTYPE_IPX in the SNAP header. - * - * First, do the checks on LINUX_SLL_P_802_2 - * frames; generate the check for either - * Ethernet_802.2 or Ethernet_SNAP frames, and - * then put a check for LINUX_SLL_P_802_2 frames - * before it. - */ - b0 = gen_cmp(off_linktype + 2, BPF_B, - (bpf_int32)LLCSAP_IPX); - b1 = gen_snap(0x000000, ETHERTYPE_IPX, - off_linktype + 2); - gen_or(b0, b1); - b0 = gen_cmp(off_linktype, BPF_H, LINUX_SLL_P_802_2); - gen_and(b0, b1); - - /* - * Now check for 802.3 frames and OR that with - * the previous test. - */ - b0 = gen_cmp(off_linktype, BPF_H, LINUX_SLL_P_802_3); - gen_or(b0, b1); - - /* - * Now add the check for Ethernet_II frames, and - * do that before checking for the other frame - * types. - */ - b0 = gen_cmp(off_linktype, BPF_H, - (bpf_int32)ETHERTYPE_IPX); - gen_or(b0, b1); - return b1; - - case ETHERTYPE_ATALK: - case ETHERTYPE_AARP: - /* - * EtherTalk (AppleTalk protocols on Ethernet link - * layer) may use 802.2 encapsulation. - */ - - /* - * Check for 802.2 encapsulation (EtherTalk phase 2?); - * we check for the 802.2 protocol type in the - * "Ethernet type" field. - */ - b0 = gen_cmp(off_linktype, BPF_H, LINUX_SLL_P_802_2); - - /* - * 802.2-encapsulated ETHERTYPE_ATALK packets are - * SNAP packets with an organization code of - * 0x080007 (Apple, for Appletalk) and a protocol - * type of ETHERTYPE_ATALK (Appletalk). - * - * 802.2-encapsulated ETHERTYPE_AARP packets are - * SNAP packets with an organization code of - * 0x000000 (encapsulated Ethernet) and a protocol - * type of ETHERTYPE_AARP (Appletalk ARP). - */ - if (proto == ETHERTYPE_ATALK) - b1 = gen_snap(0x080007, ETHERTYPE_ATALK, - off_linktype + 2); - else /* proto == ETHERTYPE_AARP */ - b1 = gen_snap(0x000000, ETHERTYPE_AARP, - off_linktype + 2); - gen_and(b0, b1); - - /* - * Check for Ethernet encapsulation (Ethertalk - * phase 1?); we just check for the Ethernet - * protocol type. - */ - b0 = gen_cmp(off_linktype, BPF_H, (bpf_int32)proto); - - gen_or(b0, b1); - return b1; - - default: - if (proto <= ETHERMTU) { - /* - * This is an LLC SAP value, so the frames - * that match would be 802.2 frames. - * Check for the 802.2 protocol type - * in the "Ethernet type" field, and - * then check the DSAP. - */ - b0 = gen_cmp(off_linktype, BPF_H, - LINUX_SLL_P_802_2); - b1 = gen_cmp(off_linktype + 2, BPF_B, - (bpf_int32)proto); - gen_and(b0, b1); - return b1; - } else { - /* - * This is an Ethernet type, so compare - * the length/type field with it (if - * the frame is an 802.2 frame, the length - * field will be <= ETHERMTU, and, as - * "proto" is > ETHERMTU, this test - * will fail and the frame won't match, - * which is what we want). - */ - return gen_cmp(off_linktype, BPF_H, - (bpf_int32)proto); - } - } + return gen_linux_sll_linktype(proto); /*NOTREACHED*/ break;