- * XXX - should we generate the same code both
- * for tests for LLCSAP_IPX and for ETHERTYPE_IPX?
- */
-
- /*
- * This generates code to check both for the
- * IPX LSAP (Ethernet_802.2) and for Ethernet_802.3.
- */
- b0 = gen_cmp(off_linktype + 2, BPF_B,
- (bpf_int32)LLCSAP_IPX);
- b1 = gen_cmp(off_linktype + 2, BPF_H,
- (bpf_int32)0xFFFF);
- gen_or(b0, b1);
-
- /*
- * Now we add code to check for SNAP frames with
- * ETHERTYPE_IPX, i.e. Ethernet_SNAP.
- */
- b0 = gen_snap(0x000000, ETHERTYPE_IPX, 14);
- gen_or(b0, b1);
-
- /*
- * Now we generate code to check for 802.3
- * frames in general.
- */
- b0 = gen_cmp_gt(off_linktype, BPF_H, ETHERMTU);
- gen_not(b0);
-
- /*
- * Now add the check for 802.3 frames before the
- * check for Ethernet_802.2 and Ethernet_802.3,
- * as those checks should only be done on 802.3
- * frames, not on Ethernet frames.
- */
- gen_and(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 an Ethernet type field less than
- * 1500, which means it's an 802.3 length field.
- */
- b0 = gen_cmp_gt(off_linktype, BPF_H, ETHERMTU);
- gen_not(b0);
-
- /*
- * 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, 14);
- else /* proto == ETHERTYPE_AARP */
- b1 = gen_snap(0x000000, ETHERTYPE_AARP, 14);
- 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 that the frame is an 802.2 frame
- * (i.e., that the length/type field is
- * a length field, <= ETHERMTU) and
- * then check the DSAP.
- */
- b0 = gen_cmp_gt(off_linktype, BPF_H, ETHERMTU);
- gen_not(b0);
- 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);
- }
- }
- break;
-
- case DLT_IEEE802_11:
- case DLT_FDDI:
- case DLT_IEEE802:
- case DLT_ATM_RFC1483:
- case DLT_ATM_CLIP:
- /*
- * XXX - handle token-ring variable-length header.
- */
- switch (proto) {
-
- case LLCSAP_ISONS:
- return gen_cmp(off_linktype, BPF_H, (long)
- ((LLCSAP_ISONS << 8) | LLCSAP_ISONS));
-
- case LLCSAP_NETBEUI:
- return gen_cmp(off_linktype, BPF_H, (long)
- ((LLCSAP_NETBEUI << 8) | LLCSAP_NETBEUI));
-
- case LLCSAP_IPX:
- /*
- * XXX - are there ever SNAP frames for IPX on
- * non-Ethernet 802.x networks?
- */
- return gen_cmp(off_linktype, BPF_B,
- (bpf_int32)LLCSAP_IPX);
-
- case ETHERTYPE_ATALK:
- /*
- * 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).
- *
- * XXX - check for an organization code of
- * encapsulated Ethernet as well?
- */
- return gen_snap(0x080007, ETHERTYPE_ATALK,
- off_linktype);
- break;
-
- default:
- /*
- * XXX - we don't have to check for IPX 802.3
- * here, but should we check for the IPX Ethertype?
- */
- if (proto <= ETHERMTU) {
- /*
- * This is an LLC SAP value, so check
- * the DSAP.
- */
- return gen_cmp(off_linktype, BPF_B,
- (bpf_int32)proto);
- } else {
- /*
- * This is an Ethernet type; we assume
- * that it's unlikely that it'll
- * appear in the right place at random,
- * and therefore check only the
- * location that would hold the Ethernet
- * type in a SNAP frame with an organization
- * code of 0x000000 (encapsulated Ethernet).
- *
- * XXX - if we were to check for the SNAP DSAP
- * and LSAP, as per XXX, and were also to check
- * for an organization code of 0x000000
- * (encapsulated Ethernet), we'd do
- *
- * return gen_snap(0x000000, proto,
- * off_linktype);
- *
- * here; for now, we don't, as per the above.
- * I don't know whether it's worth the
- * extra CPU time to do the right check
- * or not.
- */
- return gen_cmp(off_linktype+6, BPF_H,
- (bpf_int32)proto);
- }
- }
- break;
-
- case DLT_LINUX_SLL:
- switch (proto) {
-
- 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.
projects / libpcap / blobdiff