Add some more OR_ values, to make it clearer what we're doing.

Distinguish between "offset from the beginning of the 802.2 LLC header",
"offset from the beginning of the MPLS payload", and "offset from the
beginning of the link-layer payload".

diff --git a/gencode.c b/gencode.c
index b76c9f33c0734519d8326d2ef158075fa0add86b..c9cf7ceb7e4ba7c91c6821630926953392c94189 100644 (file)
--- a/gencode.c
+++ b/gencode.c
@@ -169,7 +169,9 @@ static struct block *root;
 enum e_offrel {
        OR_PACKET,      /* full packet data */
        OR_LINK,        /* link-layer header */
+       OR_LLC,         /* 802.2 LLC header */
        OR_LINKPL,      /* link-layer payload */
+       OR_MPLSPL,      /* MPLS payload */
        OR_NET,         /* network-layer header */
        OR_NET_NOSNAP,  /* network-layer header, with no SNAP header at the link layer */
        OR_TRAN_IPV4,   /* transport-layer header, with IPv4 network layer */
@@ -1583,7 +1585,9 @@ gen_load_a(offrel, offset, size)
                s = gen_load_llrel(offset, size);
                break;
 
+       case OR_LLC:
        case OR_LINKPL:
+       case OR_MPLSPL:
                s = gen_load_linkplrel(offset, size);
                break;
 
@@ -1759,7 +1763,7 @@ gen_ether_linktype(proto)
                 */
                b0 = gen_cmp_gt(OR_LINK, off_linktype, BPF_H, ETHERMTU);
                gen_not(b0);
-               b1 = gen_cmp(OR_LINKPL, 0, BPF_H, (bpf_int32)
+               b1 = gen_cmp(OR_LLC, 0, BPF_H, (bpf_int32)
                             ((proto << 8) | proto));
                gen_and(b0, b1);
                return b1;
@@ -1797,8 +1801,8 @@ gen_ether_linktype(proto)
                 * This generates code to check both for the
                 * IPX LSAP (Ethernet_802.2) and for Ethernet_802.3.
                 */
-               b0 = gen_cmp(OR_LINKPL, 0, BPF_B, (bpf_int32)LLCSAP_IPX);
-               b1 = gen_cmp(OR_LINKPL, 0, BPF_H, (bpf_int32)0xFFFF);
+               b0 = gen_cmp(OR_LLC, 0, BPF_B, (bpf_int32)LLCSAP_IPX);
+               b1 = gen_cmp(OR_LLC, 0, BPF_H, (bpf_int32)0xFFFF);
                gen_or(b0, b1);
 
                /*
@@ -1966,7 +1970,7 @@ gen_linux_sll_linktype(proto)
                 * (i.e., other SAP values)?
                 */
                b0 = gen_cmp(OR_LINK, off_linktype, BPF_H, LINUX_SLL_P_802_2);
-               b1 = gen_cmp(OR_LINKPL, 0, BPF_H, (bpf_int32)
+               b1 = gen_cmp(OR_LLC, 0, BPF_H, (bpf_int32)
                             ((proto << 8) | proto));
                gen_and(b0, b1);
                return b1;
@@ -1997,7 +2001,7 @@ gen_linux_sll_linktype(proto)
                 * then put a check for LINUX_SLL_P_802_2 frames
                 * before it.
                 */
-               b0 = gen_cmp(OR_LINKPL, 0, BPF_B, (bpf_int32)LLCSAP_IPX);
+               b0 = gen_cmp(OR_LLC, 0, BPF_B, (bpf_int32)LLCSAP_IPX);
                b1 = gen_snap(0x000000, ETHERTYPE_IPX);
                gen_or(b0, b1);
                b0 = gen_cmp(OR_LINK, off_linktype, BPF_H, LINUX_SLL_P_802_2);
@@ -3475,7 +3479,7 @@ gen_snap(orgcode, ptype)
        snapblock[5] = (orgcode >> 0);  /* lower 8 bits of organization code */
        snapblock[6] = (ptype >> 8);    /* upper 8 bits of protocol type */
        snapblock[7] = (ptype >> 0);    /* lower 8 bits of protocol type */
-       return gen_bcmp(OR_LINKPL, 0, 8, snapblock);
+       return gen_bcmp(OR_LLC, 0, 8, snapblock);
 }
 
 /*
@@ -3500,7 +3504,7 @@ gen_llc(void)
                 * Now check for the purported DSAP and SSAP not being
                 * 0xFF, to rule out NetWare-over-802.3.
                 */
-               b1 = gen_cmp(OR_LINKPL, 0, BPF_H, (bpf_int32)0xFFFF);
+               b1 = gen_cmp(OR_LLC, 0, BPF_H, (bpf_int32)0xFFFF);
                gen_not(b1);
                gen_and(b0, b1);
                return b1;
@@ -3567,7 +3571,7 @@ gen_llc_i(void)
         * Load the control byte and test the low-order bit; it must
         * be clear for I frames.
         */
-       s = gen_load_a(OR_LINKPL, 2, BPF_B);
+       s = gen_load_a(OR_LLC, 2, BPF_B);
        b1 = new_block(JMP(BPF_JSET));
        b1->s.k = 0x01;
        b1->stmts = s;
@@ -3590,7 +3594,7 @@ gen_llc_s(void)
         * Now compare the low-order 2 bit of the control byte against
         * the appropriate value for S frames.
         */
-       b1 = gen_mcmp(OR_LINKPL, 2, BPF_B, LLC_S_FMT, 0x03);
+       b1 = gen_mcmp(OR_LLC, 2, BPF_B, LLC_S_FMT, 0x03);
        gen_and(b0, b1);
        return b1;
 }
@@ -3609,7 +3613,7 @@ gen_llc_u(void)
         * Now compare the low-order 2 bit of the control byte against
         * the appropriate value for U frames.
         */
-       b1 = gen_mcmp(OR_LINKPL, 2, BPF_B, LLC_U_FMT, 0x03);
+       b1 = gen_mcmp(OR_LLC, 2, BPF_B, LLC_U_FMT, 0x03);
        gen_and(b0, b1);
        return b1;
 }
@@ -3627,7 +3631,7 @@ gen_llc_s_subtype(bpf_u_int32 subtype)
        /*
         * Now check for an S frame with the appropriate type.
         */
-       b1 = gen_mcmp(OR_LINKPL, 2, BPF_B, subtype, LLC_S_CMD_MASK);
+       b1 = gen_mcmp(OR_LLC, 2, BPF_B, subtype, LLC_S_CMD_MASK);
        gen_and(b0, b1);
        return b1;
 }
@@ -3645,7 +3649,7 @@ gen_llc_u_subtype(bpf_u_int32 subtype)
        /*
         * Now check for a U frame with the appropriate type.
         */
-       b1 = gen_mcmp(OR_LINKPL, 2, BPF_B, subtype, LLC_U_CMD_MASK);
+       b1 = gen_mcmp(OR_LLC, 2, BPF_B, subtype, LLC_U_CMD_MASK);
        gen_and(b0, b1);
        return b1;
 }
@@ -3677,10 +3681,9 @@ gen_llc_linktype(proto)
                /*
                 * XXX - should we check both the DSAP and the
                 * SSAP, like this, or should we check just the
-                * DSAP, as we do for other types <= ETHERMTU
-                * (i.e., other SAP values)?
+                * DSAP, as we do for other SAP values?
                 */
-               return gen_cmp(OR_LINKPL, 0, BPF_H, (bpf_u_int32)
+               return gen_cmp(OR_LLC, 0, BPF_H, (bpf_u_int32)
                             ((proto << 8) | proto));
 
        case LLCSAP_IPX:
@@ -3688,7 +3691,7 @@ gen_llc_linktype(proto)
                 * XXX - are there ever SNAP frames for IPX on
                 * non-Ethernet 802.x networks?
                 */
-               return gen_cmp(OR_LINKPL, 0, BPF_B,
+               return gen_cmp(OR_LLC, 0, BPF_B,
                    (bpf_int32)LLCSAP_IPX);
 
        case ETHERTYPE_ATALK:
@@ -3713,7 +3716,7 @@ gen_llc_linktype(proto)
                         * This is an LLC SAP value, so check
                         * the DSAP.
                         */
-                       return gen_cmp(OR_LINKPL, 0, BPF_B, (bpf_int32)proto);
+                       return gen_cmp(OR_LLC, 0, BPF_B, (bpf_int32)proto);
                } else {
                        /*
                         * This is an Ethernet type; we assume that it's
@@ -3734,7 +3737,7 @@ gen_llc_linktype(proto)
                         * I don't know whether it's worth the extra CPU
                         * time to do the right check or not.
                         */
-                       return gen_cmp(OR_LINKPL, 6, BPF_H, (bpf_int32)proto);
+                       return gen_cmp(OR_LLC, 6, BPF_H, (bpf_int32)proto);
                }
        }
 }
@@ -8190,7 +8193,7 @@ gen_mpls(label_num)
 
         if (label_stack_depth > 0) {
             /* just match the bottom-of-stack bit clear */
-            b0 = gen_mcmp(OR_LINKPL, off_nl-2, BPF_B, 0, 0x01);
+            b0 = gen_mcmp(OR_MPLSPL, off_nl-2, BPF_B, 0, 0x01);
         } else {
             /*
              * We're not in an MPLS stack yet, so check the link-layer
@@ -8225,7 +8228,7 @@ gen_mpls(label_num)
        /* If a specific MPLS label is requested, check it */
        if (label_num >= 0) {
                label_num = label_num << 12; /* label is shifted 12 bits on the wire */
-               b1 = gen_mcmp(OR_LINKPL, off_nl, BPF_W, (bpf_int32)label_num,
+               b1 = gen_mcmp(OR_MPLSPL, off_nl, BPF_W, (bpf_int32)label_num,
                    0xfffff000); /* only compare the first 20 bits */
                gen_and(b0, b1);
                b0 = b1;