Use gen_cmp_le() directly where it fits.

The opposite of "greater than" is "less or equal".  Update two comments
to spell the edge case right (it is either > ETHERMTU or <= ETHERMTU).
This generates exactly the same filter program, hence there is no change
to the tests.

diff --git a/gencode.c b/gencode.c
index 050e7931aa2e992dfbef7bfd39f27093de9399e6..a9e431649edf2d1df44905d8c2f55c1adc4eea72 100644 (file)
--- a/gencode.c
+++ b/gencode.c
@@ -2134,8 +2134,7 @@ gen_ether_linktype(compiler_state_t *cstate, bpf_u_int32 ll_proto)
                 * DSAP, as we do for other types <= ETHERMTU
                 * (i.e., other SAP values)?
                 */
-               b0 = gen_cmp_gt(cstate, OR_LINKTYPE, 0, BPF_H, ETHERMTU);
-               gen_not(b0);
+               b0 = gen_cmp_le(cstate, OR_LINKTYPE, 0, BPF_H, ETHERMTU);
                b1 = gen_cmp(cstate, OR_LLC, 0, BPF_H, (ll_proto << 8) | ll_proto);
                gen_and(b0, b1);
                return b1;
@@ -2188,8 +2187,7 @@ gen_ether_linktype(compiler_state_t *cstate, bpf_u_int32 ll_proto)
                 * Now we generate code to check for 802.3
                 * frames in general.
                 */
-               b0 = gen_cmp_gt(cstate, OR_LINKTYPE, 0, BPF_H, ETHERMTU);
-               gen_not(b0);
+               b0 = gen_cmp_le(cstate, OR_LINKTYPE, 0, BPF_H, ETHERMTU);
 
                /*
                 * Now add the check for 802.3 frames before the
@@ -2217,11 +2215,10 @@ gen_ether_linktype(compiler_state_t *cstate, bpf_u_int32 ll_proto)
 
                /*
                 * Check for 802.2 encapsulation (EtherTalk phase 2?);
-                * we check for an Ethernet type field less than
+                * we check for an Ethernet type field less or equal than
                 * 1500, which means it's an 802.3 length field.
                 */
-               b0 = gen_cmp_gt(cstate, OR_LINKTYPE, 0, BPF_H, ETHERMTU);
-               gen_not(b0);
+               b0 = gen_cmp_le(cstate, OR_LINKTYPE, 0, BPF_H, ETHERMTU);
 
                /*
                 * 802.2-encapsulated ETHERTYPE_ATALK packets are
@@ -2260,8 +2257,7 @@ gen_ether_linktype(compiler_state_t *cstate, bpf_u_int32 ll_proto)
                         * a length field, <= ETHERMTU) and
                         * then check the DSAP.
                         */
-                       b0 = gen_cmp_gt(cstate, OR_LINKTYPE, 0, BPF_H, ETHERMTU);
-                       gen_not(b0);
+                       b0 = gen_cmp_le(cstate, OR_LINKTYPE, 0, BPF_H, ETHERMTU);
                        b1 = gen_cmp(cstate, OR_LINKTYPE, 2, BPF_B, ll_proto);
                        gen_and(b0, b1);
                        return b1;
@@ -3877,11 +3873,10 @@ gen_llc_internal(compiler_state_t *cstate)
 
        case DLT_EN10MB:
                /*
-                * We check for an Ethernet type field less than
+                * We check for an Ethernet type field less or equal than
                 * 1500, which means it's an 802.3 length field.
                 */
-               b0 = gen_cmp_gt(cstate, OR_LINKTYPE, 0, BPF_H, ETHERMTU);
-               gen_not(b0);
+               b0 = gen_cmp_le(cstate, OR_LINKTYPE, 0, BPF_H, ETHERMTU);
 
                /*
                 * Now check for the purported DSAP and SSAP not being