nx-match: Fix comments.

[sliver-openvswitch.git] / lib / nx-match.c

diff --git a/lib/nx-match.c b/lib/nx-match.c
index 3bb71e2..11cbff3 100644 (file)
--- a/lib/nx-match.c
+++ b/lib/nx-match.c
@@ -183,7 +183,7 @@ nx_pull_raw(const uint8_t *p, unsigned int match_len, bool strict,
                 if (NXM_HASMASK(header)) {
                     memcpy(cookie_mask, p + 4 + width, width);
                 } else {
-                    *cookie_mask = htonll(UINT64_MAX);
+                    *cookie_mask = OVS_BE64_MAX;
                 }
                 error = 0;
             }
@@ -280,8 +280,8 @@ oxm_pull_match__(struct ofpbuf *b, bool strict, struct match *match)
                        strict, match, NULL, NULL);
 }
 
-/* Parses the oxm formatted match description preceded by a struct ofp11_match
- * in 'b' with length 'match_len'.  Stores the result in 'match'.
+/* Parses the oxm formatted match description preceded by a struct
+ * ofp11_match_header in 'b'.  Stores the result in 'match'.
  *
  * Fails with an error when encountering unknown OXM headers.
  *
@@ -293,7 +293,7 @@ oxm_pull_match(struct ofpbuf *b, struct match *match)
 }
 
 /* Behaves the same as oxm_pull_match() with one exception.  Skips over unknown
- * PXM headers instead of failing with an error when they are encountered. */
+ * OXM headers instead of failing with an error when they are encountered. */
 enum ofperr
 oxm_pull_match_loose(struct ofpbuf *b, struct match *match)
 {
@@ -361,7 +361,7 @@ nxm_put_16m(struct ofpbuf *b, uint32_t header, ovs_be16 value, ovs_be16 mask)
     case 0:
         break;
 
-    case CONSTANT_HTONS(UINT16_MAX):
+    case OVS_BE16_MAX:
         nxm_put_16(b, header, value);
         break;
 
@@ -393,7 +393,7 @@ nxm_put_32m(struct ofpbuf *b, uint32_t header, ovs_be32 value, ovs_be32 mask)
     case 0:
         break;
 
-    case CONSTANT_HTONL(UINT32_MAX):
+    case OVS_BE32_MAX:
         nxm_put_32(b, header, value);
         break;
 
@@ -425,7 +425,7 @@ nxm_put_64m(struct ofpbuf *b, uint32_t header, ovs_be64 value, ovs_be64 mask)
     case 0:
         break;
 
-    case CONSTANT_HTONLL(UINT64_MAX):
+    case OVS_BE64_MAX:
         nxm_put_64(b, header, value);
         break;
 
@@ -570,7 +570,7 @@ nx_put_raw(struct ofpbuf *b, bool oxm, const struct match *match,
     int match_len;
     int i;
 
-    BUILD_ASSERT_DECL(FLOW_WC_SEQ == 20);
+    BUILD_ASSERT_DECL(FLOW_WC_SEQ == 21);
 
     /* Metadata. */
     if (match->wc.masks.in_port.ofp_port) {
@@ -1308,13 +1308,11 @@ void
 nxm_execute_reg_move(const struct ofpact_reg_move *move,
                      struct flow *flow, struct flow_wildcards *wc)
 {
-    union mf_subvalue mask_value;
     union mf_value src_value;
     union mf_value dst_value;
 
-    memset(&mask_value, 0xff, sizeof mask_value);
-    mf_write_subfield_flow(&move->dst, &mask_value, &wc->masks);
-    mf_write_subfield_flow(&move->src, &mask_value, &wc->masks);
+    mf_mask_field_and_prereqs(move->dst.field, &wc->masks);
+    mf_mask_field_and_prereqs(move->src.field, &wc->masks);
 
     mf_get_value(move->dst.field, flow, &dst_value);
     mf_get_value(move->src.field, flow, &src_value);
@@ -1325,8 +1323,33 @@ nxm_execute_reg_move(const struct ofpact_reg_move *move,
 }
 
 void
-nxm_execute_reg_load(const struct ofpact_reg_load *load, struct flow *flow)
-{
+nxm_execute_reg_load(const struct ofpact_reg_load *load, struct flow *flow,
+                     struct flow_wildcards *wc)
+{
+    /* Since at the datapath interface we do not have set actions for
+     * individual fields, but larger sets of fields for a given protocol
+     * layer, the set action will in practice only ever apply to exactly
+     * matched flows for the given protocol layer.  For example, if the
+     * reg_load changes the IP TTL, the corresponding datapath action will
+     * rewrite also the IP addresses and TOS byte.  Since these other field
+     * values may not be explicitly set, they depend on the incoming flow field
+     * values, and are hence all of them are set in the wildcards masks, when
+     * the action is committed to the datapath.  For the rare case, where the
+     * reg_load action does not actually change the value, and no other flow
+     * field values are set (or loaded), the datapath action is skipped, and
+     * no mask bits are set.  Such a datapath flow should, however, be
+     * dependent on the specific field value, so the corresponding wildcard
+     * mask bits must be set, lest the datapath flow be applied to packets
+     * containing some other value in the field and the field value remain
+     * unchanged regardless of the incoming value.
+     *
+     * We set the masks here for the whole fields, and their prerequisities.
+     * Even if only the lower byte of a TCP destination port is set,
+     * we set the mask for the whole field, and also the ip_proto in the IP
+     * header, so that the kernel flow would not be applied on, e.g., a UDP
+     * packet, or any other IP protocol in addition to TCP packets.
+     */
+    mf_mask_field_and_prereqs(load->dst.field, &wc->masks);
     mf_write_subfield_flow(&load->dst, &load->subvalue, flow);
 }