Implement basic multiple table support.

This implements basic multiple table support in ofproto and supporting
libraries and utilities. The design is the same as the one that has been
on the Open vSwitch "wdp" branch for a long time.  There is no support for
multiple tables in the software switch implementation (ofproto-dpif), only
a set of hooks for other switch implementations to use.

To allow controllers to add flows in a particular table, Open vSwitch adds
an OpenFlow 1.0 extension called NXT_FLOW_MOD_TABLE_ID.

1 files changed, 58 insertions, 4 deletions

diff --git a/include/openflow/nicira-ext.h b/include/openflow/nicira-ext.h
index 292a98738..7df978b0c 100644
--- a/include/openflow/nicira-ext.h
+++ b/include/openflow/nicira-ext.h
@@ -108,9 +108,7 @@ enum nx_flow_mod_failed_code {
     NXFMFC_HARDWARE = 0x100,
 
     /* A nonexistent table ID was specified in the "command" field of struct
-     * ofp_flow_mod, when the nxt_flow_mod_table_id extension is enabled.
-     * (This extension is not yet implemented on this branch of Open
-     * vSwitch.) */
+     * ofp_flow_mod, when the nxt_flow_mod_table_id extension is enabled. */
     NXFMFC_BAD_TABLE_ID = 0x101
 };
 
@@ -146,8 +144,17 @@ enum nicira_type {
     NXT_ROLE_REQUEST,
     NXT_ROLE_REPLY,
 
+    /* Use the upper 8 bits of the 'command' member in struct ofp_flow_mod to
+     * designate the table to which a flow is to be added?  See the big comment
+     * on struct nxt_flow_mod_table_id for more information.
+     *
+     * A screwup caused this extension to be assigned the same value as
+     * NXT_SET_FLOW_FORMAT (see below).  The two extensions do have different
+     * lengths, so they can still be distinguished. */
+    NXT_FLOW_MOD_TABLE_ID,
+
     /* Flexible flow specification (aka NXM = Nicira Extended Match). */
-    NXT_SET_FLOW_FORMAT,        /* Set flow format. */
+    NXT_SET_FLOW_FORMAT = NXT_FLOW_MOD_TABLE_ID, /* Set flow format. */
     NXT_FLOW_MOD,               /* Analogous to OFPT_FLOW_MOD. */
     NXT_FLOW_REMOVED            /* Analogous to OFPT_FLOW_REMOVED. */
 };
@@ -180,6 +187,53 @@ struct nxt_tun_id_cookie {
 };
 OFP_ASSERT(sizeof(struct nxt_tun_id_cookie) == 24);
 
+/* This command enables or disables an Open vSwitch extension that allows a
+ * controller to specify the OpenFlow table to which a flow should be added,
+ * instead of having the switch decide which table is most appropriate as
+ * required by OpenFlow 1.0.  By default, the extension is disabled.
+ *
+ * When this feature is enabled, Open vSwitch treats struct ofp_flow_mod's
+ * 16-bit 'command' member as two separate fields.  The upper 8 bits are used
+ * as the table ID, the lower 8 bits specify the command as usual.  A table ID
+ * of 0xff is treated like a wildcarded table ID.
+ *
+ * The specific treatment of the table ID depends on the type of flow mod:
+ *
+ *    - OFPFC_ADD: Given a specific table ID, the flow is always placed in that
+ *      table.  If an identical flow already exists in that table only, then it
+ *      is replaced.  If the flow cannot be placed in the specified table,
+ *      either because the table is full or because the table cannot support
+ *      flows of the given type, the switch replies with an
+ *      OFPFMFC_ALL_TABLES_FULL error.  (A controller can distinguish these
+ *      cases by comparing the current and maximum number of entries reported
+ *      in ofp_table_stats.)
+ *
+ *      If the table ID is wildcarded, the switch picks an appropriate table
+ *      itself.  If an identical flow already exist in the selected flow table,
+ *      then it is replaced.  The choice of table might depend on the flows
+ *      that are already in the switch; for example, if one table fills up then
+ *      the switch might fall back to another one.
+ *
+ *    - OFPFC_MODIFY, OFPFC_DELETE: Given a specific table ID, only flows
+ *      within that table are matched and modified or deleted.  If the table ID
+ *      is wildcarded, flows within any table may be matched and modified or
+ *      deleted.
+ *
+ *    - OFPFC_MODIFY_STRICT, OFPFC_DELETE_STRICT: Given a specific table ID,
+ *      only a flow within that table may be matched and modified or deleted.
+ *      If the table ID is wildcarded and exactly one flow within any table
+ *      matches, then it is modified or deleted; if flows in more than one
+ *      table match, then none is modified or deleted.
+ */
+struct nxt_flow_mod_table_id {
+    struct ofp_header header;
+    uint32_t vendor;            /* NX_VENDOR_ID. */
+    uint32_t subtype;           /* NXT_FLOW_MOD_TABLE_ID. */
+    uint8_t set;                /* Nonzero to enable, zero to disable. */
+    uint8_t pad[7];
+};
+OFP_ASSERT(sizeof(struct nxt_flow_mod_table_id) == 24);
+
 /* Configures the "role" of the sending controller.  The default role is:
  *
  *    - Other (NX_ROLE_OTHER), which allows the controller access to all