ofproto-dpif: Expose datapath capability to ovsdb.

The patch adds support for fetching the datapath's capabilities
from the result of 'check_support()', and write the supported capability
to a new database column, called 'capabilities' under Datapath table.

To see how it works, run:
 # ovs-vsctl -- add-br br0 -- set Bridge br0 datapath_type=netdev
 # ovs-vsctl -- --id=@m create Datapath datapath_version=0 \
     'ct_zones={}' 'capabilities={}' \
     -- set Open_vSwitch . datapaths:"netdev"=@m

 # ovs-vsctl list-dp-cap netdev
 ufid=true sample_nesting=true clone=true tnl_push_pop=true \
 ct_orig_tuple=true ct_eventmask=true ct_state=true \
 ct_clear=true max_vlan_headers=1 recirc=true ct_label=true \
 max_hash_alg=1 ct_state_nat=true ct_timeout=true \
 ct_mark=true ct_orig_tuple6=true check_pkt_len=true \
 masked_set_action=true max_mpls_depth=3 trunc=true ct_zone=true

Signed-off-by: William Tu <u9012063@gmail.com>
Tested-by: Greg Rose <gvrose8192@gmail.com>
Reviewed-by: Greg Rose <gvrose8192@gmail.com>
---
v5:
    Add improved documentation from Ben and
    fix checkpatch error (tab and line 79 char)
v4:
    rebase to master
v3:
    fix 32-bit build, reported by Greg
    travis: https://travis-ci.org/williamtu/ovs-travis/builds/599276267
v2:
	rebase to master

2 files changed, 34 insertions, 0 deletions

diff --git a/utilities/ovs-vsctl.8.in b/utilities/ovs-vsctl.8.in
index 14a8aa4a4..ff97922dd 100644
--- a/utilities/ovs-vsctl.8.in
+++ b/utilities/ovs-vsctl.8.in
@@ -379,6 +379,12 @@ delete a zone that does not exist has no effect.
 .IP "\fBlist\-zone\-tp \fIdatapath\fR"
 Prints the timeout policies of all zones in \fIdatapath\fR.
 .
+.SS "Datapath Capabilities Command"
+The command query datapath capabilities.
+.
+.IP "\fBlist\-dp\-cap \fIdatapath\fR"
+Prints the datapath's capabilities.
+.
 .SS "OpenFlow Controller Connectivity"
 .
 \fBovs\-vswitchd\fR can perform all configured bridging and switching
diff --git a/utilities/ovs-vsctl.c b/utilities/ovs-vsctl.c
index 7232471e6..bd3972636 100644
--- a/utilities/ovs-vsctl.c
+++ b/utilities/ovs-vsctl.c
@@ -1363,6 +1363,31 @@ pre_get_zone(struct ctl_context *ctx)
 }
 
 static void
+pre_get_dp_cap(struct ctl_context *ctx)
+{
+    ovsdb_idl_add_column(ctx->idl, &ovsrec_open_vswitch_col_datapaths);
+    ovsdb_idl_add_column(ctx->idl, &ovsrec_datapath_col_capabilities);
+}
+
+static void
+cmd_list_dp_cap(struct ctl_context *ctx)
+{
+    struct vsctl_context *vsctl_ctx = vsctl_context_cast(ctx);
+    struct smap_node *node;
+
+    struct ovsrec_datapath *dp = find_datapath(vsctl_ctx, ctx->argv[1]);
+    if (!dp) {
+        ctl_fatal("datapath \"%s\" record not found", ctx->argv[1]);
+    }
+
+    SMAP_FOR_EACH (node, &dp->capabilities) {
+        ds_put_format(&ctx->output, "%s=%s ",node->key, node->value);
+    }
+    ds_chomp(&ctx->output, ' ');
+    ds_put_char(&ctx->output, '\n');
+}
+
+static void
 cmd_add_br(struct ctl_context *ctx)
 {
     struct vsctl_context *vsctl_ctx = vsctl_context_cast(ctx);
@@ -3112,6 +3137,9 @@ static const struct ctl_command_syntax vsctl_commands[] = {
      "--if-exists", RW},
     {"list-zone-tp", 1, 1, "", pre_get_zone, cmd_list_zone_tp, NULL, "", RO},
 
+    /* Datapath capabilities. */
+    {"list-dp-cap", 1, 1, "", pre_get_dp_cap, cmd_list_dp_cap, NULL, "", RO},
+
     {NULL, 0, 0, NULL, NULL, NULL, NULL, NULL, RO},
 };