[ovs-dev] [PATCH v1] bridge ovs-vsctl Bridge IPFIX enable_input_sampling, enable_ouput_sampling fix unexpected values

[Sayali Naval (sanaval) via dev]

As per the Open vSwitch Manual 
(http://www.openvswitch.org/support/dist-docs/ovs-vsctl.8.txt) the Bridge IPFIX 
parameters can be passed as follows:

ovs-vsctl -- set Bridge br0 ipfix=@i \
              --  --id=@i  create  IPFIX targets=\"192.168.0.34:4739\" obs_do‐
              main_id=123       obs_point_id=456       cache_active_timeout=60
              cache_max_flows=13 \
              other_config:enable-input-sampling=false \
              other_config:enable-output-sampling=false

where the default values are:
enable_input_sampling: true
enable_output_sampling: true

But in the existing code 
https://github.com/openvswitch/ovs/blob/master/vswitchd/bridge.c#L1563-L1567, 
these 2 parameters take up unexpected values in some scenarios.

        be_opts.enable_input_sampling = !smap_get_bool(&be_cfg->other_config,
                                              "enable-input-sampling", false);

        be_opts.enable_output_sampling = !smap_get_bool(&be_cfg->other_config,
                                              "enable-output-sampling", false);

Here, the function smap_get_bool is being used with a negation.

smap_get_bool is defined as below:
(https://github.com/openvswitch/ovs/blob/master/lib/smap.c#L220-L232)

/* Gets the value associated with 'key' in 'smap' and converts it to a boolean.
 * If 'key' is not in 'smap', or its value is neither "true" nor "false",
 * returns 'def'. */
bool
smap_get_bool(const struct smap *smap, const char *key, bool def)
{
    const char *value = smap_get_def(smap, key, "");
    if (def) {
        return strcasecmp("false", value) != 0;
    } else {
        return !strcasecmp("true", value);
    }
}

This returns expected values for the default case (since the above code will 
negate “false” we get from smap_get bool function and return the value “true”) 
but unexpected values for the case where the sampling value is passed through 
the CLI.
For example, if we pass "true" for other_config:enable-input-sampling in the 
CLI, the above code will negate the “true” value we get from the smap_bool 
function and return the value “false”. Same would be the case for 
enable_output_sampling.

Signed-off-by: Sayali Naval \(sanaval\) <sana...@cisco.com>
---
[bridge-ipfix-fix 277b3baae] Fix values for enable_input_sampling & 
enable_ouput_sampling
 Date: Thu May 25 10:32:43 2023 -0700
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/vswitchd/bridge.c b/vswitchd/bridge.c
index f5dc59ad0..b972d55d0 100644
--- a/vswitchd/bridge.c
+++ b/vswitchd/bridge.c
@@ -1560,11 +1560,11 @@ bridge_configure_ipfix(struct bridge *br)
         be_opts.enable_tunnel_sampling = smap_get_bool(&be_cfg->other_config,
                                              "enable-tunnel-sampling", true);

-        be_opts.enable_input_sampling = !smap_get_bool(&be_cfg->other_config,
-                                              "enable-input-sampling", false);
+        be_opts.enable_input_sampling = smap_get_bool(&be_cfg->other_config,
+                                              "enable-input-sampling", true);

-        be_opts.enable_output_sampling = !smap_get_bool(&be_cfg->other_config,
-                                              "enable-output-sampling", false);
+        be_opts.enable_output_sampling = smap_get_bool(&be_cfg->other_config,
+                                              "enable-output-sampling", true);

         virtual_obs_id = smap_get(&be_cfg->other_config, "virtual_obs_id");
         be_opts.virtual_obs_id = nullable_xstrdup(virtual_obs_id);
--
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