Orchagent validates mirror session queue parameter against maximum va…

…lue from SAI (sonic-net#1957)

* Orchagent validates mirror session queue parameter against maximum value from SAI
Signed-off-by: Raphael Tryster <raphaelt@nvidia.com>

orchagent/mirrororch.cpp

@@ -39,6 +39,11 @@
 #define MIRROR_SESSION_DSCP_MIN         0
 #define MIRROR_SESSION_DSCP_MAX         63
 
+// 15 is a typical value, but if vendor's SAI does not supply the maximum value,
+// allow all 8-bit numbers, effectively cancelling validation by orchagent.
+#define MIRROR_SESSION_DEFAULT_NUM_TC   255
+
+extern sai_switch_api_t *sai_switch_api;
 extern sai_mirror_api_t *sai_mirror_api;
 extern sai_port_api_t *sai_port_api;
 
@@ -80,9 +85,26 @@ MirrorOrch::MirrorOrch(TableConnector stateDbConnector, TableConnector confDbCon
         m_policerOrch(policerOrch),
         m_mirrorTable(stateDbConnector.first, stateDbConnector.second)
 {
+    sai_status_t status;
+    sai_attribute_t attr;
+
     m_portsOrch->attach(this);
     m_neighOrch->attach(this);
     m_fdbOrch->attach(this);
+
+    // Retrieve the number of valid values for queue, starting at 0
+    attr.id = SAI_SWITCH_ATTR_QOS_MAX_NUMBER_OF_TRAFFIC_CLASSES;
+    status = sai_switch_api->get_switch_attribute(gSwitchId, 1, &attr);
+    if (status != SAI_STATUS_SUCCESS)
+    {
+        SWSS_LOG_WARN("Failed to get switch attribute number of traffic classes. \
+                       Use default value. rv:%d", status);
+        m_maxNumTC = MIRROR_SESSION_DEFAULT_NUM_TC;
+    }
+    else
+    {
+        m_maxNumTC = attr.value.u8;
+    }
 }
 
 bool MirrorOrch::bake()
@@ -373,6 +395,11 @@ task_process_status MirrorOrch::createEntry(const string& key, const vector<Fiel
             else if (fvField(i) == MIRROR_SESSION_QUEUE)
             {
                 entry.queue = to_uint<uint8_t>(fvValue(i));
+                if (entry.queue >= m_maxNumTC)
+                {
+                    SWSS_LOG_ERROR("Failed to get valid queue %s", fvValue(i).c_str());
+                    return task_process_status::task_invalid_entry;
+                }
             }
             else if (fvField(i) == MIRROR_SESSION_POLICER)
             {

orchagent/mirrororch.h

@@ -95,6 +95,8 @@ class MirrorOrch : public Orch, public Observer, public Subject
     NeighOrch *m_neighOrch;
     FdbOrch *m_fdbOrch;
     PolicerOrch *m_policerOrch;
+    // Maximum number of traffic classes starting at 0, thus queue can be 0 - m_maxNumTC-1
+    uint8_t m_maxNumTC;
 
     Table m_mirrorTable;
 

tests/test_mirror_port_span.py

@@ -7,6 +7,54 @@
 @pytest.mark.usefixtures('dvs_mirror_manager')
 @pytest.mark.usefixtures('dvs_policer_manager')
 class TestMirror(object):
+
+    def check_syslog(self, dvs, marker, log, expected_cnt):
+        (ec, out) = dvs.runcmd(['sh', '-c', "awk \'/%s/,ENDFILE {print;}\' /var/log/syslog | grep \'%s\' | wc -l" % (marker, log)])
+        assert out.strip() == str(expected_cnt)
+
+
+    def test_PortMirrorQueue(self, dvs, testlog):
+        """
+        This test covers valid and invalid values of the queue parameter.  All sessions have source & dest port.
+        Operation flow:
+        1. Create mirror session with queue 0, verify session becomes active and error not written to log.
+        2. Create mirror session with queue max valid value, verify session becomes active and error not written to log.
+        3. Create mirror session with queue max valid value + 1, verify session doesnt get created and error written to log.
+        Due to lag in table operations, verify_no_mirror is necessary at the end of each step, to ensure cleanup before next step.
+        Note that since orchagent caches max valid value during initialization, this test cannot simulate a value from SAI, e.g.
+        by calling setReadOnlyAttr, because orchagent has already completed initialization and would never read the simulated value.
+        Therefore, the default value must be used, MIRROR_SESSION_DEFAULT_NUM_TC which is defined in mirrororch.cpp as 255.
+        """
+
+        session = "TEST_SESSION"
+        dst_port = "Ethernet16"
+        src_ports = "Ethernet12"
+
+        # Sub Test 1
+        marker = dvs.add_log_marker()
+        self.dvs_mirror.create_span_session(session, dst_port, src_ports, direction="BOTH", queue="0")
+        self.dvs_mirror.verify_session_status(session)
+        self.dvs_mirror.remove_mirror_session(session)
+        self.dvs_mirror.verify_no_mirror()
+        self.check_syslog(dvs, marker, "Failed to get valid queue 0", 0)
+
+        # Sub Test 2
+        marker = dvs.add_log_marker()
+        self.dvs_mirror.create_span_session(session, dst_port, src_ports, direction="RX", queue="254")
+        self.dvs_mirror.verify_session_status(session)
+        self.dvs_mirror.remove_mirror_session(session)
+        self.dvs_mirror.verify_no_mirror()
+        self.check_syslog(dvs, marker, "Failed to get valid queue 254", 0)
+
+        # Sub Test 3
+        marker = dvs.add_log_marker()
+        self.dvs_mirror.create_span_session(session, dst_port, src_ports, direction="TX", queue="255")
+        self.dvs_mirror.verify_session_status(session, expected=0)
+        self.dvs_mirror.remove_mirror_session(session)
+        self.dvs_mirror.verify_no_mirror()
+        self.check_syslog(dvs, marker, "Failed to get valid queue 255", 1)
+
+
     def test_PortMirrorAddRemove(self, dvs, testlog):
         """
         This test covers the basic SPAN mirror session creation and removal operations
@@ -471,7 +519,6 @@ def test_PortLAGMirrorUpdateLAG(self, dvs, testlog):
         self.dvs_vlan.asic_db.wait_for_n_keys("ASIC_STATE:SAI_OBJECT_TYPE_LAG", 0)
 
 
-
 # Add Dummy always-pass test at end as workaroud
 # for issue when Flaky fail on final test it invokes module tear-down before retrying
 def test_nonflaky_dummy():