Add writeAuditRPCEvent to agent_oss (#17607)

* Add writeAuditRPCEvent to agent_oss

* fix the other diffs

* backport change log

.changelog/_5740.txt

@@ -0,0 +1,3 @@
+```release-note:feature
+api: (Enterprise only) Add `POST /v1/operator/audit-hash` endpoint to calculate the hash of the data used by the audit log hash function and salt.
+```

.changelog/_5750.txt

@@ -0,0 +1,3 @@
+```release-note:feature
+cli: (Enterprise only) Add a new `consul operator audit hash` command to retrieve and compare the hash of the data used by the audit log hash function and salt.
+```

agent/agent.go

@@ -1621,7 +1621,18 @@ func (a *Agent) RPC(ctx context.Context, method string, args interface{}, reply
 			method = e + "." + p[1]
 		}
 	}
+
+	// audit log only on consul clients
+	_, ok := a.delegate.(*consul.Client)
+	if ok {
+		a.writeAuditRPCEvent(method, "OperationStart")
+	}
+
 	a.endpointsLock.RUnlock()
+
+	defer func() {
+		a.writeAuditRPCEvent(method, "OperationComplete")
+	}()
 	return a.delegate.RPC(ctx, method, args, reply)
 }
 

agent/agent_oss.go

@@ -69,3 +69,7 @@ func (a *Agent) AgentEnterpriseMeta() *acl.EnterpriseMeta {
 func (a *Agent) registerEntCache() {}
 
 func (*Agent) fillEnterpriseProxyDataSources(*proxycfg.DataSources) {}
+
+func (a *Agent) writeAuditRPCEvent(_ string, _ string) interface{} {
+	return nil
+}

agent/config/config.go

@@ -807,8 +807,9 @@ type ConfigEntries struct {
 
 // Audit allows us to enable and define destinations for auditing
 type Audit struct {
-	Enabled *bool                `mapstructure:"enabled"`
-	Sinks   map[string]AuditSink `mapstructure:"sink"`
+	Enabled    *bool                `mapstructure:"enabled"`
+	Sinks      map[string]AuditSink `mapstructure:"sink"`
+	RPCEnabled *bool                `mapstructure:"rpc_enabled"`
 }
 
 // AuditSink can be provided multiple times to define pipelines for auditing