exception/policy: use pkt action if no flow support

Defrag memcap and flow memcap do not support flow action for the
exception policies, as there is no flow when the exception condition is
hit. In such cases, the exception policy must be considered for the
packet only, when that makes sense, or should be ignored, in case of
`bypass`.

Bug #5940

src/util-exception-policy.c

@@ -117,6 +117,34 @@ static enum ExceptionPolicy SetIPSOption(
     return p;
 }
 
+static enum ExceptionPolicy PickPacketAction(const char *option, enum ExceptionPolicy p)
+{
+    switch (p) {
+        case EXCEPTION_POLICY_DROP_FLOW:
+            SCLogWarning(
+                    "flow actions not supported for %s, defaulting to \"drop-packet\"", option);
+            return EXCEPTION_POLICY_DROP_PACKET;
+        case EXCEPTION_POLICY_PASS_FLOW:
+            SCLogWarning(
+                    "flow actions not supported for %s, defaulting to \"pass-packet\"", option);
+            return EXCEPTION_POLICY_PASS_PACKET;
+        case EXCEPTION_POLICY_BYPASS_FLOW:
+            SCLogWarning("flow actions not supported for %s, defaulting to \"ignore\"", option);
+            return EXCEPTION_POLICY_NOT_SET;
+        /* add all cases, to make sure new cases not handle will raise
+         * errors */
+        case EXCEPTION_POLICY_DROP_PACKET:
+            break;
+        case EXCEPTION_POLICY_PASS_PACKET:
+            break;
+        case EXCEPTION_POLICY_REJECT:
+            break;
+        case EXCEPTION_POLICY_NOT_SET:
+            break;
+    }
+    return p;
+}
+
 enum ExceptionPolicy ExceptionPolicyParse(const char *option, const bool support_flow)
 {
     enum ExceptionPolicy policy = EXCEPTION_POLICY_NOT_SET;
@@ -150,11 +178,7 @@ enum ExceptionPolicy ExceptionPolicyParse(const char *option, const bool support
         }
 
         if (!support_flow) {
-            if (policy == EXCEPTION_POLICY_DROP_FLOW || policy == EXCEPTION_POLICY_PASS_FLOW ||
+            policy = PickPacketAction(option, policy);
-                    policy == EXCEPTION_POLICY_BYPASS_FLOW) {
-                SCLogWarning("flow actions not supported for %s, defaulting to \"ignore\"", option);
-                policy = EXCEPTION_POLICY_NOT_SET;
-            }
         }
 
         if (strcmp(option, "exception-policy") == 0) {