CLOUDSTACK-9361: Centrally handle API validations

Validate API arguments based on annotations. Introduces:
- NotNullOrEmpty: for doing null and empty string checks
- PositiveNumber: number > 0 (natural number)

Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>

api/src/org/apache/cloudstack/api/ApiArgValidator.java

@@ -0,0 +1,23 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package org.apache.cloudstack.api;
+
+public enum ApiArgValidator {
+    NotNullOrEmpty, // does Strings.isNullOrEmpty check
+    PositiveNumber, // does != null and > 0 check
+}

api/src/org/apache/cloudstack/api/Parameter.java

@@ -49,4 +49,6 @@ public @interface Parameter {
     String since() default "";
 
     RoleType[] authorized() default {};
+
+    ApiArgValidator[] validations() default {};
 }

server/src/com/cloud/api/dispatch/ParamProcessWorker.java

@@ -34,6 +34,7 @@ import java.text.SimpleDateFormat;
 
 import javax.inject.Inject;
 
+import com.google.common.base.Strings;
 import org.apache.log4j.Logger;
 
 import org.apache.cloudstack.acl.ControlledEntity;
@@ -49,6 +50,7 @@ import org.apache.cloudstack.api.EntityReference;
 import org.apache.cloudstack.api.InternalIdentity;
 import org.apache.cloudstack.api.Parameter;
 import org.apache.cloudstack.api.ServerApiException;
+import org.apache.cloudstack.api.ApiArgValidator;
 import org.apache.cloudstack.api.command.admin.resource.ArchiveAlertsCmd;
 import org.apache.cloudstack.api.command.admin.resource.DeleteAlertsCmd;
 import org.apache.cloudstack.api.command.admin.usage.GetUsageRecordsCmd;
@@ -92,6 +94,55 @@ public class ParamProcessWorker implements DispatchWorker {
         processParameters(task.getCmd(), task.getParams());
     }
 
+    private void validateNonEmptyString(final Object param, final String argName) {
+        if (param == null || Strings.isNullOrEmpty(param.toString())) {
+            throw new ServerApiException(ApiErrorCode.PARAM_ERROR, String.format("Empty or null value provided for API arg: %s", argName));
+        }
+    }
+
+    private void validateNaturalNumber(final Object param, final String argName) {
+        Long value = null;
+        if (param != null && param instanceof Long) {
+            value = (Long) param;
+        } else if (param != null) {
+            value = Long.valueOf(param.toString());
+        }
+        if (value == null || value < 1L) {
+            throw new ServerApiException(ApiErrorCode.PARAM_ERROR, String.format("Invalid value provided for API arg: %s", argName));
+        }
+    }
+
+    private void validateField(final Object paramObj, final Parameter annotation) throws ServerApiException {
+        if (annotation == null) {
+            return;
+        }
+        final String argName = annotation.name();
+        for (final ApiArgValidator validator : annotation.validations()) {
+            if (validator == null) {
+                continue;
+            }
+            switch (validator) {
+                case NotNullOrEmpty:
+                    switch (annotation.type()) {
+                        case UUID:
+                        case STRING:
+                            validateNonEmptyString(paramObj, argName);
+                            break;
+                    }
+                    break;
+                case PositiveNumber:
+                    switch (annotation.type()) {
+                        case SHORT:
+                        case INTEGER:
+                        case LONG:
+                            validateNaturalNumber(paramObj, argName);
+                            break;
+                    }
+                    break;
+            }
+        }
+    }
+
     @SuppressWarnings({"unchecked", "rawtypes"})
     public void processParameters(final BaseCmd cmd, final Map params) {
         final Map<Object, AccessType> entitiesToAccess = new HashMap<Object, AccessType>();
@@ -112,6 +163,7 @@ public class ParamProcessWorker implements DispatchWorker {
 
             // marshall the parameter into the correct type and set the field value
             try {
+                validateField(paramObj, parameterAnnotation);
                 setFieldValue(field, cmd, paramObj, parameterAnnotation);
             } catch (final IllegalArgumentException argEx) {
                 if (s_logger.isDebugEnabled()) {
@@ -420,6 +472,7 @@ public class ParamProcessWorker implements DispatchWorker {
                 for (final Class<?> entity : entities) {
                     CallContext.current().putContextParameter(entity, internalId);
                 }
+                validateNaturalNumber(internalId, annotation.name());
                 return internalId;
             }
         }
@@ -452,6 +505,7 @@ public class ParamProcessWorker implements DispatchWorker {
             throw new InvalidParameterValueException("Invalid parameter " + annotation.name() + " value=" + uuid +
                     " due to incorrect long value format, or entity does not exist or due to incorrect parameter annotation for the field in api cmd class.");
         }
+        validateNaturalNumber(internalId, annotation.name());
         return internalId;
     }
 }