/*
* Copyright 2010-2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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 com.amazonaws.auth.policy.internal;
import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import com.amazonaws.SdkClientException;
import com.amazonaws.auth.policy.Action;
import com.amazonaws.auth.policy.Condition;
import com.amazonaws.auth.policy.Policy;
import com.amazonaws.auth.policy.Principal;
import com.amazonaws.auth.policy.Resource;
import com.amazonaws.auth.policy.Statement;
import com.amazonaws.util.json.Jackson;
import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.core.JsonGenerator;
/**
* Serializes an AWS policy object to a JSON string, suitable for sending to an
* AWS service.
*/
public class JsonPolicyWriter {
/** The JSON Generator to generator a JSON string.*/
private JsonGenerator generator = null;
/** The output writer to which the JSON String is written.*/
private Writer writer;
/** Logger used to log exceptions that occurs while writing the Json policy.*/
private static final Log log = LogFactory.getLog("com.amazonaws.auth.policy");
/**
* Constructs a new instance of JSONPolicyWriter.
*/
public JsonPolicyWriter() {
writer = new StringWriter();
try {
generator = Jackson.jsonGeneratorOf(writer);
} catch (IOException ioe) {
throw new SdkClientException(
"Unable to instantiate JsonGenerator.", ioe);
}
}
/**
* Converts the specified AWS policy object to a JSON string, suitable for
* passing to an AWS service.
*
* @param policy
* The AWS policy object to convert to a JSON string.
*
* @return The JSON string representation of the specified policy object.
*
* @throws IllegalArgumentException
* If the specified policy is null or invalid and cannot be
* serialized to a JSON string.
*/
public String writePolicyToString(Policy policy) {
if(!isNotNull(policy))
throw new IllegalArgumentException("Policy cannot be null");
try {
return jsonStringOf(policy);
} catch (Exception e) {
String message = "Unable to serialize policy to JSON string: "
+ e.getMessage();
throw new IllegalArgumentException(message, e);
} finally {
try { writer.close(); } catch (Exception e) { }
}
}
/**
* Converts the given <code>Policy</code> into a JSON String.
*
* @param policy
* the policy to be converted.
* @return a JSON String of the specified policy object.
*/
private String jsonStringOf(Policy policy) throws JsonGenerationException,
IOException {
generator.writeStartObject();
writeJsonKeyValue(JsonDocumentFields.VERSION, policy.getVersion());
if (isNotNull(policy.getId()))
writeJsonKeyValue(JsonDocumentFields.POLICY_ID, policy.getId());
writeJsonArrayStart(JsonDocumentFields.STATEMENT);
for (Statement statement : policy.getStatements()) {
generator.writeStartObject();
if (isNotNull(statement.getId())) {
writeJsonKeyValue(JsonDocumentFields.STATEMENT_ID, statement.getId());
}
writeJsonKeyValue(JsonDocumentFields.STATEMENT_EFFECT, statement
.getEffect().toString());
List<Principal> principals = statement.getPrincipals();
if (isNotNull(principals) && !principals.isEmpty())
writePrincipals(principals);
List<Action> actions = statement.getActions();
if (isNotNull(actions) && !actions.isEmpty())
writeActions(actions);
List<Resource> resources = statement.getResources();
if (isNotNull(resources) && !resources.isEmpty())
writeResources(resources);
List<Condition> conditions = statement.getConditions();
if (isNotNull(conditions) && !conditions.isEmpty())
writeConditions(conditions);
generator.writeEndObject();
}
writeJsonArrayEnd();
generator.writeEndObject();
generator.flush();
return writer.toString();
}
/**
* Writes the list of conditions to the JSONGenerator.
*
* @param conditions
* the conditions to be written.
*/
private void writeConditions(List<Condition> conditions)
throws JsonGenerationException, IOException {
Map<String, ConditionsByKey> conditionsByType = groupConditionsByTypeAndKey(conditions);
writeJsonObjectStart(JsonDocumentFields.CONDITION);
ConditionsByKey conditionsByKey;
for (Map.Entry<String, ConditionsByKey> entry : conditionsByType
.entrySet()) {
conditionsByKey = conditionsByType.get(entry.getKey());
writeJsonObjectStart(entry.getKey());
for (String key : conditionsByKey.keySet()) {
writeJsonArray(key, conditionsByKey.getConditionsByKey(key));
}
writeJsonObjectEnd();
}
writeJsonObjectEnd();
}
/**
* Writes the list of <code>Resource</code>s to the JSONGenerator.
*
* @param resources
* the list of resources to be written.
*/
private void writeResources(List<Resource> resources)
throws JsonGenerationException, IOException {
List<String> resourceStrings = new ArrayList<String>();
for (Resource resource : resources) {
resourceStrings.add(resource.getId());
}
writeJsonArray(JsonDocumentFields.RESOURCE, resourceStrings);
}
/**
* Writes the list of <code>Action</code>s to the JSONGenerator.
*
* @param actions
* the list of the actions to be written.
*/
private void writeActions(List<Action> actions)
throws JsonGenerationException, IOException {
List<String> actionStrings = new ArrayList<String>();
for (Action action : actions) {
actionStrings.add(action.getActionName());
}
writeJsonArray(JsonDocumentFields.ACTION, actionStrings);
}
/**
* Writes the list of <code>Principal</code>s to the JSONGenerator.
*
* @param principals
* the list of principals to be written.
*/
private void writePrincipals(List<Principal> principals)
throws JsonGenerationException, IOException {
if (principals.size() == 1 && principals.get(0).equals(Principal.All)) {
writeJsonKeyValue(JsonDocumentFields.PRINCIPAL, Principal.All.getId());
} else {
writeJsonObjectStart(JsonDocumentFields.PRINCIPAL);
Map<String, List<String>> principalsByScheme = groupPrincipalByScheme(principals);
List<String> principalValues;
for (Map.Entry<String, List<String>> entry : principalsByScheme.entrySet()) {
principalValues = principalsByScheme.get(entry.getKey());
if (principalValues.size() == 1) {
writeJsonKeyValue(entry.getKey(), principalValues.get(0));
} else {
writeJsonArray(entry.getKey(), principalValues);
}
}
writeJsonObjectEnd();
}
}
/**
* Groups the list of <code>Principal</code>s by the Scheme.
*
* @param principals
* the list of <code>Principal</code>s
* @return a map grouped by scheme of the principal.
*/
private Map<String, List<String>> groupPrincipalByScheme(
List<Principal> principals) {
Map<String, List<String>> principalsByScheme = new LinkedHashMap<String, List<String>>();
String provider;
List<String> principalValues;
for (Principal principal : principals) {
provider = principal.getProvider();
if (!principalsByScheme.containsKey(provider)) {
principalsByScheme.put(provider, new ArrayList<String>());
}
principalValues = principalsByScheme.get(provider);
principalValues.add(principal.getId());
}
return principalsByScheme;
}
/**
* Inner class to hold condition values for each key under a condition type.
*/
static class ConditionsByKey {
private Map<String,List<String>> conditionsByKey;
public ConditionsByKey(){
conditionsByKey = new LinkedHashMap<String,List<String>>();
}
public Map<String,List<String>> getConditionsByKey() {
return conditionsByKey;
}
public void setConditionsByKey(Map<String,List<String>> conditionsByKey) {
this.conditionsByKey = conditionsByKey;
}
public boolean containsKey(String key){
return conditionsByKey.containsKey(key);
}
public List<String> getConditionsByKey(String key){
return conditionsByKey.get(key);
}
public Set<String> keySet(){
return conditionsByKey.keySet();
}
public void addValuesToKey(String key, List<String> values) {
List<String> conditionValues = getConditionsByKey(key);
if (conditionValues == null)
conditionsByKey.put(key, new ArrayList<String>(values));
else
conditionValues.addAll(values);
}
}
/**
* Groups the list of <code>Condition</code>s by the condition type and
* condition key.
*
* @param conditions
* the list of conditions to be grouped
* @return a map of conditions grouped by type and then key.
*/
private Map<String, ConditionsByKey> groupConditionsByTypeAndKey(
List<Condition> conditions) {
Map<String, ConditionsByKey> conditionsByType = new LinkedHashMap<String, ConditionsByKey>();
String type;
String key;
ConditionsByKey conditionsByKey;
for (Condition condition : conditions) {
type = condition.getType();
key = condition.getConditionKey();
if (!(conditionsByType.containsKey(type))) {
conditionsByType.put(type, new ConditionsByKey());
}
conditionsByKey = conditionsByType.get(type);
conditionsByKey.addValuesToKey(key, condition.getValues());
}
return conditionsByType;
}
/**
* Writes an array along with its values to the JSONGenerator.
*
* @param arrayName
* name of the JSON array.
* @param values
* values of the JSON array.
*/
private void writeJsonArray(String arrayName, List<String> values)
throws JsonGenerationException, IOException {
writeJsonArrayStart(arrayName);
for (String value : values)
generator.writeString(value);
writeJsonArrayEnd();
}
/**
* Writes the Start of Object String to the JSONGenerator along with Object
* Name.
*
* @param fieldName
* name of the JSON Object.
*/
private void writeJsonObjectStart(String fieldName)
throws JsonGenerationException, IOException {
generator.writeObjectFieldStart(fieldName);
}
/**
* Writes the End of Object String to the JSONGenerator.
*/
private void writeJsonObjectEnd() throws JsonGenerationException, IOException {
generator.writeEndObject();
}
/**
* Writes the Start of Array String to the JSONGenerator along with Array
* Name.
*
* @param fieldName
* name of the JSON array
*/
private void writeJsonArrayStart(String fieldName)
throws JsonGenerationException, IOException {
generator.writeArrayFieldStart(fieldName);
}
/**
* Writes the End of Array String to the JSONGenerator.
*/
private void writeJsonArrayEnd() throws JsonGenerationException, IOException {
generator.writeEndArray();
}
/**
* Writes the given field and the value to the JsonGenerator
*
* @param fieldName
* the JSON field name
* @param value
* value for the field
*/
private void writeJsonKeyValue(String fieldName, String value)
throws JsonGenerationException, IOException {
generator.writeStringField(fieldName, value);
}
/**
* Checks if the given object is not null.
*
* @param object
* the object compared to null.
* @return true if the object is not null else false
*/
private boolean isNotNull(Object object) {
return null != object;
}
}