/
URLRewritingPolicy.java
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/
URLRewritingPolicy.java
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/**
* Copyright (C) 2015 The Gravitee team (http://gravitee.io)
*
* Licensed 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 io.gravitee.policy.urlrewriting;
import io.gravitee.common.http.HttpHeadersValues;
import io.gravitee.gateway.api.ExecutionContext;
import io.gravitee.gateway.api.Request;
import io.gravitee.gateway.api.Response;
import io.gravitee.gateway.api.buffer.Buffer;
import io.gravitee.gateway.api.http.HttpHeaderNames;
import io.gravitee.gateway.api.http.HttpHeaders;
import io.gravitee.gateway.api.stream.BufferedReadWriteStream;
import io.gravitee.gateway.api.stream.ReadWriteStream;
import io.gravitee.gateway.api.stream.SimpleReadWriteStream;
import io.gravitee.policy.api.PolicyChain;
import io.gravitee.policy.api.annotations.OnResponse;
import io.gravitee.policy.api.annotations.OnResponseContent;
import io.gravitee.policy.urlrewriting.configuration.URLRewritingPolicyConfiguration;
import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Rewrites URL in the <code>Location</code>, <code>Content-Location</code> headers on HTTP
* redirect responses.
*
* <p>
* Similar to the [ProxyPassReverse setting in mod_proxy](http://httpd.apache.org/docs/current/mod/mod_proxy.html#proxypassreverse)
*
* @author David BRASSELY (david.brassely at graviteesource.com)
* @author GraviteeSource Team
*/
public class URLRewritingPolicy {
/**
* LOGGER
*/
private static final Logger LOGGER = LoggerFactory.getLogger(URLRewritingPolicy.class);
private static final Pattern GROUP_NAME_PATTERN = Pattern.compile("\\(\\?<([a-zA-Z][a-zA-Z0-9]*)>");
private static final String GROUP_ATTRIBUTE = "group";
private static final String GROUP_NAME_ATTRIBUTE = "groupName";
private URLRewritingPolicyConfiguration configuration;
public URLRewritingPolicy(final URLRewritingPolicyConfiguration configuration) {
this.configuration = configuration;
}
@OnResponse
public void onResponse(Request request, Response response, ExecutionContext executionContext, PolicyChain policyChain) {
if (configuration.isRewriteResponseHeaders()) {
rewriteHeaders(response.headers(), executionContext);
}
if (configuration.isRewriteResponseBody()) {
response.headers().remove(HttpHeaderNames.CONTENT_LENGTH);
response.headers().set(HttpHeaderNames.TRANSFER_ENCODING, HttpHeadersValues.TRANSFER_ENCODING_CHUNKED);
}
policyChain.doNext(request, response);
}
private void rewriteHeaders(HttpHeaders headers, ExecutionContext executionContext) {
LOGGER.debug("Rewrite HTTP response headers");
Set<String> names = new HashSet<>(headers.names());
names.forEach(headerName -> {
List<String> headerValues = headers.getAll(headerName);
headers.remove(headerName);
headerValues.forEach(headerValue -> {
String rewrittenHeaderValue = rewrite(headerValue, executionContext);
headers.add(headerName, rewrittenHeaderValue);
});
});
}
@OnResponseContent
public ReadWriteStream onResponseContent(Request request, Response response, ExecutionContext executionContext) {
if (configuration.isRewriteResponseBody()) {
return new BufferedReadWriteStream() {
private Buffer buffer;
@Override
public SimpleReadWriteStream<Buffer> write(Buffer content) {
if (buffer == null) {
buffer = Buffer.buffer();
}
buffer.appendBuffer(content);
return this;
}
@Override
public void end() {
if (buffer != null) {
super.write(Buffer.buffer(rewrite(buffer.toString(), executionContext)));
}
super.end();
}
};
}
// Nothing to apply, return null. This policy will not be added to the stream chain.
return null;
}
private String rewrite(String value, ExecutionContext executionContext) {
StringBuilder sb = new StringBuilder();
if (value != null && !value.isEmpty()) {
// Compile pattern
Pattern pattern = Pattern.compile(configuration.getFromRegex());
// Apply regex capture / replacement
Matcher matcher = pattern.matcher(value);
int start = 0;
boolean result = matcher.find();
if (result) {
do {
sb.append(value.substring(start, matcher.start()));
final String[] groups = new String[matcher.groupCount()];
for (int idx = 0; idx < matcher.groupCount(); idx++) {
groups[idx] = matcher.group(idx + 1);
}
executionContext.getTemplateEngine().getTemplateContext().setVariable(GROUP_ATTRIBUTE, groups);
// Extract capture group by name
Set<String> extractedGroupNames = getNamedGroupCandidates(pattern.pattern());
Map<String, String> groupNames = extractedGroupNames
.stream()
.collect(Collectors.toMap(groupName -> groupName, matcher::group));
executionContext.getTemplateEngine().getTemplateContext().setVariable(GROUP_NAME_ATTRIBUTE, groupNames);
// Transform according to EL engine
sb.append(executionContext.getTemplateEngine().convert(configuration.getToReplacement()));
// Prepare next iteration
start = matcher.end();
result = matcher.find();
} while (result);
sb.append(value.substring(start, value.length()));
} else {
sb.append(value);
}
}
return sb.toString();
}
private Set<String> getNamedGroupCandidates(String regex) {
Set<String> namedGroups = new TreeSet<>();
Matcher m = GROUP_NAME_PATTERN.matcher(regex);
while (m.find()) {
namedGroups.add(m.group(1));
}
return namedGroups;
}
}