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package com.sun.jersey.contribs.aws.client;
import com.sun.jersey.api.client.ClientHandlerException;
import com.sun.jersey.api.client.ClientRequest;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.filter.ClientFilter;
import com.sun.jersey.api.uri.UriComponent;
import com.sun.jersey.core.util.Base64;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import java.util.Set;
import java.util.TimeZone;
import java.util.TreeSet;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.UriBuilder;
/**
*
* The filter allows you to make AWS Product Advertising API (former AWS Commerce API) calls
* without a need to sign every single request programmatically.
* The filter will automatically check the request query and update it as needed.
* It will namely try to add the Timestamp and AWSAccessKeyId parameters if missing
* and add or replace Signature parameter with a valid signature of the request.
*
* @author Jakub.Podlesak@Sun.COM
*/
public final class AWSCommerceClientFilter extends ClientFilter {
static final SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
static final String HashAlgorithm = "HmacSHA256";
static final String TimestampName = "Timestamp";
static final String AWSAccessKeyIdName = "AWSAccessKeyId";
static final String SignatureName = "Signature";
static {
dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
}
final String awsKeyId;
final String awsSecretAccessKey;
final Mac mac;
private final class AWSQuery {
final String query;
AWSQuery(ClientRequest request) {
final MultivaluedMap<String, String> queryParams = extractQueryParams(request);
addTimestamp(queryParams);
addAccessKeyId(queryParams);
query = getQuerySortedByParamNames(queryParams);
}
private MultivaluedMap<String, String> extractQueryParams(ClientRequest request) {
return UriComponent.decodeQuery(request.getURI(), true);
}
private void addTimestamp(final MultivaluedMap<String, String> queryParams) {
if (!queryParams.containsKey(TimestampName)) {
queryParams.add(TimestampName, dateFormat.format(new Date()));
}
}
private void addAccessKeyId(final MultivaluedMap<String, String> queryParams) {
if (!queryParams.containsKey(AWSAccessKeyIdName)) {
queryParams.add(AWSAccessKeyIdName, awsKeyId);
}
}
String getQuerySortedByParamNames(final MultivaluedMap<String, String> queryParams) {
Set<String> sortedParameterNames = new TreeSet<String>(String.CASE_INSENSITIVE_ORDER);
sortedParameterNames.addAll(queryParams.keySet());
StringBuilder result = new StringBuilder();
boolean firstParam = true;
for (String key : sortedParameterNames) {
final List<String> values = queryParams.get(key);
for (String val : values) {
String nextParamKeyValuePair = String.format("%s=%s", key, encodeParam(val));
if (firstParam) {
firstParam = false;
} else {
result.append('&');
}
result.append(nextParamKeyValuePair);
}
}
return result.toString();
}
private String encodeParam(String val) {
String result = UriComponent.encode(val, UriComponent.Type.QUERY);
return result.replaceAll(":", "%3A");
}
}
/**
*
* Creates a new Amazon Product Advertising API client filter instance.
* You will need valid pair of AWS access keys (Access Key and Secret Access Key).
* The keys should be accessible from http://aws.amazon.com/security-credentials
* An exception will be thrown if you provide an invalid secret access key
* or if the needed security HASH algorithm implementation is missing at your platform.
*
* @param awsKeyId AWS Access Key
* @param awsSecretAccessKey AWS Secure Access Key
* @throws InvalidKeyException
* @throws NoSuchAlgorithmException
*/
public AWSCommerceClientFilter(String awsKeyId, String awsSecretAccessKey) throws InvalidKeyException, NoSuchAlgorithmException {
this.awsKeyId = awsKeyId;
this.awsSecretAccessKey = awsSecretAccessKey;
this.mac = Mac.getInstance(HashAlgorithm);
this.mac.init(new SecretKeySpec(awsSecretAccessKey.getBytes(), HashAlgorithm));
}
@Override
public ClientResponse handle(final ClientRequest request) throws ClientHandlerException {
return getNext().handle(getSignedRequest(request));
}
private ClientRequest getSignedRequest(final ClientRequest request) {
final AWSQuery awsQuery = new AWSQuery(request);
final String toSign = getStringToSign(request, awsQuery);
final String signature = calculateSignature(toSign);
final ClientRequest result = request.clone();
result.setURI(UriBuilder.fromUri(request.getURI()).replaceQuery(appendSignature(awsQuery.query, signature)).build());
return result;
}
private String getStringToSign(final ClientRequest request, final AWSQuery awsQueryParams) {
StringBuilder result = new StringBuilder();
result.append(request.getMethod());
result.append('\n');
result.append(request.getURI().getHost());
result.append('\n');
result.append(request.getURI().getPath());
result.append('\n');
result.append(awsQueryParams.query);
return result.toString();
}
private String calculateSignature(final String toSign) throws ClientHandlerException {
try {
return new String(Base64.encode(mac.doFinal(toSign.getBytes("UTF-8"))));
} catch (Exception ex) {
throw new ClientHandlerException(ex);
}
}
private String appendSignature(final String query, final String signature) {
final StringBuilder result = new StringBuilder(query);
result.append('&').append(SignatureName).append('=').append(UriComponent.encode(signature, UriComponent.Type.QUERY_PARAM));
return result.toString();
}
}