Simple OAuth Handler for WSO2 ESB

SimpleOauthHandler.java

package org.wso2.handler;

import org.apache.axis2.client.Options;
import org.apache.axis2.client.ServiceClient;
import org.apache.axis2.context.ConfigurationContext;
import org.apache.axis2.context.ConfigurationContextFactory;
import org.apache.axis2.transport.http.HTTPConstants;
import org.apache.axis2.transport.http.HttpTransportProperties;
import org.apache.http.HttpHeaders;
import org.apache.synapse.core.axis2.Axis2MessageContext;
import org.wso2.carbon.identity.oauth2.stub.OAuth2TokenValidationServiceStub;
import org.wso2.carbon.identity.oauth2.stub.dto.OAuth2TokenValidationRequestDTO;
import org.apache.synapse.ManagedLifecycle;
import org.apache.synapse.MessageContext;
import org.apache.synapse.core.SynapseEnvironment;
import org.apache.synapse.rest.AbstractHandler;
import org.wso2.carbon.identity.oauth2.stub.dto.OAuth2TokenValidationRequestDTO_OAuth2AccessToken;

import java.rmi.RemoteException;
import java.util.Map;

public class SimpleOauthHandler extends AbstractHandler implements ManagedLifecycle {

    private static final String securityHeader = HttpHeaders.AUTHORIZATION;
    private static final String consumerKeyHeaderSegment = "Bearer";
    private static final String oauthHeaderSplitter = ",";
    private static final String consumerKeySegmentDelimiter = " ";
    private static final String oauth2TokenValidationService = "oauth2TokenValidationService";
    private static final String identityServerUserName = "identityServerUserName";
    private static final String identityServerPw = "identityServerPw";
    private static final String BEARER_TOKEN_TYPE = "bearer";

    @Override
    public boolean handleRequest(MessageContext messageContext) {
        try {
            ConfigurationContext configCtx = ConfigurationContextFactory.createConfigurationContextFromFileSystem(null, null);
            //Read parameters from axis2.xml
            String identityServerUrl = messageContext.getConfiguration().getAxisConfiguration().getParameter(oauth2TokenValidationService).getValue().toString();
            String username = messageContext.getConfiguration().getAxisConfiguration().getParameter(identityServerUserName).getValue().toString();
            String password = messageContext.getConfiguration().getAxisConfiguration().getParameter(identityServerPw).getValue().toString();

            OAuth2TokenValidationServiceStub stub = new OAuth2TokenValidationServiceStub(configCtx, identityServerUrl);
            ServiceClient client = stub._getServiceClient();
            Options options = client.getOptions();
            HttpTransportProperties.Authenticator authenticator = new HttpTransportProperties.Authenticator();
            authenticator.setUsername(username);
            authenticator.setPassword(password);
            authenticator.setPreemptiveAuthentication(true);

            options.setProperty(HTTPConstants.AUTHENTICATE, authenticator);
            client.setOptions(options);

            Map headers = (Map) ((Axis2MessageContext) messageContext).getAxis2MessageContext().
                    getProperty(org.apache.axis2.context.MessageContext.TRANSPORT_HEADERS);
            String apiKey = null;
            if (headers != null) {
                apiKey = extractCustomerKeyFromAuthHeader(headers);
            }

            OAuth2TokenValidationRequestDTO oauthReq = new OAuth2TokenValidationRequestDTO();
            OAuth2TokenValidationRequestDTO_OAuth2AccessToken accessToken =
                    new org.wso2.carbon.identity.oauth2.stub.dto.OAuth2TokenValidationRequestDTO_OAuth2AccessToken();
            accessToken.setTokenType(BEARER_TOKEN_TYPE);
            accessToken.setIdentifier(apiKey);
            oauthReq.setAccessToken(accessToken);
            try {
                return stub.validate(oauthReq).getValid();
            } catch (RemoteException e) {
                throw new Exception("Error while validating OAuth2 request", e);
            }
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

    public String extractCustomerKeyFromAuthHeader(Map headersMap) {
        String authHeader = (String) headersMap.get(securityHeader);
        if (authHeader == null) {
            return null;
        }

        if (authHeader.startsWith("OAuth ") || authHeader.startsWith("oauth ")) {
            authHeader = authHeader.substring(authHeader.indexOf("o"));
        }

        String[] headers = authHeader.split(oauthHeaderSplitter);
        if (headers != null) {
            for (int i = 0; i < headers.length; i++) {
                String[] elements = headers[i].split(consumerKeySegmentDelimiter);
                if (elements != null && elements.length > 1) {
                    int j = 0;
                    boolean isConsumerKeyHeaderAvailable = false;
                    for (String element : elements) {
                        if (!"".equals(element.trim())) {
                            if (consumerKeyHeaderSegment.equals(elements[j].trim())) {
                                isConsumerKeyHeaderAvailable = true;
                            } else if (isConsumerKeyHeaderAvailable) {
                                return removeLeadingAndTrailing(elements[j].trim());
                            }
                        }
                        j++;
                    }
                }
            }
        }
        return null;
    }

    private String removeLeadingAndTrailing(String base) {
        String result = base;

        if (base.startsWith("\"") || base.endsWith("\"")) {
            result = base.replace("\"", "");
        }
        return result.trim();
    }

    @Override
    public boolean handleResponse(MessageContext messageContext) {
        return true;
    }

    @Override
    public void init(SynapseEnvironment synapseEnvironment) {
        //To change body of implemented methods use File | Settings | File Templates.
    }

    @Override
    public void destroy() {
        //To change body of implemented methods use File | Settings | File Templates.
    }
}