GHEventPayload.java

package org.jenkinsci.plugins.github.webhook;

import com.cloudbees.jenkins.GitHubWebHook;
import com.google.common.base.Charsets;
import com.google.common.base.Function;
import com.google.common.collect.ImmutableMap;
import org.apache.commons.io.IOUtils;
import org.jenkinsci.plugins.github.util.misc.NullSafeFunction;
import org.kohsuke.stapler.AnnotationHandler;
import org.kohsuke.stapler.InjectedParameter;
import org.kohsuke.stapler.StaplerRequest;
import org.slf4j.Logger;

import javax.annotation.Nonnull;
import javax.servlet.ServletException;
import java.io.IOException;
import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import java.util.Map;

import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static org.apache.commons.lang3.Validate.notNull;
import static org.slf4j.LoggerFactory.getLogger;

/**
 * InjectedParameter annotation to use on WebMethod parameters.
 * Handles GitHub's payload of webhook
 *
 * @author lanwen (Merkushev Kirill)
 * @see <a href=https://wiki.jenkins-ci.org/display/JENKINS/Web+Method>Web Method</a>
 */
@Retention(RUNTIME)
@Target(PARAMETER)
@Documented
@InjectedParameter(GHEventPayload.PayloadHandler.class)
public @interface GHEventPayload {
    class PayloadHandler extends AnnotationHandler<GHEventPayload> {
        private static final Logger LOGGER = getLogger(PayloadHandler.class);

        public static final String APPLICATION_JSON = "application/json";
        public static final String FORM_URLENCODED = "application/x-www-form-urlencoded";
        /**
         * Registered handlers of specified content-types
         *
         * @see <a href=https://developer.github.com/webhooks/creating/#content-type>Developer manual</a>
         */
        private static final Map<String, Function<StaplerRequest, String>> PAYLOAD_PROCESS =
                ImmutableMap.<String, Function<StaplerRequest, String>>builder()
                        .put(APPLICATION_JSON, fromApplicationJson())
                        .put(FORM_URLENCODED, fromForm())
                        .build();

        /**
         * @param type string type expected
         *
         * @return String payload extracted from request or null on any problem
         */
        @Override
        public Object parse(StaplerRequest req, GHEventPayload a, Class type, String param) throws ServletException {
            if (notNull(req, "Why StaplerRequest is null?").getHeader(GitHubWebHook.URL_VALIDATION_HEADER) != null) {
                // if self test for custom hook url
                return null;
            }

            String contentType = req.getContentType();

            if (!PAYLOAD_PROCESS.containsKey(contentType)) {
                LOGGER.error("Unknown content type {}", contentType);
                return null;
            }

            String payload = PAYLOAD_PROCESS.get(contentType).apply(req);

            LOGGER.trace("Payload {}", payload);
            return payload;
        }

        /**
         * used for application/x-www-form-urlencoded content-type
         *
         * @return function to extract payload from form request parameters
         */
        protected static Function<StaplerRequest, String> fromForm() {
            return new NullSafeFunction<StaplerRequest, String>() {
                @Override
                protected String applyNullSafe(@Nonnull StaplerRequest request) {
                    return request.getParameter("payload");
                }
            };
        }

        /**
         * used for application/json content-type
         *
         * @return function to extract payload from body
         */
        protected static Function<StaplerRequest, String> fromApplicationJson() {
            return new NullSafeFunction<StaplerRequest, String>() {
                @Override
                protected String applyNullSafe(@Nonnull StaplerRequest request) {
                    try {
                        return IOUtils.toString(request.getInputStream(), Charsets.UTF_8);
                    } catch (IOException e) {
                        LOGGER.error("Can't get payload from request: {}", e.getMessage());
                        return null;
                    }
                }
            };
        }
    }
}