org.mitre.discovery.util.WebfingerURLNormalizer.java Source code

Introduction

Here is the source code for org.mitre.discovery.util.WebfingerURLNormalizer.java

Source

/*******************************************************************************
 * Copyright 2016 The MITRE Corporation
 *   and the MIT Internet Trust Consortium
 *
 * 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 org.mitre.discovery.util;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.StringUtils;
import org.springframework.web.util.UriComponents;
import org.springframework.web.util.UriComponentsBuilder;

import com.google.common.base.Strings;

/**
 * Provides utility methods for normalizing and parsing URIs for use with Webfinger Discovery.
 * 
 * @author wkim
 *
 */
public class WebfingerURLNormalizer {

    /**
     * Logger for this class
     */
    private static final Logger logger = LoggerFactory.getLogger(WebfingerURLNormalizer.class);

    // pattern used to parse user input; we can't use the built-in java URI parser
    private static final Pattern pattern = Pattern.compile("^" + "((https|acct|http|mailto|tel|device):(//)?)?" + // scheme
            "(" + "(([^@]+)@)?" + // userinfo
            "(([^\\?#:/]+)" + // host
            "(:(\\d*))?)" + // port
            ")" + "([^\\?#]+)?" + // path
            "(\\?([^#]+))?" + // query
            "(#(.*))?" + // fragment
            "$");

    /**
     * Private constructor to prevent instantiation.
     */
    private WebfingerURLNormalizer() {
        // intentionally blank
    }

    /**
     * Normalize the resource string as per OIDC Discovery.
     * @param identifier
     * @return the normalized string, or null if the string can't be normalized
     */
    public static UriComponents normalizeResource(String identifier) {
        // try to parse the URI
        // NOTE: we can't use the Java built-in URI class because it doesn't split the parts appropriately

        if (Strings.isNullOrEmpty(identifier)) {
            logger.warn("Can't normalize null or empty URI: " + identifier);
            return null; // nothing we can do
        } else {

            //UriComponentsBuilder builder = UriComponentsBuilder.fromUriString(identifier);
            UriComponentsBuilder builder = UriComponentsBuilder.newInstance();

            Matcher m = pattern.matcher(identifier);
            if (m.matches()) {
                builder.scheme(m.group(2));
                builder.userInfo(m.group(6));
                builder.host(m.group(8));
                String port = m.group(10);
                if (!Strings.isNullOrEmpty(port)) {
                    builder.port(Integer.parseInt(port));
                }
                builder.path(m.group(11));
                builder.query(m.group(13));
                builder.fragment(m.group(15)); // we throw away the hash, but this is the group it would be if we kept it
            } else {
                // doesn't match the pattern, throw it out
                logger.warn("Parser couldn't match input: " + identifier);
                return null;
            }

            UriComponents n = builder.build();

            if (Strings.isNullOrEmpty(n.getScheme())) {
                if (!Strings.isNullOrEmpty(n.getUserInfo()) && Strings.isNullOrEmpty(n.getPath())
                        && Strings.isNullOrEmpty(n.getQuery()) && n.getPort() < 0) {

                    // scheme empty, userinfo is not empty, path/query/port are empty
                    // set to "acct" (rule 2)
                    builder.scheme("acct");

                } else {
                    // scheme is empty, but rule 2 doesn't apply
                    // set scheme to "https" (rule 3)
                    builder.scheme("https");
                }
            }

            // fragment must be stripped (rule 4)
            builder.fragment(null);

            return builder.build();
        }

    }

    public static String serializeURL(UriComponents uri) {
        if (uri.getScheme() != null && (uri.getScheme().equals("acct") || uri.getScheme().equals("mailto")
                || uri.getScheme().equals("tel") || uri.getScheme().equals("device"))) {

            // serializer copied from HierarchicalUriComponents but with "//" removed

            StringBuilder uriBuilder = new StringBuilder();

            if (uri.getScheme() != null) {
                uriBuilder.append(uri.getScheme());
                uriBuilder.append(':');
            }

            if (uri.getUserInfo() != null || uri.getHost() != null) {
                if (uri.getUserInfo() != null) {
                    uriBuilder.append(uri.getUserInfo());
                    uriBuilder.append('@');
                }
                if (uri.getHost() != null) {
                    uriBuilder.append(uri.getHost());
                }
                if (uri.getPort() != -1) {
                    uriBuilder.append(':');
                    uriBuilder.append(uri.getPort());
                }
            }

            String path = uri.getPath();
            if (StringUtils.hasLength(path)) {
                if (uriBuilder.length() != 0 && path.charAt(0) != '/') {
                    uriBuilder.append('/');
                }
                uriBuilder.append(path);
            }

            String query = uri.getQuery();
            if (query != null) {
                uriBuilder.append('?');
                uriBuilder.append(query);
            }

            if (uri.getFragment() != null) {
                uriBuilder.append('#');
                uriBuilder.append(uri.getFragment());
            }

            return uriBuilder.toString();
        } else {
            return uri.toUriString();
        }

    }

}