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Android example source code file (DomainNameValidator.java)

This example Android source code file (DomainNameValidator.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

alt_dns_name, alt_ipa_name, android, certificateparsingexception, collection, debug, domainnamevalidator, integer, iterator, list, log_enabled, net, network, patternsyntaxexception, quick_ip_pattern, regex, string, tag, util, utilities

The DomainNameValidator.java Android example source code

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * 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 com.android.internal.net;


import android.util.Config;
import android.util.Log;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.security.cert.CertificateParsingException;
import java.security.cert.X509Certificate;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

import javax.security.auth.x500.X500Principal;

/** @hide */
public class DomainNameValidator {
    private final static String TAG = "DomainNameValidator";

    private static final boolean DEBUG = false;
    private static final boolean LOG_ENABLED = DEBUG ? Config.LOGD : Config.LOGV;

    private static Pattern QUICK_IP_PATTERN;
    static {
        try {
            QUICK_IP_PATTERN = Pattern.compile("^[a-f0-9\\.:]+$");
        } catch (PatternSyntaxException e) {}
    }

    private static final int ALT_DNS_NAME = 2;
    private static final int ALT_IPA_NAME = 7;

    /**
     * Checks the site certificate against the domain name of the site being visited
     * @param certificate The certificate to check
     * @param thisDomain The domain name of the site being visited
     * @return True iff if there is a domain match as specified by RFC2818
     */
    public static boolean match(X509Certificate certificate, String thisDomain) {
        if (certificate == null || thisDomain == null || thisDomain.length() == 0) {
            return false;
        }

        thisDomain = thisDomain.toLowerCase();
        if (!isIpAddress(thisDomain)) {
            return matchDns(certificate, thisDomain);
        } else {
            return matchIpAddress(certificate, thisDomain);
        }
    }

    /**
     * @return True iff the domain name is specified as an IP address
     */
    private static boolean isIpAddress(String domain) {
        boolean rval = (domain != null && domain.length() != 0);
        if (rval) {
            try {
                // do a quick-dirty IP match first to avoid DNS lookup
                rval = QUICK_IP_PATTERN.matcher(domain).matches();
                if (rval) {
                    rval = domain.equals(
                        InetAddress.getByName(domain).getHostAddress());
                }
            } catch (UnknownHostException e) {
                String errorMessage = e.getMessage();
                if (errorMessage == null) {
                  errorMessage = "unknown host exception";
                }

                if (LOG_ENABLED) {
                    Log.v(TAG, "DomainNameValidator.isIpAddress(): " + errorMessage);
                }

                rval = false;
            }
        }

        return rval;
    }

    /**
     * Checks the site certificate against the IP domain name of the site being visited
     * @param certificate The certificate to check
     * @param thisDomain The DNS domain name of the site being visited
     * @return True iff if there is a domain match as specified by RFC2818
     */
    private static boolean matchIpAddress(X509Certificate certificate, String thisDomain) {
        if (LOG_ENABLED) {
            Log.v(TAG, "DomainNameValidator.matchIpAddress(): this domain: " + thisDomain);
        }

        try {
            Collection subjectAltNames = certificate.getSubjectAlternativeNames();
            if (subjectAltNames != null) {
                Iterator i = subjectAltNames.iterator();
                while (i.hasNext()) {
                    List altNameEntry = (List)(i.next());
                    if (altNameEntry != null && 2 <= altNameEntry.size()) {
                        Integer altNameType = (Integer)(altNameEntry.get(0));
                        if (altNameType != null) {
                            if (altNameType.intValue() == ALT_IPA_NAME) {
                                String altName = (String)(altNameEntry.get(1));
                                if (altName != null) {
                                    if (LOG_ENABLED) {
                                        Log.v(TAG, "alternative IP: " + altName);
                                    }
                                    if (thisDomain.equalsIgnoreCase(altName)) {
                                        return true;
                                    }
                                }
                            }
                        }
                    }
                }
            }
        } catch (CertificateParsingException e) {}

        return false;
    }

    /**
     * Checks the site certificate against the DNS domain name of the site being visited
     * @param certificate The certificate to check
     * @param thisDomain The DNS domain name of the site being visited
     * @return True iff if there is a domain match as specified by RFC2818
     */
    private static boolean matchDns(X509Certificate certificate, String thisDomain) {
        boolean hasDns = false;
        try {
            Collection subjectAltNames = certificate.getSubjectAlternativeNames();
            if (subjectAltNames != null) {
                Iterator i = subjectAltNames.iterator();
                while (i.hasNext()) {
                    List altNameEntry = (List)(i.next());
                    if (altNameEntry != null && 2 <= altNameEntry.size()) {
                        Integer altNameType = (Integer)(altNameEntry.get(0));
                        if (altNameType != null) {
                            if (altNameType.intValue() == ALT_DNS_NAME) {
                                hasDns = true;
                                String altName = (String)(altNameEntry.get(1));
                                if (altName != null) {
                                    if (matchDns(thisDomain, altName)) {
                                        return true;
                                    }
                                }
                            }
                        }
                    }
                }
            }
        } catch (CertificateParsingException e) {
            String errorMessage = e.getMessage();
            if (errorMessage == null) {
                errorMessage = "failed to parse certificate";
            }

            Log.w(TAG, "DomainNameValidator.matchDns(): " + errorMessage);
            return false;
        }

        if (!hasDns) {
            final String cn = new DNParser(certificate.getSubjectX500Principal())
                    .find("cn");
            if (LOG_ENABLED) {
                Log.v(TAG, "Validating subject: DN:"
                        + certificate.getSubjectX500Principal().getName(X500Principal.CANONICAL)
                        + "  CN:" + cn);
            }
            if (cn != null) {
                return matchDns(thisDomain, cn);
            }
        }

        return false;
    }

    /**
     * @param thisDomain The domain name of the site being visited
     * @param thatDomain The domain name from the certificate
     * @return True iff thisDomain matches thatDomain as specified by RFC2818
     */
    // not private for testing
    public static boolean matchDns(String thisDomain, String thatDomain) {
        if (LOG_ENABLED) {
            Log.v(TAG, "DomainNameValidator.matchDns():" +
                      " this domain: " + thisDomain +
                      " that domain: " + thatDomain);
        }

        if (thisDomain == null || thisDomain.length() == 0 ||
            thatDomain == null || thatDomain.length() == 0) {
            return false;
        }

        thatDomain = thatDomain.toLowerCase();

        // (a) domain name strings are equal, ignoring case: X matches X
        boolean rval = thisDomain.equals(thatDomain);
        if (!rval) {
            String[] thisDomainTokens = thisDomain.split("\\.");
            String[] thatDomainTokens = thatDomain.split("\\.");

            int thisDomainTokensNum = thisDomainTokens.length;
            int thatDomainTokensNum = thatDomainTokens.length;

            // (b) OR thatHost is a '.'-suffix of thisHost: Z.Y.X matches X
            if (thisDomainTokensNum >= thatDomainTokensNum) {
                for (int i = thatDomainTokensNum - 1; i >= 0; --i) {
                    rval = thisDomainTokens[i].equals(thatDomainTokens[i]);
                    if (!rval) {
                        // (c) OR we have a special *-match:
                        // *.Y.X matches Z.Y.X but *.X doesn't match Z.Y.X
                        rval = (i == 0 && thisDomainTokensNum == thatDomainTokensNum);
                        if (rval) {
                            rval = thatDomainTokens[0].equals("*");
                            if (!rval) {
                                // (d) OR we have a *-component match:
                                // f*.com matches foo.com but not bar.com
                                rval = domainTokenMatch(
                                    thisDomainTokens[0], thatDomainTokens[0]);
                            }
                        }
                        break;
                    }
                }
            } else {
              // (e) OR thatHost has a '*.'-prefix of thisHost:
              // *.Y.X matches Y.X
              rval = thatDomain.equals("*." + thisDomain);
            }
        }

        return rval;
    }

    /**
     * @param thisDomainToken The domain token from the current domain name
     * @param thatDomainToken The domain token from the certificate
     * @return True iff thisDomainToken matches thatDomainToken, using the
     * wildcard match as specified by RFC2818-3.1. For example, f*.com must
     * match foo.com but not bar.com
     */
    private static boolean domainTokenMatch(String thisDomainToken, String thatDomainToken) {
        if (thisDomainToken != null && thatDomainToken != null) {
            int starIndex = thatDomainToken.indexOf('*');
            if (starIndex >= 0) {
                if (thatDomainToken.length() - 1 <= thisDomainToken.length()) {
                    String prefix = thatDomainToken.substring(0,  starIndex);
                    String suffix = thatDomainToken.substring(starIndex + 1);

                    return thisDomainToken.startsWith(prefix) && thisDomainToken.endsWith(suffix);
                }
            }
        }

        return false;
    }
}

Other Android examples (source code examples)

Here is a short list of links related to this Android DomainNameValidator.java source code file:

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