/*
* Copyright (C) 2008 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 android.net.http;
import org.bouncycastle.asn1.x509.X509Name;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.security.cert.X509Certificate;
import java.security.cert.CertificateParsingException;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;
import java.util.Vector;
/**
* Implements basic domain-name validation as specified by RFC2818.
*
* {@hide}
*/
public class DomainNameChecker {
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 (HttpLog.LOGV) {
HttpLog.v("DomainNameChecker.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 (HttpLog.LOGV) {
HttpLog.v("DomainNameChecker.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 (HttpLog.LOGV) {
HttpLog.v("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) {
// one way we can get here is if an alternative name starts with
// '*' character, which is contrary to one interpretation of the
// spec (a valid DNS name must start with a letter); there is no
// good way around this, and in order to be compatible we proceed
// to check the common name (ie, ignore alternative names)
if (HttpLog.LOGV) {
String errorMessage = e.getMessage();
if (errorMessage == null) {
errorMessage = "failed to parse certificate";
}
if (HttpLog.LOGV) {
HttpLog.v("DomainNameChecker.matchDns(): " + errorMessage);
}
}
}
if (!hasDns) {
X509Name xName = new X509Name(certificate.getSubjectDN().getName());
Vector val = xName.getValues();
Vector oid = xName.getOIDs();
for (int i = 0; i < oid.size(); i++) {
if (oid.elementAt(i).equals(X509Name.CN)) {
return matchDns(thisDomain, (String)(val.elementAt(i)));
}
}
}
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
*/
private static boolean matchDns(String thisDomain, String thatDomain) {
if (HttpLog.LOGV) {
HttpLog.v("DomainNameChecker.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:
// Z.Y.X matches *.Y.X but does not match *.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;
}
}
}
}
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;
}
}