The Apache CXF CertificateHostnameVerifier.java source code
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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,
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* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.cxf.transport.https;
import java.io.IOException;
import java.io.InputStream;
import java.security.cert.Certificate;
import java.security.cert.CertificateParsingException;
import java.security.cert.X509Certificate;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.TreeSet;
import javax.net.ssl.SSLException;
import javax.net.ssl.SSLPeerUnverifiedException;
import javax.net.ssl.SSLSession;
import javax.net.ssl.SSLSocket;
/**
* ************************************************************************
* Copied from the not-yet-commons-ssl project at http://juliusdavies.ca/commons-ssl/
* As the above project is accepted into Apache and its JARs become available in
* the Maven 2 repos, we will have to switch to using the JARs instead
* ************************************************************************
* <p/>
* Interface for checking if a hostname matches the names stored inside the
* server's X.509 certificate. Correctly implements
* javax.net.ssl.HostnameVerifier, but that interface is not recommended.
* Instead we added several check() methods that take SSLSocket,
* or X509Certificate, or ultimately (they all end up calling this one),
* String. (It's easier to supply JUnit with Strings instead of mock
* SSLSession objects!)
* </p>Our check() methods throw exceptions if the name is
* invalid, whereas javax.net.ssl.HostnameVerifier just returns true/false.
* <p/>
* We provide the HostnameVerifier.DEFAULT, HostnameVerifier.STRICT, and
* HostnameVerifier.ALLOW_ALL implementations. We also provide the more
* specialized HostnameVerifier.DEFAULT_AND_LOCALHOST, as well as
* HostnameVerifier.STRICT_IE6. But feel free to define your own
* implementations!
* <p/>
* Inspired by Sebastian Hauer's original StrictSSLProtocolSocketFactory in the
* HttpClient "contrib" repository.
*
* @author Julius Davies
* @author <a href="mailto:hauer@psicode.com">Sebastian Hauer
* @since 8-Dec-2006
*/
public interface CertificateHostnameVerifier extends javax.net.ssl.HostnameVerifier {
/**
* The DEFAULT HostnameVerifier works the same way as Curl and Firefox.
* <p/>
* The hostname must match either the first CN, or any of the subject-alts.
* A wildcard can occur in the CN, and in any of the subject-alts.
* <p/>
* The only difference between DEFAULT and STRICT is that a wildcard (such
* as "*.foo.com") with DEFAULT matches all subdomains, including
* "a.b.foo.com".
*/
CertificateHostnameVerifier DEFAULT =
new AbstractVerifier() {
public final void check(final String[] hosts, final String[] cns,
final String[] subjectAlts)
throws SSLException {
check(hosts, cns, subjectAlts, false, false);
}
public final String toString() {
return "DEFAULT";
}
};
/**
* The DEFAULT_AND_LOCALHOST HostnameVerifier works like the DEFAULT
* one with one additional relaxation: a host of "localhost",
* "localhost.localdomain", "127.0.0.1", "::1" will always pass, no matter
* what is in the server's certificate.
*/
CertificateHostnameVerifier DEFAULT_AND_LOCALHOST =
new AbstractVerifier() {
public final void check(final String[] hosts, final String[] cns,
final String[] subjectAlts)
throws SSLException {
if (isLocalhost(hosts[0])) {
return;
}
check(hosts, cns, subjectAlts, false, false);
}
public final String toString() {
return "DEFAULT_AND_LOCALHOST";
}
};
/**
* The STRICT HostnameVerifier works the same way as java.net.URL in Sun
* Java 1.4, Sun Java 5, Sun Java 6. It's also pretty close to IE6.
* This implementation appears to be compliant with RFC 2818 for dealing
* with wildcards.
* <p/>
* The hostname must match either the first CN, or any of the subject-alts.
* A wildcard can occur in the CN, and in any of the subject-alts. The
* one divergence from IE6 is how we only check the first CN. IE6 allows
* a match against any of the CNs present. We decided to follow in
* Sun Java 1.4's footsteps and only check the first CN.
* <p/>
* A wildcard such as "*.foo.com" matches only subdomains in the same
* level, for example "a.foo.com". It does not match deeper subdomains
* such as "a.b.foo.com".
*/
CertificateHostnameVerifier STRICT =
new AbstractVerifier() {
public final void check(final String[] host, final String[] cns,
final String[] subjectAlts)
throws SSLException {
check(host, cns, subjectAlts, false, true);
}
public final String toString() {
return "STRICT";
}
};
/**
* The STRICT_IE6 HostnameVerifier works just like the STRICT one with one
* minor variation: the hostname can match against any of the CN's in the
* server's certificate, not just the first one. This behaviour is
* identical to IE6's behaviour.
*/
CertificateHostnameVerifier STRICT_IE6 =
new AbstractVerifier() {
public final void check(final String[] host, final String[] cns,
final String[] subjectAlts)
throws SSLException {
check(host, cns, subjectAlts, true, true);
}
public final String toString() {
return "STRICT_IE6";
}
};
/**
* The ALLOW_ALL HostnameVerifier essentially turns hostname verification
* off. This implementation is a no-op, and never throws the SSLException.
*/
CertificateHostnameVerifier ALLOW_ALL =
new AbstractVerifier() {
public final void check(final String[] host, final String[] cns,
final String[] subjectAlts) {
// Allow everything - so never blowup.
}
public final String toString() {
return "ALLOW_ALL";
}
};
boolean verify(String host, SSLSession session);
void check(String host, SSLSocket ssl) throws IOException;
void check(String host, X509Certificate cert) throws SSLException;
void check(String host, String[] cns, String[] subjectAlts)
throws SSLException;
void check(String[] hosts, SSLSocket ssl) throws IOException;
void check(String[] hosts, X509Certificate cert) throws SSLException;
/**
* Checks to see if the supplied hostname matches any of the supplied CNs
* or "DNS" Subject-Alts. Most implementations only look at the first CN,
* and ignore any additional CNs. Most implementations do look at all of
* the "DNS" Subject-Alts. The CNs or Subject-Alts may contain wildcards
* according to RFC 2818.
*
* @param cns CN fields, in order, as extracted from the X.509
* certificate.
* @param subjectAlts Subject-Alt fields of type 2 ("DNS"), as extracted
* from the X.509 certificate.
* @param hosts The array of hostnames to verify.
* @throws SSLException If verification failed.
*/
void check(String[] hosts, String[] cns, String[] subjectAlts)
throws SSLException;
abstract class AbstractVerifier implements CertificateHostnameVerifier {
/**
* This contains a list of 2nd-level domains that aren't allowed to
* have wildcards when combined with country-codes.
* For example: [*.co.uk].
* <p/>
* The [*.co.uk] problem is an interesting one. Should we just hope
* that CA's would never foolishly allow such a certificate to happen?
* Looks like we're the only implementation guarding against this.
* Firefox, Curl, Sun Java 1.4, 5, 6 don't bother with this check.
*/
private static final String[] BAD_COUNTRY_2LDS = {
"ac", "co", "com", "ed", "edu", "go", "gouv", "gov", "info",
"lg", "ne", "net", "or", "org"};
private static final String[] LOCALHOSTS = {
"::1", "127.0.0.1",
"localhost",
"localhost.localdomain"};
static {
// Just in case developer forgot to manually sort the array. :-)
Arrays.sort(BAD_COUNTRY_2LDS);
Arrays.sort(LOCALHOSTS);
}
protected AbstractVerifier() {
}
/**
* The javax.net.ssl.HostnameVerifier contract.
*
* @param host 'hostname' we used to create our socket
* @param session SSLSession with the remote server
* @return true if the host matched the one in the certificate.
*/
public boolean verify(String host, SSLSession session) {
try {
Certificate[] certs = session.getPeerCertificates();
X509Certificate x509 = (X509Certificate) certs[0];
check(new String[]{host}, x509);
return true;
} catch (SSLException e) {
return false;
}
}
public void check(String host, SSLSocket ssl) throws IOException {
check(new String[]{host}, ssl);
}
public void check(String host, X509Certificate cert)
throws SSLException {
check(new String[]{host}, cert);
}
public void check(String host, String[] cns, String[] subjectAlts)
throws SSLException {
check(new String[]{host}, cns, subjectAlts);
}
public void check(String host[], SSLSocket ssl)
throws IOException {
if (host == null) {
throw new NullPointerException("host to verify is null");
}
SSLSession session = ssl.getSession();
if (session == null) {
// In our experience this only happens under IBM 1.4.x when
// spurious (unrelated) certificates show up in the server'
// chain. Hopefully this will unearth the real problem:
InputStream in = ssl.getInputStream();
in.available();
/*
If you're looking at the 2 lines of code above because
you're running into a problem, you probably have two
options:
#1. Clean up the certificate chain that your server
is presenting (e.g. edit "/etc/apache2/server.crt"
or wherever it is your server's certificate chain
is defined).
OR
#2. Upgrade to an IBM 1.5.x or greater JVM, or switch
to a non-IBM JVM.
*/
// If ssl.getInputStream().available() didn't cause an
// exception, maybe at least now the session is available?
session = ssl.getSession();
if (session == null) {
// If it's still null, probably a startHandshake() will
// unearth the real problem.
ssl.startHandshake();
// Okay, if we still haven't managed to cause an exception,
// might as well go for the NPE. Or maybe we're okay now?
session = ssl.getSession();
}
}
Certificate[] certs;
try {
certs = session.getPeerCertificates();
} catch (SSLPeerUnverifiedException spue) {
InputStream in = ssl.getInputStream();
in.available();
// Didn't trigger anything interesting? Okay, just throw
// original.
throw spue;
}
X509Certificate x509 = (X509Certificate) certs[0];
check(host, x509);
}
public void check(String[] host, X509Certificate cert)
throws SSLException {
String[] cns = Certificates.getCNs(cert);
String[] subjectAlts = Certificates.getDNSSubjectAlts(cert);
check(host, cns, subjectAlts);
}
public void check(final String[] hosts, final String[] cns,
final String[] subjectAlts, final boolean ie6,
final boolean strictWithSubDomains)
throws SSLException {
// Build up lists of allowed hosts For logging/debugging purposes.
StringBuilder buf = new StringBuilder(32);
buf.append('<');
for (int i = 0; i < hosts.length; i++) {
String h = hosts[i];
h = h != null ? h.trim().toLowerCase() : "";
hosts[i] = h;
if (i > 0) {
buf.append('/');
}
buf.append(h);
}
buf.append('>');
String hostnames = buf.toString();
// Build the list of names we're going to check. Our DEFAULT and
// STRICT implementations of the HostnameVerifier only use the
// first CN provided. All other CNs are ignored.
// (Firefox, wget, curl, Sun Java 1.4, 5, 6 all work this way).
Set<String> names = new TreeSet();
if (cns != null && cns.length > 0 && cns[0] != null) {
names.add(cns[0]);
if (ie6) {
for (int i = 1; i < cns.length; i++) {
names.add(cns[i]);
}
}
}
if (subjectAlts != null) {
for (int i = 0; i < subjectAlts.length; i++) {
if (subjectAlts[i] != null) {
names.add(subjectAlts[i]);
}
}
}
if (names.isEmpty()) {
String msg = "Certificate for " + hosts[0] + " doesn't contain CN or DNS subjectAlt";
throw new SSLException(msg);
}
// StringBuilder for building the error message.
buf = new StringBuilder();
boolean match = false;
out:
for (Iterator<String> it = names.iterator(); it.hasNext();) {
// Don't trim the CN, though!
String cn = it.next();
cn = cn.toLowerCase();
// Store CN in StringBuilder in case we need to report an error.
buf.append(" <");
buf.append(cn);
buf.append('>');
if (it.hasNext()) {
buf.append(" OR");
}
// The CN better have at least two dots if it wants wildcard
// action. It also can't be [*.co.uk] or [*.co.jp] or
// [*.org.uk], etc...
boolean doWildcard = cn.startsWith("*.")
&& cn.lastIndexOf('.') >= 0
&& !isIP4Address(cn)
&& acceptableCountryWildcard(cn);
for (int i = 0; i < hosts.length; i++) {
final String hostName = hosts[i].trim().toLowerCase();
if (doWildcard) {
match = hostName.endsWith(cn.substring(1));
if (match && strictWithSubDomains) {
// If we're in strict mode, then [*.foo.com] is not
// allowed to match [a.b.foo.com]
match = countDots(hostName) == countDots(cn);
}
} else {
match = hostName.equals(cn);
}
if (match) {
break out;
}
}
}
if (!match) {
throw new SSLException("hostname in certificate didn't match: " + hostnames + " !=" + buf);
}
}
public static boolean isIP4Address(final String cn) {
boolean isIP4 = true;
String tld = cn;
int x = cn.lastIndexOf('.');
// We only bother analyzing the characters after the final dot
// in the name.
if (x >= 0 && x + 1 < cn.length()) {
tld = cn.substring(x + 1);
}
for (int i = 0; i < tld.length(); i++) {
if (!Character.isDigit(tld.charAt(0))) {
isIP4 = false;
break;
}
}
return isIP4;
}
public static boolean acceptableCountryWildcard(final String cn) {
int cnLen = cn.length();
if (cnLen >= 7 && cnLen <= 9
// Look for the '.' in the 3rd-last position:
&& cn.charAt(cnLen - 3) == '.') {
// Trim off the [*.] and the [.XX].
String s = cn.substring(2, cnLen - 3);
// And test against the sorted array of bad 2lds:
int x = Arrays.binarySearch(BAD_COUNTRY_2LDS, s);
return x < 0;
}
return true;
}
public static boolean isLocalhost(String host) {
host = host != null ? host.trim().toLowerCase() : "";
if (host.startsWith("::1")) {
int x = host.lastIndexOf('%');
if (x >= 0) {
host = host.substring(0, x);
}
}
int x = Arrays.binarySearch(LOCALHOSTS, host);
return x >= 0;
}
/**
* Counts the number of dots "." in a string.
*
* @param s string to count dots from
* @return number of dots
*/
public static int countDots(final String s) {
int count = 0;
for (int i = 0; i < s.length(); i++) {
if (s.charAt(i) == '.') {
count++;
}
}
return count;
}
}
final class Certificates {
private Certificates() {
//utility class
}
public static String[] getCNs(X509Certificate cert) {
List<String> cnList = new LinkedList();
/*
Sebastian Hauer's original StrictSSLProtocolSocketFactory used
getName() and had the following comment:
Parses a X.500 distinguished name for the value of the
"Common Name" field. This is done a bit sloppy right
now and should probably be done a bit more according to
<code>RFC 2253.
I've noticed that toString() seems to do a better job than
getName() on these X500Principal objects, so I'm hoping that
addresses Sebastian's concern.
For example, getName() gives me this:
1.2.840.113549.1.9.1=#16166a756c6975736461766965734063756362632e636f6d
whereas toString() gives me this:
EMAILADDRESS=juliusdavies@cucbc.com
Looks like toString() even works with non-ascii domain names!
I tested it with "花子.co.jp" and it worked fine.
*/
String subjectPrincipal = cert.getSubjectX500Principal().toString();
StringTokenizer st = new StringTokenizer(subjectPrincipal, ",");
while (st.hasMoreTokens()) {
String tok = st.nextToken();
int x = tok.indexOf("CN=");
if (x >= 0) {
cnList.add(tok.substring(x + 3));
}
}
if (!cnList.isEmpty()) {
String[] cns = new String[cnList.size()];
cnList.toArray(cns);
return cns;
} else {
return null;
}
}
/**
* Extracts the array of SubjectAlt DNS names from an X509Certificate.
* Returns null if there aren't any.
* <p/>
* Note: Java doesn't appear able to extract international characters
* from the SubjectAlts. It can only extract international characters
* from the CN field.
* <p/>
* (Or maybe the version of OpenSSL I'm using to test isn't storing the
* international characters correctly in the SubjectAlts?).
*
* @param cert X509Certificate
* @return Array of SubjectALT DNS names stored in the certificate.
*/
public static String[] getDNSSubjectAlts(X509Certificate cert) {
List<String> subjectAltList = new LinkedList();
Collection<List c = null;
try {
c = cert.getSubjectAlternativeNames();
} catch (CertificateParsingException cpe) {
// Should probably log.debug() this?
cpe.printStackTrace();
}
if (c != null) {
Iterator it = c.iterator();
while (it.hasNext()) {
List list = (List) it.next();
int type = ((Integer) list.get(0)).intValue();
// If type is 2, then we've got a dNSName
if (type == 2) {
String s = (String) list.get(1);
subjectAltList.add(s);
}
}
}
if (!subjectAltList.isEmpty()) {
String[] subjectAlts = new String[subjectAltList.size()];
subjectAltList.toArray(subjectAlts);
return subjectAlts;
} else {
return null;
}
}
}
}
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