# ClientSSLSetupHandler.java

    /*
     *  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,
     *  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.apache.synapse.transport.http.conn;

    import java.net.InetSocketAddress;
    import java.net.SocketAddress;
    import java.net.URI;
    import java.net.URISyntaxException;
    import java.util.Arrays;

    import javax.net.ssl.SSLEngine;
    import javax.net.ssl.SSLException;
    import javax.net.ssl.SSLSession;

    import org.apache.http.conn.ssl.AbstractVerifier;
    import org.apache.http.conn.ssl.X509HostnameVerifier;
    import org.apache.http.nio.reactor.IOSession;
    import org.apache.http.nio.reactor.ssl.SSLSetupHandler;
    import org.apache.synapse.transport.certificatevalidation.CertificateVerificationException;
    import org.apache.synapse.transport.certificatevalidation.CertificateVerificationManager;

    public class ClientSSLSetupHandler implements SSLSetupHandler {

        private final static String[] LOCALHOSTS = {"::1", "127.0.0.1",
                "localhost",
                "localhost.localdomain"};

        /** Enabled SSL handshake protocols (e.g. SSLv3, TLSv1) */
        private String[] httpsProtocols;

        /**
         * Preferred Cipher suites config (e.g. TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384,TLS_RSA_WITH_AES_256_CBC_SHA256)
         **/
        private String[] preferredCiphers;

        static {
            Arrays.sort(LOCALHOSTS);
        }

        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;
        }

        /**
         * 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".
         */
        public final static X509HostnameVerifier DEFAULT = new AbstractVerifier() {

            public void verify(
                    final String host, final String[] cns, final String[] subjectAlts) throws SSLException {
                verify(host, cns, subjectAlts, false);
            }

        };

        /**
         * 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.
         */
        public final static X509HostnameVerifier DEFAULT_AND_LOCALHOST = new AbstractVerifier() {

            public void verify(
                    final String host, final String[] cns, final String[] subjectAlts) throws SSLException {
                if (isLocalhost(host)) {
                    return;
                }
                verify(host, cns, subjectAlts, false);
            }
        };

        /**
         * 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".
         */
        public final static X509HostnameVerifier STRICT = new AbstractVerifier() {

            public void verify(
                    final String host, final String[] cns, final String[] subjectAlts) throws SSLException {
                verify(host, cns, subjectAlts, true);
            }

        };

        /**
         * The ALLOW_ALL HostnameVerifier essentially turns hostname verification
         * off.  This implementation is a no-op, and never throws the SSLException.
         */
        public final static X509HostnameVerifier ALLOW_ALL = new AbstractVerifier() {

            public void verify(
                    final String host, final String[] cns, final String[] subjectAlts) throws SSLException {
            }

        };

        private final X509HostnameVerifier hostnameVerifier;
        private final CertificateVerificationManager verificationManager;

        public ClientSSLSetupHandler(final X509HostnameVerifier hostnameVerifier,
                                     final CertificateVerificationManager verificationManager) {
            this.hostnameVerifier = hostnameVerifier != null ? hostnameVerifier : DEFAULT;
            this.verificationManager = verificationManager;
        }

        public void initalize(SSLEngine sslengine) {
            /*
                set handshake protocols if they are specified in transport configuration.
                eg: <parameter name="HttpsProtocols">TLSv1.1,TLSv1.2</parameter>
            */
            if(null != httpsProtocols) {
                sslengine.setEnabledProtocols(httpsProtocols);
            }

            if (preferredCiphers != null) {
                sslengine.setEnabledCipherSuites(preferredCiphers);
            }
        }

        public void verify(IOSession iosession, SSLSession sslsession) throws SSLException {
            SocketAddress remoteAddress = iosession.getRemoteAddress();
            String address;
            String endpoint = (String) iosession.getAttribute(SynapseHTTPRequestFactory.ENDPOINT_URL);
            if (endpoint != null && !endpoint.isEmpty()) {
                try {
                    URI endpointURI = new URI(endpoint);
                    address = endpointURI.getHost();
                } catch (URISyntaxException e) {
                    throw new IllegalArgumentException("Invalid endpointURI: "+ endpoint, e);
                }

            } else if (remoteAddress instanceof InetSocketAddress) {
                address = ((InetSocketAddress) remoteAddress).getHostName();
            } else {
                address = remoteAddress.toString();
            }
            if (!hostnameVerifier.verify(address, sslsession)) {
                throw new SSLException("Host name verification failed for host : " + address);
            }

            if (verificationManager!=null) {
                try {
                    verificationManager.verifyCertificateValidity(sslsession.getPeerCertificateChain());
                } catch (CertificateVerificationException e) {
                    throw new SSLException("Certificate Chain Validation failed for host : " + address, e);
                }
            }
        }

        /**
         * Set HTTPS protocols if mentioned in axis2 configuration
         *
         * @param httpsProtocols  Array of protocols
         */
        public void setHttpsProtocols(String[] httpsProtocols) {
            this.httpsProtocols = httpsProtocols;
        }

        /**
         * Set the enabled Cipher suites. All the ciphers will be enabled if not specified
         *
         * @param enabledCiphers Array of ciphers
         */
        public void setPreferredCiphers(String[] enabledCiphers) {
            this.preferredCiphers = enabledCiphers;
        }

    }