/*
 * Copyright (c) 2003, 2020, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package sun.net.spi;

import java.net.InetSocketAddress;
import java.net.Proxy;
import java.net.ProxySelector;
import java.net.SocketAddress;
import java.net.URI;
import java.util.Collections;
import java.util.List;
import java.io.IOException;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.StringJoiner;
import java.util.regex.Pattern;
import java.util.stream.Stream;
import sun.net.NetProperties;
import sun.net.SocksProxy;
import static java.util.regex.Pattern.quote;
import static java.util.stream.Collectors.collectingAndThen;
import static java.util.stream.Collectors.toList;

Supports proxy settings using system properties This proxy selector
provides backward compatibility with the old http protocol handler
as far as how proxy is set
Most of the implementation copied from the old http protocol handler
Supports http/https/ftp.proxyHost, http/https/ftp.proxyPort,
proxyHost, proxyPort, and http/https/ftp.nonProxyHost, and socks.
/**
 * Supports proxy settings using system properties This proxy selector
 * provides backward compatibility with the old http protocol handler
 * as far as how proxy is set
 *
 * Most of the implementation copied from the old http protocol handler
 *
 * Supports http/https/ftp.proxyHost, http/https/ftp.proxyPort,
 * proxyHost, proxyPort, and http/https/ftp.nonProxyHost, and socks.
 */
public class DefaultProxySelector extends ProxySelector {

    
This is where we define all the valid System Properties we have to
support for each given protocol.
The format of this 2 dimensional array is :
- 1 row per protocol (http, ftp, ...)
- 1st element of each row is the protocol name
- subsequent elements are prefixes for Host & Port properties
  listed in order of priority.
Example:
{"ftp", "ftp.proxy", "ftpProxy", "proxy", "socksProxy"},
means for FTP we try in that oder:
         + ftp.proxyHost & ftp.proxyPort
         + ftpProxyHost & ftpProxyPort
         + proxyHost & proxyPort
         + socksProxyHost & socksProxyPort
Note that the socksProxy should *always* be the last on the list
/**
     * This is where we define all the valid System Properties we have to
     * support for each given protocol.
     * The format of this 2 dimensional array is :
     * - 1 row per protocol (http, ftp, ...)
     * - 1st element of each row is the protocol name
     * - subsequent elements are prefixes for Host & Port properties
     *   listed in order of priority.
     * Example:
     * {"ftp", "ftp.proxy", "ftpProxy", "proxy", "socksProxy"},
     * means for FTP we try in that oder:
     *          + ftp.proxyHost & ftp.proxyPort
     *          + ftpProxyHost & ftpProxyPort
     *          + proxyHost & proxyPort
     *          + socksProxyHost & socksProxyPort
     *
     * Note that the socksProxy should *always* be the last on the list
     */
    static final String[][] props = {
        /*
         * protocol, Property prefix 1, Property prefix 2, ...
         */
        {"http", "http.proxy", "proxy", "socksProxy"},
        {"https", "https.proxy", "proxy", "socksProxy"},
        {"ftp", "ftp.proxy", "ftpProxy", "proxy", "socksProxy"},
        {"socket", "socksProxy"}
    };

    private static final String SOCKS_PROXY_VERSION = "socksProxyVersion";

    private static boolean hasSystemProxies = false;

    private static final List<Proxy> NO_PROXY_LIST = List.of(Proxy.NO_PROXY);

    static {
        final String key = "java.net.useSystemProxies";
        Boolean b = AccessController.doPrivileged(
            new PrivilegedAction<Boolean>() {
                public Boolean run() {
                    return NetProperties.getBoolean(key);
                }});
        if (b != null && b.booleanValue()) {
            jdk.internal.loader.BootLoader.loadLibrary("net");
            hasSystemProxies = init();
        }
    }

    public static int socksProxyVersion() {
        return AccessController.doPrivileged(
                new PrivilegedAction<Integer>() {
                    @Override public Integer run() {
                        return NetProperties.getInteger(SOCKS_PROXY_VERSION, 5);
                    }
                });
    }

    
How to deal with "non proxy hosts":
since we do have to generate a pattern we don't want to do that if
it's not necessary. Therefore we do cache the result, on a per-protocol
basis, and change it only when the "source", i.e. the system property,
did change.
/**
     * How to deal with "non proxy hosts":
     * since we do have to generate a pattern we don't want to do that if
     * it's not necessary. Therefore we do cache the result, on a per-protocol
     * basis, and change it only when the "source", i.e. the system property,
     * did change.
     */

    static class NonProxyInfo {
        // Default value for nonProxyHosts, this provides backward compatibility
        // by excluding localhost and its litteral notations.
        static final String defStringVal = "localhost|127.*|[::1]|0.0.0.0|[::0]";

        String hostsSource;
        Pattern pattern;
        final String property;
        final String defaultVal;
        static NonProxyInfo ftpNonProxyInfo = new NonProxyInfo("ftp.nonProxyHosts", null, null, defStringVal);
        static NonProxyInfo httpNonProxyInfo = new NonProxyInfo("http.nonProxyHosts", null, null, defStringVal);
        static NonProxyInfo socksNonProxyInfo = new NonProxyInfo("socksNonProxyHosts", null, null, defStringVal);

        NonProxyInfo(String p, String s, Pattern pattern, String d) {
            property = p;
            hostsSource = s;
            this.pattern = pattern;
            defaultVal = d;
        }
    }


    
select() method. Where all the hard work is done.
Build a list of proxies depending on URI.
Since we're only providing compatibility with the system properties
from previous releases (see list above), that list will typically
contain one single proxy, default being NO_PROXY.
If we can get a system proxy it might contain more entries.
/**
     * select() method. Where all the hard work is done.
     * Build a list of proxies depending on URI.
     * Since we're only providing compatibility with the system properties
     * from previous releases (see list above), that list will typically
     * contain one single proxy, default being NO_PROXY.
     * If we can get a system proxy it might contain more entries.
     */
    public java.util.List<Proxy> select(URI uri) {
        if (uri == null) {
            throw new IllegalArgumentException("URI can't be null.");
        }
        String protocol = uri.getScheme();
        String host = uri.getHost();

        if (host == null) {
            // This is a hack to ensure backward compatibility in two
            // cases: 1. hostnames contain non-ascii characters,
            // internationalized domain names. in which case, URI will
            // return null, see BugID 4957669; 2. Some hostnames can
            // contain '_' chars even though it's not supposed to be
            // legal, in which case URI will return null for getHost,
            // but not for getAuthority() See BugID 4913253
            String auth = uri.getAuthority();
            if (auth != null) {
                int i;
                i = auth.indexOf('@');
                if (i >= 0) {
                    auth = auth.substring(i+1);
                }
                i = auth.lastIndexOf(':');
                if (i >= 0) {
                    auth = auth.substring(0,i);
                }
                host = auth;
            }
        }

        if (protocol == null || host == null) {
            throw new IllegalArgumentException("protocol = "+protocol+" host = "+host);
        }

        NonProxyInfo pinfo = null;

        if ("http".equalsIgnoreCase(protocol)) {
            pinfo = NonProxyInfo.httpNonProxyInfo;
        } else if ("https".equalsIgnoreCase(protocol)) {
            // HTTPS uses the same property as HTTP, for backward
            // compatibility
            pinfo = NonProxyInfo.httpNonProxyInfo;
        } else if ("ftp".equalsIgnoreCase(protocol)) {
            pinfo = NonProxyInfo.ftpNonProxyInfo;
        } else if ("socket".equalsIgnoreCase(protocol)) {
            pinfo = NonProxyInfo.socksNonProxyInfo;
        }

        /**
         * Let's check the System properties for that protocol
         */
        final String proto = protocol;
        final NonProxyInfo nprop = pinfo;
        final String urlhost = host.toLowerCase();

        /**
         * This is one big doPrivileged call, but we're trying to optimize
         * the code as much as possible. Since we're checking quite a few
         * System properties it does help having only 1 call to doPrivileged.
         * Be mindful what you do in here though!
         */
        Proxy[] proxyArray = AccessController.doPrivileged(
            new PrivilegedAction<Proxy[]>() {
                public Proxy[] run() {
                    int i, j;
                    String phost =  null;
                    int pport = 0;
                    String nphosts =  null;
                    InetSocketAddress saddr = null;

                    // Then let's walk the list of protocols in our array
                    for (i=0; i<props.length; i++) {
                        if (props[i][0].equalsIgnoreCase(proto)) {
                            for (j = 1; j < props[i].length; j++) {
                                /* System.getProp() will give us an empty
                                 * String, "" for a defined but "empty"
                                 * property.
                                 */
                                phost =  NetProperties.get(props[i][j]+"Host");
                                if (phost != null && phost.length() != 0)
                                    break;
                            }
                            if (phost == null || phost.isEmpty()) {
                                /**
                                 * No system property defined for that
                                 * protocol. Let's check System Proxy
                                 * settings (Gnome, MacOsX & Windows) if
                                 * we were instructed to.
                                 */
                                if (hasSystemProxies) {
                                    String sproto;
                                    if (proto.equalsIgnoreCase("socket"))
                                        sproto = "socks";
                                    else
                                        sproto = proto;
                                    return getSystemProxies(sproto, urlhost);
                                }
                                return null;
                            }
                            // If a Proxy Host is defined for that protocol
                            // Let's get the NonProxyHosts property
                            if (nprop != null) {
                                nphosts = NetProperties.get(nprop.property);
                                synchronized (nprop) {
                                    if (nphosts == null) {
                                        if (nprop.defaultVal != null) {
                                            nphosts = nprop.defaultVal;
                                        } else {
                                            nprop.hostsSource = null;
                                            nprop.pattern = null;
                                        }
                                    } else if (!nphosts.isEmpty()) {
                                        // add the required default patterns
                                        // but only if property no set. If it
                                        // is empty, leave empty.
                                        nphosts += "|" + NonProxyInfo
                                                         .defStringVal;
                                    }
                                    if (nphosts != null) {
                                        if (!nphosts.equals(nprop.hostsSource)) {
                                            nprop.pattern = toPattern(nphosts);
                                            nprop.hostsSource = nphosts;
                                        }
                                    }
                                    if (shouldNotUseProxyFor(nprop.pattern, urlhost)) {
                                        return null;
                                    }
                                }
                            }
                            // We got a host, let's check for port

                            pport = NetProperties.getInteger(props[i][j]+"Port", 0).intValue();
                            if (pport == 0 && j < (props[i].length - 1)) {
                                // Can't find a port with same prefix as Host
                                // AND it's not a SOCKS proxy
                                // Let's try the other prefixes for that proto
                                for (int k = 1; k < (props[i].length - 1); k++) {
                                    if ((k != j) && (pport == 0))
                                        pport = NetProperties.getInteger(props[i][k]+"Port", 0).intValue();
                                }
                            }

                            // Still couldn't find a port, let's use default
                            if (pport == 0) {
                                if (j == (props[i].length - 1)) // SOCKS
                                    pport = defaultPort("socket");
                                else
                                    pport = defaultPort(proto);
                            }
                            // We did find a proxy definition.
                            // Let's create the address, but don't resolve it
                            // as this will be done at connection time
                            saddr = InetSocketAddress.createUnresolved(phost, pport);
                            // Socks is *always* the last on the list.
                            if (j == (props[i].length - 1)) {
                                return new Proxy[] {SocksProxy.create(saddr, socksProxyVersion())};
                            }
                            return new Proxy[] {new Proxy(Proxy.Type.HTTP, saddr)};
                        }
                    }
                    return null;
                }});


        if (proxyArray != null) {
            // Remove duplicate entries, while preserving order.
            return Stream.of(proxyArray).distinct().collect(
                    collectingAndThen(toList(), Collections::unmodifiableList));
        }

        // If no specific proxy was found, return a standard list containing
        // only one NO_PROXY entry.
        return NO_PROXY_LIST;
    }

    public void connectFailed(URI uri, SocketAddress sa, IOException ioe) {
        if (uri == null || sa == null || ioe == null) {
            throw new IllegalArgumentException("Arguments can't be null.");
        }
        // ignored
    }


    private int defaultPort(String protocol) {
        if ("http".equalsIgnoreCase(protocol)) {
            return 80;
        } else if ("https".equalsIgnoreCase(protocol)) {
            return 443;
        } else if ("ftp".equalsIgnoreCase(protocol)) {
            return 80;
        } else if ("socket".equalsIgnoreCase(protocol)) {
            return 1080;
        } else {
            return -1;
        }
    }

    private static native boolean init();
    private synchronized native Proxy[] getSystemProxies(String protocol, String host);

    
Returns:
true if given this pattern for non-proxy hosts and this urlhost the proxy should NOT be used to access this urlhost/**
     * @return {@code true} if given this pattern for non-proxy hosts and this
     *         urlhost the proxy should NOT be used to access this urlhost
     */
    static boolean shouldNotUseProxyFor(Pattern pattern, String urlhost) {
        if (pattern == null || urlhost.isEmpty())
            return false;
        boolean matches = pattern.matcher(urlhost).matches();
        return matches;
    }

    
Params:
mask – non-null mask
Returns:
Pattern corresponding to this mask or null in case mask should not match anything/**
     * @param mask non-null mask
     * @return {@link java.util.regex.Pattern} corresponding to this mask
     *         or {@code null} in case mask should not match anything
     */
    static Pattern toPattern(String mask) {
        boolean disjunctionEmpty = true;
        StringJoiner joiner = new StringJoiner("|");
        for (String disjunct : mask.split("\\|")) {
            if (disjunct.isEmpty())
                continue;
            disjunctionEmpty = false;
            String regex = disjunctToRegex(disjunct.toLowerCase());
            joiner.add(regex);
        }
        return disjunctionEmpty ? null : Pattern.compile(joiner.toString());
    }

    
Params:
disjunct – non-null mask disjunct
Returns:
java regex string corresponding to this mask/**
     * @param disjunct non-null mask disjunct
     * @return java regex string corresponding to this mask
     */
    static String disjunctToRegex(String disjunct) {
        String regex;
        if (disjunct.equals("*")) {
            regex = ".*";
        } else if (disjunct.startsWith("*") && disjunct.endsWith("*")) {
            regex = ".*" + quote(disjunct.substring(1, disjunct.length() - 1)) + ".*";
        } else if (disjunct.startsWith("*")) {
            regex = ".*" + quote(disjunct.substring(1));
        } else if (disjunct.endsWith("*")) {
            regex = quote(disjunct.substring(0, disjunct.length() - 1)) + ".*";
        } else {
            regex = quote(disjunct);
        }
        return regex;
    }
}