/*

 * Copyright (c) 2013, 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

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 */

package java.net;

import java.io.ObjectInputStream;

import java.io.IOException;

import java.util.List;

import java.util.ArrayList;

import java.util.Collections;

import java.security.Permission;

/**

 * Represents permission to access a resource or set of resources defined by a

 * given url, and for a given set of user-settable request methods

 * and request headers. The <i>name</i> of the permission is the url string.

 * The <i>actions</i> string is a concatenation of the request methods and headers.

 * The range of method and header names is not restricted by this class.

 * <p><b>The url</b><p>

 * The url string has the following expected structure.

 * <pre>

 *     scheme : // authority [ / path ]

 * </pre>

 * <i>scheme</i> will typically be http or https, but is not restricted by this

 * class.

 * <i>authority</i> is specified as:

 * <pre>

 *     authority = [ userinfo @ ] hostrange [ : portrange ]

 *     portrange = portnumber | -portnumber | portnumber-[portnumber] | *

 *     hostrange = ([*.] dnsname) | IPv4address | IPv6address

 * </pre>

 * <i>dnsname</i> is a standard DNS host or domain name, ie. one or more labels

 * separated by ".". <i>IPv4address</i> is a standard literal IPv4 address and

 * <i>IPv6address</i> is as defined in <a href="http://www.ietf.org/rfc/rfc2732.txt">

 * RFC 2732</a>. Literal IPv6 addresses must however, be enclosed in '[]' characters.

 * The <i>dnsname</i> specification can be preceded by "*." which means

 * the name will match any hostname whose right-most domain labels are the same as

 * this name. For example, "*.oracle.com" matches "foo.bar.oracle.com"

 * <p>

 * <i>portrange</i> is used to specify a port number, or a bounded or unbounded range of ports

 * that this permission applies to. If portrange is absent or invalid, then a default

 * port number is assumed if the scheme is {@code http} (default 80) or {@code https}

 * (default 443). No default is assumed for other schemes. A wildcard may be specified

 * which means all ports.

 * <p>

 * <i>userinfo</i> is optional. A userinfo component if present, is ignored when

 * creating a URLPermission, and has no effect on any other methods defined by this class.

 * <p>

 * The <i>path</i> component comprises a sequence of path segments,

 * separated by '/' characters. <i>path</i> may also be empty. The path is specified

 * in a similar way to the path in {@link java.io.FilePermission}. There are

 * three different ways as the following examples show:

 * <table border>

 * <caption>URL Examples</caption>

 * <tr><th>Example url</th><th>Description</th></tr>

 * <tr><td style="white-space:nowrap;">http://www.oracle.com/a/b/c.html</td>

 *   <td>A url which identifies a specific (single) resource</td>

 * </tr>

 * <tr><td>http://www.oracle.com/a/b/*</td>

 *   <td>The '*' character refers to all resources in the same "directory" - in

 *       other words all resources with the same number of path components, and

 *       which only differ in the final path component, represented by the '*'.

 *   </td>

 * </tr>

 * <tr><td>http://www.oracle.com/a/b/-</td>

 *   <td>The '-' character refers to all resources recursively below the

 *       preceding path (eg. http://www.oracle.com/a/b/c/d/e.html matches this

 *       example).

 *   </td>

 * </tr>

 * </table>

 * <p>

 * The '*' and '-' may only be specified in the final segment of a path and must be

 * the only character in that segment. Any query or fragment components of the

 * url are ignored when constructing URLPermissions.

 * <p>

 * As a special case, urls of the form, "scheme:*" are accepted to

 * mean any url of the given scheme.

 * <p>

 * The <i>scheme</i> and <i>authority</i> components of the url string are handled

 * without regard to case. This means {@link #equals(Object)},

 * {@link #hashCode()} and {@link #implies(Permission)} are case insensitive with respect

 * to these components. If the <i>authority</i> contains a literal IP address,

 * then the address is normalized for comparison. The path component is case sensitive.

 * <p><b>The actions string</b><p>

 * The actions string of a URLPermission is a concatenation of the <i>method list</i>

 * and the <i>request headers list</i>. These are lists of the permitted request

 * methods and permitted request headers of the permission (respectively). The two lists

 * are separated by a colon ':' character and elements of each list are comma separated.

 * Some examples are:

 * <pre>

 *         "POST,GET,DELETE"

 *         "GET:X-Foo-Request,X-Bar-Request"

 *         "POST,GET:Header1,Header2"

 * </pre>

 * The first example specifies the methods: POST, GET and DELETE, but no request headers.

 * The second example specifies one request method and two headers. The third

 * example specifies two request methods, and two headers.

 * <p>

 * The colon separator need not be present if the request headers list is empty.

 * No white-space is permitted in the actions string. The action strings supplied to

 * the URLPermission constructors are case-insensitive and are normalized by converting

 * method names to upper-case and header names to the form defines in RFC2616 (lower case

 * with initial letter of each word capitalized). Either list can contain a wild-card '*'

 * character which signifies all request methods or headers respectively.

 * <p>

 * Note. Depending on the context of use, some request methods and headers may be permitted

 * at all times, and others may not be permitted at any time. For example, the

 * HTTP protocol handler might disallow certain headers such as Content-Length

 * from being set by application code, regardless of whether the security policy

 * in force, permits it.

 *

 * @since 1.8

 */

public final class URLPermission extends Permission {

    private static final long serialVersionUID = -2702463814894478682L;

    private transient String scheme;

    private transient String ssp;                 // scheme specific part

    private transient String path;

    private transient List<String> methods;

    private transient List<String> requestHeaders;

    private transient Authority authority;

    // serialized field

    private String actions;

    /**

     * Creates a new URLPermission from a url string and which permits the given

     * request methods and user-settable request headers.

     * The name of the permission is the url string it was created with. Only the scheme,

     * authority and path components of the url are used internally. Any fragment or query

     * components are ignored. The permissions action string is as specified above.

     *

     * @param url the url string

     *

     * @param actions the actions string

     *

     * @exception IllegalArgumentException if url is invalid or if actions contains white-space.

     */

    public URLPermission(String url, String actions) {

        super(url);

        init(actions);

    }

    private void init(String actions) {

        parseURI(getName());

        int colon = actions.indexOf(':');

        if (actions.lastIndexOf(':') != colon) {

            throw new IllegalArgumentException("invalid actions string");

        }

        String methods, headers;

        if (colon == -1) {

            methods = actions;

            headers = "";

        } else {

            methods = actions.substring(0, colon);

            headers = actions.substring(colon+1);

        }

        List<String> l = normalizeMethods(methods);

        Collections.sort(l);

        this.methods = Collections.unmodifiableList(l);

        l = normalizeHeaders(headers);

        Collections.sort(l);

        this.requestHeaders = Collections.unmodifiableList(l);

        this.actions = actions();

    }

    /**

     * Creates a URLPermission with the given url string and unrestricted

     * methods and request headers by invoking the two argument

     * constructor as follows: URLPermission(url, "*:*")

     *

     * @param url the url string

     *

     * @throws    IllegalArgumentException if url does not result in a valid {@link URI}

     */

    public URLPermission(String url) {

        this(url, "*:*");

    }

    /**

     * Returns the normalized method list and request

     * header list, in the form:

     * <pre>

     *      "method-names : header-names"

     * </pre>

     * <p>

     * where method-names is the list of methods separated by commas

     * and header-names is the list of permitted headers separated by commas.

     * There is no white space in the returned String. If header-names is empty

     * then the colon separator will not be present.

     */

    public String getActions() {

        return actions;

    }

    /**

     * Checks if this URLPermission implies the given permission.

     * Specifically, the following checks are done as if in the

     * following sequence:

     * <ul>

     * <li>if 'p' is not an instance of URLPermission return false</li>

     * <li>if any of p's methods are not in this's method list, and if

     *     this's method list is not equal to "*", then return false.</li>

     * <li>if any of p's headers are not in this's request header list, and if

     *     this's request header list is not equal to "*", then return false.</li>

     * <li>if this's url scheme is not equal to p's url scheme return false</li>

     * <li>if the scheme specific part of this's url is '*' return true</li>

     * <li>if the set of hosts defined by p's url hostrange is not a subset of

     *     this's url hostrange then return false. For example, "*.foo.oracle.com"

     *     is a subset of "*.oracle.com". "foo.bar.oracle.com" is not

     *     a subset of "*.foo.oracle.com"</li>

     * <li>if the portrange defined by p's url is not a subset of the

     *     portrange defined by this's url then return false.

     * <li>if the path or paths specified by p's url are contained in the

     *     set of paths specified by this's url, then return true

     * <li>otherwise, return false</li>

     * </ul>

     * <p>Some examples of how paths are matched are shown below:

     * <table border>

     * <caption>Examples of Path Matching</caption>

     * <tr><th>this's path</th><th>p's path</th><th>match</th></tr>

     * <tr><td>/a/b</td><td>/a/b</td><td>yes</td></tr>

     * <tr><td>/a/b/*</td><td>/a/b/c</td><td>yes</td></tr>

     * <tr><td>/a/b/*</td><td>/a/b/c/d</td><td>no</td></tr>

     * <tr><td>/a/b/-</td><td>/a/b/c/d</td><td>yes</td></tr>

     * <tr><td>/a/b/-</td><td>/a/b/c/d/e</td><td>yes</td></tr>

     * <tr><td>/a/b/-</td><td>/a/b/c/*</td><td>yes</td></tr>

     * <tr><td>/a/b/*</td><td>/a/b/c/-</td><td>no</td></tr>

     * </table>

     */

    public boolean implies(Permission p) {

        if (! (p instanceof URLPermission)) {

            return false;

        }

        URLPermission that = (URLPermission)p;

        if (!this.methods.get(0).equals("*") &&

                Collections.indexOfSubList(this.methods, that.methods) == -1) {

            return false;

        }

        if (this.requestHeaders.isEmpty() && !that.requestHeaders.isEmpty()) {

            return false;

        }

        if (!this.requestHeaders.isEmpty() &&

            !this.requestHeaders.get(0).equals("*") &&

             Collections.indexOfSubList(this.requestHeaders,

                                        that.requestHeaders) == -1) {

            return false;

        }

        if (!this.scheme.equals(that.scheme)) {

            return false;

        }

        if (this.ssp.equals("*")) {

            return true;

        }

        if (!this.authority.implies(that.authority)) {

            return false;

        }

        if (this.path == null) {

            return that.path == null;

        }

        if (that.path == null) {

            return false;

        }

        if (this.path.endsWith("/-")) {

            String thisprefix = this.path.substring(0, this.path.length() - 1);

            return that.path.startsWith(thisprefix);

            }

        if (this.path.endsWith("/*")) {

            String thisprefix = this.path.substring(0, this.path.length() - 1);

            if (!that.path.startsWith(thisprefix)) {

                return false;

            }

            String thatsuffix = that.path.substring(thisprefix.length());

            // suffix must not contain '/' chars

            if (thatsuffix.indexOf('/') != -1) {

                return false;

            }

            if (thatsuffix.equals("-")) {

                return false;

            }

            return true;

        }

        return this.path.equals(that.path);

    }

    /**

     * Returns true if, this.getActions().equals(p.getActions())

     * and p's url equals this's url.  Returns false otherwise.

     */

    public boolean equals(Object p) {

        if (!(p instanceof URLPermission)) {

            return false;

        }

        URLPermission that = (URLPermission)p;

        if (!this.scheme.equals(that.scheme)) {

            return false;

        }

        if (!this.getActions().equals(that.getActions())) {

            return false;

        }

        if (!this.authority.equals(that.authority)) {

            return false;

        }

        if (this.path != null) {

            return this.path.equals(that.path);

        } else {

            return that.path == null;

        }

    }

    /**

     * Returns a hashcode calculated from the hashcode of the

     * actions String and the url string.

     */

    public int hashCode() {

        return getActions().hashCode()

            + scheme.hashCode()

            + authority.hashCode()

            + (path == null ? 0 : path.hashCode());

    }

    private List<String> normalizeMethods(String methods) {

        List<String> l = new ArrayList<>();

        StringBuilder b = new StringBuilder();

        for (int i=0; i<methods.length(); i++) {

            char c = methods.charAt(i);

            if (c == ',') {

                String s = b.toString();

                if (s.length() > 0)

                    l.add(s);

                b = new StringBuilder();

            } else if (c == ' ' || c == '\t') {

                throw new IllegalArgumentException("white space not allowed");

            } else {

                if (c >= 'a' && c <= 'z') {

                    c += 'A' - 'a';

                }

                b.append(c);

            }

        }

        String s = b.toString();

        if (s.length() > 0)

            l.add(s);

        return l;

    }

    private List<String> normalizeHeaders(String headers) {

        List<String> l = new ArrayList<>();

        StringBuilder b = new StringBuilder();

        boolean capitalizeNext = true;

        for (int i=0; i<headers.length(); i++) {

            char c = headers.charAt(i);

            if (c >= 'a' && c <= 'z') {

                if (capitalizeNext) {

                    c += 'A' - 'a';

                    capitalizeNext = false;

                }

                b.append(c);

            } else if (c == ' ' || c == '\t') {

                throw new IllegalArgumentException("white space not allowed");

            } else if (c == '-') {

                    capitalizeNext = true;

                b.append(c);

            } else if (c == ',') {

                String s = b.toString();

                if (s.length() > 0)

                    l.add(s);

                b = new StringBuilder();

                capitalizeNext = true;

            } else {

                capitalizeNext = false;

                b.append(c);

            }

        }

        String s = b.toString();

        if (s.length() > 0)

            l.add(s);

        return l;

    }

    private void parseURI(String url) {

        int len = url.length();

        int delim = url.indexOf(':');

        if (delim == -1 || delim + 1 == len) {

            throw new IllegalArgumentException("invalid URL string");

        }

        scheme = url.substring(0, delim).toLowerCase();

        this.ssp = url.substring(delim + 1);

        if (!ssp.startsWith("//")) {

            if (!ssp.equals("*")) {

                throw new IllegalArgumentException("invalid URL string");

            }

            this.authority = new Authority(scheme, "*");

            return;

        }

        String authpath = ssp.substring(2);

        delim = authpath.indexOf('/');

        String auth;

        if (delim == -1) {

            this.path = "";

            auth = authpath;

        } else {

            auth = authpath.substring(0, delim);

            this.path = authpath.substring(delim);

        }

        this.authority = new Authority(scheme, auth.toLowerCase());

    }

    private String actions() {

        StringBuilder b = new StringBuilder();

        for (String s : methods) {

            b.append(s);

        }

        b.append(":");

        for (String s : requestHeaders) {

            b.append(s);

        }

        return b.toString();

    }

    /**

     * restore the state of this object from stream

     */

    private void readObject(ObjectInputStream s)

        throws IOException, ClassNotFoundException {

        ObjectInputStream.GetField fields = s.readFields();

        String actions = (String)fields.get("actions", null);

        init(actions);

    }

    static class Authority {

        HostPortrange p;

        Authority(String scheme, String authority) {

            int at = authority.indexOf('@');

            if (at == -1) {

                    p = new HostPortrange(scheme, authority);

            } else {

                    p = new HostPortrange(scheme, authority.substring(at+1));

            }

        }

        boolean implies(Authority other) {

            return impliesHostrange(other) && impliesPortrange(other);

        }

        private boolean impliesHostrange(Authority that) {

            String thishost = this.p.hostname();

            String thathost = that.p.hostname();

            if (p.wildcard() && thishost.equals("")) {

                // this "*" implies all others

                return true;

            }

            if (that.p.wildcard() && thathost.equals("")) {

                // that "*" can only be implied by this "*"

                return false;

            }

            if (thishost.equals(thathost)) {

                // covers all cases of literal IP addresses and fixed

                // domain names.

                return true;

            }

            if (this.p.wildcard()) {

                // this "*.foo.com" implies "bub.bar.foo.com"

                return thathost.endsWith(thishost);