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 * Copyright (c) 2013, 2017, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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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 class="striped">
 * <caption>URL Examples</caption>
 * <thead>
 * <tr><th scope="col">Example url</th><th scope="col">Description</th></tr>
 * </thead>
 * <tbody style="text-align:left">
 * <tr><th scope="row" style="white-space:nowrap;">http://www.oracle.com/a/b/c.html</th>
 * <td>A url which identifies a specific (single) resource</td>
 * </tr>
 * <tr><th scope="row">http://www.oracle.com/a/b/*</th>
 * <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><th scope="row">http://www.oracle.com/a/b/-</th>
 * <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>
 * </tbody>
 * </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:
 * <ul>
 * <li>"POST,GET,DELETE"
 * <li>"GET:X-Foo-Request,X-Bar-Request"
 * <li>"POST,GET:Header1,Header2"
 * </ul>
 * <p>
 * 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: \"" + actions + "\"");
 }

 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 may 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 class="plain">
 * <caption>Examples of Path Matching</caption>
 * <thead>
 * <tr><th scope="col">this's path</th><th scope="col">p's path</th><th>match</th></tr>
 * </thead>
 * <tbody style="text-align:left">
 * <tr><th scope="row">/a/b</th><th scope="row">/a/b</th><td>yes</td></tr>
 * <tr><th scope="row" rowspan="3">/a/b/*</th><th scope="row">/a/b/c</th><td>yes</td></tr>
 * <tr> <th scope="row">/a/b/c/d</th><td>no</td></tr>
 * <tr> <th scope="row">/a/b/c/-</th><td>no</td></tr>
 * <tr><th scope="row" rowspan="3">/a/b/-</th><th scope="row">/a/b/c/d</th><td>yes</td></tr>
 * <tr> <th scope="row">/a/b/c/d/e</th><td>yes</td></tr>
 * <tr> <th scope="row">/a/b/c/*</th><td>yes</td></tr>
 * </tbody>
 * </table>
 */
 public boolean implies(Permission p) {
 if (! (p instanceof URLPermission)) {
 return false;
 }

 URLPermission that = (URLPermission)p;

 if (this.methods.isEmpty() && !that.methods.isEmpty()) {
 return false;
 }

 if (!this.methods.isEmpty() &&
 !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 in methods: \"" + methods + "\"");
 } 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 in headers: \"" + headers + "\"");
 } 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: \"" + url + "\"");
 }
 scheme = url.substring(0, delim).toLowerCase();
 this.ssp = url.substring(delim + 1);

 if (!ssp.startsWith("//")) {
 if (!ssp.equals("*")) {
 throw new IllegalArgumentException(
 "Invalid URL string: \"" + url + "\"");
 }
 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() {
 // The colon separator is optional when the request headers list is
 // empty.This implementation chooses to include it even when the request
 // headers list is empty.
 return String.join(",", methods) + ":" + String.join(",", requestHeaders);
 }

 /**
 * 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);
 }
 return false;
 }

 private boolean impliesPortrange(Authority that) {
 int[] thisrange = this.p.portrange();
 int[] thatrange = that.p.portrange();
 if (thisrange[0] == -1) {
 /* port not specified non http/s URL */
 return true;
 }
 return thisrange[0] <= thatrange[0] &&
 thisrange[1] >= thatrange[1];
 }

 boolean equals(Authority that) {
 return this.p.equals(that.p);
 }

 public int hashCode() {
 return p.hashCode();
 }
 }
}