1 /*
2  * Copyright (c) 1998, 2019, Oracle and/or its affiliates. All rights reserved.
3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4  *
5  * This code is free software; you can redistribute it and/or modify it
6  * under the terms of the GNU General Public License version 2 only, as
7  * published by the Free Software Foundation.  Oracle designates this
8  * particular file as subject to the "Classpath" exception as provided
9  * by Oracle in the LICENSE file that accompanied this code.
10  *
11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
16  *
17  * You should have received a copy of the GNU General Public License version
18  * 2 along with this work; if not, write to the Free Software Foundation,
19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20  *
21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22  * or visit www.oracle.com if you need additional information or have any
23  * questions.
24  */
25 
26 package sun.security.util;
27 
28 import java.net.URI;
29 import java.net.URISyntaxException;
30 import java.security.GeneralSecurityException;
31 
32 /**
33  * A utility class to expand properties embedded in a string.
34  * Strings of the form ${some.property.name} are expanded to
35  * be the value of the property. Also, the special ${/} property
36  * is expanded to be the same as file.separator. If a property
37  * is not set, a GeneralSecurityException will be thrown.
38  *
39  * @author Roland Schemers
40  */
41 public class PropertyExpander {
42 
43 
44     public static class ExpandException extends GeneralSecurityException {
45 
46         @java.io.Serial
47         private static final long serialVersionUID = -7941948581406161702L;
48 
ExpandException(String msg)49         public ExpandException(String msg) {
50             super(msg);
51         }
52     }
53 
expand(String value)54     public static String expand(String value)
55         throws ExpandException
56     {
57         return expand(value, false);
58     }
59 
expand(String value, boolean encodeURL)60      public static String expand(String value, boolean encodeURL)
61          throws ExpandException
62      {
63         if (value == null)
64             return null;
65 
66         int p = value.indexOf("${", 0);
67 
68         // no special characters
69         if (p == -1) return value;
70 
71         StringBuilder sb = new StringBuilder(value.length());
72         int max = value.length();
73         int i = 0;  // index of last character we copied
74 
75     scanner:
76         while (p < max) {
77             if (p > i) {
78                 // copy in anything before the special stuff
79                 sb.append(value.substring(i, p));
80                 i = p;
81             }
82             int pe = p+2;
83 
84             // do not expand ${{ ... }}
85             if (pe < max && value.charAt(pe) == '{') {
86                 pe = value.indexOf("}}", pe);
87                 if (pe == -1 || pe+2 == max) {
88                     // append remaining chars
89                     sb.append(value.substring(p));
90                     break scanner;
91                 } else {
92                     // append as normal text
93                     pe++;
94                     sb.append(value.substring(p, pe+1));
95                 }
96             } else {
97                 while ((pe < max) && (value.charAt(pe) != '}')) {
98                     pe++;
99                 }
100                 if (pe == max) {
101                     // no matching '}' found, just add in as normal text
102                     sb.append(value.substring(p, pe));
103                     break scanner;
104                 }
105                 String prop = value.substring(p+2, pe);
106                 if (prop.equals("/")) {
107                     sb.append(java.io.File.separatorChar);
108                 } else {
109                     String val = System.getProperty(prop);
110                     if (val != null) {
111                         if (encodeURL) {
112                             // encode 'val' unless it's an absolute URI
113                             // at the beginning of the string buffer
114                             try {
115                                 if (sb.length() > 0 ||
116                                     !(new URI(val)).isAbsolute()) {
117                                     val = sun.net.www.ParseUtil.encodePath(val);
118                                 }
119                             } catch (URISyntaxException use) {
120                                 val = sun.net.www.ParseUtil.encodePath(val);
121                             }
122                         }
123                         sb.append(val);
124                     } else {
125                         throw new ExpandException(
126                                              "unable to expand property " +
127                                              prop);
128                     }
129                 }
130             }
131             i = pe+1;
132             p = value.indexOf("${", i);
133             if (p == -1) {
134                 // no more to expand. copy in any extra
135                 if (i < max) {
136                     sb.append(value.substring(i, max));
137                 }
138                 // break out of loop
139                 break scanner;
140             }
141         }
142         return sb.toString();
143     }
144 }
145