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25 
26 package sun.security.util;
27 
28 import java.security.AccessController;
29 import java.security.AlgorithmConstraints;
30 import java.security.PrivilegedAction;
31 import java.security.Security;
32 import java.util.Set;
33 
34 /**
35  * The class contains common functionality for algorithm constraints classes.
36  */
37 public abstract class AbstractAlgorithmConstraints
38         implements AlgorithmConstraints {
39 
40     protected final AlgorithmDecomposer decomposer;
41 
AbstractAlgorithmConstraints(AlgorithmDecomposer decomposer)42     protected AbstractAlgorithmConstraints(AlgorithmDecomposer decomposer) {
43         this.decomposer = decomposer;
44     }
45 
46     // Get algorithm constraints from the specified security property.
getAlgorithms(String propertyName)47     static String[] getAlgorithms(String propertyName) {
48         String property = AccessController.doPrivileged(
49                 new PrivilegedAction<String>() {
50                     @Override
51                     public String run() {
52                         return Security.getProperty(propertyName);
53                     }
54                 });
55 
56 
57         String[] algorithmsInProperty = null;
58         if (property != null && !property.isEmpty()) {
59             // remove double quote marks from beginning/end of the property
60             if (property.length() >= 2 && property.charAt(0) == '"' &&
61                     property.charAt(property.length() - 1) == '"') {
62                 property = property.substring(1, property.length() - 1);
63             }
64             algorithmsInProperty = property.split(",");
65             for (int i = 0; i < algorithmsInProperty.length; i++) {
66                 algorithmsInProperty[i] = algorithmsInProperty[i].trim();
67             }
68         }
69 
70         // map the disabled algorithms
71         if (algorithmsInProperty == null) {
72             algorithmsInProperty = new String[0];
73         }
74         return algorithmsInProperty;
75     }
76 
checkAlgorithm(String[] algorithms, String algorithm, AlgorithmDecomposer decomposer)77     static boolean checkAlgorithm(String[] algorithms, String algorithm,
78             AlgorithmDecomposer decomposer) {
79         if (algorithm == null || algorithm.length() == 0) {
80             throw new IllegalArgumentException("No algorithm name specified");
81         }
82 
83         Set<String> elements = null;
84         for (String item : algorithms) {
85             if (item == null || item.isEmpty()) {
86                 continue;
87             }
88 
89             // check the full name
90             if (item.equalsIgnoreCase(algorithm)) {
91                 return false;
92             }
93 
94             // decompose the algorithm into sub-elements
95             if (elements == null) {
96                 elements = decomposer.decompose(algorithm);
97             }
98 
99             // check the items of the algorithm
100             for (String element : elements) {
101                 if (item.equalsIgnoreCase(element)) {
102                     return false;
103                 }
104             }
105         }
106 
107         return true;
108     }
109 
110 }
111