source: java/net/deterlab/abac/Role.java @ 3b38c41

abac0-leakabac0-meicompt_changesgec13mei-idmei-rt0-nmei_rt0mei_rt2mei_rt2_fix_1meiyap-rt1meiyap1rt2tvf-new-xml
Last change on this file since 3b38c41 was 3b38c41, checked in by Ted Faber <faber@…>, 13 years ago

Make prereqs visible and role_name work as specced.

  • Property mode set to 100644
File size: 8.0 KB
Line 
1package net.deterlab.abac;
2
3import java.util.*;
4
5import org.bouncycastle.asn1.*;
6
7/**
8 * Represents a role, which is a vertex in a Credential graph.
9 * @author <a href="http://abac.deterlab.net">ISI ABAC team</a>
10 * @version 1.3
11 */
12public class Role implements Comparable {
13    /** The role represnetation */
14    protected String m_string;
15    /** The role broken into parts between dots */
16    protected String[] m_parts;
17    /** The linking role from a linking Role */
18    protected String m_A_r1;
19    /** The linked role from a linked Role */
20    protected String m_r2;
21    /** A prefix of the role */
22    protected String m_prefix;
23    /** Prerequisite roles for an intersection role. */
24    protected Role[] m_prereqs;
25
26    /**
27     * Create a role from a string. A single role must be of the format "A",
28     * "A.r1", or "A.r1.r2", where A is a principal and r1 and r2 are role
29     * names. This constructor also supports intersection roles: a sequence of
30     * two or more roles separated by "&amp;". The whitespace surrounding &amp;
31     * is arbitrary.
32     *
33     * If the string does not have this format, the constructor throws a
34     * RuntimeException.
35     *
36     * @param s a String with the role name
37     * @throws RuntimeException if the string is badly formatted
38     */
39    public Role(String s) {
40        m_string = s;
41
42        // intersection roles have at least two roles separated by "&"
43        String[] isect_roles = s.split("&");
44
45        // ordinary role
46        if (isect_roles.length == 1)
47            single_role();
48
49        // intersection role: make a list of prereqs
50        else {
51            m_prereqs = new Role[isect_roles.length];
52
53            // trim() handles arbitrary whitespace
54            for (int i = 0; i < isect_roles.length; ++i)
55                m_prereqs[i] = new Role(isect_roles[i].trim());
56
57            // this make is_principal etc. work properly
58            m_parts = new String[0];
59        }
60    }
61
62    /**
63     * Create a role from the given string, converted from mnemonic strings to
64     * key IDs that are known from the Context.  This is a jabac extension.
65     * @param s the String containing the rile name.
66     * @param c the Context in which to expand mnemonics
67     * @throws RuntimeException if the string is badly formatted.
68     */
69    public Role(String s, Context c) {
70        this(c.expandKeyID(s));
71    }
72
73    /**
74     * Copy an existing role.
75     * @param r the Role to copy
76     */
77    public Role(Role r) {
78        m_string = r.m_string;
79        m_A_r1 = r.m_A_r1;
80        m_r2 = r.m_r2;
81        m_prefix = r.m_prefix;
82        m_parts = new String[r.m_parts.length];
83        for (int i = 0; i < r.m_parts.length; i++) 
84            m_parts[i] = r.m_parts[i];
85        m_prereqs = new Role[m_prereqs.length];
86        for (int i = 0; i < r.m_prereqs.length; i++) 
87            m_prereqs[i] = new Role(r.m_prereqs[i]);
88    }
89
90    /**
91     * Initialize a single non-intersection role. See constructor for details
92     * of role format. Will throw RuntimeException if the role is invalid.
93     * @throws RuntimeException if a role is invalid.
94     */
95    private void single_role() {
96        m_parts = m_string.split("\\.");
97        if (m_parts.length > 3)
98            throw new RuntimeException("Not a valid role: " + m_string);
99
100        // linking role: prefix is A.r1 from A.r1.r2
101        if (is_linking()) {
102            m_A_r1 = m_parts[0] + "." + m_parts[1];
103            m_r2 = m_parts[2];
104            m_prefix = m_A_r1;
105        }
106
107        // role: prefix is A from A.r1
108        else if (is_role())
109            m_prefix = m_parts[0];
110
111        // principal: prefix is the whole thing
112        else
113            m_prefix = m_string;
114    }
115
116    /**
117     * Returns true iff the role is a principal.
118     * @return true iff the role is a principal.
119     */
120    public boolean is_principal() { return m_parts.length == 1; }
121
122    /**
123     * Returns true iff the role is a role (i.e., A.r1).
124     * @return true iff the role is a role (i.e., A.r1).
125     */
126    public boolean is_role() { return m_parts.length == 2; }
127
128    /**
129     * Returns true iff the role is a linking role (i.e., A.r1.r2).
130     * @return true iff the role is a linking role (i.e., A.r1.r2).
131     */
132    public boolean is_linking() { return m_parts.length == 3; }
133
134    /**
135     * Returns true iff the role represents an intersection role.
136     * @return true iff the role represents an intersection role.
137     */
138    public boolean is_intersection() { return m_prereqs != null; }
139
140    /**
141     * Returns the first two elements of a linking role's name. This typically
142     * refers to another role in the graph. This will throw a runtime
143     * exception if the node is not a linking role.
144     * @return the first two elements of a linking role's name.
145     * @throws RuntimeException if the role is not linking
146     */
147    String A_r1() throws RuntimeException {
148        if (!is_linking())
149            throw new RuntimeException("Not a linking role");
150        return m_A_r1;
151    }
152
153    /**
154     * Return the last element of a linking role's name. This will throw a
155     * runtime exception if the node is not a linking role.
156     * @return the last element of a linking role's name.
157     * @throws RuntimeException if the node is not a linking role.
158     */
159    String r2() throws RuntimeException {
160        if (!is_linking())
161            throw new RuntimeException("Not a linking role");
162        return m_r2;
163    }
164
165    /**
166     * Returns the principal part of a role or principal. This is everything
167     * except the last element of the name.  Used by Query.
168     * @return the principal part of a role or principal.
169     */
170    String principal_part() {
171        return m_prefix;
172    }
173
174    /**
175     * Return the principal
176     * @return the principal
177     */
178    public String principal() { return m_parts.length > 0 ? m_parts[0] : null; }
179    /**
180     * Return the role name after the last dot
181     * @return the role name
182     */
183    public String role_name() { return m_parts[m_parts.length-1]; }
184    /**
185     * Return the linked role (first two parts of a linking role)
186     * @return the linked role
187     */
188    public String linked_role() { return A_r1(); }
189
190    /**
191     * Get the roles that form the prerequisites to this intersection. Throws
192     * a runtime exception if this is not an intersection role.
193     * @return a Role[] of prerequisites
194     * @throws RuntimeException if this is not an intersection role
195     */
196    public Role[] prereqs() throws RuntimeException {
197        if (!is_intersection())
198            throw new RuntimeException("Not an intersection role.");
199
200        return m_prereqs;
201    }
202
203    /**
204     * Returns a string representation of the Role.
205     * @return a string representation of the Role.
206     */
207    public String toString() {
208        return m_string;
209    }
210
211    /**
212     * Returns a string representation of the Role with mnemonic names from the
213     * given Context.  A jabac extension.
214     * @param c A Context used to look up mnemonic names.
215     * @return a string representation of the Role with mnemonic names from the
216     * given Context.
217     */
218    public String simpleString(Context c) {
219        return c.expandNickname(m_string);
220    }
221
222    /**
223     * Equality test.  Two Roles are the same if their string representations
224     * are equal.
225     * @param v2 an Object to compare
226     * @return a boolean, true if the two Roles are equal.
227     */
228    public boolean equals(Object v2) {
229        if (v2 instanceof Role)
230            return m_string.equals(((Role)v2).m_string);
231        return false;
232    }
233
234    /**
235     * Partial order test.  Return a lexical comparison of the two Roles
236     * @param o an Object to compare against
237     * @return -1 if this Role is before, 0 if they are the same, and 1
238     *              if this Role is after the given object.
239     */
240    public int compareTo(Object o) {
241        if (o instanceof Role) 
242            return m_string.compareTo(((Role)o).m_string);
243        else return 1;
244    }
245
246    /**
247     * Returns a hash code value for the object.  It is the hash of the string
248     * representation.
249     * @return a hash code value for the object.
250     */
251    public int hashCode() {
252        return m_string.hashCode();
253    }
254
255}
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