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55 * $Id: util_ordering.c 23457 2009-12-08 00:04:48Z tlyu $
59 * functions to check sequence numbers for replay and sequencing
62 #include "gssapiP_eap.h"
64 #define QUEUE_LENGTH 20
66 typedef struct _queue {
72 /* Stored as deltas from firstnum. This way, the high bit won't
73 overflow unless we've actually gone through 2**n messages, or
74 gotten something *way* out of sequence. */
75 uint64_t elem[QUEUE_LENGTH];
76 /* All ones for 64-bit sequence numbers; 32 ones for 32-bit
82 * - the queue is a circular queue. The first element (q->elem[q->start])
83 * is the oldest. The last element is the newest.
86 #define QSIZE(q) (sizeof((q)->elem)/sizeof((q)->elem[0]))
87 #define QELEM(q,i) ((q)->elem[(i)%QSIZE(q)])
90 queue_insert(queue *q, int after, uint64_t seqnum)
92 /* insert. this is not the fastest way, but it's easy, and it's
93 optimized for insert at end, which is the common case */
96 /* common case: at end, after == q->start+q->length-1 */
98 /* move all the elements (after,last] up one slot */
100 for (i = q->start + q->length - 1; i > after; i--)
101 QELEM(q,i+1) = QELEM(q,i);
103 /* fill in slot after+1 */
105 QELEM(q,after+1) = seqnum;
107 /* Either increase the length by one, or move the starting point up
108 one (deleting the first element, which got bashed above), as
111 if (q->length == QSIZE(q)) {
113 if (q->start == QSIZE(q))
121 sequenceInit(OM_uint32 *minor,
130 q = (queue *)GSSEAP_CALLOC(1, sizeof(queue));
133 return GSS_S_FAILURE;
136 q->do_replay = do_replay;
137 q->do_sequence = do_sequence;
138 q->mask = wide_nums ? ~(uint64_t)0 : 0xffffffffUL;
142 q->firstnum = seqnum;
143 q->elem[q->start] = ((uint64_t)0 - 1) & q->mask;
147 return GSS_S_COMPLETE;
151 sequenceCheck(OM_uint32 *minor,
159 q = (queue *) (*vqueue);
161 if (!q->do_replay && !q->do_sequence)
162 return GSS_S_COMPLETE;
164 /* All checks are done relative to the initial sequence number, to
165 avoid (or at least put off) the pain of wrapping. */
166 seqnum -= q->firstnum;
167 /* If we're only doing 32-bit values, adjust for that again.
169 Note that this will probably be the wrong thing to if we get
170 2**32 messages sent with 32-bit sequence numbers. */
173 /* rule 1: expected sequence number */
175 expected = (QELEM(q,q->start+q->length-1)+1) & q->mask;
176 if (seqnum == expected) {
177 queue_insert(q, q->start+q->length-1, seqnum);
178 return GSS_S_COMPLETE;
181 /* rule 2: > expected sequence number */
183 if ((seqnum > expected)) {
184 queue_insert(q, q->start+q->length-1, seqnum);
185 if (q->do_replay && !q->do_sequence)
186 return GSS_S_COMPLETE;
188 return GSS_S_GAP_TOKEN;
191 /* rule 3: seqnum < seqnum(first) */
193 if ((seqnum < QELEM(q,q->start)) &&
194 /* Is top bit of whatever width we're using set?
196 We used to check for greater than or equal to firstnum, but
197 (1) we've since switched to compute values relative to
198 firstnum, so the lowest we can have is 0, and (2) the effect
199 of the original scheme was highly dependent on whether
200 firstnum was close to either side of 0. (Consider
201 firstnum==0xFFFFFFFE and we miss three packets; the next
202 packet is *new* but would look old.)
204 This check should give us 2**31 or 2**63 messages "new", and
205 just as many "old". That's not quite right either. */
206 (seqnum & (1 + (q->mask >> 1)))
208 if (q->do_replay && !q->do_sequence)
209 return GSS_S_OLD_TOKEN;
211 return GSS_S_UNSEQ_TOKEN;
214 /* rule 4+5: seqnum in [seqnum(first),seqnum(last)] */
217 if (seqnum == QELEM(q,q->start+q->length - 1))
218 return GSS_S_DUPLICATE_TOKEN;
220 for (i = q->start; i < q->start + q->length - 1; i++) {
221 if (seqnum == QELEM(q,i))
222 return GSS_S_DUPLICATE_TOKEN;
223 if ((seqnum > QELEM(q,i)) && (seqnum < QELEM(q,i+1))) {
224 queue_insert(q, i, seqnum);
225 if (q->do_replay && !q->do_sequence)
226 return GSS_S_COMPLETE;
228 return GSS_S_UNSEQ_TOKEN;
233 /* this should never happen */
234 return GSS_S_FAILURE;
238 sequenceFree(OM_uint32 *minor, void **vqueue)
242 q = (queue *) (*vqueue);
248 return GSS_S_COMPLETE;
252 * These support functions are for the serialization routines
255 sequenceSize(void *vqueue)
257 return sizeof(queue);
261 sequenceExternalize(OM_uint32 *minor,
266 if (*lenremain < sizeof(queue)) {
268 return GSS_S_FAILURE;
270 memcpy(*buf, vqueue, sizeof(queue));
271 *buf += sizeof(queue);
272 *lenremain -= sizeof(queue);
278 sequenceInternalize(OM_uint32 *minor,
285 if (*lenremain < sizeof(queue)) {
287 return GSS_S_DEFECTIVE_TOKEN;
290 q = GSSEAP_MALLOC(sizeof(queue));
293 return GSS_S_FAILURE;
296 memcpy(q, *buf, sizeof(queue));
297 *buf += sizeof(queue);
298 *lenremain -= sizeof(queue);
302 return GSS_S_COMPLETE;