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55 * Functions to check sequence numbers for replay and sequencing
58 #include "gssapiP_eap.h"
60 #define QUEUE_LENGTH 20
62 typedef struct _queue {
68 /* Stored as deltas from firstnum. This way, the high bit won't
69 overflow unless we've actually gone through 2**n messages, or
70 gotten something *way* out of sequence. */
71 uint64_t elem[QUEUE_LENGTH];
72 /* All ones for 64-bit sequence numbers; 32 ones for 32-bit
78 * - the queue is a circular queue. The first element (q->elem[q->start])
79 * is the oldest. The last element is the newest.
82 #define QSIZE(q) (sizeof((q)->elem)/sizeof((q)->elem[0]))
83 #define QELEM(q,i) ((q)->elem[(i)%QSIZE(q)])
86 queue_insert(queue *q, int after, uint64_t seqnum)
88 /* insert. this is not the fastest way, but it's easy, and it's
89 optimized for insert at end, which is the common case */
92 /* common case: at end, after == q->start+q->length-1 */
94 /* move all the elements (after,last] up one slot */
96 for (i = q->start + q->length - 1; i > after; i--)
97 QELEM(q,i+1) = QELEM(q,i);
99 /* fill in slot after+1 */
101 QELEM(q,after+1) = seqnum;
103 /* Either increase the length by one, or move the starting point up
104 one (deleting the first element, which got bashed above), as
107 if (q->length == QSIZE(q)) {
109 if (q->start == QSIZE(q))
117 sequenceInit(OM_uint32 *minor,
126 q = (queue *)GSSEAP_CALLOC(1, sizeof(queue));
129 return GSS_S_FAILURE;
132 q->do_replay = do_replay;
133 q->do_sequence = do_sequence;
134 q->mask = wide_nums ? ~(uint64_t)0 : 0xffffffffUL;
138 q->firstnum = seqnum;
139 q->elem[q->start] = ((uint64_t)0 - 1) & q->mask;
143 return GSS_S_COMPLETE;
147 sequenceCheck(OM_uint32 *minor,
155 q = (queue *) (*vqueue);
157 if (!q->do_replay && !q->do_sequence)
158 return GSS_S_COMPLETE;
160 /* All checks are done relative to the initial sequence number, to
161 avoid (or at least put off) the pain of wrapping. */
162 seqnum -= q->firstnum;
163 /* If we're only doing 32-bit values, adjust for that again.
165 Note that this will probably be the wrong thing to if we get
166 2**32 messages sent with 32-bit sequence numbers. */
169 /* rule 1: expected sequence number */
171 expected = (QELEM(q,q->start+q->length-1)+1) & q->mask;
172 if (seqnum == expected) {
173 queue_insert(q, q->start+q->length-1, seqnum);
174 return GSS_S_COMPLETE;
177 /* rule 2: > expected sequence number */
179 if ((seqnum > expected)) {
180 queue_insert(q, q->start+q->length-1, seqnum);
181 if (q->do_replay && !q->do_sequence)
182 return GSS_S_COMPLETE;
184 return GSS_S_GAP_TOKEN;
187 /* rule 3: seqnum < seqnum(first) */
189 if ((seqnum < QELEM(q,q->start)) &&
190 /* Is top bit of whatever width we're using set?
192 We used to check for greater than or equal to firstnum, but
193 (1) we've since switched to compute values relative to
194 firstnum, so the lowest we can have is 0, and (2) the effect
195 of the original scheme was highly dependent on whether
196 firstnum was close to either side of 0. (Consider
197 firstnum==0xFFFFFFFE and we miss three packets; the next
198 packet is *new* but would look old.)
200 This check should give us 2**31 or 2**63 messages "new", and
201 just as many "old". That's not quite right either. */
202 (seqnum & (1 + (q->mask >> 1)))
204 if (q->do_replay && !q->do_sequence)
205 return GSS_S_OLD_TOKEN;
207 return GSS_S_UNSEQ_TOKEN;
210 /* rule 4+5: seqnum in [seqnum(first),seqnum(last)] */
213 if (seqnum == QELEM(q,q->start+q->length - 1))
214 return GSS_S_DUPLICATE_TOKEN;
216 for (i = q->start; i < q->start + q->length - 1; i++) {
217 if (seqnum == QELEM(q,i))
218 return GSS_S_DUPLICATE_TOKEN;
219 if ((seqnum > QELEM(q,i)) && (seqnum < QELEM(q,i+1))) {
220 queue_insert(q, i, seqnum);
221 if (q->do_replay && !q->do_sequence)
222 return GSS_S_COMPLETE;
224 return GSS_S_UNSEQ_TOKEN;
229 /* this should never happen */
230 return GSS_S_FAILURE;
234 sequenceFree(OM_uint32 *minor, void **vqueue)
238 q = (queue *) (*vqueue);
244 return GSS_S_COMPLETE;
248 * These support functions are for the serialization routines
251 sequenceSize(void *vqueue)
253 return sizeof(queue);
257 sequenceExternalize(OM_uint32 *minor,
262 if (*lenremain < sizeof(queue)) {
263 *minor = GSSEAP_WRONG_SIZE;
264 return GSS_S_FAILURE;
266 memcpy(*buf, vqueue, sizeof(queue));
267 *buf += sizeof(queue);
268 *lenremain -= sizeof(queue);
274 sequenceInternalize(OM_uint32 *minor,
281 if (*lenremain < sizeof(queue)) {
282 *minor = GSSEAP_TOK_TRUNC;
283 return GSS_S_DEFECTIVE_TOKEN;
286 q = GSSEAP_MALLOC(sizeof(queue));
289 return GSS_S_FAILURE;
292 memcpy(q, *buf, sizeof(queue));
293 *buf += sizeof(queue);
294 *lenremain -= sizeof(queue);
298 return GSS_S_COMPLETE;