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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,
157 q = (queue *) (*vqueue);
159 if (!q->do_replay && !q->do_sequence)
160 return GSS_S_COMPLETE;
162 /* All checks are done relative to the initial sequence number, to
163 avoid (or at least put off) the pain of wrapping. */
164 seqnum -= q->firstnum;
165 /* If we're only doing 32-bit values, adjust for that again.
167 Note that this will probably be the wrong thing to if we get
168 2**32 messages sent with 32-bit sequence numbers. */
171 /* rule 1: expected sequence number */
173 expected = (QELEM(q,q->start+q->length-1)+1) & q->mask;
174 if (seqnum == expected) {
175 queue_insert(q, q->start+q->length-1, seqnum);
176 return GSS_S_COMPLETE;
179 /* rule 2: > expected sequence number */
181 if ((seqnum > expected)) {
182 queue_insert(q, q->start+q->length-1, seqnum);
183 if (q->do_replay && !q->do_sequence)
184 return GSS_S_COMPLETE;
186 return GSS_S_GAP_TOKEN;
189 /* rule 3: seqnum < seqnum(first) */
191 if ((seqnum < QELEM(q,q->start)) &&
192 /* Is top bit of whatever width we're using set?
194 We used to check for greater than or equal to firstnum, but
195 (1) we've since switched to compute values relative to
196 firstnum, so the lowest we can have is 0, and (2) the effect
197 of the original scheme was highly dependent on whether
198 firstnum was close to either side of 0. (Consider
199 firstnum==0xFFFFFFFE and we miss three packets; the next
200 packet is *new* but would look old.)
202 This check should give us 2**31 or 2**63 messages "new", and
203 just as many "old". That's not quite right either. */
204 (seqnum & (1 + (q->mask >> 1)))
206 if (q->do_replay && !q->do_sequence)
207 return GSS_S_OLD_TOKEN;
209 return GSS_S_UNSEQ_TOKEN;
212 /* rule 4+5: seqnum in [seqnum(first),seqnum(last)] */
215 if (seqnum == QELEM(q,q->start+q->length - 1))
216 return GSS_S_DUPLICATE_TOKEN;
218 for (i = q->start; i < q->start + q->length - 1; i++) {
219 if (seqnum == QELEM(q,i))
220 return GSS_S_DUPLICATE_TOKEN;
221 if ((seqnum > QELEM(q,i)) && (seqnum < QELEM(q,i+1))) {
222 queue_insert(q, i, seqnum);
223 if (q->do_replay && !q->do_sequence)
224 return GSS_S_COMPLETE;
226 return GSS_S_UNSEQ_TOKEN;
231 /* this should never happen */
232 return GSS_S_FAILURE;
236 sequenceFree(OM_uint32 *minor, void **vqueue)
240 q = (queue *) (*vqueue);
247 return GSS_S_COMPLETE;
251 * These support functions are for the serialization routines
254 sequenceSize(void *vqueue GSSEAP_UNUSED)
256 return sizeof(queue);
260 sequenceExternalize(OM_uint32 *minor,
265 if (*lenremain < sizeof(queue)) {
266 *minor = GSSEAP_WRONG_SIZE;
267 return GSS_S_FAILURE;
269 memcpy(*buf, vqueue, sizeof(queue));
270 *buf += sizeof(queue);
271 *lenremain -= sizeof(queue);
277 sequenceInternalize(OM_uint32 *minor,
284 if (*lenremain < sizeof(queue)) {
285 *minor = GSSEAP_TOK_TRUNC;
286 return GSS_S_DEFECTIVE_TOKEN;
289 q = GSSEAP_MALLOC(sizeof(queue));
292 return GSS_S_FAILURE;
295 memcpy(q, *buf, sizeof(queue));
296 *buf += sizeof(queue);
297 *lenremain -= sizeof(queue);
301 return GSS_S_COMPLETE;