[8552] in bugtraq
Re: NT DNS hacked ... ?
daemon@ATHENA.MIT.EDU (Don Lewis)
Sat Nov 14 15:56:45 1998
Date: Fri, 13 Nov 1998 16:25:38 -0800
Reply-To: Don Lewis <Don.Lewis@TSC.TDK.COM>
From: Don Lewis <Don.Lewis@TSC.TDK.COM>
X-To: bobk <bobk@SINISTER.COM>
To: BUGTRAQ@NETSPACE.ORG
In-Reply-To: bobk <bobk@SINISTER.COM> "Re: NT DNS hacked ... ?" (Nov 13,
6:24pm)
On Nov 13, 6:24pm, bobk wrote:
} Subject: Re: NT DNS hacked ... ?
} "cache corruption through sequence ID prediction" is a more complex
} attack. Both Microsoft and BIND are vulnerable to this. Luckily, there
} aren't many crackers attempting to use this, as far as I can tell. There
} is no complete protection for this attack, even though vendors of DNS
} software have known about the vulnerability for years.
Here is a patch for this that I'm using with a version of BIND slightly
older than 8.1.2. It applies cleanly to 8.1.2 and compiles ...
Index: named.h
===================================================================
RCS file: /proj/named/BIND8/src/bin/named/named.h,v
retrieving revision 1.1.1.2
retrieving revision 1.2
diff -u -r1.1.1.2 -r1.2
--- named.h 1997/12/11 11:26:37 1.1.1.2
+++ named.h 1998/01/21 11:32:42 1.2
@@ -41,6 +41,7 @@
#define ROUND_ROBIN
#define SORT_RESPONSE
#define DNS_SECURITY
+#define RANDOMIZE_ID
#undef RSAREF
#undef BSAFE
#define ALLOW_LONG_TXT_RDATA
Index: ns_config.c
===================================================================
RCS file: /proj/named/BIND8/src/bin/named/ns_config.c,v
retrieving revision 1.1.1.2
retrieving revision 1.4
diff -u -r1.1.1.2 -r1.4
--- ns_config.c 1997/12/11 11:26:39 1.1.1.2
+++ ns_config.c 1998/01/21 11:32:43 1.4
@@ -876,6 +885,9 @@
case OPTION_MULTIPLE_CNAMES:
case OPTION_HOSTSTATS:
case OPTION_DEALLOC_ON_EXIT:
+#ifdef RANDOMIZE_ID
+ case OPTION_USE_ID_POOL:
+#endif /* RANDOMIZE_ID */
if (value)
op->flags |= bool_opt;
else
Index: ns_defs.h
===================================================================
RCS file: /proj/named/BIND8/src/bin/named/ns_defs.h,v
retrieving revision 1.1.1.2
retrieving revision 1.3
diff -u -r1.1.1.2 -r1.3
--- ns_defs.h 1997/12/11 11:26:41 1.1.1.2
+++ ns_defs.h 1998/01/21 11:32:45 1.3
@@ -144,6 +144,10 @@
* CNAME RRs */
#define OPTION_HOSTSTATS 0x0080 /* Maintain per-host statistics? */
#define OPTION_DEALLOC_ON_EXIT 0x0100 /* Deallocate everything on exit? */
+#ifdef RANDOMIZE_ID
+#define OPTION_USE_ID_POOL 0x0200 /* Use the memory hogging query ID
+ * pool */
+#endif /* RANDOMIZE_ID */
#define DEFAULT_OPTION_FLAGS (OPTION_HOSTSTATS)
Index: ns_func.h
===================================================================
RCS file: /proj/named/BIND8/src/bin/named/ns_func.h,v
retrieving revision 1.1.1.2
retrieving revision 1.4
diff -u -r1.1.1.2 -r1.4
--- ns_func.h 1997/12/11 11:26:45 1.1.1.2
+++ ns_func.h 1998/01/21 11:32:48 1.4
@@ -212,6 +212,9 @@
writestream(struct qstream *, const u_char *, int),
ns_need(int need),
opensocket_f(void);
+#ifdef RANDOMIZE_ID
+extern void nsid_hash(u_char *, size_t);
+#endif /* RANDOMIZE_ID */
extern u_int16_t nsid_next(void);
extern int sq_openw(struct qstream *, int),
sq_writeh(struct qstream *, sq_closure),
Index: ns_lexer.c
===================================================================
RCS file: /proj/named/BIND8/src/bin/named/ns_lexer.c,v
retrieving revision 1.1.1.2
retrieving revision 1.3
diff -u -r1.1.1.2 -r1.3
--- ns_lexer.c 1997/12/11 11:26:52 1.1.1.2
+++ ns_lexer.c 1998/01/21 11:32:49 1.3
@@ -295,6 +298,9 @@
{"true", T_TRUE},
{"type", T_TYPE},
{"unlimited", T_UNLIMITED},
+#ifdef RANDOMIZE_ID
+ {"use-id-pool", T_USE_ID_POOL},
+#endif /* RANDOMIZE_ID */
{"versions", T_VERSIONS},
{"warn", T_WARN},
{"yes", T_YES},
Index: ns_main.c
===================================================================
RCS file: /proj/named/BIND8/src/bin/named/ns_main.c,v
retrieving revision 1.1.1.2
retrieving revision 1.4
diff -u -r1.1.1.2 -r1.4
--- ns_main.c 1997/12/11 11:26:53 1.1.1.2
+++ ns_main.c 1998/01/21 11:32:50 1.4
@@ -143,6 +143,16 @@
sbufsize = 16 * 1024;
static u_int16_t nsid_state;
+#ifdef RANDOMIZE_ID
+static u_int16_t *nsid_pool; /* optional query id pool */
+static u_int16_t *nsid_vtable; /* optional shuffle table */
+static u_int32_t nsid_hash_state;
+static u_int16_t nsid_a1, nsid_a2, nsid_a3;
+static u_int16_t nsid_c1, nsid_c2, nsid_c3;
+static u_int16_t nsid_state2;
+static int nsid_algorithm;
+#endif /* RANDOMIZE_ID */
+
static int needs;
static struct qstream *sq_add(void);
@@ -331,8 +341,6 @@
_res.options &= ~(RES_DEFNAMES | RES_DNSRCH | RES_RECURSE);
- nsid_init();
-
/*
* Initialize and load database.
*/
@@ -343,6 +351,8 @@
time(&boottime);
resettime = boottime;
+ nsid_init();
+
/*
* Fork and go into background now that
* we've done any slow initialization
@@ -1800,8 +1808,401 @@
* allocation scheme to make it a little harder to predict them. Note
* that the resolver will need the same protection so the cleverness
* should be put there rather than here; this is just an interface layer.
+ *
+ * This is true but ... most clients only send out a few queries, they
+ * use varying port numbers, and the queries aren't sent to the outside
+ * world which we know is full of spoofers. Doing a good job of randomizing
+ * ids may also be to expensive for each client. Queries forwarded by the
+ * server always come from the same port (unless you let 8.x pick a port
+ * and restart it periodically - maybe it should open several and use
+ * them randomly). The server sends out lots more queries, and if it's
+ * cache is corrupted, it has the potential to affect more clients.
+ * NOTE: - randomizing the ID or source port doesn't help a bit if the
+ * queries can be sniffed.
+ * -- DL
+ */
+
+#ifdef RANDOMIZE_ID
+/*
+ * Allow the user to pick one of two ID randomization algorithms.
+ *
+ * The first algorithm is an adaptation of the sequence shuffling
+ * algorithm discovered by Carter Bays and S. D. Durham [ACM Trans. Math.
+ * Software 2 (1976), 59-64], as documented as Algorithm B in Chapter
+ * 3.2.2 in Volume 2 of Knuth's "The Art of Computer Programming". We use
+ * a randomly selected linear congruential random number generator with a
+ * modulus of 2^16, whose increment is a randomly picked odd number, and
+ * whose multiplier is picked from a set which meets the following
+ * criteria:
+ * Is of the form 8*n+5, which ensures "high potency" according to
+ * principle iii in the summary chapter 3.6. This form also has a
+ * gcd(a-1,m) of 4 which is good according to principle iv.
+ *
+ * Is between 0.01 and 0.99 times the modulus as specified by
+ * principle iv.
+ *
+ * Passes the spectral test "with flying colors" (ut >= 1) in
+ * dimensions 2 through 6 as calculated by Algorithm S in Chapter
+ * 3.3.4 and the ratings calculated by formula 35 in section E.
+ *
+ * Of the multipliers that pass this test, pick the set that is
+ * best according to the theoretical bounds of the serial
+ * correlation test. This was calculated using a simplified
+ * version of Knuth's Theorem K in Chapter 3.3.3.
+ *
+ * These criteria may not be important for this use, but we might as well
+ * pick from the best generators since there are so many possible ones and
+ * we don't have that many random bits to do the picking.
+ *
+ * We use a modulus of 2^16 instead of something bigger so that we will
+ * tend to cycle through all the possible IDs before repeating any,
+ * however the shuffling will perturb this somewhat. Theoretically there
+ * is no minimimum interval between two uses of the same ID, but in
+ * practice it seems to be >64000.
+ *
+ * Our adaptatation of Algorithm B mixes the hash state which has
+ * captured various random events into the shuffler to perturb the
+ * sequence.
+ *
+ * One disadvantage of this algorithm is that if the generator parameters
+ * were to be guessed, it would be possible to mount a limited brute force
+ * attack on the ID space since the IDs are only shuffled within a limited
+ * range.
+ *
+ * The second algorithm uses the same random number generator to populate
+ * a pool of 65536 IDs. The hash state is used to pick an ID from a window
+ * of 4096 IDs in this pool, then the chosen ID is swapped with the ID
+ * at the beginning of the window and the window position is advanced.
+ * This means that the interval between uses of the ID will be no less
+ * than 65536-4096. The ID sequence in the pool will become more random
+ * over time.
+ *
+ * For both algorithms, two more linear congruential random number generators
+ * are selected. The ID from the first part of algorithm is used to seed
+ * the first of these generators, and its output is used to seed the second.
+ * The strategy is use these generators as 1 to 1 hashes to obfuscate the
+ * properties of the generator used in the first part of either algorithm.
+ *
+ * The first algorithm may be suitable for use in a client resolver since
+ * its memory requirements are fairly low and it's pretty random out of
+ * the box. It is somewhat succeptible to a limited brute force attack,
+ * so the second algorithm is probably preferable for a longer running
+ * program that issues a large number of queries and has time to randomize
+ * the pool.
+ */
+
+#define NSID_SHUFFLE_TABLE_SIZE 100 /* Suggested by Knuth */
+/*
+ * Pick one of the next 4096 IDs in the pool.
+ * There is a tradeoff here between randomness and how often and ID is reused.
+ */
+#define NSID_LOOKAHEAD 4096 /* Must be a power of 2 */
+#define NSID_SHUFFLE_ONLY 1 /* algorithm 1 */
+#define NSID_USE_POOL 2 /* algorithm 2 */
+
+/*
+ * Keep a running hash of various bits of data that we'll use to
+ * stir the ID pool or perturb the ID generator
*/
+void
+nsid_hash(u_char *data, size_t len) {
+ /*
+ * Hash function similar to the one we use for hashing names.
+ * We don't fold case or toss the upper bit here, though.
+ * This hash doesn't do much interesting when fed binary zeros,
+ * so there may be a better hash function.
+ * This function doesn't need to be very strong since we're
+ * only using it to stir the pool, but it should be reasonably
+ * fast.
+ */
+ while (len-- > 0) {
+ /* rotate left HASHSHIFT */
+ nsid_hash_state = (nsid_hash_state << HASHSHIFT) |
+ (nsid_hash_state>>((sizeof(nsid_hash_state)*8)-HASHSHIFT));
+ nsid_hash_state += *data++;
+ }
+}
+
+/*
+ * Table of good linear congruential multipliers for modulus 2^16
+ * in order of increasing serial correlation bounds (so trim from
+ * the end).
+ */
+static const u_int16_t nsid_multiplier_table[] = {
+ 17565, 25013, 11733, 19877, 23989, 23997, 24997, 25421,
+ 26781, 27413, 35901, 35917, 35973, 36229, 38317, 38437,
+ 39941, 40493, 41853, 46317, 50581, 51429, 53453, 53805,
+ 11317, 11789, 12045, 12413, 14277, 14821, 14917, 18989,
+ 19821, 23005, 23533, 23573, 23693, 27549, 27709, 28461,
+ 29365, 35605, 37693, 37757, 38309, 41285, 45261, 47061,
+ 47269, 48133, 48597, 50277, 50717, 50757, 50805, 51341,
+ 51413, 51581, 51597, 53445, 11493, 14229, 20365, 20653,
+ 23485, 25541, 27429, 29421, 30173, 35445, 35653, 36789,
+ 36797, 37109, 37157, 37669, 38661, 39773, 40397, 41837,
+ 41877, 45293, 47277, 47845, 49853, 51085, 51349, 54085,
+ 56933, 8877, 8973, 9885, 11365, 11813, 13581, 13589,
+ 13613, 14109, 14317, 15765, 15789, 16925, 17069, 17205,
+ 17621, 17941, 19077, 19381, 20245, 22845, 23733, 24869,
+ 25453, 27213, 28381, 28965, 29245, 29997, 30733, 30901,
+ 34877, 35485, 35613, 36133, 36661, 36917, 38597, 40285,
+ 40693, 41413, 41541, 41637, 42053, 42349, 45245, 45469,
+ 46493, 48205, 48613, 50861, 51861, 52877, 53933, 54397,
+ 55669, 56453, 56965, 58021, 7757, 7781, 8333, 9661,
+ 12229, 14373, 14453, 17549, 18141, 19085, 20773, 23701,
+ 24205, 24333, 25261, 25317, 27181, 30117, 30477, 34757,
+ 34885, 35565, 35885, 36541, 37957, 39733, 39813, 41157,
+ 41893, 42317, 46621, 48117, 48181, 49525, 55261, 55389,
+ 56845, 7045, 7749, 7965, 8469, 9133, 9549, 9789,
+ 10173, 11181, 11285, 12253, 13453, 13533, 13757, 14477,
+ 15053, 16901, 17213, 17269, 17525, 17629, 18605, 19013,
+ 19829, 19933, 20069, 20093, 23261, 23333, 24949, 25309,
+ 27613, 28453, 28709, 29301, 29541, 34165, 34413, 37301,
+ 37773, 38045, 38405, 41077, 41781, 41925, 42717, 44437,
+ 44525, 44613, 45933, 45941, 47077, 50077, 50893, 52117,
+ 5293, 55069, 55989, 58125, 59205, 6869, 14685, 15453,
+ 16821, 17045, 17613, 18437, 21029, 22773, 22909, 25445,
+ 25757, 26541, 30709, 30909, 31093, 31149, 37069, 37725,
+ 37925, 38949, 39637, 39701, 40765, 40861, 42965, 44813,
+ 45077, 45733, 47045, 50093, 52861, 52957, 54181, 56325,
+ 56365, 56381, 56877, 57013, 5741, 58101, 58669, 8613,
+ 10045, 10261, 10653, 10733, 11461, 12261, 14069, 15877,
+ 17757, 21165, 23885, 24701, 26429, 26645, 27925, 28765,
+ 29197, 30189, 31293, 39781, 39909, 40365, 41229, 41453,
+ 41653, 42165, 42365, 47421, 48029, 48085, 52773, 5573,
+ 57037, 57637, 58341, 58357, 58901, 6357, 7789, 9093,
+ 10125, 10709, 10765, 11957, 12469, 13437, 13509, 14773,
+ 15437, 15773, 17813, 18829, 19565, 20237, 23461, 23685,
+ 23725, 23941, 24877, 25461, 26405, 29509, 30285, 35181,
+ 37229, 37893, 38565, 40293, 44189, 44581, 45701, 47381,
+ 47589, 48557, 4941, 51069, 5165, 52797, 53149, 5341,
+ 56301, 56765, 58581, 59493, 59677, 6085, 6349, 8293,
+ 8501, 8517, 11597, 11709, 12589, 12693, 13517, 14909,
+ 17397, 18085, 21101, 21269, 22717, 25237, 25661, 29189,
+ 30101, 31397, 33933, 34213, 34661, 35533, 36493, 37309,
+ 40037, 4189, 42909, 44309, 44357, 44389, 4541, 45461,
+ 46445, 48237, 54149, 55301, 55853, 56621, 56717, 56901,
+ 5813, 58437, 12493, 15365, 15989, 17829, 18229, 19341,
+ 21013, 21357, 22925, 24885, 26053, 27581, 28221, 28485,
+ 30605, 30613, 30789, 35437, 36285, 37189, 3941, 41797,
+ 4269, 42901, 43293, 44645, 45221, 46893, 4893, 50301,
+ 50325, 5189, 52109, 53517, 54053, 54485, 5525, 55949,
+ 56973, 59069, 59421, 60733, 61253, 6421, 6701, 6709,
+ 7101, 8669, 15797, 19221, 19837, 20133, 20957, 21293,
+ 21461, 22461, 29085, 29861, 30869, 34973, 36469, 37565,
+ 38125, 38829, 39469, 40061, 40117, 44093, 47429, 48341,
+ 50597, 51757, 5541, 57629, 58405, 59621, 59693, 59701,
+ 61837, 7061, 10421, 11949, 15405, 20861, 25397, 25509,
+ 25893, 26037, 28629, 28869, 29605, 30213, 34205, 35637,
+ 36365, 37285, 3773, 39117, 4021, 41061, 42653, 44509,
+ 4461, 44829, 4725, 5125, 52269, 56469, 59085, 5917,
+ 60973, 8349, 17725, 18637, 19773, 20293, 21453, 22533,
+ 24285, 26333, 26997, 31501, 34541, 34805, 37509, 38477,
+ 41333, 44125, 46285, 46997, 47637, 48173, 4925, 50253,
+ 50381, 50917, 51205, 51325, 52165, 52229, 5253, 5269,
+ 53509, 56253, 56341, 5821, 58373, 60301, 61653, 61973,
+ 62373, 8397, 11981, 14341, 14509, 15077, 22261, 22429,
+ 24261, 28165, 28685, 30661, 34021, 34445, 39149, 3917,
+ 43013, 43317, 44053, 44101, 4533, 49541, 49981, 5277,
+ 54477, 56357, 57261, 57765, 58573, 59061, 60197, 61197,
+ 62189, 7725, 8477, 9565, 10229, 11437, 14613, 14709,
+ 16813, 20029, 20677, 31445, 3165, 31957, 3229, 33541,
+ 36645, 3805, 38973, 3965, 4029, 44293, 44557, 46245,
+ 48917, 4909, 51749, 53709, 55733, 56445, 5925, 6093,
+ 61053, 62637, 8661, 9109, 10821, 11389, 13813, 14325,
+ 15501, 16149, 18845, 22669, 26437, 29869, 31837, 33709,
+ 33973, 34173, 3677, 3877, 3981, 39885, 42117, 4421,
+ 44221, 44245, 44693, 46157, 47309, 5005, 51461, 52037,
+ 55333, 55693, 56277, 58949, 6205, 62141, 62469, 6293,
+ 10101, 12509, 14029, 17997, 20469, 21149, 25221, 27109,
+ 2773, 2877, 29405, 31493, 31645, 4077, 42005, 42077,
+ 42469, 42501, 44013, 48653, 49349, 4997, 50101, 55405,
+ 56957, 58037, 59429, 60749, 61797, 62381, 62837, 6605,
+ 10541, 23981, 24533, 2701, 27333, 27341, 31197, 33805,
+ 3621, 37381, 3749, 3829, 38533, 42613, 44381, 45901,
+ 48517, 51269, 57725, 59461, 60045, 62029, 13805, 14013,
+ 15461, 16069, 16157, 18573, 2309, 23501, 28645, 3077,
+ 31541, 36357, 36877, 3789, 39429, 39805, 47685, 47949,
+ 49413, 5485, 56757, 57549, 57805, 58317, 59549, 62213,
+ 62613, 62853, 62933, 8909, 12941, 16677, 20333, 21541,
+ 24429, 26077, 26421, 2885, 31269, 33381, 3661, 40925,
+ 42925, 45173, 4525, 4709, 53133, 55941, 57413, 57797,
+ 62125, 62237, 62733, 6773, 12317, 13197, 16533, 16933,
+ 18245, 2213, 2477, 29757, 33293, 35517, 40133, 40749,
+ 4661, 49941, 62757, 7853, 8149, 8573, 11029, 13421,
+ 21549, 22709, 22725, 24629, 2469, 26125, 2669, 34253,
+ 36709, 41013, 45597, 46637, 52285, 52333, 54685, 59013,
+ 60997, 61189, 61981, 62605, 62821, 7077, 7525, 8781,
+ 10861, 15277, 2205, 22077, 28517, 28949, 32109, 33493,
+ 3685, 39197, 39869, 42621, 44997, 48565, 5221, 57381,
+ 61749, 62317, 63245, 63381, 23149, 2549, 28661, 31653,
+ 33885, 36341, 37053, 39517, 42805, 45853, 48997, 59349,
+ 60053, 62509, 63069, 6525, 1893, 20181, 2365, 24893,
+ 27397, 31357, 32277, 33357, 34437, 36677, 37661, 43469,
+ 43917, 50997, 53869, 5653, 13221, 16741, 17893, 2157,
+ 28653, 31789, 35301, 35821, 61613, 62245, 12405, 14517,
+ 17453, 18421, 3149, 3205, 40341, 4109, 43941, 46869,
+ 48837, 50621, 57405, 60509, 62877, 8157, 12933, 12957,
+ 16501, 19533, 3461, 36829, 52357, 58189, 58293, 63053,
+ 17109, 1933, 32157, 37701, 59005, 61621, 13029, 15085,
+ 16493, 32317, 35093, 5061, 51557, 62221, 20765, 24613,
+ 2629, 30861, 33197, 33749, 35365, 37933, 40317, 48045,
+ 56229, 61157, 63797, 7917, 17965, 1917, 1973, 20301,
+ 2253, 33157, 58629, 59861, 61085, 63909, 8141, 9221,
+ 14757, 1581, 21637, 26557, 33869, 34285, 35733, 40933,
+ 42517, 43501, 53653, 61885, 63805, 7141, 21653, 54973,
+ 31189, 60061, 60341, 63357, 16045, 2053, 26069, 33997,
+ 43901, 54565, 63837, 8949, 17909, 18693, 32349, 33125,
+ 37293, 48821, 49053, 51309, 64037, 7117, 1445, 20405,
+ 23085, 26269, 26293, 27349, 32381, 33141, 34525, 36461,
+ 37581, 43525, 4357, 43877, 5069, 55197, 63965, 9845,
+ 12093, 2197, 2229, 32165, 33469, 40981, 42397, 8749,
+ 10853, 1453, 18069, 21693, 30573, 36261, 37421, 42533
+};
+#define NSID_MULT_TABLE_SIZE \
+ ((sizeof nsid_multiplier_table)/(sizeof nsid_multiplier_table[0]))
+
+void
+nsid_init() {
+ struct timeval now;
+ pid_t mypid;
+ u_int16_t a1ndx, a2ndx, a3ndx, c1ndx, c2ndx, c3ndx;
+ int i;
+
+ if (nsid_algorithm != 0)
+ return;
+
+ gettimeofday(&now, NULL);
+ mypid = getpid();
+
+ /* Initialize the state */
+ nsid_hash_state = 0;
+ nsid_hash((u_char *)&now, sizeof now);
+ nsid_hash((u_char *)&mypid, sizeof mypid);
+
+ /*
+ * Select our random number generators and initial seed.
+ * We could really use more random bits at this point,
+ * but we'll try to make a silk purse out of a sows ear ...
+ */
+ /* generator 1 */
+ a1ndx = ((u_long) NSID_MULT_TABLE_SIZE *
+ (nsid_hash_state & 0xFFFF)) >> 16;
+ nsid_a1 = nsid_multiplier_table[a1ndx];
+ c1ndx = (nsid_hash_state >> 9) & 0x7FFF;
+ nsid_c1 = 2*c1ndx + 1;
+ /* generator 2, distinct from 1 */
+ a2ndx = ((u_long) (NSID_MULT_TABLE_SIZE - 1) *
+ ((nsid_hash_state >> 10) & 0xFFFF)) >> 16;
+ if (a2ndx >= a1ndx)
+ a2ndx++;
+ nsid_a2 = nsid_multiplier_table[a2ndx];
+ c2ndx = nsid_hash_state % 32767;
+ if (c2ndx >= c1ndx)
+ c2ndx++;
+ nsid_c2 = 2*c2ndx + 1;
+ /* generator 3, distinct from 1 and 2 */
+ a3ndx = ((u_long) (NSID_MULT_TABLE_SIZE - 2) *
+ ((nsid_hash_state >> 20) & 0xFFFF)) >> 16;
+ if (a3ndx >= a1ndx || a3ndx >= a2ndx)
+ a3ndx++;
+ if (a3ndx >= a1ndx && a3ndx >= a2ndx)
+ a3ndx++;
+ nsid_a3 = nsid_multiplier_table[a3ndx];
+ c3ndx = nsid_hash_state % 32766;
+ if (c3ndx >= c1ndx || c3ndx >= c2ndx)
+ c3ndx++;
+ if (c3ndx >= c1ndx && c3ndx >= c2ndx)
+ c3ndx++;
+ nsid_c3 = 2*c3ndx + 1;
+
+ nsid_state = ((nsid_hash_state >> 16) ^ (nsid_hash_state)) & 0xFFFF;
+
+
+ /* Do the algorithm specific initialization */
+ INSIST(server_options != NULL);
+ if (NS_OPTION_P(OPTION_USE_ID_POOL) == 0) {
+ /* Algorithm 1 */
+ nsid_algorithm = 1;
+ nsid_vtable = malloc(NSID_SHUFFLE_TABLE_SIZE *
+ (sizeof(u_int16_t)) );
+ if (!nsid_vtable)
+ ns_panic(ns_log_default, 1, "malloc(nsid_vtable)",
+ NULL);
+ for (i = 0; i < NSID_SHUFFLE_TABLE_SIZE; i++) {
+ nsid_vtable[i] = nsid_state;
+ nsid_state = (((u_long) nsid_a1 * nsid_state) + nsid_c1)
+ & 0xFFFF;
+ }
+ nsid_state2 = nsid_state;
+ } else {
+ /* Algorithm 2 */
+ nsid_algorithm = 2;
+ nsid_pool = malloc(0x10000 * (sizeof(u_int16_t)));
+ if (!nsid_pool)
+ ns_panic(ns_log_default, 1, "malloc(nsid_pool)", NULL);
+ for (i = 0; ; i++) {
+ nsid_pool[i] = nsid_state;
+ nsid_state = (((u_long) nsid_a1 * nsid_state) + nsid_c1) & 0xFFFF;
+ if (i == 0xFFFF)
+ break;
+ }
+ }
+}
+
+#define NSID_RANGE_MASK (NSID_LOOKAHEAD - 1)
+
+#define NSID_POOL_MASK 0xFFFF /* used to wrap the pool index */
+
+u_int16_t
+nsid_next() {
+ u_int16_t id, compressed_hash;
+
+ compressed_hash = ((nsid_hash_state >> 16) ^ (nsid_hash_state)) &
+ 0xFFFF;
+ if (nsid_algorithm == 1) {
+ u_int16_t j;
+
+ /*
+ * This is the original Algorithm B
+ * j = ((u_long) NSID_SHUFFLE_TABLE_SIZE * nsid_state2)
+ * >> 16;
+ *
+ * We'll perturb it with some random stuff ...
+ */
+ j = ((u_long) NSID_SHUFFLE_TABLE_SIZE *
+ (nsid_state2 ^ compressed_hash)) >> 16;
+ nsid_state2 = id = nsid_vtable[j];
+ nsid_state = (((u_long) nsid_a1 * nsid_state) + nsid_c1) &
+ 0xFFFF;
+ nsid_vtable[j] = nsid_state;
+ } else if (nsid_algorithm == 2) {
+ u_int16_t pick;
+
+ pick = compressed_hash & NSID_RANGE_MASK;
+ id = nsid_pool[(nsid_state + pick) & NSID_POOL_MASK];
+ if (pick != 0) {
+ /* Swap two IDs to stir the pool */
+ nsid_pool[(nsid_state + pick) & NSID_POOL_MASK] =
+ nsid_pool[nsid_state];
+ nsid_pool[nsid_state] = id;
+ }
+
+ /* increment the base pointer into the pool */
+ if (nsid_state == 65535)
+ nsid_state = 0;
+ else
+ nsid_state++;
+ } else
+ ns_panic(ns_log_default, 1, "Unknown ID algorithm", NULL);
+
+ /* Now lets obfuscate ... */
+ id = (((u_long) nsid_a2 * id) + nsid_c2) & 0xFFFF;
+ id = (((u_long) nsid_a3 * id) + nsid_c3) & 0xFFFF;
+
+ return (id);
+}
+#else /* RANDOMIZE_ID */
void
nsid_init() {
nsid_state = res_randomid();
@@ -1815,6 +2216,7 @@
nsid_state++;
return (nsid_state);
}
+#endif /* RANDOMIZE_ID */
static void
deallocate_everything(void) {
Index: ns_parser.y
===================================================================
RCS file: /proj/named/BIND8/src/bin/named/ns_parser.y,v
retrieving revision 1.1.1.2
retrieving revision 1.3
diff -u -r1.1.1.2 -r1.3
--- ns_parser.y 1997/12/11 11:26:58 1.1.1.2
+++ ns_parser.y 1998/01/21 11:32:52 1.3
@@ -137,6 +137,7 @@
%type <axfr_fmt> transfer_format
%token T_NOTIFY T_AUTH_NXDOMAIN T_MULTIPLE_CNAMES
%token T_CLEAN_INTERVAL T_INTERFACE_INTERVAL T_STATS_INTERVAL
+%token T_USE_ID_POOL
/* Items used for the "logging" statement: */
%token T_LOGGING T_CATEGORY T_CHANNEL T_SEVERITY T_DYNAMIC
@@ -324,6 +328,10 @@
set_boolean_option(current_options, OPTION_MULTIPLE_CNAMES,
$2);
}
+ | T_USE_ID_POOL yea_or_nay
+ {
+ set_boolean_option(current_options, OPTION_USE_ID_POOL, $2);
+ }
| T_CHECK_NAMES check_names_type check_names_opt
{
current_options->check_names[$2] = $3;
Index: ns_req.c
===================================================================
RCS file: /proj/named/BIND8/src/bin/named/ns_req.c,v
retrieving revision 1.1.1.2
retrieving revision 1.4
diff -u -r1.1.1.2 -r1.4
--- ns_req.c 1997/12/11 11:27:03 1.1.1.2
+++ ns_req.c 1998/01/21 11:32:54 1.4
@@ -177,6 +177,12 @@
}
#endif
+#ifdef RANDOMIZE_ID
+ /* Hash some stuff so it's nice and random */
+ nsid_hash((char *)&tt, sizeof(tt));
+ nsid_hash(msg, (msglen > 512) ? 512 : msglen);
+#endif /* RANDOMIZE_ID
+
/*
* It's not a response so these bits have no business
* being set. will later simplify work if we can
