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
This archive was generated by hypermail 2b30 : Fri Apr 13 2001 - 14:23:20 PDT