pull up rt23310 to v9_8

diff --git a/CHANGES b/CHANGES
index 9388013f71fa81e7079f1f80ceeacf2d687135eb..940a2dbbd4584a37f1e1c0238468b3790f6aeca6 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+3024. [func]           RTT Banding removed due to minor security increase
+                       but major impact on resolver latency. [RT #23310]
+
 3023.  [bug]           Named could be left in an inconsistent state when
                        receiving multiple AXFR response messages that were
                        not all TSIG-signed. [RT #23254]

diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index 842c4b12c1e852fb90c140abe9fd6992812ad279..44509961c574cd911575352e50444521374d9608 100644 (file)
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: resolver.c,v 1.428.6.3 2011/02/08 22:56:53 marka Exp $ */
+/* $Id: resolver.c,v 1.428.6.4 2011/02/18 23:04:04 mgraff Exp $ */
 
 /*! \file */
 
@@ -2362,77 +2362,13 @@ add_bad(fetchctx_t *fctx, dns_adbaddrinfo_t *addrinfo, isc_result_t reason,
 }
 
 /*
- * Return 'bits' bits of random entropy from fctx->rand_buf,
- * refreshing it by calling isc_random_get() whenever the requested
- * number of bits is greater than the number in the buffer.
- */
-static inline isc_uint32_t
-random_bits(fetchctx_t *fctx, isc_uint32_t bits) {
-       isc_uint32_t ret = 0;
-
-       REQUIRE(VALID_FCTX(fctx));
-       REQUIRE(bits <= 32);
-       if (bits == 0)
-               return (0);
-
-       if (bits >= fctx->rand_bits) {
-               /* if rand_bits == 0, this is unnecessary but harmless */
-               bits -= fctx->rand_bits;
-               ret = fctx->rand_buf << bits;
-
-               /* refresh random buffer now */
-               isc_random_get(&fctx->rand_buf);
-               fctx->rand_bits = sizeof(fctx->rand_buf) * CHAR_BIT;
-       }
-
-       if (bits > 0) {
-               isc_uint32_t mask = 0xffffffff;
-               if (bits < 32) {
-                       mask = (1 << bits) - 1;
-               }
-
-               ret |= fctx->rand_buf & mask;
-               fctx->rand_buf >>= bits;
-               fctx->rand_bits -= bits;
-       }
-
-       return (ret);
-}
-
-/*
- * Add some random jitter to a server's RTT value so that the
- * order of queries will be unpredictable.
- *
- * RTT values of servers which have been tried are fuzzed by 128 ms.
- * Servers that haven't been tried yet have their RTT set to a random
- * value between 0 ms and 7 ms; they should get to go first, but in
- * unpredictable order.
- */
-static inline void
-randomize_srtt(fetchctx_t *fctx, dns_adbaddrinfo_t *ai) {
-       if (TRIED(ai)) {
-               ai->srtt >>= 10; /* convert to milliseconds, near enough */
-               ai->srtt |= (ai->srtt & 0x80) | random_bits(fctx, 7);
-               ai->srtt <<= 10; /* now back to microseconds */
-       } else
-               ai->srtt = random_bits(fctx, 3) << 10;
-}
-
-/*
- * Sort addrinfo list by RTT (with random jitter)
+ * Sort addrinfo list by RTT.
  */
 static void
 sort_adbfind(fetchctx_t *fctx, dns_adbfind_t *find) {
        dns_adbaddrinfo_t *best, *curr;
        dns_adbaddrinfolist_t sorted;
 
-       /* Add jitter to SRTT values */
-       curr = ISC_LIST_HEAD(find->list);
-       while (curr != NULL) {
-               randomize_srtt(fctx, curr);
-               curr = ISC_LIST_NEXT(curr, publink);
-       }
-
        /* Lame N^2 bubble sort. */
        ISC_LIST_INIT(sorted);
        while (!ISC_LIST_EMPTY(find->list)) {
@@ -2450,7 +2386,7 @@ sort_adbfind(fetchctx_t *fctx, dns_adbfind_t *find) {
 }
 
 /*
- * Sort a list of finds by server RTT (with random jitter)
+ * Sort a list of finds by server RTT.
  */
 static void
 sort_finds(fetchctx_t *fctx, dns_adbfindlist_t *findlist) {
@@ -2458,7 +2394,7 @@ sort_finds(fetchctx_t *fctx, dns_adbfindlist_t *findlist) {
        dns_adbfindlist_t sorted;
        dns_adbaddrinfo_t *addrinfo, *bestaddrinfo;
 
-       /* Sort each find's addrinfo list by SRTT (after adding jitter) */
+       /* Sort each find's addrinfo list by SRTT. */
        for (curr = ISC_LIST_HEAD(*findlist);
             curr != NULL;
             curr = ISC_LIST_NEXT(curr, publink))