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author | Daniel Stenberg <daniel@haxx.se> | 2008-08-04 20:23:12 +0000 |
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committer | Daniel Stenberg <daniel@haxx.se> | 2008-08-04 20:23:12 +0000 |
commit | 3f1bde766423bede155941a68f0b00aa97edbf12 (patch) | |
tree | 0550bba538eabd2f4b43e794402e7ea59cc39a87 | |
parent | 5c5e64b2f577e1d1455133e4bb155cc6f9a8f8ba (diff) | |
download | c-ares-3f1bde766423bede155941a68f0b00aa97edbf12.tar.gz c-ares-3f1bde766423bede155941a68f0b00aa97edbf12.tar.bz2 c-ares-3f1bde766423bede155941a68f0b00aa97edbf12.zip |
- Fix by Tofu Linden:
The symptom:
* Users (usually, but not always) on 2-Wire routers and the Comcast service
and a wired connection to their router would find that the second and
subsequent DNS lookups from fresh processes using c-ares to resolve the same
address would cause the process to never see a reply (it keeps polling for
around 1m15s before giving up).
The repro:
* On such a machine (and yeah, it took us a lot of QA to find the systems
that reproduce such a specific problem!), do 'ahost www.secondlife.com',
then do it again. The first process's lookup will work, subsequent lookups
will time-out and fail.
The cause:
* init_id_key() was calling randomize_key() *before* it initialized
key->state, meaning that the randomness generated by randomize_key() is
immediately overwritten with deterministic values. (/dev/urandom was also
being read incorrectly in the c-ares version we were using, but this was
fixed in a later version.)
* This makes the stream of generated query-IDs from any new c-ares process
be an identical and predictable sequence of IDs.
* This makes the 2-Wire's default built-in DNS server detect these queries
as probable-duplicates and (erroneously) not respond at all.
-rw-r--r-- | CHANGES | 28 | ||||
-rw-r--r-- | RELEASE-NOTES | 3 | ||||
-rw-r--r-- | ares_init.c | 2 |
3 files changed, 31 insertions, 2 deletions
@@ -1,5 +1,33 @@ Changelog for the c-ares project +* Aug 4 2008 (Daniel Stenberg) +- Fix by Tofu Linden: + + The symptom: + * Users (usually, but not always) on 2-Wire routers and the Comcast service + and a wired connection to their router would find that the second and + subsequent DNS lookups from fresh processes using c-ares to resolve the same + address would cause the process to never see a reply (it keeps polling for + around 1m15s before giving up). + + The repro: + * On such a machine (and yeah, it took us a lot of QA to find the systems + that reproduce such a specific problem!), do 'ahost www.secondlife.com', + then do it again. The first process's lookup will work, subsequent lookups + will time-out and fail. + + The cause: + * init_id_key() was calling randomize_key() *before* it initialized + key->state, meaning that the randomness generated by randomize_key() is + immediately overwritten with deterministic values. (/dev/urandom was also + being read incorrectly in the c-ares version we were using, but this was + fixed in a later version.) + * This makes the stream of generated query-IDs from any new c-ares process + be an identical and predictable sequence of IDs. + * This makes the 2-Wire's default built-in DNS server detect these queries + as probable-duplicates and (erroneously) not respond at all. + + * Aug 4 2008 (Yang Tse) - Autoconf 2.62 has changed the behaviour of the AC_AIX macro which we use. Prior versions of autoconf defined _ALL_SOURCE if _AIX was defined. 2.62 diff --git a/RELEASE-NOTES b/RELEASE-NOTES index 752c4db..eb9110d 100644 --- a/RELEASE-NOTES +++ b/RELEASE-NOTES @@ -8,10 +8,11 @@ This is what's new and changed in the c-ares 1.5.3 release: o configure process no longer needs nor checks size of curl_off_t o library will now be built with _REENTRANT symbol defined if needed o Improved configure detection of number of arguments for getservbyport_r + o Improved query-ID randomness Thanks go to these friendly people for their efforts and contributions: - Brad House, Yang Tse, Phil Blundell + Brad House, Yang Tse, Phil Blundell, Tofu Linden and obviously Daniel Stenberg Have fun! diff --git a/ares_init.c b/ares_init.c index e33c397..20a23a3 100644 --- a/ares_init.c +++ b/ares_init.c @@ -1464,11 +1464,11 @@ static int init_id_key(rc4_key* key,int key_data_len) if (!key_data_ptr) return ARES_ENOMEM; - randomize_key(key->state,key_data_len); state = &key->state[0]; for(counter = 0; counter < 256; counter++) /* unnecessary AND but it keeps some compilers happier */ state[counter] = (unsigned char)(counter & 0xff); + randomize_key(key->state,key_data_len); key->x = 0; key->y = 0; index1 = 0; |