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resolv: Fix resolv_conf _res matching 

A dot-less host name without an /etc/resolv.conf file caused an
assertion failure in update_from_conf because the function would not
deal correctly with the empty search list case.

Thanks to Andreas Schwab for debugging assistence.
This commit is contained in:
Florian Weimer 2017-07-04 14:47:29 +02:00
parent f0107724c9
commit 4446a885f3
3 changed files with 61 additions and 5 deletions
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11
ChangeLog
View File

@ -1,3 +1,14 @@
2017-07-04 Florian Weimer <fweimer@redhat.com>
* resolv/resolv_conf.c (resolv_conf_matches): Tighten check for name
server and sort list counts. Fix improper check for empty search
path (completely missing domain name) leading to assertion failure
in update_from_conf.
* resolv/tst-resolv-res_init-skeleton.c (struct test_case): Add
hostname member.
(run_res_init): Set host name if requested.
(test_cases): Update.
2017-07-04 Joseph Myers <joseph@codesourcery.com>
* scripts/build-many-glibcs.py (Context.checkout): Default

24
resolv/resolv_conf.c
View File

@ -272,7 +272,7 @@ resolv_conf_matches (const struct __res_state *resp,
nserv = MAXNS;
/* _ext.nscount is 0 until initialized by res_send.c. */
if (resp->nscount != nserv
&& (resp->_u._ext.nscount != 0 && resp->_u._ext.nscount != nserv))
|| (resp->_u._ext.nscount != 0 && resp->_u._ext.nscount != nserv))
return false;
for (size_t i = 0; i < nserv; ++i)
{
@ -295,9 +295,25 @@ resolv_conf_matches (const struct __res_state *resp,
/* Check that the search list in *RESP has not been modified by the
application. */
{
if (!(resp->dnsrch[0] == resp->defdname
&& resp->dnsrch[MAXDNSRCH] == NULL))
if (resp->dnsrch[0] == NULL)
{
/* Empty search list. No default domain name. */
return conf->search_list_size == 0 && resp->defdname[0] == '\0';
}
if (resp->dnsrch[0] != resp->defdname)
/* If the search list is not empty, it must start with the
default domain name. */
return false;
size_t nsearch;
for (nsearch = 0; nsearch < MAXDNSRCH; ++nsearch)
if (resp->dnsrch[nsearch] == NULL)
break;
if (nsearch > MAXDNSRCH)
/* Search list is not null-terminated. */
return false;
size_t search_list_size = 0;
for (size_t i = 0; i < conf->search_list_size; ++i)
{
@ -326,6 +342,8 @@ resolv_conf_matches (const struct __res_state *resp,
size_t nsort = conf->sort_list_size;
if (nsort > MAXRESOLVSORT)
nsort = MAXRESOLVSORT;
if (resp->nsort != nsort)
return false;
for (size_t i = 0; i < nsort; ++i)
if (resp->sort_list[i].addr.s_addr != conf->sort_list[i].addr.s_addr
|| resp->sort_list[i].mask != conf->sort_list[i].mask)

31
resolv/tst-resolv-res_init-skeleton.c
View File

@ -307,6 +307,10 @@ struct test_case
/* Setting for the RES_OPTIONS environment variable. NULL if the
variable is not to be set. */
const char *res_options;
/* Override the system host name. NULL means that no change is made
and the default is used (test_hostname). */
const char *hostname;
};
enum test_init
@ -358,6 +362,14 @@ run_res_init (void *closure)
setenv ("LOCALDOMAIN", ctx->t->localdomain, 1);
if (ctx->t->res_options != NULL)
setenv ("RES_OPTIONS", ctx->t->res_options, 1);
if (ctx->t->hostname != NULL)
{
/* This test needs its own namespace, to avoid changing the host
name for the parent, too. */
TEST_VERIFY_EXIT (unshare (CLONE_NEWUTS) == 0);
if (sethostname (ctx->t->hostname, strlen (ctx->t->hostname)) != 0)
FAIL_EXIT1 ("sethostname (\"%s\"): %m", ctx->t->hostname);
}
switch (ctx->init)
{
@ -434,6 +446,12 @@ struct test_case test_cases[] =
"nameserver 127.0.0.1\n"
"; nameserver[0]: [127.0.0.1]:53\n"
},
{.name = "empty file, no-dot hostname",
.conf = "",
.expected = "nameserver 127.0.0.1\n"
"; nameserver[0]: [127.0.0.1]:53\n",
.hostname = "example",
},
{.name = "empty file with LOCALDOMAIN",
.conf = "",
.expected = "search example.net\n"
@ -462,8 +480,7 @@ struct test_case test_cases[] =
.res_options = "edns0 attempts:5",
},
{.name = "basic",
.conf = "domain example.net\n"
"search corp.example.com example.com\n"
.conf = "search corp.example.com example.com\n"
"nameserver 192.0.2.1\n",
.expected = "search corp.example.com example.com\n"
"; search[0]: corp.example.com\n"
@ -471,6 +488,16 @@ struct test_case test_cases[] =
"nameserver 192.0.2.1\n"
"; nameserver[0]: [192.0.2.1]:53\n"
},
{.name = "basic with no-dot hostname",
.conf = "search corp.example.com example.com\n"
"nameserver 192.0.2.1\n",
.expected = "search corp.example.com example.com\n"
"; search[0]: corp.example.com\n"
"; search[1]: example.com\n"
"nameserver 192.0.2.1\n"
"; nameserver[0]: [192.0.2.1]:53\n",
.hostname = "example",
},
{.name = "basic no-reload",
.conf = "options no-reload\n"
"search corp.example.com example.com\n"