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authorFlorian Weimer <fweimer@redhat.com>2017-06-30 21:10:23 +0200
committerFlorian Weimer <fweimer@redhat.com>2017-07-03 20:52:59 +0200
commit352f4ff9a268b81ef5d4b2413f582565806e4790 (patch)
treefb27056dfdeafe43c021f6127c9544c016e78019 /nss
parent4e45d83c92dbb5b8dc20654f32395108d18cf739 (diff)
downloadglibc-352f4ff9a268b81ef5d4b2413f582565806e4790.tar.gz
resolv: Introduce struct resolv_context [BZ #21668]
struct resolv_context objects provide a temporary resolver context which does not change during a name lookup operation. Only when the outmost context is created, the stub resolver configuration is verified to be current (at present, only against previous res_init calls). Subsequent attempts to obtain the context will reuse the result of the initial verification operation. struct resolv_context can also be extended in the future to store data which needs to be deallocated during thread cancellation.
Diffstat (limited to 'nss')
-rw-r--r--nss/digits_dots.c21
-rw-r--r--nss/getXXbyYY.c28
-rw-r--r--nss/getXXbyYY_r.c34
-rw-r--r--nss/getnssent_r.c42
-rw-r--r--nss/nsswitch.h10
5 files changed, 105 insertions, 30 deletions
diff --git a/nss/digits_dots.c b/nss/digits_dots.c
index 8dcbf9eb0a..0c1fa97e39 100644
--- a/nss/digits_dots.c
+++ b/nss/digits_dots.c
@@ -23,6 +23,7 @@
#include <ctype.h>
#include <wctype.h>
#include <resolv/resolv-internal.h>
+#include <resolv/resolv_context.h>
#include <netdb.h>
#include <arpa/inet.h>
#include "nsswitch.h"
@@ -38,11 +39,10 @@ __nss_hostname_digits_dots (const char *name, struct hostent *resbuf,
size_t buflen, struct hostent **result,
enum nss_status *status, int af, int *h_errnop)
{
- int save;
-
/* We have to test for the use of IPv6 which can only be done by
examining `_res'. */
- if (__res_maybe_init (&_res, 0) == -1)
+ struct resolv_context *ctx = __resolv_context_get ();
+ if (ctx == NULL)
{
if (h_errnop)
*h_errnop = NETDB_INTERNAL;
@@ -52,6 +52,21 @@ __nss_hostname_digits_dots (const char *name, struct hostent *resbuf,
*result = NULL;
return -1;
}
+ int ret = __nss_hostname_digits_dots_context
+ (ctx, name, resbuf, buffer, buffer_size, buflen,
+ result, status, af, h_errnop);
+ __resolv_context_put (ctx);
+ return ret;
+}
+
+int
+__nss_hostname_digits_dots_context (struct resolv_context *ctx,
+ const char *name, struct hostent *resbuf,
+ char **buffer, size_t *buffer_size,
+ size_t buflen, struct hostent **result,
+ enum nss_status *status, int af, int *h_errnop)
+{
+ int save;
/*
* disallow names consisting only of digits/dots, unless
diff --git a/nss/getXXbyYY.c b/nss/getXXbyYY.c
index d027b14250..a439b816f7 100644
--- a/nss/getXXbyYY.c
+++ b/nss/getXXbyYY.c
@@ -47,6 +47,11 @@
|* *|
\*******************************************************************/
+
+#ifdef HANDLE_DIGITS_DOTS
+# include <resolv/resolv_context.h>
+#endif
+
/* To make the real sources a bit prettier. */
#define REENTRANT_NAME APPEND_R (FUNCTION_NAME)
#define APPEND_R(name) APPEND_R1 (name)
@@ -93,6 +98,19 @@ FUNCTION_NAME (ADD_PARAMS)
int h_errno_tmp = 0;
#endif
+#ifdef HANDLE_DIGITS_DOTS
+ /* Wrap both __nss_hostname_digits_dots and the actual lookup
+ function call in the same context. */
+ struct resolv_context *res_ctx = __resolv_context_get ();
+ if (res_ctx == NULL)
+ {
+# if NEED_H_ERRNO
+ __set_h_errno (NETDB_INTERNAL);
+# endif
+ return NULL;
+ }
+#endif
+
/* Get lock. */
__libc_lock_lock (lock);
@@ -105,9 +123,9 @@ FUNCTION_NAME (ADD_PARAMS)
#ifdef HANDLE_DIGITS_DOTS
if (buffer != NULL)
{
- if (__nss_hostname_digits_dots (name, &resbuf, &buffer,
- &buffer_size, 0, &result, NULL, AF_VAL,
- H_ERRNO_VAR_P))
+ if (__nss_hostname_digits_dots_context
+ (res_ctx, name, &resbuf, &buffer, &buffer_size, 0, &result, NULL,
+ AF_VAL, H_ERRNO_VAR_P))
goto done;
}
#endif
@@ -143,6 +161,10 @@ done:
/* Release lock. */
__libc_lock_unlock (lock);
+#ifdef HANDLE_DIGITS_DOTS
+ __resolv_context_put (res_ctx);
+#endif
+
#ifdef NEED_H_ERRNO
if (h_errno_tmp != 0)
__set_h_errno (h_errno_tmp);
diff --git a/nss/getXXbyYY_r.c b/nss/getXXbyYY_r.c
index 7cab825cf0..6c547ea1ca 100644
--- a/nss/getXXbyYY_r.c
+++ b/nss/getXXbyYY_r.c
@@ -26,7 +26,7 @@
# include <nscd/nscd_proto.h>
#endif
#ifdef NEED__RES
-# include <resolv.h>
+# include <resolv/resolv_context.h>
#endif
/*******************************************************************\
|* Here we assume several symbols to be defined: *|
@@ -53,8 +53,7 @@
|* NEED_H_ERRNO - an extra parameter will be passed to point to *|
|* the global `h_errno' variable. *|
|* *|
-|* NEED__RES - the global _res variable might be used so we *|
-|* will have to initialize it if necessary *|
+|* NEED__RES - obtain a struct resolv_context resolver context *|
|* *|
|* PREPROCESS - code run before anything else *|
|* *|
@@ -213,6 +212,18 @@ INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
bool any_service = false;
#endif
+#ifdef NEED__RES
+ /* The HANDLE_DIGITS_DOTS case below already needs the resolver
+ configuration, so this has to happen early. */
+ struct resolv_context *res_ctx = __resolv_context_get ();
+ if (res_ctx == NULL)
+ {
+ *h_errnop = NETDB_INTERNAL;
+ *result = NULL;
+ return errno;
+ }
+#endif /* NEED__RES */
+
#ifdef PREPROCESS
PREPROCESS;
#endif
@@ -260,17 +271,6 @@ INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
}
else
{
-#ifdef NEED__RES
- /* The resolver code will really be used so we have to
- initialize it. */
- if (__res_maybe_init (&_res, 0) == -1)
- {
- *h_errnop = NETDB_INTERNAL;
- *result = NULL;
- return errno;
- }
-#endif /* need _res */
-
void *tmp_ptr = fct.l;
#ifdef PTR_MANGLE
PTR_MANGLE (tmp_ptr);
@@ -399,6 +399,12 @@ done:
POSTPROCESS;
#endif
+#ifdef NEED__RES
+ /* This has to happen late because the POSTPROCESS stage above might
+ need the resolver context. */
+ __resolv_context_put (res_ctx);
+#endif /* NEED__RES */
+
int res;
if (status == NSS_STATUS_SUCCESS || status == NSS_STATUS_NOTFOUND)
res = 0;
diff --git a/nss/getnssent_r.c b/nss/getnssent_r.c
index 5fdbf3be00..d85065b6cc 100644
--- a/nss/getnssent_r.c
+++ b/nss/getnssent_r.c
@@ -18,6 +18,7 @@
#include <errno.h>
#include <netdb.h>
#include "nsswitch.h"
+#include <resolv/resolv_context.h>
/* Set up NIP to run through the services. If ALL is zero, use NIP's
current location if it's not nil. Return nonzero if there are no
@@ -59,10 +60,15 @@ __nss_setent (const char *func_name, db_lookup_function lookup_fct,
} fct;
int no_more;
- if (res && __res_maybe_init (&_res, 0) == -1)
+ struct resolv_context *res_ctx = NULL;
+ if (res)
{
- __set_h_errno (NETDB_INTERNAL);
- return;
+ res_ctx = __resolv_context_get ();
+ if (res_ctx == NULL)
+ {
+ __set_h_errno (NETDB_INTERNAL);
+ return;
+ }
}
/* Cycle through the services and run their `setXXent' functions until
@@ -95,6 +101,8 @@ __nss_setent (const char *func_name, db_lookup_function lookup_fct,
*last_nip = *nip;
}
+ __resolv_context_put (res_ctx);
+
if (stayopen_tmp)
*stayopen_tmp = stayopen;
}
@@ -112,10 +120,15 @@ __nss_endent (const char *func_name, db_lookup_function lookup_fct,
} fct;
int no_more;
- if (res && __res_maybe_init (&_res, 0) == -1)
+ struct resolv_context *res_ctx = NULL;
+ if (res)
{
- __set_h_errno (NETDB_INTERNAL);
- return;
+ res_ctx = __resolv_context_get ();
+ if (res_ctx == NULL)
+ {
+ __set_h_errno (NETDB_INTERNAL);
+ return;
+ }
}
/* Cycle through all the services and run their endXXent functions. */
@@ -132,6 +145,8 @@ __nss_endent (const char *func_name, db_lookup_function lookup_fct,
no_more = __nss_next2 (nip, func_name, NULL, &fct.ptr, 0, 1);
}
*last_nip = *nip = NULL;
+
+ __resolv_context_put (res_ctx);
}
@@ -152,11 +167,16 @@ __nss_getent_r (const char *getent_func_name,
int no_more;
enum nss_status status;
- if (res && __res_maybe_init (&_res, 0) == -1)
+ struct resolv_context *res_ctx = NULL;
+ if (res)
{
- *h_errnop = NETDB_INTERNAL;
- *result = NULL;
- return errno;
+ res_ctx = __resolv_context_get ();
+ if (res_ctx == NULL)
+ {
+ *h_errnop = NETDB_INTERNAL;
+ *result = NULL;
+ return errno;
+ }
}
/* Initialize status to return if no more functions are found. */
@@ -227,6 +247,8 @@ __nss_getent_r (const char *getent_func_name,
while (! no_more && status != NSS_STATUS_SUCCESS);
}
+ __resolv_context_put (res_ctx);
+
*result = status == NSS_STATUS_SUCCESS ? resbuf : NULL;
return (status == NSS_STATUS_SUCCESS ? 0
: status != NSS_STATUS_TRYAGAIN ? ENOENT
diff --git a/nss/nsswitch.h b/nss/nsswitch.h
index f3e756b684..bd3fbcb082 100644
--- a/nss/nsswitch.h
+++ b/nss/nsswitch.h
@@ -197,7 +197,17 @@ extern int __nss_getent_r (const char *getent_func_name,
extern void *__nss_getent (getent_r_function func,
void **resbuf, char **buffer, size_t buflen,
size_t *buffer_size, int *h_errnop);
+struct resolv_context;
struct hostent;
+extern int __nss_hostname_digits_dots_context (struct resolv_context *,
+ const char *name,
+ struct hostent *resbuf,
+ char **buffer,
+ size_t *buffer_size,
+ size_t buflen,
+ struct hostent **result,
+ enum nss_status *status, int af,
+ int *h_errnop) attribute_hidden;
extern int __nss_hostname_digits_dots (const char *name,
struct hostent *resbuf, char **buffer,
size_t *buffer_size, size_t buflen,