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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/getXXbyYY_r.c
parent4e45d83c92dbb5b8dc20654f32395108d18cf739 (diff)
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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/getXXbyYY_r.c')
-rw-r--r--nss/getXXbyYY_r.c34
1 files changed, 20 insertions, 14 deletions
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;