Re: [ping][PATCH v2.1][BZ #15339] Avoid returning EAI_SYSTEM when there's a network error

[Siddhesh Poyarekar <siddhesh at redhat dot com>]

On Tue, May 21, 2013 at 11:58:37AM -0400, Carlos O'Donell wrote:
> Could you please add a one sentence comment about this?
> e.g. We use errno from the last failed fallback.
> 

Thanks, this is what I finally committed.

Siddhesh

commit 3d04f5db20c8f0d1ba3881b5f5373586a18cf188
Author: Siddhesh Poyarekar <siddhesh@redhat.com>
Date:   Tue May 21 21:54:41 2013 +0530

    Set EAI_SYSTEM only when h_errno is NETDB_INTERNAL
    
    Fixes BZ #15339.
    
    NSS_STATUS_UNAVAIL may mean that a necessary input resource is not
    available.  This could occur in a number of cases including when the
    network is down, system runs out of file descriptors, etc.  The
    correct differentiator in such a case is the h_errno, which gives the
    nature of failure.  In case of failures other than a simple 'not
    found', we set h_errno as NETDB_INTERNAL and let errno be the
    identifier for the exact error.

diff --git a/ChangeLog b/ChangeLog
index 61377cc..a551413 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2013-05-21  Siddhesh Poyarekar  <siddhesh@redhat.com>
+
+	[BZ #15339]
+	* nss/getXXbyYY_r.c (REENTRANT_NAME): Set NETDB_INTERNAL only
+	when no services were used.
+	* sysdeps/posix/getaddrinfo.c (gaih_inet): Set h_errno.
+	Return EAI_SYSTEM if h_errno is NETDB_INTERNAL.
+
 2013-05-21  Andreas Schwab  <schwab@suse.de>
 
 	[BZ #15014]
diff --git a/NEWS b/NEWS
index 420c31e..68a55ea 100644
--- a/NEWS
+++ b/NEWS
@@ -15,10 +15,10 @@ Version 2.18
   14952, 14964, 14981, 14982, 14985, 14994, 14996, 15000, 15003, 15006,
   15007, 15014, 15020, 15023, 15036, 15054, 15055, 15062, 15078, 15084,
   15085, 15086, 15160, 15214, 15221, 15232, 15234, 15283, 15285, 15287,
-  15304, 15305, 15307, 15309, 15327, 15330, 15335, 15336, 15337, 15342,
-  15346, 15359, 15361, 15366, 15380, 15394, 15395, 15405, 15406, 15409,
-  15416, 15418, 15419, 15423, 15424, 15426, 15429, 15442, 15448, 15480,
-  15485, 15488, 15490, 15493, 15497.
+  15304, 15305, 15307, 15309, 15327, 15330, 15335, 15336, 15337, 15339,
+  15342, 15346, 15359, 15361, 15366, 15380, 15394, 15395, 15405, 15406,
+  15409, 15416, 15418, 15419, 15423, 15424, 15426, 15429, 15442, 15448,
+  15480, 15485, 15488, 15490, 15493, 15497.
 
 * CVE-2013-0242 Buffer overrun in regexp matcher has been fixed (Bugzilla
   #15078).
diff --git a/nss/getXXbyYY_r.c b/nss/getXXbyYY_r.c
index 44d00f4..33e63d4 100644
--- a/nss/getXXbyYY_r.c
+++ b/nss/getXXbyYY_r.c
@@ -287,10 +287,10 @@ done:
 #endif
   *result = status == NSS_STATUS_SUCCESS ? resbuf : NULL;
 #ifdef NEED_H_ERRNO
-  if (status == NSS_STATUS_UNAVAIL)
-    /* Either we failed to lookup the functions or the functions themselves
-       had a system error.  Set NETDB_INTERNAL here to let the caller know
-       that the errno may have the real reason for failure.  */
+  if (status == NSS_STATUS_UNAVAIL && !any_service && errno != ENOENT)
+    /* This happens when we weren't able to use a service for reasons other
+       than the module not being found.  In such a case, we'd want to tell the
+       caller that errno has the real reason for failure.  */
     *h_errnop = NETDB_INTERNAL;
   else if (status != NSS_STATUS_SUCCESS && !any_service)
     /* We were not able to use any service.  */
diff --git a/sysdeps/posix/getaddrinfo.c b/sysdeps/posix/getaddrinfo.c
index ab135ad..7bb3ded 100644
--- a/sysdeps/posix/getaddrinfo.c
+++ b/sysdeps/posix/getaddrinfo.c
@@ -1036,7 +1036,15 @@ gaih_inet (const char *name, const struct gaih_service *service,
 			}
 		    }
 		  else
-		    status = NSS_STATUS_UNAVAIL;
+		    {
+		      status = NSS_STATUS_UNAVAIL;
+		      /* Could not load any of the lookup functions.  Indicate
+		         an internal error if the failure was due to a system
+			 error other than the file not being found.  We use the
+			 errno from the last failed callback.  */
+		      if (errno != 0 && errno != ENOENT)
+			__set_h_errno (NETDB_INTERNAL);
+		    }
 		}
 
 	      if (nss_next_action (nip, status) == NSS_ACTION_RETURN)
@@ -1050,7 +1058,7 @@ gaih_inet (const char *name, const struct gaih_service *service,
 
 	  _res.options |= old_res_options & RES_USE_INET6;
 
-	  if (status == NSS_STATUS_UNAVAIL)
+	  if (h_errno == NETDB_INTERNAL)
 	    {
 	      result = GAIH_OKIFUNSPEC | -EAI_SYSTEM;
 	      goto free_and_return;