From: Ludwig Nussel <ludwig.nussel@suse.de>
Date: Fri, 20 May 2011 15:38:46 +0200
Subject: optionally warn if nss-myhostname is called

---
 configure.ac                        | 11 +++++++++++
 src/nss-myhostname/nss-myhostname.c | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/configure.ac b/configure.ac
index 5173783..e58d694 100644
--- a/configure.ac
+++ b/configure.ac
@@ -714,6 +714,17 @@ if test "x$enable_myhostname" != "xno"; then
 fi
 AM_CONDITIONAL(HAVE_MYHOSTNAME, [test "$have_myhostname" = "yes"])
 
+if test "x$have_myhostname" != "xno"; then
+	AC_MSG_CHECKING([log warning messages for nss-myhostname])
+	AC_ARG_WITH(nss-my-hostname-warning, AS_HELP_STRING([--with-nss-my-hostname-warning], [log warning to syslog when nss-myhostname is called (default=no)]),[],[with_nss_my_hostname_warning=no])
+	AC_MSG_RESULT([$with_nss_my_hostname_warning])
+
+	if test x$with_nss_my_hostname_warning != xno; then
+		AC_CHECK_HEADERS([syslog.h])
+		AC_DEFINE([LOG_NSS_MY_HOSTNAME_WARNING],[1],[whether to log warning message for nss-myhostname])
+	fi
+fi
+
 # ------------------------------------------------------------------------------
 AC_ARG_WITH(firmware-path,
        AS_HELP_STRING([--with-firmware-path=DIR[[[:DIR[...]]]]],
diff --git a/src/nss-myhostname/nss-myhostname.c b/src/nss-myhostname/nss-myhostname.c
index 884eb99..dbd9a2d 100644
--- a/src/nss-myhostname/nss-myhostname.c
+++ b/src/nss-myhostname/nss-myhostname.c
@@ -30,6 +30,9 @@
 #include <net/if.h>
 #include <stdlib.h>
 #include <arpa/inet.h>
+#ifdef LOG_NSS_MY_HOSTNAME_WARNING
+#include <syslog.h>
+#endif
 
 #include "ifconf.h"
 #include "macro.h"
@@ -44,6 +47,10 @@
 #define LOCALADDRESS_IPV6 &in6addr_loopback
 #define LOOPBACK_INTERFACE "lo"
 
+#ifdef LOG_NSS_MY_HOSTNAME_WARNING
+static void warn(const char* hn);
+#endif
+
 enum nss_status _nss_myhostname_gethostbyname4_r(
                 const char *name,
                 struct gaih_addrtuple **pat,
@@ -115,6 +122,10 @@ enum nss_status _nss_myhostname_gethostbyname4_r(
                 return NSS_STATUS_NOTFOUND;
         }
 
+#ifdef LOG_NSS_MY_HOSTNAME_WARNING
+        warn(hn);
+#endif
+
         /* If this fails, n_addresses is 0. Which is fine */
         ifconf_acquire_addresses(&addresses, &n_addresses);
 
@@ -334,6 +345,10 @@ enum nss_status _nss_myhostname_gethostbyname3_r(
                 return NSS_STATUS_NOTFOUND;
         }
 
+#ifdef LOG_NSS_MY_HOSTNAME_WARNING
+        warn(hn);
+#endif
+
         return fill_in_hostent(hn, af, host, buffer, buflen, errnop, h_errnop, ttlp, canonp);
 }
 
@@ -429,6 +444,10 @@ found:
                 return NSS_STATUS_UNAVAIL;
         }
 
+#ifdef LOG_NSS_MY_HOSTNAME_WARNING
+        warn(hn);
+#endif
+
         return fill_in_hostent(hn, af, host, buffer, buflen, errnop, h_errnop, ttlp, NULL);
 
 }
@@ -448,3 +467,19 @@ enum nss_status _nss_myhostname_gethostbyaddr_r(
                         errnop, h_errnop,
                         NULL);
 }
+
+#ifdef LOG_NSS_MY_HOSTNAME_WARNING
+static void warn(const char* hn) {
+        if (strstr(program_invocation_short_name, "nscd")) {
+                syslog(LOG_WARNING,
+                        "Some application tried to resolve hostname \"%s\" which is not in DNS. Stop nscd to find out which one.\n",
+                        hn);
+        } else {
+                syslog(LOG_WARNING,
+                        "%s(%u) tried to resolve hostname \"%s\" which is not in DNS. This might be the reason for the delays you experience.\n",
+                        program_invocation_short_name,
+                        getpid(),
+                        hn);
+        }
+}
+#endif