FreeTDS Development Group

[James Cameron <james.cameron AT hp.com>]

I'm yet to understand exactly how Casey's environment led to a failure
to report hostname resolution followed by a bogus IP address being used
... I've asked them for more detail.

On Fri, 2002-08-09 at 09:09, Brian Bruns wrote:
> I'm going to take part of the blame for this as well.  Our reporting of 
> hostname resolution problems needs to be much better.  I'm not sure when I 
> can get to rolling up a patch, anyone else up for it?

I've changed the code to report the failure of gethostbyname() to stderr
and the TDSDUMP log.  Here are the changes I'm proposing.  I haven't
committed them yet.  Could I have a review please?

diff -u -r1.108 ChangeLog
--- ChangeLog   8 Aug 2002 04:33:55 -0000       1.108
+++ ChangeLog   9 Aug 2002 01:57:16 -0000
@@ -1,3 +1,12 @@
+Fri Aug  9 11:56:01 2002  James Cameron  <quozl AT us.netrek.org>
+
+       * src/tds/config.c (lookup_host): report failure of
gethostbyname
+       to stderr and TDSDUMP log, and return a null string as result.
+
+       * src/tds/threadsafe.c (tds_gethostbyname_r): adjust the
+       non-reentrant version of the code to return h_errno now that it
is
+       required by lookup_host().
+
 Thu Aug  8 00:13:30 EDT 2002   JK Lowden <jklowden AT schemamania.org>
        + include/tds.h.in      tdsmoney now a union of TDS_INT8 and
TDS_OLD_MONEY
        + src/tds/convert.c     reinstituted numeric-based money
handling.  



diff -u -r1.18 config.c
--- src/tds/config.c    7 Jul 2002 04:33:15 -0000       1.18
+++ src/tds/config.c    9 Aug 2002 01:57:30 -0000
@@ -569,8 +569,32 @@
       This call take a while and is useless for an ip address.
       mlilback 3/2/02 */
    ip_addr = inet_addr(servername);
-   if (ip_addr == INADDR_NONE)
+   if (ip_addr == INADDR_NONE) {
       host = tds_gethostbyname_r(servername, &result, buffer, buflen,
&h_errnop);
+      /* check result of gethostbyname and propogate any failure */
+      if (host == NULL) {
+         char *reason = "unknown";
+         switch (h_errnop) {
+         case HOST_NOT_FOUND:
+            reason = "specified name is unknown";
+            break;
+         case NO_ADDRESS:
+         case NO_DATA:
+            reason = "name is valid but has no IP address";
+            break;
+         case NO_RECOVERY:
+            reason = "non-recoverable name server error occurred";
+            break;
+         case TRY_AGAIN:
+            reason = "temporary error on authoritative name server";
+            break;
+         }
+        fprintf(stderr, "src/tds/config.c: lookup_host: gethostbyname:
%s, %s\n", servername, rea
son);
+         tdsdump_log(TDS_DBG_ERROR, "%L gethostbyname(%s) failed with
\"%s\".\n",servername,reaso
n);
+         ip[0] = '\0';
+         return;
+      }
+   }
 
 #ifndef NOREVERSELOOKUPS
 /* froy AT singleentry.com 12/21/2000 */




diff -u -r1.5 threadsafe.c
--- src/tds/threadsafe.c        9 Jul 2002 01:55:05 -0000       1.5
+++ src/tds/threadsafe.c        9 Aug 2002 01:57:45 -0000
@@ -78,8 +78,10 @@
 tds_gethostbyname_r(const char *servername, struct hostent *result,
char *buffer, int buflen, int
 *h_errnop)
 {
 #ifndef _REENTRANT
-       return gethostbyname(servername);
-
+       extern int h_errno;
+       struct hostent *result = gethostbyname(servername);
+       h_errnop = &h_errno;
+       return result;
 #else
 
 #if defined(HAVE_FUNC_GETHOSTBYNAME_R_6)


-- 
James Cameron                                     (james.cameron AT hp.com)

http://quozl.linux.org.au/         (or)         http://quozl.netrek.org/