Windows: Avoid unnecessary DNS lookups

Windows will attempt to open connections to a broad
range of pipe service (share) names which do not contain
a dot in them.  Attempts to search for these names as
cell names in DNS result in timeouts and sluggish behavior
when browsing \\AFS in the Explorer Shell.

To avoid this problem, do not perform a DNS lookup for a
cellname that doesn't not contain a dot in it.

LICENSE MIT

Reviewed-on: http://gerrit.openafs.org/302
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>

diff --git a/src/WINNT/afsd/cm_config.c b/src/WINNT/afsd/cm_config.c
index eaaba81b325d4535380f08050325da1b4d692c12..e525a1790e6cb9378478d809ac58a9fe1a94c785 100644 (file)
--- a/src/WINNT/afsd/cm_config.c
+++ b/src/WINNT/afsd/cm_config.c
@@ -689,8 +689,16 @@ long cm_SearchCellByDNS(char *cellNamep, char *newCellNamep, int *ttl,
 #ifdef CELLSERV_DEBUG
     osi_Log1(afsd_logp,"SearchCellDNS-Doing search for [%s]", osi_LogSaveString(afsd_logp,cellNamep));
 #endif
-    if ( IsWindowsModule(cellNamep) )
+    /*
+     * Do not perform a DNS lookup if the name is
+     * either a well-known Windows DLL or directory,
+     * or if the name does not contain a top-level
+     * domain.
+     */
+    if ( IsWindowsModule(cellNamep) ||
+         cm_FsStrChr(cellNamep, '.') == NULL)
        return -1;
+
     rc = getAFSServer(cellNamep, cellHostAddrs, cellHostNames, ipRanks, &numServers, ttl);
     if (rc == 0 && numServers > 0) {     /* found the cell */
         for (i = 0; i < numServers; i++) {