Protect against updating hostname if we listen on loopback

pappl/dnssd-private.h

@@ -52,6 +52,7 @@ typedef void *_pappl_dns_sd_t;		// DNS-SD master reference
 extern const char	*_papplDNSSDCopyHostName(char *buffer, size_t bufsize) _PAPPL_PRIVATE;
 extern int		_papplDNSSDGetHostChanges(void) _PAPPL_PRIVATE;
 extern _pappl_dns_sd_t	_papplDNSSDInit(pappl_system_t *system) _PAPPL_PRIVATE;
+extern bool		_papplDNSSDIsLoopback(const char *name) _PAPPL_PRIVATE;
 extern void		_papplDNSSDLock(void) _PAPPL_PRIVATE;
 extern const char	*_papplDNSSDStrError(int error) _PAPPL_PRIVATE;
 extern void		_papplDNSSDUnlock(void) _PAPPL_PRIVATE;

pappl/dnssd.c

@@ -26,8 +26,13 @@
 
 static char		pappl_dns_sd_hostname[256] = "";
 					// Current DNS-SD hostname
+#ifdef HAVE_MDNSRESPONDER
 static int		pappl_dns_sd_hostname_changes = 0;
 					// Number of host name changes/collisions
+#elif defined(HAVE_AVAHI)
+static int		pappl_dns_sd_hostname_changes = -1;
+					// Number of host name changes/collisions
+#endif // HAVE_MDNSRESPONDER
 static pthread_mutex_t	pappl_dns_sd_hostname_mutex = PTHREAD_MUTEX_INITIALIZER;
 					// Host name mutex
 #ifdef HAVE_MDNSRESPONDER
@@ -49,7 +54,6 @@ static AvahiThreadedPoll *pappl_dns_sd_poll = NULL;
 //
 
 static void		dns_sd_geo_to_loc(const char *geo, unsigned char loc[16]);
-static bool		dns_sd_is_loopback(const char *name);
 #ifdef HAVE_MDNSRESPONDER
 static void DNSSD_API	dns_sd_hostname_callback(DNSServiceRef ref, DNSServiceFlags flags, uint32_t if_index, DNSServiceErrorType error, const char *fullname, uint16_t rrtype, uint16_t rrclass, uint16_t rdlen, const void *rdata, uint32_t ttl, void *context);
 static void DNSSD_API	dns_sd_printer_callback(DNSServiceRef sdRef, DNSServiceFlags flags, DNSServiceErrorType errorCode, const char *name, const char *regtype, const char *domain, pappl_printer_t *printer);
@@ -393,9 +397,9 @@ _papplPrinterRegisterDNSSDNoLock(
   papplLogPrinter(printer, PAPPL_LOGLEVEL_DEBUG, "Registering DNS-SD name '%s' on '%s'", printer->dns_sd_name, printer->system->hostname);
 
 #  ifdef HAVE_MDNSRESPONDER
-  if_index = dns_sd_is_loopback(system->hostname) ? kDNSServiceInterfaceIndexLocalOnly : kDNSServiceInterfaceIndexAny;
+  if_index = _papplDNSSDIsLoopback(system->hostname) ? kDNSServiceInterfaceIndexLocalOnly : kDNSServiceInterfaceIndexAny;
 #  else
-  if_index = dns_sd_is_loopback(system->hostname) ? if_nametoindex("lo") : AVAHI_IF_UNSPEC;
+  if_index = _papplDNSSDIsLoopback(system->hostname) ? if_nametoindex("lo") : AVAHI_IF_UNSPEC;
 #  endif // HAVE_MDNSRESPONDER
 
   // Get attributes and values for the TXT record...
@@ -952,9 +956,9 @@ _papplSystemRegisterDNSSDNoLock(
   papplLog(system, PAPPL_LOGLEVEL_DEBUG, "Registering DNS-SD name '%s' on '%s'", system->dns_sd_name, system->hostname);
 
 #  ifdef HAVE_MDNSRESPONDER
-  if_index = dns_sd_is_loopback(system->hostname) ? kDNSServiceInterfaceIndexLocalOnly : kDNSServiceInterfaceIndexAny;
+  if_index = _papplDNSSDIsLoopback(system->hostname) ? kDNSServiceInterfaceIndexLocalOnly : kDNSServiceInterfaceIndexAny;
 #  else
-  if_index = dns_sd_is_loopback(system->hostname) ? if_nametoindex("lo") : AVAHI_IF_UNSPEC;
+  if_index = _papplDNSSDIsLoopback(system->hostname) ? if_nametoindex("lo") : AVAHI_IF_UNSPEC;
 #  endif // HAVE_MDNSRESPONDER
 
   if (system->geo_location)
@@ -1479,13 +1483,16 @@ dns_sd_system_callback(
 
 
 //
-// 'dns_sd_is_loopback()' - Find out whether the string means
+// '_papplDNSSDIsLoopback()' - Find out whether the string means
 //                           localhost
 //
 
-static bool
-dns_sd_is_loopback(const char *name)
+bool
+_papplDNSSDIsLoopback(const char *name)
 {
+  if (!name)
+    return (false);
+
   if (!strcasecmp(name, "localhost"))
     return (true);
   else if (!strcmp(name, "127.0.0.1"))

pappl/system.c

@@ -652,7 +652,7 @@ papplSystemRun(pappl_system_t *system)	// I - System
       bool		force_dns_sd = system->dns_sd_host_changes != dns_sd_host_changes;
 					// Force re-registration?
 
-      if (force_dns_sd)
+      if (!_papplDNSSDIsLoopback(system->hostname) && force_dns_sd)
         _papplSystemSetHostNameNoLock(system, NULL);
 
       if (system->dns_sd_collision || force_dns_sd)