Make "register_tap_listener()" return NULL on success and a "GString *"

referring to a GString containing an error message on failure, and don't
have it print anything on failure.

If it fails, have its Tethereal-tap callers print an error message
before exiting, and have its Ethereal callers pop up a dialog box with
the error (except in cases where the failure is guaranteed not to be the
user's fault, and where we exit, in which case we just print an error
message before we exit).  In all cases, the error message includes the
text of the GString.

Fix a scanf format string in the DCE RPC statistics Ethereal tap, so
that it properly skips the comma before the filter string.

Fix some Ethereal error messages not to say "tethereal".

svn path=/trunk/; revision=7542

20 files changed, 149 insertions, 85 deletions

diff --git a/gtk/dcerpc_stat.c b/gtk/dcerpc_stat.c
index ab455ee151..226f7fbbc4 100644
--- a/gtk/dcerpc_stat.c
+++ b/gtk/dcerpc_stat.c
@@ -1,7 +1,7 @@
 /* dcerpc_stat.c
  * dcerpc_stat   2002 Ronnie Sahlberg
  *
- * $Id: dcerpc_stat.c,v 1.5 2003/04/23 05:37:22 guy Exp $
+ * $Id: dcerpc_stat.c,v 1.6 2003/04/23 08:20:05 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -22,8 +22,9 @@
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  */
 
-/* This module provides rpc call/reply RTT statistics to tethereal.
- * It is only used by tethereal and not ethereal
+/* This module provides rpc call/reply RTT statistics to ethereal,
+ * and displays them graphically.
+ * It is only used by ethereal and not tethereal
  *
  * It serves as an example on how to use the tap api.
  */
@@ -262,8 +263,9 @@ gtk_dcerpcstat_init(char *optarg)
 	int major, minor;
 	int pos=0;
         char *filter=NULL;
+        GString *error_string;
 
-	if(sscanf(optarg,"dcerpc,rtt,%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x,%d.%d%n", &d1,&d2,&d3,&d40,&d41,&d42,&d43,&d44,&d45,&d46,&d47,&major,&minor,&pos)==13){
+	if(sscanf(optarg,"dcerpc,rtt,%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x,%d.%d,%n", &d1,&d2,&d3,&d40,&d41,&d42,&d43,&d44,&d45,&d46,&d47,&major,&minor,&pos)==13){
 		uuid.Data1=d1;
 		uuid.Data2=d2;
 		uuid.Data3=d3;
@@ -281,7 +283,7 @@ gtk_dcerpcstat_init(char *optarg)
 			filter=NULL;
 		}
 	} else {
-		fprintf(stderr, "tethereal: invalid \"-z dcerpc,rtt,<uuid>,<major version>.<minor version>[,<filter>]\" argument\n");
+		fprintf(stderr, "ethereal: invalid \"-z dcerpc,rtt,<uuid>,<major version>.<minor version>[,<filter>]\" argument\n");
 		exit(1);
 	}
 
@@ -290,7 +292,7 @@ gtk_dcerpcstat_init(char *optarg)
 	rs->prog=dcerpc_get_proto_name(&uuid, (minor<<8)|(major&0xff) );
 	if(!rs->prog){
 		g_free(rs);
-		fprintf(stderr,"tethereal: dcerpcstat_init() Protocol with uuid:%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x v%d.%d not supported\n",uuid.Data1,uuid.Data2,uuid.Data3,uuid.Data4[0],uuid.Data4[1],uuid.Data4[2],uuid.Data4[3],uuid.Data4[4],uuid.Data4[5],uuid.Data4[6],uuid.Data4[7],major,minor);
+		fprintf(stderr,"ethereal: dcerpcstat_init() Protocol with uuid:%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x v%d.%d not supported\n",uuid.Data1,uuid.Data2,uuid.Data3,uuid.Data4[0],uuid.Data4[1],uuid.Data4[2],uuid.Data4[3],uuid.Data4[4],uuid.Data4[5],uuid.Data4[6],uuid.Data4[7],major,minor);
 		exit(1);
 	}
 	procs=dcerpc_get_proto_sub_dissector(&uuid, (minor<<8)|(major&0xff) );
@@ -402,11 +404,11 @@ gtk_dcerpcstat_init(char *optarg)
 	gtk_widget_show(rs->table);
 
 
-	if(register_tap_listener("dcerpc", rs, filter, (void*)dcerpcstat_reset, (void*)dcerpcstat_packet, (void*)dcerpcstat_draw)){
-		char str[256];
+	error_string=register_tap_listener("dcerpc", rs, filter, (void*)dcerpcstat_reset, (void*)dcerpcstat_packet, (void*)dcerpcstat_draw);
+	if(error_string){
 		/* error, we failed to attach to the tap. clean up */
-		snprintf(str,255,"Could not attach to tap using filter:%s",filter?filter:"");
-		simple_dialog(ESD_TYPE_WARN, NULL, str);
+		simple_dialog(ESD_TYPE_WARN, NULL, error_string->str);
+		g_string_free(error_string, TRUE);
 		g_free(rs->procedures);
 		g_free(rs);
 		return;
diff --git a/gtk/io_stat.c b/gtk/io_stat.c
index ccb7238a3f..649ee04321 100644
--- a/gtk/io_stat.c
+++ b/gtk/io_stat.c
@@ -1,7 +1,7 @@
 /* io_stat.c
  * io_stat   2002 Ronnie Sahlberg
  *
- * $Id: io_stat.c,v 1.20 2003/04/23 05:37:22 guy Exp $
+ * $Id: io_stat.c,v 1.21 2003/04/23 08:20:05 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -39,6 +39,7 @@
 
 #include <gtk/gtk.h>
 #include "gtkglobals.h"
+#include "menu.h"
 #include "epan/epan_dissect.h"
 #include "epan/packet_info.h"
 #include "../tap.h"
@@ -824,6 +825,7 @@ gtk_iostat_init(char *optarg _U_)
 		{0,	0x0000,	0x0000,	0xffff},
 		{0,	0xffff,	0x5000,	0xffff}
 	};
+	GString *error_string;
 
 	io=g_malloc(sizeof(io_stat_t));
 	io->needs_redraw=1;
@@ -871,7 +873,11 @@ gtk_iostat_init(char *optarg _U_)
 		io->graphs[i].filter_bt=NULL;
 	}
 
-	if(register_tap_listener("frame", &io->graphs[0], NULL, gtk_iostat_reset, gtk_iostat_packet, gtk_iostat_draw)){
+	error_string=register_tap_listener("frame", &io->graphs[0], NULL, gtk_iostat_reset, gtk_iostat_packet, gtk_iostat_draw);
+	if(error_string){
+		fprintf(stderr, "ethereal: Can't attach io_stat tap: %s\n",
+		    error_string->str);
+		g_string_free(error_string, TRUE);
 		g_free(io->graphs[0].counts);
 		io->graphs[0].counts=NULL;
 		io->graphs[0].display=0;
diff --git a/gtk/main.c b/gtk/main.c
index 4c3fd87588..a079fdea60 100644
--- a/gtk/main.c
+++ b/gtk/main.c
@@ -1,6 +1,6 @@
 /* main.c
  *
- * $Id: main.c,v 1.289 2003/04/23 03:51:03 guy Exp $
+ * $Id: main.c,v 1.290 2003/04/23 08:20:05 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -1504,7 +1504,7 @@ main(int argc, char *argv[])
       else if (strcmp(argv[2], "protocols") == 0)
         proto_registrar_dump_protocols();
       else {
-        fprintf(stderr, "tethereal: Invalid \"%s\" option for -G flag\n",
+        fprintf(stderr, "ethereal: Invalid \"%s\" option for -G flag\n",
                 argv[2]);
         exit(1);
       }
diff --git a/gtk/mgcp_stat.c b/gtk/mgcp_stat.c
index 1cb9b1052d..18119e5a75 100644
--- a/gtk/mgcp_stat.c
+++ b/gtk/mgcp_stat.c
@@ -2,7 +2,7 @@
  * mgcp-statistics for ethereal
  * Copyright 2003 Lars Roland
  *
- * $Id: mgcp_stat.c,v 1.3 2003/04/23 05:37:22 guy Exp $
+ * $Id: mgcp_stat.c,v 1.4 2003/04/23 08:20:05 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -35,6 +35,7 @@
 
 #include <gtk/gtk.h>
 #include <string.h>
+#include "menu.h"
 #include "../epan/packet_info.h"
 #include "../tap.h"
 #include "../epan/value_string.h"
@@ -278,6 +279,7 @@ gtk_mgcpstat_init(char *optarg)
 	GtkWidget *stat_label;
 	GtkWidget *filter_label;
 	char filter_string[256];
+	GString *error_string;
 
 	if(!strncmp(optarg,"mgcp,rtd,",9)){
 		filter=optarg+9;
@@ -324,11 +326,10 @@ gtk_mgcpstat_init(char *optarg)
 
 	gtk_widget_show(ms->table);
 
-	if(register_tap_listener("mgcp", ms, filter, mgcpstat_reset, mgcpstat_packet, mgcpstat_draw)){
-		char str[256];
-		/* error, we failed to attach to the tap. clean up */
-		snprintf(str,255,"Could not attach to tap using filter:%s",filter?filter:"");
-		simple_dialog(ESD_TYPE_WARN, NULL, str);
+	error_string=register_tap_listener("mgcp", ms, filter, mgcpstat_reset, mgcpstat_packet, mgcpstat_draw);
+	if(error_string){
+		simple_dialog(ESD_TYPE_WARN, NULL, error_string->str);
+		g_string_free(error_string, TRUE);
 		g_free(ms->filter);
 		g_free(ms);
 		return;
diff --git a/gtk/rpc_progs.c b/gtk/rpc_progs.c
index f54d68881b..ac444d9898 100644
--- a/gtk/rpc_progs.c
+++ b/gtk/rpc_progs.c
@@ -1,7 +1,7 @@
 /* rpc_progs.c
  * rpc_progs   2002 Ronnie Sahlberg
  *
- * $Id: rpc_progs.c,v 1.8 2003/04/23 05:37:23 guy Exp $
+ * $Id: rpc_progs.c,v 1.9 2003/04/23 08:20:05 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -33,6 +33,7 @@
 #endif
 
 #include <gtk/gtk.h>
+#include "menu.h"
 #include "epan/packet_info.h"
 #include "tap.h"
 #include "../register.h"
@@ -320,6 +321,7 @@ gtk_rpcprogs_init(char *optarg _U_)
 	GtkWidget *vbox;
 	GtkWidget *stat_label;
 	GtkWidget *tmp;
+	GString *error_string;
 
 	if(win){
 		gdk_window_raise(win->window);
@@ -377,8 +379,11 @@ gtk_rpcprogs_init(char *optarg _U_)
 	
 	gtk_widget_show(table);
 
-	if(register_tap_listener("rpc", win, NULL, (void*)rpcprogs_reset, (void*)rpcprogs_packet, (void*)rpcprogs_draw)){
-		fprintf(stderr, "ethereal: gtk_rpcprogs_init() failed to register tap\n");
+	error_string=register_tap_listener("rpc", win, NULL, (void*)rpcprogs_reset, (void*)rpcprogs_packet, (void*)rpcprogs_draw);
+	if(error_string){
+		fprintf(stderr, "ethereal: Couldn't register rpc,programs tap: %s\n",
+		    error_string->str);
+		g_string_free(error_string, TRUE);
 		exit(1);
 	}
 
diff --git a/gtk/rpc_stat.c b/gtk/rpc_stat.c
index 3800c32f32..43490eb71a 100644
--- a/gtk/rpc_stat.c
+++ b/gtk/rpc_stat.c
@@ -1,7 +1,7 @@
 /* rpc_stat.c
  * rpc_stat   2002 Ronnie Sahlberg
  *
- * $Id: rpc_stat.c,v 1.8 2003/04/23 05:37:23 guy Exp $
+ * $Id: rpc_stat.c,v 1.9 2003/04/23 08:20:05 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -283,6 +283,7 @@ gtk_rpcstat_init(char *optarg)
 	GtkWidget *tmp;
 	int program, version, pos;
 	char *filter=NULL;
+	GString *error_string;
 
 	pos=0;
 	if(sscanf(optarg,"rpc,rtt,%d,%d,%n",&program,&version,&pos)==2){
@@ -397,11 +398,10 @@ gtk_rpcstat_init(char *optarg)
 
 	gtk_widget_show(rs->table);
 
-	if(register_tap_listener("rpc", rs, filter, (void*)rpcstat_reset, (void*)rpcstat_packet, (void*)rpcstat_draw)){
-		char str[256];
-		/* error, we failed to attach to the tap. clean up */
-		snprintf(str,255,"Could not attach to tap using filter:%s",filter?filter:"");
-		simple_dialog(ESD_TYPE_WARN, NULL, str);
+	error_string=register_tap_listener("rpc", rs, filter, (void*)rpcstat_reset, (void*)rpcstat_packet, (void*)rpcstat_draw);
+	if(error_string){
+		simple_dialog(ESD_TYPE_WARN, NULL, error_string->str);
+		g_string_free(error_string, TRUE);
 		g_free(rs->procedures);
 		g_free(rs);
 		return;
diff --git a/gtk/smb_stat.c b/gtk/smb_stat.c
index 51e70a2e6f..29ff8e5832 100644
--- a/gtk/smb_stat.c
+++ b/gtk/smb_stat.c
@@ -1,7 +1,7 @@
 /* smb_stat.c
  * smb_stat   2003 Ronnie Sahlberg
  *
- * $Id: smb_stat.c,v 1.4 2003/04/23 05:37:23 guy Exp $
+ * $Id: smb_stat.c,v 1.5 2003/04/23 08:20:06 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -376,6 +376,7 @@ gtk_smbstat_init(char *optarg)
 	GtkWidget *stat_label;
 	GtkWidget *filter_label;
 	char filter_string[256];
+	GString *error_string;
 
 	if(!strncmp(optarg,"smb,rtt,",8)){
 		filter=optarg+8;
@@ -472,11 +473,10 @@ gtk_smbstat_init(char *optarg)
 
 	gtk_widget_show(ss->table);
 
-	if(register_tap_listener("smb", ss, filter, smbstat_reset, smbstat_packet, smbstat_draw)){
-		char str[256];
-		/* error, we failed to attach to the tap. clean up */
-		snprintf(str,255,"Could not attach to tap using filter:%s\nMaybe the filter string is invalid?",filter?filter:"");
-		simple_dialog(ESD_TYPE_WARN, NULL, str);
+	error_string=register_tap_listener("smb", ss, filter, smbstat_reset, smbstat_packet, smbstat_draw);
+	if(error_string){
+		simple_dialog(ESD_TYPE_WARN, NULL, error_string->str);
+		g_string_free(error_string, TRUE);
 		g_free(ss->filter);
 		g_free(ss);
 		return;
diff --git a/gtk/tap_rtp.c b/gtk/tap_rtp.c
index b4f51b1662..825ed1c827 100644
--- a/gtk/tap_rtp.c
+++ b/gtk/tap_rtp.c
@@ -1,7 +1,7 @@
 /*
  * tap_rtp.c
  *
- * $Id: tap_rtp.c,v 1.9 2003/04/23 03:51:03 guy Exp $
+ * $Id: tap_rtp.c,v 1.10 2003/04/23 08:20:06 guy Exp $
  *
  * RTP analysing addition for ethereal
  *
@@ -1621,6 +1621,7 @@ static void rtp_analyse_cb(GtkWidget *w _U_, gpointer data _U_)
   gint err;
   gboolean frame_matched;
   frame_data *fdata;
+  GString *error_string;
 
   /* There's already a "Display Options" dialog box; reactivate it. */
   if (rtp_w != NULL) {
@@ -1694,9 +1695,11 @@ static void rtp_analyse_cb(GtkWidget *w _U_, gpointer data _U_)
 	  edt->pi.srcport
 	  );
 /* XXX compiler warning:passing arg 5 of `register_tap_listener' from incompatible pointer type */
-  if(register_tap_listener("rtp", rs, filter_text, rtp_reset, rtp_packet, rtp_draw)){
-	printf("ethereal: rtp_init() failed to attach the tap.\n");
+  error_string = register_tap_listener("rtp", rs, filter_text, rtp_reset, rtp_packet, rtp_draw);
+  if (error_string != NULL) {
+	simple_dialog(ESD_TYPE_WARN, NULL, error_string->str);
 	/* XXX is this enough or do I have to free anything else? */
+	g_string_free(error_string, TRUE);
 	g_free(rs);
 	exit(1);
   }
diff --git a/packet-smb-sidsnooping.c b/packet-smb-sidsnooping.c
index 226431694a..270968deba 100644
--- a/packet-smb-sidsnooping.c
+++ b/packet-smb-sidsnooping.c
@@ -2,7 +2,7 @@
  * Routines for snooping SID to name mappings
  * Copyright 2003, Ronnie Sahlberg
  *
- * $Id: packet-smb-sidsnooping.c,v 1.2 2003/03/25 19:52:56 guy Exp $
+ * $Id: packet-smb-sidsnooping.c,v 1.3 2003/04/23 08:20:01 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -162,6 +162,7 @@ static void
 sid_snooping_init(void)
 {
 	header_field_info *hfi;
+	GString *error_string;
 
 	if(lsa_QueryInfoPolicy_l3_reply_flag){
 		remove_tap_listener(lsa_QueryInfoPolicy_l3_reply_flag);
@@ -209,10 +210,13 @@ sid_snooping_init(void)
 
 
 
-	if(register_tap_listener("dcerpc", lsa_QueryInfoPolicy_l3_reply, "dcerpc.pkt_type==2 and lsa.opnum==7 and lsa.info.level==3 and lsa.domain and smb.sid", NULL, lsa_QueryInfoPolicy_l3_reply, NULL)){
+	error_string=register_tap_listener("dcerpc", lsa_QueryInfoPolicy_l3_reply, "dcerpc.pkt_type==2 and lsa.opnum==7 and lsa.info.level==3 and lsa.domain and smb.sid", NULL, lsa_QueryInfoPolicy_l3_reply, NULL);
+	if(error_string){
 		/* error, we failed to attach to the tap. clean up */
 
-		fprintf(stderr,"tethereal: proto_reg_handoff_smb_sidsnooping()/lsa_QueryInfoPolicy_l3_reply failed to attach to tap.\n");
+		fprintf(stderr, "tethereal: Couldn't register proto_reg_handoff_smb_sidsnooping()/lsa_QueryInfoPolicy_l3_reply tap: %s\n",
+		    error_string->str);
+		g_string_free(error_string, TRUE);
 		exit(1);
 	}
 	lsa_QueryInfoPolicy_l3_reply_flag=lsa_QueryInfoPolicy_l3_reply;
diff --git a/tap-dcerpcstat.c b/tap-dcerpcstat.c
index 96b155fb44..df5e48c473 100644
--- a/tap-dcerpcstat.c
+++ b/tap-dcerpcstat.c
@@ -1,7 +1,7 @@
 /* tap-dcerpcstat.c
  * dcerpcstat   2002 Ronnie Sahlberg
  *
- * $Id: tap-dcerpcstat.c,v 1.4 2003/04/23 03:50:59 guy Exp $
+ * $Id: tap-dcerpcstat.c,v 1.5 2003/04/23 08:20:01 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -197,6 +197,7 @@ dcerpcstat_init(char *optarg)
 	int major, minor;
 	int pos=0;
         char *filter=NULL;
+        GString *error_string;
     
 	if(sscanf(optarg,"dcerpc,rtt,%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x,%d.%d%n", &d1,&d2,&d3,&d40,&d41,&d42,&d43,&d44,&d45,&d46,&d47,&major,&minor,&pos)==13){
 		uuid.Data1=d1;
@@ -263,13 +264,16 @@ dcerpcstat_init(char *optarg)
 		rs->procedures[i].tot.nsecs=0;
 	}
 
-	if(register_tap_listener("dcerpc", rs, filter, NULL, dcerpcstat_packet, dcerpcstat_draw)){
+	error_string=register_tap_listener("dcerpc", rs, filter, NULL, dcerpcstat_packet, dcerpcstat_draw);
+	if(error_string){
 		/* error, we failed to attach to the tap. clean up */
 		g_free(rs->procedures);
 		g_free(rs->filter);
 		g_free(rs);
 
-		fprintf(stderr,"tethereal: dcerpcstat_init() failed to attach to tap.\n");
+		fprintf(stderr, "tethereal: Couldn't register dcerpc,rtt tap: %s\n",
+		    error_string->str);
+		g_string_free(error_string, TRUE);
 		exit(1);
 	}
 }
diff --git a/tap-iostat.c b/tap-iostat.c
index 07f10717dc..7638d4aba8 100644
--- a/tap-iostat.c
+++ b/tap-iostat.c
@@ -1,7 +1,7 @@
 /* tap-iostat.c
  * iostat   2002 Ronnie Sahlberg
  *
- * $Id: tap-iostat.c,v 1.5 2003/04/23 03:50:59 guy Exp $
+ * $Id: tap-iostat.c,v 1.6 2003/04/23 08:20:01 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -220,6 +220,8 @@ iostat_draw(io_stat_item_t *mit)
 static void
 register_io_tap(io_stat_t *io, int i, char *filter)
 {
+	GString *error_string;
+
 	io->items[i].prev=&io->items[i];
 	io->items[i].next=NULL;
 	io->items[i].parent=io;
@@ -228,10 +230,13 @@ register_io_tap(io_stat_t *io, int i, char *filter)
 	io->items[i].bytes=0;
 	io->filters[i]=filter;
 
-	if(register_tap_listener("frame", &io->items[i], filter, NULL, (void*)iostat_packet, i?NULL:(void*)iostat_draw)){
+	error_string=register_tap_listener("frame", &io->items[i], filter, NULL, (void*)iostat_packet, i?NULL:(void*)iostat_draw);
+	if(error_string){
 		g_free(io->items);
 		g_free(io);
-		fprintf(stderr,"tethereal: iostat_init() failed to attach tap\n");
+		fprintf(stderr, "tethereal: Couldn't register io,stat tap: %s\n",
+		    error_string->str);
+		g_string_free(error_string, TRUE);
 		exit(1);
 	}
 }
diff --git a/tap-iousers.c b/tap-iousers.c
index 95aeb7e541..7fdd50ae3e 100644
--- a/tap-iousers.c
+++ b/tap-iousers.c
@@ -1,7 +1,7 @@
 /* tap-iousers.c
  * iostat   2003 Ronnie Sahlberg
  *
- * $Id: tap-iousers.c,v 1.5 2003/04/23 03:50:59 guy Exp $
+ * $Id: tap-iousers.c,v 1.6 2003/04/23 08:20:01 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -383,6 +383,7 @@ iousers_init(char *optarg)
 	char *tap_type;
 	static int (*packet_func)(io_users_t *, packet_info *, epan_dissect_t *, void *);
 	io_users_t *iu=NULL;
+	GString *error_string;
 
 	if(!strncmp(optarg,"io,users,eth",12)){
 		if(optarg[12]==','){
@@ -445,12 +446,15 @@ iousers_init(char *optarg)
 		iu->filter=NULL;
 	}
 
-	if(register_tap_listener(tap_type, iu, filter, NULL, (void*)packet_func, (void*)iousers_draw)){
+	error_string=register_tap_listener(tap_type, iu, filter, NULL, (void*)packet_func, (void*)iousers_draw);
+	if(error_string){
 		if(iu->items){
 			g_free(iu->items);
 		}
 		g_free(iu);
-		fprintf(stderr,"tethereal: iousers_init() failed to attach tap\n");
+		fprintf(stderr, "tethereal: Couldn't register io,users tap: %s\n",
+		    error_string->str);
+		g_string_free(error_string, TRUE);
 		exit(1);
 	}
 
diff --git a/tap-mgcpstat.c b/tap-mgcpstat.c
index 8313b7f42b..193b2d5135 100644
--- a/tap-mgcpstat.c
+++ b/tap-mgcpstat.c
@@ -1,7 +1,7 @@
 /* tap-mgcpstat.c
  * mgcpstat   2003 Lars Roland
  *
- * $Id: tap-mgcpstat.c,v 1.5 2003/04/23 03:50:59 guy Exp $
+ * $Id: tap-mgcpstat.c,v 1.6 2003/04/23 08:20:01 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -186,7 +186,7 @@ mgcpstat_init(char *optarg)
 	mgcpstat_t *ms;
 	int i;
 	char *filter=NULL;
-
+	GString *error_string;
 
 	if(!strncmp(optarg,"mgcp,rtd,",9)){
 		filter=optarg+9;
@@ -216,12 +216,15 @@ mgcpstat_init(char *optarg)
 	ms->req_dup_num=0;
 	ms->rsp_dup_num=0;
 
-	if(register_tap_listener("mgcp", ms, filter, NULL, mgcpstat_packet, mgcpstat_draw)){
+	error_string=register_tap_listener("mgcp", ms, filter, NULL, mgcpstat_packet, mgcpstat_draw);
+	if(error_string){
 		/* error, we failed to attach to the tap. clean up */
 		g_free(ms->filter);
 		g_free(ms);
 
-		fprintf(stderr,"tethereal: mgcpstat_init() failed to attach to tap.\n");
+		fprintf(stderr, "tethereal: Couldn't register mgcp,rtd tap: %s\n",
+		    error_string->str);
+		g_string_free(error_string, TRUE);
 		exit(1);
 	}
 }
diff --git a/tap-protocolinfo.c b/tap-protocolinfo.c
index bdc88e8a48..c2025a3ae8 100644
--- a/tap-protocolinfo.c
+++ b/tap-protocolinfo.c
@@ -1,7 +1,7 @@
 /* tap-protocolinfo.c
  * protohierstat   2002 Ronnie Sahlberg
  *
- * $Id: tap-protocolinfo.c,v 1.2 2003/04/23 03:50:59 guy Exp $
+ * $Id: tap-protocolinfo.c,v 1.3 2003/04/23 08:20:01 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -77,6 +77,7 @@ protocolinfo_init(char *optarg)
 	char *field=NULL;
 	char *filter=NULL;
 	header_field_info *hfi;
+	GString *error_string;
 
 	if(!strncmp("proto,colinfo,",optarg,14)){
 		filter=optarg+14;
@@ -106,14 +107,17 @@ protocolinfo_init(char *optarg)
 		rs->filter=NULL;
 	}
 
-	if(register_tap_listener("frame", rs, rs->filter, NULL, protocolinfo_packet, NULL)){
-		/* error, we failed to attach to the tap. clean up */
+	error_string=register_tap_listener("frame", rs, rs->filter, NULL, protocolinfo_packet, NULL);
+	if(error_string){
+		/* error, we failed to attach to the tap. complain and clean up */
+		fprintf(stderr, "tethereal: Couldn't register proto,colinfo tap: %s\n",
+		    error_string->str);
+		g_string_free(error_string, TRUE);
 		if(rs->filter){
 			g_free(rs->filter);
 		}
 		g_free(rs);
 
-		fprintf(stderr,"tethereal: protocolinfo_init() failed to attach to tap.\n");
 		exit(1);
 	}
 }
diff --git a/tap-protohierstat.c b/tap-protohierstat.c
index 00131f0910..1e04f028d8 100644
--- a/tap-protohierstat.c
+++ b/tap-protohierstat.c
@@ -1,7 +1,7 @@
 /* tap-protohierstat.c
  * protohierstat   2002 Ronnie Sahlberg
  *
- * $Id: tap-protohierstat.c,v 1.2 2003/04/23 03:50:59 guy Exp $
+ * $Id: tap-protohierstat.c,v 1.3 2003/04/23 08:20:02 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -171,6 +171,7 @@ protohierstat_init(char *optarg)
 	phs_t *rs;
 	int pos=0;
 	char *filter=NULL;
+	GString *error_string;
 
 	if(!strcmp("io,phs",optarg)){
 		filter="frame";
@@ -198,12 +199,15 @@ protohierstat_init(char *optarg)
 		rs->filter=NULL;
 	}
 
-	if(register_tap_listener("frame", rs, filter, NULL, protohierstat_packet, protohierstat_draw)){
+	error_string=register_tap_listener("frame", rs, filter, NULL, protohierstat_packet, protohierstat_draw);
+	if(error_string){
 		/* error, we failed to attach to the tap. clean up */
 		g_free(rs->filter);
 		g_free(rs);
 
-		fprintf(stderr,"tethereal: protohierstat_init() failed to attach to tap.\n");
+		fprintf(stderr, "tethereal: Couldn't register io,phs tap: %s\n",
+		    error_string->str);
+		g_string_free(error_string, TRUE);
 		exit(1);
 	}
 }
diff --git a/tap-rpcprogs.c b/tap-rpcprogs.c
index d544234388..7b6155a6fc 100644
--- a/tap-rpcprogs.c
+++ b/tap-rpcprogs.c
@@ -1,7 +1,7 @@
 /* tap-rpcprogs.c
  * rpcstat   2002 Ronnie Sahlberg
  *
- * $Id: tap-rpcprogs.c,v 1.4 2003/04/23 03:50:59 guy Exp $
+ * $Id: tap-rpcprogs.c,v 1.5 2003/04/23 08:20:02 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -222,13 +222,18 @@ rpcprogs_draw(void *dummy _U_)
 static void
 rpcprogs_init(char *optarg _U_)
 {
+	GString *error_string;
+
 	if(already_enabled){
 		return;
 	}
 	already_enabled=1;
 
-	if(register_tap_listener("rpc", NULL, NULL, NULL, rpcprogs_packet, rpcprogs_draw)){
-		fprintf(stderr,"tethereal: rpcprogs_init() failed to attach to tap.\n");
+	error_string=register_tap_listener("rpc", NULL, NULL, NULL, rpcprogs_packet, rpcprogs_draw);
+	if(error_string){
+		fprintf(stderr,"tethereal: Couldn't register rpc,programs tap: %s\n",
+		    error_string->str);
+		g_string_free(error_string, TRUE);
 		exit(1);
 	}
 }
diff --git a/tap-rpcstat.c b/tap-rpcstat.c
index e6e743c0e0..70f3b91f30 100644
--- a/tap-rpcstat.c
+++ b/tap-rpcstat.c
@@ -1,7 +1,7 @@
 /* tap-rpcstat.c
  * rpcstat   2002 Ronnie Sahlberg
  *
- * $Id: tap-rpcstat.c,v 1.7 2003/04/23 03:50:59 guy Exp $
+ * $Id: tap-rpcstat.c,v 1.8 2003/04/23 08:20:02 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -285,7 +285,7 @@ rpcstat_init(char *optarg)
 	int program, version;
 	int pos=0;
 	char *filter=NULL;
-
+	GString *error_string;
 
 	if(sscanf(optarg,"rpc,rtt,%d,%d,%n",&program,&version,&pos)==2){
 		if(pos){
@@ -343,13 +343,16 @@ rpcstat_init(char *optarg)
  *
  */
 
-	if(register_tap_listener("rpc", rs, filter, rpcstat_reset, rpcstat_packet, rpcstat_draw)){
+	error_string=register_tap_listener("rpc", rs, filter, rpcstat_reset, rpcstat_packet, rpcstat_draw);
+	if(error_string){
 		/* error, we failed to attach to the tap. clean up */
 		g_free(rs->procedures);
 		g_free(rs->filter);
 		g_free(rs);
 
-		fprintf(stderr,"tethereal: rpcstat_init() failed to attach to tap.\n");
+		fprintf(stderr, "tethereal: Couldn't register rpc,rtt tap: %s\n",
+		    error_string->str);
+		g_string_free(error_string, TRUE);
 		exit(1);
 	}
 }
diff --git a/tap-smbstat.c b/tap-smbstat.c
index 7683ac3a3f..cb42739494 100644
--- a/tap-smbstat.c
+++ b/tap-smbstat.c
@@ -1,7 +1,7 @@
 /* tap-smbstat.c
  * smbstat   2003 Ronnie Sahlberg
  *
- * $Id: tap-smbstat.c,v 1.2 2003/04/23 03:50:59 guy Exp $
+ * $Id: tap-smbstat.c,v 1.3 2003/04/23 08:20:02 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -247,7 +247,7 @@ smbstat_init(char *optarg)
 	smbstat_t *ss;
 	guint32 i;
 	char *filter=NULL;
-
+	GString *error_string;
 
 	if(!strncmp(optarg,"smb,rtt,",8)){
 		filter=optarg+8;
@@ -281,12 +281,15 @@ smbstat_init(char *optarg)
 		ss->trans2[i].tot.nsecs=0;
 	}
 
-	if(register_tap_listener("smb", ss, filter, NULL, smbstat_packet, smbstat_draw)){
+	error_string=register_tap_listener("smb", ss, filter, NULL, smbstat_packet, smbstat_draw);
+	if(error_string){
 		/* error, we failed to attach to the tap. clean up */
 		g_free(ss->filter);
 		g_free(ss);
 
-		fprintf(stderr,"tethereal: smbstat_init() failed to attach to tap.\n");
+		fprintf(stderr, "tethereal: Couldn't register smb,rtt tap: %s\n",
+		    error_string->str);
+		g_string_free(error_string, TRUE);
 		exit(1);
 	}
 }
diff --git a/tap.c b/tap.c
index 0a0b24b998..044956bb07 100644
--- a/tap.c
+++ b/tap.c
@@ -1,7 +1,7 @@
 /* tap.c
  * packet tap interface   2002 Ronnie Sahlberg
  *
- * $Id: tap.c,v 1.8 2002/11/28 20:28:28 guy Exp $
+ * $Id: tap.c,v 1.9 2003/04/23 08:20:02 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -335,29 +335,35 @@ find_tap_id(char *name)
 
 /* this function attaches the tap_listener to the named tap.
  * function returns :
- *  0: ok.
- * !0: error
-*/
-int
+ *     NULL: ok.
+ * non-NULL: error, return value points to GString containing error
+ *           message.
+ */
+GString *
 register_tap_listener(char *tapname, void *tapdata, char *fstring, tap_reset_cb reset, tap_packet_cb packet, tap_draw_cb draw)
 {
 	tap_listener_t *tl;
 	int tap_id;
+	GString *error_string;
 
 	tap_id=find_tap_id(tapname);
 	if(!tap_id){
-		fprintf(stderr, "tap not found\n");
-		exit(10);
+		error_string = g_string_new("");
+		g_string_sprintf(error_string, "Tap %s not found", tapname);
+		return error_string;
 	}
 
 	tl=g_malloc(sizeof(tap_listener_t));
 	tl->code=NULL;
 	tl->needs_redraw=1;
 	if(fstring){
-		if(!dfilter_compile(fstring ,&tl->code)){
+		if(!dfilter_compile(fstring, &tl->code)){
+			error_string = g_string_new("");
+			g_string_sprintf(error_string,
+			    "Filter \"%s\" is invalid - %s",
+			    fstring, dfilter_error_msg);
 			g_free(tl);
-			fprintf(stderr,"register_tap_listener(): %s\n", dfilter_error_msg);
-			return 1;
+			return error_string;
 		} else {
 			num_tap_filters++;
 		}
@@ -372,7 +378,7 @@ register_tap_listener(char *tapname, void *tapdata, char *fstring, tap_reset_cb
 
 	tap_listener_queue=tl;
 
-	return 0;
+	return NULL;
 }
 
 /* this function removes a tap listener
diff --git a/tap.h b/tap.h
index 0677fc8b5b..aba541f47c 100644
--- a/tap.h
+++ b/tap.h
@@ -1,7 +1,7 @@
 /* tap.h
  * packet tap interface   2002 Ronnie Sahlberg
  *
- * $Id: tap.h,v 1.7 2003/03/06 19:04:28 guy Exp $
+ * $Id: tap.h,v 1.8 2003/04/23 08:20:02 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -42,7 +42,9 @@ extern void tap_queue_init(epan_dissect_t *edt);
 extern void tap_push_tapped_queue(epan_dissect_t *edt);
 extern void reset_tap_listeners(void);
 extern void draw_tap_listeners(gboolean draw_all);
-extern int register_tap_listener(char *tapname, void *tapdata, char *fstring, tap_reset_cb tap_reset, tap_packet_cb tap_packet, tap_draw_cb tap_draw);
+extern GString *register_tap_listener(char *tapname, void *tapdata,
+    char *fstring, tap_reset_cb tap_reset, tap_packet_cb tap_packet,
+    tap_draw_cb tap_draw);
 extern void remove_tap_listener(void *tapdata);
 
 #endif