Get rid of NO_INTERFACES_FOUND - it's not an error.

It just means "pcap didn't give me any interfaces, and didn't report an
error".  Hopefully, in the future, there will be pcap APIs that
distinguish between the (admittedly unlikely, these days) case of "there
really *are* no interfaces on which *anybody* can capture" and "you
don't have sufficient permission to capture", and we can report the
latter as an error.  (Given that pcap supports more than just "regular
interfaces", though, there are cases where you don't have permission to
capture on those but you have permission to capture raw USB traffic, for
example, so perhaps what's really needed is per-interface indications of
permissions.)

Change-Id: I7b8abb0829e8502f5259c95e8af31655f79d36a1
Reviewed-on: https://code.wireshark.org/review/3169
Reviewed-by: Guy Harris <guy@alum.mit.edu>

12 files changed, 40 insertions, 73 deletions

diff --git a/capchild/capture_ifinfo.c b/capchild/capture_ifinfo.c
index 94af1c0274..54e4d4c4fc 100644
--- a/capchild/capture_ifinfo.c
+++ b/capchild/capture_ifinfo.c
@@ -116,6 +116,8 @@ capture_interface_list(int *err, char **err_str, void (*update_cb)(void))
 
     g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_MESSAGE, "Capture Interface List ...");
 
+    *err = 0;
+
     /* Try to get our interface list */
     ret = sync_interface_list_open(&data, &primary_msg, &secondary_msg, update_cb);
     if (ret != 0) {
@@ -188,9 +190,6 @@ capture_interface_list(int *err, char **err_str, void (*update_cb)(void))
     }
     g_strfreev(raw_list);
 
-    /* Check to see if we built a list */
-    if (if_list == NULL)
-        *err = NO_INTERFACES_FOUND;
 #ifdef HAVE_PCAP_REMOTE
     if (remote_interface_list && g_list_length(remote_interface_list) > 0) {
         append_remote_list(if_list);
diff --git a/capture_opts.c b/capture_opts.c
index 7b92f74760..313471f1b9 100644
--- a/capture_opts.c
+++ b/capture_opts.c
@@ -457,17 +457,11 @@ capture_opts_add_iface_opt(capture_options *capture_opts, const char *optarg_str
         }
         if_list = capture_interface_list(&err, &err_str, NULL);
         if (if_list == NULL) {
-            switch (err) {
-
-            case CANT_GET_INTERFACE_LIST:
-            case DONT_HAVE_PCAP:
+            if (err == 0)
+                cmdarg_err("There are no interfaces on which a capture can be done");
+            else {
                 cmdarg_err("%s", err_str);
                 g_free(err_str);
-                break;
-
-            case NO_INTERFACES_FOUND:
-                cmdarg_err("There are no interfaces on which a capture can be done");
-                break;
             }
             return 2;
         }
diff --git a/caputils/capture-pcap-util-unix.c b/caputils/capture-pcap-util-unix.c
index 21e832b166..66404500ce 100644
--- a/caputils/capture-pcap-util-unix.c
+++ b/caputils/capture-pcap-util-unix.c
@@ -308,7 +308,7 @@ get_interface_list(int *err, char **err_str)
 		/*
 		 * No interfaces found.
 		 */
-		*err = NO_INTERFACES_FOUND;
+		*err = 0;
 		if (err_str != NULL)
 			*err_str = NULL;
 	}
diff --git a/caputils/capture-pcap-util.c b/caputils/capture-pcap-util.c
index c4e7df3868..98054c4a0f 100644
--- a/caputils/capture-pcap-util.c
+++ b/caputils/capture-pcap-util.c
@@ -437,7 +437,7 @@ get_interface_list_findalldevs_ex(const char *source,
 		/*
 		 * No interfaces found.
 		 */
-		*err = NO_INTERFACES_FOUND;
+		*err = 0;
 		if (err_str != NULL)
 			*err_str = NULL;
 		return NULL;
@@ -474,7 +474,7 @@ get_interface_list_findalldevs(int *err, char **err_str)
 		/*
 		 * No interfaces found.
 		 */
-		*err = NO_INTERFACES_FOUND;
+		*err = 0;
 		if (err_str != NULL)
 			*err_str = NULL;
 		return NULL;
diff --git a/caputils/capture-wpcap.c b/caputils/capture-wpcap.c
index 707875d374..3fdff7d052 100644
--- a/caputils/capture-wpcap.c
+++ b/caputils/capture-wpcap.c
@@ -865,7 +865,7 @@ get_interface_list(int *err, char **err_str)
 		/*
 		 * No interfaces found.
 		 */
-		*err = NO_INTERFACES_FOUND;
+		*err = 0;
 		if (err_str != NULL)
 			*err_str = NULL;
 	}
diff --git a/caputils/capture_ifinfo.h b/caputils/capture_ifinfo.h
index 7cb70abbdf..2353f06fed 100644
--- a/caputils/capture_ifinfo.h
+++ b/caputils/capture_ifinfo.h
@@ -81,8 +81,7 @@ extern GList *capture_interface_list(int *err, char **err_str, void (*update_cb)
 
 /* Error values from "get_interface_list()/capture_interface_list()". */
 #define	CANT_GET_INTERFACE_LIST	1	/* error getting list */
-#define	NO_INTERFACES_FOUND	2	/* list is empty */
-#define	DONT_HAVE_PCAP		3	/* couldn't load WinPcap */
+#define	DONT_HAVE_PCAP		2	/* couldn't load WinPcap */
 
 void free_interface_list(GList *if_list);
 
diff --git a/dumpcap.c b/dumpcap.c
index 6975514523..29ec228198 100644
--- a/dumpcap.c
+++ b/dumpcap.c
@@ -1430,16 +1430,11 @@ print_statistics_loop(gboolean machine_readable)
 
     if_list = get_interface_list(&err, &err_str);
     if (if_list == NULL) {
-        switch (err) {
-        case CANT_GET_INTERFACE_LIST:
-        case DONT_HAVE_PCAP:
+    	if (err == 0)
+            cmdarg_err("There are no interfaces on which a capture can be done");
+        else {
             cmdarg_err("%s", err_str);
             g_free(err_str);
-            break;
-
-        case NO_INTERFACES_FOUND:
-            cmdarg_err("There are no interfaces on which a capture can be done");
-            break;
         }
         return err;
     }
@@ -4755,15 +4750,7 @@ main(int argc, char *argv[])
 
         if_list = capture_interface_list(&err, &err_str,NULL);
         if (if_list == NULL) {
-            switch (err) {
-            case CANT_GET_INTERFACE_LIST:
-            case DONT_HAVE_PCAP:
-                cmdarg_err("%s", err_str);
-                g_free(err_str);
-                exit_main(2);
-                break;
-
-            case NO_INTERFACES_FOUND:
+            if (err == 0) {
                 /*
                  * If we're being run by another program, just give them
                  * an empty list of interfaces, don't report this as
@@ -4774,7 +4761,10 @@ main(int argc, char *argv[])
                     cmdarg_err("There are no interfaces on which a capture can be done");
                     exit_main(2);
                 }
-                break;
+            } else {
+                cmdarg_err("%s", err_str);
+                g_free(err_str);
+                exit_main(2);
             }
         }
 
diff --git a/tshark.c b/tshark.c
index 5ac44b08e3..4980d77004 100644
--- a/tshark.c
+++ b/tshark.c
@@ -1377,16 +1377,11 @@ main(int argc, char *argv[])
 #ifdef HAVE_LIBPCAP
       if_list = capture_interface_list(&err, &err_str,NULL);
       if (if_list == NULL) {
-        switch (err) {
-        case CANT_GET_INTERFACE_LIST:
-        case DONT_HAVE_PCAP:
+      	if (err == 0)
+          cmdarg_err("There are no interfaces on which a capture can be done");
+        else {
           cmdarg_err("%s", err_str);
           g_free(err_str);
-          break;
-
-        case NO_INTERFACES_FOUND:
-          cmdarg_err("There are no interfaces on which a capture can be done");
-          break;
         }
         return 2;
       }
diff --git a/ui/gtk/main.c b/ui/gtk/main.c
index b747c5af17..17fa2a9a0d 100644
--- a/ui/gtk/main.c
+++ b/ui/gtk/main.c
@@ -2329,16 +2329,11 @@ main(int argc, char *argv[])
 #ifdef HAVE_LIBPCAP
                 if_list = capture_interface_list(&err, &err_str,main_window_update);
                 if (if_list == NULL) {
-                    switch (err) {
-                        case CANT_GET_INTERFACE_LIST:
-                        case DONT_HAVE_PCAP:
-                            cmdarg_err("%s", err_str);
-                            g_free(err_str);
-                            break;
-
-                        case NO_INTERFACES_FOUND:
-                            cmdarg_err("There are no interfaces on which a capture can be done");
-                            break;
+                    if (err == 0)
+                        cmdarg_err("There are no interfaces on which a capture can be done");
+                    else {
+                        cmdarg_err("%s", err_str);
+                        g_free(err_str);
                     }
                     exit(2);
                 }
diff --git a/ui/gtk/main_welcome.c b/ui/gtk/main_welcome.c
index 95c09dc0ab..1c1cb74c90 100644
--- a/ui/gtk/main_welcome.c
+++ b/ui/gtk/main_welcome.c
@@ -1076,6 +1076,13 @@ fill_capture_box(void)
        capture_interface_list(&error, &err_str,main_window_update);
        switch (error) {
 
+       case 0:
+            label_text = g_strdup("No interface can be used for capturing in "
+                                  "this system with the current configuration.\n"
+                                  "\n"
+                                  "See Capture Help below for details.");
+            break;
+
        case CANT_GET_INTERFACE_LIST:
             label_text = g_strdup_printf("No interface can be used for capturing in "
                                          "this system with the current configuration.\n\n"
@@ -1085,13 +1092,6 @@ fill_capture_box(void)
                                          err_str);
             break;
 
-       case NO_INTERFACES_FOUND:
-            label_text = g_strdup("No interface can be used for capturing in "
-                                  "this system with the current configuration.\n"
-                                  "\n"
-                                  "See Capture Help below for details.");
-            break;
-
        case DONT_HAVE_PCAP:
             label_text = g_strdup("WinPcap doesn't appear to be installed.  "
                                   "In order to capture packets, WinPcap "
@@ -1140,7 +1140,7 @@ fill_capture_box(void)
         g_signal_connect(w, "activate-link", G_CALLBACK(activate_link_cb), NULL);
 #endif
         g_object_set_data(G_OBJECT(welcome_hb), CAPTURE_LABEL, w);
-        if (error == CANT_GET_INTERFACE_LIST || error == NO_INTERFACES_FOUND) {
+        if (error == CANT_GET_INTERFACE_LIST || error == 0) {
           item_hb_refresh = welcome_button(GTK_STOCK_REFRESH,
                                            "Refresh Interfaces",
                                            "Get a new list of the local interfaces.",
diff --git a/ui/gtk/prefs_capture.c b/ui/gtk/prefs_capture.c
index 53bca5c809..a4227feb23 100644
--- a/ui/gtk/prefs_capture.c
+++ b/ui/gtk/prefs_capture.c
@@ -1775,7 +1775,7 @@ ifopts_if_liststore_add(void)
 
 	if_list = capture_interface_list(&err, &err_str, main_window_update);  /* if_list = ptr to first element of list (or NULL) */
 	if (if_list == NULL) {
-		if (err != NO_INTERFACES_FOUND) {
+		if (err != 0) {
 			simple_dialog(ESD_TYPE_ERROR, ESD_BTN_OK, "%s", err_str);
 		}
 		g_free(err_str);
diff --git a/ui/qt/main.cpp b/ui/qt/main.cpp
index eee5d65758..7ec385ddf1 100644
--- a/ui/qt/main.cpp
+++ b/ui/qt/main.cpp
@@ -673,16 +673,11 @@ int main(int argc, char *argv[])
 #ifdef HAVE_LIBPCAP
                 if_list = capture_interface_list(&err, &err_str,main_window_update);
                 if (if_list == NULL) {
-                    switch (err) {
-                        case CANT_GET_INTERFACE_LIST:
-                        case DONT_HAVE_PCAP:
-                            cmdarg_err("%s", err_str);
-                            g_free(err_str);
-                            break;
-
-                        case NO_INTERFACES_FOUND:
-                            cmdarg_err("There are no interfaces on which a capture can be done");
-                            break;
+                    if (err == 0)
+                        cmdarg_err("There are no interfaces on which a capture can be done");
+                    else {
+                        cmdarg_err("%s", err_str);
+                        g_free(err_str);
                     }
                     exit(2);
                 }