extcap: fix a bug in cfilter

When no filter is specified, interface_opts.cfilter is not null but an empty string.

Change-Id: I5755ab7dd840be28334768cf26999048441fcc4e
Reviewed-on: https://code.wireshark.org/review/11907
Reviewed-by: Stig Bjørlykke <stig@bjorlykke.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/extcap.c b/extcap.c
index 1e89a5ce41..c161e48c39 100644
--- a/extcap.c
+++ b/extcap.c
@@ -583,7 +583,7 @@ extcaps_init_initerfaces(capture_options *capture_opts)
         add_arg(EXTCAP_ARGUMENT_RUN_CAPTURE);
         add_arg(EXTCAP_ARGUMENT_INTERFACE);
         add_arg(interface_opts.name);
-        if (interface_opts.cfilter) {
+        if (strlen(interface_opts.cfilter) > 0) {
             add_arg(EXTCAP_ARGUMENT_CAPTURE_FILTER);
             add_arg(interface_opts.cfilter);
         }