extcap: Do not hang if extcap doesn't open fifo

Simply open and close the fifo as part of cleanup. Doing so lets dumpcap
know that the capture has finished if extcap did not open the pipe. This
is only needed on *NIX systems, because there was no hang on Windows.

Fixes #18715

1 files changed, 9 insertions, 0 deletions

diff --git a/extcap.c b/extcap.c
index b553127c58..ee7e469f45 100644
--- a/extcap.c
+++ b/extcap.c
@@ -1343,6 +1343,15 @@ gboolean extcap_session_stop(capture_session *cap_session)
 #else
         if (interface_opts->extcap_fifo != NULL && file_exists(interface_opts->extcap_fifo))
         {
+            /* If extcap didn't open the fifo, dumpcap would be waiting on it
+             * until user manually stops capture. Simply open and close fifo
+             * here to let dumpcap return from the select() call. This has no
+             * effect if dumpcap is not waiting.
+             */
+            int fd = ws_open(interface_opts->extcap_fifo, O_WRONLY, 0000);
+            if (fd != -1) {
+                close(fd);
+            }
             /* the fifo will not be freed here, but with the other capture_opts in capture_sync */
             ws_unlink(interface_opts->extcap_fifo);
             interface_opts->extcap_fifo = NULL;