nfqws,tpws: always use line buffering for console IO

Forces stdout and stderr to always use line buffering. Note that glibc
does automatically flush on newline iff connected to a terminal, but
that is not the case when running under systemd. See also
https://www.gnu.org/software/libc/manual/html_node/Buffering-Concepts.html
https://www.gnu.org/software/libc/manual/html_node/Controlling-Buffering.html

nfq/helpers.c

@@ -391,6 +391,12 @@ void fill_random_az09(uint8_t *p,size_t sz)
 	}
 }
 
+void disable_console_io_buffering(void)
+{
+	setvbuf(stdout, NULL, _IOLBF, 0);
+	setvbuf(stderr, NULL, _IOLBF, 0);
+}
+
 bool set_env_exedir(const char *argv0)
 {
 	char *s,*d;

nfq/helpers.h

@@ -92,6 +92,7 @@ void fill_random_bytes(uint8_t *p,size_t sz);
 void fill_random_az(uint8_t *p,size_t sz);
 void fill_random_az09(uint8_t *p,size_t sz);
 
+void disable_console_io_buffering(void);
 bool set_env_exedir(const char *argv0);
 
 

nfq/nfqws.c

@@ -499,7 +499,6 @@ static int win_main(const char *windivert_filter)
 		if (!logical_net_filter_match())
 		{
 			DLOG_CONDUP("logical network is not present. waiting it to appear.\n");
-			fflush(stdout);
 			do
 			{
 				if (bQuit)
@@ -512,7 +511,6 @@ static int win_main(const char *windivert_filter)
 			}
 			while (!logical_net_filter_match());
 			DLOG_CONDUP("logical network now present\n");
-			fflush(stdout);
 		}
 
 		if (!windivert_init(windivert_filter))
@@ -523,10 +521,6 @@ static int win_main(const char *windivert_filter)
 
 		DLOG_CONDUP("windivert initialized. capture is started.\n");
 
-		// cygwin auto flush fails when piping
-		fflush(stdout);
-		fflush(stderr);
-
 		for (id=0;;id++)
 		{
 			len = sizeof(packet);
@@ -589,10 +583,6 @@ static int win_main(const char *windivert_filter)
 				default:
 					DLOG("packet: id=%u drop\n", id);
 			}
-	
-			// cygwin auto flush fails when piping
-			fflush(stdout);
-			fflush(stderr);
 		}
 	}
 	win_dark_deinit();
@@ -1424,6 +1414,7 @@ void check_dp(const struct desync_profile *dp)
 
 int main(int argc, char **argv)
 {
+	disable_console_io_buffering();
 	set_env_exedir(argv[0]);
 
 #ifdef __CYGWIN__

tpws/helpers.c

@@ -383,6 +383,11 @@ bool pf_is_empty(const port_filter *pf)
 	return !pf->neg && !pf->from && !pf->to;
 }
 
+void disable_console_io_buffering(void)
+{
+	setvbuf(stdout, NULL, _IOLBF, 0);
+	setvbuf(stderr, NULL, _IOLBF, 0);
+}
 
 bool set_env_exedir(const char *argv0)
 {

tpws/helpers.h

@@ -82,6 +82,7 @@ bool pf_in_range(uint16_t port, const port_filter *pf);
 bool pf_parse(const char *s, port_filter *pf);
 bool pf_is_empty(const port_filter *pf);
 
+void disable_console_io_buffering(void);
 bool set_env_exedir(const char *argv0);
 
 #ifndef IN_LOOPBACK

tpws/tpws.c

@@ -1707,6 +1707,7 @@ int main(int argc, char *argv[])
 	struct salisten_s list[MAX_BINDS];
 	char ip_port[48];
 
+	disable_console_io_buffering();
 	set_env_exedir(argv[0]);
 	srand(time(NULL));
 	mask_from_preflen6_prepare();

tpws/tpws_conn.c

@@ -1755,8 +1755,6 @@ int event_loop(const int *listen_fd, size_t listen_fd_ct)
 			// at least one leg was removed. recount legs
 			print_legs();
 		}
-
-		fflush(stderr); fflush(stdout); // for console messages
 	}
 
 ex: