Create/use passthru_socket_activate() function which will purge the

client_socket_dup before activating the passthru_socket. This resolves the
issue of external programs receiving stale data from the previous passthru
session - data that was not sucessfully read by the last external program
invoked.

src/sbbs3/main.cpp

@@ -2106,6 +2106,21 @@ void input_thread(void *arg)
 		,sbbs->cfg.node_num, total_recv, total_pkts);
 }
 
+// Flush the duplicate client_socket when activating the passthru socket
+// to eliminate any stale data from the previous passthru session
+void sbbs_t::passthru_socket_activate(bool activate)
+{
+	if(activate) {
+		BOOL rd = FALSE;
+		while(socket_check(client_socket_dup, &rd, /* wr_p */NULL, /* timeout */0) && rd) {
+			char ch;
+			if(recv(client_socket_dup, &ch, sizeof(ch), /* flags: */0) != sizeof(ch))
+				break;
+		}
+	}
+	passthru_socket_active = activate;
+}
+
 /*
  * This thread simply copies anything it manages to read from the
  * passthru_socket into the output ringbuffer.

src/sbbs3/sbbs.h

@@ -332,6 +332,7 @@ public:
 	bool	ssh_mode;
 	SOCKET	passthru_socket;
 	bool	passthru_socket_active;
+	void	passthru_socket_activate(bool);
     bool	passthru_thread_running;
 
 	scfg_t	cfg;

src/sbbs3/xtrn.cpp

@@ -678,7 +678,7 @@ int sbbs_t::external(const char* cmdline, long mode, const char* startup_dir)
 
 		if(!(mode&EX_STDIN)) {
 			if(passthru_thread_running)
-				passthru_socket_active = true;
+				passthru_socket_activate(true);
 			else
 				pthread_mutex_lock(&input_thread_mutex);
 		}
@@ -703,7 +703,7 @@ int sbbs_t::external(const char* cmdline, long mode, const char* startup_dir)
 		XTRN_CLEANUP;
 		if(!(mode&EX_STDIN)) {
 			if(passthru_thread_running)
-				passthru_socket_active = false;
+				passthru_socket_activate(false);
 			else
 				pthread_mutex_unlock(&input_thread_mutex);
 		}
@@ -1074,7 +1074,7 @@ int sbbs_t::external(const char* cmdline, long mode, const char* startup_dir)
 		if(native) {
 			if(!(mode&EX_STDIN)) {
 				if(passthru_thread_running)
-					passthru_socket_active = false;
+					passthru_socket_activate(false);
 				else
 					pthread_mutex_unlock(&input_thread_mutex);
 			}
@@ -1656,7 +1656,7 @@ int sbbs_t::external(const char* cmdline, long mode, const char* startup_dir)
 	if(!(mode&EX_STDIN)) {
 		if(!(mode&EX_STDIN)) {
 			if(passthru_thread_running)
-				passthru_socket_active = true;
+				passthru_socket_activate(true);
 			else
 				pthread_mutex_lock(&input_thread_mutex);
 		}
@@ -1687,7 +1687,7 @@ int sbbs_t::external(const char* cmdline, long mode, const char* startup_dir)
 		if((pid=forkpty(&in_pipe[1],NULL,&term,&winsize))==-1) {
 			if(!(mode&EX_STDIN)) {
 				if(passthru_thread_running)
-					passthru_socket_active = false;
+					passthru_socket_activate(false);
 				else
 					pthread_mutex_unlock(&input_thread_mutex);
 			}
@@ -1712,7 +1712,7 @@ int sbbs_t::external(const char* cmdline, long mode, const char* startup_dir)
 		if((pid=FORK())==-1) {
 			if(!(mode&EX_STDIN)) {
 				if(passthru_thread_running)
-					passthru_socket_active = false;
+					passthru_socket_activate(false);
 				else
 					pthread_mutex_unlock(&input_thread_mutex);
 			}
@@ -2011,7 +2011,7 @@ int sbbs_t::external(const char* cmdline, long mode, const char* startup_dir)
 
 	if(!(mode&EX_STDIN)) {
 		if(passthru_thread_running)
-			passthru_socket_active = false;
+			passthru_socket_activate(false);
 		else
 			pthread_mutex_unlock(&input_thread_mutex);
 	}