改进：TP核心服务每60秒向已连接的客户端和远程主机发送keep-alive消息，防止连接中断。但仍保留无操作超时就断开的限制。

server/tp_core/protocol/ssh/ssh_proxy.cpp

@@ -6,7 +6,8 @@ SshProxy g_ssh_proxy;
 SshProxy::SshProxy() :
         ExThreadBase("ssh-proxy-thread"),
         m_bind(NULL) {
-    m_timer_counter = 0;
+    m_timer_counter_check_noop = 0;
+    m_timer_counter_send_keep_alive= 0;
     m_noop_timeout_sec = 900; // default to 15 minutes.
     m_listener_running = false;
 }
@@ -59,15 +60,16 @@ bool SshProxy::init() {
 }
 
 void SshProxy::timer() {
-    // timer() will be called per one second, and I will do my job per 5 seconds.
-    m_timer_counter++;
-    if (m_timer_counter < 5)
-        return;
+    // timer() will be called per one second
+    m_timer_counter_check_noop++;
+    m_timer_counter_send_keep_alive++;
 
-    m_timer_counter = 0;
+    // check no-op per 5 seconds.
+    if (m_timer_counter_check_noop >= 5) {
+        m_timer_counter_check_noop = 0;
 
         ExThreadSmartLock locker(m_lock);
-    ex_u32 t_now = (ex_u32) time(NULL);
+        ex_u32 t_now = (ex_u32)time(NULL);
 
         ts_ssh_sessions::iterator it;
         for (it = m_sessions.begin(); it != m_sessions.end(); ++it) {
@@ -75,6 +77,17 @@ void SshProxy::timer() {
             if (0 != m_noop_timeout_sec)
                 it->first->check_noop_timeout(t_now, m_noop_timeout_sec);
         }
+    }
+
+    // send keep-alive every 60 seconds
+    if (m_timer_counter_send_keep_alive >= 60) {
+        m_timer_counter_send_keep_alive = 0;
+        ExThreadSmartLock locker(m_lock);
+        ts_ssh_sessions::iterator it;
+        for (it = m_sessions.begin(); it != m_sessions.end(); ++it) {
+            it->first->send_keep_alive();
+        }
+    }
 }
 
 void SshProxy::set_cfg(ex_u32 noop_timeout) {

server/tp_core/protocol/ssh/ssh_proxy.h

@@ -26,7 +26,8 @@ protected:
 
 private:
 	ssh_bind m_bind;
-	int m_timer_counter;
+    int m_timer_counter_check_noop;
+    int m_timer_counter_send_keep_alive;
 
 	ExThreadLock m_lock;
     bool m_listener_running;

server/tp_core/protocol/ssh/ssh_session.cpp

@@ -399,7 +399,7 @@ void SshSession::save_record() {
 }
 
 void SshSession::check_noop_timeout(ex_u32 t_now, ex_u32 timeout) {
-    ExThreadSmartLock locker(m_lock);
+    // ExThreadSmartLock locker(m_lock);
     tp_channels::iterator it = m_channels.begin();
     for (; it != m_channels.end(); ++it) {
         if ((*it)->need_close)
@@ -415,6 +415,15 @@ void SshSession::check_noop_timeout(ex_u32 t_now, ex_u32 timeout) {
     }
 }
 
+void SshSession::send_keep_alive() {
+    EXLOGD("[ssh] send keep-alive.\n");
+    if(m_srv_session)
+        ssh_send_keepalive(m_srv_session);
+    if (m_cli_session)
+        ssh_send_keepalive(m_cli_session);
+}
+
+
 int SshSession::_on_auth_password_request(ssh_session session, const char *user, const char *password, void *userdata) {
     // here, `user` is the session-id we need.
     SshSession *_this = (SshSession *) userdata;

server/tp_core/protocol/ssh/ssh_session.h

@@ -1,4 +1,4 @@
-#ifndef __SSH_SESSION_H__
+#ifndef __SSH_SESSION_H__
 #define __SSH_SESSION_H__
 
 #include "ssh_recorder.h"
@@ -78,6 +78,7 @@ public:
 	void save_record();
 	// 
 	void check_noop_timeout(ex_u32 t_now, ex_u32 timeout);
+    void send_keep_alive();
 
 	const ex_astr& sid() { return m_sid; }
 
@@ -140,13 +141,13 @@ private:
 
 	int m_ssh_ver;
 
-	// 一个ssh_session中可以打开多个ssh_channel
+	// 一个ssh_session中可以打开多个ssh_channel
 	tp_channels m_channels;
 
 	bool m_have_error;
 
-	bool m_recving_from_srv;		// 是否正在从服务器接收数据？
-	bool m_recving_from_cli;		// 是否正在从客户端接收数据？
+	bool m_recving_from_srv;		// 是否正在从服务器接收数据？
+	bool m_recving_from_cli;		// 是否正在从客户端接收数据？
 
 	struct ssh_server_callbacks_struct m_srv_cb;
 	struct ssh_channel_callbacks_struct m_cli_channel_cb;