From f42f05aab70b28a9cfd407e26978ebb5263d8787 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Tue, 30 May 2017 16:40:33 -0400
Subject: [PATCH 01/20] GUACAMOLE-203: Add option entries for
 ServerAliveInterval.

---
 src/protocols/ssh/settings.c | 12 ++++++++++++
 src/protocols/ssh/settings.h |  5 +++++
 2 files changed, 17 insertions(+)

diff --git a/src/protocols/ssh/settings.c b/src/protocols/ssh/settings.c
index 35f88e0f..91ec9e66 100644
--- a/src/protocols/ssh/settings.c
+++ b/src/protocols/ssh/settings.c
@@ -51,6 +51,7 @@ const char* GUAC_SSH_CLIENT_ARGS[] = {
     "recording-name",
     "create-recording-path",
     "read-only",
+    "server-alive-interval",
     NULL
 };
 
@@ -165,6 +166,12 @@ enum SSH_ARGS_IDX {
      */
     IDX_READ_ONLY,
 
+    /**
+     * Number of seconds between sending alive packets.  A default of 0
+     * tells SSH not to send these packets.
+     */
+    IDX_SERVER_ALIVE_INTERVAL,
+
     SSH_ARGS_COUNT
 };
 
@@ -279,6 +286,11 @@ guac_ssh_settings* guac_ssh_parse_args(guac_user* user,
         guac_user_parse_args_boolean(user, GUAC_SSH_CLIENT_ARGS, argv,
                 IDX_CREATE_RECORDING_PATH, false);
 
+    /* Parse server alive interval */
+    settings->server_alive_interval =
+        guac_user_parse_args_int(user, GUAC_SSH_CLIENT_ARGS, argv,
+                IDX_SERVER_ALIVE_INTERVAL, 0);
+
     /* Parsing was successful */
     return settings;
 
diff --git a/src/protocols/ssh/settings.h b/src/protocols/ssh/settings.h
index 6d3e47a5..3440e5b2 100644
--- a/src/protocols/ssh/settings.h
+++ b/src/protocols/ssh/settings.h
@@ -181,6 +181,11 @@ typedef struct guac_ssh_settings {
      */
     bool create_recording_path;
 
+    /**
+     * The number of seconds between sending server alive messages.
+     */
+    int server_alive_interval;
+
 } guac_ssh_settings;
 
 /**

From 8ab7e56972f4b7049a886cc6eb425ed2a3bdc277 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Wed, 31 May 2017 08:00:09 -0400
Subject: [PATCH 02/20] GUACAMOLE-203: Implement keepalive config in SSH
 connection.

---
 src/protocols/ssh/ssh.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index 43e66f8b..fc5e4083 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -224,6 +224,11 @@ void* ssh_client_thread(void* data) {
         return NULL;
     }
 
+    /* Set keepalive configuration for session */
+    if (settings->server_alive_interval > 0) {
+        libssh2_keepalive_config(ssh_client->session->session, 1, settings->server_alive_interval);
+    }
+
     pthread_mutex_init(&ssh_client->term_channel_lock, NULL);
 
     /* Open channel for terminal */
@@ -318,11 +323,18 @@ void* ssh_client_thread(void* data) {
 
     /* While data available, write to terminal */
     int bytes_read = 0;
+    int timeout = 0;
     for (;;) {
 
         /* Track total amount of data read */
         int total_read = 0;
 
+        /* Set up return value for keepalives */
+        int alive = 0;
+
+        /* Timer for keepalives */
+        int sleep = 0;
+
         pthread_mutex_lock(&(ssh_client->term_channel_lock));
 
         /* Stop reading at EOF */
@@ -331,6 +343,16 @@ void* ssh_client_thread(void* data) {
             break;
         }
 
+        /* Send keepalive at configured interval */
+        if (settings->server_alive_interval > 0) {
+            alive = libssh2_keepalive_send(ssh_client->session->session, &timeout);
+            if (alive > 0)
+                break;
+            sleep = timeout * 1000;
+        }
+        else
+            sleep = 1000;
+
         /* Read terminal data */
         bytes_read = libssh2_channel_read(ssh_client->term_channel,
                 buffer, sizeof(buffer));
@@ -370,8 +392,8 @@ void* ssh_client_thread(void* data) {
                 .revents = 0,
             }};
 
-            /* Wait up to one second */
-            if (poll(fds, 1, 1000) < 0)
+            /* Wait up to computed sleep time */
+            if (poll(fds, 1, sleep) < 0)
                 break;
 
         }

From 75019f5e4bd01d5889b496d847b2dd2c64d0244f Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Wed, 31 May 2017 08:30:56 -0400
Subject: [PATCH 03/20] GUACAMOLE-203: Add a few more comments to code.

---
 src/protocols/ssh/ssh.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index fc5e4083..36055c80 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -346,10 +346,12 @@ void* ssh_client_thread(void* data) {
         /* Send keepalive at configured interval */
         if (settings->server_alive_interval > 0) {
             alive = libssh2_keepalive_send(ssh_client->session->session, &timeout);
+            /* Sending the keepalive failed, so we break out */
             if (alive > 0)
                 break;
             sleep = timeout * 1000;
         }
+        /* If keepalive is not configured, sleep for the default of 1 second */
         else
             sleep = 1000;
 

From f693b02e126e7d3f348744fdf0975278c897add2 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Wed, 31 May 2017 19:33:47 -0400
Subject: [PATCH 04/20] GUACAMOLE-203: Tighten up code, implement constant for
 socket poll timer.

---
 src/protocols/ssh/settings.h |  5 +++++
 src/protocols/ssh/ssh.c      | 26 ++++++++++----------------
 2 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/src/protocols/ssh/settings.h b/src/protocols/ssh/settings.h
index 3440e5b2..e831d9e9 100644
--- a/src/protocols/ssh/settings.h
+++ b/src/protocols/ssh/settings.h
@@ -53,6 +53,11 @@
  */
 #define GUAC_SSH_DEFAULT_RECORDING_NAME "recording"
 
+/**
+ * The default polling timer for SSH activity in milliseconds.
+ */
+#define GUAC_SSH_DEFAULT_POLL_TIMER 1000
+
 /**
  * Settings for the SSH connection. The values for this structure are parsed
  * from the arguments given during the Guacamole protocol handshake using the
diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index 36055c80..a1b3d93c 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -225,9 +225,8 @@ void* ssh_client_thread(void* data) {
     }
 
     /* Set keepalive configuration for session */
-    if (settings->server_alive_interval > 0) {
+    if (settings->server_alive_interval > 1)
         libssh2_keepalive_config(ssh_client->session->session, 1, settings->server_alive_interval);
-    }
 
     pthread_mutex_init(&ssh_client->term_channel_lock, NULL);
 
@@ -323,17 +322,13 @@ void* ssh_client_thread(void* data) {
 
     /* While data available, write to terminal */
     int bytes_read = 0;
-    int timeout = 0;
     for (;;) {
 
         /* Track total amount of data read */
         int total_read = 0;
 
-        /* Set up return value for keepalives */
-        int alive = 0;
-
-        /* Timer for keepalives */
-        int sleep = 0;
+        /* Timer for polling socket activity */
+        int timer;
 
         pthread_mutex_lock(&(ssh_client->term_channel_lock));
 
@@ -344,16 +339,15 @@ void* ssh_client_thread(void* data) {
         }
 
         /* Send keepalive at configured interval */
-        if (settings->server_alive_interval > 0) {
-            alive = libssh2_keepalive_send(ssh_client->session->session, &timeout);
-            /* Sending the keepalive failed, so we break out */
-            if (alive > 0)
+        if (settings->server_alive_interval > 1) {
+            int timeout = 0;
+            if(libssh2_keepalive_send(ssh_client->session->session, &timeout) > 0)
                 break;
-            sleep = timeout * 1000;
+            timer = timeout * 1000;
         }
         /* If keepalive is not configured, sleep for the default of 1 second */
         else
-            sleep = 1000;
+            timer = GUAC_SSH_DEFAULT_POLL_TIMER;
 
         /* Read terminal data */
         bytes_read = libssh2_channel_read(ssh_client->term_channel,
@@ -394,8 +388,8 @@ void* ssh_client_thread(void* data) {
                 .revents = 0,
             }};
 
-            /* Wait up to computed sleep time */
-            if (poll(fds, 1, sleep) < 0)
+            /* Wait up to computed timer */
+            if (poll(fds, 1, timer) < 0)
                 break;
 
         }

From 1e3d82cc63c6764cdd19d7c51978188021d9391b Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Wed, 31 May 2017 19:36:20 -0400
Subject: [PATCH 05/20] GUACAMOLE-203: Update comment for keep alive interval.

---
 src/protocols/ssh/settings.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/protocols/ssh/settings.c b/src/protocols/ssh/settings.c
index 91ec9e66..8843923b 100644
--- a/src/protocols/ssh/settings.c
+++ b/src/protocols/ssh/settings.c
@@ -168,7 +168,8 @@ enum SSH_ARGS_IDX {
 
     /**
      * Number of seconds between sending alive packets.  A default of 0
-     * tells SSH not to send these packets.
+     * tells SSH not to send these packets.  A value of 1 is automatically
+     * changed by libssh2 to 2 to avoid busy-loop corner cases.
      */
     IDX_SERVER_ALIVE_INTERVAL,
 

From 999368420583263207d669165946e217c556af76 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Wed, 31 May 2017 19:47:09 -0400
Subject: [PATCH 06/20] GUACAMOLE-203: Warn user if they try to enter keepalive
 value < 2 seconds.

---
 src/protocols/ssh/settings.c | 3 +++
 src/protocols/ssh/ssh.c      | 4 ++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/protocols/ssh/settings.c b/src/protocols/ssh/settings.c
index 8843923b..98594153 100644
--- a/src/protocols/ssh/settings.c
+++ b/src/protocols/ssh/settings.c
@@ -291,6 +291,9 @@ guac_ssh_settings* guac_ssh_parse_args(guac_user* user,
     settings->server_alive_interval =
         guac_user_parse_args_int(user, GUAC_SSH_CLIENT_ARGS, argv,
                 IDX_SERVER_ALIVE_INTERVAL, 0);
+    if (settings->server_alive_interval == 1)
+        guac_user_log(user, GUAC_LOG_WARNING, "Minimum keepalive interval "
+                " for libssh2 is 2 seconds.");
 
     /* Parsing was successful */
     return settings;
diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index a1b3d93c..2504df92 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -225,7 +225,7 @@ void* ssh_client_thread(void* data) {
     }
 
     /* Set keepalive configuration for session */
-    if (settings->server_alive_interval > 1)
+    if (settings->server_alive_interval > 0)
         libssh2_keepalive_config(ssh_client->session->session, 1, settings->server_alive_interval);
 
     pthread_mutex_init(&ssh_client->term_channel_lock, NULL);
@@ -339,7 +339,7 @@ void* ssh_client_thread(void* data) {
         }
 
         /* Send keepalive at configured interval */
-        if (settings->server_alive_interval > 1) {
+        if (settings->server_alive_interval > 0) {
             int timeout = 0;
             if(libssh2_keepalive_send(ssh_client->session->session, &timeout) > 0)
                 break;

From e7fc8a0d98aeef29ee7e2d5ff9b7520bdf42dc32 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Wed, 31 May 2017 20:17:00 -0400
Subject: [PATCH 07/20] GUACAMOLE-203: Expand SSH keepalives to cover SFTP
 connections for other protocols.

---
 src/common-ssh/common-ssh/ssh.h | 2 +-
 src/common-ssh/ssh.c            | 6 +++++-
 src/protocols/rdp/rdp.c         | 2 +-
 src/protocols/rdp/rdp.h         | 5 +++++
 src/protocols/ssh/ssh.c         | 8 ++------
 src/protocols/vnc/vnc.c         | 2 +-
 src/protocols/vnc/vnc.h         | 5 +++++
 7 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/src/common-ssh/common-ssh/ssh.h b/src/common-ssh/common-ssh/ssh.h
index d96ce44c..ff8621e9 100644
--- a/src/common-ssh/common-ssh/ssh.h
+++ b/src/common-ssh/common-ssh/ssh.h
@@ -98,7 +98,7 @@ void guac_common_ssh_uninit();
  *     if the connection or authentication were not successful.
  */
 guac_common_ssh_session* guac_common_ssh_create_session(guac_client* client,
-        const char* hostname, const char* port, guac_common_ssh_user* user);
+        const char* hostname, const char* port, guac_common_ssh_user* user, const int keepalive);
 
 /**
  * Disconnects and destroys the given SSH session, freeing all associated
diff --git a/src/common-ssh/ssh.c b/src/common-ssh/ssh.c
index 57bc8217..3bff4b39 100644
--- a/src/common-ssh/ssh.c
+++ b/src/common-ssh/ssh.c
@@ -414,7 +414,7 @@ static int guac_common_ssh_authenticate(guac_common_ssh_session* common_session)
 }
 
 guac_common_ssh_session* guac_common_ssh_create_session(guac_client* client,
-        const char* hostname, const char* port, guac_common_ssh_user* user) {
+        const char* hostname, const char* port, guac_common_ssh_user* user, const int keepalive) {
 
     int retval;
 
@@ -532,6 +532,10 @@ guac_common_ssh_session* guac_common_ssh_create_session(guac_client* client,
         return NULL;
     }
 
+    /* Configure session keepalive */
+    if (keepalive > 0)
+        libssh2_keepalive_config(common_session->session, 1, keepalive);
+
     /* Return created session */
     return common_session;
 
diff --git a/src/protocols/rdp/rdp.c b/src/protocols/rdp/rdp.c
index cf9be2ef..bbe76851 100644
--- a/src/protocols/rdp/rdp.c
+++ b/src/protocols/rdp/rdp.c
@@ -977,7 +977,7 @@ void* guac_rdp_client_thread(void* data) {
         /* Attempt SSH connection */
         rdp_client->sftp_session =
             guac_common_ssh_create_session(client, settings->sftp_hostname,
-                    settings->sftp_port, rdp_client->sftp_user);
+                    settings->sftp_port, rdp_client->sftp_user, rdp_client->sftp_keepalive);
 
         /* Fail if SSH connection does not succeed */
         if (rdp_client->sftp_session == NULL) {
diff --git a/src/protocols/rdp/rdp.h b/src/protocols/rdp/rdp.h
index 943155dd..70e909b1 100644
--- a/src/protocols/rdp/rdp.h
+++ b/src/protocols/rdp/rdp.h
@@ -141,6 +141,11 @@ typedef struct guac_rdp_client {
      * An SFTP-based filesystem.
      */
     guac_common_ssh_sftp_filesystem* sftp_filesystem;
+
+    /**
+     * A keepalive interval for SFTP connections.
+     */
+    int sftp_keepalive;
 #endif
 
     /**
diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index 2504df92..86c1fdfc 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -218,16 +218,12 @@ void* ssh_client_thread(void* data) {
 
     /* Open SSH session */
     ssh_client->session = guac_common_ssh_create_session(client,
-            settings->hostname, settings->port, ssh_client->user);
+            settings->hostname, settings->port, ssh_client->user, settings->server_alive_interval);
     if (ssh_client->session == NULL) {
         /* Already aborted within guac_common_ssh_create_session() */
         return NULL;
     }
 
-    /* Set keepalive configuration for session */
-    if (settings->server_alive_interval > 0)
-        libssh2_keepalive_config(ssh_client->session->session, 1, settings->server_alive_interval);
-
     pthread_mutex_init(&ssh_client->term_channel_lock, NULL);
 
     /* Open channel for terminal */
@@ -262,7 +258,7 @@ void* ssh_client_thread(void* data) {
         guac_client_log(client, GUAC_LOG_DEBUG, "Reconnecting for SFTP...");
         ssh_client->sftp_session =
             guac_common_ssh_create_session(client, settings->hostname,
-                    settings->port, ssh_client->user);
+                    settings->port, ssh_client->user, settings->server_alive_interval);
         if (ssh_client->sftp_session == NULL) {
             /* Already aborted within guac_common_ssh_create_session() */
             return NULL;
diff --git a/src/protocols/vnc/vnc.c b/src/protocols/vnc/vnc.c
index 8678ee29..4410e5f7 100644
--- a/src/protocols/vnc/vnc.c
+++ b/src/protocols/vnc/vnc.c
@@ -261,7 +261,7 @@ void* guac_vnc_client_thread(void* data) {
         /* Attempt SSH connection */
         vnc_client->sftp_session =
             guac_common_ssh_create_session(client, settings->sftp_hostname,
-                    settings->sftp_port, vnc_client->sftp_user);
+                    settings->sftp_port, vnc_client->sftp_user, vnc_client->sftp_keepalive);
 
         /* Fail if SSH connection does not succeed */
         if (vnc_client->sftp_session == NULL) {
diff --git a/src/protocols/vnc/vnc.h b/src/protocols/vnc/vnc.h
index 0edbcd47..a09f3ed3 100644
--- a/src/protocols/vnc/vnc.h
+++ b/src/protocols/vnc/vnc.h
@@ -108,6 +108,11 @@ typedef struct guac_vnc_client {
      * An SFTP-based filesystem.
      */
     guac_common_ssh_sftp_filesystem* sftp_filesystem;
+
+    /**
+     * The interval at which to send SSH keepalive messages for SFTP.
+     */
+    int sftp_keepalive;
 #endif
 
     /**

From 03403e3ea5cb132901c68cbc39b2ed6ac02a9fbc Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Wed, 31 May 2017 20:52:07 -0400
Subject: [PATCH 08/20] GUACAMOLE-203: Correct implementation of SSH keepalive
 option for SFTP connections across all protocols.

---
 src/protocols/rdp/rdp.c          |  2 +-
 src/protocols/rdp/rdp.h          |  5 -----
 src/protocols/rdp/rdp_settings.c | 16 ++++++++++++++++
 src/protocols/rdp/rdp_settings.h |  8 ++++++++
 src/protocols/vnc/settings.c     | 17 +++++++++++++++++
 src/protocols/vnc/settings.h     |  8 ++++++++
 src/protocols/vnc/vnc.c          |  2 +-
 src/protocols/vnc/vnc.h          |  5 -----
 8 files changed, 51 insertions(+), 12 deletions(-)

diff --git a/src/protocols/rdp/rdp.c b/src/protocols/rdp/rdp.c
index bbe76851..7b52a917 100644
--- a/src/protocols/rdp/rdp.c
+++ b/src/protocols/rdp/rdp.c
@@ -977,7 +977,7 @@ void* guac_rdp_client_thread(void* data) {
         /* Attempt SSH connection */
         rdp_client->sftp_session =
             guac_common_ssh_create_session(client, settings->sftp_hostname,
-                    settings->sftp_port, rdp_client->sftp_user, rdp_client->sftp_keepalive);
+                    settings->sftp_port, rdp_client->sftp_user, settings->sftp_keepalive);
 
         /* Fail if SSH connection does not succeed */
         if (rdp_client->sftp_session == NULL) {
diff --git a/src/protocols/rdp/rdp.h b/src/protocols/rdp/rdp.h
index 70e909b1..943155dd 100644
--- a/src/protocols/rdp/rdp.h
+++ b/src/protocols/rdp/rdp.h
@@ -141,11 +141,6 @@ typedef struct guac_rdp_client {
      * An SFTP-based filesystem.
      */
     guac_common_ssh_sftp_filesystem* sftp_filesystem;
-
-    /**
-     * A keepalive interval for SFTP connections.
-     */
-    int sftp_keepalive;
 #endif
 
     /**
diff --git a/src/protocols/rdp/rdp_settings.c b/src/protocols/rdp/rdp_settings.c
index 998f0a21..32c09415 100644
--- a/src/protocols/rdp/rdp_settings.c
+++ b/src/protocols/rdp/rdp_settings.c
@@ -84,6 +84,7 @@ const char* GUAC_RDP_CLIENT_ARGS[] = {
     "sftp-private-key",
     "sftp-passphrase",
     "sftp-directory",
+    "sftp-keepalive",
 #endif
 
     "recording-path",
@@ -366,6 +367,13 @@ enum RDP_ARGS_IDX {
      */
     IDX_SFTP_DIRECTORY,
 
+    /**
+     * The interval at which SSH keepalive messages are sent to the server for
+     * SFTP connections.  The default is 0 (disabling keepalives), and a value
+     * of 1 is automatically increased to 2 by libssh2 to avoid busy loop corner
+     * cases.
+     */
+    IDX_SFTP_KEEPALIVE,
 #endif
 
     /**
@@ -775,6 +783,14 @@ guac_rdp_settings* guac_rdp_parse_args(guac_user* user,
     settings->sftp_directory =
         guac_user_parse_args_string(user, GUAC_RDP_CLIENT_ARGS, argv,
                 IDX_SFTP_DIRECTORY, NULL);
+
+    /* Default keepalive value */
+    settings->sftp_keepalive =
+        guac_user_parse_args_int(user, GUAC_RDP_CLIENT_ARGS, argv,
+                IDX_SFTP_KEEPALIVE, 0);
+    if (settings->sftp_keepalive == 1)
+        guac_user_log(user, GUAC_LOG_WARNING, "The minimum allowed "
+                "value for keepalives by libssh2 is 2 seconds.");
 #endif
 
     /* Read recording path */
diff --git a/src/protocols/rdp/rdp_settings.h b/src/protocols/rdp/rdp_settings.h
index 3ff634ad..47e5289a 100644
--- a/src/protocols/rdp/rdp_settings.h
+++ b/src/protocols/rdp/rdp_settings.h
@@ -359,6 +359,14 @@ typedef struct guac_rdp_settings {
      * the destination directory is otherwise ambiguous).
      */
     char* sftp_directory;
+
+    /**
+     * The interval at which SSH keepalive messages are sent to the server for
+     * SFTP connections.  The default is 0 (disabling keepalives), and a value
+     * of 1 is automatically increased to 2 by libssh2 to avoid busy loop corner
+     * cases.
+     */
+    int sftp_keepalive;
 #endif
 
     /**
diff --git a/src/protocols/vnc/settings.c b/src/protocols/vnc/settings.c
index 0977af19..60e2f61c 100644
--- a/src/protocols/vnc/settings.c
+++ b/src/protocols/vnc/settings.c
@@ -66,6 +66,7 @@ const char* GUAC_VNC_CLIENT_ARGS[] = {
     "sftp-private-key",
     "sftp-passphrase",
     "sftp-directory",
+    "sftp-keepalive",
 #endif
 
     "recording-path",
@@ -227,6 +228,14 @@ enum VNC_ARGS_IDX {
      * the destination directory is otherwise ambiguous).
      */
     IDX_SFTP_DIRECTORY,
+
+    /**
+     * The interval at which SSH keepalive messages are sent to the server for
+     * SFTP connections.  The default is 0 (disabling keepalives), and a value
+     * of 1 is automatically increased to 2 by libssh2 to avoid busy loop corner
+     * cases.
+     */
+    IDX_SFTP_KEEPALIVE,
 #endif
 
     /**
@@ -395,6 +404,14 @@ guac_vnc_settings* guac_vnc_parse_args(guac_user* user,
     settings->sftp_directory =
         guac_user_parse_args_string(user, GUAC_VNC_CLIENT_ARGS, argv,
                 IDX_SFTP_DIRECTORY, NULL);
+
+    /* Default keepalive value */
+    settings->sftp_keepalive =
+        guac_user_parse_args_int(user, GUAC_VNC_CLIENT_ARGS, argv,
+                IDX_SFTP_KEEPALIVE, 0);
+    if (settings->sftp_keepalive == 1)
+        guac_user_log(user, GUAC_LOG_WARNING, "The minimum allowed "
+                "value for keepalives by libssh2 is 2 seconds.");
 #endif
 
     /* Read recording path */
diff --git a/src/protocols/vnc/settings.h b/src/protocols/vnc/settings.h
index 17626676..ba1bfdde 100644
--- a/src/protocols/vnc/settings.h
+++ b/src/protocols/vnc/settings.h
@@ -173,6 +173,14 @@ typedef struct guac_vnc_settings {
      * the destination directory is otherwise ambiguous).
      */
     char* sftp_directory;
+
+    /**
+     * The interval at which SSH keepalive messages are sent to the server for
+     * SFTP connections.  The default is 0 (disabling keepalives), and a value
+     * of 1 is automatically increased to 2 by libssh2 to avoid busy loop corner
+     * cases.
+     */
+    int sftp_keepalive;
 #endif
 
     /**
diff --git a/src/protocols/vnc/vnc.c b/src/protocols/vnc/vnc.c
index 4410e5f7..9aac436b 100644
--- a/src/protocols/vnc/vnc.c
+++ b/src/protocols/vnc/vnc.c
@@ -261,7 +261,7 @@ void* guac_vnc_client_thread(void* data) {
         /* Attempt SSH connection */
         vnc_client->sftp_session =
             guac_common_ssh_create_session(client, settings->sftp_hostname,
-                    settings->sftp_port, vnc_client->sftp_user, vnc_client->sftp_keepalive);
+                    settings->sftp_port, vnc_client->sftp_user, settings->sftp_keepalive);
 
         /* Fail if SSH connection does not succeed */
         if (vnc_client->sftp_session == NULL) {
diff --git a/src/protocols/vnc/vnc.h b/src/protocols/vnc/vnc.h
index a09f3ed3..0edbcd47 100644
--- a/src/protocols/vnc/vnc.h
+++ b/src/protocols/vnc/vnc.h
@@ -108,11 +108,6 @@ typedef struct guac_vnc_client {
      * An SFTP-based filesystem.
      */
     guac_common_ssh_sftp_filesystem* sftp_filesystem;
-
-    /**
-     * The interval at which to send SSH keepalive messages for SFTP.
-     */
-    int sftp_keepalive;
 #endif
 
     /**

From 070bd2572170f84c95d1c2801959a85e640dbfbe Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Wed, 14 Jun 2017 08:27:09 -0400
Subject: [PATCH 09/20] GUACAMOLE-203: if statement style tweak

---
 src/protocols/ssh/ssh.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index 86c1fdfc..59039bb6 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -337,7 +337,7 @@ void* ssh_client_thread(void* data) {
         /* Send keepalive at configured interval */
         if (settings->server_alive_interval > 0) {
             int timeout = 0;
-            if(libssh2_keepalive_send(ssh_client->session->session, &timeout) > 0)
+            if (libssh2_keepalive_send(ssh_client->session->session, &timeout) > 0)
                 break;
             timer = timeout * 1000;
         }

From 193051dfd534f18ef6d87b0359d2802daee6d195 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Wed, 14 Jun 2017 08:40:07 -0400
Subject: [PATCH 10/20] GUACAMOLE-203: Change parameter name for consistency

---
 src/protocols/rdp/rdp_settings.c | 6 +++---
 src/protocols/vnc/settings.c     | 8 ++++----
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/protocols/rdp/rdp_settings.c b/src/protocols/rdp/rdp_settings.c
index 32c09415..2b6635f8 100644
--- a/src/protocols/rdp/rdp_settings.c
+++ b/src/protocols/rdp/rdp_settings.c
@@ -84,7 +84,7 @@ const char* GUAC_RDP_CLIENT_ARGS[] = {
     "sftp-private-key",
     "sftp-passphrase",
     "sftp-directory",
-    "sftp-keepalive",
+    "sftp-server-alive-interval",
 #endif
 
     "recording-path",
@@ -373,7 +373,7 @@ enum RDP_ARGS_IDX {
      * of 1 is automatically increased to 2 by libssh2 to avoid busy loop corner
      * cases.
      */
-    IDX_SFTP_KEEPALIVE,
+    IDX_SFTP_SERVER_ALIVE_INTERVAL,
 #endif
 
     /**
@@ -787,7 +787,7 @@ guac_rdp_settings* guac_rdp_parse_args(guac_user* user,
     /* Default keepalive value */
     settings->sftp_keepalive =
         guac_user_parse_args_int(user, GUAC_RDP_CLIENT_ARGS, argv,
-                IDX_SFTP_KEEPALIVE, 0);
+                IDX_SFTP_SERVER_ALIVE_INTERVAL, 0);
     if (settings->sftp_keepalive == 1)
         guac_user_log(user, GUAC_LOG_WARNING, "The minimum allowed "
                 "value for keepalives by libssh2 is 2 seconds.");
diff --git a/src/protocols/vnc/settings.c b/src/protocols/vnc/settings.c
index 60e2f61c..a9e4228a 100644
--- a/src/protocols/vnc/settings.c
+++ b/src/protocols/vnc/settings.c
@@ -66,7 +66,7 @@ const char* GUAC_VNC_CLIENT_ARGS[] = {
     "sftp-private-key",
     "sftp-passphrase",
     "sftp-directory",
-    "sftp-keepalive",
+    "sftp-server-alive-interval",
 #endif
 
     "recording-path",
@@ -232,10 +232,10 @@ enum VNC_ARGS_IDX {
     /**
      * The interval at which SSH keepalive messages are sent to the server for
      * SFTP connections.  The default is 0 (disabling keepalives), and a value
-     * of 1 is automatically increased to 2 by libssh2 to avoid busy loop corner
+     * of 1 is automatically incremented to 2 by libssh2 to avoid busy loop corner
      * cases.
      */
-    IDX_SFTP_KEEPALIVE,
+    IDX_SFTP_SERVER_ALIVE_INTERVAL,
 #endif
 
     /**
@@ -408,7 +408,7 @@ guac_vnc_settings* guac_vnc_parse_args(guac_user* user,
     /* Default keepalive value */
     settings->sftp_keepalive =
         guac_user_parse_args_int(user, GUAC_VNC_CLIENT_ARGS, argv,
-                IDX_SFTP_KEEPALIVE, 0);
+                IDX_SFTP_SERVER_ALIVE_INTERVAL, 0);
     if (settings->sftp_keepalive == 1)
         guac_user_log(user, GUAC_LOG_WARNING, "The minimum allowed "
                 "value for keepalives by libssh2 is 2 seconds.");

From df718395e8a40f48aa863dafc9bfb902abc070ae Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Wed, 14 Jun 2017 10:17:28 -0400
Subject: [PATCH 11/20] GUACAMOLE-203: Change alive interval from int to
 unsigned.

---
 src/protocols/rdp/rdp.c          | 2 +-
 src/protocols/rdp/rdp_settings.c | 6 +++---
 src/protocols/rdp/rdp_settings.h | 2 +-
 src/protocols/ssh/settings.h     | 2 +-
 src/protocols/vnc/settings.c     | 6 +++---
 src/protocols/vnc/settings.h     | 2 +-
 src/protocols/vnc/vnc.c          | 2 +-
 7 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/src/protocols/rdp/rdp.c b/src/protocols/rdp/rdp.c
index 7b52a917..d06fad32 100644
--- a/src/protocols/rdp/rdp.c
+++ b/src/protocols/rdp/rdp.c
@@ -977,7 +977,7 @@ void* guac_rdp_client_thread(void* data) {
         /* Attempt SSH connection */
         rdp_client->sftp_session =
             guac_common_ssh_create_session(client, settings->sftp_hostname,
-                    settings->sftp_port, rdp_client->sftp_user, settings->sftp_keepalive);
+                    settings->sftp_port, rdp_client->sftp_user, settings->sftp_server_alive_interval);
 
         /* Fail if SSH connection does not succeed */
         if (rdp_client->sftp_session == NULL) {
diff --git a/src/protocols/rdp/rdp_settings.c b/src/protocols/rdp/rdp_settings.c
index 2b6635f8..98ecdbbf 100644
--- a/src/protocols/rdp/rdp_settings.c
+++ b/src/protocols/rdp/rdp_settings.c
@@ -785,12 +785,12 @@ guac_rdp_settings* guac_rdp_parse_args(guac_user* user,
                 IDX_SFTP_DIRECTORY, NULL);
 
     /* Default keepalive value */
-    settings->sftp_keepalive =
+    settings->sftp_server_alive_interval =
         guac_user_parse_args_int(user, GUAC_RDP_CLIENT_ARGS, argv,
                 IDX_SFTP_SERVER_ALIVE_INTERVAL, 0);
-    if (settings->sftp_keepalive == 1)
+    if (settings->sftp_server_alive_interval == 1)
         guac_user_log(user, GUAC_LOG_WARNING, "The minimum allowed "
-                "value for keepalives by libssh2 is 2 seconds.");
+                "value for keepalives is 2 seconds.");
 #endif
 
     /* Read recording path */
diff --git a/src/protocols/rdp/rdp_settings.h b/src/protocols/rdp/rdp_settings.h
index 47e5289a..e2013b7b 100644
--- a/src/protocols/rdp/rdp_settings.h
+++ b/src/protocols/rdp/rdp_settings.h
@@ -366,7 +366,7 @@ typedef struct guac_rdp_settings {
      * of 1 is automatically increased to 2 by libssh2 to avoid busy loop corner
      * cases.
      */
-    int sftp_keepalive;
+    unsigned sftp_server_alive_interval;
 #endif
 
     /**
diff --git a/src/protocols/ssh/settings.h b/src/protocols/ssh/settings.h
index e831d9e9..101caf70 100644
--- a/src/protocols/ssh/settings.h
+++ b/src/protocols/ssh/settings.h
@@ -189,7 +189,7 @@ typedef struct guac_ssh_settings {
     /**
      * The number of seconds between sending server alive messages.
      */
-    int server_alive_interval;
+    unsigned server_alive_interval;
 
 } guac_ssh_settings;
 
diff --git a/src/protocols/vnc/settings.c b/src/protocols/vnc/settings.c
index a9e4228a..cf1d8bca 100644
--- a/src/protocols/vnc/settings.c
+++ b/src/protocols/vnc/settings.c
@@ -406,12 +406,12 @@ guac_vnc_settings* guac_vnc_parse_args(guac_user* user,
                 IDX_SFTP_DIRECTORY, NULL);
 
     /* Default keepalive value */
-    settings->sftp_keepalive =
+    settings->sftp_server_alive_interval =
         guac_user_parse_args_int(user, GUAC_VNC_CLIENT_ARGS, argv,
                 IDX_SFTP_SERVER_ALIVE_INTERVAL, 0);
-    if (settings->sftp_keepalive == 1)
+    if (settings->sftp_server_alive_interval == 1)
         guac_user_log(user, GUAC_LOG_WARNING, "The minimum allowed "
-                "value for keepalives by libssh2 is 2 seconds.");
+                "value for keepalives is 2 seconds.");
 #endif
 
     /* Read recording path */
diff --git a/src/protocols/vnc/settings.h b/src/protocols/vnc/settings.h
index ba1bfdde..a9ce82c5 100644
--- a/src/protocols/vnc/settings.h
+++ b/src/protocols/vnc/settings.h
@@ -180,7 +180,7 @@ typedef struct guac_vnc_settings {
      * of 1 is automatically increased to 2 by libssh2 to avoid busy loop corner
      * cases.
      */
-    int sftp_keepalive;
+    unsigned sftp_server_alive_interval;
 #endif
 
     /**
diff --git a/src/protocols/vnc/vnc.c b/src/protocols/vnc/vnc.c
index 9aac436b..81d46f1b 100644
--- a/src/protocols/vnc/vnc.c
+++ b/src/protocols/vnc/vnc.c
@@ -261,7 +261,7 @@ void* guac_vnc_client_thread(void* data) {
         /* Attempt SSH connection */
         vnc_client->sftp_session =
             guac_common_ssh_create_session(client, settings->sftp_hostname,
-                    settings->sftp_port, vnc_client->sftp_user, settings->sftp_keepalive);
+                    settings->sftp_port, vnc_client->sftp_user, settings->sftp_server_alive_interval);
 
         /* Fail if SSH connection does not succeed */
         if (vnc_client->sftp_session == NULL) {

From 89b9a905db221da2b2c0c8c035141b3f4d8c15da Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Wed, 14 Jun 2017 11:11:32 -0400
Subject: [PATCH 12/20] GUACAMOLE-203: Tweak warning message sent to users.

---
 src/protocols/rdp/rdp_settings.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/protocols/rdp/rdp_settings.c b/src/protocols/rdp/rdp_settings.c
index 98ecdbbf..eebf9028 100644
--- a/src/protocols/rdp/rdp_settings.c
+++ b/src/protocols/rdp/rdp_settings.c
@@ -790,7 +790,7 @@ guac_rdp_settings* guac_rdp_parse_args(guac_user* user,
                 IDX_SFTP_SERVER_ALIVE_INTERVAL, 0);
     if (settings->sftp_server_alive_interval == 1)
         guac_user_log(user, GUAC_LOG_WARNING, "The minimum allowed "
-                "value for keepalives is 2 seconds.");
+                "value for keepalives is 2 seconds, this will be rounded up.");
 #endif
 
     /* Read recording path */

From af4d76214773187da5d93241c88dac05148502eb Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Wed, 14 Jun 2017 12:49:49 -0400
Subject: [PATCH 13/20] GUACAMOLE-203: Move warning about minimum alive
 interval to single place in common code.

---
 src/common-ssh/ssh.c             | 6 ++++++
 src/protocols/rdp/rdp_settings.c | 3 ---
 src/protocols/ssh/settings.c     | 3 ---
 src/protocols/vnc/settings.c     | 3 ---
 4 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/src/common-ssh/ssh.c b/src/common-ssh/ssh.c
index 3bff4b39..00f6327a 100644
--- a/src/common-ssh/ssh.c
+++ b/src/common-ssh/ssh.c
@@ -536,6 +536,12 @@ guac_common_ssh_session* guac_common_ssh_create_session(guac_client* client,
     if (keepalive > 0)
         libssh2_keepalive_config(common_session->session, 1, keepalive);
 
+    /* Warn if keepalive below minimum value */
+    if (keepalive == 1) {
+        guac_user_log(user, GUAC_LOG_WARNING, "keepalive interval will "
+            "be rounded up to minimum value of 2.");
+    }
+
     /* Return created session */
     return common_session;
 
diff --git a/src/protocols/rdp/rdp_settings.c b/src/protocols/rdp/rdp_settings.c
index eebf9028..f73ef9d9 100644
--- a/src/protocols/rdp/rdp_settings.c
+++ b/src/protocols/rdp/rdp_settings.c
@@ -788,9 +788,6 @@ guac_rdp_settings* guac_rdp_parse_args(guac_user* user,
     settings->sftp_server_alive_interval =
         guac_user_parse_args_int(user, GUAC_RDP_CLIENT_ARGS, argv,
                 IDX_SFTP_SERVER_ALIVE_INTERVAL, 0);
-    if (settings->sftp_server_alive_interval == 1)
-        guac_user_log(user, GUAC_LOG_WARNING, "The minimum allowed "
-                "value for keepalives is 2 seconds, this will be rounded up.");
 #endif
 
     /* Read recording path */
diff --git a/src/protocols/ssh/settings.c b/src/protocols/ssh/settings.c
index 98594153..8843923b 100644
--- a/src/protocols/ssh/settings.c
+++ b/src/protocols/ssh/settings.c
@@ -291,9 +291,6 @@ guac_ssh_settings* guac_ssh_parse_args(guac_user* user,
     settings->server_alive_interval =
         guac_user_parse_args_int(user, GUAC_SSH_CLIENT_ARGS, argv,
                 IDX_SERVER_ALIVE_INTERVAL, 0);
-    if (settings->server_alive_interval == 1)
-        guac_user_log(user, GUAC_LOG_WARNING, "Minimum keepalive interval "
-                " for libssh2 is 2 seconds.");
 
     /* Parsing was successful */
     return settings;
diff --git a/src/protocols/vnc/settings.c b/src/protocols/vnc/settings.c
index cf1d8bca..697466df 100644
--- a/src/protocols/vnc/settings.c
+++ b/src/protocols/vnc/settings.c
@@ -409,9 +409,6 @@ guac_vnc_settings* guac_vnc_parse_args(guac_user* user,
     settings->sftp_server_alive_interval =
         guac_user_parse_args_int(user, GUAC_VNC_CLIENT_ARGS, argv,
                 IDX_SFTP_SERVER_ALIVE_INTERVAL, 0);
-    if (settings->sftp_server_alive_interval == 1)
-        guac_user_log(user, GUAC_LOG_WARNING, "The minimum allowed "
-                "value for keepalives is 2 seconds.");
 #endif
 
     /* Read recording path */

From 8c24c77d555312d4227ab79713a5c2333a76c623 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Wed, 14 Jun 2017 13:00:30 -0400
Subject: [PATCH 14/20] GUACAMOLE-203: Change timer to timeout

---
 src/protocols/ssh/settings.h | 4 ++--
 src/protocols/ssh/ssh.c      | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/protocols/ssh/settings.h b/src/protocols/ssh/settings.h
index 101caf70..ea9f5ace 100644
--- a/src/protocols/ssh/settings.h
+++ b/src/protocols/ssh/settings.h
@@ -54,9 +54,9 @@
 #define GUAC_SSH_DEFAULT_RECORDING_NAME "recording"
 
 /**
- * The default polling timer for SSH activity in milliseconds.
+ * The default polling timeout for SSH activity in milliseconds.
  */
-#define GUAC_SSH_DEFAULT_POLL_TIMER 1000
+#define GUAC_SSH_DEFAULT_POLL_TIMEOUT 1000
 
 /**
  * Settings for the SSH connection. The values for this structure are parsed
diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index 59039bb6..afbfe331 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -343,7 +343,7 @@ void* ssh_client_thread(void* data) {
         }
         /* If keepalive is not configured, sleep for the default of 1 second */
         else
-            timer = GUAC_SSH_DEFAULT_POLL_TIMER;
+            timer = GUAC_SSH_DEFAULT_POLL_TIMEOUT;
 
         /* Read terminal data */
         bytes_read = libssh2_channel_read(ssh_client->term_channel,

From ed77114038dd7c6ef13517efe528b09074641d02 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Wed, 14 Jun 2017 13:01:01 -0400
Subject: [PATCH 15/20] GUACAMOLE-203: Fix issue using guac_client_log instead
 of guac_user_log.

---
 src/common-ssh/ssh.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/common-ssh/ssh.c b/src/common-ssh/ssh.c
index 00f6327a..50ab7e0b 100644
--- a/src/common-ssh/ssh.c
+++ b/src/common-ssh/ssh.c
@@ -538,7 +538,7 @@ guac_common_ssh_session* guac_common_ssh_create_session(guac_client* client,
 
     /* Warn if keepalive below minimum value */
     if (keepalive == 1) {
-        guac_user_log(user, GUAC_LOG_WARNING, "keepalive interval will "
+        guac_client_log(client, GUAC_LOG_WARNING, "keepalive interval will "
             "be rounded up to minimum value of 2.");
     }
 

From 05dfb1a6ae931564458ba6f66360bd12a9ae783f Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Sun, 25 Jun 2017 04:49:05 -0400
Subject: [PATCH 16/20] GUACAMOLE-203: Deal correctly with negative keepalive
 values.

---
 src/common-ssh/ssh.c             | 14 +++++++++-----
 src/protocols/rdp/rdp_settings.h |  2 +-
 src/protocols/ssh/settings.h     |  2 +-
 src/protocols/vnc/settings.h     |  2 +-
 4 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/src/common-ssh/ssh.c b/src/common-ssh/ssh.c
index 50ab7e0b..d7da64a8 100644
--- a/src/common-ssh/ssh.c
+++ b/src/common-ssh/ssh.c
@@ -532,16 +532,20 @@ guac_common_ssh_session* guac_common_ssh_create_session(guac_client* client,
         return NULL;
     }
 
-    /* Configure session keepalive */
-    if (keepalive > 0)
-        libssh2_keepalive_config(common_session->session, 1, keepalive);
-
     /* Warn if keepalive below minimum value */
-    if (keepalive == 1) {
+    if (keepalive < 0) {
+        keepalive = 0;
+        guac_client_log(client, GUAC_LOG_WARNING, "negative keepalive intervals "
+            "are converted to 0, disabling keepalive.");
+    }
+    else if(keepalive == 1) {
         guac_client_log(client, GUAC_LOG_WARNING, "keepalive interval will "
             "be rounded up to minimum value of 2.");
     }
 
+    /* Configure session keepalive */
+    libssh2_keepalive_config(common_session->session, 1, keepalive);
+
     /* Return created session */
     return common_session;
 
diff --git a/src/protocols/rdp/rdp_settings.h b/src/protocols/rdp/rdp_settings.h
index e2013b7b..8edb79e4 100644
--- a/src/protocols/rdp/rdp_settings.h
+++ b/src/protocols/rdp/rdp_settings.h
@@ -366,7 +366,7 @@ typedef struct guac_rdp_settings {
      * of 1 is automatically increased to 2 by libssh2 to avoid busy loop corner
      * cases.
      */
-    unsigned sftp_server_alive_interval;
+    int sftp_server_alive_interval;
 #endif
 
     /**
diff --git a/src/protocols/ssh/settings.h b/src/protocols/ssh/settings.h
index ea9f5ace..f49d054d 100644
--- a/src/protocols/ssh/settings.h
+++ b/src/protocols/ssh/settings.h
@@ -189,7 +189,7 @@ typedef struct guac_ssh_settings {
     /**
      * The number of seconds between sending server alive messages.
      */
-    unsigned server_alive_interval;
+    int server_alive_interval;
 
 } guac_ssh_settings;
 
diff --git a/src/protocols/vnc/settings.h b/src/protocols/vnc/settings.h
index a9ce82c5..3c7b2587 100644
--- a/src/protocols/vnc/settings.h
+++ b/src/protocols/vnc/settings.h
@@ -180,7 +180,7 @@ typedef struct guac_vnc_settings {
      * of 1 is automatically increased to 2 by libssh2 to avoid busy loop corner
      * cases.
      */
-    unsigned sftp_server_alive_interval;
+    int sftp_server_alive_interval;
 #endif
 
     /**

From 711cdd69298fddeff8a641bcb21aab401ea5e59f Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Sun, 25 Jun 2017 05:13:12 -0400
Subject: [PATCH 17/20] GUACAMOLE-203: Allow keepalive param to be modified
 inside the function.

---
 src/common-ssh/ssh.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/common-ssh/ssh.c b/src/common-ssh/ssh.c
index d7da64a8..00c9f948 100644
--- a/src/common-ssh/ssh.c
+++ b/src/common-ssh/ssh.c
@@ -414,7 +414,7 @@ static int guac_common_ssh_authenticate(guac_common_ssh_session* common_session)
 }
 
 guac_common_ssh_session* guac_common_ssh_create_session(guac_client* client,
-        const char* hostname, const char* port, guac_common_ssh_user* user, const int keepalive) {
+        const char* hostname, const char* port, guac_common_ssh_user* user, int keepalive) {
 
     int retval;
 

From 041fcc4651613a383e4d208e603486072ed81594 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Sun, 25 Jun 2017 05:13:22 -0400
Subject: [PATCH 18/20] GUACAMOLE-203: Change remaining instances of timer to
 timeout.

---
 src/protocols/ssh/ssh.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/protocols/ssh/ssh.c b/src/protocols/ssh/ssh.c
index afbfe331..aa9fdaee 100644
--- a/src/protocols/ssh/ssh.c
+++ b/src/protocols/ssh/ssh.c
@@ -323,8 +323,8 @@ void* ssh_client_thread(void* data) {
         /* Track total amount of data read */
         int total_read = 0;
 
-        /* Timer for polling socket activity */
-        int timer;
+        /* Timeout for polling socket activity */
+        int timeout;
 
         pthread_mutex_lock(&(ssh_client->term_channel_lock));
 
@@ -336,14 +336,14 @@ void* ssh_client_thread(void* data) {
 
         /* Send keepalive at configured interval */
         if (settings->server_alive_interval > 0) {
-            int timeout = 0;
+            timeout = 0;
             if (libssh2_keepalive_send(ssh_client->session->session, &timeout) > 0)
                 break;
-            timer = timeout * 1000;
+            timeout *= 1000;
         }
         /* If keepalive is not configured, sleep for the default of 1 second */
         else
-            timer = GUAC_SSH_DEFAULT_POLL_TIMEOUT;
+            timeout = GUAC_SSH_DEFAULT_POLL_TIMEOUT;
 
         /* Read terminal data */
         bytes_read = libssh2_channel_read(ssh_client->term_channel,
@@ -384,8 +384,8 @@ void* ssh_client_thread(void* data) {
                 .revents = 0,
             }};
 
-            /* Wait up to computed timer */
-            if (poll(fds, 1, timer) < 0)
+            /* Wait up to computed timeout */
+            if (poll(fds, 1, timeout) < 0)
                 break;
 
         }

From 650f7a0a320cb9c3834cfff2a53c890b529c9577 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Sun, 25 Jun 2017 14:10:42 -0400
Subject: [PATCH 19/20] GUACAMOLE-203: if is not a function...

---
 src/common-ssh/ssh.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/common-ssh/ssh.c b/src/common-ssh/ssh.c
index 00c9f948..cec3d538 100644
--- a/src/common-ssh/ssh.c
+++ b/src/common-ssh/ssh.c
@@ -538,7 +538,7 @@ guac_common_ssh_session* guac_common_ssh_create_session(guac_client* client,
         guac_client_log(client, GUAC_LOG_WARNING, "negative keepalive intervals "
             "are converted to 0, disabling keepalive.");
     }
-    else if(keepalive == 1) {
+    else if (keepalive == 1) {
         guac_client_log(client, GUAC_LOG_WARNING, "keepalive interval will "
             "be rounded up to minimum value of 2.");
     }

From a5efbb593327544b62996f14c2080ad14e152439 Mon Sep 17 00:00:00 2001
From: Nick Couchman <vnick@apache.org>
Date: Sun, 25 Jun 2017 14:56:50 -0400
Subject: [PATCH 20/20] GUACAMOLE-203: Fix function prototype to remove const.

---
 src/common-ssh/common-ssh/ssh.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/common-ssh/common-ssh/ssh.h b/src/common-ssh/common-ssh/ssh.h
index ff8621e9..8026549d 100644
--- a/src/common-ssh/common-ssh/ssh.h
+++ b/src/common-ssh/common-ssh/ssh.h
@@ -98,7 +98,7 @@ void guac_common_ssh_uninit();
  *     if the connection or authentication were not successful.
  */
 guac_common_ssh_session* guac_common_ssh_create_session(guac_client* client,
-        const char* hostname, const char* port, guac_common_ssh_user* user, const int keepalive);
+        const char* hostname, const char* port, guac_common_ssh_user* user, int keepalive);
 
 /**
  * Disconnects and destroys the given SSH session, freeing all associated