From 194e64244824eee9fd37fc8fa0605fef26f951ba Mon Sep 17 00:00:00 2001
From: terrafrost <terrafrost@gmail.com>
Date: Tue, 15 Dec 2020 08:25:42 -0600
Subject: [PATCH] SSH2: handle keepalive@openssh.com packets

---
 phpseclib/Net/SSH2.php | 112 +++++++++++++++++++++++------------------
 1 file changed, 62 insertions(+), 50 deletions(-)

diff --git a/phpseclib/Net/SSH2.php b/phpseclib/Net/SSH2.php
index 17125801..ce007b06 100644
--- a/phpseclib/Net/SSH2.php
+++ b/phpseclib/Net/SSH2.php
@@ -3351,6 +3351,57 @@ class Net_SSH2
      */
     function _get_binary_packet($skip_channel_filter = false)
     {
+        if ($skip_channel_filter) {
+            $read = array($this->fsock);
+            $write = $except = null;
+
+            if ($this->curTimeout <= 0) {
+                if ($this->keepAlive <= 0) {
+                    @stream_select($read, $write, $except, null);
+                } else {
+                    if (!@stream_select($read, $write, $except, $this->keepAlive) && !count($read)) {
+                        $this->_send_binary_packet(pack('CN', NET_SSH2_MSG_IGNORE, 0));
+                        return $this->_get_binary_packet(true);
+                    }
+                }
+            } else {
+                if ($this->curTimeout < 0) {
+                    $this->is_timeout = true;
+                    return true;
+                }
+
+                $read = array($this->fsock);
+                $write = $except = null;
+
+                $start = strtok(microtime(), ' ') + strtok(''); // http://php.net/microtime#61838
+
+                if ($this->keepAlive > 0 && $this->keepAlive < $this->curTimeout) {
+                    if (!@stream_select($read, $write, $except, $this->keepAlive) && !count($read)) {
+                        $this->_send_binary_packet(pack('CN', NET_SSH2_MSG_IGNORE, 0));
+                        $elapsed = strtok(microtime(), ' ') + strtok('') - $start;
+                        $this->curTimeout-= $elapsed;
+                        return $this->_get_binary_packet(true);
+                    }
+                    $elapsed = strtok(microtime(), ' ') + strtok('') - $start;
+                    $this->curTimeout-= $elapsed;
+                }
+
+                $sec = floor($this->curTimeout);
+                $usec = 1000000 * ($this->curTimeout - $sec);
+
+                // on windows this returns a "Warning: Invalid CRT parameters detected" error
+                if (!@stream_select($read, $write, $except, $sec, $usec) && !count($read)) {
+                    $this->is_timeout = true;
+                    if ($client_channel == NET_SSH2_CHANNEL_EXEC && !$this->request_pty) {
+                        $this->_close_channel($client_channel);
+                    }
+                    return true;
+                }
+                $elapsed = strtok(microtime(), ' ') + strtok('') - $start;
+                $this->curTimeout-= $elapsed;
+            }
+        }
+
         if (!is_resource($this->fsock) || feof($this->fsock)) {
             $this->bitmap = 0;
             user_error('Connection closed prematurely');
@@ -3502,9 +3553,19 @@ class Net_SSH2
         // only called when we've already logged in
         if (($this->bitmap & NET_SSH2_MASK_CONNECTED) && $this->isAuthenticated()) {
             switch (ord($payload[0])) {
+                case NET_SSH2_MSG_CHANNEL_REQUEST:
+                    if (strlen($payload) == 31) {
+                        extract(unpack('cpacket_type/Nchannel/Nlength', $payload));
+                        if (substr($payload, 9, $length) == 'keepalive@openssh.com' && isset($this->server_channels[$channel])) {
+                            if (ord(substr($payload, 9 + $length))) { // want reply
+                                $this->_send_binary_packet(pack('CN', NET_SSH2_MSG_CHANNEL_SUCCESS, $this->server_channels[$channel]));
+                            }
+                            $payload = $this->_get_binary_packet($skip_channel_filter);
+                        }
+                    }
+                    break;
                 case NET_SSH2_MSG_CHANNEL_DATA:
                 case NET_SSH2_MSG_CHANNEL_EXTENDED_DATA:
-                case NET_SSH2_MSG_CHANNEL_REQUEST:
                 case NET_SSH2_MSG_CHANNEL_CLOSE:
                 case NET_SSH2_MSG_CHANNEL_EOF:
                     if (!$skip_channel_filter && !empty($this->server_channels)) {
@@ -3702,55 +3763,6 @@ class Net_SSH2
                 $response = $this->binary_packet_buffer;
                 $this->binary_packet_buffer = false;
             } else {
-                $read = array($this->fsock);
-                $write = $except = null;
-
-                if ($this->curTimeout <= 0) {
-                    if ($this->keepAlive <= 0) {
-                        @stream_select($read, $write, $except, null);
-                    } else {
-                        if (!@stream_select($read, $write, $except, $this->keepAlive) && !count($read)) {
-                            $this->_send_binary_packet(pack('CN', NET_SSH2_MSG_IGNORE, 0));
-                            continue;
-                        }
-                    }
-                } else {
-                    if ($this->curTimeout < 0) {
-                        $this->is_timeout = true;
-                        return true;
-                    }
-
-                    $read = array($this->fsock);
-                    $write = $except = null;
-
-                    $start = strtok(microtime(), ' ') + strtok(''); // http://php.net/microtime#61838
-
-                    if ($this->keepAlive > 0 && $this->keepAlive < $this->curTimeout) {
-                        if (!@stream_select($read, $write, $except, $this->keepAlive) && !count($read)) {
-                            $this->_send_binary_packet(pack('CN', NET_SSH2_MSG_IGNORE, 0));
-                            $elapsed = strtok(microtime(), ' ') + strtok('') - $start;
-                            $this->curTimeout-= $elapsed;
-                            continue;
-                        }
-                        $elapsed = strtok(microtime(), ' ') + strtok('') - $start;
-                        $this->curTimeout-= $elapsed;
-                    }
-
-                    $sec = floor($this->curTimeout);
-                    $usec = 1000000 * ($this->curTimeout - $sec);
-
-                    // on windows this returns a "Warning: Invalid CRT parameters detected" error
-                    if (!@stream_select($read, $write, $except, $sec, $usec) && !count($read)) {
-                        $this->is_timeout = true;
-                        if ($client_channel == NET_SSH2_CHANNEL_EXEC && !$this->request_pty) {
-                            $this->_close_channel($client_channel);
-                        }
-                        return true;
-                    }
-                    $elapsed = strtok(microtime(), ' ') + strtok('') - $start;
-                    $this->curTimeout-= $elapsed;
-                }
-
                 $response = $this->_get_binary_packet(true);
                 if ($response === false) {
                     $this->bitmap = 0;