[RFC,v1,03/10] dts: ssh connection additions for hello world

diff --git a/dts/framework/ssh_connection.py b/dts/framework/ssh_connection.py
index bbf7c8ef01..ec7333e565 100644
--- a/dts/framework/ssh_connection.py
+++ b/dts/framework/ssh_connection.py
@@ -8,6 +8,7 @@ 
 from typing import Any, Optional
 
 from .logger import DTSLOG
+from .settings import SETTINGS
 from .ssh_pexpect import SSHPexpect
 
 
@@ -68,3 +69,21 @@  def close(self, force: bool = False) -> None:
             self.logger.logger_exit()
 
         self.session.close(force)
+
+    def check_available(self) -> bool:
+        MAGIC_STR = "DTS_CHECK_SESSION"
+        out = self.session.send_command("echo %s" % MAGIC_STR, timeout=0.1)
+        # if not available, try to send ^C and check again
+        if MAGIC_STR not in out:
+            self.logger.info("Try to recover session...")
+            self.session.send_command("^C", timeout=SETTINGS.timeout)
+            out = self.session.send_command("echo %s" % MAGIC_STR, timeout=0.1)
+            if MAGIC_STR not in out:
+                return False
+
+        return True
+
+    def copy_file_to(
+        self, src: str, dst: str = "~/", password: str = "", node_session: Any = None
+    ) -> None:
+        self.session.copy_file_to(src, dst, password, node_session)
diff --git a/dts/framework/ssh_pexpect.py b/dts/framework/ssh_pexpect.py
index e8f64515c0..b8eb10025e 100644
--- a/dts/framework/ssh_pexpect.py
+++ b/dts/framework/ssh_pexpect.py
@@ -5,11 +5,16 @@ 
 #
 
 import time
-from typing import Optional
+from typing import Any, Optional
 
+import pexpect
 from pexpect import pxssh
 
-from .exception import SSHConnectionException, SSHSessionDeadException, TimeoutException
+from .exception import (
+    SSHConnectionException,
+    SSHSessionDeadException,
+    TimeoutException,
+)
 from .logger import DTSLOG
 from .utils import GREEN, RED
 
@@ -203,3 +208,55 @@  def close(self, force: bool = False) -> None:
 
     def isalive(self) -> bool:
         return self.session.isalive()
+
+    def copy_file_to(
+        self, src: str, dst: str = "~/", password: str = "", node_session: Any = None
+    ) -> None:
+        """
+        Sends a local file to a remote place.
+        """
+        command: str
+        if ":" in self.node:
+            command = "scp -v -P {0} -o NoHostAuthenticationForLocalhost=yes {1} {2}@{3}:{4}".format(
+                str(self.port), src, self.username, self.ip, dst
+            )
+        else:
+            command = "scp -v {0} {1}@{2}:{3}".format(
+                src, self.username, self.node, dst
+            )
+        if password == "":
+            self._spawn_scp(command, self.password, node_session)
+        else:
+            self._spawn_scp(command, password, node_session)
+
+    def _spawn_scp(self, scp_cmd: str, password: str, node_session: Any) -> None:
+        """
+        Transfer a file with SCP
+        """
+        self.logger.info(scp_cmd)
+        # if node_session is not None, copy file from/to node env
+        # if node_session is None, copy file from/to current dts env
+        p: pexpect.spawn
+        if node_session is not None:
+            node_session.session.clean_session()
+            node_session.session.__sendline(scp_cmd)
+            p = node_session.session.session
+        else:
+            p = pexpect.spawn(scp_cmd)
+        time.sleep(0.5)
+        ssh_newkey: str = "Are you sure you want to continue connecting"
+        i: int = p.expect(
+            [ssh_newkey, "[pP]assword", "# ", pexpect.EOF, pexpect.TIMEOUT], 120
+        )
+        if i == 0:  # add once in trust list
+            p.sendline("yes")
+            i = p.expect([ssh_newkey, "[pP]assword", pexpect.EOF], 2)
+
+        if i == 1:
+            time.sleep(0.5)
+            p.sendline(password)
+            p.expect("Exit status 0", 60)
+        if i == 4:
+            self.logger.error("SCP TIMEOUT error %d" % i)
+        if node_session is None:
+            p.close()