#2710 - Initial implementation f the receive/send methods. Committing to change branch

src/primaite/simulator/network/hardware/nodes/host/host_node.py

@@ -293,6 +293,7 @@ class HostNode(Node):
         * DNS (Domain Name System) Client: Resolves domain names to IP addresses.
         * FTP (File Transfer Protocol) Client: Enables file transfers between the host and FTP servers.
         * NTP (Network Time Protocol) Client: Synchronizes the system clock with NTP servers.
+        * Terminal Client: Handles SSH requests between HostNode and external components.
 
     Applications:
     ------------

src/primaite/simulator/system/services/terminal/terminal.py

@@ -2,14 +2,14 @@
 from __future__ import annotations
 
 from ipaddress import IPv4Address
-from typing import Dict, List, Optional
+from typing import Any, Dict, List, Optional
 from uuid import uuid4
 
 from pydantic import BaseModel
 
 from primaite.interface.request import RequestResponse
 from primaite.simulator.core import RequestManager
-from primaite.simulator.network.hardware.nodes.host.host_node import HostNode
+from primaite.simulator.network.hardware.base import Node
 from primaite.simulator.network.protocols.ssh import SSHConnectionMessage, SSHPacket, SSHTransportMessage
 from primaite.simulator.network.transmission.network_layer import IPProtocol
 from primaite.simulator.network.transmission.transport_layer import Port
@@ -27,7 +27,7 @@ class TerminalClientConnection(BaseModel):
     connection_id: str
     """Connection UUID."""
 
-    parent_node: HostNode
+    parent_node: Node   # Technically I think this should be HostNode, but that causes a circular import.
     """The parent Node that this connection was created on."""
 
     is_active: bool = True
@@ -116,7 +116,7 @@ class Terminal(Service):
             self.process_login(dest_ip_address=dest_ip_address, user_account=user_account)
 
     def _ssh_process_login(self, dest_ip_address: IPv4Address, user_account: dict, **kwargs) -> bool:
-        """Processes the login attempt. Returns a SSHPacket which either rejects the login or accepts it."""
+        """Processes the login attempt. Returns a bool which either rejects the login or accepts it."""
         # we assume that the login fails unless we meet all the criteria.
         transport_message = SSHTransportMessage.SSH_MSG_USERAUTH_FAILURE
         connection_message = SSHConnectionMessage.SSH_MSG_CHANNEL_OPEN_FAILED
@@ -142,6 +142,56 @@ class Terminal(Service):
         self.send(payload=payload, dest_ip_address=dest_ip_address)
         return True
 
+    def validate_user(self, user: Dict[str]) -> bool:
+        return True if user.get("username") in self.user_connections else False
+
+
+    def _ssh_process_logoff(self, dest_ip_address: IPv4Address, user_account: dict, **kwargs) -> bool:
+        """Process the logoff attempt. Return a bool if succesful or unsuccessful."""
+        
+        if self.validate_user(user_account):
+            # Account is logged in
+            self.user_connections.pop[user_account["username"]] # assumption atm
+            self.is_connected = False
+            return True
+        else:
+            self.sys_log.warning("User account credentials invalid.")
+
+    def _ssh_process_command(self, session_id: str, *args, **kwargs) -> bool:
+        return True
+
+    def send_logoff_ack(self):
+        """Send confirmation of successful disconnect"""
+        transport_message = SSHTransportMessage.SSH_MSG_SERVICE_SUCCESS
+        connection_message = SSHConnectionMessage.SSH_MSG_CHANNEL_CLOSE
+        payload: SSHPacket = SSHPacket(transport_message=transport_message, connection_message=connection_message, ssh_output=RequestResponse(status="success"))
+        self.send(payload=payload)
+
+    def receive(self, payload: SSHPacket, session_id: str, **kwargs) -> bool:
+            self.sys_log.debug(f"Received payload: {payload} from session: {session_id}")
+            if payload.connection_message ==SSHConnectionMessage. SSH_MSG_CHANNEL_CLOSE:
+                result = self._ssh_process_logoff(session_id=session_id)  
+                # We need to close on the other machine as well
+                self.send_logoff_ack()
+
+            elif payload.transport_message == SSHTransportMessage.SSH_MSG_USERAUTH_REQUEST:
+                src_ip = kwargs.get("frame").ip.src_ip_address
+                user_account = payload.get("user_account", {})
+                result = self._ssh_process_login(src_ip=src_ip, session_id=session_id, user_account=user_account)
+
+            elif payload.transport_message == SSHTransportMessage.SSH_MSG_SERVICE_REQUEST:
+                # Ensure we only ever process requests if we have a established connection (e.g session_id is provided and validated)
+                result = self._ssh_process_command(session_id=session_id)
+
+            else:
+                self.sys_log.warning("Encounter unexpected message type, rejecting connection")
+                # send a SSH_MSG_CHANNEL_CLOSE if there is a session_id otherwise SSH_MSG_OPEN_FAILED
+                return False
+
+            self.send(payload=result, session_id=session_id)
+            return True
+
+
     # %% Outbound
 
     def login(self, dest_ip_address: IPv4Address) -> bool:
@@ -217,3 +267,13 @@ class Terminal(Service):
         )
         self.connected = False
         return True
+
+
+    def send(
+            self,
+            payload: SSHPacket,
+            dest_ip_address: Optional[IPv4Address] = None,
+            session_id: Optional[str] = None,
+        ) -> bool:
+            return super().send(payload=payload, dest_ip_address=dest_ip_address, dest_port=Port.SSH, session_id=session_id)
+