test: Verify fetching data using ssh public key

Add a test case to verify that a new (guest) user can retrieve data
(i.e. syslog data) using ssh public key

Fixes #304

test/case/ietf_system/ietf_system.yaml

@@ -13,3 +13,6 @@
 
 - name: timezone_utc_offset
   case: timezone_utc_offset/test.py
+
+- name: ssh_key_authentication
+  case: ssh_key_authentication/test.py

test/case/ietf_system/ssh_key_authentication/test.py

@@ -0,0 +1,94 @@
+#!/usr/bin/env python3
+"""
+Generate ssh key pair
+
+Verify that 'guest' user can fetch data using only the 'public' key
+"""
+
+import infamy
+import os
+import tempfile
+from infamy import ssh
+
+with infamy.Test() as test:
+    with test.step("Connect to the target device"):
+        env = infamy.Env()
+        target = env.attach("target", "mgmt")
+
+        private_key = """-----BEGIN OPENSSH PRIVATE KEY-----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+-----END OPENSSH PRIVATE KEY-----
+"""       
+
+        public_key_alg = "ssh-rsa"
+        public_key_data = "AAAAB3NzaC1yc2EAAAADAQABAAABAQCffMvdK1VBkuw/12etfEr89Piba2NbQz7YY3ol2IhRnIoj0oodZp/a4c11c1Q+jQkbCDKPWB45w3ZMR2Q93XXeY72qtLzvCBLOzeCkX3czMAJLLxznl3EXmDnTAWetE1nUmByLLOvKdw1CPFiS9tushwdfj6iOfex3HvQwltV5i/rQz0h7JeSwEQ0Xn6sBgDxWlD6TtwYl4ch0zHoxRHCjqdQig7NMonhaF53BMKRYaUSLET3w+zKfK8HYiHxry6Jf+dcts9PQyxpCiEW3RoU65nwnq1pG7XAdmT/DeGKSQqXkdnmXvgZkrQYZ+4HW2veQlHzwwEIAhMTscS+QiOX/"
+
+    with test.step("Create a guest user on the target device"):
+        USER = "guest"
+
+        target.put_config_dict("ietf-system", {
+            "system": {
+                "authentication": {
+                    "user": [
+                        {
+                            "name": USER,
+                            "authorized-key": [
+                                {
+                                    "name":"guest-ssh-key",
+                                    "algorithm":public_key_alg,
+                                    "key-data":public_key_data
+                                }
+                            ],
+                            "infix-system:shell":"bash"
+                        }
+                    ]
+                }
+            }
+        })
+
+    with test.step("Write private key to a temporary file"):
+        with tempfile.NamedTemporaryFile(delete=False, mode='w') as key_file:
+            key_file.write(private_key)
+            key_file_name = key_file.name
+
+        os.chmod(key_file_name, 0o600)
+
+    with test.step("Verify it is possible to fetch syslog data using public key"):
+        address = target.get_mgmt_ip()
+        syslog_file = "./syslog_copy"
+
+        ssh.fetch_file(
+            remote_user=USER,
+            remote_address=address,
+            remote_file="/var/log/syslog",
+            local_file=syslog_file,
+            key_file=key_file_name,
+            check=True,
+            remove=True
+        )
+
+    test.succeed()

test/case/ietf_system/ssh_key_authentication/topology.dot

@@ -0,0 +1 @@
+../../../infamy/topologies/1x1.dot

test/infamy/ssh.py

@@ -12,6 +12,55 @@ class Location:
     port: int = 22
 
 
+import subprocess
+import os
+
+def fetch_file(remote_user, remote_address, remote_file, local_file, key_file, check=False, remove=False):
+    """
+    Fetches a file over SSH using scp and the provided private key.
+    
+    :param remote_user: The user on the remote machine.
+    :param remote_address: The address of the remote machine.
+    :param remote_file: The file to fetch from the remote machine.
+    :param local_file: The local path where the file will be stored.
+    :param key_file: The path to the private SSH key.
+    :param check: check the return code of the command.
+    :param remove: remove the fetched local file after copying.
+    """
+    try:
+        result = subprocess.run(
+            f"scp -q -o StrictHostKeyChecking=no -i {key_file} {remote_user}@[{remote_address}]:{remote_file} {local_file}",
+            shell=True
+        )
+
+        if check:
+            if result.returncode != 0:
+                raise RuntimeError("Failed to copy file from remote host")
+
+            if not os.path.exists(local_file):
+                raise RuntimeError(f"File {local_file} does not exist after copy")
+
+            if os.path.getsize(local_file) == 0:
+                raise RuntimeError(f"File {local_file} is empty after copy")
+
+    except Exception as e:
+        print(f"Error during file transfer: {e}")
+        raise
+
+    finally:
+        if os.path.exists(key_file):
+            try:
+                os.remove(key_file)
+            except OSError as e:
+                print(f"Error removing key file {key_file}: {e}")
+
+    if remove:
+        try:
+            if os.path.exists(local_file):
+                os.remove(local_file)
+        except OSError as e:
+            print(f"Error removing fetched file {local_file}: {e}")
+
 class Device(object):
     def __init__(self, name: str, location: Location):
         self.name = name