fix(get_config): socket-level timeout for SSH fallback — covers KEX phase

paramiko banner_timeout/auth_timeout do not cover kex negotiation.
Using raw socket with settimeout(8) ensures the entire SSH handshake
is bounded, preventing the poll from hanging and timing out.

napalm_procurve/procurve.py

@@ -592,53 +592,50 @@ class ProcurveDriver(ConfigLifecycleMixin, SwitchDriver):
         Used as fallback when the REST API does not expose the config endpoint
         (e.g. HP 2530 / YA firmware with Mocana SSH).
 
-        Uses paramiko directly (not netmiko) to:
-        - Explicitly enable diffie-hellman-group1-sha1 (required by Mocana SSH 6.3)
-        - Keep total blocking time ≤ 10 seconds
+        Uses a raw socket with settimeout() so the timeout covers ALL phases of
+        the SSH handshake (TCP connect, banner, KEX, auth) — not just TCP connect.
+        This is the only reliable way to prevent a hanging KEX from blocking
+        indefinitely inside the poll task.
         """
+        import socket as _socket
+
         import paramiko
 
-        _FALLBACK_TIMEOUT = 8
+        _FALLBACK_TIMEOUT = 8  # seconds — covers the entire SSH session
 
-        # KEX list that includes the old group1-sha1 required by Mocana SSH 6.3
         _LEGACY_KEX = [
             "diffie-hellman-group1-sha1",
             "diffie-hellman-group14-sha1",
             "diffie-hellman-group14-sha256",
-            "diffie-hellman-group-exchange-sha256",
         ]
-        _LEGACY_DISABLED = {
-            "pubkeys": ["rsa-sha2-256", "rsa-sha2-512"],
-        }
 
         try:
-            client = paramiko.SSHClient()
-            client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
+            sock = _socket.create_connection(
+                (self.hostname, self.port or 22),
+                timeout=_FALLBACK_TIMEOUT,
+            )
+            sock.settimeout(_FALLBACK_TIMEOUT)  # applies to all recv/send including KEX
 
-            # Patch the preferred kex list on the class before connecting so
-            # paramiko will negotiate group1-sha1 with the old Mocana SSH server.
-            orig_kex = paramiko.Transport._preferred_kex
-            try:
-                paramiko.Transport._preferred_kex = tuple(_LEGACY_KEX)
-                client.connect(
-                    hostname=self.hostname,
-                    port=self.port or 22,
-                    username=self.username,
-                    password=self.password,
-                    timeout=_FALLBACK_TIMEOUT,
-                    banner_timeout=_FALLBACK_TIMEOUT,
-                    auth_timeout=_FALLBACK_TIMEOUT,
-                    look_for_keys=False,
-                    allow_agent=False,
-                    disabled_algorithms=_LEGACY_DISABLED,
-                )
-            finally:
-                paramiko.Transport._preferred_kex = orig_kex
+            transport = paramiko.Transport(sock)
+            transport.get_security_options().kex = _LEGACY_KEX
+            transport.connect(
+                username=self.username,
+                password=self.password,
+            )
 
-            _, stdout, _ = client.exec_command("show running-config", timeout=_FALLBACK_TIMEOUT)
-            config = stdout.read().decode("utf-8", errors="replace")
-            client.close()
-            return config
+            channel = transport.open_session()
+            channel.settimeout(_FALLBACK_TIMEOUT)
+            channel.exec_command("show running-config")
+
+            chunks: list[bytes] = []
+            while True:
+                data = channel.recv(4096)
+                if not data:
+                    break
+                chunks.append(data)
+
+            transport.close()
+            return b"".join(chunks).decode("utf-8", errors="replace")
         except Exception as exc:
             logger.warning("SSH config fallback failed for %s: %s", self.hostname, exc)
             return ""