fix(hwfit): validate remote SSH detection targets (#3718)

routes/_validators.py

@@ -0,0 +1,31 @@
+import re
+
+from fastapi import HTTPException
+
+
+_REMOTE_HOST_RE = re.compile(
+    r"^(?:[A-Za-z0-9][A-Za-z0-9._-]*@)?[A-Za-z0-9][A-Za-z0-9._-]*$"
+)
+_SSH_PORT_RE = re.compile(r"^\d{1,5}$")
+
+
+def validate_remote_host(v: str | None) -> str | None:
+    if v is None or v == "":
+        return None
+    if not _REMOTE_HOST_RE.match(v):
+        raise HTTPException(
+            400,
+            "Invalid remote_host — must be host or user@host, no SSH option syntax",
+        )
+    return v
+
+
+def validate_ssh_port(v: str | None) -> str | None:
+    if v is None or v == "":
+        return None
+    if not _SSH_PORT_RE.fullmatch(str(v)):
+        raise HTTPException(400, "Invalid ssh_port")
+    port = int(v)
+    if port < 1 or port > 65535:
+        raise HTTPException(400, "Invalid ssh_port")
+    return str(port)