28 lines
1.2 KiB
Python
28 lines
1.2 KiB
Python
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"""Single-principal stdio credentials; never use this for a shared MCP listener."""
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from pathlib import Path
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class StdioTokenFile:
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"""Reread an operator-projected Hub-audience credential for every request.
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This does not mint credentials or authenticate multiple callers. The process
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and its private stdio transport must belong to the one admitted principal.
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The Hub API validates issuer/audience/expiry and current authority.
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"""
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def __init__(self, path: Path):
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if not path.is_absolute():
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raise ValueError("absolute MCP credential path required")
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self.path = path
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def __call__(self) -> str:
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# A bounded read prevents an accidentally mounted large file from being
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# loaded. Errors are sanitized by the MCP HTTP adapter.
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with self.path.open("r", encoding="ascii") as stream:
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raw = stream.read(16386)
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if len(raw) > 16385:
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raise ValueError("current stdio credential unavailable")
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value = raw.strip()
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if not value or len(value) > 16384 or any(c.isspace() for c in value):
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raise ValueError("current stdio credential unavailable")
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return value
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