kopia lustrzana https://github.com/tsileo/little-boxes
104 wiersze
3.3 KiB
Python
104 wiersze
3.3 KiB
Python
"""Implements HTTP signature for Flask requests.
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Mastodon instances won't accept requests that are not signed using this scheme.
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"""
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import base64
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import hashlib
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import logging
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from datetime import datetime
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from typing import Any
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from typing import Dict
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from typing import Optional
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from urllib.parse import urlparse
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from Crypto.Hash import SHA256
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from Crypto.Signature import PKCS1_v1_5
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from flask import request
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from requests.auth import AuthBase
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logger = logging.getLogger(__name__)
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# FIXME(tsileo): no more Flask
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def _build_signed_string(
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signed_headers: str, method: str, path: str, headers: Any, body_digest: str
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) -> str:
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out = []
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for signed_header in signed_headers.split(" "):
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if signed_header == "(request-target)":
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out.append("(request-target): " + method.lower() + " " + path)
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elif signed_header == "digest":
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out.append("digest: " + body_digest)
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else:
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out.append(signed_header + ": " + headers[signed_header])
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return "\n".join(out)
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def _parse_sig_header(val: Optional[str]) -> Optional[Dict[str, str]]:
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if not val:
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return None
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out = {}
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for data in val.split(","):
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k, v = data.split("=", 1)
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out[k] = v[1 : len(v) - 1] # noqa: black conflict
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return out
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def _verify_h(signed_string, signature, pubkey):
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signer = PKCS1_v1_5.new(pubkey)
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digest = SHA256.new()
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digest.update(signed_string.encode("utf-8"))
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return signer.verify(digest, signature)
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def _body_digest() -> str:
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h = hashlib.new("sha256")
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h.update(request.data)
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return "SHA-256=" + base64.b64encode(h.digest()).decode("utf-8")
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def verify_request(actor_service) -> bool:
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hsig = _parse_sig_header(request.headers.get("Signature"))
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if not hsig:
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logger.debug("no signature in header")
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return False
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logger.debug(f"hsig={hsig}")
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signed_string = _build_signed_string(
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hsig["headers"], request.method, request.path, request.headers, _body_digest()
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)
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_, rk = actor_service.get_public_key(hsig["keyId"])
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return _verify_h(signed_string, base64.b64decode(hsig["signature"]), rk)
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class HTTPSigAuth(AuthBase):
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def __init__(self, keyid, privkey):
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self.keyid = keyid
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self.privkey = privkey
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def __call__(self, r):
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logger.info(f"keyid={self.keyid}")
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host = urlparse(r.url).netloc
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bh = hashlib.new("sha256")
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bh.update(r.body.encode("utf-8"))
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bodydigest = "SHA-256=" + base64.b64encode(bh.digest()).decode("utf-8")
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date = datetime.utcnow().strftime("%a, %d %b %Y %H:%M:%S GMT")
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r.headers.update({"Digest": bodydigest, "Date": date})
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r.headers.update({"Host": host})
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sigheaders = "(request-target) user-agent host date digest content-type"
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to_be_signed = _build_signed_string(
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sigheaders, r.method, r.path_url, r.headers, bodydigest
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)
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signer = PKCS1_v1_5.new(self.privkey)
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digest = SHA256.new()
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digest.update(to_be_signed.encode("utf-8"))
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sig = base64.b64encode(signer.sign(digest))
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sig = sig.decode("utf-8")
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headers = {
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"Signature": f'keyId="{self.keyid}",algorithm="rsa-sha256",headers="{sigheaders}",signature="{sig}"'
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}
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logger.info(f"signed request headers={headers}")
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r.headers.update(headers)
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return r
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