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"""
A node in memory, at the level of the MNP messages the CLI sends.
It does the real cryptography — chunks encrypted under the per-chunk key,
uploads unsealed under the group key, acks sealed back — and keeps the rules
that shape the client: a lease before any chunk, chunks of an upload in order,
the position an interrupted upload resumes from, no overwrite. Not a model of
the node's code: a node the CLI must work against.
"""
import asyncio
import base64
import hashlib
import math
import secrets
from cryptography.hazmat.primitives.asymmetric.ed25519 import (
Ed25519PrivateKey,
Ed25519PublicKey,
)
from cryptography.hazmat.primitives.asymmetric.x25519 import X25519PrivateKey
from fake_hub import USER_ID
from meshbay_cli.client.keys import Identity
from meshbay_cli.client.session import GroupSession, NodeRefusal
from meshbay_common.device import (
device_add_transcript,
device_code_hash,
device_revoke_transcript,
)
from meshbay_common.groupbox import PURPOSE_INDEX, PURPOSE_UPLOAD, seal, unseal
from meshbay_common.protocol import UPLOAD_PROBE_INDEX, file_upload_ack_wire
from meshbay_common.webcrypto import chunk_key_aes, encrypt_chunk_aes
GROUP_ID = "g1"
NODE_PK = base64.b64encode(b"\x05" * 32).decode()
CHUNK = 1024 * 1024
class FakeNode:
def __init__(self, *, writable: bool = True):
self.gek = secrets.token_bytes(32)
self.roots = [{"name": "share", "available": True, "writable": writable}]
self.dirs = {"share"}
self.files: dict[str, dict] = {} # id → entry, with "data"
self.leases: dict[str, str] = {} # tr → state
self.queue_first = 0 # leases to answer "queued" before granting
self.uploads: dict[tuple, dict] = {} # (dir, name) → {"next", "data"}
self.fail_chunk: tuple[str, int] | None = None # (file_id, index) → refused
self.refuse_upload_code = ""
self.chunk_requests = 0
self.chunk_delay = 0.0
# This machine's key here, the account's other devices, and the requests
# waiting for an approval — each `{pk_ed25519, pk_x25519, code_hash}`.
self.identity = Identity(Ed25519PrivateKey.generate(), X25519PrivateKey.generate())
self.nonce = secrets.token_bytes(32)
self.devices = [{"pk_ed25519": self.identity.pk_ed, "pk_x25519": self.identity.pk_x,
"label": "", "pinned_at": "2026-10-01T10:00:00+00:00",
"pinned_via": "code"}]
self.requests: list[dict] = []
def add(self, path: str, name: str, data: bytes) -> dict:
fid = hashlib.blake2b(data + path.encode() + name.encode(), digest_size=32).hexdigest()
entry = {"id": fid, "name": name, "path": path, "size": len(data),
"type": "document", "added_at": 1_700_000_000, "data": data}
self.files[fid] = entry
parts = path.split("/")
for i in range(1, len(parts) + 1):
self.dirs.add("/".join(parts[:i]))
return entry
def session(self) -> GroupSession:
return GroupSession(None, FakeChannel(self), GROUP_ID, "node-1", NODE_PK, self.gek,
{}, self.identity, self.nonce)
def request_device(self, code: str) -> Identity:
"""Another machine files a request with `code`, as it would before its proof."""
other = Identity(Ed25519PrivateKey.generate(), X25519PrivateKey.generate())
self.requests.append({"pk_ed25519": other.pk_ed, "pk_x25519": other.pk_x,
"created_at": "2026-10-14T10:00:00+00:00",
"code_hash": device_code_hash(code.replace("-", ""),
other.pk_ed, other.pk_x)})
return other
def stored(self, path: str) -> bytes | None:
parent, _, name = path.rpartition("/")
for e in self.files.values():
if e["path"] == parent and e["name"] == name:
return e["data"]
return None
class FakeChannel:
def __init__(self, node: FakeNode):
self.node = node
self.closed = asyncio.Event()
self._push: dict[str, list] = {}
def on_push(self, t, h):
self._push.setdefault(t, []).append(h)
def off_push(self, t, h):
if h in self._push.get(t, []):
self._push[t].remove(h)
def _emit(self, msg):
for h in list(self._push.get(msg["type"], [])):
h(msg)
async def request(self, msg: dict, *expect: str, timeout: float = 60) -> dict:
await asyncio.sleep(self.node.chunk_delay if msg["type"] == "file_req" else 0)
reply = getattr(self, "_" + msg["type"])(msg)
if reply.get("type") == "error":
raise NodeRefusal(reply["detail"], reply.get("code", ""))
return reply
# ── Messages ─────────────────────────────────────────────────────────────
def _index_sync(self, msg):
n = self.node
payload = {"version": 1, "roots": n.roots, "dirs": sorted(n.dirs),
"entries": [{k: v for k, v in e.items() if k != "data"}
for e in n.files.values()]}
return {"type": "index_sync", "group_id": GROUP_ID,
**seal(n.gek, PURPOSE_INDEX, "index_sync", GROUP_ID, payload)}
def _transfer_open(self, msg):
tr = msg["tr"]
if self.node.queue_first:
self.node.queue_first -= 1
self.node.leases[tr] = "queued"
asyncio.get_running_loop().call_later(0.01, self._grant, tr)
return {"type": "transfer_state", "tr": tr, "state": "queued", "ahead": 1}
self.node.leases[tr] = "granted"
return {"type": "transfer_state", "tr": tr, "state": "granted"}
def _grant(self, tr):
self.node.leases[tr] = "granted"
self._emit({"type": "transfer_state", "tr": tr, "state": "granted"})
def _transfer_close(self, msg):
self.node.leases.pop(msg["tr"], None)
return {"type": "transfer_state", "tr": msg["tr"], "state": "closed"}
def _file_req(self, msg):
n = self.node
n.chunk_requests += 1
if n.leases.get(msg.get("tr")) != "granted":
return {"type": "error", "detail": "no lease", "code": "lease_not_granted"}
if n.fail_chunk == (msg["file_id"], msg["chunk_index"]):
return {"type": "error", "detail": "The drive stopped answering"}
entry = n.files[msg["file_id"]]
i = msg["chunk_index"]
data = entry["data"][i * CHUNK:(i + 1) * CHUNK]
nonce, ct = encrypt_chunk_aes(chunk_key_aes(n.gek, bytes.fromhex(entry["id"]), i), data)
return {"type": "file_chunk", "chunk_index": i, "nonce": nonce, "ct": ct}
def _dir_create(self, msg):
root = self.node.roots[0]
if not root["writable"]:
return {"type": "error", "detail": "read-only", "code": "root_read_only"}
path = f"{msg['dir']}/{msg['name']}"
self.node.dirs.add(path)
return {"type": "dir_create_ack", "dir": path}
def _file_upload(self, msg):
n = self.node
if n.leases.get(msg.get("tr")) != "granted":
return {"type": "error", "detail": "no lease", "code": "lease_not_granted"}
p = unseal(n.gek, PURPOSE_UPLOAD, "file_upload", GROUP_ID, msg)
name, folder, i = p["filename"], p["dir"], msg["chunk_index"]
if n.refuse_upload_code:
return {"type": "error", "detail": "refused", "code": n.refuse_upload_code}
key = (folder, name)
state = n.uploads.get(key)
stored = name
while n.stored(f"{folder}/{stored}") is not None:
stem, dot, ext = name.partition(".")
stored = f"{stem} (1){dot}{ext}"
if i == UPLOAD_PROBE_INDEX:
return file_upload_ack_wire(n.gek, GROUP_ID, upload_id=msg["upload_id"],
chunk_index=i, filename=name, stored_as="",
dir=folder, resume_from=state["next"] if state else 0)
if state is None:
state = n.uploads[key] = {"next": 0, "data": b""}
if i != state["next"]:
return {"type": "error", "detail": "Out of order", "code": "bad_chunk_index"}
state["data"] += p["data"]
state["next"] += 1
if state["next"] >= msg["total_chunks"]:
del n.uploads[key]
n.add(folder, stored, state["data"])
return file_upload_ack_wire(n.gek, GROUP_ID, upload_id=msg["upload_id"],
chunk_index=i, filename=name, stored_as=stored,
dir=folder)
# ── Devices ──────────────────────────────────────────────────────────────
def _device_list(self, msg):
n = self.node
return {"type": "device_list_result", "pending": len(n.requests),
"devices": [{**d, "is_this_one": d["pk_ed25519"] == n.identity.pk_ed}
for d in n.devices]}
def _device_lookup(self, msg):
return {"type": "device_lookup_result", "requests": list(self.node.requests)}
def _device_add(self, msg):
n = self.node
transcript = device_add_transcript(
node_pk_b64=NODE_PK, user_id=USER_ID, pk_ed25519_b64=msg["pk_ed25519"],
pk_x25519_b64=msg["pk_x25519"], nonce_node=n.nonce, ts=msg["ts"])
if not _signed_by_a_device(n, transcript, msg["sig"]):
return {"type": "error", "detail": "Not signed by a device already paired here"}
req = next((r for r in n.requests if r["code_hash"] == msg["code_hash"]
and r["pk_ed25519"] == msg["pk_ed25519"]), None)
if req is None:
return {"type": "error", "detail": "No pending request"}
n.requests.remove(req)
n.devices.append({"pk_ed25519": req["pk_ed25519"], "pk_x25519": req["pk_x25519"],
"label": "", "pinned_at": "2026-10-14T10:01:00+00:00",
"pinned_via": "device"})
return {"type": "device_add_ack", "pk_ed25519": req["pk_ed25519"]}
def _device_revoke(self, msg):
n = self.node
transcript = device_revoke_transcript(
node_pk_b64=NODE_PK, user_id=USER_ID, pk_ed25519_b64=msg["pk_ed25519"],
nonce_node=n.nonce, ts=msg["ts"])
if not _signed_by_a_device(n, transcript, msg["sig"]):
return {"type": "error", "detail": "Not signed by a device already paired here"}
if len(n.devices) <= 1:
return {"type": "error", "detail": "This is your only device here"}
n.devices = [d for d in n.devices if d["pk_ed25519"] != msg["pk_ed25519"]]
return {"type": "device_add_ack", "revoked": msg["pk_ed25519"]}
def _signed_by_a_device(node: FakeNode, transcript: bytes, sig: str) -> bool:
for d in node.devices:
try:
Ed25519PublicKey.from_public_bytes(base64.b64decode(d["pk_ed25519"])).verify(
base64.b64decode(sig), transcript)
return True
except Exception:
continue
return False
def chunks_of(size: int, chunk: int) -> int:
return max(1, math.ceil(size / chunk))
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