Squash Odysseus development history

companion/pairing.py

@@ -0,0 +1,227 @@
+"""Shared pairing helpers for the companion bridge.
+
+Token minting + LAN discovery + QR rendering, kept here as small, importable
+units so the route layer stays thin and the logic is directly testable.
+"""
+
+from __future__ import annotations
+
+import ipaddress
+import json
+import os
+import re
+import secrets
+import socket
+import uuid
+from urllib.parse import urlsplit
+
+import bcrypt
+
+from src.constants import AUTH_FILE
+
+PAIRING_VERSION = 1
+COMPANION_SCOPE = "chat"
+
+
+_COMPANION_IPV4_NETWORKS = tuple(
+    ipaddress.ip_network(cidr)
+    for cidr in (
+        "10.0.0.0/8",
+        "100.64.0.0/10",
+        "127.0.0.0/8",
+        "169.254.0.0/16",
+        "172.16.0.0/12",
+        "192.168.0.0/16",
+    )
+)
+_DNS_LABEL_RE = re.compile(r"[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?\Z")
+
+
+def _valid_companion_client_host(host: str) -> bool:
+    """Match the host forms supported by the current v1 Expo client."""
+    if not host or len(host) > 253 or not host.isascii() or "%" in host:
+        return False
+
+    try:
+        address = ipaddress.ip_address(host)
+    except ValueError:
+        labels = host.split(".")
+        if any(not _DNS_LABEL_RE.fullmatch(label) for label in labels):
+            return False
+        if any(label.startswith("xn--") for label in labels):
+            return False
+        # WHATWG URL parsers treat a decimal or ``0x`` single-label hostname
+        # as an IPv4 number even though Python's strict ``ipaddress`` parser
+        # rejects that spelling.  The v1 client interpolates this host back
+        # into a URL, so accepting e.g. ``134744072`` would make the phone send
+        # its bearer token to public 8.8.8.8.  Keep DNS labels unambiguous.
+        if len(labels) == 1 and (
+            labels[0].isdigit()
+            or re.fullmatch(r"0x[0-9a-f]*", labels[0]) is not None
+        ):
+            return False
+        return len(labels) == 1 or (len(labels) >= 2 and labels[-1] == "local")
+
+    return isinstance(address, ipaddress.IPv4Address) and any(
+        address in network for network in _COMPANION_IPV4_NETWORKS
+    )
+
+
+def parse_companion_base_url(value: str) -> tuple[str, int]:
+    """Validate a v1 companion address and return its legacy (host, port).
+
+    The deployed client understands only HTTP plus a LAN-style host and port.
+    Reject anything outside that exact contract instead of advertising a URL
+    the client would reject, downgrade, or interpret differently.
+    """
+    if not isinstance(value, str) or not value:
+        raise ValueError("COMPANION_BASE_URL must be a canonical HTTP LAN origin")
+    if not value.isascii():
+        raise ValueError("COMPANION_BASE_URL must contain only ASCII characters")
+    if any(
+        ord(char) <= 32 or ord(char) == 127 or char in {"\\", "%"}
+        for char in value
+    ):
+        raise ValueError(
+            "COMPANION_BASE_URL contains a forbidden character"
+        )
+
+    try:
+        parsed = urlsplit(value)
+        port = parsed.port
+    except ValueError as exc:
+        raise ValueError("COMPANION_BASE_URL must be a valid HTTP LAN origin") from exc
+
+    host = parsed.hostname
+    if parsed.scheme.lower() != "http" or not parsed.netloc or not host:
+        raise ValueError("COMPANION_BASE_URL must be a canonical HTTP LAN origin")
+    if parsed.username is not None or parsed.password is not None:
+        raise ValueError("COMPANION_BASE_URL must not contain credentials")
+    if parsed.path or parsed.query or parsed.fragment:
+        raise ValueError("COMPANION_BASE_URL must not contain a path, query, or fragment")
+    if port is not None and not 1 <= port <= 65535:
+        raise ValueError("COMPANION_BASE_URL port must be between 1 and 65535")
+    if not _valid_companion_client_host(host):
+        raise ValueError("COMPANION_BASE_URL host is not supported by companion v1")
+
+    netloc = f"{host}:{port}" if port is not None else host
+    origin = f"http://{netloc}"
+    if value != origin:
+        raise ValueError("COMPANION_BASE_URL must be a canonical HTTP LAN origin")
+    return host, port or 80
+
+
+def configured_companion_origin() -> tuple[str, int] | None:
+    """Return the validated operator-configured v1 address, if any."""
+    value = os.environ.get("COMPANION_BASE_URL")
+    if value is None or value == "":
+        return None
+    return parse_companion_base_url(value)
+
+
+def default_port() -> int:
+    """Best guess at the port the server is reachable on. Callers that know the
+    real request port should pass it explicitly."""
+    try:
+        return int(os.environ.get("APP_PORT", "7000"))
+    except ValueError:
+        return 7000
+
+
+def lan_ip_candidates() -> list[str]:
+    """Likely LAN IPv4 addresses for this host, best candidate first.
+
+    The UDP-connect trick reveals the egress interface the OS would use to reach
+    the default gateway -- i.e. the address a phone on the same Wi-Fi should
+    target. No packets are actually sent. Loopback is dropped.
+    """
+    candidates: list[str] = []
+
+    def _add(ip):
+        if ip and ip not in candidates and not ip.startswith("127."):
+            candidates.append(ip)
+
+    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    try:
+        s.connect(("8.8.8.8", 80))
+        _add(s.getsockname()[0])
+    except OSError:
+        pass
+    finally:
+        s.close()
+
+    try:
+        for info in socket.getaddrinfo(socket.gethostname(), None, socket.AF_INET):
+            _add(info[4][0])
+    except OSError:
+        pass
+
+    return candidates
+
+
+def find_admin_user() -> str | None:
+    """Resolve an admin username from data/auth.json (schema uses is_admin),
+    falling back to the first user."""
+    auth_path = AUTH_FILE
+    try:
+        with open(auth_path, "r", encoding="utf-8") as f:
+            data = json.load(f)
+    except (OSError, json.JSONDecodeError):
+        return None
+    if not isinstance(data, dict):
+        return None
+    users = data.get("users") or {}
+    if not isinstance(users, dict):
+        return None
+    for uname, udata in users.items():
+        if isinstance(udata, dict) and udata.get("is_admin") is True:
+            return uname
+    return next(iter(users), None)
+
+
+def mint_token(owner: str, name: str = "companion") -> tuple[str, str]:
+    """Create a chat-scoped API token row and return (token_id, raw_token).
+
+    The raw token is returned ONCE -- only its bcrypt hash + an 8-char prefix
+    are persisted. Mirrors routes/api_token_routes.py so cookie- and
+    companion-minted tokens are indistinguishable to the auth middleware.
+    """
+    from core.database import get_db_session, ApiToken
+
+    raw_token = "ody_" + secrets.token_urlsafe(32)
+    token_hash = bcrypt.hashpw(raw_token.encode(), bcrypt.gensalt()).decode()
+    token_id = str(uuid.uuid4())[:8]
+
+    with get_db_session() as db:
+        db.add(ApiToken(
+            id=token_id,
+            owner=owner,
+            name=name,
+            token_hash=token_hash,
+            token_prefix=raw_token[:8],
+            scopes=COMPANION_SCOPE,
+            is_active=True,
+        ))
+    return token_id, raw_token
+
+
+def pairing_payload(host: str, port: int, token: str) -> dict:
+    """The exact JSON a client scans / accepts. Keep keys stable."""
+    return {"v": PAIRING_VERSION, "host": host, "port": port, "token": token}
+
+
+def pairing_qr_png_data_uri(payload: dict) -> str | None:
+    """Render the pairing payload as a QR `data:` URI for an <img>. Returns None
+    if the optional qrcode dep is unavailable."""
+    try:
+        import base64
+        import io
+
+        import qrcode
+
+        img = qrcode.make(json.dumps(payload, separators=(",", ":")))
+        buf = io.BytesIO()
+        img.save(buf, format="PNG")
+        return "data:image/png;base64," + base64.b64encode(buf.getvalue()).decode()
+    except Exception:
+        return None