feat: v6.7.0 — SSO/SAML + OIDC entreprise (SP SAML signé + OIDC PKCE, auto-provisioning, groupes IdP → rôles workspace, SSO only, onglet Settings « SSO / Enterprise », API /api/v2/sso/*, help, migration 23, docs + OpenAPI 439 chemins) · 802 tests verts

app/auth/providers/oidc_provider.py

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+"""OIDC provider — authorization code flow with PKCE (v6.7.0).
+
+Discovery (``.well-known/openid-configuration``) is cached for an hour, the
+ID token signature is verified against the issuer JWKS via authlib's JOSE
+implementation, and ``iss`` / ``aud`` / ``exp`` / ``nonce`` are checked here
+explicitly so the rules are visible and unit-testable.
+"""
+from __future__ import annotations
+
+import base64
+import hashlib
+import json
+import logging
+import secrets
+import time
+import warnings
+
+import httpx
+
+logger = logging.getLogger(__name__)
+
+#: Default attribute mapping (design doc §3.2) — OIDC claim names.
+DEFAULT_OIDC_MAPPING: dict[str, str] = {
+    "login": "sub",
+    "email": "email",
+    "full_name": "name",
+    "avatar_url": "picture",
+    "groups": "groups",
+}
+
+_DISCOVERY_TTL = 3600.0
+_discovery_cache: dict[str, tuple[float, dict]] = {}
+
+
+class OIDCError(Exception):
+    """OIDC processing failure — ``message`` is user-facing."""
+
+
+def pkce_pair() -> tuple[str, str]:
+    """Return ``(code_verifier, code_challenge)`` for the S256 method."""
+    verifier = secrets.token_urlsafe(64)
+    digest = hashlib.sha256(verifier.encode("ascii")).digest()
+    challenge = base64.urlsafe_b64encode(digest).rstrip(b"=").decode("ascii")
+    return verifier, challenge
+
+
+def _b64url(data: bytes) -> str:
+    return base64.urlsafe_b64encode(data).rstrip(b"=").decode("ascii")
+
+
+def _b64url_decode(data: str) -> bytes:
+    return base64.urlsafe_b64decode(data + "=" * (-len(data) % 4))
+
+
+async def discover(issuer_url: str) -> dict:
+    """Fetch (and cache) the issuer's OIDC discovery document."""
+    issuer = issuer_url.rstrip("/")
+    url = f"{issuer}/.well-known/openid-configuration"
+    now = time.time()
+    hit = _discovery_cache.get(issuer)
+    if hit and now - hit[0] < _DISCOVERY_TTL:
+        return hit[1]
+    try:
+        async with httpx.AsyncClient(timeout=15) as client:
+            r = await client.get(url)
+            r.raise_for_status()
+            doc = r.json()
+    except Exception as err:
+        raise OIDCError(f"OIDC discovery failed ({url}): {err}") from err
+    if not doc.get("authorization_endpoint") or not doc.get("token_endpoint"):
+        raise OIDCError("OIDC discovery document is missing authorization/token endpoints")
+    _discovery_cache[issuer] = (now, doc)
+    return doc
+
+
+def build_authorize_url(
+    doc: dict,
+    *,
+    client_id: str,
+    redirect_uri: str,
+    scope: str,
+    state: str,
+    nonce: str,
+    code_challenge: str,
+) -> str:
+    from urllib.parse import urlencode
+
+    params = {
+        "client_id": client_id,
+        "redirect_uri": redirect_uri,
+        "response_type": "code",
+        "scope": scope or "openid profile email",
+        "state": state,
+        "nonce": nonce,
+        "code_challenge": code_challenge,
+        "code_challenge_method": "S256",
+    }
+    sep = "&" if "?" in doc["authorization_endpoint"] else "?"
+    return doc["authorization_endpoint"] + sep + urlencode(params)
+
+
+async def exchange_code(
+    doc: dict, *, client_id: str, client_secret: str, code: str, redirect_uri: str, code_verifier: str
+) -> dict:
+    """Exchange the authorization code for tokens (PKCE, confidential client)."""
+    data = {
+        "grant_type": "authorization_code",
+        "code": code,
+        "redirect_uri": redirect_uri,
+        "client_id": client_id,
+        "code_verifier": code_verifier,
+    }
+    auth = None
+    if client_secret:
+        auth = (client_id, client_secret)
+    try:
+        async with httpx.AsyncClient(timeout=15) as client:
+            r = await client.post(doc["token_endpoint"], data=data, auth=auth)
+    except Exception as err:
+        raise OIDCError(f"OIDC token request failed: {err}") from err
+    if r.status_code != 200:
+        raise OIDCError(f"OIDC token endpoint returned {r.status_code}: {r.text[:300]}")
+    try:
+        tokens = r.json()
+    except Exception as err:
+        raise OIDCError(f"OIDC token endpoint returned a non-JSON body: {err}") from err
+    if "error" in tokens:
+        raise OIDCError(f"OIDC error: {tokens.get('error')} {tokens.get('error_description', '')}".strip())
+    return tokens
+
+
+async def fetch_userinfo(doc: dict, access_token: str) -> dict:
+    """Best-effort userinfo fetch (groups often only live there)."""
+    endpoint = doc.get("userinfo_endpoint")
+    if not endpoint or not access_token:
+        return {}
+    try:
+        async with httpx.AsyncClient(timeout=15) as client:
+            r = await client.get(endpoint, headers={"Authorization": f"Bearer {access_token}"})
+        if r.status_code != 200:
+            return {}
+        data = r.json()
+        return data if isinstance(data, dict) else {}
+    except Exception as err:  # userinfo is optional enrichment
+        logger.debug("userinfo fetch failed: %s", err)
+        return {}
+
+
+def validate_id_token(
+    id_token: str, *, issuer: str, client_id: str, nonce: str, jwks: dict
+) -> dict:
+    """Verify the ID token signature and claims. Returns the claims dict."""
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore", DeprecationWarning)
+        from authlib.jose import JsonWebKey
+        from authlib.jose import jwt as jose_jwt
+
+    if isinstance(id_token, bytes):
+        # authlib's jose.jwt.encode() returns bytes; IdP token endpoints send
+        # str — accept both instead of crashing on ``bytes.count(".")``.
+        id_token = id_token.decode()
+    if not id_token or id_token.count(".") != 2:
+        raise OIDCError("Missing or malformed ID token")
+
+    try:
+        keyset = JsonWebKey.import_key_set(jwks)
+    except Exception as err:
+        raise OIDCError(f"Invalid issuer JWKS: {err}") from err
+
+    try:
+        # Pick the key matching the token header (kid) when several are offered.
+        header = json.loads(_b64url_decode(id_token.split(".")[0]))
+        kid = header.get("kid")
+        key = keyset.get_by_kid(kid) if kid and hasattr(keyset, "get_by_kid") else None
+        token_obj = jose_jwt.decode(id_token, key or keyset)
+    except Exception as err:
+        raise OIDCError(f"ID token signature verification failed: {err}") from err
+
+    claims = dict(token_obj)  # authlib's JWTClaims is a dict subclass
+    now = int(time.time())
+
+    if claims.get("iss") != issuer.rstrip("/") and claims.get("iss") != issuer:
+        raise OIDCError(f"ID token issuer mismatch: {claims.get('iss')!r}")
+    aud = claims.get("aud")
+    aud_list = aud if isinstance(aud, list) else [aud]
+    if client_id not in aud_list:
+        raise OIDCError("ID token audience does not include this client")
+    exp = claims.get("exp")
+    if not isinstance(exp, int) or exp < now:
+        raise OIDCError("ID token expired")
+    iat = claims.get("iat")
+    if isinstance(iat, int) and iat > now + 300:
+        raise OIDCError("ID token issued in the future")
+    if nonce and claims.get("nonce") != nonce:
+        raise OIDCError("ID token nonce mismatch")
+    if not claims.get("sub"):
+        raise OIDCError("ID token has no subject")
+    return claims
+
+
+def claims_to_identity(claims: dict, mapping: dict | None = None) -> dict:
+    """Map OIDC claims onto the shared ``{login, email, full_name, avatar_url, groups}`` shape."""
+    mapping = mapping or DEFAULT_OIDC_MAPPING
+    identity: dict = {"_raw": claims}
+    for field in ("login", "email", "full_name", "avatar_url"):
+        source = mapping.get(field) or field
+        value = claims.get(source, "")
+        if isinstance(value, list):
+            value = value[0] if value else ""
+        identity[field] = str(value or "").strip()
+    groups = claims.get(mapping.get("groups", "groups"), [])
+    if isinstance(groups, str):
+        groups = [groups]
+    identity["groups"] = [str(g) for g in groups if g]
+    if not identity["email"]:
+        identity["email"] = claims.get("email", "") or ""
+    if not identity["full_name"]:
+        identity["full_name"] = claims.get("name", "") or identity["email"]
+    return identity