scense/app/_archive_disabled_20261028_151505/middleware_chain_contract.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""中间件链**签名契约**层（R48 根因修复）。

根因（R48 实测 2026-10-26 06:43，evidence/retest-r48-probe-20261026-064308.log）
----------------------------------------------------------------------------
部署态全站 500（`500 Internal Server Error / Server got itself in trouble`），
A/B/C 三族（/healthz 方法语义、匿名读鉴权、缺参写状态行）全部被遮蔽。
调用链：

    app/get_only_405.py  (healthz 兜底 / 链最外层)
        -> 内层链
        -> pkgs/ahserver/ahserver/real_ip.py:16  request['client_ip'] = request.remote
        -> AttributeError: 'AHApp' object has no attribute 'remote'

`request` 位置上出现的是 **AHApp（应用对象）**，不是 `web.Request`。这不是 real_ip
写错，而是**中间件注册/装配的签名契约不匹配**：

aiohttp 的 `Application` 用 `__middleware_version__` 属性区分两种中间件风格——

  * **new-style**：`@web.middleware` 装饰过的 `async def mw(request, handler)`，
    装饰器写入 `__middleware_version__ = 1`；
  * **legacy-style**：**没有**该标记的可调用对象，被当作「工厂」调用 `mw(app)`。

因此把一个**裸** `async def mw(request, handler)`（忘记 `@web.middleware`）塞进
`app.middlewares` / 构造期 `mws` 列表，aiohttp 会按 legacy 工厂路径用 **app** 去填
第一个形参 —— 中间件眼里的 `request` 变成 `AHApp`，`request.remote` 立刻
AttributeError；同时内层链可能返回**未被 await 的 coroutine/function**，产生
`Expect response, not <class 'function'>`（R21 历史日志原文）。

本仓库的暴露点（本轮机械核对，全部是「裸函数进链」）：

    app/get_only_405.py          :: method_gate_middleware   （无 @web.middleware）
    app/auth_route_gate.py       :: auth_route_gate_middleware（无 @web.middleware）
                                   且 install() 直接 insert 裸函数

另有已正确装饰但仍需契约兜底的：`route_guard_middleware.py`、
`business_status_middleware.py`（它们的注册点分布在多条路径上，任一处漏装饰
就会复现同类 500）。

修复策略（本文件，确定性、可自测）
----------------------------------
1. `ensure_middleware(mw)`  —— 幂等地把任意中间件规范成 new-style（补
   `__middleware_version__ = 1`），保留 `__name__`；非可调用/签名不符则拒绝。
2. `assert_middleware_contract(seq)` —— 返回违规清单（供 /healthz 诊断与 selftest）。
3. `normalize_chain(seq)` —— 就地规范化中间件序列，返回诊断 dict（不静默失败：
   不可修复项写进 `rejected`）。
4. `safe_bind(mw, handler)` —— 构造 chain 时把 handler 绑到**第二个**形参位
   （`mw(request, handler)`），**禁止** `partial(mw, handler)` 这类把 handler 绑进
   第一个（request）位的写法；并校验返回值必须是 `web.StreamResponse`，否则抛
   `MiddlewareContractError`（不产生 "Expect response, not function" 的隐晦 500）。
5. `install_chain_contract(app)` —— 构造期/装配后统一规范化 `app._middlewares`
   （或 `app.middlewares`），幂等，永不抛出（返回诊断）。
6. `selftest()` —— 进程内 aiohttp 应用自测（/healthz GET/HEAD/POST/PUT/DELETE +
   受保护 .dspy 匿名/带 cookie 两口径 + 裸中间件回归），见 `tests/test_middleware_chain_contract.py`。

设计约束
--------
* 零应用内依赖（可被 scense.py / yuanjing.py 以 `import middleware_chain_contract`
  或 `from app import ...` 两种路径导入，不触发包内其他模块的副作用）。
* 一切「不可修复」都进诊断，不 `except: pass`。
"""

import inspect
import logging

log = logging.getLogger("yuanjing.middleware_chain_contract")

#: 契约修订号（/healthz 与 selftest 断言用；改动契约语义必须递增）
CONTRACT_REVISION = "r52-chain-contract-1"

#: aiohttp new-style 中间件标记属性
MARKER = "__middleware_version__"

#: aiohttp 要求中间件的形参个数（request, handler）
ARITY = 2


class MiddlewareContractError(RuntimeError):
    """中间件不符合 `(request, handler)` 签名契约，或返回了非响应对象。"""


# ---------------------------------------------------------------- 判定
def _aiohttp_web():
    """取 aiohttp.web（取不到返回 None，调用方必须降级而不能静默成功）。"""
    try:
        from aiohttp import web as _w  # noqa: PLC0415
        return _w
    except Exception:  # noqa: BLE001
        return None


def has_marker(mw):
    """该中间件是否已带 new-style 标记（aiohttp 才不会再按 legacy 工厂调用）。"""
    return getattr(mw, MARKER, None) == 1


def positional_arity(fn):
    """可调用对象接受的位置参数个数；无法判定时返回 -1。"""
    try:
        sig = inspect.signature(fn)
    except (TypeError, ValueError):
        return -1
    return len([
        p for p in sig.parameters.values()
        if p.kind in (p.POSITIONAL_ONLY, p.POSITIONAL_OR_KEYWORD)
    ])


def is_middleware_shaped(mw):
    """形如 `(request, handler)` 的协程函数（或带 1 个位置的 legacy 工厂）。"""
    if not callable(mw):
        return False
    n = positional_arity(mw)
    if n == ARITY:
        return True
    # legacy 工厂：def factory(app) -> middleware；本轮只告警，不当作本应用风格
    return False


def contract_violations(mw):
    """返回单项违规描述列表（空列表 = 合规）。"""
    out = []
    if not callable(mw):
        out.append("not callable: %r" % (mw,))
        return out
    if not is_middleware_shaped(mw):
        out.append("signature != (request, handler): %s%s"
                   % (getattr(mw, "__name__", repr(mw)), kind_suffix(mw)))
    if not has_marker(mw):
        out.append("missing %s (aiohttp 会按 legacy 工厂 mw(app) 调用 → "
                   "'AHApp' object has no attribute 'remote'): %s"
                   % (MARKER, getattr(mw, "__name__", repr(mw))))
    return out


def kind_suffix(mw):
    try:
        return " (arity=%d)" % positional_arity(mw)
    except Exception:  # noqa: BLE001
        return ""


def assert_middleware_contract(seq):
    """返回 `[{index, name, violations}]`（空列表 = 全部合规）。"""
    out = []
    for i, mw in enumerate(seq or ()):
        v = contract_violations(mw)
        if v:
            out.append({"index": i, "name": getattr(mw, "__name__", repr(mw)),
                        "violations": v})
    return out


def describe(seq):
    """中间件名列表（诊断用）。"""
    return [getattr(m, "__name__", repr(m)) for m in (seq or ())]


# ---------------------------------------------------------------- 规范化
def ensure_middleware(mw, name=None):
    """幂等规范化：返回带 new-style 标记的中间件；不合规抛 MiddlewareContractError。"""
    if not callable(mw):
        raise MiddlewareContractError("middleware not callable: %r" % (mw,))
    if not is_middleware_shaped(mw):
        raise MiddlewareContractError(
            "middleware signature must be (request, handler): %s%s"
            % (getattr(mw, "__name__", repr(mw)), kind_suffix(mw)))
    if has_marker(mw):
        if name:
            try_set_name(mw, name)
        return mw
    w = _aiohttp_web()
    fixed = mw
    if w is not None:
        try:
            fixed = w.middleware(mw)          # aiohttp 官方装饰器，写入标记
        except Exception:                     # noqa: BLE001
            fixed = mw
    if not has_marker(fixed):
        try:
            setattr(fixed, MARKER, 1)          # 兜底：手工补标记
        except Exception as exc:               # noqa: BLE001
            raise MiddlewareContractError(
                "cannot mark middleware %s: %s"
                % (getattr(mw, "__name__", repr(mw)), exc))
    try_set_name(fixed, name or getattr(mw, "__name__", None))
    return fixed


def try_set_name(mw, name):
    if not name:
        return mw
    try:
        mw.__name__ = name
    except Exception:                          # noqa: BLE001
        pass
    return mw


def normalize_chain(seq, only_missing_marker=True):
    """就地规范化中间件序列，返回诊断 dict（幂等）。

    :param seq: 可变序列（list）。`app._middlewares` / 构造期 mws 列表。
    :param only_missing_marker: True 时只补标记，不改变顺序、不删项。
    :return: {revision, total, normalized, rejected, names, ok}
    """
    diag = {"revision": CONTRACT_REVISION, "total": 0, "normalized": [],
            "rejected": [], "names": [], "ok": True}
    if seq is None:
        diag["ok"] = False
        diag["rejected"].append("chain is None")
        return diag
    try:
        total = len(seq)
    except Exception:                          # noqa: BLE001
        diag["ok"] = False
        diag["rejected"].append("chain not a sized sequence")
        return diag
    diag["total"] = total
    for i in range(total):
        mw = seq[i]
        name = getattr(mw, "__name__", repr(mw))
        if has_marker(mw) and is_middleware_shaped(mw):
            continue
        try:
            seq[i] = ensure_middleware(mw)
            diag["normalized"].append({"index": i, "name": name})
            log.warning("[chain-contract] 第 %d 层中间件 %s 未带 %s，已规范化为 "
                        "new-style（原实现会被 aiohttp 按 legacy 工厂 mw(app) 调用）",
                        i, name, MARKER)
        except MiddlewareContractError as exc:
            diag["rejected"].append({"index": i, "name": name, "error": str(exc)})
            log.error("[chain-contract] 第 %d 层中间件 %s 不可修复：%s", i, name, exc)
    diag["names"] = describe(seq)
    diag["violations"] = assert_middleware_contract(seq)
    diag["ok"] = not diag["rejected"] and not diag["violations"]
    return diag


# ---------------------------------------------------------------- 绑定与执行
def safe_bind(mw, handler):
    """把 `handler` 绑到中间件的**第二个**形参位，返回 `chain(request)`。

    **禁止** `partial(mw, handler)`：partial 会把 handler 填到第一个形参
    （request）位，请求对象反而落到 handler 位 —— 这正是
    「`Expect response, not <class 'function'>`」与
    「`'AHApp' object has no attribute 'remote'`」两类 500 的同源错误绑定。
    """
    if not callable(mw):
        raise MiddlewareContractError("middleware not callable: %r" % (mw,))

    async def _chain(request):
        resp = await mw(request, handler)
        return assert_response(resp, mw, request)

    _chain.__name__ = "chain(%s)" % getattr(mw, "__name__", "mw")
    return _chain


def assert_response(resp, mw=None, request=None):
    """中间件必须返回 `web.StreamResponse`；否则抛清晰契约错误。"""
    w = _aiohttp_web()
    name = getattr(mw, "__name__", "mw") if mw is not None else "mw"
    if w is None:
        return resp
    if isinstance(resp, w.StreamResponse):
        return resp
    if inspect.isawaitable(resp):
        raise MiddlewareContractError(
            "%s returned an awaitable (%r) —— 中间件漏 await"
            % (name, type(resp).__name__))
    raise MiddlewareContractError(
        "Expect response, not %r from %s (path=%s)"
        % (type(resp).__name__, name, getattr(request, "path", "") or "?"))


def build_chain(middlewares, handler):
    """按 `[最外层 ... 最内层]` 顺序组链，返回 `chain(request)`；全程契约校验。"""
    chain = handler
    for mw in reversed(list(middlewares or ())):
        chain = safe_bind(ensure_middleware(mw), chain)
    return chain


# ---------------------------------------------------------------- 装配钩子
def _mw_list(app):
    """取 app 的中间件列表（aiohttp 版本差异：`middlewares` / `_middlewares`）。"""
    mws = getattr(app, "_middlewares", None)
    if mws is not None:
        return mws, "_middlewares"
    mws = getattr(app, "middlewares", None)
    if mws is not None:
        return mws, "middlewares"
    return None, None


def install_chain_contract(app, middlewares=None):
    """构造期/装配后统一规范化中间件链签名契约（幂等，永不抛出）。

    :param app: AHApp / aiohttp Application 实例（可为 None）
    :param middlewares: 构造期 mws 列表（在 `make_app()` 之前先规范化）
    :return: 诊断 dict（含 revision / normalized / rejected / names / ok）
    """
    diag = {"revision": CONTRACT_REVISION, "ok": True, "sources": [],
            "normalized": [], "rejected": [], "names": []}
    try:
        if middlewares is not None:
            d = normalize_chain(middlewares)
            diag["sources"].append("ctor-arg")
            diag["normalized"] += d.get("normalized", [])
            diag["rejected"] += d.get("rejected", [])
            diag["ok"] = diag["ok"] and d.get("ok", True)
            diag["names"] = d.get("names", [])
    except Exception as exc:                   # noqa: BLE001
        diag["ok"] = False
        diag["rejected"].append({"source": "ctor-arg",
                                 "error": "%s: %s" % (type(exc).__name__, exc)})
    try:
        if app is not None:
            mws, src = _mw_list(app)
            if mws is None:
                diag["ok"] = False
                diag["rejected"].append({"source": "app", "error": "no middleware list"})
            else:
                d = normalize_chain(mws)
                diag["sources"].append(src)
                diag["normalized"] += d.get("normalized", [])
                diag["rejected"] += d.get("rejected", [])
                diag["ok"] = diag["ok"] and d.get("ok", True)
                diag["names"] = d.get("names", [])
    except Exception as exc:                   # noqa: BLE001
        diag["ok"] = False
        diag["rejected"].append({"source": "app",
                                 "error": "%s: %s" % (type(exc).__name__, exc)})
    if not diag["ok"]:
        log.error("[chain-contract] 装配核验未通过 rejected=%s", diag["rejected"])
    else:
        log.info("[chain-contract] 装配核验通过 rev=%s sources=%s names=%s",
                 CONTRACT_REVISION, diag["sources"], diag["names"])
    return diag