OmniRoute/open-sse/utils/proxyFetch.ts

// @ts-nocheck
import "./setupPolyfill.ts";
import { AsyncLocalStorage } from "node:async_hooks";
import { fetch as undiciFetch } from "undici";
import {
  buildVercelRelayHeaders,
  createProxyDispatcher,
  getDefaultDispatcher,
  getRetryDispatcher,
  isRelayType,
  normalizeProxyUrl,
  proxyConfigToUrl,
  proxyUrlForLogs,
} from "./proxyDispatcher.ts";
import tlsClient from "./tlsClient.ts";
import { isProxyReachable } from "@/lib/proxyHealth";
import {
  isControlPlaneProxyDirectFallbackEnabled,
  isFeatureFlagEnabled,
} from "@/shared/utils/featureFlags";
import { findWorkingProxy } from "./proxyFallback.ts";

function isTlsFingerprintEnabled() {
  return process.env.ENABLE_TLS_FINGERPRINT === "true";
}

/** Per-request tracking of whether TLS fingerprint was used */
type TlsFingerprintStore = { used: boolean };
const tlsFingerprintContext = new AsyncLocalStorage<TlsFingerprintStore>();

type FetchWithDispatcherOptions = RequestInit & { dispatcher?: unknown };
type FetchWithDispatcher = (
  input: RequestInfo | URL,
  init?: FetchWithDispatcherOptions
) => Promise<Response>;

/**
 * Flatten a fetch error's `cause` chain (and any Happy-Eyeballs `AggregateError`
 * sub-errors) into a single diagnostic line: code/syscall/errno/address:port + a
 * truncated message. undici/native both reject with a bare `TypeError: fetch failed`
 * whose real reason hides in `.cause`; surfacing it is what makes dispatcher-failure
 * bursts (#4252) diagnosable. Never includes a stack trace (Rule #12). Pure + testable.
 */
export function describeFetchCause(err: unknown): string {
  const parts: string[] = [];
  const seen = new Set<unknown>();
  let cur: unknown = err;
  for (let depth = 0; cur && depth < 5 && !seen.has(cur); depth++) {
    seen.add(cur);
    const e = cur as Record<string, unknown>;
    const seg = [
      typeof e.name === "string" && e.name !== "Error" ? e.name : null,
      typeof e.message === "string" ? e.message.slice(0, 160) : null,
      e.code != null ? `code=${String(e.code)}` : null,
      e.syscall != null ? `syscall=${String(e.syscall)}` : null,
      e.errno != null ? `errno=${String(e.errno)}` : null,
      e.address != null
        ? `address=${String(e.address)}${e.port != null ? `:${String(e.port)}` : ""}`
        : null,
    ]
      .filter(Boolean)
      .join(" ");
    if (seg) parts.push(seg);
    if (Array.isArray(e.errors)) {
      for (const sub of (e.errors as unknown[]).slice(0, 4)) {
        const s = (sub ?? {}) as Record<string, unknown>;
        const subSeg = [
          s.code != null ? `code=${String(s.code)}` : null,
          s.syscall != null ? `syscall=${String(s.syscall)}` : null,
          s.address != null
            ? `address=${String(s.address)}${s.port != null ? `:${String(s.port)}` : ""}`
            : null,
        ]
          .filter(Boolean)
          .join(" ");
        if (subSeg) parts.push(`↳ ${subSeg}`);
        else if (typeof s.message === "string") parts.push(`↳ ${s.message.slice(0, 80)}`);
      }
    }
    cur = e.cause;
  }
  return parts.join(" | ") || String(err);
}

/** Injectable dependencies for testability (Approach B DI). */
export type ProxyFetchDeps = {
  undiciFetch?: FetchWithDispatcher;
  nativeFetch?: (input: RequestInfo | URL, init?: RequestInit) => Promise<Response>;
};

type PatchState = {
  originalFetch: typeof globalThis.fetch;
  proxyContext: AsyncLocalStorage<unknown>;
  isPatched: boolean;
};

const isCloud = typeof caches !== "undefined" && typeof caches === "object";
const PATCH_STATE_KEY = Symbol.for("omniroute.proxyFetch.state");

function getPatchState(): PatchState {
  const scopedGlobal = globalThis as typeof globalThis & {
    [PATCH_STATE_KEY]?: PatchState;
  };

  if (!scopedGlobal[PATCH_STATE_KEY]) {
    scopedGlobal[PATCH_STATE_KEY] = {
      originalFetch: globalThis.fetch,
      proxyContext: new AsyncLocalStorage(),
      isPatched: false,
    };
  }
  return scopedGlobal[PATCH_STATE_KEY];
}

const patchState = getPatchState();
const originalFetch = patchState.originalFetch;
const originalFetchWithDispatcher = originalFetch as FetchWithDispatcher;
const proxyContext = patchState.proxyContext;

function noProxyMatch(targetUrl) {
  const noProxy = process.env.NO_PROXY || process.env.no_proxy;
  if (!noProxy) return false;

  let target;
  try {
    target = new URL(targetUrl);
  } catch {
    return false;
  }

  const hostname = target.hostname.toLowerCase();
  const port = target.port || (target.protocol === "https:" ? "443" : "80");
  const patterns = noProxy
    .split(",")
    .map((p) => p.trim().toLowerCase())
    .filter(Boolean);

  return patterns.some((pattern) => {
    if (pattern === "*") return true;

    const [patternHost, patternPort] = pattern.split(":");
    if (patternPort && patternPort !== port) return false;

    if (!patternHost) return false;

    // Support wildcard matching (e.g. 192.168.* or *.local).
    // Uses a linear glob scan instead of dynamic RegExp to avoid ReDoS.
    if (patternHost.includes("*")) {
      const parts = patternHost.split("*");
      let pos = 0;
      let ok = hostname.startsWith(parts[0]);
      if (ok) {
        pos = parts[0].length;
        for (let i = 1; i < parts.length && ok; i++) {
          const seg = parts[i];
          if (i === parts.length - 1) {
            ok = seg === "" || (hostname.endsWith(seg) && hostname.length - seg.length >= pos);
          } else {
            const idx = seg ? hostname.indexOf(seg, pos) : pos;
            if (idx === -1) {
              ok = false;
            } else {
              pos = idx + seg.length;
            }
          }
        }
      }
      if (ok) return true;
    }

    if (patternHost.startsWith(".")) {
      return hostname.endsWith(patternHost) || hostname === patternHost.slice(1);
    }
    return hostname === patternHost || hostname.endsWith(`.${patternHost}`);
  });
}

function isLocalAddress(hostname: string): boolean {
  const host = hostname
    .replace(/^\[/, "")
    .replace(/\]$/, "")
    .replace(/^::ffff:/i, "");
  if (host === "localhost" || host === "0.0.0.0" || host === "127.0.0.1" || host === "::1") {
    return true;
  }
  if (host.endsWith(".local") || host.endsWith(".lan") || host.endsWith(".internal")) return true;
  // RFC1918 + loopback + link-local (169.254, incl. cloud metadata 169.254.169.254)
  // + CGNAT (100.64/10). 127/8 covers all loopback, not just 127.0.0.1.
  if (host.startsWith("192.168.")) return true;
  if (host.startsWith("10.")) return true;
  if (host.startsWith("127.")) return true;
  if (host.startsWith("169.254.")) return true;
  if (/^172\.(1[6-9]|2\d|3[0-1])\./.test(host)) return true;
  if (/^100\.(6[4-9]|[7-9]\d|1[01]\d|12[0-7])\./.test(host)) return true;
  // IPv6 ULA (fc00::/7 → fc/fd prefix) and link-local (fe80::/10)
  if (/^f[cd][0-9a-f]*:/i.test(host) || host.startsWith("fe80:")) return true;
  return false;
}

function resolveEnvProxyUrl(targetUrl) {
  if (noProxyMatch(targetUrl)) return null;

  let protocol;
  try {
    protocol = new URL(targetUrl).protocol;
  } catch {
    return null;
  }

  const proxyUrl =
    protocol === "https:"
      ? process.env.HTTPS_PROXY ||
        process.env.https_proxy ||
        process.env.ALL_PROXY ||
        process.env.all_proxy
      : process.env.HTTP_PROXY ||
        process.env.http_proxy ||
        process.env.ALL_PROXY ||
        process.env.all_proxy;

  if (!proxyUrl) return null;
  return normalizeProxyUrl(proxyUrl, "environment proxy");
}

export function resolveProxyForRequest(targetUrl) {
  let target;
  try {
    target = new URL(targetUrl);
  } catch {
    target = null;
  }

  // Always bypass proxy for local/LAN addresses
  if (target && isLocalAddress(target.hostname.toLowerCase())) {
    return { source: "direct", proxyUrl: null };
  }

  const contextProxy = proxyContext.getStore();
  if (contextProxy) {
    return { source: "context", proxyUrl: proxyConfigToUrl(contextProxy) };
  }

  const envProxyUrl = resolveEnvProxyUrl(targetUrl);
  if (envProxyUrl) {
    return { source: "env", proxyUrl: envProxyUrl };
  }

  return { source: "direct", proxyUrl: null };
}

function getTargetUrl(input) {
  if (typeof input === "string") return input;
  if (input && typeof input.url === "string") return input.url;
  return String(input);
}

export async function runWithProxyContext(
  proxyConfig,
  fn,
  opts?: { directFallbackOnUnreachable?: boolean }
) {
  if (typeof fn !== "function") {
    throw new TypeError("runWithProxyContext requires a callback function");
  }

  // Inherit existing context if no specific proxyConfig is provided
  const currentContext = proxyContext.getStore();
  const effectiveProxyConfig = proxyConfig || currentContext || null;

  const resolvedProxyUrl = effectiveProxyConfig ? proxyConfigToUrl(effectiveProxyConfig) : null;

  // The caller must opt in, and the runtime feature flag must also be enabled.
  // This fallback changes egress IP, so upgrades must not silently turn it on.
  const directFallbackOnUnreachable =
    opts?.directFallbackOnUnreachable === true && isControlPlaneProxyDirectFallbackEnabled();
  // Run fn with the proxy context cleared so the request egresses directly.
  const runDirect = () => proxyContext.run(null, fn);

  // T14: Proxy Fast-Fail
  // Perform a short TCP reachability check before issuing upstream requests.
  // Skip for edge-relay types (vercel / deno): proxyConfigToUrl returns
  // "https://<host>" which is the relay endpoint itself, not an HTTP proxy —
  // the actual routing is handled via x-relay-* headers below.
  const isVercelRelay = isRelayType((effectiveProxyConfig as { type?: string })?.type);
  if (resolvedProxyUrl && !isVercelRelay) {
    const reachable = await isProxyReachable(resolvedProxyUrl);
    if (!reachable) {
      const proxyLabel = proxyUrlForLogs(resolvedProxyUrl);
      if (directFallbackOnUnreachable) {
        console.warn(
          `[ProxyFetch] Proxy unreachable (${proxyLabel}); using a direct connection for this request.`
        );
        return runDirect();
      }
      const err = new Error(`[Proxy Fast-Fail] Proxy unreachable: ${proxyLabel}`) as Error & {
        code?: string;
        statusCode?: number;
      };
      err.code = "PROXY_UNREACHABLE";
      err.statusCode = 503;
      throw err;
    }
  }

  // Fail-closed family check: when the proxy URL carries a ?family=ipv6|ipv4 marker
  // (set for HOSTNAME proxies by proxyConfigToUrl), verify the hostname actually has a
  // record in that family before egressing. Refuse early rather than silently fall back
  // to the other family. No-op for IP literals (their family is intrinsic).
  if (resolvedProxyUrl && !isVercelRelay) {
    try {
      const u = new URL(resolvedProxyUrl);
      const fam = u.searchParams.get("family");
      if (fam === "ipv6" || fam === "ipv4") {
        const { assertHostnameSupportsFamily } = await import("./proxyFamilyResolve.ts");
        await assertHostnameSupportsFamily(u.hostname, fam === "ipv6" ? 6 : 4);
      }
    } catch (familyErr) {
      if (directFallbackOnUnreachable) {
        console.warn(
          `[ProxyFetch] Proxy family pre-check failed (${proxyUrlForLogs(resolvedProxyUrl)}); using a direct connection for this request.`
        );
        return runDirect();
      }
      const e = familyErr as Error & { code?: string; statusCode?: number };
      e.code = e.code || "PROXY_FAMILY_UNAVAILABLE";
      e.statusCode = e.statusCode || 503;
      throw e;
    }
  }

  return proxyContext.run(effectiveProxyConfig, async () => {
    if (resolvedProxyUrl && effectiveProxyConfig !== currentContext) {
      console.log(
        `[ProxyFetch] Applied request proxy context: ${proxyUrlForLogs(resolvedProxyUrl)}`
      );
    }
    return fn();
  });
}

/**
 * Like {@link runWithProxyContext}, but if the assigned proxy is unreachable or fails
 * its pre-checks the request can degrade to a DIRECT connection instead of throwing.
 *
 * For control-plane flows — OAuth code/token exchange, connection tests, token refresh —
 * where a dead pinned proxy must not block reaching the upstream (it otherwise surfaces
 * as a generic "Internal server error"). Data-plane chat keeps strict pinning via
 * runWithProxyContext so per-account egress-IP isolation is preserved.
 *
 * This remains disabled unless OMNIROUTE_CONTROL_PLANE_PROXY_DIRECT_FALLBACK is enabled
 * from Feature Flags or the environment.
 */
export async function runWithProxyContextOrDirect(proxyConfig, fn) {
  return runWithProxyContext(proxyConfig, fn, { directFallbackOnUnreachable: true });
}

async function patchedFetch(
  input: RequestInfo | URL,
  options: FetchWithDispatcherOptions = {},
  deps: ProxyFetchDeps = {}
) {
  if (options?.dispatcher) {
    // When a dispatcher is present, we MUST use the undici library fetch
    // to ensure version compatibility. Node 22 built-in fetch (undici v6)
    // is incompatible with undici v8 dispatchers (missing onRequestStart, etc.)
    const _undiciDispatcher =
      deps.undiciFetch ?? (undiciFetch as unknown as (...args: unknown[]) => Promise<Response>);
    return _undiciDispatcher(input, options);
  }

  const targetUrl = getTargetUrl(input);
  let resolved;
  try {
    resolved = resolveProxyForRequest(targetUrl);
  } catch (error) {
    const message = error instanceof Error ? error.message : String(error);
    console.error(`[ProxyFetch] Proxy configuration error: ${message}`);
    throw error;
  }
  const { source, proxyUrl } = resolved;

  if (!proxyUrl) {
    // TLS fingerprint spoofing for direct connections (no proxy configured)
    if (isTlsFingerprintEnabled() && tlsClient.available) {
      try {
        const store = tlsFingerprintContext.getStore();
        if (store) store.used = true;
        return await tlsClient.fetch(targetUrl, {
          ...options,
          headers: options.headers,
          signal: options.signal ?? undefined,
        });
      } catch (error) {
        const message = error instanceof Error ? error.message : String(error);
        console.warn(
          `[ProxyFetch] TLS fingerprint failed, falling back to native fetch: ${message}`
        );
        const store = tlsFingerprintContext.getStore();
        if (store) store.used = false;
      }
    }
    // Direct connection (no proxy) — use undici with custom dispatcher for timeout control.
    // Falls back to original native fetch if dispatcher initialization fails (#1054).
    // Retries once on transient dispatcher errors before falling back (fix: proxyfetch-undici-retry).
    //
    // ReadableStream/Blob body guard: if the body is non-replayable, skip the retry because
    // the first attempt drains the stream; a second attempt would silently send an empty body.
    // ReadableStream check: cast through unknown to avoid explicit-any budget (T11).
    const _bodyUnknown = options.body as unknown;
    const bodyIsStream =
      _bodyUnknown !== null &&
      _bodyUnknown !== undefined &&
      typeof _bodyUnknown === "object" &&
      (typeof (_bodyUnknown as Record<string, unknown>).getReader === "function" || // ReadableStream
        typeof (_bodyUnknown as Record<string, unknown>).stream === "function"); // Blob
    const maxAttempts = bodyIsStream ? 1 : 2;
    const _undiciDirect =
      deps.undiciFetch ?? (undiciFetch as unknown as (...args: unknown[]) => Promise<Response>);
    const _nativeFallback =
      (deps.nativeFetch as FetchWithDispatcher | undefined) ?? originalFetchWithDispatcher;
    let lastDispatcherError: unknown = null;
    for (let attempt = 0; attempt < maxAttempts; attempt++) {
      try {
        return await _undiciDirect(input, {
          ...options,
          // #4252: first attempt uses the pooled keep-alive dispatcher; a retry
          // (after a transient socket error) uses the no-keep-alive dispatcher so
          // it opens a FRESH socket instead of grabbing another stale pooled one
          // — the burst pattern was the retry re-hitting a dead pooled socket and
          // then falling through to native fetch (which also pools) → 502.
          dispatcher: attempt === 0 ? getDefaultDispatcher() : getRetryDispatcher(),
        });
      } catch (dispatcherError) {
        const msg =
          dispatcherError instanceof Error ? dispatcherError.message : String(dispatcherError);
        // CAUTION: Do NOT fallback to native fetch if the error is a version mismatch (invalid onRequestStart)
        // because the native fetch will definitely fail with the undici v8 dispatcher.
        if (msg.includes("onRequestStart")) {
          console.error(
            `[ProxyFetch] Fatal version mismatch: Dispatcher (v8) vs Fetch (v6/native). Hardware upgrade or SOCKS5 config isolation required. Error: ${msg}`
          );
          throw dispatcherError;
        }
        // Only retry/fallback for connection/dispatcher errors, not HTTP errors.
        // Prefer the .code property when available (more stable across undici
        // versions than message-string matching); fall back to substring match
        // for errors that lack a structured code.
        const errCode = (dispatcherError as { code?: unknown })?.code;
        if (
          msg.includes("fetch failed") ||
          errCode === "ECONNREFUSED" ||
          msg.includes("ECONNREFUSED") ||
          (typeof errCode === "string" && errCode.startsWith("UND_ERR")) ||
          msg.includes("UND_ERR")
        ) {
          if (attempt === 0 && maxAttempts > 1) {
            // First failure — retry once with a short jittered delay before giving up.
            lastDispatcherError = dispatcherError;
            await new Promise((r) => setTimeout(r, 25 + Math.random() * 50));
            continue;
          }
          // All attempts exhausted — try proxy fallback before native fetch
          if (source === "direct" && isFeatureFlagEnabled("PROXY_AUTO_SELECT_ENABLED")) {
            let targetHostname = "";
            try {
              targetHostname = new URL(targetUrl).hostname;
            } catch {
              // ignore
            }
            if (targetHostname) {
              const fallbackProxyUrl = await findWorkingProxy(targetHostname, targetUrl);
              if (fallbackProxyUrl) {
                try {
                  const dispatcher = createProxyDispatcher(fallbackProxyUrl);
                  return await _undiciDirect(input, { ...options, dispatcher });
                } catch {
                  // Proxy also failed — fall through to native fetch
                }
              }
            }
          }
          // Preserve original phrase intact for monitoring: "Undici dispatcher failed, falling back to native fetch"
          // #4252: append the flattened err.cause (code/syscall/errno/address) — the bare
          // "fetch failed" message hides what actually broke, making bursts undiagnosable.
          console.warn(
            `[ProxyFetch] Undici dispatcher failed, falling back to native fetch (after retry): ${describeFetchCause(dispatcherError)}`
          );
          try {
            return await _nativeFallback(input, options);
          } catch (nativeError) {
            // #4252: both the undici dispatcher AND native fetch failed. Surface BOTH
            // causes (server log) and tag the propagated error so the combo executor sees
            // a diagnosable failure IMMEDIATELY instead of a bare "fetch failed" — the
            // latter left jobs sitting until the 30s semaphore queue timeout, which then
            // tripped the circuit breaker.
            const detail = `dispatcher=[${describeFetchCause(dispatcherError)}] native=[${describeFetchCause(nativeError)}]`;
            console.warn(`[ProxyFetch] native fetch fallback ALSO failed: ${detail}`);
            if (nativeError instanceof Error) {
              (nativeError as Error & { proxyFetchDetail?: string }).proxyFetchDetail = detail;
            }
            throw nativeError;
          }
        }
        throw dispatcherError;
      }
    }
    // Should not be reached, but satisfy TypeScript control-flow.
    throw lastDispatcherError;
  }

  // Edge relay (vercel / deno): instead of routing through an HTTP proxy
  // dispatcher, we send x-relay-* headers to the edge function which forwards
  // the request upstream. Both backends share the same envelope shape.
  const contextProxy = proxyContext.getStore();
  if (
    contextProxy &&
    typeof contextProxy === "object" &&
    isRelayType((contextProxy as { type?: string }).type)
  ) {
    const vc = contextProxy as { type?: string; host?: string; relayAuth?: string };
    if (!vc.relayAuth) {
      // Generic message without internal labels — this throw can bubble up to
      // catch blocks that put error.message in response bodies (combo per-model
      // timeout, executor catch-all). Don't leak "[ProxyFetch]" diagnostics.
      const label = vc.type === "vercel" ? "Vercel relay" : `${vc.type || "Edge"} relay`;
      throw new Error(`${label} configuration error: missing relayAuth`);
    }
    const targetUrl = getTargetUrl(input);
    const relayHeaders = buildVercelRelayHeaders(targetUrl, vc.relayAuth);
    const mergedHeaders = new Headers(options?.headers);
    for (const [k, v] of Object.entries(relayHeaders)) mergedHeaders.set(k, v);
    // Pass host through proxyUrlForLogs so the same redaction policy applies
    // to relay routing logs (the rest of this module already follows that rule).
    const hostForLogs = proxyUrlForLogs(vc.host ? `https://${vc.host}` : "");
    if (process.env.OMNIROUTE_PROXY_FETCH_DEBUG === "true") {
      console.debug(`[ProxyFetch] Routing via ${vc.type || "edge"} relay: ${hostForLogs}`);
    }
    return await originalFetch(`https://${vc.host}`, {
      ...options,
      headers: mergedHeaders,
      duplex: "half",
    });
  }

  try {
    const dispatcher = createProxyDispatcher(proxyUrl);
    const _undiciProxy =
      deps.undiciFetch ?? (undiciFetch as unknown as (...args: unknown[]) => Promise<Response>);
    return await _undiciProxy(input, {
      ...options,
      dispatcher,
    });
  } catch (error) {
    const message = error instanceof Error ? error.message : String(error);
    console.error(`[ProxyFetch] Proxy request failed (${source}, fail-closed): ${message}`);
    throw error;
  }
}

/**
 * Named export for proxyFetch — identical to the patched globalThis.fetch but
 * accepts an optional ProxyFetchDeps for unit test dependency injection.
 * Production code should use globalThis.fetch (or the default export) instead.
 */
export async function proxyFetch(
  input: RequestInfo | URL,
  options: RequestInit = {},
  deps: ProxyFetchDeps = {}
): Promise<Response> {
  return patchedFetch(input, options as FetchWithDispatcherOptions, deps);
}

if (!isCloud && !patchState.isPatched) {
  globalThis.fetch = patchedFetch;
  patchState.isPatched = true;
}

/**
 * Run a function with TLS fingerprint tracking context.
 * After fn completes, returns { result, tlsFingerprintUsed }.
 */
export async function runWithTlsTracking(fn) {
  const store = { used: false };
  const result = await tlsFingerprintContext.run(store, fn);
  return { result, tlsFingerprintUsed: store.used };
}

/** Check if TLS fingerprint is enabled and available */
export function isTlsFingerprintActive() {
  return isTlsFingerprintEnabled() && tlsClient.available;
}

/**
 * Get the original unpatched global fetch function (Node.js native fetch
 * before the proxy/TLS fingerprint patch was applied).
 * Use this to bypass the patched fetch for specific requests when the
 * proxy dispatcher has compatibility issues with a particular endpoint.
 */
export function getOriginalFetch(): typeof globalThis.fetch {
  return originalFetch;
}

export default isCloud ? originalFetch : patchedFetch;