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from fastapi import FastAPI, Request, HTTPException |
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from fastapi.responses import HTMLResponse, Response |
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from urllib.parse import urlparse, urljoin, quote |
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import httpx |
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from bs4 import BeautifulSoup |
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app = FastAPI() |
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INDEX_HTML = """ |
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<!DOCTYPE html> |
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<html lang="zh-CN"> |
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<head> |
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<meta charset="UTF-8" /> |
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<title>简单反向代理</title> |
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<meta name="viewport" content="width=device-width, initial-scale=1" /> |
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<style> |
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body { font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif; |
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background: #0f172a; color: #e5e7eb; display: flex; align-items: center; |
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justify-content: center; min-height: 100vh; margin: 0; } |
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.card { background: #020617; border-radius: 16px; padding: 32px; max-width: 600px; |
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width: 100%; box-shadow: 0 24px 60px rgba(0,0,0,0.6); border: 1px solid #1e293b;} |
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h1 { margin-top: 0; font-size: 24px; margin-bottom: 8px;} |
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p { margin-top: 0; margin-bottom: 16px; color: #9ca3af; font-size: 14px;} |
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form { display: flex; gap: 8px; } |
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input[type="url"] { |
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flex: 1; padding: 10px 12px; border-radius: 999px; border: 1px solid #334155; |
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background: #020617; color: #e5e7eb; font-size: 14px; outline: none; |
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} |
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input[type="url"]::placeholder { color: #6b7280; } |
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button { |
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padding: 10px 18px; border-radius: 999px; border: none; cursor: pointer; |
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font-size: 14px; font-weight: 600; background: #22c55e; color: #022c22; |
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} |
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button:hover { filter: brightness(1.05); } |
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small { color: #6b7280; font-size: 12px; display: block; margin-top: 12px;} |
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</style> |
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</head> |
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<body> |
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<main class="card"> |
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<h1>🔁 简单反向代理</h1> |
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<p>输入一个要访问的 URL，例如 <code>https://example.com</code>。</p> |
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<form action="/proxy" method="get"> |
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<input |
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type="url" |
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name="url" |
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placeholder="https://example.com" |
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required |
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/> |
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<button type="submit">Go</button> |
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</form> |
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<small>仅支持公开的 http/https 网址，部分复杂 / 需要登录的网站可能无法正常工作。</small> |
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</main> |
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</body> |
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</html> |
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""" |
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@app.get("/", response_class=HTMLResponse) |
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async def index(): |
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return INDEX_HTML |
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def normalize_url(raw: str) -> str: |
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"""如果没有 scheme，自动加上 http://""" |
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raw = raw.strip() |
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if not raw: |
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raise ValueError("空 URL") |
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parsed = urlparse(raw) |
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if not parsed.scheme: |
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raw = "http://" + raw |
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return raw |
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def is_allowed_url(url: str) -> bool: |
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"""限制只能访问公网 http/https，简单阻断本地 / 内网地址。""" |
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parsed = urlparse(url) |
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if parsed.scheme not in ("http", "https"): |
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return False |
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host = (parsed.hostname or "").lower() |
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if host in ("localhost", "127.0.0.1"): |
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return False |
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private_prefixes = ( |
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"10.", |
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"192.168.", |
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"172.16.", "172.17.", "172.18.", "172.19.", |
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"172.20.", "172.21.", "172.22.", "172.23.", |
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"172.24.", "172.25.", "172.26.", "172.27.", |
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"172.28.", "172.29.", "172.30.", "172.31.", |
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) |
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if any(host.startswith(p) for p in private_prefixes): |
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return False |
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return True |
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HOP_BY_HOP_HEADERS = { |
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"connection", |
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"keep-alive", |
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"proxy-authenticate", |
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"proxy-authorization", |
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"te", |
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"trailers", |
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"transfer-encoding", |
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"upgrade", |
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} |
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BLOCKED_HEADERS = { |
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"x-frame-options", |
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"content-security-policy", |
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} |
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def rewrite_html(html: str, base_url: str) -> str: |
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"""重写 HTML 中的链接，使站内跳转继续走 /proxy。""" |
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soup = BeautifulSoup(html, "html.parser") |
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tag_attr_pairs = [ |
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("a", "href"), |
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("link", "href"), |
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("img", "src"), |
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("script", "src"), |
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("iframe", "src"), |
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("source", "src"), |
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("video", "src"), |
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("form", "action"), |
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] |
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for tag, attr in tag_attr_pairs: |
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for node in soup.find_all(tag): |
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value = node.get(attr) |
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if not value: |
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continue |
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low = value.lower().strip() |
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if low.startswith("#") or low.startswith("javascript:"): |
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continue |
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absolute = urljoin(base_url, value) |
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proxied = f"/proxy?url={quote(absolute, safe='')}" |
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node[attr] = proxied |
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return str(soup) |
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@app.api_route( |
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"/proxy", |
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methods=["GET", "POST", "PUT", "PATCH", "DELETE", "HEAD", "OPTIONS"], |
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) |
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async def proxy(request: Request, url: str): |
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try: |
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target_url = normalize_url(url) |
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except ValueError: |
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raise HTTPException(status_code=400, detail="无效 URL") |
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if not is_allowed_url(target_url): |
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raise HTTPException( |
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status_code=400, |
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detail="仅支持公网 http/https 地址，且不允许访问内网 / 本地地址。", |
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) |
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outgoing_headers = {} |
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for k, v in request.headers.items(): |
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lk = k.lower() |
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if lk in HOP_BY_HOP_HEADERS: |
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continue |
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if lk in ("host", "accept-encoding"): |
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continue |
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outgoing_headers[k] = v |
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outgoing_headers["Accept-Encoding"] = "identity" |
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body = await request.body() |
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async with httpx.AsyncClient( |
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follow_redirects=True, |
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timeout=20.0, |
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) as client: |
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upstream_resp = await client.request( |
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request.method, |
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target_url, |
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content=body if request.method not in ("GET", "HEAD") else None, |
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headers=outgoing_headers, |
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) |
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content_type = (upstream_resp.headers.get("content-type") or "").lower() |
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response_headers = {} |
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for k, v in upstream_resp.headers.items(): |
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lk = k.lower() |
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if lk in HOP_BY_HOP_HEADERS: |
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continue |
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if lk in ("content-length", "content-encoding"): |
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continue |
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if lk in BLOCKED_HEADERS: |
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continue |
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response_headers[k] = v |
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if "text/html" in content_type or "application/xhtml+xml" in content_type: |
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html_text = upstream_resp.text |
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rewritten_html = rewrite_html(html_text, base_url=str(upstream_resp.url)) |
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return HTMLResponse( |
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content=rewritten_html, |
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status_code=upstream_resp.status_code, |
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headers=response_headers, |
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media_type="text/html; charset=utf-8", |
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) |
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if ( |
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content_type.startswith("image/") |
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or content_type.startswith("video/") |
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or content_type.startswith("audio/") |
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or "font" in content_type |
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or content_type in ( |
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"text/css", |
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"application/javascript", |
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"text/javascript", |
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"application/x-javascript", |
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) |
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): |
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return Response( |
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content=upstream_resp.content, |
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status_code=upstream_resp.status_code, |
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headers=response_headers, |
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media_type=content_type or None, |
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) |
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if "content-disposition" not in {k.lower(): v for k, v in response_headers.items()}: |
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response_headers["Content-Disposition"] = "attachment; filename=downloaded.bin" |
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return Response( |
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content=upstream_resp.content, |
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status_code=upstream_resp.status_code, |
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headers=response_headers, |
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media_type=content_type or "application/octet-stream", |
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) |
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