mirror of
https://github.com/yhirose/cpp-httplib.git
synced 2026-09-02 06:43:48 +00:00
254e576b50
* Add Server::CustomRoute() for HTTP methods outside the built-in set parse_request_line validates the request method against a fixed whitelist and rejects anything else with 400 before routing runs. That blocks WebDAV, where PROPFIND, PROPPATCH, MKCOL, COPY, MOVE, LOCK and UNLOCK are ordinary methods defined by RFC 4918, and it blocks extension methods such as UPnP's SUBSCRIBE. The need has been open since #847. Registering a handler is now what makes the server accept a method: svr.CustomRoute("PROPFIND", "/dav/:id", handler); Because custom methods go through the normal dispatch path, patterns work the way they do for Get() and friends, and the request body is available in req.body. Serving these methods through set_pre_routing_handler was never enough: the body has not been read at that point, so PROPPATCH and LOCK, which require one, could not be implemented at all. A HandlerWithContentReader overload is available too. The content reader gate in routing() also fires when a custom method carries no body, matching what expect_content() does unconditionally for POST/PUT/PATCH/DELETE, so a body-less PROPFIND (RFC 4918 treats one as allprop) reaches its handler instead of falling through to 404. Method names are validated as RFC 9110 tokens, and the ten built-in methods are refused. Seven of them are dispatched by the if/else chain in routing() before the custom tables are consulted, so a route registered for one could never fire; CONNECT, TRACE and PRI carry protocol-level meaning this library does not route. A refused registration makes is_valid() return false, so listen() fails rather than starting a server holding a handler that would never run. This is also why SSLServer::is_valid() now chains to Server::is_valid() instead of only checking ctx_. Servers that never call CustomRoute() keep the previous per-request cost: the built-in method set is checked first and short-circuits, and the custom lookup returns early on an empty map. * Add cookbook recipe for custom HTTP methods The CustomRoute() docs were a section inside S01, which pushed that page to 90 lines, the longest in the cookbook, and mixed a separate feature into a page about registering GET/POST/PUT/DELETE handlers. Move the section into its own recipe and give it room for the part that was missing: the OPTIONS handler returning DAV: and Allow, which WebDAV clients probe for before anything else. S01 goes back to 68 lines and keeps a pointer to the new page. The recipe is titled after the API rather than after WebDAV, and says outright that generating the 207 Multi-Status XML, interpreting Depth and managing locks are the reader's job. Routing the method is all the library does. S23 takes order 42, so the TLS, SSE and WebSocket recipes shift to 43-57. That only moves the sort key. Filenames, the T01/E01/W01 labels, the published URLs and every cross-reference are untouched.
86 lines
3.5 KiB
Markdown
86 lines
3.5 KiB
Markdown
---
|
|
title: "E03. SSEの再接続を処理する"
|
|
order: 50
|
|
status: "draft"
|
|
---
|
|
|
|
SSE接続はネットワークの都合で切れることがあります。クライアントは自動的に再接続を試みるので、サーバー側では「再接続してきたクライアントに、途中から配信を再開する」仕組みを用意しておくと親切です。
|
|
|
|
## `Last-Event-ID`を受け取る
|
|
|
|
クライアントが再接続すると、最後に受け取ったイベントのIDを`Last-Event-ID`ヘッダーに入れて送ってきます。サーバー側ではこれを読んで、その続きから配信を再開できます。
|
|
|
|
```cpp
|
|
svr.Get("/events", [](const httplib::Request &req, httplib::Response &res) {
|
|
auto last_id = req.get_header_value("Last-Event-ID");
|
|
int start = last_id.empty() ? 0 : std::stoi(last_id) + 1;
|
|
|
|
res.set_chunked_content_provider(
|
|
"text/event-stream",
|
|
[start](size_t offset, httplib::DataSink &sink) mutable {
|
|
static int next_id = 0;
|
|
if (next_id < start) { next_id = start; }
|
|
|
|
std::string msg = "id: " + std::to_string(next_id) + "\n"
|
|
+ "data: event " + std::to_string(next_id) + "\n\n";
|
|
sink.write(msg.data(), msg.size());
|
|
++next_id;
|
|
|
|
std::this_thread::sleep_for(std::chrono::seconds(1));
|
|
return true;
|
|
});
|
|
});
|
|
```
|
|
|
|
初回接続では`Last-Event-ID`が無いので`0`から送り始め、再接続時は続きのIDから再開します。イベントの保存はサーバー側の責任なので、直近のイベントをキャッシュしておく必要があります。
|
|
|
|
## 再接続間隔を指定する
|
|
|
|
`retry:`フィールドを送ると、クライアント側の再接続間隔を指定できます。単位はミリ秒です。
|
|
|
|
```cpp
|
|
std::string msg = "retry: 5000\n\n"; // 5秒後に再接続
|
|
sink.write(msg.data(), msg.size());
|
|
```
|
|
|
|
通常は最初に1回送っておけば十分です。混雑時やサーバーメンテナンス時に、リトライ間隔を長めに指定して負荷を減らすといった使い方もできます。
|
|
|
|
## イベントのバッファリング
|
|
|
|
再接続のために、直近のイベントをサーバー側でバッファしておく実装が必要です。
|
|
|
|
```cpp
|
|
struct EventBuffer {
|
|
std::mutex mu;
|
|
std::deque<std::pair<int, std::string>> events; // {id, data}
|
|
int next_id = 0;
|
|
|
|
void push(const std::string &data) {
|
|
std::lock_guard<std::mutex> lock(mu);
|
|
events.push_back({next_id++, data});
|
|
if (events.size() > 1000) { events.pop_front(); }
|
|
}
|
|
|
|
std::vector<std::pair<int, std::string>> since(int id) {
|
|
std::lock_guard<std::mutex> lock(mu);
|
|
std::vector<std::pair<int, std::string>> out;
|
|
for (const auto &e : events) {
|
|
if (e.first >= id) { out.push_back(e); }
|
|
}
|
|
return out;
|
|
}
|
|
};
|
|
```
|
|
|
|
再接続してきたクライアントに`since(last_id)`で未送信分をまとめて送ると、取りこぼしを防げます。
|
|
|
|
## 保存期間のバランス
|
|
|
|
バッファをどれだけ持つかは、メモリと「どれだけさかのぼって再送できるか」のトレードオフです。用途によって決めましょう。
|
|
|
|
- リアルタイムチャット: 数分〜数十分
|
|
- 通知: 直近のN件
|
|
- 取引データ: 永続化して、必要ならDBから取得
|
|
|
|
> **Warning:** `Last-Event-ID`はクライアントが送ってくる値なので、サーバー側で信用しすぎないようにしましょう。数値として読むなら範囲チェックを、文字列ならサニタイズを忘れずに。
|