Replace libevent with our own HTTP and socket-handling implementation #35182

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Merged

fanquake merged 29 commits into bitcoin:master from pinheadmz:http-rewrite-30Apr2026

Jun 22, 2026

+2,471 −609

doc/developer-notes.md

            
                      Original file line number
                      Diff line number
                      Diff line change
                  
    @@ -703,7 +703,7 @@ and its `cs_KeyStore` lock for example).
  
      : Parallel script validation threads for transactions in blocks.

    - [ThreadHTTP (`b-http`)](https://doxygen.bitcoincore.org/httpserver_8cpp.html#http)

      : Libevent thread to listen for RPC and REST connections.

      : Thread to listen for RPC and REST connections.

    - [HTTP worker threads (`b-http.xx`)](https://doxygen.bitcoincore.org/httpserver_8cpp.html#http_pool)

      : Threads to service RPC and REST requests.

    @@ -716,7 +716,7 @@ and its `cs_KeyStore` lock for example).
  
      addrman and running asynchronous validationinterface callbacks.

    - [TorControlThread (`b-torcontrol`)](https://doxygen.bitcoincore.org/class_tor_controller.html#torcontrol)

      : Libevent thread for tor connections.

      : Thread for tor connections.

    - Net threads:

doc/release-notes-35182.md

-Original file line number
+Diff line change
@@ -0,0 +1,16 @@
+    HTTP: RPC / REST
+    ----------------
+    The HTTP server has been rewritten from scratch to replace libevent. (#35182)
+    `libevent` has been deprecated as a logging category and will be removed in
+    a future release. At that time configurations like `debugexclude=libevent` will
+    be invalid.
+    Certain HTTP edge cases will observe different behavior to be more RFC-compliant:
+    - Stricter enforcement of maximum headers size (8192 bytes)
+    - Reject requests with whitespace in header field-names
+    - "Line Folding" is rejected (whitespace at start of a header line)
+    - Tolerate `%` at the end of requested URLs
+    - Multiple "Content-Length" headers with different values are rejected

src/bitcoin-cli.cpp

            
                      Original file line number
                      Diff line number
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    @@ -104,7 +104,7 @@ void HTTPResponseHeaders::Read(util::LineReader& reader)
  
        // Headers https://httpwg.org/specs/rfc9110.html#rfc.section.6.3

        // A sequence of Field Lines https://httpwg.org/specs/rfc9110.html#rfc.section.5.2

        while (auto maybe_line = reader.ReadLine()) {

            const std::string& line = *maybe_line;

            const std::string_view line = *maybe_line;

            // An empty line indicates end of the headers section https://www.rfc-editor.org/rfc/rfc2616#section-4

            if (line.empty()) return;

    @@ -965,7 +965,7 @@ HTTPResponse HTTPClient::ReadResponse()
  
            throw HTTPError{"Failed to read status line"};

        }

        const std::string& status_str = *status_line;

        const std::string_view status_str = *status_line;

        // Minimum status line is "HTTP/X.Y NNN" (e.g. "HTTP/1.1 200"), 12 characters.

        if (status_str.size() < 12 || !status_str.starts_with("HTTP/")) {

            throw HTTPError{"Invalid status line"};

    @@ -976,7 +976,7 @@ HTTPResponse HTTPClient::ReadResponse()
  
            throw HTTPError{"Invalid status line format"};

        }

        std::string status_code_str = status_str.substr(space1 + 1, 3);

        const std::string_view status_code_str = status_str.substr(space1 + 1, 3);

        auto status_code = ToIntegral<int>(status_code_str);

        if (!status_code) {

            throw HTTPError{"Invalid status code"};

src/httprpc.cpp

-Original file line number
+Diff line change
@@ Expand Up / @@ -26,6 +26,7 @@ @@
     #include <string>
     #include <vector>
+    using http_bitcoin::HTTPRequest;
     using util::SplitString;
     using util::TrimStringView;
@@ Expand Down Expand Up @@
     static void HTTPReq_JSONRPC(const std::any& context, HTTPRequest* req)
     {
         // JSONRPC handles only POST
-        if (req->GetRequestMethod() != HTTPRequest::POST) {
+        if (req->GetRequestMethod() != HTTPRequestMethod::POST) {
             req->WriteReply(HTTP_BAD_METHOD, "JSONRPC server handles only POST requests");
             return;
         }
@@ Expand Down Expand Up / @@ -347,8 +348,6 @@ bool StartHTTPRPC(const std::any& context) @@
         if (g_wallet_init_interface.HasWalletSupport()) {
             RegisterHTTPHandler("/wallet/", false, handle_rpc);
         }
-        struct event_base* eventBase = EventBase();
-        assert(eventBase);
         return true;
     }
@@ Expand Down @@

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