http: fix build on OpenSSL 4.0

.github/workflows/python-wheels.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, ubuntu-24.04-arm, macos-latest]
+        os: [ubuntu-latest, ubuntu-24.04-arm, macos-15]
 
     steps:
       - uses: actions/checkout@v7

CMakeLists.txt

@@ -10,7 +10,7 @@ if(POLICY CMP0167)
 endif()
 
 set (opendht_VERSION_MAJOR 4)
-set (opendht_VERSION_MINOR 1.1)
+set (opendht_VERSION_MINOR 2.0)
 set (opendht_VERSION ${opendht_VERSION_MAJOR}.${opendht_VERSION_MINOR})
 set (PACKAGE_VERSION ${opendht_VERSION})
 set (VERSION "${opendht_VERSION}")

meson.build

@@ -5,7 +5,7 @@ project(
     'cython',
     license: 'MIT',
     license_files: 'LICENSE',
-    version: '4.1.1',
+    version: '4.2.0',
     meson_version: '>=1.1.0',
     default_options: ['cpp_std=c++20', 'warning_level=3'],
 )

src/http.cpp

@@ -302,7 +302,7 @@ static X509*
 issuer_from_chain(STACK_OF(X509) * fullchain)
 {
     X509 *cert, *issuer;
-    X509_NAME* issuer_name;
+    const X509_NAME* issuer_name;
 
     cert = cert_from_chain(fullchain);
     if ((issuer_name = X509_get_issuer_name(cert)) == nullptr)
@@ -917,8 +917,16 @@ Resolver::add_callback(ResolverCb cb, sa_family_t family)
                                                else
                                                    cb(ec, filter(endpoints, family));
                                            });
-    else
-        cb(ec_, family == AF_UNSPEC ? endpoints_ : filter(endpoints_, family));
+    else {
+        // Always dispatch the callback on the io_context thread. Invoking it
+        // synchronously would run the caller's continuation (e.g. the whole
+        // connect chain of Request::send) on the calling thread, mutating asio
+        // objects concurrently with the io thread running the io_context.
+        asio::post(resolver_.get_executor(),
+                   [cb = std::move(cb),
+                    ec = ec_,
+                    endpoints = family == AF_UNSPEC ? endpoints_ : filter(endpoints_, family)] { cb(ec, endpoints); });
+    }
 }
 
 void

tests/test_http.cpp

@@ -8,6 +8,7 @@
 
 #include <iostream>
 #include <string>
+#include <atomic>
 #include <chrono>
 #include <condition_variable>
 
@@ -332,6 +333,36 @@ HttpTester::test_parse_url_just_slash()
     CPPUNIT_ASSERT_EQUAL(std::string("/"), parsed.target);
 }
 
+void
+HttpTester::test_completed_resolver_callback_uses_io_thread()
+{
+    asio::io_context ioContext;
+    const asio::ip::tcp::endpoint endpoint(asio::ip::address_v4::loopback(), 80);
+    dht::http::Resolver resolver(ioContext, {endpoint});
+    const auto callerThread = std::this_thread::get_id();
+    std::thread::id callbackThread;
+    asio::error_code callbackError;
+    std::vector<asio::ip::tcp::endpoint> resolvedEndpoints;
+    std::atomic_bool callbackCalled {false};
+
+    resolver.add_callback([&](const asio::error_code& ec, const auto& endpoints) {
+        callbackError = ec;
+        callbackThread = std::this_thread::get_id();
+        resolvedEndpoints = endpoints;
+        callbackCalled = true;
+    });
+
+    CPPUNIT_ASSERT(!callbackCalled);
+    std::thread ioThread([&] { ioContext.run(); });
+    ioThread.join();
+
+    CPPUNIT_ASSERT(callbackCalled);
+    CPPUNIT_ASSERT(!callbackError);
+    CPPUNIT_ASSERT(callbackThread != callerThread);
+    CPPUNIT_ASSERT_EQUAL(size_t(1), resolvedEndpoints.size());
+    CPPUNIT_ASSERT_EQUAL(endpoint, resolvedEndpoints.front());
+}
+
 void
 HttpTester::test_send_json()
 {

tests/test_http.h

@@ -39,6 +39,7 @@ class HttpTester : public CppUnit::TestFixture
     CPPUNIT_TEST(test_parse_url_complex_path_query_fragment);
     CPPUNIT_TEST(test_parse_url_empty);
     CPPUNIT_TEST(test_parse_url_just_slash);
+    CPPUNIT_TEST(test_completed_resolver_callback_uses_io_thread);
     // send
     CPPUNIT_TEST(test_send_json);
     CPPUNIT_TEST_SUITE_END();
@@ -82,6 +83,7 @@ public:
     void test_parse_url_complex_path_query_fragment();
     void test_parse_url_empty();
     void test_parse_url_just_slash();
+    void test_completed_resolver_callback_uses_io_thread();
     /**
      * Test send(json)
      */

vcpkg.json

@@ -1,6 +1,6 @@
 {
   "name": "opendht",
-  "version-string": "4.1.1",
+  "version-string": "4.2.0",
   "port-version": 1,
   "description": "OpenDHT: A lightweight C++17 Distributed Hash Table library.",
   "homepage": "https://opendht.net",