Carry the CA store and session verifier over to the redirect client (#2632)

httplib.h

@@ -10998,6 +10998,28 @@ inline bool load_client_ca_config(tls::ctx_t ctx,
   return ret;
 }
 
+// Serializes the CA certificates installed in ctx as PEM, so they can be
+// loaded into another context.
+inline std::string ca_certs_to_pem(tls::ctx_t ctx) {
+  std::string pem;
+  std::vector<tls::cert_t> certs;
+  tls::get_ca_certs(ctx, certs);
+  for (auto cert : certs) {
+    std::vector<unsigned char> der;
+    if (tls::get_cert_der(cert, der)) {
+      auto b64 = base64_encode(std::string(der.begin(), der.end()));
+      pem += "-----BEGIN CERTIFICATE-----\n";
+      for (size_t i = 0; i < b64.size(); i += 64) {
+        pem += b64.substr(i, 64);
+        pem += '\n';
+      }
+      pem += "-----END CERTIFICATE-----\n";
+    }
+    tls::free_cert(cert);
+  }
+  return pem;
+}
+
 // The parts of session setup that only SSLClient needs, plus the handful
 // WebSocketClient also exposes; everything else takes the defaults, which is
 // what keeps the two clients on one implementation.
@@ -15903,6 +15925,27 @@ inline bool ClientImpl::create_redirect_client(
       redirect_client.set_ca_cert_path(ca_cert_file_path_, ca_cert_dir_path_);
     }
 
+    if (is_ssl()) {
+      auto &self = static_cast<SSLClient &>(*this);
+
+      // A store handed to set_ca_cert_store() is owned by ctx_ and leaves no
+      // PEM behind. Without it the redirect client would fall back to the
+      // system CAs and trust roots this client was configured to exclude.
+      if (self.ca_cert_store_set_) {
+        std::string pem;
+        {
+          std::lock_guard<std::mutex> guard(self.ctx_mutex_);
+          pem = detail::ca_certs_to_pem(self.ctx_);
+        }
+        if (!pem.empty()) {
+          redirect_client.load_ca_cert_store(pem.data(), pem.size());
+        }
+        redirect_client.ca_cert_store_set_ = true;
+      }
+
+      redirect_client.session_verifier_ = self.session_verifier_;
+    }
+
     // Client certificates are set through constructor for SSLClient
     // NOTE: SSLClient constructor already takes client_cert_path and
     // client_key_path so we need to create it properly if client certs are
@@ -21426,19 +21469,11 @@ inline size_t get_ca_certs(ctx_t ctx, std::vector<cert_t> &certs) {
   if (!ctx) { return 0; }
   auto *mbed_ctx = static_cast<impl::MbedTlsContext *>(ctx);
 
-  // Iterate through the CA chain
+  // Iterate through the CA chain. The certificates stay owned by the context,
+  // as free_cert() does not release anything on this backend.
   mbedtls_x509_crt *cert = &mbed_ctx->ca_chain;
   while (cert != nullptr && cert->raw.len > 0) {
-    // Create a copy of the certificate for the caller
+    certs.push_back(static_cast<cert_t>(cert));
-    auto *copy = new mbedtls_x509_crt;
-    mbedtls_x509_crt_init(copy);
-    int ret = mbedtls_x509_crt_parse_der(copy, cert->raw.p, cert->raw.len);
-    if (ret == 0) {
-      certs.push_back(static_cast<cert_t>(copy));
-    } else {
-      mbedtls_x509_crt_free(copy);
-      delete copy;
-    }
     cert = cert->next;
   }
   return certs.size();

test/test.cc

@@ -15919,6 +15919,103 @@ TEST(SSLClientRedirectTest, CertFile) {
   ASSERT_TRUE(res) << "Error: " << to_string(res.error());
   ASSERT_EQ(StatusCode::OK_200, res->status);
 }
+
+// A store set via set_ca_cert_store() must be carried over to the client that
+// follows a cross-host redirect, rather than replaced by the system CAs.
+TEST(SSLClientRedirectTest, SetCaCertStore) {
+  auto ssl_port = PORT + 1;
+
+  SSLServer ssl_svr1(SERVER_CERT2_FILE, SERVER_PRIVATE_KEY_FILE);
+  ASSERT_TRUE(ssl_svr1.is_valid());
+  ssl_svr1.Get("/index", [&](const Request &, Response &res) {
+    res.set_redirect("https://127.0.0.1:" + std::to_string(ssl_port) +
+                     "/index");
+  });
+
+  SSLServer ssl_svr2(SERVER_CERT2_FILE, SERVER_PRIVATE_KEY_FILE);
+  ASSERT_TRUE(ssl_svr2.is_valid());
+  ssl_svr2.Get("/index", [&](const Request &, Response &res) {
+    res.set_content("test", "text/plain");
+  });
+
+  thread t = thread([&]() { ASSERT_TRUE(ssl_svr1.listen("127.0.0.1", PORT)); });
+  thread t2 =
+      thread([&]() { ASSERT_TRUE(ssl_svr2.listen("127.0.0.1", ssl_port)); });
+  auto se = detail::scope_exit([&] {
+    ssl_svr2.stop();
+    ssl_svr1.stop();
+    t2.join();
+    t.join();
+    ASSERT_FALSE(ssl_svr1.is_running());
+  });
+
+  ssl_svr1.wait_until_ready();
+  ssl_svr2.wait_until_ready();
+
+  SSLClient cli("127.0.0.1", PORT);
+  std::string cert;
+  read_file(SERVER_CERT2_FILE, cert);
+  cli.set_ca_cert_store(tls::create_ca_store(cert.c_str(), cert.size()));
+  cli.enable_server_certificate_verification(true);
+  cli.set_follow_location(true);
+  cli.set_connection_timeout(30);
+
+  auto res = cli.Get("/index");
+  ASSERT_TRUE(res) << "Error: " << to_string(res.error());
+  ASSERT_EQ(StatusCode::OK_200, res->status);
+}
+
+// The session verifier must also run for the host a redirect leads to.
+TEST(SSLClientRedirectTest, SessionVerifier) {
+  auto ssl_port = PORT + 1;
+
+  SSLServer ssl_svr1(SERVER_CERT2_FILE, SERVER_PRIVATE_KEY_FILE);
+  ASSERT_TRUE(ssl_svr1.is_valid());
+  ssl_svr1.Get("/index", [&](const Request &, Response &res) {
+    res.set_redirect("https://127.0.0.1:" + std::to_string(ssl_port) +
+                     "/index");
+  });
+
+  SSLServer ssl_svr2(SERVER_CERT2_FILE, SERVER_PRIVATE_KEY_FILE);
+  ASSERT_TRUE(ssl_svr2.is_valid());
+  ssl_svr2.Get("/index", [&](const Request &, Response &res) {
+    res.set_content("test", "text/plain");
+  });
+
+  thread t = thread([&]() { ASSERT_TRUE(ssl_svr1.listen("127.0.0.1", PORT)); });
+  thread t2 =
+      thread([&]() { ASSERT_TRUE(ssl_svr2.listen("127.0.0.1", ssl_port)); });
+  auto se = detail::scope_exit([&] {
+    ssl_svr2.stop();
+    ssl_svr1.stop();
+    t2.join();
+    t.join();
+    ASSERT_FALSE(ssl_svr1.is_running());
+  });
+
+  ssl_svr1.wait_until_ready();
+  ssl_svr2.wait_until_ready();
+
+  SSLClient cli("127.0.0.1", PORT);
+  std::string cert;
+  read_file(SERVER_CERT2_FILE, cert);
+  cli.load_ca_cert_store(cert.c_str(), cert.size());
+  cli.enable_server_certificate_verification(true);
+  cli.set_follow_location(true);
+  cli.set_connection_timeout(30);
+
+  // Accept the first host only.
+  std::atomic<int> sessions{0};
+  cli.set_session_verifier([&](tls::session_t) -> SSLVerifierResponse {
+    return sessions++ == 0 ? SSLVerifierResponse::CertificateAccepted
+                           : SSLVerifierResponse::CertificateRejected;
+  });
+
+  auto res = cli.Get("/index");
+  ASSERT_FALSE(res);
+  EXPECT_EQ(Error::SSLServerVerification, res.error());
+  EXPECT_EQ(2, sessions.load());
+}
 #endif
 
 #ifdef CPPHTTPLIB_SSL_ENABLED