Default using Windows Schannel for SSL/TLS on Windows

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https://learn.microsoft.com/en-us/windows/win32/api/wincrypt/nf-wincrypt-certgetcertificatechain
for related flags.

Closes #1978

Author: solarispika

CMakeLists.txt

@@ -11,6 +11,7 @@
 	* HTTPLIB_REQUIRE_ZSTD (default off)
 	* HTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN (default on)
 	* HTTPLIB_USE_NON_BLOCKING_GETADDRINFO (default on)
+	* HTTPLIB_USE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE (default on)
 	* HTTPLIB_COMPILE (default off)
 	* HTTPLIB_INSTALL (default on)
 	* HTTPLIB_SHARED (default off) builds as a shared library (if HTTPLIB_COMPILE is ON)
@@ -110,6 +111,7 @@ option(HTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN "Enable feature to load system cer
 option(HTTPLIB_USE_NON_BLOCKING_GETADDRINFO "Enables the non-blocking alternatives for getaddrinfo." ON)
 option(HTTPLIB_REQUIRE_ZSTD "Requires ZSTD to be found & linked, or fails build." OFF)
 option(HTTPLIB_USE_ZSTD_IF_AVAILABLE "Uses ZSTD (if available) to enable zstd support." ON)
+option(HTTPLIB_USE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE "Enable automatic root certificates update on Windows." ON)
 # Defaults to static library but respects standard BUILD_SHARED_LIBS if set
 include(CMakeDependentOption)
 cmake_dependent_option(HTTPLIB_SHARED "Build the library as a shared library instead of static. Has no effect if using header-only."
@@ -296,6 +298,7 @@ target_compile_definitions(${PROJECT_NAME} ${_INTERFACE_OR_PUBLIC}
 	$<$<BOOL:${HTTPLIB_IS_USING_OPENSSL}>:CPPHTTPLIB_OPENSSL_SUPPORT>
 	$<$<AND:$<PLATFORM_ID:Darwin>,$<BOOL:${HTTPLIB_IS_USING_OPENSSL}>,$<BOOL:${HTTPLIB_IS_USING_CERTS_FROM_MACOSX_KEYCHAIN}>>:CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN>
 	$<$<BOOL:${HTTPLIB_USE_NON_BLOCKING_GETADDRINFO}>:CPPHTTPLIB_USE_NON_BLOCKING_GETADDRINFO>
+	$<$<AND:$<PLATFORM_ID:Windows>,$<NOT:$<BOOL:${HTTPLIB_USE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE}>>>:CPPHTTPLIB_DISABLE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE>
 )
 
 # CMake configuration files installation directory

httplib.h

@@ -221,6 +221,10 @@ using ssize_t = __int64;
 #endif // NOMINMAX
 
 #include <io.h>
+#if defined(CPPHTTPLIB_OPENSSL_SUPPORT) &&                                     \
+    !defined(CPPHTTPLIB_DISABLE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE)
+#define CERT_CHAIN_PARA_HAS_EXTRA_FIELDS
+#endif
 #include <winsock2.h>
 #include <ws2tcpip.h>
 
@@ -6309,6 +6313,7 @@ inline bool is_ssl_peer_could_be_closed(SSL *ssl, socket_t sock) {
 }
 
 #ifdef _WIN32
+#ifdef CPPHTTPLIB_DISABLE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE
 // NOTE: This code came up with the following stackoverflow post:
 // https://stackoverflow.com/questions/9507184/can-openssl-on-windows-use-the-system-certificate-store
 inline bool load_system_certs_on_windows(X509_STORE *store) {
@@ -6335,6 +6340,7 @@ inline bool load_system_certs_on_windows(X509_STORE *store) {
 
   return result;
 }
+#endif // CPPHTTPLIB_DISABLE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE
 #elif defined(CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN) && TARGET_OS_MAC
 template <typename T>
 using CFObjectPtr =
@@ -11343,8 +11349,10 @@ inline bool SSLClient::load_certs() {
     } else {
       auto loaded = false;
 #ifdef _WIN32
+#ifdef CPPHTTPLIB_DISABLE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE
       loaded =
           detail::load_system_certs_on_windows(SSL_CTX_get_cert_store(ctx_));
+#endif // CPPHTTPLIB_DISABLE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE
 #elif defined(CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN) && TARGET_OS_MAC
       loaded = detail::load_system_certs_on_macos(SSL_CTX_get_cert_store(ctx_));
 #endif // _WIN32
@@ -11391,6 +11399,8 @@ inline bool SSLClient::initialize_ssl(Socket &socket, Error &error) {
           }
 
           if (verification_status == SSLVerifierResponse::NoDecisionMade) {
+#if !defined(_WIN32) ||                                                        \
+    defined(CPPHTTPLIB_DISABLE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE)
             verify_result_ = SSL_get_verify_result(ssl2);
 
             if (verify_result_ != X509_V_OK) {
@@ -11399,6 +11409,8 @@ inline bool SSLClient::initialize_ssl(Socket &socket, Error &error) {
               output_error_log(error, nullptr);
               return false;
             }
+#endif // not _WIN32 ||
+       // CPPHTTPLIB_DISABLE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE
 
             auto server_cert = SSL_get1_peer_certificate(ssl2);
             auto se = detail::scope_exit([&] { X509_free(server_cert); });
@@ -11410,6 +11422,8 @@ inline bool SSLClient::initialize_ssl(Socket &socket, Error &error) {
               return false;
             }
 
+#if !defined(_WIN32) ||                                                        \
+    defined(CPPHTTPLIB_DISABLE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE)
             if (server_hostname_verification_) {
               if (!verify_host(server_cert)) {
                 last_openssl_error_ = X509_V_ERR_HOSTNAME_MISMATCH;
@@ -11418,6 +11432,87 @@ inline bool SSLClient::initialize_ssl(Socket &socket, Error &error) {
                 return false;
               }
             }
+#else  // _WIN32 && !
+       // CPPHTTPLIB_DISABLE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE Convert
+       // OpenSSL certificate to DER format
+            auto der_cert =
+                std::vector<unsigned char>(i2d_X509(server_cert, nullptr));
+            auto der_cert_data = der_cert.data();
+            if (i2d_X509(server_cert, &der_cert_data) < 0) {
+              error = Error::SSLServerVerification;
+              return false;
+            }
+
+            // Create a certificate context from the DER-encoded certificate
+            auto cert_context = CertCreateCertificateContext(
+                X509_ASN_ENCODING | PKCS_7_ASN_ENCODING, der_cert.data(),
+                static_cast<DWORD>(der_cert.size()));
+
+            if (cert_context == nullptr) {
+              error = Error::SSLServerVerification;
+              return false;
+            }
+
+            auto chain_para = CERT_CHAIN_PARA{};
+            chain_para.cbSize = sizeof(chain_para);
+            chain_para.dwUrlRetrievalTimeout = 10 * 1000;
+
+            auto chain_context = PCCERT_CHAIN_CONTEXT{};
+            auto result = CertGetCertificateChain(
+                nullptr, cert_context, nullptr, cert_context->hCertStore,
+                &chain_para,
+                CERT_CHAIN_CACHE_END_CERT |
+                    CERT_CHAIN_REVOCATION_CHECK_END_CERT |
+                    CERT_CHAIN_REVOCATION_ACCUMULATIVE_TIMEOUT,
+                nullptr, &chain_context);
+
+            CertFreeCertificateContext(cert_context);
+
+            if (!result || chain_context == nullptr) {
+              error = Error::SSLServerVerification;
+              return false;
+            }
+
+            // Verify chain policy
+            auto extra_policy_para = SSL_EXTRA_CERT_CHAIN_POLICY_PARA{};
+            extra_policy_para.cbSize = sizeof(extra_policy_para);
+            extra_policy_para.dwAuthType = AUTHTYPE_SERVER;
+            auto whost = detail::u8string_to_wstring(host_.c_str());
+            if (server_hostname_verification_) {
+              extra_policy_para.pwszServerName =
+                  const_cast<wchar_t *>(whost.c_str());
+            }
+
+            auto policy_para = CERT_CHAIN_POLICY_PARA{};
+            policy_para.cbSize = sizeof(policy_para);
+            policy_para.dwFlags =
+                CERT_CHAIN_POLICY_IGNORE_ALL_REV_UNKNOWN_FLAGS;
+            policy_para.pvExtraPolicyPara = &extra_policy_para;
+
+            auto policy_status = CERT_CHAIN_POLICY_STATUS{};
+            policy_status.cbSize = sizeof(policy_status);
+
+            result = CertVerifyCertificateChainPolicy(
+                CERT_CHAIN_POLICY_SSL, chain_context, &policy_para,
+                &policy_status);
+
+            CertFreeCertificateChain(chain_context);
+
+            if (!result) {
+              error = Error::SSLServerVerification;
+              return false;
+            }
+
+            if (policy_status.dwError != 0) {
+              if (policy_status.dwError == CERT_E_CN_NO_MATCH) {
+                error = Error::SSLServerHostnameVerification;
+              } else {
+                error = Error::SSLServerVerification;
+              }
+              return false;
+            }
+#endif // not _WIN32 ||
+       // CPPHTTPLIB_DISABLE_WINDOWS_AUTOMATIC_ROOT_CERTIFICATES_UPDATE
           }
         }