Merge pull request git-for-windows#3293 from pascalmuller/http-support-automatically-sending-client-certificate

http: Add support for enabling automatic sending of SSL client certificate

Author: dscho

Documentation/config/http.txt

@@ -205,6 +205,11 @@ http.schannelUseSSLCAInfo::
 	when the `schannel` backend was configured via `http.sslBackend`,
 	unless `http.schannelUseSSLCAInfo` overrides this behavior.
 
+http.sslAutoClientCert::
+	As of cURL v7.77.0, the Secure Channel backend won't automatically
+	send client certificates from the Windows Certificate Store anymore.
+	To opt in to the old behavior, http.sslAutoClientCert can be set.
+
 http.pinnedPubkey::
 	Public key of the https service. It may either be the filename of
 	a PEM or DER encoded public key file or a string starting with

git-curl-compat.h

@@ -134,4 +134,12 @@
 #define GIT_CURL_HAVE_CURLOPT_PROTOCOLS_STR 1
 #endif
 
+/*
+ * CURLSSLOPT_AUTO_CLIENT_CERT was added in 7.77.0, released in May
+ * 2021.
+ */
+#if LIBCURL_VERSION_NUM >= 0x074d00
+#define GIT_CURL_HAVE_CURLSSLOPT_AUTO_CLIENT_CERT
+#endif
+
 #endif

http.c

@@ -150,6 +150,8 @@ static int http_schannel_check_revoke_mode =
  */
 static int http_schannel_use_ssl_cainfo;
 
+static int http_auto_client_cert;
+
 size_t fread_buffer(char *ptr, size_t eltsize, size_t nmemb, void *buffer_)
 {
 	size_t size = eltsize * nmemb;
@@ -312,6 +314,11 @@ static int http_options(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
+	if (!strcmp("http.sslautoclientcert", var)) {
+		http_auto_client_cert = git_config_bool(var, value);
+		return 0;
+	}
+
 	if (!strcmp("http.minsessions", var)) {
 		min_curl_sessions = git_config_int(var, value);
 		if (min_curl_sessions > 1)
@@ -886,13 +893,24 @@ static CURL *get_curl_handle(void)
 	}
 #endif
 
-	if (http_ssl_backend && !strcmp("schannel", http_ssl_backend) &&
-	    http_schannel_check_revoke_mode) {
+	if (http_ssl_backend && !strcmp("schannel", http_ssl_backend)) {
+		long ssl_options = 0;
+		if (http_schannel_check_revoke_mode) {
 #ifdef GIT_CURL_HAVE_CURLSSLOPT_NO_REVOKE
-		curl_easy_setopt(result, CURLOPT_SSL_OPTIONS, http_schannel_check_revoke_mode);
+			ssl_options |= http_schannel_check_revoke_mode;
 #else
-		warning(_("CURLSSLOPT_NO_REVOKE not supported with cURL < 7.44.0"));
+			warning(_("CURLSSLOPT_NO_REVOKE not supported with cURL < 7.44.0"));
 #endif
+		}
+
+		if (http_auto_client_cert) {
+#ifdef GIT_CURL_HAVE_CURLSSLOPT_AUTO_CLIENT_CERT
+			ssl_options |= CURLSSLOPT_AUTO_CLIENT_CERT;
+#endif
+		}
+
+		if (ssl_options)
+			curl_easy_setopt(result, CURLOPT_SSL_OPTIONS, ssl_options);
 	}
 
 	if (http_proactive_auth)