[PATCH v3 1/2] http: add client cert for HTTPS proxies.

["Jorge Lopez Silva via GitGitGadget" <gitgitgadget@gmail.com>]

From: Jorge Lopez Silva <jalopezsilva@gmail.com>

Git currently supports performing connections to HTTPS proxies but we
don't support doing mutual authentication with them (through TLS). This
commit adds the necessary options to be able to send a client
certificate to the HTTPS proxy.

A client certificate can provide an alternative way of authentication
instead of using 'ProxyAuthorization' or other more common methods of
authentication.  Libcurl supports this functionality already so changes
are somewhat minimal. The feature is guarded by the first available
libcurl version that supports these options.

4 configuration options are added and documented, cert, key, cert
password protected and CA info. The CA info should be used to specify a
different CA path to validate the HTTPS proxy cert.

Signed-off-by: Jorge Lopez Silva <jalopezsilva@gmail.com>
---
 Documentation/config/http.txt | 17 +++++++++
 http.c                        | 67 ++++++++++++++++++++++++++++++++---
 2 files changed, 79 insertions(+), 5 deletions(-)

diff --git a/Documentation/config/http.txt b/Documentation/config/http.txt
index e806033aab8..7d398f9afba 100644
--- a/Documentation/config/http.txt
+++ b/Documentation/config/http.txt
@@ -29,6 +29,23 @@ http.proxyAuthMethod::
 * `ntlm` - NTLM authentication (compare the --ntlm option of `curl(1)`)
 --
 
+http.proxySSLCert::
+	The pathname of a file that stores a client certificate to use to authenticate
+	with an HTTPS proxy.
+
+http.proxySSLKey::
+	The pathname of a file that stores a private key to use to authenticate with
+	an HTTPS proxy.
+
+http.proxySSLCertPasswordProtected::
+	Enable Git's password prompt for the proxy SSL certificate.  Otherwise OpenSSL
+	will prompt the user, possibly many times, if the certificate or private key
+	is encrypted.
+
+http.proxySSLCAInfo::
+	Pathname to the file containing the certificate bundle that should be used to
+	verify the proxy with when using an HTTPS proxy.
+
 http.emptyAuth::
 	Attempt authentication without seeking a username or password.  This
 	can be used to attempt GSS-Negotiate authentication without specifying
diff --git a/http.c b/http.c
index 00a0e507633..8d616b5d60e 100644
--- a/http.c
+++ b/http.c
@@ -86,6 +86,13 @@ static long curl_low_speed_time = -1;
 static int curl_ftp_no_epsv;
 static const char *curl_http_proxy;
 static const char *http_proxy_authmethod;
+
+static const char *http_proxy_ssl_cert;
+static const char *http_proxy_ssl_key;
+static const char *http_proxy_ssl_ca_info;
+static struct credential proxy_cert_auth = CREDENTIAL_INIT;
+static int proxy_ssl_cert_password_required;
+
 static struct {
 	const char *name;
 	long curlauth_param;
@@ -365,6 +372,20 @@ static int http_options(const char *var, const char *value, void *cb)
 	if (!strcmp("http.proxyauthmethod", var))
 		return git_config_string(&http_proxy_authmethod, var, value);
 
+	if (!strcmp("http.proxysslcert", var))
+		return git_config_string(&http_proxy_ssl_cert, var, value);
+
+	if (!strcmp("http.proxysslkey", var))
+		return git_config_string(&http_proxy_ssl_key, var, value);
+
+	if (!strcmp("http.proxysslcainfo", var))
+		return git_config_string(&http_proxy_ssl_ca_info, var, value);
+
+	if (!strcmp("http.proxysslcertpasswordprotected", var)) {
+		proxy_ssl_cert_password_required = git_config_bool(var, value);
+		return 0;
+	}
+
 	if (!strcmp("http.cookiefile", var))
 		return git_config_pathname(&curl_cookie_file, var, value);
 	if (!strcmp("http.savecookies", var)) {
@@ -565,6 +586,21 @@ static int has_cert_password(void)
 	return 1;
 }
 
+#if LIBCURL_VERSION_NUM >= 0x073400
+static int has_proxy_cert_password(void)
+{
+	if (http_proxy_ssl_cert == NULL || proxy_ssl_cert_password_required != 1)
+		return 0;
+	if (!proxy_cert_auth.password) {
+		proxy_cert_auth.protocol = xstrdup("cert");
+		proxy_cert_auth.username = xstrdup("");
+		proxy_cert_auth.path = xstrdup(http_proxy_ssl_cert);
+		credential_fill(&proxy_cert_auth);
+	}
+	return 1;
+}
+#endif
+
 #if LIBCURL_VERSION_NUM >= 0x071900
 static void set_curl_keepalive(CURL *c)
 {
@@ -924,8 +960,14 @@ static CURL *get_curl_handle(void)
 #if LIBCURL_VERSION_NUM >= 0x073400
 		curl_easy_setopt(result, CURLOPT_PROXY_CAINFO, NULL);
 #endif
-	} else if (ssl_cainfo != NULL)
-		curl_easy_setopt(result, CURLOPT_CAINFO, ssl_cainfo);
+	} else if (ssl_cainfo != NULL || http_proxy_ssl_ca_info != NULL) {
+		if (ssl_cainfo != NULL)
+			curl_easy_setopt(result, CURLOPT_CAINFO, ssl_cainfo);
+#if LIBCURL_VERSION_NUM >= 0x073400
+		if (http_proxy_ssl_ca_info != NULL)
+			curl_easy_setopt(result, CURLOPT_PROXY_CAINFO, http_proxy_ssl_ca_info);
+#endif
+	}
 
 	if (curl_low_speed_limit > 0 && curl_low_speed_time > 0) {
 		curl_easy_setopt(result, CURLOPT_LOW_SPEED_LIMIT,
@@ -1018,9 +1060,18 @@ static CURL *get_curl_handle(void)
 				CURLOPT_PROXYTYPE, CURLPROXY_SOCKS4);
 #endif
 #if LIBCURL_VERSION_NUM >= 0x073400
-		else if (starts_with(curl_http_proxy, "https"))
-			curl_easy_setopt(result,
-				CURLOPT_PROXYTYPE, CURLPROXY_HTTPS);
+		else if (starts_with(curl_http_proxy, "https")) {
+			curl_easy_setopt(result, CURLOPT_PROXYTYPE, CURLPROXY_HTTPS);
+
+			if (http_proxy_ssl_cert)
+				curl_easy_setopt(result, CURLOPT_PROXY_SSLCERT, http_proxy_ssl_cert);
+
+			if (http_proxy_ssl_key)
+				curl_easy_setopt(result, CURLOPT_PROXY_SSLKEY, http_proxy_ssl_key);
+
+			if (has_proxy_cert_password())
+				curl_easy_setopt(result, CURLOPT_PROXY_KEYPASSWD, proxy_cert_auth.password);
+		}
 #endif
 		if (strstr(curl_http_proxy, "://"))
 			credential_from_url(&proxy_auth, curl_http_proxy);
@@ -1230,6 +1281,12 @@ void http_cleanup(void)
 	}
 	ssl_cert_password_required = 0;
 
+	if (proxy_cert_auth.password != NULL) {
+		memset(proxy_cert_auth.password, 0, strlen(proxy_cert_auth.password));
+		FREE_AND_NULL(proxy_cert_auth.password);
+	}
+	proxy_ssl_cert_password_required = 0;
+
 	FREE_AND_NULL(cached_accept_language);
 }
 
-- 
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