http: maintain authentication across connections

For request-based authentication mechanisms (Basic, Digest) we should
keep the authentication context alive across socket connections, since
the authentication headers must be transmitted with every request.

However, we should continue to remove authentication contexts for
mechanisms with connection affinity (NTLM, Negotiate) since we need to
reauthenticate for every socket connection.

src/transports/http.c

@@ -81,7 +81,8 @@ typedef struct {
 	git_credtype_t credtypes;
 
 	git_cred *cred;
-	unsigned url_cred_presented : 1;
+	unsigned url_cred_presented : 1,
+	    authenticated : 1;
 
 	git_vector auth_challenges;
 	git_http_auth_context *auth_context;
@@ -501,6 +502,12 @@ static int on_auth_required(
 	return 0;
 }
 
+static void on_auth_success(http_server *server)
+{
+	server->url_cred_presented = 0;
+	server->authenticated = 1;
+}
+
 static int on_headers_complete(http_parser *parser)
 {
 	parser_context *ctx = (parser_context *) parser->data;
@@ -549,6 +556,8 @@ static int on_headers_complete(http_parser *parser)
 		    SERVER_TYPE_PROXY,
 		    t->proxy_opts.credentials,
 		    t->proxy_opts.payload);
+	else
+		on_auth_success(&t->proxy);
 
 	/* Check for an authentication failure. */
 	if (parser->status_code == 401 && get_verb == s->verb)
@@ -559,6 +568,8 @@ static int on_headers_complete(http_parser *parser)
 		    SERVER_TYPE_REMOTE,
 		    t->owner->cred_acquire_cb,
 		    t->owner->cred_acquire_payload);
+	else
+		on_auth_success(&t->server);
 
 	/* Check for a redirect.
 	 * Right now we only permit a redirect to the same hostname. */
@@ -988,6 +999,29 @@ done:
 	return error;
 }
 
+static void reset_auth_connection(http_server *server)
+{
+	/*
+	 * If we've authenticated and we're doing "normal"
+	 * authentication with a request affinity (Basic, Digest)
+	 * then we want to _keep_ our context, since authentication
+	 * survives even through non-keep-alive connections.  If
+	 * we've authenticated and we're doing connection-based
+	 * authentication (NTLM, Negotiate) - indicated by the presence
+	 * of an `is_complete` callback - then we need to restart
+	 * authentication on a new connection.
+	 */
+
+	if (server->authenticated &&
+	    server->auth_context &&
+	    server->auth_context->is_complete) {
+		free_auth_context(server);
+
+		server->url_cred_presented = 0;
+		server->authenticated = 0;
+	}
+}
+
 static int http_connect(http_subtransport *t)
 {
 	git_net_url *url;
@@ -1014,13 +1048,11 @@ static int http_connect(http_subtransport *t)
 		t->proxy.stream = NULL;
 	}
 
-	free_auth_context(&t->server);
-	free_auth_context(&t->proxy);
-
-	t->server.url_cred_presented = false;
-	t->proxy.url_cred_presented = false;
+	reset_auth_connection(&t->server);
+	reset_auth_connection(&t->proxy);
 
 	t->connected = 0;
+	t->keepalive = 0;
 
 	if (t->proxy_opts.type == GIT_PROXY_SPECIFIED) {
 		url = &t->proxy.url;