credential-cache: respect request capabilities

Previously, credential-cache responded with capability[]=authtype
regardless of request.

The capabilities in a credential helper response should be a subset of
the capabilities in the request.

Author: hickford

builtin/credential-cache--daemon.c

@@ -134,17 +134,16 @@ static void serve_one_client(FILE *in, FILE *out)
 	else if (!strcmp(action.buf, "get")) {
 		struct credential_cache_entry *e = lookup_credential(&c);
 		if (e) {
-			e->item.capa_authtype.request_initial = 1;
-			e->item.capa_authtype.request_helper = 1;
-
-			fprintf(out, "capability[]=authtype\n");
+			if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_RESPONSE)) {
+				fprintf(out, "capability[]=authtype\n");
+			}
 			if (e->item.username)
 				fprintf(out, "username=%s\n", e->item.username);
 			if (e->item.password)
 				fprintf(out, "password=%s\n", e->item.password);
-			if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_HELPER) && e->item.authtype)
+			if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_RESPONSE) && e->item.authtype)
 				fprintf(out, "authtype=%s\n", e->item.authtype);
-			if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_HELPER) && e->item.credential)
+			if (credential_has_capability(&c.capa_authtype, CREDENTIAL_OP_RESPONSE) && e->item.credential)
 				fprintf(out, "credential=%s\n", e->item.credential);
 			if (e->item.password_expiry_utc != TIME_MAX)
 				fprintf(out, "password_expiry_utc=%"PRItime"\n",

t/lib-credential.sh

@@ -566,6 +566,21 @@ helper_test_authtype() {
 		EOF
 	'
 
+	test_expect_success "helper ($HELPER) does not get authtype and credential without authtype capability" '
+		check fill $HELPER <<-\EOF
+		protocol=https
+		host=git.example.com
+		--
+		protocol=https
+		host=git.example.com
+		username=askpass-username
+		password=askpass-password
+		--
+		askpass: Username for '\''https://git.example.com'\'':
+		askpass: Password for '\''https://[email protected]'\'':
+		EOF
+	'
+
 	test_expect_success "helper ($HELPER) stores authtype and credential with username" '
 		check approve $HELPER <<-\EOF
 		capability[]=authtype

t/t0303-credential-external.sh

@@ -63,6 +63,7 @@ helper_test_clean "$GIT_TEST_CREDENTIAL_HELPER"
 helper_test "$GIT_TEST_CREDENTIAL_HELPER"
 helper_test_password_expiry_utc "$GIT_TEST_CREDENTIAL_HELPER"
 helper_test_oauth_refresh_token "$GIT_TEST_CREDENTIAL_HELPER"
+helper_test_authtype "$GIT_TEST_CREDENTIAL_HELPER"
 
 if test -z "$GIT_TEST_CREDENTIAL_HELPER_TIMEOUT"; then
 	say "# skipping timeout tests (GIT_TEST_CREDENTIAL_HELPER_TIMEOUT not set)"