From 39551406539e6ea87f89f619f7f0800e887e9b57 Mon Sep 17 00:00:00 2001
From: Kim Altintop <kim@eagain.st>
Date: Fri, 13 Aug 2021 06:23:50 +0000
Subject: [PATCH] upload-pack.c: treat want-ref relative to namespace

When 'upload-pack' runs within the context of a git namespace, treat any
'want-ref' lines the client sends as relative to that namespace.

Also check if the wanted ref is hidden via 'hideRefs'. If it is hidden,
respond with an error as if the ref didn't exist.

Helped-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Kim Altintop <kim@eagain.st>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 t/t5703-upload-pack-ref-in-want.sh | 135 +++++++++++++++++++++++++++++
 upload-pack.c                      |  18 ++--
 2 files changed, 146 insertions(+), 7 deletions(-)

diff --git a/t/t5703-upload-pack-ref-in-want.sh b/t/t5703-upload-pack-ref-in-want.sh
index 3dad21ff45..220098523a 100755
--- a/t/t5703-upload-pack-ref-in-want.sh
+++ b/t/t5703-upload-pack-ref-in-want.sh
@@ -299,6 +299,141 @@ test_expect_success 'fetching with wildcard that matches multiple refs' '
 	grep "want-ref refs/heads/o/bar" log
 '
 
+REPO="$(pwd)/repo-ns"
+
+test_expect_success 'setup namespaced repo' '
+	(
+		git init -b main "$REPO" &&
+		cd "$REPO" &&
+		test_commit a &&
+		test_commit b &&
+		git checkout a &&
+		test_commit c &&
+		git checkout a &&
+		test_commit d &&
+		git update-ref refs/heads/ns-no b &&
+		git update-ref refs/namespaces/ns/refs/heads/ns-yes c &&
+		git update-ref refs/namespaces/ns/refs/heads/hidden d
+	) &&
+	git -C "$REPO" config uploadpack.allowRefInWant true
+'
+
+test_expect_success 'with namespace: want-ref is considered relative to namespace' '
+	wanted_ref=refs/heads/ns-yes &&
+
+	oid=$(git -C "$REPO" rev-parse "refs/namespaces/ns/$wanted_ref") &&
+	cat >expected_refs <<-EOF &&
+	$oid $wanted_ref
+	EOF
+	cat >expected_commits <<-EOF &&
+	$oid
+	$(git -C "$REPO" rev-parse a)
+	EOF
+
+	write_fetch_command >pkt <<-EOF &&
+	want-ref $wanted_ref
+	EOF
+	test-tool pkt-line pack <pkt >in &&
+
+	GIT_NAMESPACE=ns test-tool -C "$REPO" serve-v2 --stateless-rpc >out <in &&
+	check_output
+'
+
+test_expect_success 'with namespace: want-ref outside namespace is unknown' '
+	wanted_ref=refs/heads/ns-no &&
+
+	write_fetch_command >pkt <<-EOF &&
+	want-ref $wanted_ref
+	EOF
+	test-tool pkt-line pack <pkt >in &&
+
+	test_must_fail env GIT_NAMESPACE=ns \
+		test-tool -C "$REPO" serve-v2 --stateless-rpc >out <in &&
+	grep "unknown ref" out
+'
+
+# Cross-check refs/heads/ns-no indeed exists
+test_expect_success 'without namespace: want-ref outside namespace succeeds' '
+	wanted_ref=refs/heads/ns-no &&
+
+	oid=$(git -C "$REPO" rev-parse $wanted_ref) &&
+	cat >expected_refs <<-EOF &&
+	$oid $wanted_ref
+	EOF
+	cat >expected_commits <<-EOF &&
+	$oid
+	$(git -C "$REPO" rev-parse a)
+	EOF
+
+	write_fetch_command >pkt <<-EOF &&
+	want-ref $wanted_ref
+	EOF
+	test-tool pkt-line pack <pkt >in &&
+
+	test-tool -C "$REPO" serve-v2 --stateless-rpc >out <in &&
+	check_output
+'
+
+test_expect_success 'with namespace: hideRefs is matched, relative to namespace' '
+	wanted_ref=refs/heads/hidden &&
+	git -C "$REPO" config transfer.hideRefs $wanted_ref &&
+
+	write_fetch_command >pkt <<-EOF &&
+	want-ref $wanted_ref
+	EOF
+	test-tool pkt-line pack <pkt >in &&
+
+	test_must_fail env GIT_NAMESPACE=ns \
+		test-tool -C "$REPO" serve-v2 --stateless-rpc >out <in &&
+	grep "unknown ref" out
+'
+
+# Cross-check refs/heads/hidden indeed exists
+test_expect_success 'with namespace: want-ref succeeds if hideRefs is removed' '
+	wanted_ref=refs/heads/hidden &&
+	git -C "$REPO" config --unset transfer.hideRefs $wanted_ref &&
+
+	oid=$(git -C "$REPO" rev-parse "refs/namespaces/ns/$wanted_ref") &&
+	cat >expected_refs <<-EOF &&
+	$oid $wanted_ref
+	EOF
+	cat >expected_commits <<-EOF &&
+	$oid
+	$(git -C "$REPO" rev-parse a)
+	EOF
+
+	write_fetch_command >pkt <<-EOF &&
+	want-ref $wanted_ref
+	EOF
+	test-tool pkt-line pack <pkt >in &&
+
+	GIT_NAMESPACE=ns test-tool -C "$REPO" serve-v2 --stateless-rpc >out <in &&
+	check_output
+'
+
+test_expect_success 'without namespace: relative hideRefs does not match' '
+	wanted_ref=refs/namespaces/ns/refs/heads/hidden &&
+	git -C "$REPO" config transfer.hideRefs refs/heads/hidden &&
+
+	oid=$(git -C "$REPO" rev-parse $wanted_ref) &&
+	cat >expected_refs <<-EOF &&
+	$oid $wanted_ref
+	EOF
+	cat >expected_commits <<-EOF &&
+	$oid
+	$(git -C "$REPO" rev-parse a)
+	EOF
+
+	write_fetch_command >pkt <<-EOF &&
+	want-ref $wanted_ref
+	EOF
+	test-tool pkt-line pack <pkt >in &&
+
+	test-tool -C "$REPO" serve-v2 --stateless-rpc >out <in &&
+	check_output
+'
+
+
 . "$TEST_DIRECTORY"/lib-httpd.sh
 start_httpd
 
diff --git a/upload-pack.c b/upload-pack.c
index 297b76fcb4..6ce07231d3 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -1417,21 +1417,25 @@ static int parse_want_ref(struct packet_writer *writer, const char *line,
 			  struct string_list *wanted_refs,
 			  struct object_array *want_obj)
 {
-	const char *arg;
-	if (skip_prefix(line, "want-ref ", &arg)) {
+	const char *refname_nons;
+	if (skip_prefix(line, "want-ref ", &refname_nons)) {
 		struct object_id oid;
 		struct string_list_item *item;
 		struct object *o;
+		struct strbuf refname = STRBUF_INIT;
 
-		if (read_ref(arg, &oid)) {
-			packet_writer_error(writer, "unknown ref %s", arg);
-			die("unknown ref %s", arg);
+		strbuf_addf(&refname, "%s%s", get_git_namespace(), refname_nons);
+		if (ref_is_hidden(refname_nons, refname.buf) ||
+		    read_ref(refname.buf, &oid)) {
+			packet_writer_error(writer, "unknown ref %s", refname_nons);
+			die("unknown ref %s", refname_nons);
 		}
+		strbuf_release(&refname);
 
-		item = string_list_append(wanted_refs, arg);
+		item = string_list_append(wanted_refs, refname_nons);
 		item->util = oiddup(&oid);
 
-		o = parse_object_or_die(&oid, arg);
+		o = parse_object_or_die(&oid, refname_nons);
 		if (!(o->flags & WANTED)) {
 			o->flags |= WANTED;
 			add_object_array(o, NULL, want_obj);