Subject: [PATCH v2 7/9] connect: tell server that the client understands v1

From: Brandon Williams <[email-masked]>
Date: Tue, 26 Sep 2017 16:56:25 -0700

Teach the connection logic to tell a serve that it understands protocol
v1.  This is done in 2 different ways for the built in protocols.

1. git://
   A normal request is structured as "command path/to/repo\0host=..\0"
   and due to a bug in an old version of git-daemon 73bb33a94 (daemon:
   Strictly parse the "extra arg" part of the command, 2009-06-04) we
   aren't able to place any extra args (separated by NULs) besides the
   host.  In order to get around this limitation put protocol version
   information after a second NUL byte so the request is structured
   like: "command path/to/repo\0host=..\0\0version=1\0".  git-daemon can
   then parse out the version number and set GIT_PROTOCOL.

2. ssh://, file://
   Set GIT_PROTOCOL envvar with the desired protocol version.  The
   envvar can be sent across ssh by using '-o SendEnv=GIT_PROTOCOL' and
   having the server whitelist this envvar.

Signed-off-by: Brandon Williams <[email-masked]>
---
 connect.c              |  37 ++++++--
 t/t5700-protocol-v1.sh | 223 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 255 insertions(+), 5 deletions(-)
 create mode 100755 t/t5700-protocol-v1.sh

diff --git a/connect.c b/connect.c
index 1805debf3..12ebab724 100644
--- a/connect.c
+++ b/connect.c
@@ -871,6 +871,7 @@ struct child_process *git_connect(int fd[2], const char *url,
 		printf("Diag: path=%s\n", path ? path : "NULL");
 		conn = NULL;
 	} else if (protocol == PROTO_GIT) {
+		struct strbuf request = STRBUF_INIT;
 		/*
 		 * Set up virtual host information based on where we will
 		 * connect, unless the user has overridden us in
@@ -898,13 +899,25 @@ struct child_process *git_connect(int fd[2], const char *url,
 		 * Note: Do not add any other headers here!  Doing so
 		 * will cause older git-daemon servers to crash.
 		 */
-		packet_write_fmt(fd[1],
-			     "%s %s%chost=%s%c",
-			     prog, path, 0,
-			     target_host, 0);
+		strbuf_addf(&request,
+			    "%s %s%chost=%s%c",
+			    prog, path, 0,
+			    target_host, 0);
+
+		/* If using a new version put that stuff here after a second null byte */
+		if (get_protocol_version_config() > 0) {
+			strbuf_addch(&request, '\0');
+			strbuf_addf(&request, "version=%d%c",
+				    get_protocol_version_config(), '\0');
+		}
+
+		packet_write(fd[1], request.buf, request.len);
+
 		free(target_host);
+		strbuf_release(&request);
 	} else {
 		struct strbuf cmd = STRBUF_INIT;
+		const char *const *var;
 
 		conn = xmalloc(sizeof(*conn));
 		child_process_init(conn);
@@ -917,7 +930,9 @@ struct child_process *git_connect(int fd[2], const char *url,
 		sq_quote_buf(&cmd, path);
 
 		/* remove repo-local variables from the environment */
-		conn->env = local_repo_env;
+		for (var = local_repo_env; *var; var++)
+			argv_array_push(&conn->env_array, *var);
+
 		conn->use_shell = 1;
 		conn->in = conn->out = -1;
 		if (protocol == PROTO_SSH) {
@@ -971,6 +986,14 @@ struct child_process *git_connect(int fd[2], const char *url,
 			}
 
 			argv_array_push(&conn->args, ssh);
+
+			if (get_protocol_version_config() > 0) {
+				argv_array_push(&conn->args, "-o");
+				argv_array_push(&conn->args, "SendEnv=" GIT_PROTOCOL_ENVIRONMENT);
+				argv_array_pushf(&conn->env_array, GIT_PROTOCOL_ENVIRONMENT "=version=%d",
+						 get_protocol_version_config());
+			}
+
 			if (flags & CONNECT_IPV4)
 				argv_array_push(&conn->args, "-4");
 			else if (flags & CONNECT_IPV6)
@@ -985,6 +1008,10 @@ struct child_process *git_connect(int fd[2], const char *url,
 			argv_array_push(&conn->args, ssh_host);
 		} else {
 			transport_check_allowed("file");
+			if (get_protocol_version_config() > 0) {
+				argv_array_pushf(&conn->env_array, GIT_PROTOCOL_ENVIRONMENT "=version=%d",
+						 get_protocol_version_config());
+			}
 		}
 		argv_array_push(&conn->args, cmd.buf);
 
diff --git a/t/t5700-protocol-v1.sh b/t/t5700-protocol-v1.sh
new file mode 100755
index 000000000..1988bbce6
--- /dev/null
+++ b/t/t5700-protocol-v1.sh
@@ -0,0 +1,223 @@
+#!/bin/sh
+
+test_description='test git wire-protocol transition'
+
+TEST_NO_CREATE_REPO=1
+
+. ./test-lib.sh
+
+# Test protocol v1 with 'git://' transport
+#
+. "$TEST_DIRECTORY"/lib-git-daemon.sh
+start_git_daemon --export-all --enable=receive-pack
+daemon_parent=$GIT_DAEMON_DOCUMENT_ROOT_PATH/parent
+
+test_expect_success 'create repo to be served by git-daemon' '
+	git init "$daemon_parent" &&
+	test_commit -C "$daemon_parent" one
+'
+
+test_expect_success 'clone with git:// using protocol v1' '
+	GIT_TRACE_PACKET=1 git -c protocol.version=1 \
+		clone "$GIT_DAEMON_URL/parent" daemon_child 2>log &&
+
+	git -C daemon_child log -1 --format=%s >actual &&
+	git -C "$daemon_parent" log -1 --format=%s >expect &&
+	test_cmp expect actual &&
+
+	# Client requested to use protocol v1
+	grep "version=1" log &&
+	# Server responded using protocol v1
+	grep "clone< version 1" log
+'
+
+test_expect_success 'fetch with git:// using protocol v1' '
+	test_commit -C "$daemon_parent" two &&
+
+	GIT_TRACE_PACKET=1 git -C daemon_child -c protocol.version=1 \
+		fetch 2>log &&
+
+	git -C daemon_child log -1 --format=%s FETCH_HEAD >actual &&
+	git -C "$daemon_parent" log -1 --format=%s >expect &&
+	test_cmp expect actual &&
+
+	# Client requested to use protocol v1
+	grep "version=1" log &&
+	# Server responded using protocol v1
+	grep "fetch< version 1" log
+'
+
+test_expect_success 'pull with git:// using protocol v1' '
+	GIT_TRACE_PACKET=1 git -C daemon_child -c protocol.version=1 \
+		pull 2>log &&
+
+	git -C daemon_child log -1 --format=%s >actual &&
+	git -C "$daemon_parent" log -1 --format=%s >expect &&
+	test_cmp expect actual &&
+
+	# Client requested to use protocol v1
+	grep "version=1" log &&
+	# Server responded using protocol v1
+	grep "fetch< version 1" log
+'
+
+test_expect_success 'push with git:// using protocol v1' '
+	test_commit -C daemon_child three &&
+
+	# Since the repository being served isnt bare we need to push to
+	# another branch explicitly to avoid mangling the master branch
+	GIT_TRACE_PACKET=1 git -C daemon_child -c protocol.version=1 \
+		push origin HEAD:client_branch 2>log &&
+
+	git -C daemon_child log -1 --format=%s >actual &&
+	git -C "$daemon_parent" log -1 --format=%s client_branch >expect &&
+	test_cmp expect actual &&
+
+	# Client requested to use protocol v1
+	grep "version=1" log &&
+	# Server responded using protocol v1
+	grep "push< version 1" log
+'
+
+stop_git_daemon
+
+# Test protocol v1 with 'file://' transport
+#
+test_expect_success 'create repo to be served by file:// transport' '
+	git init file_parent &&
+	test_commit -C file_parent one
+'
+
+test_expect_success 'clone with file:// using protocol v1' '
+	GIT_TRACE_PACKET=1 git -c protocol.version=1 \
+		clone "file://$(pwd)/file_parent" file_child 2>log &&
+
+	git -C file_child log -1 --format=%s >actual &&
+	git -C file_parent log -1 --format=%s >expect &&
+	test_cmp expect actual &&
+
+	# Server responded using protocol v1
+	grep "clone< version 1" log
+'
+
+test_expect_success 'fetch with file:// using protocol v1' '
+	test_commit -C file_parent two &&
+
+	GIT_TRACE_PACKET=1 git -C file_child -c protocol.version=1 \
+		fetch 2>log &&
+
+	git -C file_child log -1 --format=%s FETCH_HEAD >actual &&
+	git -C file_parent log -1 --format=%s >expect &&
+	test_cmp expect actual &&
+
+	# Server responded using protocol v1
+	grep "fetch< version 1" log
+'
+
+test_expect_success 'pull with file:// using protocol v1' '
+	GIT_TRACE_PACKET=1 git -C file_child -c protocol.version=1 \
+		pull 2>log &&
+
+	git -C file_child log -1 --format=%s >actual &&
+	git -C file_parent log -1 --format=%s >expect &&
+	test_cmp expect actual &&
+
+	# Server responded using protocol v1
+	grep "fetch< version 1" log
+'
+
+test_expect_success 'push with file:// using protocol v1' '
+	test_commit -C file_child three &&
+
+	# Since the repository being served isnt bare we need to push to
+	# another branch explicitly to avoid mangling the master branch
+	GIT_TRACE_PACKET=1 git -C file_child -c protocol.version=1 \
+		push origin HEAD:client_branch 2>log &&
+
+	git -C file_child log -1 --format=%s >actual &&
+	git -C file_parent log -1 --format=%s client_branch >expect &&
+	test_cmp expect actual &&
+
+	# Server responded using protocol v1
+	grep "push< version 1" log
+'
+
+# Test protocol v1 with 'ssh://' transport
+#
+test_expect_success 'setup ssh wrapper' '
+	GIT_SSH="$GIT_BUILD_DIR/t/helper/test-fake-ssh$X" &&
+	export GIT_SSH &&
+	export TRASH_DIRECTORY &&
+	>"$TRASH_DIRECTORY"/ssh-output
+'
+
+expect_ssh () {
+	test_when_finished '(cd "$TRASH_DIRECTORY" && rm -f ssh-expect && >ssh-output)' &&
+	echo "ssh: -o SendEnv=GIT_PROTOCOL myhost $1 '$PWD/ssh_parent'" >"$TRASH_DIRECTORY/ssh-expect" &&
+	(cd "$TRASH_DIRECTORY" && test_cmp ssh-expect ssh-output)
+}
+
+test_expect_success 'create repo to be served by ssh:// transport' '
+	git init ssh_parent &&
+	test_commit -C ssh_parent one
+'
+
+test_expect_success 'clone with ssh:// using protocol v1' '
+	GIT_TRACE_PACKET=1 git -c protocol.version=1 \
+		clone "ssh://myhost:$(pwd)/ssh_parent" ssh_child 2>log &&
+	expect_ssh git-upload-pack &&
+
+	git -C ssh_child log -1 --format=%s >actual &&
+	git -C ssh_parent log -1 --format=%s >expect &&
+	test_cmp expect actual &&
+
+	# Server responded using protocol v1
+	grep "clone< version 1" log
+'
+
+test_expect_success 'fetch with ssh:// using protocol v1' '
+	test_commit -C ssh_parent two &&
+
+	GIT_TRACE_PACKET=1 git -C ssh_child -c protocol.version=1 \
+		fetch 2>log &&
+	expect_ssh git-upload-pack &&
+
+	git -C ssh_child log -1 --format=%s FETCH_HEAD >actual &&
+	git -C ssh_parent log -1 --format=%s >expect &&
+	test_cmp expect actual &&
+
+	# Server responded using protocol v1
+	grep "fetch< version 1" log
+'
+
+test_expect_success 'pull with ssh:// using protocol v1' '
+	GIT_TRACE_PACKET=1 git -C ssh_child -c protocol.version=1 \
+		pull 2>log &&
+	expect_ssh git-upload-pack &&
+
+	git -C ssh_child log -1 --format=%s >actual &&
+	git -C ssh_parent log -1 --format=%s >expect &&
+	test_cmp expect actual &&
+
+	# Server responded using protocol v1
+	grep "fetch< version 1" log
+'
+
+test_expect_success 'push with ssh:// using protocol v1' '
+	test_commit -C ssh_child three &&
+
+	# Since the repository being served isnt bare we need to push to
+	# another branch explicitly to avoid mangling the master branch
+	GIT_TRACE_PACKET=1 git -C ssh_child -c protocol.version=1 \
+		push origin HEAD:client_branch 2>log &&
+	expect_ssh git-receive-pack &&
+
+	git -C ssh_child log -1 --format=%s >actual &&
+	git -C ssh_parent log -1 --format=%s client_branch >expect &&
+	test_cmp expect actual &&
+
+	# Server responded using protocol v1
+	grep "push< version 1" log
+'
+
+test_done
-- 
2.14.1.992.g2c7b836f3a-goog