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connect: tell server that the client understands v1
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Teach the connection logic to tell a serve that it understands protocol
v1.  This is done in 2 different ways for the builtin transports, both
of which ultimately set 'GIT_PROTOCOL' to 'version=1' on the server.

1. git://
   A normal request to git-daemon is structured as
   "command path/to/repo\0host=..\0" and due to a bug introduced in
   49ba83f (Add virtualization support to git-daemon, 2006-09-19) we
   aren't able to place any extra arguments (separated by NULs) besides
   the host otherwise the parsing of those arguments would enter an
   infinite loop.  This bug was fixed in 73bb33a (daemon: Strictly
   parse the "extra arg" part of the command, 2009-06-04) but a check
   was put in place to disallow extra arguments so that new clients
   wouldn't trigger this bug in older servers.

   In order to get around this limitation git-daemon was taught to
   recognize additional request arguments hidden behind a second
   NUL byte.  Requests can then be structured like:
   "command path/to/repo\0host=..\0\0version=1\0key=value\0".
   git-daemon can then parse out the extra arguments and set
   'GIT_PROTOCOL' accordingly.

   By placing these extra arguments behind a second NUL byte we can
   skirt around both the infinite loop bug in 49ba83f (Add
   virtualization support to git-daemon, 2006-09-19) as well as the
   explicit disallowing of extra arguments introduced in 73bb33a
   (daemon: Strictly parse the "extra arg" part of the command,
   2009-06-04) because both of these versions of git-daemon check for a
   single NUL byte after the host argument before terminating the
   argument parsing.

2. ssh://, file://
   Set 'GIT_PROTOCOL' environment variable with the desired protocol
   version.  With the file:// transport, 'GIT_PROTOCOL' can be set
   explicitly in the locally running git-upload-pack or git-receive-pack
   processes.  With the ssh:// transport and OpenSSH compliant ssh
   programs, 'GIT_PROTOCOL' can be sent across ssh by using '-o
   SendEnv=GIT_PROTOCOL' and having the server whitelist this
   environment variable.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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@bmwill @gitster
bmwill authored and gitster committed Oct 17, 2017
1 parent 2609043 commit 0c2f0d2
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Showing 2 changed files with 255 additions and 5 deletions.
37 changes: 32 additions & 5 deletions connect.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -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);
Expand All @@ -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) {
Expand Down Expand Up @@ -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)
Expand All @@ -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);

Expand Down
223 changes: 223 additions & 0 deletions t/t5700-protocol-v1.sh
View file
Original file line number Diff line number Diff line change
@@ -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 "clone> .*\\\0\\\0version=1\\\0$" log &&
# Server responded using protocol v1
grep "clone< version 1" log
'

test_expect_success 'fetch with git:// using protocol v1' '
test_commit -C "$daemon_parent" two &&
GIT_TRACE_PACKET=1 git -C daemon_child -c protocol.version=1 \
fetch 2>log &&
git -C daemon_child log -1 --format=%s origin/master >actual &&
git -C "$daemon_parent" log -1 --format=%s >expect &&
test_cmp expect actual &&
# Client requested to use protocol v1
grep "fetch> .*\\\0\\\0version=1\\\0$" 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 "$daemon_parent" log -1 --format=%s >expect &&
test_cmp expect actual &&
# Client requested to use protocol v1
grep "fetch> .*\\\0\\\0version=1\\\0$" 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 &&
# Push to another branch, as the target repository has the
# master branch checked out and we cannot push into it.
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 "$daemon_parent" log -1 --format=%s client_branch >expect &&
test_cmp expect actual &&
# Client requested to use protocol v1
grep "push> .*\\\0\\\0version=1\\\0$" 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 origin/master >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 &&
# Push to another branch, as the target repository has the
# master branch checked out and we cannot push into it.
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="$GIT_BUILD_DIR/t/helper/test-fake-ssh" &&
export GIT_SSH &&
export TRASH_DIRECTORY &&
>"$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 origin/master >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 &&
# Push to another branch, as the target repository has the
# master branch checked out and we cannot push into it.
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

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