https://bugzilla.mindrot.org/show_bug.cgi?id=2529
Bug ID: 2529
Summary: direct-streamlocal channel open doesn't match PROTOCOL
documentation
Product: Portable OpenSSH
Version: -current
Hardware: All
OS: All
Status: NEW
Severity: normal
Priority: P5
Component: ssh
Assignee: [email protected]
Reporter: [email protected]
I attempted to implement support for [email protected]
channels in my own SSH implementation and found that the documentation
in the OpenSSH PROTOCOL file doesn't match the implementation in
OpenSSH. The PROTOCOL file describes the channel open message as:
byte SSH_MSG_CHANNEL_OPEN
string "[email protected]"
uint32 sender channel
uint32 initial window size
uint32 maximum packet size
string socket path
However, the implementation tacks some additional data to the end:
packet_start(SSH2_MSG_CHANNEL_OPEN);
packet_put_cstring(rtype);
packet_put_int(c->self);
packet_put_int(c->local_window_max);
packet_put_int(c->local_maxpacket);
if (strcmp(rtype, "direct-tcpip") == 0) {
/* target host, port */
packet_put_cstring(c->path);
packet_put_int(c->host_port);
} else if (strcmp(rtype,
"[email protected]") == 0) {
/* target path */
packet_put_cstring(c->path);
} else if (strcmp(rtype,
"[email protected]") == 0) {
/* listen path */
packet_put_cstring(c->path);
} else {
/* listen address, port */
packet_put_cstring(c->path);
packet_put_int(local_port);
}
if (strcmp(rtype, "[email protected]")
== 0) {
/* reserved for future owner/mode info */
packet_put_cstring("");
} else {
--> /* originator host and port */
--> packet_put_cstring(remote_ipaddr);
--> packet_put_int((u_int)remote_port);
}
packet_send();
It correctly special-cases forwarded-streamlocal, but for all other
cases (including direct-streamlocal) it appends the remote IP add and
port, even though these values are not applicable in the
direct-streamlocal case.
This may be difficult to fix in a backward-compatible manner, since the
code in serverloop.c actually seems to be expecting to get a host &
port:
target = packet_get_string(NULL);
originator = packet_get_string(NULL);
originator_port = packet_get_int();
packet_check_eom();
So, perhaps the right thing here is to update the documentation in
PROTOCOL to match the current implementation. It seems odd to send this
information when it looks like it will always be an empty string and a
port of zero, though, especially given that "port" information makes no
sense for this type of connection.
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