Difference between revisions of "Xbox Debug Monitor"

Revision as of 20:03, 22 May 2017

The Xbox Debug Monitor (XBDM) is a feature of Xbox Development Kits that provides remote debugging, file management, console discovery, and other services on TCP/UDP port 731. It is loaded by debug kernels at startup from C:\xbdm.dll and its configuration is read from E:\xbdm.ini. XBDM is distinct from KD and uses a different wire protocol.

Name Answering Protocol

An Xbox Development Kit (XDK) can be assigned a debug name that identifies it on the local network. XBDM provides the ability to resolve a debug name to an IP address (forward lookup), resolve an IP address to a debug name (reverse lookup), and discover all XDKs on the local network using a very simple UDP-based protocol.

A NAP packet contains 3 fields, the last of which is variable-length. The minimum length of a NAP packet is 2 bytes and the maximum is 257. Invalid packets are silently dropped by XBDM.

Type

This unsigned 8-bit field may contain the values 1 (lookup), 2 (reply), or 3 (wildcard).

Name Length

This unsigned 8-bit field specifies the length of the Name field and should be a value from 0 to 255. For Type 3 packets, this field should always be 0. For Type 1 and Type 2 packets, this field should never be 0.

Name

This variable-length field contains the ASCII-encoded debug name for Type 1 and Type 2 packets. The number of bytes in this field is given by the Length field. It should not contain any NUL characters.

Forward Lookup

To resolve a debug name to an IP address, send a Type 1 NAP packet containing the debug name to be resolved to UDP address 255.255.255.255:731. The XDK with that name will respond with a Type 2 NAP packet and its IP address can be retrieved from the UDP header. There is no way to prevent multiple XDKs being assigned the same debug name, so it's possible that the client may receive replies from multiple IP addresses.

Reverse Lookup

To resolve an IP address to a debug name, send a Type 3 NAP packet with no name (length 0) to the IP address on UDP port 731. Assuming the target is actually an XDK, it will respond with a Type 2 NAP packet containing its name. This is very similar to the Console Discovery process (below), except that by sending the wildcard packet to a single IP address, only that XDK will respond.

Console Discovery

To discover all XDKs on the local network, send a Type 3 NAP packet with no name (length 0) to the UDP address 255.255.255.255:731. Each XDK will respond with a Type 2 NAP packet containing its name. As with a forward lookup, the client may receive multiple replies with the same name, but different IP addresses.

Remote Debugging and Control Protocol

The Remote Debugging and Control Protocol (RDCP) is a text-based protocol transmitted over a TCP connection on port 731. RDCP resembles protocols like FTP and SMTP, making it possible to communicate with XBDM using just a Telnet client in many cases.

When a connection is established, XBDM sends 201- connected (or 200- connected in version 3944) followed by <CR><LF> (that is, a carriage return character followed by a line feed character). The RDCP client is then free to send a command followed by <CR><LF> or <CR><NUL>. A command consists of a name and zero or more parameters separated by whitespace characters. The format of the parameters is defined by the command, but most commands use the form key=value. Parameter values that contain whitespace characters must be surrounded by double quotes (e.g. "some value" or key="some value").

After executing a command, XBDM replies with a response line consisting of a three-digit status code and message of the form 999- message text<CR><LF>. Note that unlike similar protocols, the - (dash) is always present in responses and messages cannot span multiple lines.

Status codes

In responses, 2xx status codes indicate success and 4xx codes indicate failure. Most codes have a default message, but some commands leave the message field empty while others use the message field to hold whatever data was requested by the client or additional information about an error.

2xx Success

200- OK

Standard response for successful execution of a command.

201- connected

Initial response sent after a connection is established. The client does not need to send anything to solicit this response.

202- multiline response follows

The response line is followed by one or more additional lines of data terminated by a line containing only a . (period). The client must read all available lines before sending another command.

203- binary response follows

The response line is followed by raw binary data, the length of which is indicated in some command-specific way. The client must read all available data before sending another command.

204- send binary data

The command is expecting additional binary data from the client. After the client sends the required number of bytes, XBDM will send another response line with the final result of the command.

205- connection dedicated

The connection has been moved to a dedicated handler thread (see #Connection dedication).

4xx Failure

400- unexpected error

An internal error occurred that could not be translated to a standard error code. The message is typically more descriptive, such as "out of memory" or "bad parameter".

401- max number of connections exceeded

The connection could not be established because XBDM is already serving the maximum number of clients (4).

402- file not found

An operation was attempted on a file that does not exist.

403- no such module

An operation was attempted on a module that does not exist.

404- memory not mapped

An operation was attempted on a region of memory that is not mapped in the page table.

405- no such thread

An operation was attempted on a thread that does not exist.

406-

An attempt to set the system time with the setsystime command failed. This status code is undocumented.

407- unknown command

The command is not recognized.

408- not stopped

The target thread is not stopped.

409- file must be copied

A move operation was attempted on a file that can only be copied.

410- file already exists

A file could not be created or moved because one already exists with the same name.

411- directory not empty

A directory could not be deleted because it still contains files and/or directories.

412- filename is invalid

The specified file contains invalid characters or is too long.

413- file cannot be created

The file cannot be created for some unspecified reason.

414- access denied

The file cannot be accessed at the connection's current privilege level (see #Security).

415- no room on device

The target device has run out of storage space.

416- not debuggable

The title is not debuggable.

417- type invalid

The performance counter type is invalid.

418- data not available

The performance counter data is not available.

420- box not locked

The command can only be executed when security is enabled (see #Security).

421- key exchange required

The client must perform a key exchange with the keyxchg command (see #Security).

422- dedicated connection required

The command can only be executed on a dedicated connection (see #Connection dedication).

Connection dedication

Connection dedication is the process of moving a client connection from the global server thread to a threaded command handler thread with the dedicate command.

By default, commands sent to XBDM are processed on the global server thread. Built-in commands and custom command handlers registered with DmRegisterCommandProcessor are run on this thread and may only execute kernel APIs. Commands that need to call CRT or XAPI functions must run in a threaded command handler, registered with DmRegisterCommandProcessorEx or DmRegisterThreadedCommandProcessor.

A client that has not dedicated its connection will receive a 422- dedicated connection required response if it tries to execute a threaded command on the global server thread. After dedicating itself to a threaded command handler, the client can no longer send built-in or non-threaded commands until it re-dedicates itself to the global server thread.

Security

TODO

Commands

See also: XBDM commands by version

TODO

See Also

• Xbox Neighborhood – An XDK tool that utilizes the XBDM protocols

External Links

• Yelo Neighborhood – An open-source re-implementation of Xbox Neighborhood written in C#.
• ViridiX – An open-source collection of Xbox debugging libraries and tools written in C#.
• xbdm-rs - An open-source XBDM client written in Rust.