Difference between revisions of "Pocket Minecraft Protocol"

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(Added packet 0x84)
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| class="col1 centeralign" | short
 
| class="col1 centeralign" | short
 
| class="col2 centeralign" | 1447
 
| class="col2 centeralign" | 1447
−
| class="col3" | Lenght of Null Payload in 0x05 or Lenght of 0x05 packet. Used to determine packet loss, maybe?
+
| class="col3" | Lenght of Null Payload in 0x05. Used to determine packet loss and max UDP packet size
 
|- class="row5"
 
|- class="row5"
 
| class="col0" | Total Size:
 
| class="col0" | Total Size:
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| class="col3" |  
 
| class="col3" |  
 
|- class="row6"
 
|- class="row6"
−
| class="col0 centeralign" | Unknown
+
| class="col0 centeralign" | Session ID?
 
| class="col1 centeralign" | int32
 
| class="col1 centeralign" | int32
 
| class="col2 centeralign" | -1476395009
 
| class="col2 centeralign" | -1476395009
Line 321: Line 321:
  
 
Server sends this packet in response to a 0x02 packet. It may be either a 0x1d or a 0x1c, depending on version.
 
Server sends this packet in response to a 0x02 packet. It may be either a 0x1d or a 0x1c, depending on version.
 +
 +
 +
{{anchor|0x84}}
 +
=== Unknown (0x84) ===
 +
 +
''Client to Server''
 +
 +
{| class="wikitable"
 +
|- class="row0"
 +
| class="col0" | Packet ID
 +
| class="col1" | Field Name
 +
| class="col2" | Field Type
 +
| class="col3" | Example
 +
| class="col4" | Notes
 +
|- class="row1"
 +
| class="col0 centeralign" rowspan="7" | 0x84
 +
| class="col1 centeralign" | Count
 +
| class="col2 centeralign" | byte
 +
| class="col3 centeralign" | 2
 +
| class="col4" | Count of 0x84 packets sent
 +
|- class="row2"
 +
| class="col0 centeralign" | Unknown
 +
| class="col1 centeralign" | 9 bytes
 +
| class="col2 centeralign" | Only seen 0x000040009000000009
 +
| class="col3" | Unknown, could be split in more fields
 +
|- class="row3"
 +
| class="col0 centeralign" | Unknown
 +
| class="col1 centeralign" | int
 +
| class="col2 centeralign" | Only seen 0xffffffff
 +
| class="col3" |
 +
|- class="row4"
 +
| class="col0 centeralign" | Session ID?
 +
| class="col1 centeralign" | int
 +
| class="col2 centeralign" | 0xb2e9b623
 +
| class="col3" | Same as last field of 0x07
 +
|- class="row5"
 +
| class="col0 centeralign" | Unknown
 +
| class="col1 centeralign" | 5 bytes
 +
| class="col2 centeralign" | Only seen 0x0000000000
 +
| class="col3" |
 +
|- class="row5"
 +
| class="col0 centeralign" | Unknown
 +
| class="col1 centeralign" | 4 bytes
 +
| class="col2 centeralign" | 0xa6b42b00
 +
| class="col3" | Last byte only seen as 0x00
 +
|- class="row6"
 +
| class="col0" | Total Size:
 +
| class="col1 rightalign" colspan="4" | 28 Bytes
 +
|}
 +
 +
Sent after 0x08. The client will send 5 0x84 packets, incrementing the count every time (starting at 0)
 +
  
 
[[Category:Pocket Minecraft]]
 
[[Category:Pocket Minecraft]]

Revision as of 12:21, 18 October 2012

Unlike the Minecraft protocol, this protocol uses UDP with (so far observed, at least) one message per packet. This makes the protocol easier to work with when it comes to packet serialization, and might offer latency improvements, but will inevitably have the usual UDP issues (packets lost, truncated, duplicated, out-of-order, etc.).

Old servers listen on UDP port 19132. As of the survival update, the port is the same Clients don't pick any specific port to listen on.

Please note that even where packet field names are written in this page, these are still largely hypothetical and could well be incorrect guesses.

It has been determined that PM uses RakNet for its networking library, some documentation that seems relevant.


Terminology

PM
Pocket Minecraft (aka Minecraft PE or Minecraft Pocket Edition)

Types

Size Range Notes
byte 1 -128 to 127 Signed, two's complement
short 2 -32768 to 32767 Signed, two's complement
int32 4 -2147483648 to 2147483647 Signed, two's complement
int64 8 Maybe a double?
MAGIC 16 0x00ffff00fefefefefdfdfdfd12345678 always hex bytes 0x00ffff00fefefefefdfdfdfd12345678, corresponding to RakNet's default OFFLINE_MESSAGE_DATA_ID
string ≥ 1 N/A Prefixed by a short containing the length of the string in characters. It appears that only the following ASCII characters can be displayed: !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~

Packets

All packets start with a single byte that identifies the packet type, the rest of the packet follows it.


ID_UNCONNECTED_PING_OPEN_CONNECTIONS (0x02)

Client to Broadcast

Packet ID Field Name Field Type Example Notes
0x02 Ping ID int64 0x0000000000301dfb Time since start in Milliseconds
MAGIC MAGIC
Total Size: 25 Bytes

Clients start out by sending this packet to the IP broadcast address on port 19132 repeatedly (approx once per second) when joining a server was chosen on the main screen, and stops when the user selects a server (or leaves the screen). The ping ID from the client increases over time, and appears to be the number of milliseconds since the client program was started (might be used to measure server response latency).


ID_OPEN_CONNECTION_REQUEST_1 (0x05)

Client to Server

Packet ID Field Name Field Type Example Notes
0x05 MAGIC MAGIC
Version byte 5 Client version, currently 5
Null Payload many 0x00 bytes 0x00 * 1447
Total Size: 18 Bytes + lenght of Null Payload

Sent from client after it receives packet 0x1d. The client will repeatedly send this with reducing sizes until it successfully receives a reply. Observed behaviour is that the client will send packets ~0.5s apart in the following way, until it gets a 0x06 response packet, or reaches the end of these: 4 packets of Null Payload lenght of 1447 4 packets of Null Payload lenght of 1155 5 packets of Null Payload lenght of 531 After this the client appears not to send any more packets to the server, but also doesn't (at least immediately) leave the "locating server" progress screen. If the server doesnt't reply the client, the client will display a "Connect Error" window


ID_OPEN_CONNECTION_REPLY_1 (0x06)

Server to Client

Packet ID Field Name Field Type Example Notes
0x05 MAGIC MAGIC
Server ID int64 This value seems to be constant for an installation of PM, or differs between the demo and full version.
Version byte 5 Server version, currently 5
Null Payload Lenght short 1447 Lenght of Null Payload in 0x05. Used to determine packet loss and max UDP packet size
Total Size: 28 Bytes

Sent from server after it receives packet 0x05.


ID_OPEN_CONNECTION_REQUEST_2 (0x07)

Client to Server

Packet ID Field Name Field Type Example Notes
0x07 MAGIC MAGIC
Unknown 5 bytes 0x043f57fefd
Unknown short 1087 Was Server port
Unknown short 22527
Unknown int32 1061862405
Session ID? int32 -1476395009
Total Size: 39 Bytes

Sent from client in response to packet 0x06.


ID_OPEN_CONNECTION_REPLY_2 (0x08)

Server to Client

Packet ID Field Name Field Type Example Notes
0x08 MAGIC MAGIC
Unknown int32 0xffffffff
Unknown int32
Unknown 5 bytes 0x043f57fefd
Unknown short Client UDP port?
Unknown int32
Unknown byte 0x00
Total Size: 37 Bytes

Sent from server in response to packet 0x07.


ID_ADVERTISE_SYSTEM (0x1d)

See 0x1c


ID_UNCONNECTED_PING_OPEN_CONNECTIONS (0x1c)

Server to Client

Packet ID Field Name Field Type Example Notes
0x1c Ping ID int64 0x0000000000301dfb Time since start in Milliseconds
Server ID int64
MAGIC MAGIC
Host Info string MCCPP;Demo;Steve Used to send the username
Total Size: 35 Bytes + lenght of string

Server sends this packet in response to a 0x02 packet. It may be either a 0x1d or a 0x1c, depending on version.


Unknown (0x84)

Client to Server

Packet ID Field Name Field Type Example Notes
0x84 Count byte 2 Count of 0x84 packets sent
Unknown 9 bytes Only seen 0x000040009000000009 Unknown, could be split in more fields
Unknown int Only seen 0xffffffff
Session ID? int 0xb2e9b623 Same as last field of 0x07
Unknown 5 bytes Only seen 0x0000000000
Unknown 4 bytes 0xa6b42b00 Last byte only seen as 0x00
Total Size: 28 Bytes

Sent after 0x08. The client will send 5 0x84 packets, incrementing the count every time (starting at 0)

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