MRCI/docs/Type_IDs.md

### 4.1 Type IDs ###

All mrci frames transferred throughout this application are usually passed into various functions using a ```uchar``` numeric value to indicate the type of data being passed with the ```QByteArray``` that are also usually passed into the functions. The type id enum values are as follows:

```
enum TypeID
{
    GEN_FILE    = 30,
    TEXT        = 31,
    ERR         = 32,
    PRIV_TEXT   = 33,
    IDLE        = 34,
    HOST_CERT   = 35,
    FILE_INFO   = 36,
    PEER_INFO   = 37,
    MY_INFO     = 38,
    PEER_STAT   = 39,
    P2P_REQUEST = 40,
    P2P_CLOSE   = 41,
    P2P_OPEN    = 42,
    BYTES       = 43,
    SESSION_ID  = 44,
    NEW_CMD     = 45,
    CMD_ID      = 46,
    BIG_TEXT    = 47
};
```

### 4.2 Type Descriptions ###
    
```TEXT```
This is text that can be displayed directly to the user or pass arguments for the command object to process.

format: ```[UTF-16LE_string] (no BOM)```

```GEN_FILE```
This is a file transfer type id that can be used to transfer any type of file type (music, photos, documents, etc...). It operates in its own protocol of sorts. The 1st GEN_FILE frame received by the host or client is TEXT parameters similar to what you see in terminal command lines with at least one of the arguments listed below. The next set of GEN_FILE frames received by the host or client is then the binary data that needs to be written to an open file or streamed until the limit defined in -len is meet.

The host or the client can be set as the sender or receiver of the GEN_FILE binary data. Which ever is designated as the receiver by the TEXT parameters need to send an empty GEN_FILE frame to start the process. An example if this can be found in section 4.3.

arguments:

* **-len (int)** | this is the integer value of the file size or amount of bytes to read/write.

* **-offset (int)** | this integer position tells where in the source or destination file to start reading/writing.

* **-client_file** (string) | this is the file path to the source/destination file in the client's file system.

* **-remote_file** (string) | this is the file path to the source/destination file in the host file system.

* **-single_step** | the presents of this argument tells both the client and host to operate in single step mode. single step mode causes the receiver of the binary data whether host or client to send an empty GEN_FILE frame after successfully receiving the data. this then tells the sender to send the next GEN_FILE frame containing binary data for the file and the cycle continues until len is meet. if this argument is not found, the sender can simply send all GEN_FILE data without waiting for an empty GEN_FILE from the receiver.

* **-to_host** | this argument should only come from host and it will define the client as the sender and the host as the receiver.

* **-from_host** | opposite affect to *-to_host*. it defines the host as the sender and the client as the receiver.

* **-truncate** | this indicates to whoever is the receiver to truncate the file being written to.

* **-force** | in some cases, the receiver might need to overwrite the target file. the presents of this argument tells it to overwrite without asking the user. the host should never send this argument and the client should ignore it if it is received from the host.

```ERR```
This type id is similar to TEXT except it indicates that this is an error message that can be displayed directly to the user if needed.

```PRIV_TEXT```
This id can be treated exactly like TEXT except this should tell the client to hide or do not echo the next TEXT data that the host is expecting, like a password or other sensitive text data.

```BIG_TEXT```
Also formatted exactly like TEXT but this indicates to the client that this is a large body of text that is recommended to be word wrapped when displaying to the user. It can contain line breaks so clients are also recommended to honor those line breaks.

```IDLE```
This doesn't carry any actual data, instead this indicates that the command id that sent it has finished it's task. Commands objects are not allowed to send this directly, the ```CmdExecutor``` will handle it.

```HOST_CERT```
Just as the name implies, this data type is used by the host to send the host SSL certificate while setting up an SSL connection.

```FILE_INFO```
This is a data structure that carries information about a file system object (file,dir,link).

```
  format:
  1. bytes[0]           - flags (8bit little endian uint)
  2. bytes[1-8]         - creation time in msec since Epoch UTC (64bit little endian uint)
  3. bytes[9-16]        - modification time in msec since Epoch UTC (64bit little endian uint)
  4. bytes[17-24]       - file size (64bit little endian uint)
  5. bytes[25-variable] - file name (UTF16-LE string, 16bit terminated)
  6. bytes[variable]    - symmlink target if it is a symmlink (UTF16-LE string, 16bit terminated)

  notes:
  1. 16bit terminated UTF-16LE strings are basically
     terminated by 2 bytes of 0x00.
  2. the symmlink target is empty if not a symmlink but
     the terminator should still be present.

  flags:
  1. bit 0 - true if the object is a file
  2. bit 1 - true if the object is a directory
  3. bit 2 - true if the object is a symmlink
  4. bit 3 - true if the current user have read permissions
  5. bit 4 - true if the current user have write permissions
  6. bit 5 - true if the current user have execute permissions
  7. bit 6 - true if the object exist in the file system. if symmlink,
             this determines if the symm target exists or not.
```

```PEER_INFO```
This carry some user account and session information about a peer client connected to the host.

```
  format:
  1. bytes[0-27]    28bytes  - session id (224bit hash)
  2. bytes[28-59]   32bytes  - user id (256bit hash)
  3. bytes[60-107]  48bytes  - user name (TEXT - padded with empty spaces)
  4. bytes[108-235] 128bytes - app name (TEXT - padded with empty spaces)
  5. bytes[236-299] 64bytes  - disp name (TEXT - padded with empty spaces)

  notes:
  1. the session id is unique to the peer's session connection only. it
     can change upon reconnection.
  2. the user id is unique to the peer's user account. is stays constant
     even when the user name changes and across all clients logged into
     the same account.
  3. the display name is the preffered display name of the peer. clients
     are encouraged to use this rather than the user name when displaying
     peer info to the user. if empty, it's ok to just fall back to the user
     name.
```

```MY_INFO```
This contains all of the information found in ```PEER_INFO``` for the local session but also includes the following:

```
  format:
  1. bytes[300-427] 128bytes - email (TEXT - padded with empty spaces)
  2. bytes[428-451] 24bytes  - group name (TEXT - padded with empty spaces)
  3. bytes[452]     1byte    - is email confirmed? (0x00 false, 0x01 true)
```

```NEW_CMD```
This contains information about a new command that was added to the current session.

```
  format:
  1. bytes[0-1]     2bytes   - 16bit LE unsigned int (command id)
  2. bytes[2]       1byte    - bool (0x01 or 0x00) (handles gen file)
  3. bytes[3-130]   128bytes - command name (TEXT - padded with empty spaces)
  4. bytes[131-258] 128bytes - library name (TEXT - padded with empty spaces)

  notes:
  1. the handles gen file flag is a single byte 0x01 to indicate true and
     0x00 to indicate false. clients need to be aware of which command
     handles the GEN_FILE mini protocol because it requires user input at
     both ends (host and client).
  2. the library name is what ever is returned by the command object's
     ExternCommand::libText() function. this can contain the module name
     and/or extra informaion the client can use to identify the command.
```

```CMD_ID```
This type id carries a 16bit unsigned LE int representing a command id.

format: ```2bytes - 16bit LE unsigned int (command id)```

```PEER_STAT```
This contain status information of a peer client when the peer changes sub-channels or disconnects from the host.

```
  format:
  1. bytes[0-27]  28bytes - session id (224bit hash)
  2. bytes[28-81] 54bytes - channel-sub ids
  3. bytes[82]    1byte   - is disconnected? (0x00 false, 0x01 true)

  notes:
  1. if (is disconnected) is set true (0x01) the session id will no longer
     be valid for that peer client so you should not make anymore attempts
     to send data to it.
  2. channel-sub ids is a string of 9byte channel-sub id combinations at
     a fixed length of 54bytes (padded with 0x00). this indicates what
     channels-subs the peer currently have open if the peer's channel ids
     no longer match with your session, it can be considered inactive or
     disconnected since you will no longer send/receive data with this peer.
```

```SESSION_ID```
This is a fixed length 28byte(224bit) sha3 hash of a client's session id connected to the host. This is unique to just the client's tcp connection with the host. This can change upon re-connection.

format: ```28bytes - session id (224bit sha3 hash)```

```P2P_REQUEST```
This is formatted extactly like ```PEER_INFO``` except this is allowed to be sent directly to the target peer without restriction when using the ```ExternCommand::toPeer()``` signal ([Command_Objects.md](Command_Objects.md), section 2.5). It will be up to the target peer to respond with a ```P2P_OPEN``` for the host to then unrestrict ```toPeer()``` so it will then be able to send/received other TypeIDs with this peer until ```P2P_CLOSE``` is sent/received. ```P2P_CLOSE``` can also be sent to decline the request. When sending this TypeID, the ```CmdExecutor``` will ignore the data passed into ```toPeer()``` from the command object and substitute with it's own generated ```P2P_REQUEST``` to prevent fraudulent request from getting sent out to all sessions; because of this, it is ok and preferable to send an empty ```P2P_REQUEST``` with the ```toPeer()``` signal.

```P2P_OPEN```
This contains a 28byte session id hash of the peer session that you or the peer will allow direct communication with when using the ```ExternCommand::toPeer()``` signal.

format: ```28bytes - session id (224bit sha3 hash)```

```P2P_CLOSE```
This contains a 28byte session id hash of the peer session that you or the peer want to close direct communication with when using the ```ExternCommand::toPeer()``` signal.

format: ```28bytes - session id (224bit sha3 hash)```

```BYTES```
This contains arbitrary binary data of any format that is not specialized for any internal objects in the host.

### 4.3 GEN_FILE Example ###

Setup:

* The host has a command called *upload_file* with a command id of *768* and handles the ```GEN_FILE``` data type.
* The client has a file called */home/foo/bar.mp3* and wants to upload it to the host file */home/host/music/bar.mp3* and the client knows the file size is 512bytes.

To upload the file, the client calls command id *768* with the following text arguments (must still be sent as a GEN_FILE):
```-client_file "/home/foo/bar.mp3" -remote_file "/home/host/music/bar.mp3" -len 512```

The host will then return the following the text arguments to the client (also sent as a GEN_FILE):
```-to_host```

This argument from the host designates it as the receiver so it will be up to the host to send an empty ```GEN_FILE``` to indicate to the client that it was ready to start receiving binary data from the client to write to */home/host/music/bar.mp3*. If that file already exists, the host will need to ask the user to overwrite or not.

If the host indicates that it's ready for the upload, the client can then simply read 512 bytes from */home/foo/bar.mp3* and send the read bytes to the host command id *768* as a ```GEN_FILE```.

The host will then write the bytes received from the client to */home/host/music/bar.mp3* and then auto terminate the command since 512 bytes has been meet.