Editing Common Text-based Response Protocol (section)

== Technical specification ==

=== Request format ===

Requests consist of a single line terminated by [[wp:CRLF|CRLF]] (<code>\r\n</code>):

{{Code example
| language = text
| caption  = Basic request format
| code     = COMMAND [arguments]\r\n
}}

The maximum request line length is 1024 bytes.

=== Response format ===

Responses begin with a status line, followed by optional content:

{{Code example
| language = text
| caption  = Response format
| code     = <status_code> <status_message>\r\n
[content lines]\r\n
.\r\n
}}

Content is terminated by a line containing only a period (<code>.</code>).

=== Status codes ===

CTRP uses a hierarchical status code system:

{| class="wikitable"
|-
! Range !! Category !! Description
|-
| 1x || Informational || Request received, continuing process
|-
| 2x || Success || Request successfully processed
|-
| 3x || Redirection || Further action needed
|-
| 4x || Client Error || Request contains bad syntax or cannot be fulfilled
|-
| 5x || Server Error || Server failed to fulfill valid request
|-
| 6x || Service Error || Service-level issues
|}

Common status codes:

{| class="wikitable"
|-
! Code !! Message !! Meaning
|-
| 20 || OK || Success
|-
| 21 || OK+MORE || Success, more content available
|-
| 40 || BAD REQUEST || Malformed request
|-
| 41 || NOT FOUND || Requested resource not found
|-
| 42 || FORBIDDEN || Access denied
|-
| 50 || ERROR || General server error
|-
| 51 || NOT IMPLEMENTED || Command not supported
|}

=== Encoding ===

All CTRP communication uses UTF-8 encoding with CRLF line endings. This ensures consistent handling across platforms while supporting international character sets.

=== Transport security ===

CTRP supports optional [[wp:Transport Layer Security|TLS]] encryption. Implementations typically offer both plain TCP and TLS-secured connections on separate ports.