From e9aebac1a2a4732763c2f7e4428a23983d4eb6a3 Mon Sep 17 00:00:00 2001
From: bt <bt@rctt.net>
Date: Fri, 10 Apr 2026 19:31:31 +0200
Subject: [common] Exchange messages between servers

---
 docs/rfc.md | 69 ++++++++++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 55 insertions(+), 14 deletions(-)

(limited to 'docs/rfc.md')

diff --git a/docs/rfc.md b/docs/rfc.md
index 8c5818e..8296cfa 100644
--- a/docs/rfc.md
+++ b/docs/rfc.md
@@ -153,15 +153,16 @@ Payload type attributes describes following characteristics:
 * C - Client: can be send only by a client
 * E - Empty: signals an event but does not carry any data
 
-| Type | Name      | Attributes |
-|------|-----------|------------|
-| 0x00 |           | R          |
-| 0x01 | Success   |  SCE       |
-| 0x02 | Error     |  S         |
-| 0x03 | Handshake |  SC        |
-| 0x04 | Auth      |   C        |
-| 0x05 | Message   |  SC        |
-| 0xFF | Test      | R          |
+| Type | Name       | Attributes |
+|------|------------|------------|
+| 0x00 |            | R          |
+| 0x01 | Success    |  SCE       |
+| 0x02 | Error      |  S         |
+| 0x03 | Handshake  |  SC        |
+| 0x04 | UserAuth |   C        |
+| 0x05 | Message    |  SC        |
+| 0x06 | ServerAuth | S          |
+| 0xFF | Test       | R          |
 
 ### Success
 
@@ -177,8 +178,9 @@ Payload is always empty for this type.
 
 | Type | Description                                               |
 |------|-----------------------------------------------------------|
-| 0x01 | Auth failed. Invalid username or password.                |
+| 0x01 | Client auth failed. Invalid username or password.         |
 | 0x02 | Not found. User or channel cannot access user or channel. |
+| 0x03 | Server auth failed. Unknown name.                        |
 
 ### Handshake
 
@@ -200,13 +202,19 @@ different auth method will be used.
 | 0x01 | User -> Server   |
 | 0x02 | Server -> Server |
 
-### Auth
+### UserAuth
 
 | Type   | Name     |
 |--------|----------|
 | string | username |
 | string | password |
 
+### ServerAuth
+
+| Type   | Name     |
+|--------|----------|
+| string | name     |
+
 ### Message
 
 | Type      | Name            |
@@ -238,7 +246,7 @@ Some operations require multiple rounds of communication.
 In this case payloads are send in a sequence. Payload that is not part of this
 specific operation (for example incoming message) cannot interrupt this process.
 
-### Connection initialisation
+### Client-Server connection initialisation
 
 ~~~ ascii-art
 +--------+                   +--------+
@@ -254,7 +262,7 @@ specific operation (for example incoming message) cannot interrupt this process.
      |                            +- If [ver_major] does not match server
      |                            |  protocol version close the connection
      |                            |
-     | Send [Auth]                |
+     | Send [UserAuth]          |
      +--------------------------->|
      |                            |
      | Send [Error 0x01]          |
@@ -263,4 +271,37 @@ specific operation (for example incoming message) cannot interrupt this process.
      |                            |
      | Send [Sucesss]             |
      |<---------------------------+
-~~~
\ No newline at end of file
+~~~
+
+### Server-Server connection initialisation
+
+~~~ ascii-art
++--------+                   +--------+
+| Server |                   | Server |
++----+---+                   +----+---+
+     |                            |
+     | Initialise TCP connection  |
+     +--------------------------->|
+     |                            |
+     | Send [Handshake]           |
+     +--------------------------->|
+     |                            |
+     |                            +- If [ver_major] does not match server
+     |                            |  protocol version close the connection
+     |                            |
+     | Send [ServerAuth]          |
+     +--------------------------->|
+     |                            |
+     | Send [Error 0x03]          |
+     |<---------------------------+- If [name] is not present in known public
+     |                            |  keys list.
+     |                            |
+     | Send [Sucesss]             |
+     |<---------------------------+
+~~~
+
+## Server to server operation
+
+Exchanging messages between SOLEC servers is a core concept behind the project.
+Sending message to user residing on a different server require estabilishing a
+connection between both servers.
-- 
cgit v1.2.3