Update page 'Connection Protocol'

Connection Protocol.md

@@ -4,6 +4,60 @@ Connection Protocol
 ![Connection Sequence Diagram (Simplified)](https://gogs.blitter.com/RLabs/hkexsh/raw/master/hkexsh/hkexsh_seq.png)
 
 
+Sequence Diagram Source Code (rendering above diagram via [websequencediagrams.com](https://www.websequencediagrams.com/))
+```
+title HKExSh Connection Sequence
+participant "User (shell)" as L
+participant "User (shell)" as L
+participant Client as C
+participant "HKExNet Lib" as HL
+participant "Go pkg/net" as NL
+participant "Server Listener" as SL
+participant Server as S
+
+S-->+S: Listen()
+L-->+C: <<invoke client>>
+C->HL: Dial(prot, ipport, KExAlg, CAlg, HAlg)
+HL->NL: Dial(prot, ipport)
+NL->S:
+S-->+SL: Accept()
+SL->NL:
+NL->HL: c := net.Conn{}
+HL-->HL: hc := new hkexnet.Conn{c}
+note over HL: hc.cipheropts\n= (CAlg, HAlg)
+HL-->HL: hc.<KExAlg>DialSetup(c)
+
+HL->C: conn = hc
+
+#Client reads password from user
+C-->C: ReadPassword()
+C-->C: r := NewSession(op, uname,\nremHost, env, cmdStr, auth)
+par KEx
+#activate C
+C->SL: sendSessionParams(conn, r)
+activate SL
+SL->C:
+SL-->SL: auth(Client)
+SL->C: conn.Read(authReply)
+end
+C-->+C: doShellMode()
+par Encrypted
+C<->SL: r.Status := doShellMode(conn) / doCopyMode(conn)\n... (session) ...
+# ...
+# ...
+
+C-->SL: <<EOF/logout>>
+end
+SL-->C: <<Disconnect>>
+deactivate SL
+
+deactivate C
+C-->L: shell r.Status
+deactivate C
+C-->L: shell r.Status
+```
+
+
 ```
 Session: [ Op byte | Who []byte | ConnHost []byte | TermType []byte | Cmd []byte | AuthCookie []byte ]