From 9da83c9e1b69c4704886ab0c1011bf82a5009a59 Mon Sep 17 00:00:00 2001
From: hidnplayr <hidnplayr@kolibrios.org>
Date: Thu, 2 Nov 2017 18:22:06 +0000
Subject: [PATCH] Added some comments to TCP server demo app.

git-svn-id: svn://kolibrios.org@7108 a494cfbc-eb01-0410-851d-a64ba20cac60
---
 programs/network/tcpserv/tcpserv.asm | 37 +++++++++++++++++++++-------
 1 file changed, 28 insertions(+), 9 deletions(-)

diff --git a/programs/network/tcpserv/tcpserv.asm b/programs/network/tcpserv/tcpserv.asm
index 9aebfd28b..bb7df61e8 100644
--- a/programs/network/tcpserv/tcpserv.asm
+++ b/programs/network/tcpserv/tcpserv.asm
@@ -1,9 +1,9 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;                                                                 ;;
-;; Copyright (C) KolibriOS team 2010-2015. All rights reserved.    ;;
+;; Copyright (C) KolibriOS team 2010-2017. All rights reserved.    ;;
 ;; Distributed under terms of the GNU General Public License       ;;
 ;;                                                                 ;;
-;;  tcpserv.asm - TCP demo program for KolibriOS                   ;;
+;;  tcpserv.asm - TCP server demo program for KolibriOS            ;;
 ;;                                                                 ;;
 ;;  Written by hidnplayr@kolibrios.org                             ;;
 ;;                                                                 ;;
@@ -46,46 +46,59 @@ start:
         invoke  con_start, 1
         invoke  con_init, 80, 25, 80, 25, title
 
+; Set event mask to socket events only
         mcall   40, EVM_STACK
 
+; Write message str1 to the console
         invoke  con_write_asciiz, str1
 
+; Allocate a TCP socket
         mcall   socket, AF_INET4, SOCK_STREAM, 0
         cmp     eax, -1
         je      sock_err
+; Socket allocation succeeded, store it's number in socketnum
         mov     [socketnum], eax
 
-; This socket option is not implemented in kernel yet.
+; This might be needed in the future,
+; SO_REUSEADDR option is not implemented in kernel yet.
 ;        mcall   setsockopt, [socketnum], SOL_SOCKET, SO_REUSEADDR, &yes,
 ;        cmp     eax, -1
 ;        je      opt_err
 
+; Bind the socket to port 23 (as defined in sockaddr1)
         mcall   bind, [socketnum], sockaddr1, sockaddr1.length
         cmp     eax, -1
         je      bind_err
 
-        mcall   listen, [socketnum], 10 ; Backlog = 10
+; Start listening for incoming connections, with a backlog of max 1
+        mcall   listen, [socketnum], 1
         cmp     eax, -1
         je      listen_err
 
+; Write message str2 to the console
         invoke  con_write_asciiz, str2
 
+; (Wait for and) accept incoming connection
         mcall   accept, [socketnum], sockaddr1, sockaddr1.length
         cmp     eax, -1
         je      acpt_err
+; We have a new incoming connection, store the new socket number in socketnum2
         mov     [socketnum2], eax
 
+; Send a message on the incoming connection
         mcall   send, [socketnum2], hello, hello.length
 
+; Print the received data to the console, untill socket is closed by remote end
   .loop:
-        mcall   recv, [socketnum2], buffer, buffer.length, 0
+        mcall   recv, [socketnum2], buffer, BUFFERSIZE, 0
         cmp     eax, -1
         je      .loop
 
-        mov     byte[buffer+eax], 0
+        mov     byte[buffer+eax], 0             ; Zero-terminate the data, so we can print it
         invoke  con_write_asciiz, buffer
         jmp     .loop
 
+; Print error message
 acpt_err:
         invoke  con_write_asciiz, str8
         jmp     done
@@ -102,18 +115,25 @@ sock_err:
         invoke  con_write_asciiz, str6
         jmp     done
 
+
 done:
-        invoke  con_getch2      ; Wait for user input
+; Wait for user input
+        invoke  con_getch2
+; Close console
         invoke  con_exit, 1
 exit:
+; Close listening socket, if it is open
         cmp     [socketnum], 0
         je      @f
         mcall   close, [socketnum]
   @@:
+
+; Close second socket, if it is open
         cmp     [socketnum2], 0
         je      @f
         mcall   close, [socketnum2]
   @@:
+; Close application
         mcall   -1
 
 
@@ -133,7 +153,7 @@ hello   db      'Hello world!',0
 .length = $ - hello
 
 sockaddr1:
-        dw AF_INET4
+        dw AF_INET4             ; IPv4
 .port   dw 23 shl 8             ; port 23 - network byte order
 .ip     dd 0
         rb 10
@@ -160,7 +180,6 @@ i_end:
 socketnum       dd 0
 socketnum2      dd 0
 buffer          rb BUFFERSIZE
-.length = BUFFERSIZE
 
 align   4
 rb      4096    ; stack