kolibrios/kernel/branches/net/network/tcp_subr.inc

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;                                                                 ;;
;; Copyright (C) KolibriOS team 2004-2012. All rights reserved.    ;;
;; Distributed under terms of the GNU General Public License       ;;
;;                                                                 ;;
;;  Part of the TCP/IP network stack for KolibriOS                 ;;
;;                                                                 ;;
;;   Written by hidnplayr@kolibrios.org                            ;;
;;                                                                 ;;
;;    Based on the code of 4.4BSD                                  ;;
;;                                                                 ;;
;;          GNU GENERAL PUBLIC LICENSE                             ;;
;;             Version 2, June 1991                                ;;
;;                                                                 ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

$Revision$

align 4
iglobal
        TCP_backoff     db 0,1,2,3,4,5,6,6,6,6,6,6,6
endg

macro   TCP_checksum IP1, IP2 {

;-------------
; Pseudoheader

        ; protocol type
        mov     edx, IP_PROTO_TCP

        ; source address
        add     dl, byte [IP1+1]
        adc     dh, byte [IP1+0]
        adc     dl, byte [IP1+3]
        adc     dh, byte [IP1+2]

        ; destination address
        adc     dl, byte [IP2+1]
        adc     dh, byte [IP2+0]
        adc     dl, byte [IP2+3]
        adc     dh, byte [IP2+2]

        ; size
        adc     dl, cl
        adc     dh, ch

        adc     edx, 0

;---------------------
; Real header and data

        push    esi
        call    checksum_1
        call    checksum_2
        pop     esi

}       ; returns in dx only




macro   TCP_sendseqinit ptr {

        push    edi                     ;;;; i dont like this static use of edi
        mov     edi, [ptr + TCP_SOCKET.ISS]
        mov     [ptr + TCP_SOCKET.SND_UP], edi
        mov     [ptr + TCP_SOCKET.SND_MAX], edi
        mov     [ptr + TCP_SOCKET.SND_NXT], edi
        mov     [ptr + TCP_SOCKET.SND_UNA], edi
        pop     edi

}



macro   TCP_rcvseqinit ptr {

        push    edi
        mov     edi, [ptr + TCP_SOCKET.IRS]
        inc     edi
        mov     [ptr + TCP_SOCKET.RCV_NXT], edi
        mov     [ptr + TCP_SOCKET.RCV_ADV], edi
        pop     edi

}



macro   TCP_init_socket socket {

        mov     [socket + TCP_SOCKET.t_maxseg], TCP_mss_default
        mov     [socket + TCP_SOCKET.t_flags], TF_REQ_SCALE or TF_REQ_TSTMP

        mov     [socket + TCP_SOCKET.t_srtt], TCP_time_srtt_default
        mov     [socket + TCP_SOCKET.t_rttvar], TCP_time_rtt_default * 4
        mov     [socket + TCP_SOCKET.t_rttmin], TCP_time_re_min
;;; TODO: TCP_time_rangeset

        mov     [socket + TCP_SOCKET.SND_CWND], TCP_max_win shl TCP_max_winshift
        mov     [socket + TCP_SOCKET.SND_SSTHRESH], TCP_max_win shl TCP_max_winshift


}


;---------------------------
;
; TCP_pull_out_of_band
;
; IN:  eax =
;      ebx = socket ptr
;      edx = tcp packet ptr
;
; OUT: /
;
;---------------------------

align 4
TCP_pull_out_of_band:

        DEBUGF  1,"TCP_pull_out_of_band\n"

        ;;;; 1282-1305

        ret








;-------------------------
;
; TCP_drop
;
;  IN:  eax = socket ptr
;       ebx = error number
;
;  OUT: eax = socket ptr
;
;-------------------------
align 4
TCP_drop:

        DEBUGF  1,"TCP_drop: %x\n", eax

        cmp     [eax + TCP_SOCKET.t_state], TCPS_SYN_RECEIVED
        jb      .no_syn_received

        mov     [eax + TCP_SOCKET.t_state], TCPS_CLOSED

        call    TCP_output

;;; TODO: update stats

        jmp     TCP_close

  .no_syn_received:

;;; TODO: update stats

;;; TODO: check if error code is "Connection timed out' and handle accordingly

        mov     [eax + SOCKET.errorcode], ebx








;-------------------------
;
; TCP_close
;
;  IN:  eax = socket ptr
;  OUT: eax = socket ptr
;
;-------------------------
align 4
TCP_close:

        DEBUGF  1,"TCP_close: %x\n", eax

;;; TODO: update RTT and mean deviation
;;; TODO: update slow start threshold

        call    SOCKET_is_disconnected
        call    SOCKET_free

        ret




;-------------------------
;
; TCP_outflags
;
;  IN:  eax = socket ptr
;
;  OUT: edx = flags
;
;-------------------------
align 4
TCP_outflags:

        mov     edx, [eax + TCP_SOCKET.t_state]
        movzx   edx, byte [edx + .flaglist]

        DEBUGF  1,"TCP_outflags: socket=%x flags=%x\n", eax, dl

        ret

  .flaglist:

        db      TH_RST + TH_ACK         ; TCPS_CLOSED
        db      0                       ; TCPS_LISTEN
        db      TH_SYN                  ; TCPS_SYN_SENT
        db      TH_SYN + TH_ACK         ; TCPS_SYN_RECEIVED
        db               TH_ACK         ; TCPS_ESTABLISHED
        db               TH_ACK         ; TCPS_CLOSE_WAIT
        db      TH_FIN + TH_ACK         ; TCPS_FIN_WAIT_1
        db      TH_FIN + TH_ACK         ; TCPS_CLOSING
        db      TH_FIN + TH_ACK         ; TCPS_LAST_ACK
        db               TH_ACK         ; TCPS_FIN_WAIT_2
        db               TH_ACK         ; TCPS_TIMED_WAIT






;---------------------------------------
;
; The fast way to send an ACK/RST/keepalive segment
;
; TCP_respond
;
;  IN:  ebx = socket ptr
;        cl = flags
;
;--------------------------------------
align 4
TCP_respond:

        DEBUGF  1,"TCP_respond_socket: socket=%x flags=%x\n", ebx, cl

;---------------------
; Create the IP packet

        push    cx ebx
        mov     eax, [ebx + IP_SOCKET.RemoteIP]
        mov     edx, [ebx + IP_SOCKET.LocalIP]
        mov     ecx, sizeof.TCP_header
        mov     di, IP_PROTO_TCP shl 8 + 128
        call    IPv4_output
        test    edi, edi
        jz      .error
        pop     esi cx
        push    edx eax

;-----------------------------------------------
; Fill in the TCP header by using the socket ptr

        mov     ax, [esi + TCP_SOCKET.LocalPort]
        stosw
        mov     ax, [esi + TCP_SOCKET.RemotePort]
        stosw
        mov     eax, [esi + TCP_SOCKET.SND_NXT]
        bswap   eax
        stosd
        mov     eax, [esi + TCP_SOCKET.RCV_NXT]
        bswap   eax
        stosd
        mov     al, 0x50        ; Dataoffset: 20 bytes (TCP_header.DataOffset)
        stosb
        mov     al, cl
        stosb
;        mov     ax, [esi + TCP_SOCKET.RCV_WND]
;        rol     ax, 8
        mov     ax, 0x00a0      ;;;;;;; FIXME
        stosw                   ; window
        xor     eax, eax
        stosd                   ; checksum + urgentpointer

;---------------------
; Fill in the checksum

  .checksum:
        sub     edi, sizeof.TCP_header
        mov     ecx, sizeof.TCP_header
        xchg    esi, edi
        TCP_checksum (edi + IP_SOCKET.LocalIP), (edi + IP_SOCKET.RemoteIP)
        mov     [esi+TCP_header.Checksum], dx

;--------------------
; And send the segment

        call    [ebx + NET_DEVICE.transmit]
        ret

  .error:
        DEBUGF  1,"TCP_respond_socket: failed\n"
        add     esp, 2 + 4

        ret








;-------------------------
; TCP_respond_segment:
;
;  IN:  edx = segment ptr (a previously received segment)
;       edi = ptr to dest and src IPv4 addresses
;        cl = flags

align 4
TCP_respond_segment:

        DEBUGF  1,"TCP_respond_segment: frame=%x flags=%x\n", edx, cl

;---------------------
; Create the IP packet

        push    cx edx
        mov     ebx, [edi + 4]
        mov     eax, [edi]
        mov     ecx, sizeof.TCP_header
        mov     di, IP_PROTO_TCP shl 8 + 128
        call    IPv4_output
        jz      .error
        pop     esi cx

        push    edx eax

;---------------------------------------------------
; Fill in the TCP header by using a received segment

        mov     ax, [esi + TCP_header.DestinationPort]
        stosw
        mov     ax, [esi + TCP_header.SourcePort]
        stosw
        mov     eax, [esi + TCP_header.AckNumber]
        bswap   eax
        stosd
        xor     eax, eax
        stosd
        mov     al, 0x50        ; Dataoffset: 20 bytes (sizeof.TCP_header)
        stosb
        mov     al, cl
        stosb
        mov     ax, 1280
        rol     ax, 8
        stosw                   ; window
        xor     eax, eax
        stosd                   ; checksum + urgentpointer

;---------------------
; Fill in the checksum

        lea     esi, [edi - sizeof.TCP_header]
        mov     ecx, sizeof.TCP_header
        TCP_checksum (esi - sizeof.IPv4_header + IPv4_header.DestinationAddress),\      ; FIXME
                     (esi - sizeof.IPv4_header + IPv4_header.SourceAddress)
        mov     [esi + TCP_header.Checksum], dx

;--------------------
; And send the segment

        call    [ebx + NET_DEVICE.transmit]
        ret

  .error:
        DEBUGF  1,"TCP_respond_segment: failed\n"
        add     esp, 2+4

        ret


macro   TCPT_RANGESET   timer, value, min, max {

local   .min
local   .max
local   .done

        cmp     value, min
        jb      .min
        cmp     value, max
        ja      .max

        mov     timer, value
        jmp     .done

  .min:
        mov     timer, value
        jmp     .done

  .max:
        mov     timer, value
        jmp     .done

  .done:
}


align 4
TCP_set_persist:

; First, check if retransmit timer is not set, retransmit and persist are mutually exclusive

        cmp     [eax + TCP_SOCKET.timer_retransmission], 0
        jg      @f

; calculate RTO

        push    ebx
        mov     ebx, [eax + TCP_SOCKET.t_srtt]
        shr     ebx, 2
        add     ebx, [eax + TCP_SOCKET.t_rttvar]
        shr     ebx, 1

        mov     cl, [eax + TCP_SOCKET.t_rxtshift]
        shl     ebx, cl

; Start/restart persistance timer.

        TCPT_RANGESET   [eax + TCP_SOCKET.timer_persist], ebx, TCP_time_pers_min, TCP_time_pers_max

        pop     ebx

        cmp     [eax + TCP_SOCKET.t_rxtshift], TCP_max_rxtshift
        jae     @f
        inc     [eax + TCP_SOCKET.t_rxtshift]
      @@:

        ret



; eax = rtt
; ebx = socket ptr

align 4
TCP_xmit_timer:

        DEBUGF  1,"TCP_xmit_timer: socket=%x rtt=%d0ms\n", ebx, eax

;TODO: update stats

        cmp     [ebx + TCP_SOCKET.t_rtt], 0
        je      .no_rtt_yet

; srtt is stored as a fixed point with 3 bits after the binary point.
; The following magic is equivalent of the smoothing algorithm in rfc793 with an alpha of .875
; (srtt = rtt/8 + srtt*7/8 in fixed point)
; Adjust rtt to origin 0.

        push    ecx
        mov     ecx, [ebx + TCP_SOCKET.t_srtt]
        shr     ecx, TCP_RTT_SHIFT
        sub     eax, ecx
        dec     eax
        pop     ecx

        add     [ebx + TCP_SOCKET.t_srtt], eax
        ja      @f
        mov     [ebx + TCP_SOCKET.t_srtt], 1
  @@:

; We accumulate a smoothed rtt variance (actually, a smoothed mean difference),
; then set the retransmit timer to smoothed rtt + 4 times the smoothed variance.
; rttvar is stored as fixed point with 2 bits after the binary point.
; The following is equivalent to rfc793 smoothing with an alpha of .75
; (rttvar = rttvar*3/4 + delta/4) (delta = eax)

; get abs(eax)
        push    edx
        cdq
        xor     eax, edx
        sub     eax, edx

        mov     edx, [ebx + TCP_SOCKET.t_rttvar]
        shr     edx, TCP_RTTVAR_SHIFT
        sub     eax, edx
        pop     edx

        add     [ebx + TCP_SOCKET.t_rttvar], eax
        ja      @f
        mov     [ebx + TCP_SOCKET.t_rttvar], 1
  @@:
        ret


  .no_rtt_yet:

        push    ecx
        mov     ecx, eax
        shl     ecx, TCP_RTT_SHIFT
        mov     [ebx + TCP_SOCKET.t_srtt], ecx

        shl     eax, TCP_RTTVAR_SHIFT - 1
        mov     [ebx + TCP_SOCKET.t_rttvar], eax
        pop     ecx

        ret




; eax = max segment size
; ebx = socket ptr
align 4
TCP_mss:

        cmp     eax, 1420                               ; FIXME
        jbe     @f
        mov     eax, 1420
  @@:
        mov     [ebx + TCP_SOCKET.t_maxseg], eax


        ret