WebSVN – Kolibri OS – Diff – /kernel/trunk/network/tcp_input.inc

+align 4
+proc TCP_process_input
 locals
-align 4
+        dataoffset      dd ?
-TCP_process_input:
+endl
         pop     edx ecx
         jne     .drop_no_socket
   .checksum_ok:
+; Verify the data offset
-; Verify the data offset
+        movzx   eax, [edx + TCP_header.DataOffset]
-        and     [edx + TCP_header.DataOffset], 0xf0                     ; Calculate TCP segment header size (throwing away unused reserved bits in TCP header)
+        and     al, 0xf0                        ; Calculate TCP segment header size (throwing away unused reserved bits in TCP header)
-        shr     [edx + TCP_header.DataOffset], 2
+        shr     al, 2
-        cmp     [edx + TCP_header.DataOffset], sizeof.TCP_header        ; Now see if it's at least the size of a standard TCP header
+        cmp     al, sizeof.TCP_header           ; Now see if it's at least the size of a standard TCP header
+        jb      .drop_no_socket                 ; If not, drop the packet
-        jb      .drop_no_socket                                         ; If not, drop the packet
         mov     [dataoffset], eax
         movzx   eax, [edx + TCP_header.DataOffset]
         sub     ecx, eax                                                ; substract TCP header size from total segment size
         jb      .drop_no_socket                                         ; If total segment size is less then the advertised header size, drop packet
         or      [ebx + TCP_SOCKET.timer_flags], timer_flag_keepalive
 ;--------------------
+; Process TCP options
+;;; FIXME: for LISTEN, options should be called after we determined route, we need it for MSS
+;;;        cmp     [ebx + TCP_SOCKET.t_state], TCPS_LISTEN ; no options when in listen state
-; Process TCP options
+;;;        jz      .not_uni_xfer                           ; also no header prediction
         push    ecx
-        movzx   ecx, [edx + TCP_header.DataOffset]
+        mov     ecx, [dataoffset]
-        cmp     ecx, sizeof.TCP_header                  ; Does header contain any options?
-        je      .no_options
-        DEBUGF  DEBUG_NETWORK_VERBOSE, "TCP_input: Segment has options\n"
         cmp     ecx, sizeof.TCP_header                  ; Does header contain any options?
-;;; FIXME: for LISTEN, options should be called after we determined route, we need it for MSS
+        je      .no_options
 ;;;        cmp     [ebx + TCP_SOCKET.t_state], TCPS_LISTEN ; no options when in listen state
-;;;        jz      .not_uni_xfer                           ; also no header prediction
+        DEBUGF  DEBUG_NETWORK_VERBOSE, "TCP_input: Segment has options\n"
         jne     .no_options                     ; error occured, ignore all options!
         test    [edx + TCP_header.Flags], TH_SYN
+        jz      @f
         jz      @f
         xor     eax, eax
         lodsw
         rol     ax, 8
-        DEBUGF  DEBUG_NETWORK_VERBOSE, "TCP_input: Maxseg=%u\n", ax
+        DEBUGF  DEBUG_NETWORK_VERBOSE, "TCP_input: Maxseg=%u\n", eax
         call    TCP_mss
         DEBUGF  DEBUG_NETWORK_VERBOSE, "TCP_input: Header prediction: we are receiving %u bytes\n", ecx
         add     [ebx + TCP_SOCKET.RCV_NXT], ecx         ; Update sequence number with number of bytes we have copied
-        movzx   esi, [edx + TCP_header.DataOffset]
+        mov     esi, [dataoffset]
         add     esi, edx
         je      .SYN_SENT
 ;----------------------------
 ; trim any data not in window
 ; 1. Check for duplicate data at beginning of segment
 ; check for duplicate data at beginning of segment (635)
 ; Calculate number of bytes we need to drop
         mov     eax, [ebx + TCP_SOCKET.RCV_NXT]
         and     [edx + TCP_header.Flags], not (TH_URG)
   .dup_syn:
         dec     eax
   .no_dup_syn:
-; Check for entire duplicate segment (646)
+; 2. Check for entire duplicate segment
         cmp     eax, ecx                ; eax holds number of bytes to drop, ecx is data size
         jb      .duplicate
         jnz     @f
         test    [edx + TCP_header.Flags], TH_FIN
 ; At this point the FIN must be out of sequence or a duplicate, drop it
         and     [edx + TCP_header.Flags], not TH_FIN
 ; send an ACK and resynchronize and drop any data.
-; But keep on processing for RST or ACK
-        DEBUGF  DEBUG_NETWORK_VERBOSE,  "616\n"
+; But keep on processing for RST or ACK
         or      [ebx + TCP_SOCKET.t_flags], TF_ACKNOW
+        mov     eax, ecx
-        mov     eax, ecx
-;TODO: update stats
+;;; TODO: update stats
 ;-----------------------------------------------
+; Remove duplicate data and update urgent offset
+  .duplicate:
-; Remove duplicate data and update urgent offset
+        DEBUGF  1,  "TCP_input: trimming duplicate data\n"
-  .duplicate:
+; Trim data from left side of window
-;;; TODO: 677
+        add     [dataoffset], eax
         add     [edx + TCP_header.SequenceNumber], eax
         sub     ecx, eax
         sub     [edx + TCP_header.UrgentPointer], ax
         jg      @f
         and     [edx + TCP_header.Flags], not (TH_URG)
         mov     [edx + TCP_header.UrgentPointer], 0
        @@:
 ;--------------------------------------------------
-; Handle data that arrives after process terminates (687)
+; Handle data that arrives after process terminates
   .no_duplicate:
         call    TCP_close
-;;;TODO: update stats
+;;; TODO: update stats
         jmp     .respond_seg_reset
 ;----------------------------------------
-; Remove data beyond right edge of window (700-736)
+; Remove data beyond right edge of window
   .not_terminated:
         mov     eax, [edx + TCP_header.SequenceNumber]
         mov     eax, ebx
         call    TCP_close
         jmp     .findpcb        ; FIXME: skip code for unscaling window, ...
   .no_new_request:
-; If window is closed can only take segments at window edge, and have to drop data and PUSH from
+; If window is closed, we can only take segments at window edge, and have to drop data and PUSH from
 ; incoming segments. Continue processing, but remember to ACK. Otherwise drop segment and ACK
         cmp     [ebx + TCP_SOCKET.RCV_WND], 0
         jne     .drop_after_ack
-        mov     eax, [edx + TCP_header.SequenceNumber]
+        mov     esi, [edx + TCP_header.SequenceNumber]
-        cmp     eax, [ebx + TCP_SOCKET.RCV_NXT]
-        jne     .drop_after_ack
+        cmp     esi, [ebx + TCP_SOCKET.RCV_NXT]
         jne     .drop_after_ack
-        DEBUGF  DEBUG_NETWORK_VERBOSE,  "690\n"
         or      [ebx + TCP_SOCKET.t_flags], TF_ACKNOW
-;;; TODO: update stats
+        or      [ebx + TCP_SOCKET.t_flags], TF_ACKNOW
-        jmp     .no_excess_data
-  .dont_drop_all:
 ;;; TODO: update stats
+  .dont_drop_all:
-;;; TODO: 733
+;;; TODO: update stats
         DEBUGF  1, "Trimming %u bytes from the right of the window\n"
-        sub     ecx, eax
+        sub     ecx, eax        ; remove data from the right side of window (decrease data length)
         and     [ebx + TCP_SOCKET.t_flags], not (TH_PUSH or TH_FIN)
   .no_excess_data:
 ;-----------------
-; Record timestamp (737-746)
+; Record timestamp
   .trim_then_step6:
+        inc     [edx + TCP_header.SequenceNumber]
+; Drop any received data that doesnt fit in the receive window.
+        cmp     ecx, [ebx + TCP_SOCKET.RCV_WND]
+        jbe     .dont_trim
+        DEBUGF  DEBUG_NETWORK_VERBOSE, "TCP_input: received data does not fit in window, trimming %u bytes\n", eax
+        mov     ecx, [ebx + TCP_SOCKET.RCV_WND]
+        and     [edx + TCP_header.Flags], not (TH_FIN)
-        inc     [edx + TCP_header.SequenceNumber]
+;;; TODO: update stats
-;;; TODO: Drop any received data that follows receive window (590)
+  .dont_trim:
 ; Ok, lets do this..  Set delayed ACK flag and copy data into socket buffer
         or      [ebx + TCP_SOCKET.t_flags], TF_DELACK
         pusha
-        movzx   esi, [edx + TCP_header.DataOffset]
+        mov     esi, [dataoffset]
         add     esi, edx
         lea     eax, [ebx + STREAM_SOCKET.rcv]
         call    SOCKET_ring_write                       ; Add the data to the socket buffer
         call    SOCKET_notify
         jmp     .data_done
-  .out_of_order:
+  .out_of_order:
         DEBUGF  DEBUG_NETWORK_VERBOSE,  "TCP data is out of order!\nSequencenumber is %u, we expected %u.\n", \
-        DEBUGF  DEBUG_NETWORK_VERBOSE,  "TCP data is out of order\n"
+        [edx + TCP_header.SequenceNumber], [ebx + TCP_SOCKET.RCV_NXT]
+; Uh-oh, some data is out of order, lets call TCP reassemble for help
 ; Uh-oh, some data is out of order, lets call TCP reassemble for help
         call    TCP_reassemble
         call    TCP_reassemble
         DEBUGF  DEBUG_NETWORK_VERBOSE, "TCP_input: Drop (no socket)\n"
         call    NET_packet_free
         add     esp, 4
+        jmp     .loop

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(root)/kernel/trunk/network/tcp_input.inc – Rev 4296 → 4339