tcp.inc

Menuet 操作系统源代码。 非常难得的东西

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;;                                                                 ;;
;;  TCP.INC                                                        ;;
;;                                                                 ;;
;;  TCP Processes for Menuet OS  TCP/IP stack                      ;;
;;                                                                 ;;
;;  Version 0.3  29 August 2002                                    ;;
;;                                                                 ;;
;;  Copyright 2002 Mike Hibbett, [e-mail]               ;;
;;                                                                 ;;
;;  See file COPYING for details                                   ;;
;;                                                                 ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   
   
;*******************************************************************
;   Interface
;
;       tcp_tx_handler      Handles the TCP transmit queue
;       tcp_rx              The protocol handler for received data
;       buildTCPPacket      fills in the packet headers and data
;       tcpStateMachine     Main state machine for received TCP packets
;
;*******************************************************************
   

;***************************************************************************
;   Function
;      tcp_tx_handler
;
;   Description
;       Handles queued TCP data
;       This is a kernel function, called by stack_handler
;
;***************************************************************************
tcp_tx_handler:
    ret


;***************************************************************************
;   Function
;      tcp_rx
;
;   Description
;       TCP protocol handler
;       This is a kernel function, called by ip_rx
;       IP buffer address given in edx
;          IP buffer number in eax
;          Free up (or re-use) IP buffer when finished
;
;***************************************************************************
tcp_rx:
    ; The process is as follows.
    ; Look for a socket with matching remote IP, remote port, local port
    ; if not found, then
    ; look for remote IP + local port match ( where sockets remote port = 0)
    ; if not found, then
    ; look for a socket where local socket port == IP packets remote port
    ; where sockets remote port, remote IP = 0
    ; discard if not found
    ; Call sockets tcbStateMachine, with pointer to packet.
    ; the state machine will not delete the packet, so do that here.

    push        eax
    
    ; Look for a socket where
    ; IP Packet TCP Destination Port = local Port
    ; IP Packet SA = Remote IP
    ; IP Packet TCP Source Port = remote Port
   
    mov     eax, SOCKETBUFFSIZE * NUM_SOCKETS
    mov     ecx, NUM_SOCKETS
ss1:
    sub     eax, SOCKETBUFFSIZE    
    movzx   ebx, word [edx + 22]     ; get the dest. port from the TCP hdr
    cmp     [eax + sockets + 12], bx ; compare with socket's local port
    jnz     nxttst1                        ; different - try next socket        

    movzx   ebx, word [edx + 20]       ; get the source port from the TCP hdr
    cmp     [eax + sockets + 20], bx ; compare with socket's remote port
    jnz     nxttst1                        ; different - try next socket        


    mov     ebx, [edx + 12]           ; get the source IP Addr from the IP hdr
    cmp     [eax + sockets + 16], ebx ; compare with socket's remote IP
    jnz     nxttst1                        ; different - try next socket        

    ; We have a complete match - use this socket
    jmp     tcprx_001

nxttst1:
    loop    ss1                     ; Return back if no match
   
    ; If we got here, there was no match
    ; Look for a socket where
    ; IP Packet TCP Destination Port = local Port
    ; IP Packet SA = Remote IP
    ; socket remote Port = 0
   
    mov     eax, SOCKETBUFFSIZE * NUM_SOCKETS
    mov     ecx, NUM_SOCKETS
    
ss2:
    sub     eax, SOCKETBUFFSIZE

    movzx   ebx, word [edx + 22]     ; get the dest. port from the TCP hdr
    cmp     [eax + sockets + 12], bx ; compare with socket's local port
    jnz     nxttst2                        ; different - try next socket        

    mov     ebx, [edx + 12]          ; get the source IP Addr from the IP hdr
    cmp     [eax + sockets + 16], ebx ; compare with socket's remote IP
    jnz     nxttst2                        ; different - try next socket        

    mov     ebx, 0
    cmp     [eax + sockets + 20], bx ; only match a remote socket of 0
    jnz     nxttst2                        ; different - try next socket        

    ; We have a complete match - use this socket
    jmp     tcprx_001

nxttst2:
    loop    ss2                     ; Return back if no match

    ; If we got here, there was no match
    ; Look for a socket where
    ; IP Packet TCP Destination Port = local Port
    ; socket Remote IP = 0
    ; socket remote Port = 0
   
    mov     eax, SOCKETBUFFSIZE * NUM_SOCKETS
    mov     ecx, NUM_SOCKETS
    
ss3:
    sub     eax, SOCKETBUFFSIZE

    movzx   ebx, word [edx + 22]     ; get destination port from the TCP hdr
    cmp     [eax + sockets + 12], bx ; compare with socket's local port
    jnz     nxttst3                        ; different - try next socket        

    mov     ebx, 0
    cmp     [eax + sockets + 20], bx ; only match a remote socket of 0
    jnz     nxttst3                        ; different - try next socket        

    mov     ebx, 0
    cmp     [eax + sockets + 16], ebx ; only match a socket remote IP of 0
    jnz     nxttst3                        ; different - try next socket        

    ; We have a complete match - use this socket
    jmp     tcprx_001

nxttst3:
    loop    ss3                     ; Return back if no match

    ; If we got here, we need to reject the packet
    inc     dword [dumped_rx_count]
    jmp     tcprx_exit
   
tcprx_001:   
    ; We have a valid socket/TCB, so call the TCB State Machine for that skt.
    ; socket is pointed to by [eax + sockets]
    ; IP packet is pointed to by [edx]
    ; IP buffer number is on stack ( it will be popped at the end)
    call    tcpStateMachine

tcprx_exit:    
    pop     eax
    call    freeBuff

    ret



;***************************************************************************
;   Function
;      buildTCPPacket
;
;   Description
;       builds an IP Packet with TCP data fully populated for transmission
;       You may destroy any and all registers
;          TCP control flags specified in bl
;          This TCB is in [sktAddr]
;          User data pointed to by esi
;       Data length in ecx
;          Transmit buffer number in eax
;
;***************************************************************************
buildTCPPacket:
    push    ecx                        ; Save data length
   
    ; convert buffer pointer eax to the absolute address
    mov     ecx, IPBUFFSIZE
    mul     ecx
    add     eax, IPbuffs

    mov     edx, eax

    mov     [edx + 33], bl            ; TCP flags
       
    mov     ebx, [sktAddr]
   
    ; So, ebx holds the socket ptr, edx holds the IPbuffer ptr
   
    ; Fill in the IP header ( some data is in the socket descriptor)
    mov     eax, [ebx + 8]
    mov     [edx + 12], eax      ; source IP
    mov     eax, [ebx + 16]
    mov     [edx + 16], eax      ; Destination IP
   
    mov     al, 0x45
    mov     [edx], al         ; Version, IHL
    xor     al, al   
    mov     [edx + 1], al     ; Type of service
   
    pop     eax                   ; Get the TCP data length
    push    eax
   
    add     eax, 20 + 20           ; add IP header and TCP header lengths
    mov     [edx + 2], ah
    mov     [edx + 3], al
    xor     al, al   
    mov     [edx + 4], al
    mov     [edx + 5], al
    mov     al, 0x40
    mov     [edx + 6], al
    xor     al, al  
    mov     [edx + 7], al
    mov     al, 0x20
    mov     [edx + 8], al
    mov     al, 6                         ; TCP protocol
    mov     [edx + 9], al
   
    ; Checksum left unfilled
    xor     ax, ax
    mov     [edx + 10], ax
   
    ; Fill in the TCP header ( some data is in the socket descriptor)
    mov     ax, [ebx + 12]
    mov     [edx + 20], ax        ; Local Port
   
    mov     ax, [ebx + 20]
    mov     [edx + 20 + 2], ax    ; desitination Port
   
    ; Checksum left unfilled
    xor     ax, ax
    mov     [edx + 20 + 16], ax
   
    ; sequence number
    mov     eax, [ebx + 48]
    mov     [edx + 20 + 4], eax
   
    ; ack number
    mov     eax, [ebx + 56]
    mov     [edx + 20 + 8], eax
   
    ; window ( 0x2000 )
    mov     ax, 0x0020
    mov     [edx + 20 + 14], ax
   
    ; Urgent pointer (0)
    mov     ax, 0
    mov     [edx + 20 + 18], ax
   
    ; data offset ( 0x50 )
    mov     al, 0x50
    mov     [edx + 20 + 12], al
   
    pop     ecx                  ; count of bytes to send
    mov     ebx, ecx            ; need the length later
   
    cmp     ebx, 0
    jz      btp_001
   
    mov     edi, edx
    add     edi, 40
    cld
    rep     movsb               ; copy the data across

btp_001:   
    ; we have edx as IPbuffer ptr.
    ; Fill in the TCP checksum
    ; First, fill in pseudoheader
    mov     eax, [edx + 12]
    mov     [pseudoHeader], eax
    mov     eax, [edx + 16]
    mov     [pseudoHeader+4], eax
    mov     ax, 0x0600            ; 0 + protocol
    mov     [pseudoHeader+8], ax
    add     ebx, 20
    mov     eax, ebx
    mov     [pseudoHeader+10], ah
    mov     [pseudoHeader+11], al
      
    mov     eax, pseudoHeader
    mov     [checkAdd1], eax
    mov     [checkSize1], word 12
    mov     eax, edx
    add     eax, 20
    mov     [checkAdd2], eax
    mov     eax, ebx
    mov     [checkSize2], ax     
   
    call    checksum
   
    ; store it in the TCP checksum ( in the correct order! )
    mov     ax, [checkResult]

    mov     [edx + 20 + 16], ah
    mov     [edx + 20 + 17], al
   
    ; Fill in the IP header checksum
    mov     eax, edx
    mov     [checkAdd1], eax
    mov     [checkSize1], word 20
    mov     [checkAdd2], dword 0
    mov     [checkSize2], word 0
   
    call    checksum
   
    mov     ax, [checkResult]
    mov     [edx + 10], ah
    mov     [edx + 11], al

    ret


; Increments the 32 bit value pointed to by esi in internet order
inc_inet_esi:
    push    eax
    add     esi, 3
    mov     al, byte[esi]
    inc     al
    mov     byte[esi], al
    cmp     al, 0
    jnz     iie_exit
    dec     esi
    mov     al, byte[esi]
    inc     al
    mov     byte[esi], al
    cmp     al, 0
    jnz     iie_exit
    dec     esi
    mov     al, byte[esi]
    inc     al
    mov     byte[esi], al
    jnz     iie_exit
    dec     esi
    mov     al, byte[esi]
    inc     al
    mov     byte[esi], al
    
iie_exit:
    pop     eax
    ret


; Increments the 32 bit value pointed to by esi in internet order
; by the value in ecx
add_inet_esi:
    push    eax

    mov     al, [esi]
    shl     eax, 8
    inc     esi
    mov     al, [esi]
    shl     eax, 8
    inc     esi
    mov     al, [esi]
    shl     eax, 8
    inc     esi
    mov     al, [esi]
    add     eax, ecx
    mov     [esi], al
    dec     esi
    shr     eax, 8
    mov     [esi], al
    dec     esi
    shr     eax, 8
    mov     [esi], al
    dec     esi
    shr     eax, 8
    mov     [esi], al
    pop     eax
    ret



TCBStateHandler:
    dd      stateTCB_LISTEN
    dd      stateTCB_SYN_SENT        
    dd      stateTCB_SYN_RECEIVED    
    dd      stateTCB_ESTABLISHED    
    dd      stateTCB_FIN_WAIT_1        
    dd      stateTCB_FIN_WAIT_2        
    dd      stateTCB_CLOSE_WAIT        
    dd      stateTCB_CLOSING            
    dd      stateTCB_LAST_ACK        
    dd      stateTCB_TIME_WAIT        
    dd      stateTCB_CLOSED            
    

;***************************************************************************
;   Function
;      tcpStateMachine
;
;   Description
;       TCP state machine
;       This is a kernel function, called by tcp_rx
;
;       IP buffer address given in [edx]
;          Socket/TCB address in [eax + sockets]
;
;       The IP buffer will be released by the caller
;***************************************************************************
tcpStateMachine:
    mov     ebx, sockets
    add     ebx, eax
    mov     [sktAddr], ebx

    ; Call handler for given TCB state
    mov     ebx, [eax + sockets+28]
    cmp     ebx, TCB_LISTEN
    jb      tsm_exit
    cmp     ebx, TCB_CLOSED
    ja      tsm_exit
    
    dec     ebx
    call    dword [TCBStateHandler+ebx*4]
    
tsm_exit:
    ret



stateTCB_LISTEN: