1037 lines
27 KiB
ArmAsm
1037 lines
27 KiB
ArmAsm
; TCP (transmission control protocol) functions
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; NB to use these functions, you must pass "-DTCP" to ca65 when assembling "ip.s"
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; otherwise inbound tcp packets won't get passed in to tcp_process
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; currently only a single outbound (client) connection is supported
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; to use, first call "tcp_connect" to create a connection. to send data on that connection, call "tcp_send".
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; whenever data arrives, a call will be made to the routine pointed at by tcp_callback.
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MAX_TCP_PACKETS_SENT = 8 ; timeout after sending 8 messages will be about 7 seconds (1+2+3+4+5+6+7+8)/4
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.include "zeropage.inc"
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.include "../inc/common.inc"
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.include "../inc/error.inc"
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.import ip65_error
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.export tcp_init
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.export tcp_process
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.export tcp_connect
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.export tcp_callback
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.export tcp_connect_ip
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.export tcp_send_data_len
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.export tcp_send
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.export tcp_send_string
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.export tcp_close
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.export tcp_listen
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.export tcp_send_keep_alive
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.export tcp_connect_remote_port
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.export tcp_remote_ip
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.export tcp_state
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.export tcp_inbound_data_ptr
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.export tcp_inbound_data_length
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.import ip_calc_cksum
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.import ip_send
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.import ip_create_packet
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.import ip_inp
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.import ip_outp
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.import ip65_process
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.import check_for_abort_key
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.import timer_read
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.import ip65_random_word
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.importzp acc32
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.importzp op32
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.importzp acc16
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.import add_32_32
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.import add_16_32
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.import cmp_32_32
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.import cmp_16_16
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.import sub_16_16
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.importzp ip_cksum_ptr
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.importzp ip_header_cksum
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.importzp ip_src
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.importzp ip_dest
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.importzp ip_data
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.importzp ip_proto
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.importzp ip_proto_tcp
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.importzp ip_id
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.importzp ip_len
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.import copymem
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.importzp copy_src
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.importzp copy_dest
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.import cfg_ip
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tcp_cxn_state_closed = 0
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tcp_cxn_state_listening = 1 ; (waiting for an inbound SYN)
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tcp_cxn_state_syn_sent = 2 ; (waiting for an inbound SYN/ACK)
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tcp_cxn_state_established = 3
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; tcp packet offsets
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tcp_inp = ip_inp + ip_data ; pointer to tcp packet inside inbound ethernet frame
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tcp_outp = ip_outp + ip_data ; pointer to tcp packet inside outbound ethernet frame
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tcp_src_port = 0 ; offset of source port field in tcp packet
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tcp_dest_port = 2 ; offset of destination port field in tcp packet
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tcp_seq = 4 ; offset of sequence number field in tcp packet
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tcp_ack = 8 ; offset of acknowledgement field in tcp packet
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tcp_header_length = 12 ; offset of header length field in tcp packet
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tcp_flags_field = 13 ; offset of flags field in tcp packet
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tcp_window_size = 14 ; offset of window size field in tcp packet
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tcp_checksum = 16 ; offset of checksum field in tcp packet
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tcp_urgent_pointer = 18 ; offset of urgent pointer field in tcp packet
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tcp_data = 20 ; offset of data in tcp packet
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; virtual header
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tcp_vh = tcp_outp - 12
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tcp_vh_src = 0
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tcp_vh_dest = 4
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tcp_vh_zero = 8
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tcp_vh_proto = 9
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tcp_vh_len = 10
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tcp_flag_FIN = 1
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tcp_flag_SYN = 2
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tcp_flag_RST = 4
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tcp_flag_PSH = 8
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tcp_flag_ACK = 16
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tcp_flag_URG = 32
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.bss
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tcp_state: .res 1
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tcp_local_port: .res 2
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tcp_remote_port: .res 2
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tcp_remote_ip: .res 4
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tcp_sequence_number: .res 4
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tcp_ack_number: .res 4
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tcp_data_ptr: .res 2
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tcp_data_len: .res 2
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tcp_send_data_ptr: .res 2
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tcp_send_data_len: .res 2 ; length (in bytes) of data to be sent over tcp connection
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tcp_callback: .res 2 ; vector to routine to be called when data is received over tcp connection
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tcp_flags: .res 1
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tcp_fin_sent: .res 1
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tcp_listen_port: .res 2
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tcp_inbound_data_ptr: .res 2 ; pointer to data just recieved over tcp connection
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tcp_inbound_data_length: .res 2 ; length of data just received over tcp connection
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; (if this is $ffff, that means "end of file", i.e. remote end has closed connection)
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tcp_connect_sequence_number: .res 4 ; the seq number we will next send out
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tcp_connect_expected_ack_number: .res 4 ; what we expect to see in the next inbound ack
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tcp_connect_ack_number: .res 4 ; what we will next ack
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tcp_connect_last_received_seq_number: .res 4 ; the seq field in the last inbound packet for this connection
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tcp_connect_last_ack: .res 4 ; ack field in the last inbound packet for this connection
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tcp_connect_local_port: .res 2
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tcp_connect_remote_port: .res 2
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tcp_connect_ip: .res 4 ; ip address of remote server to connect to
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tcp_timer: .res 1
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tcp_loop_count: .res 1
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tcp_packet_sent_count: .res 1
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.code
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; initialize tcp
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; called automatically by ip_init if "ip.s" was compiled with -DTCP
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; inputs: none
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; outputs: none
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tcp_init:
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rts
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jmp_to_callback:
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jmp (tcp_callback)
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; listen for an inbound tcp connection
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; this is a 'blocking' call, i.e. it will not return until a connection has been made
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; inputs:
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; AX: destination port (2 bytes)
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; tcp_callback: vector to call when data arrives on this connection
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; outputs:
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; carry flag is set if an error occured, clear otherwise
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tcp_listen:
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stax tcp_listen_port
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lda #tcp_cxn_state_listening
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sta tcp_state
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lda #0 ; reset the "packet sent" counter
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sta tcp_packet_sent_count
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sta tcp_fin_sent
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; set the low word of seq number to $0000, high word to something random
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sta tcp_connect_sequence_number
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sta tcp_connect_sequence_number+1
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jsr ip65_random_word
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stax tcp_connect_sequence_number+2
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jsr set_expected_ack; ; due to various ugly hacks, the 'expected ack' value is now what is put into the 'SEQ' field in outbound packets
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@listen_loop:
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jsr ip65_process
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jsr check_for_abort_key
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bcc @no_abort
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lda #IP65_ERROR_ABORTED_BY_USER
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sta ip65_error
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rts
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@no_abort:
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lda #tcp_cxn_state_listening
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cmp tcp_state
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beq @listen_loop
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tcp_connection_established:
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; inc the sequence number to cover the SYN we have sent
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ldax #tcp_connect_sequence_number
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stax acc32
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ldax #$01
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jsr add_16_32
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set_expected_ack:
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; set the expected ack number with current seq number
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ldx #3
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: lda tcp_connect_sequence_number,x
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sta tcp_connect_expected_ack_number,x
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dex
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bpl :-
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rts
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; make outbound tcp connection
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; inputs:
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; tcp_connect_ip: destination ip address (4 bytes)
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; AX: destination port (2 bytes)
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; tcp_callback: vector to call when data arrives on this connection
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; outputs:
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; carry flag is set if an error occured, clear otherwise
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tcp_connect:
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stax tcp_connect_remote_port
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jsr ip65_random_word
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stax tcp_connect_local_port
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lda #tcp_cxn_state_syn_sent
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sta tcp_state
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lda #0 ; reset the "packet sent" counter
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sta tcp_packet_sent_count
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sta tcp_fin_sent
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; set the low word of seq number to $0000, high word to something random
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sta tcp_connect_sequence_number
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sta tcp_connect_sequence_number+1
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jsr ip65_random_word
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stax tcp_connect_sequence_number+2
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@tcp_polling_loop:
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; create a SYN packet
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lda #tcp_flag_SYN
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sta tcp_flags
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lda #0
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sta tcp_data_len
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sta tcp_data_len+1
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ldx #3
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: lda tcp_connect_ip,x
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sta tcp_remote_ip,x
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lda tcp_connect_sequence_number,x
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sta tcp_sequence_number,x
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dex
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bpl :-
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ldax tcp_connect_local_port
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stax tcp_local_port
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ldax tcp_connect_remote_port
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stax tcp_remote_port
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jsr tcp_send_packet
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lda tcp_packet_sent_count
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adc #1
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sta tcp_loop_count ; we wait a bit longer between each resend
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@outer_delay_loop:
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jsr timer_read
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stx tcp_timer ; we only care about the high byte
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@inner_delay_loop:
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jsr ip65_process
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jsr check_for_abort_key
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bcc @no_abort
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lda #IP65_ERROR_ABORTED_BY_USER
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sta ip65_error
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rts
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@no_abort:
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lda tcp_state
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cmp #tcp_cxn_state_syn_sent
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bne @got_a_response
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jsr timer_read
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cpx tcp_timer ; this will tick over after about 1/4 of a second
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beq @inner_delay_loop
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dec tcp_loop_count
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bne @outer_delay_loop
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inc tcp_packet_sent_count
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lda tcp_packet_sent_count
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cmp #MAX_TCP_PACKETS_SENT-1
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bpl @too_many_messages_sent
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jmp @tcp_polling_loop
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@too_many_messages_sent:
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@failed:
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lda #tcp_cxn_state_closed
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sta tcp_state
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lda #IP65_ERROR_TIMEOUT_ON_RECEIVE
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sta ip65_error
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sec ; signal an error
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rts
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@got_a_response:
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lda tcp_state
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cmp #tcp_cxn_state_closed
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bne @was_accepted
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sec ; if we got here, then the other side sent a RST or FIN, so signal an error to the caller
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rts
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@was_accepted:
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clc
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rts
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tcp_close:
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; close the current connection
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; inputs:
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; none
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; outputs:
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; carry flag is set if an error occured, clear otherwise
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lda tcp_state
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cmp #tcp_cxn_state_established
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beq :+
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@connection_closed:
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lda #tcp_cxn_state_closed
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sta tcp_state
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clc
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rts
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: ; increment the expected sequence number for the SYN we are about to send
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ldax #tcp_connect_expected_ack_number
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stax acc32
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ldax #1
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sta tcp_fin_sent
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jsr add_16_32
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@send_fin_loop:
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lda #tcp_flag_FIN+tcp_flag_ACK
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sta tcp_flags
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ldax #0
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stax tcp_data_len
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ldx #3
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: lda tcp_connect_ip,x
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sta tcp_remote_ip,x
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lda tcp_connect_ack_number,x
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sta tcp_ack_number,x
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lda tcp_connect_sequence_number,x
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sta tcp_sequence_number,x
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dex
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bpl :-
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ldax tcp_connect_local_port
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stax tcp_local_port
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ldax tcp_connect_remote_port
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stax tcp_remote_port
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jsr tcp_send_packet
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lda tcp_packet_sent_count
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adc #1
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sta tcp_loop_count ; we wait a bit longer between each resend
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@outer_delay_loop:
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jsr timer_read
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stx tcp_timer ; we only care about the high byte
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@inner_delay_loop:
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jsr ip65_process
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lda tcp_state
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cmp #tcp_cxn_state_established
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bne @connection_closed
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jsr timer_read
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cpx tcp_timer ; this will tick over after about 1/4 of a second
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beq @inner_delay_loop
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dec tcp_loop_count
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bne @outer_delay_loop
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inc tcp_packet_sent_count
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lda tcp_packet_sent_count
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cmp #MAX_TCP_PACKETS_SENT-1
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bpl @too_many_messages_sent
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jmp @send_fin_loop
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@too_many_messages_sent:
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@failed:
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lda #tcp_cxn_state_closed
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sta tcp_state
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lda #IP65_ERROR_TIMEOUT_ON_RECEIVE
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sta ip65_error
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sec ; signal an error
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rts
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; send a string over the current tcp connection
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; inputs:
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; tcp connection should already be opened
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; AX: pointer to buffer - data up to (but not including)
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; the first nul byte will be sent.
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; outputs:
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; carry flag is set if an error occured, clear otherwise
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tcp_send_string:
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stax tcp_send_data_ptr
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stax ptr1
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lda #0
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tay
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sta tcp_send_data_len
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sta tcp_send_data_len+1
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lda (ptr1),y
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bne @find_end_of_string
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rts ; if the string is empty, don't send anything!
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@find_end_of_string:
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lda (ptr1),y
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beq @done
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inc tcp_send_data_len
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iny
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bne @find_end_of_string
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inc tcp_send_data_len+1
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inc ptr1+1
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jmp @find_end_of_string
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@done:
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ldax tcp_send_data_ptr
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; now we can fall through into tcp_send
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; send tcp data
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; inputs:
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; tcp connection should already be opened
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; tcp_send_data_len: length of data to send (up to 1460 bytes)
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; AX: pointer to buffer containing data to be sent
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; outputs:
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; carry flag is set if an error occured, clear otherwise
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tcp_send:
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stax tcp_send_data_ptr
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lda tcp_state
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cmp #tcp_cxn_state_established
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beq @connection_established
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lda #IP65_ERROR_CONNECTION_CLOSED
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sta ip65_error
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sec
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rts
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lda #0 ; reset the "packet sent" counter
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sta tcp_packet_sent_count
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@connection_established:
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; increment the expected sequence number
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ldax #tcp_connect_expected_ack_number
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stax acc32
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ldax tcp_send_data_len
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jsr add_16_32
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@tcp_polling_loop:
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; create a data packet
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lda #tcp_flag_ACK+tcp_flag_PSH
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sta tcp_flags
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ldax tcp_send_data_len
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stax tcp_data_len
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ldax tcp_send_data_ptr
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stax tcp_data_ptr
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ldx #3
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: lda tcp_connect_ip,x
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sta tcp_remote_ip,x
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lda tcp_connect_sequence_number,x
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sta tcp_sequence_number,x
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dex
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bpl :-
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ldax tcp_connect_local_port
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stax tcp_local_port
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ldax tcp_connect_remote_port
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stax tcp_remote_port
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jsr tcp_send_packet
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lda tcp_packet_sent_count
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adc #1
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sta tcp_loop_count ; we wait a bit longer between each resend
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@outer_delay_loop:
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jsr timer_read
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stx tcp_timer ; we only care about the high byte
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@inner_delay_loop:
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jsr ip65_process
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jsr check_for_abort_key
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bcc @no_abort
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lda #IP65_ERROR_ABORTED_BY_USER
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sta ip65_error
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lda #tcp_cxn_state_closed
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sta tcp_state
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rts
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@no_abort:
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ldax #tcp_connect_last_ack
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stax acc32
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ldax #tcp_connect_expected_ack_number
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stax op32
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jsr cmp_32_32
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beq @got_ack
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jsr timer_read
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cpx tcp_timer ; this will tick over after about 1/4 of a second
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beq @inner_delay_loop
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dec tcp_loop_count
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bne @outer_delay_loop
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inc tcp_packet_sent_count
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lda tcp_packet_sent_count
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cmp #MAX_TCP_PACKETS_SENT-1
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bpl @too_many_messages_sent
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jmp @tcp_polling_loop
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@too_many_messages_sent:
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@failed:
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lda #tcp_cxn_state_closed
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sta tcp_state
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lda #IP65_ERROR_TIMEOUT_ON_RECEIVE
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sta ip65_error
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sec ; signal an error
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rts
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@got_ack:
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; finished - now we need to advance the sequence number for the data we just sent
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ldax #tcp_connect_sequence_number
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stax acc32
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ldax tcp_send_data_len
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jsr add_16_32
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clc
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rts
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|
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; send a single tcp packet
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; inputs:
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; tcp_remote_ip: IP address of destination server
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; tcp_remote_port: destination tcp port
|
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; tcp_local_port: source tcp port
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; tcp_flags: 6 bit flags
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; tcp_data_ptr: pointer to data to include in this packet
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; tcp_data_len: length of data pointed at by tcp_data_ptr
|
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; outputs:
|
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; carry flag is set if an error occured, clear otherwise
|
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tcp_send_packet:
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ldax tcp_data_ptr
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stax copy_src ; copy data to output buffer
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ldax #tcp_outp + tcp_data
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stax copy_dest
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ldax tcp_data_len
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jsr copymem
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ldx #3 ; copy virtual header addresses
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: lda tcp_remote_ip,x
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sta tcp_vh + tcp_vh_dest,x ; set virtual header destination
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lda cfg_ip,x
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sta tcp_vh + tcp_vh_src,x ; set virtual header source
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dex
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bpl :-
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lda tcp_local_port ; copy source port
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sta tcp_outp + tcp_src_port + 1
|
|
lda tcp_local_port + 1
|
|
sta tcp_outp + tcp_src_port
|
|
|
|
lda tcp_remote_port ; copy destination port
|
|
sta tcp_outp + tcp_dest_port + 1
|
|
lda tcp_remote_port + 1
|
|
sta tcp_outp + tcp_dest_port
|
|
|
|
ldx #3 ; copy sequence and ack (if ACK flag set) numbers (in reverse order)
|
|
ldy #0
|
|
: lda tcp_sequence_number,x
|
|
sta tcp_outp + tcp_seq,y
|
|
lda #tcp_flag_ACK
|
|
bit tcp_flags
|
|
bne @ack_set
|
|
lda #0
|
|
beq @sta_ack
|
|
@ack_set:
|
|
lda tcp_ack_number,x
|
|
@sta_ack:
|
|
sta tcp_outp + tcp_ack,y
|
|
iny
|
|
dex
|
|
bpl :-
|
|
|
|
lda #$50 ; 4 bit header length in 32bit words + 4 bits of zero
|
|
sta tcp_outp+tcp_header_length
|
|
lda tcp_flags
|
|
sta tcp_outp+tcp_flags_field
|
|
|
|
lda #ip_proto_tcp
|
|
sta tcp_vh + tcp_vh_proto
|
|
|
|
ldax #$b405 ; $05b4 (1460) in network byte order
|
|
stax tcp_outp+tcp_window_size
|
|
|
|
lda #0 ; clear checksum
|
|
sta tcp_outp + tcp_checksum
|
|
sta tcp_outp + tcp_checksum + 1
|
|
sta tcp_vh + tcp_vh_zero ; clear virtual header zero byte
|
|
|
|
ldax #tcp_vh ; checksum pointer to virtual header
|
|
stax ip_cksum_ptr
|
|
|
|
lda tcp_data_len ; copy length + 20
|
|
clc
|
|
adc #20
|
|
sta tcp_vh + tcp_vh_len + 1 ; lsb for virtual header
|
|
tay
|
|
lda tcp_data_len + 1
|
|
adc #0
|
|
sta tcp_vh + tcp_vh_len ; msb for virtual header
|
|
|
|
tax ; length to A/X
|
|
tya
|
|
|
|
clc ; add 12 bytes for virtual header
|
|
adc #12
|
|
bcc :+
|
|
inx
|
|
: jsr ip_calc_cksum ; calculate checksum
|
|
stax tcp_outp + tcp_checksum
|
|
|
|
ldx #3 ; copy addresses
|
|
: lda tcp_remote_ip,x
|
|
sta ip_outp + ip_dest,x ; set ip destination address
|
|
dex
|
|
bpl :-
|
|
|
|
jsr ip_create_packet ; create ip packet template
|
|
|
|
lda tcp_data_len ; ip len = tcp data length + 20 byte ip header + 20 byte tcp header
|
|
ldx tcp_data_len + 1
|
|
clc
|
|
adc #40
|
|
bcc :+
|
|
inx
|
|
: sta ip_outp + ip_len + 1 ; set length
|
|
stx ip_outp + ip_len
|
|
|
|
ldax #$1234 ; set ID
|
|
stax ip_outp + ip_id
|
|
|
|
lda #ip_proto_tcp ; set protocol
|
|
sta ip_outp + ip_proto
|
|
|
|
jmp ip_send ; send packet, sec on error
|
|
|
|
; see if the ip packet we just got is for a valid (non-closed) tcp connection
|
|
; inputs:
|
|
; eth_inp: should contain an ethernet frame encapsulating an inbound tcp packet
|
|
; outputs:
|
|
; carry flag clear if inbound tcp packet part of existing connection
|
|
check_current_connection:
|
|
lda tcp_state
|
|
cmp #tcp_cxn_state_closed
|
|
bne @connection_not_closed
|
|
sec
|
|
rts
|
|
@connection_not_closed:
|
|
ldax #ip_inp+ip_src
|
|
stax acc32
|
|
ldax #tcp_connect_ip
|
|
stax op32
|
|
jsr cmp_32_32
|
|
beq @remote_ip_matches
|
|
sec
|
|
rts
|
|
@remote_ip_matches:
|
|
ldax tcp_inp+tcp_src_port
|
|
stax acc16
|
|
lda tcp_connect_remote_port+1 ; this value in reverse byte order to how it is presented in the TCP header
|
|
ldx tcp_connect_remote_port
|
|
jsr cmp_16_16
|
|
beq @remote_port_matches
|
|
sec
|
|
rts
|
|
@remote_port_matches:
|
|
ldax tcp_inp+tcp_dest_port
|
|
stax acc16
|
|
lda tcp_connect_local_port+1 ; this value in reverse byte order to how it is presented in the TCP header
|
|
ldx tcp_connect_local_port
|
|
jsr cmp_16_16
|
|
beq @local_port_matches
|
|
sec
|
|
rts
|
|
@local_port_matches:
|
|
clc
|
|
rts
|
|
|
|
; process incoming tcp packet
|
|
; called automatically by ip_process if "ip.s" was compiled with -DTCP
|
|
; inputs:
|
|
; eth_inp: should contain an ethernet frame encapsulating an inbound tcp packet
|
|
; outputs:
|
|
; none but if connection was found, an outbound message may be created, overwriting eth_outp
|
|
; also tcp_state and other tcp variables may be modified
|
|
tcp_process:
|
|
lda #tcp_flag_RST
|
|
bit tcp_inp+tcp_flags_field
|
|
beq @not_reset
|
|
jsr check_current_connection
|
|
bcs @not_current_connection_on_rst
|
|
; for some reason, search.twitter.com is sending RSTs with ID=$1234 (i.e. echoing the inbound ID)
|
|
; but then keeps the connection open and ends up sending the file.
|
|
; so lets ignore a reset with ID=$1234
|
|
lda ip_inp+ip_id
|
|
cmp #$34
|
|
bne @not_invalid_reset
|
|
lda ip_inp+ip_id+1
|
|
cmp #$12
|
|
bne @not_invalid_reset
|
|
jmp @send_ack
|
|
@not_invalid_reset:
|
|
; connection has been reset so mark it as closed
|
|
lda #tcp_cxn_state_closed
|
|
sta tcp_state
|
|
lda #IP65_ERROR_CONNECTION_RESET_BY_PEER
|
|
sta ip65_error
|
|
|
|
lda #$ff
|
|
sta tcp_inbound_data_length
|
|
sta tcp_inbound_data_length+1
|
|
jsr jmp_to_callback ; let the caller see the connection has closed
|
|
|
|
@not_current_connection_on_rst:
|
|
; if we get a reset for a closed or nonexistent connection, then ignore it
|
|
rts
|
|
@not_reset:
|
|
lda tcp_inp+tcp_flags_field
|
|
cmp #tcp_flag_SYN+tcp_flag_ACK
|
|
bne @not_syn_ack
|
|
|
|
; it's a SYN/ACK
|
|
jsr check_current_connection
|
|
bcc @current_connection_on_syn_ack
|
|
; if we get a SYN/ACK for something that aint the connection we're expecting,
|
|
; terminate with extreme prejudice
|
|
jmp @send_rst
|
|
@current_connection_on_syn_ack:
|
|
lda tcp_state
|
|
cmp #tcp_cxn_state_syn_sent
|
|
bne @not_expecting_syn_ack
|
|
; this IS the syn/ack we are waiting for :-)
|
|
ldx #3 ; copy sequence number to ack (in reverse order)
|
|
ldy #0
|
|
: lda tcp_inp + tcp_seq,y
|
|
sta tcp_connect_ack_number,x
|
|
iny
|
|
dex
|
|
bpl :-
|
|
|
|
ldax #tcp_connect_ack_number
|
|
stax acc32
|
|
ldax #$0001
|
|
jsr add_16_32 ; increment the ACK counter by 1, for the SYN we just received
|
|
|
|
jsr tcp_connection_established
|
|
|
|
lda #tcp_cxn_state_established
|
|
sta tcp_state
|
|
|
|
@not_expecting_syn_ack:
|
|
; we get a SYN/ACK for the current connection,
|
|
; but we're not expecting it, it's probably
|
|
; a retransmist - just ACK it
|
|
jmp @send_ack
|
|
|
|
@not_syn_ack:
|
|
; is it an ACK - alone or with PSH/URGENT but not a SYN/ACK?
|
|
lda #tcp_flag_ACK
|
|
bit tcp_inp+tcp_flags_field
|
|
bne @ack
|
|
jmp @not_ack
|
|
@ack:
|
|
; is this the current connection?
|
|
jsr check_current_connection
|
|
bcc @current_connection_on_ack
|
|
; if we get an ACK for something that is not the current connection
|
|
; we should send a RST
|
|
jmp @send_rst
|
|
@current_connection_on_ack:
|
|
; if it's an ACK, then record the last ACK (reorder the bytes in the process)
|
|
ldx #3 ; copy seq & ack fields (in reverse order)
|
|
ldy #0
|
|
: lda tcp_inp + tcp_ack,y
|
|
sta tcp_connect_last_ack,x
|
|
lda tcp_inp + tcp_seq,y
|
|
sta tcp_connect_last_received_seq_number,x
|
|
iny
|
|
dex
|
|
bpl :-
|
|
|
|
; was this the next sequence number we're waiting for?
|
|
ldax #tcp_connect_ack_number
|
|
stax acc32
|
|
ldax #tcp_connect_last_received_seq_number
|
|
stax op32
|
|
jsr cmp_32_32
|
|
|
|
bne @not_expected_seq_number
|
|
|
|
; what is the size of data in this packet?
|
|
lda ip_inp+ip_len+1 ; payload length (lo byte)
|
|
sta acc16
|
|
lda ip_inp+ip_len ; payload length (hi byte)
|
|
sta acc16+1
|
|
lda tcp_inp+tcp_header_length ; high 4 bits is header length in 32 bit words
|
|
lsr ; A=A/2
|
|
lsr ; A=A/2
|
|
clc ; A now equal to tcp header length in bytes
|
|
adc #20 ; add 20 bytes for IP header, this gives length of IP +TCP headers
|
|
ldx #0
|
|
sta tcp_header_length
|
|
jsr sub_16_16
|
|
|
|
; acc16 now contains the length of data in this TCP packet
|
|
lda acc16
|
|
sta tcp_inbound_data_length
|
|
lda acc16+1
|
|
sta tcp_inbound_data_length+1
|
|
bne @not_empty_packet
|
|
lda acc16
|
|
bne @not_empty_packet
|
|
jmp @empty_packet
|
|
@not_empty_packet:
|
|
; calculate ptr to tcp data
|
|
clc
|
|
lda tcp_header_length
|
|
adc #<ip_inp
|
|
sta tcp_inbound_data_ptr
|
|
lda #>ip_inp
|
|
adc #0
|
|
sta tcp_inbound_data_ptr+1
|
|
|
|
; do a callback
|
|
jsr jmp_to_callback
|
|
|
|
; move ack ptr along
|
|
ldax #tcp_connect_ack_number
|
|
stax acc32
|
|
ldax tcp_inbound_data_length
|
|
jsr add_16_32
|
|
|
|
; send an ACK with the sequence number we expect
|
|
@not_expected_seq_number:
|
|
; send the ACK for any data in this packet, then return to check for FIN flag
|
|
jsr @send_ack
|
|
|
|
@not_ack:
|
|
@empty_packet:
|
|
; is it a FIN?
|
|
lda #tcp_flag_FIN
|
|
bit tcp_inp+tcp_flags_field
|
|
bne @fin
|
|
jmp @not_fin
|
|
@fin:
|
|
; is this the current connection?
|
|
jsr check_current_connection
|
|
bcc :+
|
|
jmp @send_rst ; reset if not current connection
|
|
: ldx #3 ; copy seq field (in reverse order)
|
|
ldy #0
|
|
: lda tcp_inp + tcp_seq,y
|
|
sta tcp_connect_last_received_seq_number,x
|
|
iny
|
|
dex
|
|
bpl :-
|
|
|
|
; was this the next sequence number we're waiting for?
|
|
ldax #tcp_connect_ack_number
|
|
stax acc32
|
|
ldax #tcp_connect_last_received_seq_number
|
|
stax op32
|
|
jsr cmp_32_32
|
|
|
|
beq :+
|
|
rts ; bail if not expected sequence number
|
|
: ; set the length to $ffff
|
|
lda #$ff
|
|
sta tcp_inbound_data_length
|
|
sta tcp_inbound_data_length+1
|
|
jsr jmp_to_callback ; let the caller see the connection has closed
|
|
|
|
lda #tcp_cxn_state_closed
|
|
sta tcp_state
|
|
|
|
; send a FIN/ACK
|
|
; move ack ptr along for the inbound FIN
|
|
ldax #tcp_connect_ack_number
|
|
stax acc32
|
|
ldax #$01
|
|
sta tcp_fin_sent
|
|
jsr add_16_32
|
|
|
|
; if we've already sent a FIN then just send back an ACK
|
|
lda tcp_fin_sent
|
|
beq @send_fin_ack
|
|
; if we get here, we've sent a FIN, and just received an inbound FIN.
|
|
; when we sent the fin, we didn't update the sequence number, since
|
|
; we want to use the old sequence on every resend of that FIN
|
|
; now that our fin has been ACKed, we need to inc the sequence number
|
|
; and then send another ACK.
|
|
|
|
ldax #tcp_connect_sequence_number
|
|
stax acc32
|
|
ldax #$0001
|
|
jsr add_16_32 ; increment the SEQ counter by 1, for the FIN we have been sending
|
|
|
|
lda #tcp_flag_ACK
|
|
jmp @send_packet
|
|
|
|
@send_fin_ack:
|
|
lda #tcp_flag_FIN+tcp_flag_ACK
|
|
jmp @send_packet
|
|
|
|
@not_fin:
|
|
lda tcp_inp+tcp_flags_field
|
|
cmp #tcp_flag_SYN
|
|
beq @syn
|
|
jmp @not_syn
|
|
@syn:
|
|
; is this the port we are listening on?
|
|
lda tcp_inp+tcp_dest_port+1
|
|
cmp tcp_listen_port
|
|
bne @decline_syn_with_reset
|
|
lda tcp_inp+tcp_dest_port
|
|
cmp tcp_listen_port+1
|
|
bne @decline_syn_with_reset
|
|
|
|
; it's the right port - are we actually waiting for a connecting?
|
|
lda #tcp_cxn_state_listening
|
|
cmp tcp_state
|
|
beq @this_is_connection_we_are_waiting_for
|
|
; is this the current connection? that would mean our ACK got lost, so resend
|
|
jsr check_current_connection
|
|
bcc @this_is_connection_we_are_waiting_for
|
|
rts ; if we've currently got a connection open, then ignore any new requests
|
|
; the sender will timeout and resend the SYN, by which time we may be
|
|
; ready to accept it again.
|
|
|
|
@this_is_connection_we_are_waiting_for:
|
|
; copy sequence number to ack (in reverse order) and remote IP
|
|
ldx #3
|
|
ldy #0
|
|
: lda tcp_inp + tcp_seq,y
|
|
sta tcp_connect_ack_number,x
|
|
lda ip_inp+ip_src,x
|
|
sta tcp_connect_ip,x
|
|
iny
|
|
dex
|
|
bpl :-
|
|
|
|
; copy ports
|
|
ldax tcp_listen_port
|
|
stax tcp_connect_local_port
|
|
|
|
lda tcp_inp+tcp_src_port+1
|
|
sta tcp_connect_remote_port
|
|
lda tcp_inp+tcp_src_port
|
|
sta tcp_connect_remote_port+1
|
|
|
|
lda #tcp_cxn_state_established
|
|
sta tcp_state
|
|
|
|
ldax #tcp_connect_ack_number
|
|
stax acc32
|
|
ldax #$0001
|
|
jsr add_16_32 ; increment the ACK counter by 1, for the SYN we just received
|
|
lda #tcp_flag_SYN+tcp_flag_ACK
|
|
jmp @send_packet
|
|
|
|
@decline_syn_with_reset:
|
|
; create a RST packet
|
|
ldx #3 ; copy sequence number to ack (in reverse order)
|
|
ldy #0
|
|
: lda tcp_inp + tcp_seq,y
|
|
sta tcp_ack_number,x
|
|
iny
|
|
dex
|
|
bpl :-
|
|
|
|
ldax #tcp_ack_number
|
|
stax acc32
|
|
ldax #$0001
|
|
jsr add_16_32 ; increment the ACK counter by 1, for the SYN we just received
|
|
|
|
@send_rst:
|
|
lda #tcp_flag_RST+tcp_flag_ACK
|
|
sta tcp_flags
|
|
ldax #0
|
|
stax tcp_data_len
|
|
ldx #3
|
|
: lda ip_inp+ip_src,x
|
|
sta tcp_remote_ip,x
|
|
dex
|
|
bpl :-
|
|
|
|
; copy src/dest ports in inverted byte order
|
|
lda tcp_inp+tcp_src_port
|
|
sta tcp_remote_port+1
|
|
lda tcp_inp+tcp_src_port+1
|
|
sta tcp_remote_port
|
|
|
|
lda tcp_inp+tcp_dest_port
|
|
sta tcp_local_port+1
|
|
lda tcp_inp+tcp_dest_port+1
|
|
sta tcp_local_port
|
|
|
|
jsr tcp_send_packet
|
|
|
|
@not_syn:
|
|
rts
|
|
|
|
@send_ack:
|
|
; create an ACK packet
|
|
lda #tcp_flag_ACK
|
|
|
|
@send_packet:
|
|
sta tcp_flags
|
|
ldax #0
|
|
stax tcp_data_len
|
|
ldx #3
|
|
: lda tcp_connect_ip,x
|
|
sta tcp_remote_ip,x
|
|
lda tcp_connect_ack_number,x
|
|
sta tcp_ack_number,x
|
|
; if we have just sent a packet out, we may not yet have updated tcp_connect_sequence_number yet
|
|
; so use current value of tcp_connect_expected_ack_number as outbound sequence number instead
|
|
lda tcp_connect_expected_ack_number,x
|
|
sta tcp_sequence_number,x
|
|
dex
|
|
bpl :-
|
|
ldax tcp_connect_local_port
|
|
stax tcp_local_port
|
|
ldax tcp_connect_remote_port
|
|
stax tcp_remote_port
|
|
|
|
jmp tcp_send_packet
|
|
|
|
; send an empty ACK packet on the current connection
|
|
; inputs:
|
|
; none
|
|
; outputs:
|
|
; carry flag is set if an error occured, clear otherwise
|
|
tcp_send_keep_alive = @send_ack
|
|
|
|
|
|
|
|
; -- LICENSE FOR tcp.s --
|
|
; The contents of this file are subject to the Mozilla Public License
|
|
; Version 1.1 (the "License"); you may not use this file except in
|
|
; compliance with the License. You may obtain a copy of the License at
|
|
; http://www.mozilla.org/MPL/
|
|
;
|
|
; Software distributed under the License is distributed on an "AS IS"
|
|
; basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
|
|
; License for the specific language governing rights and limitations
|
|
; under the License.
|
|
;
|
|
; The Original Code is ip65.
|
|
;
|
|
; The Initial Developer of the Original Code is Jonno Downes,
|
|
; jonno@jamtronix.com.
|
|
; Portions created by the Initial Developer are Copyright (C) 2009
|
|
; Jonno Downes. All Rights Reserved.
|
|
; -- LICENSE END --
|