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https://github.com/bobbimanners/emailler.git
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449 lines
10 KiB
ArmAsm
449 lines
10 KiB
ArmAsm
;########################
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; minimal dhcp implementation
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; written by jonno@jamtronix.com 2009
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;
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;########################
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; to use - first call ip65_init, then call dhcp_init
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; no inputs required.
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; on return, carry flag clear means IP config has been
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; sucesfully obtained (cfg_ip, cfg_netmask, cfg_gateway and cfg_dns set as appropriate).
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; if carry flag is set, IP config could not be set. that could be because of a network
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; error or because there was no response from a DHCP server within about 5 seconds.
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;########################
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MAX_DHCP_MESSAGES_SENT=12 ;timeout after sending 12 messages will be about 15 seconds (1+2+3...)/4
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.include "../inc/common.i"
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.export dhcp_init
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.export dhcp_server
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.export dhcp_state
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.import cfg_mac
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.import cfg_ip
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.import cfg_netmask
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.import cfg_gateway
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.import cfg_dns
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.import arp_init
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.import ip65_process
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.import udp_add_listener
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.import udp_remove_listener
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.import udp_callback
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.import udp_send
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.import udp_inp
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.importzp udp_data
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.import udp_send_dest
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.import udp_send_src_port
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.import udp_send_dest_port
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.import udp_send_len
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.import timer_read
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.bss
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; dhcp packet offsets
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dhcp_inp = udp_inp + udp_data
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dhcp_outp: .res 576
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dhcp_op = 0
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dhcp_htype = 1
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dhcp_hlen = 2
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dhcp_hops = 3
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dhcp_xid = 4
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dhcp_secs = 8
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dhcp_flags = 10
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dhcp_ciaddr = 12
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dhcp_yiaddr = 16
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dhcp_siaddr = 20
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dhcp_giaddr = 24
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dhcp_chaddr =28
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dhcp_sname = 44
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dhcp_file=108
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dhcp_cookie=236
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dhcp_options=240
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dhcp_server_port=67
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dhcp_client_port=68
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; dhcp state machine
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dhcp_initializing = 1 ; initial state
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dhcp_selecting = 2 ; sent a DHCPDISCOVER, waiting for a DHCPOFFER
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dhcp_ready_to_request = 3 ; got a DHCPOFFER, ready to send a DHCPREQUEST
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dhcp_requesting = 4 ; sent a DHCPREQUEST, waiting for a DHCPACK
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dhcp_bound = 5 ; we have been allocated an IP address
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dhcp_state: .res 1 ; current activity
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dhcp_message_sent_count: .res 1
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dhcp_timer: .res 1
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dhcp_loop_count: .res 1
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dhcp_break_polling_loop: .res 1
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dhcp_server: .res 4
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;DHCP constants
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BOOTREQUEST =1
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BOOTREPLY =2
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DHCPDISCOVER =1
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DHCPOFFER =2
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DHCPREQUEST =3
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DHCPDECLINE =4
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DHCPACK =5
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DHCPNAK =6
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DHCPRELEASE =7
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DHCPINFORM =8
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.code
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dhcp_init:
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ldx #3 ; rewrite ip address
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lda #0
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: sta cfg_ip,x
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dex
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bpl :-
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lda #dhcp_initializing
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sta dhcp_state
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ldax #dhcp_in
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stax udp_callback
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ldax #dhcp_client_port
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jsr udp_add_listener
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bcc :+
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rts
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:
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lda #0 ;reset the "message sent" counter
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sta dhcp_message_sent_count
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jsr send_dhcpdiscover
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@dhcp_polling_loop:
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lda dhcp_message_sent_count
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adc #1
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sta dhcp_loop_count ;we wait a bit longer between each resend
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@outer_delay_loop:
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lda #0
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sta dhcp_break_polling_loop
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jsr timer_read
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stx dhcp_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 #0
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cmp dhcp_break_polling_loop
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bne @break_polling_loop
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jsr timer_read
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cpx dhcp_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 dhcp_loop_count
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bne @outer_delay_loop
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@break_polling_loop:
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inc dhcp_message_sent_count
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lda dhcp_message_sent_count
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cmp #MAX_DHCP_MESSAGES_SENT-1
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bpl @too_many_messages_sent
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lda dhcp_state
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cmp #dhcp_initializing
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beq @initializing
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cmp #dhcp_selecting
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beq @selecting
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cmp #dhcp_ready_to_request
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beq @ready_to_request
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cmp #dhcp_bound
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beq @bound
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jmp @dhcp_polling_loop
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@initializing:
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@selecting:
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jsr send_dhcpdiscover
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jmp @dhcp_polling_loop
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@ready_to_request:
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jsr send_dhcprequest
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jmp @dhcp_polling_loop
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@bound:
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ldax #dhcp_client_port
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jsr udp_remove_listener
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rts
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@too_many_messages_sent:
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sec ;signal an error
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rts
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dhcp_create_request_msg:
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lda #BOOTREQUEST
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sta dhcp_outp+dhcp_op
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lda #1 ;htype 1 = "10 MB ethernet"
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sta dhcp_outp+dhcp_htype
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lda #6 ;ethernet MACs are 6 bytes
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sta dhcp_outp+dhcp_hlen
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lda #0 ;hops = 0
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sta dhcp_outp+dhcp_hops
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ldx #3 ;set xid to be "1234"
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clc
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: txa
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adc #01
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sta dhcp_outp+dhcp_xid,x
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dex
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bpl :-
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lda #0 ;secs =00
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sta dhcp_outp+dhcp_secs
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sta dhcp_outp+dhcp_secs+1
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;initially turn off all flags
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sta dhcp_outp+dhcp_flags
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sta dhcp_outp+dhcp_flags+1
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ldx #$0F ;set ciaddr to 0.0.0.0
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;set yiaddr to 0.0.0.0
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;set siaddr to 0.0.0.0
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;set giaddr to 0.0.0.0
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: sta dhcp_outp+dhcp_ciaddr,x
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dex
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bpl :-
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ldx #5 ;set chaddr to mac
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: lda cfg_mac,x
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sta dhcp_outp+dhcp_chaddr,x
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dex
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bpl :-
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ldx #192 ;set sname & file both to null
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lda #0
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: sta dhcp_outp+dhcp_sname-1,x
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dex
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bne :-
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lda #$63 ;copy the magic cookie
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sta dhcp_outp+dhcp_cookie+0
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lda #$82
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sta dhcp_outp+dhcp_cookie+1
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lda #$53
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sta dhcp_outp+dhcp_cookie+2
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lda #$63
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sta dhcp_outp+dhcp_cookie+3
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ldax #dhcp_client_port ; set source port
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stax udp_send_src_port
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ldax #dhcp_server_port ; set destination port
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stax udp_send_dest_port
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rts
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send_dhcpdiscover:
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lda #dhcp_initializing
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sta dhcp_state
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jsr dhcp_create_request_msg
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lda #$80 ;broadcast flag =1, all other bits 0
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sta dhcp_outp+dhcp_flags
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lda #53 ;option 53 - DHCP message type
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sta dhcp_outp+dhcp_options+0
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lda #1 ;option length is 1
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sta dhcp_outp+dhcp_options+1
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lda #DHCPDISCOVER
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sta dhcp_outp+dhcp_options+2
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lda #$FF ;option FF = end of options
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sta dhcp_outp+dhcp_options+3
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ldx #3 ; set destination address
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lda #$FF ; des = 255.255.255.255 (broadcast)
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: sta udp_send_dest,x
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dex
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bpl :-
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ldax #dhcp_options+4
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stax udp_send_len
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ldax #dhcp_outp
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jsr udp_send
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bcc :+
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rts
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: lda #dhcp_selecting
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sta dhcp_state
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rts
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;got a message on port 68
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dhcp_in:
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lda dhcp_inp+dhcp_op
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cmp #BOOTREPLY
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beq :+
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rts ;it's not what we were expecting
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:
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lda #0
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cmp dhcp_inp+dhcp_yiaddr ;is the first byte in the assigned address 0?
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bne :+
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rts ;if so, it's a bogus response - ignore
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:
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ldx #4 ;copy the our new IP address
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:
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lda dhcp_inp+dhcp_yiaddr,x
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sta cfg_ip,x
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dex
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bpl :-
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ldx #0
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@unpack_dhcp_options:
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lda dhcp_inp+dhcp_options,x
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cmp #$ff
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bne :+
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jmp @finished_unpacking_dhcp_options
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:
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cmp #53 ;is this field DHCP message type?
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bne @not_dhcp_message_type
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jmp @get_next_option
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lda dhcp_inp+dhcp_options+2,x
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cmp #DHCPOFFER ;if it's not a DHCP OFFER message, then stop processing
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beq :+
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rts
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: jmp @get_next_option
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@not_dhcp_message_type:
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cmp #1 ;option 1 is netmask
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bne @not_netmask
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lda dhcp_inp+dhcp_options+2,x
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sta cfg_netmask
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lda dhcp_inp+dhcp_options+3,x
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sta cfg_netmask+1
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lda dhcp_inp+dhcp_options+4,x
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sta cfg_netmask+2
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lda dhcp_inp+dhcp_options+5,x
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sta cfg_netmask+3
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jmp @get_next_option
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@not_netmask:
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cmp #3 ;option 3 is gateway
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bne @not_gateway
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lda dhcp_inp+dhcp_options+2,x
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sta cfg_gateway
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lda dhcp_inp+dhcp_options+3,x
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sta cfg_gateway+1
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lda dhcp_inp+dhcp_options+4,x
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sta cfg_gateway+2
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lda dhcp_inp+dhcp_options+5,x
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sta cfg_gateway+3
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jmp @get_next_option
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@not_gateway:
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cmp #6 ;option 3 6 is dns server
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bne @not_dns_server
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lda dhcp_inp+dhcp_options+2,x
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sta cfg_dns
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lda dhcp_inp+dhcp_options+3,x
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sta cfg_dns+1
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lda dhcp_inp+dhcp_options+4,x
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sta cfg_dns+2
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lda dhcp_inp+dhcp_options+5,x
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sta cfg_dns+3
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jmp @get_next_option
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@not_dns_server:
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cmp #54 ;option 54 is DHCP server
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bne @not_server
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lda dhcp_inp+dhcp_options+2,x
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sta dhcp_server
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lda dhcp_inp+dhcp_options+3,x
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sta dhcp_server+1
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lda dhcp_inp+dhcp_options+4,x
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sta dhcp_server+2
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lda dhcp_inp+dhcp_options+5,x
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sta dhcp_server+3
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jmp @get_next_option
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@not_server:
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@get_next_option:
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txa
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clc
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adc #02
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adc dhcp_inp+dhcp_options+1,x
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bcs @finished_unpacking_dhcp_options ; if we overflow, then we're done
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tax
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jmp @unpack_dhcp_options
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@finished_unpacking_dhcp_options:
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jsr arp_init ;we have modified our netmask, so we need to recalculate gw_test
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lda dhcp_state
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cmp #dhcp_bound
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beq :+
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lda #dhcp_ready_to_request
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sta dhcp_state
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:
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lda #1
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sta dhcp_break_polling_loop
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rts
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send_dhcprequest:
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jsr dhcp_create_request_msg
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lda #53 ;option 53 - DHCP message type
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sta dhcp_outp+dhcp_options+0
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lda #1 ;option length is 1
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sta dhcp_outp+dhcp_options+1
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lda #DHCPREQUEST
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sta dhcp_outp+dhcp_options+2
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lda #50 ;option 50 - requested IP address
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sta dhcp_outp+dhcp_options+3
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ldx #4 ;option length is 4
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stx dhcp_outp+dhcp_options+4
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dex
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: lda cfg_ip,x
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sta dhcp_outp+dhcp_options+5,x
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dex
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bpl :-
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lda #54 ;option 54 - DHCP server
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sta dhcp_outp+dhcp_options+9
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ldx #4 ;option length is 4
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stx dhcp_outp+dhcp_options+10
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dex
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: lda dhcp_server,x
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sta dhcp_outp+dhcp_options+11,x
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sta udp_send_dest,x
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dex
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bpl :-
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lda #$FF ;option FF = end of options
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sta dhcp_outp+dhcp_options+17
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ldax #dhcp_options+18
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stax udp_send_len
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ldax #dhcp_outp
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jsr udp_send
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bcs :+ ;if we didn't send the message we probably need to wait for an ARP reply to come back.
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lda #dhcp_bound ;technically, we should wait till we get a DHCPACK message. but we'll assume success
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sta dhcp_state
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:
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rts
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