emailler/ip65/ip.s

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.include "zeropage.inc"
.include "../inc/common.inc"
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.export ip_init
.export ip_process
.export ip_calc_cksum
.export ip_create_packet
.export ip_send
.export ip_inp
.export ip_outp
.export ip_broadcast
.exportzp ip_ver_ihl
.exportzp ip_tos
.exportzp ip_len
.exportzp ip_id
.exportzp ip_frag
.exportzp ip_ttl
.exportzp ip_proto
.exportzp ip_header_cksum
.exportzp ip_src
.exportzp ip_dest
.exportzp ip_data
.exportzp ip_proto_icmp
.exportzp ip_proto_tcp
.exportzp ip_proto_udp
.import cfg_mac
.import cfg_ip
.import eth_tx
.import eth_set_proto
.import eth_inp
.import eth_inp_len
.import eth_outp
.import eth_outp_len
.importzp eth_dest
.importzp eth_src
.importzp eth_type
.importzp eth_data
.importzp eth_proto_ip
.importzp eth_proto_arp
.import arp_lookup
.import arp_mac
.import arp_ip
.import icmp_init
.import icmp_process
.import udp_init
.import udp_process
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.ifdef TCP
.import tcp_init
.import tcp_process
.endif
.exportzp ip_cksum_ptr = ptr2
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.bss
ip_cksum_len: .res 2 ; length of data to be checksummed
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; ip packets start at ethernet packet + 14
ip_inp = eth_inp + eth_data ; pointer to start of IP packet in input ethernet frame
ip_outp = eth_outp + eth_data ; pointer to start of IP packet in output ethernet frame
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; temp storage for size calculation
len: .res 2
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; flag for incoming broadcast packets
ip_broadcast: .res 1 ; flag set when an incoming IP packet was sent to a broadcast address
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; ip packet offsets
ip_ver_ihl = 0 ; offset of 4 bit "version" field and 4 bit "header length" field in an IP packet header
ip_tos = 1 ; offset of "type of service" field in an IP packet header
ip_len = 2 ; offset of "length" field in an IP packet header
ip_id = 4 ; offset of "identification" field in an IP packet header
ip_frag = 6 ; offset of "fragmentation offset" field in an IP packet header
ip_ttl = 8 ; offset of "time to live" field in an IP packet header
ip_proto = 9 ; offset of "protocol number" field in an IP packet header
ip_header_cksum = 10 ; offset of "ip header checksum" field in an IP packet header
ip_src = 12 ; offset of "source address" field in an IP packet header
ip_dest = 16 ; offset of "destination address" field in an IP packet header
ip_data = 20 ; offset of data payload in an IP packet
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; ip protocols
ip_proto_icmp = 1
ip_proto_tcp = 6
ip_proto_udp = 17
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; temp for calculating checksum
cksum: .res 3
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; bad packet counters
bad_header: .res 2
bad_addr: .res 2
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.code
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; initialize ip routines
; inputs: none
; outputs: none
ip_init:
lda #0
sta bad_header
sta bad_header + 1
sta bad_addr
sta bad_addr + 1
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jsr icmp_init
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.ifdef TCP
jsr tcp_init
.endif
jsr udp_init
rts
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; process an incoming packet & call the appropriate protocol handler
; inputs:
; eth_inp: should point to the received ethernet packet
; outputs:
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; carry flag - set on any error, clear if OK
; depending on the packet contents and the protocol handler, a response
; message may be generated and sent out (overwriting eth_outp buffer)
ip_process:
jsr verifyheader ; ver, ihl, len, frag, checksum
bcc @ok
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@badpacket:
sec
rts
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@ok:
jsr checkaddr ; make sure it's meant for us
bcs @badpacket
lda ip_inp + ip_proto
cmp #ip_proto_icmp
bne :+
jmp icmp_process ; jump to icmp handler
.ifdef TCP
: cmp #ip_proto_tcp
bne :+
jmp tcp_process ; jump to tcp handler
.endif
: cmp #ip_proto_udp
bne :+
jmp udp_process ; jump to udp handler
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:
unknown_protocol:
sec ; unknown protocol
rts
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; verify that header contains what we expect
verifyheader:
lda ip_inp + ip_ver_ihl ; IPv4 and no IP options
cmp #$45
bne @badpacket
; lda ip_inp + ip_tos ; ignore ToS
lda ip_inp + ip_len + 1 ; ip + 14 bytes ethernet header
clc
adc #14
sta len
lda ip_inp + ip_len
adc #0
sta len + 1
lda eth_inp_len ; check if advertised length is shorter
sec ; than actual length
sbc len
lda eth_inp_len + 1
sbc len + 1
bmi @badpacket
lda ip_inp + ip_frag ; check for fragmentation
beq :+
cmp #$40
bne @badpacket
: lda ip_inp + ip_frag + 1
bne @badpacket
; it is possible that the checksum has not been set in inbound packets
; this is especially likely to happen if we are running in an emulator on a host machine that
; does checksum offloading (i.e. where the NIC calculates the checksum) and then
; try to send traffic from the host to the emulated computer (e.g. ip65 running on AppleWin or VICE)
; in this case the traffic will be seen by the emulated computer BEFORE the host NIC
; has calculated the checksum
; so if the checksum field in the inbound packet is 0000, ignore it
lda ip_inp+10
bne @has_cksum
lda ip_inp+11
bne @has_cksum
clc
rts
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@has_cksum:
ldax #ip_inp ; verify checksum
stax ip_cksum_ptr
ldax #20
jsr ip_calc_cksum
cmp #0
bne @badpacket
cpx #0
bne @badpacket
clc
rts
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@badpacket:
inc bad_header
bne :+
inc bad_header + 1
: sec
rts
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; check that this packet was addressed to us
checkaddr:
lda #0
sta ip_broadcast
lda ip_inp + ip_dest ; compare ip address
cmp cfg_ip
bne @broadcast
lda ip_inp + ip_dest + 1
cmp cfg_ip + 1
bne @broadcast
lda ip_inp + ip_dest + 2
cmp cfg_ip + 2
bne @broadcast
lda ip_inp + ip_dest + 3
cmp cfg_ip + 3
bne @broadcast
@ok:
clc
rts
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@broadcast:
; jonno 2011-01-2
; previously this was just checking for 255.255.255.255
; however it is also possible to do a broadcast to a specific subnet, e.g. 10.5.1.255
; this is particularly common with NETBIOS over TCP
; we really should use the netmask, but as a kludge, just see if last octet is 255.
; this will work on a /24 network
inc ip_broadcast
; lda ip_inp + ip_dest ; check for broadcast
; and ip_inp + ip_dest + 1
; and ip_inp + ip_dest + 2
; and ip_inp + ip_dest + 3
lda ip_inp + ip_dest +3 ; check for broadcast
cmp #$ff
beq @ok
inc bad_addr
bne :+
inc bad_addr + 1
: sec
rts
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; create an IP header (with all the appropriate flags and common fields set) inside an
; ethernet frame
; inputs:
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; eth_outp: should point to a buffer in which the ethernet frame is being built
; outputs:
; eth_outp: contains an IP header with version, TTL, flags, src address & IP header
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; checksum fields set.
ip_create_packet:
lda #$45 ; set IP version and header length
sta ip_outp + ip_ver_ihl
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lda #0 ; set type of service
sta ip_outp + ip_tos
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; skip length
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; skip ID
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lda #$40 ; don't fragment - or should we not care?
sta ip_outp + ip_frag
lda #0
sta ip_outp + ip_frag + 1
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lda #$40 ; set time to live
sta ip_outp + ip_ttl
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; skip protocol
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lda #0 ; clear checksum
sta ip_outp + ip_header_cksum
sta ip_outp + ip_header_cksum + 1
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ldx #3 ; copy source address
: lda cfg_ip,x
sta ip_outp + ip_src,x
dex
bpl :-
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; skip destination address
rts
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; send an IP packet
; inputs
; eth_outp: should point to an ethernet frame that has an IP header created (by
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; calling ip_create_packet)
; ip_len: should contain length of IP packet (header + data)
; ip_id: should contain an ID that is unique for each packet
; ip_protocol: should contain protocol ID
; ip_dest: should contain the destination IP address
; outputs:
; eth_outp: ethernet frame updated with correct IP header, then sent out over
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; the wire
; carry flag - set on any error, clear if OK
ip_send:
ldx #3 ; get mac addr from ip
: lda ip_outp + ip_dest,x
sta arp_ip,x
dex
bpl :-
jsr arp_lookup
bcc :+
rts ; packet buffer nuked, fail
: ldax #ip_outp ; calculate ip header checksum
stax ip_cksum_ptr
ldax #20
jsr ip_calc_cksum
stax ip_outp + ip_header_cksum
ldx #5
: lda arp_mac,x ; copy destination mac address
sta eth_outp + eth_dest,x
lda cfg_mac,x ; copy my mac address
sta eth_outp + eth_src,x
dex
bpl :-
lda #eth_proto_ip ; set type to IP
jsr eth_set_proto
lda ip_outp + ip_len + 1 ; set packet length
lsr
bcc @dontpad
rol ; pad with 0
; clc
adc #<ip_outp
sta ptr1
lda ip_outp + ip_len
adc #>ip_outp
sta ptr1 + 1
ldy #0
tya
sta (ptr1),y
sec ; round up to even number
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@dontpad:
lda ip_outp + ip_len + 1
adc #eth_data
sta eth_outp_len
lda ip_outp + ip_len
adc #0
sta eth_outp_len + 1
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jmp eth_tx ; send packet and return status
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; calculate checksum for a buffer according to the standard IP checksum algorithm
; David Schmidt discovered errors in the original ip65 implementation, and he replaced
; this with an implementation from the contiki project (http://www.sics.se/contiki/)
; when incorporating ip65 into ADTPro (http://adtpro.sourceforge.net/)
; So I have cribbed that version from
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; http://adtpro.cvs.sourceforge.net/viewvc/adtpro/adtpro/client/src/ip65/ip.s
; inputs:
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; ip_cksum_ptr: points at buffer to be checksummed
; AX: length of buffer to be checksumed
; outputs:
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; AX: checkum of buffer
ip_calc_cksum:
sta ip_cksum_len ; save length
stx ip_cksum_len + 1
lda #0
sta cksum
sta cksum+1
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lda ip_cksum_len+1
beq chksumlast
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; If checksum is > 256, do the first runs.
ldy #0
clc
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chksumloop_256:
lda (ip_cksum_ptr),y
adc cksum
sta cksum
iny
lda (ip_cksum_ptr),y
adc cksum+1
sta cksum+1
iny
bne chksumloop_256
inc ip_cksum_ptr+1
dec ip_cksum_len+1
bne chksumloop_256
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chksum_endloop_256:
lda cksum
adc #0
sta cksum
lda cksum+1
adc #0
sta cksum+1
bcs chksum_endloop_256
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chksumlast:
lda ip_cksum_len
lsr
bcc chksum_noodd
ldy ip_cksum_len
dey
lda (ip_cksum_ptr),y
clc
adc cksum
sta cksum
bcc noinc1
inc cksum+1
bne noinc1
inc cksum
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noinc1:
dec ip_cksum_len
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chksum_noodd:
clc
php
ldy ip_cksum_len
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chksum_loop1:
cpy #0
beq chksum_loop1_end
plp
dey
dey
lda (ip_cksum_ptr),y
adc cksum
sta cksum
iny
lda (ip_cksum_ptr),y
adc cksum+1
sta cksum+1
dey
php
jmp chksum_loop1
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chksum_loop1_end:
plp
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chksum_endloop:
lda cksum
adc #0
sta cksum
lda cksum+1
adc #0
sta cksum+1
bcs chksum_endloop
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lda cksum+1
eor #$ff
tax
lda cksum
eor #$ff
rts
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; -- LICENSE FOR ip.s --
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; 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/
;
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; 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.
;
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; The Original Code is ip65.
;
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; The Initial Developer of the Original Code is Per Olofsson,
; MagerValp@gmail.com.
; Portions created by the Initial Developer are Copyright (C) 2009
; Per Olofsson. All Rights Reserved.
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; -- LICENSE END --