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<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"/><link rel="stylesheet" type="text/css" href="ca65-doc-style.css"/></head><body><a href="ref_index.html"><h1>ip65 technical reference</h1></a><h1>File : ip65/ip.s</h1><h2 id="functions">functions</h2><table><tr><th>function</th><th>description</th></tr><tr><td id="ip_calc_cksum">ip_calc_cksum</td><td><pre> 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
http://adtpro.cvs.sourceforge.net/viewvc/adtpro/adtpro/client/src/ip65/ip.s
inputs:
ip_cksum_ptr: points at buffer to be checksummed
AX: length of buffer to be checksumed
outputs:
AX: checkum of buffer </pre></td></tr><tr><td id="ip_create_packet">ip_create_packet</td><td><pre> create an IP header (with all the appropriate flags and common fields set) inside an
ethernet frame
inputs:
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 &amp; IP header
checksum fields set. </pre></td></tr><tr><td id="ip_init">ip_init</td><td><pre> initialize ip routines
inputs: none
outputs: none </pre></td></tr><tr><td id="ip_process">ip_process</td><td><pre>process an incoming packet &amp; call the appropriate protocol handler
inputs:
eth_inp: should point to the received ethernet packet
outputs:
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) </pre></td></tr><tr><td id="ip_send">ip_send</td><td><pre> send an IP packet
inputs
eth_outp: should point to an ethernet frame that has an IP header created (by
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
the wire
carry flag - set on any error, clear if OK </pre></td></tr></table><h2 id="variables">variables</h2><table><tr><th>variable</th><th>description</th><th>size (bytes)</th></tr><tr><td id="ip_broadcast">ip_broadcast</td><td>flag set when an incoming IP packet was sent to a broadcast address </td><td>1</td></tr><tr><td id="ip_cksum_ptr">ip_cksum_ptr</td><td> pointer to data to be checksummed </td><td>2</td></tr></table><h2 id="constants">constants</h2><table><tr><th>constants</th><th>description</th><th>value</th></tr><tr><td id="ip_data">ip_data</td><td>offset of data payload in an IP packet </td><td>20 </td></tr><tr><td id="ip_dest">ip_dest</td><td>offset of "destination address" field in an IP packet header </td><td>16 </td></tr><tr><td id="ip_frag">ip_frag</td><td>offset of "fragmentation offset" field in an IP packet header </td><td>6 </td></tr><tr><td id="ip_header_cksum">ip_header_cksum</td><td>offset of "ip header checksum" field in an IP packet header </td><td>10 </td></tr><tr><td id="ip_id">ip_id</td><td>offset of "identification" field in an IP packet header </td><td>4 </td></tr><tr><td id="ip_inp">ip_inp</td><td>pointer to start of IP packet in input ethernet frame </td><td>eth_inp + eth_data </td></tr><tr><td id="ip_len">ip_len</td><td>offset of "length" field in an IP packet header </td><td>2 </td></tr><tr><td id="ip_outp">ip_outp</td><td>pointer to start of IP packet in output ethernet frame </td><td>eth_outp + eth_data </td></tr><tr><td id="ip_proto">ip_proto</td><td>offset of "protocol number" field in an IP packet header </td><td>9 </td></tr><tr><td id="ip_proto_icmp">ip_proto_icmp</td><td> ip protocols </td><td>1
</td></tr><tr><td id="ip_proto_tcp">ip_proto_tcp</td><td></td><td>6
</td></tr><tr><td id="ip_proto_udp">ip_proto_udp</td><td></td><td>17
</td></tr><tr><td id="ip_src">ip_src</td><td>offset of "source address" field in an IP packet header </td><td>12 </td></tr><tr><td id="ip_tos">ip_tos</td><td>offset of "type of service" field in an IP packet header </td><td>1 </td></tr><tr><td id="ip_ttl">ip_ttl</td><td>offset of "time to live" field in an IP packet header </td><td>8 </td></tr><tr><td id="ip_ver_ihl">ip_ver_ihl</td><td>offset of 4 bit "version" field and 4 bit "header length" field in an IP packet header </td><td>0 </td></tr></table><h2>implementation</h2><pre id="code">.include "../inc/common.i"
.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_cksum_ptr
.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
.ifdef TCP
.import tcp_init
.import tcp_process
.endif
.importzp copy_src
.segment "IP65ZP" : zeropage
; checksum
ip_cksum_ptr: .res 2 ; pointer to data to be checksummed
.bss
ip_cksum_len: .res 2 ; length of data to be checksummed
; 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
; temp storage for size calculation
len: .res 2
; flag for incoming broadcast packets
ip_broadcast: .res 1 ;flag set when an incoming IP packet was sent to a broadcast address
; 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
; ip protocols
ip_proto_icmp = 1
ip_proto_tcp = 6
ip_proto_udp = 17
; temp for calculating checksum
cksum: .res 3
; bad packet counters
bad_header: .res 2
bad_addr: .res 2
.code
; 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
jsr icmp_init
.ifdef TCP
jsr tcp_init
.endif
jsr udp_init
rts
;process an incoming packet & call the appropriate protocol handler
;inputs:
; eth_inp: should point to the received ethernet packet
;outputs:
; 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
@badpacket:
sec
rts
@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
:
unknown_protocol:
sec ; unknown protocol
rts
; 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 #$40
bne @badpacket
: lda ip_inp + ip_frag + 1
bne @badpacket
ldax #ip_inp ; verify checksum
stax ip_cksum_ptr
ldax #20
jsr ip_calc_cksum
cmp #0
bne @badpacket
cpx #0
bne @badpacket
clc
rts
@badpacket:
inc bad_header
bne :+
inc bad_header + 1
: sec
rts
; check that this packet was addressed to us
checkaddr:
lda #0
sta ip_broadcast
lda ip_inp + ip_dest ; compare ip address
cmp cfg_ip
bne @broadcast
lda ip_inp + ip_dest + 1
cmp cfg_ip + 1
bne @broadcast
lda ip_inp + ip_dest + 2
cmp cfg_ip + 2
bne @broadcast
lda ip_inp + ip_dest + 3
cmp cfg_ip + 3
bne @broadcast
@ok: clc
rts
@broadcast:
;jonno 2011-01-2
;previously this was just checking for 255.255.255.255
;however it is also possible to do a broadcast to a specific subnet, e.g. 10.5.1.255
;this is particularly common with NETBIOS over TCP
;we really should use the netmask, but as a kludge, just see if last octet is 255.
;this will work on a /24 network
;
inc ip_broadcast
; lda ip_inp + ip_dest ; check for broadcast
; and ip_inp + ip_dest + 1
; and ip_inp + ip_dest + 2
; and ip_inp + ip_dest + 3
lda ip_inp + ip_dest +3 ; check for broadcast
cmp #$ff
beq @ok
inc bad_addr
bne :+
inc bad_addr + 1
: sec
rts
; create an IP header (with all the appropriate flags and common fields set) inside an
; ethernet frame
;inputs:
; 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
; checksum fields set.
ip_create_packet:
lda #$45 ; set IP version and header length
sta ip_outp + ip_ver_ihl
lda #0 ; set type of service
sta ip_outp + ip_tos
; skip length
; skip ID
lda #$40 ; don't fragment - or should we not care?
sta ip_outp + ip_frag
lda #0
sta ip_outp + ip_frag + 1
lda #$40 ; set time to live
sta ip_outp + ip_ttl
; skip protocol
lda #0 ; clear checksum
sta ip_outp + ip_header_cksum
sta ip_outp + ip_header_cksum + 1
ldx #3 ; copy source address
: lda cfg_ip,x
sta ip_outp + ip_src,x
dex
bpl :-
; skip destination address
rts
; send an IP packet
;inputs
; eth_outp: should point to an ethernet frame that has an IP header created (by
; 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
; 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 copy_src ; borrow copymem zp...
lda ip_outp + ip_len
adc #>ip_outp
sta copy_src + 1
ldy #0
tya
sta (copy_src),y
sec ; round up to even number
@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
;jsr dbg_dump_ip_header
jmp eth_tx ; send packet and return status
; 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
; http://adtpro.cvs.sourceforge.net/viewvc/adtpro/adtpro/client/src/ip65/ip.s
;inputs:
; ip_cksum_ptr: points at buffer to be checksummed
; AX: length of buffer to be checksumed
;outputs:
; 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
lda ip_cksum_len+1
beq chksumlast
; If checksum is > 256, do the first runs.
ldy #0
clc
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
chksum_endloop_256:
lda cksum
adc #0
sta cksum
lda cksum+1
adc #0
sta cksum+1
bcs chksum_endloop_256
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
noinc1:
dec ip_cksum_len
chksum_noodd:
clc
php
ldy ip_cksum_len
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
chksum_loop1_end:
plp
chksum_endloop:
lda cksum
adc #0
sta cksum
lda cksum+1
adc #0
sta cksum+1
bcs chksum_endloop
lda cksum+1
eor #$ff
tax
lda cksum
eor #$ff
rts
;-- LICENSE FOR ip.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 Per Olofsson,
; MagerValp@gmail.com.
; Portions created by the Initial Developer are Copyright (C) 2009
; Per Olofsson. All Rights Reserved.
; -- LICENSE END --
</pre></body></html>