obp/obp/pkg/netinet/icmp.fth

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\ Hypervisor Software File: icmp.fth
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id: @(#)icmp.fth 1.1 04/09/07
purpose: ICMP support
copyright: Copyright 2004 Sun Microsystems, Inc.  All Rights Reserved
copyright: Use is subject to license terms.

\ RFC 792: Internet Control Message Protocol

headerless

struct
   /ip-header  field  >icmp-iphdr       \ IP header, no options
   /c          field  >icmp-type        \ Message type
   /c          field  >icmp-code        \ Message type subcode
   /w          field  >icmp-cksum       \ Checksum
   0           field  >icmp-gwaddr      \ Preferred gateway (ICMP_REDIRECT)
   /w          field  >icmp-id          \ Message id (ICMP_ECHO)
   /w          field  >icmp-seq         \ Sequence number (ICMP_ECHO)
   0           field  >icmp-ip          \ IP header (ICMP_REDIRECT)
   0           field  >icmp-data        \ Data (ICMP_ECHO)
constant /icmpip-header

\ ICMP message types
0     constant  ICMP_ECHOREPLY          \ Echo reply
d# 5  constant  ICMP_REDIRECT           \ Better route available
d# 8  constant  ICMP_ECHO               \ Echo request

\ Compute checksum on the ICMP (IP payload) packet
: icmp-checksum ( ip-pkt -- checksum )
    0 swap ippkt>payload in-cksum
;

\ Fill in ICMP checksum and send the packet
: icmp-output ( ip-pkt -- )
   0                  over >icmp-cksum  htonw!          ( pkt )
   dup icmp-checksum  over >icmp-cksum  htonw!          ( pkt )
   ip-output  drop                                      ( )
;

\ Handle an incoming ICMP redirect. Network redirects and host redirects
\ are treated identically.
: icmp-redirect ( ip-pkt -- )
   dup >icmp-ip >ip-dest  swap >icmp-gwaddr  RT_HOST route-update
;

\ Respond to ICMP ECHO requests.
: icmp-reflect ( ip-pkt -- )
   dup >ip-src     over >ip-dest    copy-ip-addr        ( pkt )
   my-ip-addr      over >ip-src     copy-ip-addr        ( pkt )
   ICMP_ECHOREPLY  over >icmp-type  c!                  ( pkt )
   icmp-output                                          ( )
;

\ Process incoming ICMP packet
: icmp-input ( pkt -- )
   my-ip-addr inaddr-any? 0=  if                                ( pkt )
      dup icmp-checksum  0=  if                                 ( pkt )
         dup >icmp-type c@  case
            ICMP_ECHO      of  icmp-reflect exit  endof
            ICMP_REDIRECT  of  dup icmp-redirect  endof
         endcase
      then                                                      ( pkt )
   then                                                         ( pkt )
   pkt-free                                                     ( )
;
['] icmp-input  to (icmp-input)

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