AntiGuide: UdpSwitchPythonTestlight

import sys, socket, datetime
# Switch UDP sur port 7778 et reponse au meme port
# protoyupe packet mis bout a bout
# accepte les paquets vides
trace=0
if len(sys.argv)>1 :
  if sys.argv[1]=="-t" : trace=1

if len(sys.argv) !=2+trace:
   print "appel sudo python "+sys.argv[0]+" [-t]  port "
   sys.exit()
port=int(sys.argv[1+trace])
trace=1
noadd=("","")
pilead=noadd
facead=noadd
nompile=""
nomface=""
aller="."
retour="."
pile=["",""]
token=["",""]


sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.bind(('',port))

print " SwitchPackets UDP port ", port," (frapper ^C pour abandonner)\n"


while 1:
 while 1:
  (buf, address)=sock.recvfrom(2048)
  if trace: print "- - - - "
  done=0
  if not len(buf):
   pass
  # isoler destinataire
  if trace: print "paquet recu:" , address,buf
  if (buf.find(":")<=0):
   print "pas exp/dest erreur venant de " , address
   break
  fromto=buf[:buf.find(":")]
 
  #si chgt RAZ
  if (fromto!=token[0]) and (fromto!=token[1]) :
 
     if (buf.find(">")<=0):
         print "pas >dest erreur venant de " , address
         break
     if trace: print "accepte fromto=", fromto
     token[0]=fromto
     token[1]=fromto[fromto.find(">")+1:]+">"+fromto[:fromto.find(">")]
     if trace: print "NEW ", token 

  cmd="?" # pour releve sans envoi
  contenu=""
  # commande
  # ? = releve sans envoi
  # = = envoi
  if len(buf)>len(fromto)+1:
    cmd=buf[buf.find(":")+1]
    contenu=buf[buf.find(":")+1:]
  connus="?="
  if connus.find(cmd)<0 :
    print "command unknown " , cmd, " in " , buf
    break

  if cmd=="?":
    if trace: print "relever seulement"
  if cmd=="=":
    if trace: print "ajouter et relever "
  
  # 
  contenu=buf[len(fromto):]
  debut=""
  vavient=0
  if fromto==token[1]: vavient=1
  if trace : print "paquet provenant de " , vavient

  if cmd=="=": 
     pile[vavient]=pile[vavient]+buf
     

  # reponse 
  if trace: print "chercher ",token[1-vavient]," dans ",pile[1-vavient] 
  ideb=pile[1-vavient].find(token[1-vavient],1)
  ideb0=pile[1-vavient].find(token[1-vavient],0)
  if trace: print "dans ",vavient," ideb=",ideb," ideb0=",ideb0
  debut=""
  if ideb>1:
         if trace: print "multiple"
         debut="="+pile[1-vavient][:ideb]
         pile[1-vavient]=pile[1-vavient][ideb:]
  if (ideb==-1) and (ideb0==0):
         debut="="+pile[1-vavient]
         pile[1-vavient]=""
 
  sock.sendto(debut, address)
  if trace: print "repondu de ",1-vavient," : <<<<" +debut+">>>>"
  done=1
    
  if trace: print "buffer reste :" ,vavient,pile[vavient]
  if trace: print "buffer reste :" ,1-vavient, pile[1-vavient]

  if (done == 0):
    print "errrur ",buf,address
    sock.sendto("error: "+buf, address)
  
 if trace: print "niveau 1"