Theory PolicyCombinators

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subsection ‹Policy Combinators›
theory 
  PolicyCombinators
  imports 
    PolicyCore
begin

text‹In order to ease the specification of a concrete policy, we
  define some combinators. Using these combinators, the specification
  of a policy gets very easy, and can be done similarly as in tools
  like IPTables.›

definition 
  allow_all_from :: "::adr net  ((,) packet  unit)" where
  "allow_all_from src_net =   {pa. src pa  src_net}  AU " 

definition 
  deny_all_from    :: "::adr net  ((,) packet  unit)" where
  "deny_all_from src_net   =  {pa. src pa   src_net}  DU "
        
definition
  allow_all_to    :: "::adr net  ((,) packet  unit)" where
  "allow_all_to dest_net   = {pa. dest pa   dest_net}   AU"

definition 
  deny_all_to :: "::adr net  ((,) packet  unit)" where
  "deny_all_to dest_net = {pa. dest pa  dest_net} DU "

definition 
  allow_all_from_to    :: "::adr net  ::adr net  ((,) packet  unit)" where
  "allow_all_from_to src_net dest_net = 
                                   {pa. src pa  src_net  dest pa  dest_net}  AU "

definition 
  deny_all_from_to    :: "::adr net  ::adr net  ((,) packet  unit)" where
  "deny_all_from_to src_net dest_net = {pa. src pa  src_net  dest pa  dest_net}  DU"


text‹All these combinators and the default rules are put into one
  single lemma called PolicyCombinators› to facilitate proving
  over policies.›


lemmas PolicyCombinators = allow_all_from_def deny_all_from_def
  allow_all_to_def deny_all_to_def allow_all_from_to_def
  deny_all_from_to_def UPFDefs
                           
end