scyther/src/compiler.c

#include <stdlib.h>
#include <stdio.h>
#include "tac.h"
#include "terms.h"
#include "termlists.h"
#include "runs.h"
#include "knowledge.h"
#include "symbols.h"
#include "substitutions.h"
#include "compiler.h"

/*
   Simple sys pointer as a global. Yields cleaner code although it's against programming standards.
   It is declared as static to hide it from the outside world, and to indicate its status.
   Other modules will just see a nicely implemented sys parameter of compile, so we can always change
   it later if somebody complains. Which they won't.
*/

static System sys;

/*
   Forward declarations.
*/

void tacProcess (Tac tc);
void levelInit (void);
void levelDone (void);
Term symbolDeclare (Symbol s, int isVar);
void levelTacDeclaration (Tac tc, int isVar);
Term levelFind (Symbol s, int i);
Term symbolFind (Symbol s);
Term tacTerm (Tac tc);
Termlist tacTermlist (Tac tc);

#define	levelDeclareVar(s)	levelTacDeclaration(s,1)
#define	levelDeclareConst(s)	levelTacDeclaration(s,0)
#define	levelVar(s)	symbolDeclare(s,1)
#define	levelConst(s)	symbolDeclare(s,0)

/* externally used:
 * TERM_Function in termlists.c for inversekeys
 * TERM_Type in runs.c for type determination.
 */

Term TERM_Agent;
Term TERM_Function;
Term TERM_Hidden;
Term TERM_Type;
Term TERM_Nonce;
Term TERM_Agent;

Term TERM_Claim;
Term CLAIM_Secret;
Term CLAIM_Nisynch;

/*
 * Global stuff
 */

#define MAXLEVELS 3
static Termlist leveltl[MAXLEVELS];
static int level;
static int maxruns;
static Protocol thisProtocol;
static Role thisRole;

/* ------------------------------------------------------------------- */

/*
   Compile the tac into the system
*/

void
compile (System mysys, Tac tc, int maxrunsset)
{
  int i;

  /* Init globals */
  maxruns = maxrunsset;
  /* transfer to global static variable */
  sys = mysys;
  /* init levels */
  for (i = 0; i < MAXLEVELS; i++)
    leveltl[i] = NULL;
  level = -1;
  levelInit ();

  /* Init system constants */
#define langhide(x,y) x = levelConst(symbolSysConst(" _" y "_ "))
#define langtype(x,y) x->stype = termlistAdd(x->stype,y);
#define langcons(x,y,z) x = levelConst(symbolSysConst(y)); langtype(x,z)

  langhide (TERM_Type, "Type");
  langhide (TERM_Hidden, "Hidden");
  langhide (TERM_Claim, "Claim");

  langcons (TERM_Agent, "Agent", TERM_Type);
  langcons (TERM_Function, "Function", TERM_Type);
  langcons (TERM_Nonce, "Nonce", TERM_Type);

  langcons (CLAIM_Secret, "Secret", TERM_Claim);
  langcons (CLAIM_Nisynch, "Nisynch", TERM_Claim);

  /* process the tac */
  tacProcess (tc);

  /* cleanup */
  levelDone ();
}

void
errorTac (int lineno)
{
  printf (" on line %i.\n", lineno);
  exit (1);
}

void
levelInit (void)
{
  level++;
  if (level >= MAXLEVELS)
    {
      printf ("ERROR: level is increased too much\n");
      exit (1);
    }
  leveltl[level] = NULL;
}

void
levelDone (void)
{
  if (level < 0)
    {
      printf ("ERROR: level is increased too much\n");
      exit (1);
    }
  leveltl[level] = NULL;
  level--;
}

Term
levelDeclare (Symbol s, int isVar, int level)
{
  Term t;

  t = levelFind (s, level);
  if (t == NULL)
    {
      /* new! */
      if (isVar)
	{
	  t = makeTermType (VARIABLE, s, -(level + 1));
	  sys->variables = termlistAdd (sys->variables, t);
	}
      else
	{
	  t = makeTermType (GLOBAL, s, -(level + 1));
	}
      leveltl[level] = termlistAdd (leveltl[level], t);

      /* add to relevant list */
      switch (level)
	{
	case 0:
	  sys->locals = termlistAdd (sys->locals, t);
	  break;
	case 1:
	  thisProtocol->locals = termlistAdd (thisProtocol->locals, t);
	  break;
	case 2:
	  thisRole->locals = termlistAdd (thisRole->locals, t);
	  break;
	}
    }
  return t;
}

Term
symbolDeclare (Symbol s, int isVar)
{
  return levelDeclare (s, isVar, level);
}

Term
levelFind (Symbol s, int level)
{
  Termlist tl;

  tl = leveltl[level];
  while (tl != NULL)
    {
      if (isTermLeaf (tl->term))
	{
	  if (tl->term->symb == s)
	    {
	      return tl->term;
	    }
	}
      tl = tl->next;
    }
  return NULL;
}

Term
symbolFind (Symbol s)
{
  int i;
  Term t;

  i = level;
  while (i >= 0)
    {
      t = levelFind (s, i);
      if (t != NULL)
	return t;
      i--;
    }
  return NULL;
}

void
defineUsertype (Tac tcdu)
{
  Tac tc;
  Term t;
  Term tfind;

  tc = tcdu->t1.tac;

  if (tc == NULL)
    {
      printf ("ERROR: empty usertype declaration.\n");
      errorTac (tcdu->lineno);
    }
  while (tc != NULL && tc->op == TAC_STRING)
    {
      /* check whether this term is already declared in the same way
       * (i.e. as a type) */

      tfind = levelFind (tc->t1.sym, 0);
      if (tfind == NULL)
	{
	  /* this is what we expected: this type is not declared yet */
	  t = levelDeclare (tc->t1.sym, 0, 0);
	  t->stype = termlistAdd (NULL, TERM_Type);
	}
      else
	{
	  /* oi!, there's already one. Let's hope is is a type too. */
	  if (inTermlist (tfind->stype, TERM_Type))
	    {
	      /* phew. warn anyway */
	      printf ("WARNING: double declaration of usertype ");
	      termPrint (tfind);
	      printf ("\n");
	    }
	  else
	    {
	      /* that's not right! */
	      printf ("ERROR: conflicting definitions for ");
	      termPrint (tfind);
	      printf (" in usertype definition ");
	      errorTac (tc->lineno);
	    }
	}
      tc = tc->next;
    }
}

void
levelTacDeclaration (Tac tc, int isVar)
{
  Tac tscan;
  Termlist typetl = NULL;
  Term t;

  tscan = tc->t2.tac;
  if (!isVar && tscan->next != NULL)
    {
      printf ("ERROR: Multiple types not allowed for constants ");
      errorTac (tscan->lineno);
    }
  while (tscan != NULL && tscan->op == TAC_STRING)
    {
      /* apparently there is type info, termlist? */
      t = levelFind (tscan->t1.sym, 0);

      if (t == NULL)
	{
	  /* not declared, that is unacceptable. */
	  printf ("ERROR: type ");
	  symbolPrint (tscan->t1.sym);
	  printf (" was not declared ");
	  errorTac (tscan->lineno);
	}
      else
	{
	  if (!inTermlist (t->stype, TERM_Type))
	    {
	      printf ("ERROR: non-type constant in type declaration ");
	      errorTac (tscan->lineno);
	    }
	}
      typetl = termlistAdd (typetl, t);
      tscan = tscan->next;
    }
  /* parse all constants and vars */
  tscan = tc->t1.tac;
  while (tscan != NULL)
    {
      t = symbolDeclare (tscan->t1.sym, isVar);
      t->stype = typetl;
      tscan = tscan->next;
    }
}

void
commEvent (int event, Tac tc)
{
  /* Add an event to the roledef, send or read */
  Term fromrole = NULL;
  Term torole = NULL;
  Term msg = NULL;
  Term label = NULL;
  Term claim = NULL;
  Term claimbig = NULL;
  int n = 0;
  Tac trip;

  /* Construct label, if any */
  if (tc->t1.sym == NULL)
    {
      label = NULL;
    }
  else
    {
      label = levelFind (tc->t1.sym, level - 1);
      if (label == NULL)
	{
	  /* effectively, labels are bound to the protocol */
	  level--;
	  label = levelConst (tc->t1.sym);
	  level++;
	}
    }
  trip = tc->t2.tac;
  switch (event)
    {
    case READ:
    case SEND:
      /* now parse triplet info */
      if (trip == NULL || trip->next == NULL || trip->next->next == NULL)
	{
	  printf ("ERROR in %i event ", event);
	  errorTac (tc->lineno);
	}
      fromrole = tacTerm (trip);
      torole = tacTerm (trip->next);
      msg = tacTerm (tacTuple ((trip->next->next)));

      break;
    case CLAIM:
      /* now parse tuple info */
      if (trip == NULL || trip->next == NULL)
	{
	  printf ("ERROR in %i event ", event);
	  errorTac (tc->lineno);
	}
      fromrole = tacTerm (trip);
      claimbig = tacTerm (tacTuple ((trip->next)));
      /* check for several types */
      claim = tupleProject (claimbig, 0);
      torole = claim;
      /* check for obvious flaws */
      if (claim == NULL)
	{
	  printf ("ERROR: invalid claim specification ");
	  errorTac (trip->next->lineno);
	}
      if (!inTermlist (claim->stype, TERM_Claim))
	{
	  printf ("ERROR: unknown claim type ");
	  termPrint (claim);
	  errorTac (trip->next->lineno);
	}
      /* unfold parameters to msg */
      msg = NULL;
      n = tupleCount (claimbig) - 1;
      if (n < 1)
	{
	  /* no parameters */
	  n = 0;
	}
      else
	{
	  /* n parameters */
	  msg = deVar (claimbig)->op2;
	  if (tupleCount (msg) != n)
	    {
	      printf
		("ERROR: something went wrong in the claim tuple parameter unfolding ");
	      errorTac (trip->next->lineno);
	    }
	}

      /* handles all claim types differently */

      if (claim == CLAIM_Secret)
	{
	  if (n == 0)
	    {
	      printf
		("ERROR: secrecy claim requires a list of terms to be secret ");
	      errorTac (trip->next->lineno);
	    }
	  break;
	}
      if (claim == CLAIM_Nisynch)
	{
	  if (n != 0)
	    {
	      printf ("ERROR: nisynch claim has no parameters ");
	      errorTac (trip->next->lineno);
	    }
	  break;
	}

      /* hmm, no handler yet */

      printf ("ERROR: No know handler for this claim type: ");
      termPrint (claim);
      printf (" ");
      errorTac (trip->next->lineno);
      break;
    }
  /* and make that event */
  thisRole->roledef = roledefAdd (thisRole->roledef, event, label,
				  fromrole, torole, msg);
}

int
normalDeclaration (Tac tc)
{
  switch (tc->op)
    {
    case TAC_VAR:
      levelDeclareVar (tc);
      if (level < 2 && tc->t3.tac == NULL)
	knowledgeAddTermlist (sys->know, tacTermlist (tc->t1.tac));
      break;
    case TAC_CONST:
      levelDeclareConst (tc);
      if (level < 2 && tc->t3.tac == NULL)
	knowledgeAddTermlist (sys->know, tacTermlist (tc->t1.tac));
      break;
    case TAC_SECRET:
      levelDeclareConst (tc);
      break;
    case TAC_COMPROMISED:
      knowledgeAddTermlist (sys->know, tacTermlist (tc->t1.tac));
      break;
    case TAC_INVERSEKEYS:
      knowledgeAddInverse (sys->know, tacTerm (tc->t1.tac), tacTerm (tc->t2.tac));
      break;
    default:
      /* abort with false */
      return 0;
    }
  return 1;
}

void
roleCompile (Term nameterm, Tac tc)
{
  Role r;

  /* make new (empty) current protocol with name */
  r = roleCreate (nameterm);
  thisRole = r;
  /* add protocol to list */
  r->next = thisProtocol->roles;
  thisProtocol->roles = r;

  /* parse the content of the role */
  levelInit ();

  while (tc != NULL)
    {
      switch (tc->op)
	{
	case TAC_READ:
	  commEvent (READ, tc);
	  break;
	case TAC_SEND:
	  commEvent (SEND, tc);
	  break;
	case TAC_CLAIM:
	  commEvent (CLAIM, tc);
	  break;
	default:
	  if (!normalDeclaration (tc))
	    {
	      printf ("ERROR: illegal command %i in role ", tc->op);
	      termPrint (thisRole->nameterm);
	      printf (" ");
	      errorTac (tc->lineno);
	    }
	  break;
	}
      tc = tc->next;
    }
  levelDone ();
}

void
runInstanceCreate (Tac tc)
{
  /* create an instance of an existing role
   * tac1 is the dot-separated reference to the role.
   * tac2 is the list of parameters to be filled in.
   */

  Protocol p;
  Role r;
  Symbol psym, rsym;
  Termlist instParams;

  /* check whether we can still do it */
  if (sys->maxruns >= maxruns)
    return;

  /* first, locate the protocol */
  psym = tc->t1.tac->t1.sym;
  p = sys->protocols;
  while (p != NULL && p->nameterm->symb != psym)
    p = p->next;
  if (p == NULL)
    {
      printf ("Trying to create a run of a non-declared protocol ");
      symbolPrint (psym);
      printf (" ");
      errorTac (tc->lineno);
    }

  /* locate the role */
  rsym = tc->t1.tac->t2.sym;
  r = p->roles;
  while (r != NULL && r->nameterm->symb != rsym)
    r = r->next;
  if (r == NULL)
    {
      printf ("Protocol ");
      symbolPrint (psym);
      printf (" has no role called ");
      symbolPrint (rsym);
      printf (" ");
      errorTac (tc->lineno);
    }

  /* we now know what we are instancing, equal numbers? */
  instParams = tacTermlist (tc->t2.tac);
  if (termlistLength (instParams) != termlistLength (p->rolenames))
    {
      printf
	("Run instance has different number of parameters than protocol ");
      termPrint (p->nameterm);
      printf (" ");
      errorTac (tc->lineno);
    }

  /* equal numbers, so it seems to be safe */
  roleInstance (sys, p, r, instParams);

  /* after creation analysis */
  /* AC1: untrusted agents */
  /*      first: determine whether the run is untrusted,
   *      by checking whether one of the untrusted agents occurs
   *      in the run instance  */
  if (untrustedAgent (sys, instParams))
    {
      /* nothing yet */
      /* claims handle this themselves */

      /* some reduction might be possible, by cutting of the last few actions
       * of such an untrusted run */

      /* but most of it might be handled dynamically */
    }

  /* AC2: originator assumption for CLP ? */
  /* TODO */
}

void
protocolCompile (Symbol prots, Tac tc, Tac tcroles)
{
  Protocol pr;
  Term t;

  if (levelFind (prots, level) != NULL)
    {
      printf ("ERROR: Double declaration of protocol ");
      symbolPrint (prots);
      printf (" ");
      errorTac (tc->lineno);
    }
  /* make new (empty) current protocol with name */
  pr = protocolCreate (levelConst (prots));
  thisProtocol = pr;
  /* add protocol to list */
  pr->next = sys->protocols;
  sys->protocols = pr;

  levelInit ();
  /* add the role names */
  pr->rolenames = NULL;
  while (tcroles != NULL)
    {
      pr->rolenames =
	termlistAppend (pr->rolenames, levelConst (tcroles->t1.sym));
      tcroles = tcroles->next;
    }

  /* parse the content of the protocol */
  while (tc != NULL)
    {
      switch (tc->op)
	{
	case TAC_UNTRUSTED:
	  sys->untrusted =
	    termlistConcat (sys->untrusted, tacTermlist (tc->t1.tac));
	  break;
	case TAC_ROLE:
	  t = levelFind (tc->t1.sym, level);
	  if (t != NULL)
	    {
	      roleCompile (t, tc->t2.tac);
	    }
	  else
	    {
	      printf ("ERROR: undeclared role ");
	      symbolPrint (tc->t1.sym);
	      printf (" in protocol ");
	      termPrint (pr->nameterm);
	      errorTac (tc->t1.sym->lineno);
	    }
	  break;
	default:
	  if (!normalDeclaration (tc))
	    {
	      printf ("ERROR: illegal command %i in protocol ", tc->op);
	      termPrint (thisProtocol->nameterm);
	      errorTac (tc->lineno);
	    }
	  break;
	}
      tc = tc->next;
    }
  levelDone ();
}

void
tacProcess (Tac tc)
{
  while (tc != NULL)
    {
      switch (tc->op)
	{
	case TAC_PROTOCOL:
	  protocolCompile (tc->t1.sym, tc->t2.tac, tc->t3.tac);
	  break;
	case TAC_UNTRUSTED:
	  sys->untrusted =
	    termlistConcat (sys->untrusted, tacTermlist (tc->t1.tac));
	  break;
	case TAC_RUN:
	  runInstanceCreate (tc);
	  break;
	case TAC_USERTYPE:
	  defineUsertype (tc);
	  break;
	default:
	  if (!normalDeclaration (tc))
	    {
	      printf ("ERROR: illegal command %i at the global level.\n",
		      tc->op);
	      errorTac (tc->lineno);
	    }
	  break;
	}
      tc = tc->next;
    }
}

Term
tacTerm (Tac tc)
{
  switch (tc->op)
    {
    case TAC_ENCRYPT:
      return makeTermEncrypt (tacTerm (tc->t1.tac), tacTerm (tc->t2.tac));
    case TAC_TUPLE:
      return makeTermTuple (tacTerm (tc->t1.tac), tacTerm (tc->t2.tac));
    case TAC_STRING:
      {
	Term t = symbolFind (tc->t1.sym);
	if (t == NULL)
	  {
	    printf ("Undeclared symbol ");
	    symbolPrint (tc->t1.sym);
	    errorTac (tc->lineno);
	  }
	return t;
      }
    default:
      return NULL;
    }
}

Termlist
tacTermlist (Tac tc)
{
  Termlist tl = NULL;

  while (tc != NULL)
    {
      tl = termlistAppend (tl, tacTerm (tc));
      tc = tc->next;
    }
  return tl;
}