/*
 * fc_ipclassifier.cc -- click-fastclassifier functions for IPFilter and
 * IPClassifier
 * Eddie Kohler
 *
 * Copyright (c) 1999-2000 Massachusetts Institute of Technology
 * Copyright (c) 2000 Mazu Networks, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, subject to the conditions
 * listed in the Click LICENSE file. These conditions include: you must
 * preserve this copyright notice, and you cannot mention the copyright
 * holders in advertising related to the Software without their permission.
 * The Software is provided WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED. This
 * notice is a summary of the Click LICENSE file; the license in that file is
 * legally binding. */

#include <click/config.h>

#include <click/straccum.hh>
#include "click-fastclassifier.hh"

// magic constants imported from Click itself
#define IPCLASSIFIER_TRANSP_FAKE_OFFSET 64

static void
write_checked_body(const Classifier_Program &c, StringAccum &source)
{
  source << "  const unsigned *ip_data = (const unsigned *)p->ip_header();\n\
  const unsigned *transp_data = (const unsigned *)p->transport_header();\n\
  int l = p->length() + " << IPCLASSIFIER_TRANSP_FAKE_OFFSET << " - p->transport_header_offset();\n";
  source << "  assert(l < " << c.safe_length << ");\n";

  for (int i = 0; i < c.program.size(); i++) {
    const Classifier_Insn &e = c.program[i];
    
    int want_l = e.offset + 4;
    if (!e.mask.c[3]) {
      want_l--;
      if (!e.mask.c[2]) {
	want_l--;
	if (!e.mask.c[1])
	  want_l--;
      }
    }
    
    bool switched = (e.yes == i + 1);
    int branch1 = (switched ? e.no : e.yes);
    int branch2 = (switched ? e.yes : e.no);
    
    source << " lstep_" << i << ":\n";
    
    int offset;
    String datavar;
    String length_check;
    if (e.offset >= IPCLASSIFIER_TRANSP_FAKE_OFFSET) {
      offset = (e.offset - IPCLASSIFIER_TRANSP_FAKE_OFFSET)/4;
      datavar = "transp_data";
      length_check = "l < " + String(want_l);
    } else {
      offset = e.offset/4;
      datavar = "ip_data";
      length_check = "false";
    }
    
    if (want_l >= c.safe_length) {
      branch2 = e.no;
      goto output_branch2;
    }

    if (switched)
      source << "  if (" << length_check << " || ("
	     << datavar << "[" << offset << "] & "
	     << e.mask.u << "U) != " << e.value.u << "U)";
    else
      source << "  if (!(" << length_check << ") && ("
	     << datavar << "[" << offset << "] & "
	     << e.mask.u << "U) == " << e.value.u << "U)";
    if (branch1 <= -c.noutputs)
      source << " {\n    p->kill();\n    return;\n  }\n";
    else if (branch1 <= 0)
      source << " {\n    output(" << -branch1 << ").push(p);\n    return;\n  }\n";
    else
      source << "\n    goto lstep_" << branch1 << ";\n";
    
   output_branch2:
    if (branch2 <= -c.noutputs)
      source << "  p->kill();\n  return;\n";
    else if (branch2 <= 0)
      source << "  output(" << -branch2 << ").push(p);\n  return;\n";
    else if (branch2 != i + 1)
      source << "  goto lstep_" << branch2 << ";\n";
  }
}

static void
write_unchecked_body(const Classifier_Program &c, StringAccum &source)
{
  source << "  const unsigned *ip_data = (const unsigned *)p->ip_header();\n\
  const unsigned *transp_data = (const unsigned *)p->transport_header();\n";

  for (int i = 0; i < c.program.size(); i++) {
    const Classifier_Insn &e = c.program[i];
    
    bool switched = (e.yes == i + 1);
    int branch1 = (switched ? e.no : e.yes);
    int branch2 = (switched ? e.yes : e.no);
    source << " step_" << i << ":\n";

    int offset;
    String datavar;
    if (e.offset >= IPCLASSIFIER_TRANSP_FAKE_OFFSET)
      offset = (e.offset - IPCLASSIFIER_TRANSP_FAKE_OFFSET)/4, datavar = "transp_data";
    else
      offset = e.offset/4, datavar = "ip_data";
    
    if (switched)
      source << "  if ((" << datavar << "[" << offset << "] & " << e.mask.u
	     << "U) != " << e.value.u << "U)";
    else
      source << "  if ((" << datavar << "[" << offset << "] & " << e.mask.u
	     << "U) == " << e.value.u << "U)";
    if (branch1 <= -c.noutputs)
      source << " {\n    p->kill();\n    return;\n  }\n";
    else if (branch1 <= 0)
      source << " {\n    output(" << -branch1 << ").push(p);\n    return;\n  }\n";
    else
      source << "\n    goto step_" << branch1 << ";\n";
    if (branch2 <= -c.noutputs)
      source << "  p->kill();\n  return;\n";
    else if (branch2 <= 0)
      source << "  output(" << -branch2 << ").push(p);\n  return;\n";
    else if (branch2 != i + 1)
      source << "  goto step_" << branch2 << ";\n";
  }
}

static void
write_push_body(const Classifier_Program &c, StringAccum &source)
{
  if (c.safe_length >= IPCLASSIFIER_TRANSP_FAKE_OFFSET)
    source << "\
  if (p->length() + " << IPCLASSIFIER_TRANSP_FAKE_OFFSET << " - p->transport_header_offset() < " << c.safe_length << ")\n\
    length_checked_push(p);\n\
  else\n\
    length_unchecked_push(p);\n";
  else
    source << "  length_unchecked_push(p);\n";
}

extern "C" void
add_fast_classifiers_2()
{
  add_classifier_type("IPClassifier", IPCLASSIFIER_TRANSP_FAKE_OFFSET,
		      0,
		      write_checked_body,
		      write_unchecked_body,
		      write_push_body);
  add_classifier_type("IPFilter", IPCLASSIFIER_TRANSP_FAKE_OFFSET,
		      0,
		      write_checked_body,
		      write_unchecked_body,
		      write_push_body);
}