#include <stdio.h>
#define _XOPEN_SOURCE
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include "cgilib.h"

/* This is ``salts'', the shared secret, it would need changing on a per-
   installation basis */
char salts[]="abcdefghijklmnopqrstuvwxyz";

/* Structure for memoizing transformations of outgoing CGI variables,
   when we need to print a variable, we must make sure to print
   memogrify(<internal name>) */
struct memo {
  char *str, *token;
  struct memo *next;
} *memobase = NULL;

/* This is the "heavy lifter" tranformation code */
char *transmogrify (char *str, int rv)
{
  if (rv<0)
    rv=rand()%(sizeof(salts)-2);

  return crypt(str, salts+rv);
}

/* Memogrify finds a previously-transformed name, if available, otherwise
   generates a new transformation and caches it. */
char *memogrify (char *str)
{
  struct memo *tmp;

  for (tmp=memobase;tmp;tmp=tmp->next) {
    if (strcmp(str, tmp->str) == 0) {
      return tmp->token;
    }
  }

  tmp=malloc(sizeof(struct memo));

  tmp->str=strdup(str);
  tmp->token=strdup(transmogrify(str, -1));
  tmp->next=memobase;

  memobase=tmp;

  return memobase->token;
}

/* This interfaces with and has the same signature as find_param from
   cgilib. It will try all possibly-generated transformations of a
   parameter name and return whatever it finds */
struct fieldval *find_param_crypto (char *name)
{
  int c;
  struct fieldval *rv;

  for (c=0;c<sizeof(salts)-2;c++)
    if ((rv=find_param(transmogrify(name, c))))
      return rv;

  return NULL;
}