/*
 * SmartRoute phase 1
 * connection rule patch
 * by Tony Vencill (Tonto on IRC) <vencill@bga.com>
 *
 * The majority of this file is a recusive descent parser used to convert
 * connection rules into expression trees when the conf file is read.
 * All parsing structures and types are hidden in the interest of good
 * programming style and to make possible future data structure changes
 * without affecting the interface between this patch and the rest of the
 * server.  The only functions accessible externally are crule_parse,
 * crule_free, and crule_eval.  Prototypes for these functions can be
 * found in h.h.
 *
 * Please direct any connection rule or SmartRoute questions to Tonto on
 * IRC or by email to vencill@bga.com.
 *
 * For parser testing, defining CR_DEBUG generates a stand-alone parser
 * that takes rules from stdin and prints out memory allocation
 * information and the parsed rule.  This stand alone parser is ignorant
 * of the irc server and thus cannot do rule evaluation.  Do not define
 * this flag when compiling the server!  If you wish to generate the
 * test parser, compile from the ircd directory with a line similar to
 * cc -o parser -DCR_DEBUG crule.c
 *
 * The define CR_CHKCONF is provided to generate routines needed in
 * chkconf.  These consist of the parser, a different crule_parse that
 * prints errors to stderr, and crule_free (just for good style and to
 * more closely simulate the actual ircd environment).  crule_eval and
 * the rule functions are made empty functions as in the stand-alone
 * test parser.
 */

#ifndef CR_DEBUG
/* ircd functions and types we need */
#include "struct.h"
#include "common.h"
#include "sys.h"
#include "h.h"
#include <string.h>

char *collapse(char *pattern);
extern Client *client;

ID_Copyright("(C) Tony Vincell");

#else
/* includes and defines to make the stand-alone test parser */
#include <stdio.h>
#include <string.h>
#define BadPtr(x) (!(x) || (*(x) == '\0'))
#endif

#if defined(CR_DEBUG) || defined(CR_CHKCONF)
#undef safe_free
#undef free
#define safe_free free
#endif

/* some constants and shared data types */
#define CR_MAXARGLEN 80		/* why 80? why not? it's > hostname lengths */
#define CR_MAXARGS 3		/* there's a better way to do this, but not now */

/* some symbols for easy reading */
enum crule_token
    { CR_UNKNOWN, CR_END, CR_AND, CR_OR, CR_NOT, CR_OPENPAREN, CR_CLOSEPAREN,
	CR_COMMA, CR_WORD
};
enum crule_errcode
    { CR_NOERR, CR_UNEXPCTTOK, CR_UNKNWTOK, CR_EXPCTAND, CR_EXPCTOR,
	CR_EXPCTPRIM, CR_EXPCTOPEN, CR_EXPCTCLOSE, CR_UNKNWFUNC, CR_ARGMISMAT
};

/* expression tree structure, function pointer, and tree pointer */
/* local! */
typedef int (*crule_funcptr) (int, void **);
struct crule_treestruct {
	crule_funcptr funcptr;
	int  numargs;
	void *arg[CR_MAXARGS];	/* for operators arg points to a tree element;
				   for functions arg points to a char string */
};
typedef struct crule_treestruct crule_treeelem;
typedef crule_treeelem *crule_treeptr;

/* rule function prototypes - local! */
int crule_connected(int, void **);
int crule_directcon(int, void **);
int crule_via(int, void **);
int crule_directop(int, void **);
int crule__andor(int, void **);
int crule__not(int, void **);

/* parsing function prototypes - local! */
int crule_gettoken(int *, char **);
void crule_getword(char *, int *, int, char **);
int crule_parseandexpr(crule_treeptr *, int *, char **);
int crule_parseorexpr(crule_treeptr *, int *, char **);
int crule_parseprimary(crule_treeptr *, int *, char **);
int crule_parsefunction(crule_treeptr *, int *, char **);
int crule_parsearglist(crule_treeptr, int *, char **);

#if defined(CR_DEBUG) || defined(CR_CHKCONF)
/* prototypes for the test parser; if not debugging, these are
 * defined in h.h */
char *crule_parse(char *);
void crule_free(char **);
#ifdef CR_DEBUG
void print_tree(crule_treeptr));
#endif
#endif

/* error messages */
char *crule_errstr[] = {
	"Unknown error",	/* NOERR? - for completeness */
	"Unexpected token",	/* UNEXPCTTOK */
	"Unknown token",	/* UNKNWTOK */
	"And expr expected",	/* EXPCTAND */
	"Or expr expected",	/* EXPCTOR */
	"Primary expected",	/* EXPCTPRIM */
	"( expected",		/* EXPCTOPEN */
	") expected",		/* EXPCTCLOSE */
	"Unknown function",	/* UNKNWFUNC */
	"Argument mismatch"	/* ARGMISMAT */
};

/* function table - null terminated */
struct crule_funclistent {
	char name[15];		/* MAXIMUM FUNCTION NAME LENGTH IS 14 CHARS!! */
	int  reqnumargs;
	crule_funcptr funcptr;
};
struct crule_funclistent crule_funclist[] = {
	/* maximum function name length is 14 chars */
	{"connected", 1, crule_connected},
	{"directcon", 1, crule_directcon},
	{"via", 2, crule_via},
	{"directop", 0, crule_directop},
	{"", 0, NULL}		/* this must be here to mark end of list */
};

int  crule_connected(int numargs, void *crulearg[])
{
#if !defined(CR_DEBUG) && !defined(CR_CHKCONF)
	Client *client;

	/* taken from cmd_links */
	/* Faster this way -- codemastr*/
	list_for_each_entry(client, &global_server_list, client_node)
	{
		if (!match_simple((char *)crulearg[0], client->name))
			continue;
		return (1);
	}
	return (0);
#endif
}

int  crule_directcon(int numargs, void *crulearg[])
{
#if !defined(CR_DEBUG) && !defined(CR_CHKCONF)
	Client *client;

	/* adapted from cmd_trace and exit_one_client */
	/* XXX: iterate server_list when added */
	list_for_each_entry(client, &lclient_list, lclient_node)
	{
		if (!IsServer(client))
			continue;
		if (!match_simple((char *)crulearg[0], client->name))
			continue;
		return (1);
	}
	return (0);
#endif
}

int  crule_via(int numargs, void *crulearg[])
{
#if !defined(CR_DEBUG) && !defined(CR_CHKCONF)
	Client *client;

	/* adapted from cmd_links */
	/* Faster this way -- codemastr */
	list_for_each_entry(client, &global_server_list, client_node)
	{
		if (!match_simple((char *)crulearg[1], client->name))
			continue;
		if (!match_simple((char *)crulearg[0], client->uplink->name))
			continue;
		return (1);
	}
	return (0);
#endif
}

int  crule_directop(int numargs, void *crulearg[])
{
#if !defined(CR_DEBUG) && !defined(CR_CHKCONF)
	Client *client;

	/* adapted from cmd_trace */
	list_for_each_entry(client, &lclient_list, lclient_node)
	{
		if (!IsOper(client))
			continue;

		return (1);
	}

	return (0);
#endif
}

int  crule__andor(int numargs, void *crulearg[])
{
	int  result1;

	result1 = ((crule_treeptr) crulearg[0])->funcptr
	    (((crule_treeptr) crulearg[0])->numargs,
	    (void *)((crule_treeptr) crulearg[0])->arg);
	if (crulearg[2])	/* or */
		return (result1 ||
		    ((crule_treeptr) crulearg[1])->funcptr
		    (((crule_treeptr) crulearg[1])->numargs,
		    (void *)((crule_treeptr) crulearg[1])->arg));
	else
		return (result1 &&
		    ((crule_treeptr) crulearg[1])->funcptr
		    (((crule_treeptr) crulearg[1])->numargs,
		    (void *)((crule_treeptr) crulearg[1])->arg));
}

int  crule__not(int numargs, void *crulearg[])
{
	return (!((crule_treeptr) crulearg[0])->funcptr
	    (((crule_treeptr) crulearg[0])->numargs,
	    (void *)((crule_treeptr) crulearg[0])->arg));
}

#if !defined(CR_DEBUG) && !defined(CR_CHKCONF)
int  crule_eval(rule)
	char *rule;
{
	return (((crule_treeptr) rule)->funcptr
	    (((crule_treeptr) rule)->numargs, ((crule_treeptr) rule)->arg));
}
#endif

int  crule_gettoken(int *next_tokp, char **ruleptr)
{
	char pending = '\0';

	*next_tokp = CR_UNKNOWN;
	while (*next_tokp == CR_UNKNOWN)
		switch (*(*ruleptr)++)
		{
		  case ' ':
		  case '\t':
			  break;
		  case '&':
			  if (pending == '\0')
				  pending = '&';
			  else if (pending == '&')
				  *next_tokp = CR_AND;
			  else
				  return (CR_UNKNWTOK);
			  break;
		  case '|':
			  if (pending == '\0')
				  pending = '|';
			  else if (pending == '|')
				  *next_tokp = CR_OR;
			  else
				  return (CR_UNKNWTOK);
			  break;
		  case '!':
			  *next_tokp = CR_NOT;
			  break;
		  case '(':
			  *next_tokp = CR_OPENPAREN;
			  break;
		  case ')':
			  *next_tokp = CR_CLOSEPAREN;
			  break;
		  case ',':
			  *next_tokp = CR_COMMA;
			  break;
		  case '\0':
			  (*ruleptr)--;
			  *next_tokp = CR_END;
			  break;
		  /* Both - and : can appear in hostnames so they must not be 
		   * treated as separators -- codemastr */
		  default:
			  if ((isalpha(*(--(*ruleptr)))) || (**ruleptr == '*')
			      || (**ruleptr == '?') || (**ruleptr == '.')
			      || (**ruleptr == '-') || (**ruleptr == ':'))
				  *next_tokp = CR_WORD;
			  else
				  return (CR_UNKNWTOK);
			  break;
		}
	return CR_NOERR;
}

void crule_getword(char *word, int *wordlenp, int maxlen, char **ruleptr)
{
	char *word_ptr, c;

	word_ptr = word;
	/* Both - and : can appear in hostnames so they must not be 
	 * treated as separators -- codemastr */

	while ((isalnum(**ruleptr)) || (**ruleptr == '*') ||
	    (**ruleptr == '?') || (**ruleptr == '.') || (**ruleptr == '-') ||
	    (**ruleptr == ':'))
	{
		c = *(*ruleptr)++;
		if (maxlen > 1) /* >1 instead of >0 so we (possibly) still have room for NUL */
		{
			*word_ptr++ = c;
			maxlen--;
		}
	}
	if (maxlen)
		*word_ptr = '\0';
	*wordlenp = word_ptr - word;
}

/*
 * Grammar
 *   rule:
 *     orexpr END          END is end of input
 *   orexpr:
 *     andexpr
 *     andexpr || orexpr
 *   andexpr:
 *     primary
 *     primary && andexpr
 *  primary:
 *    function
 *    ! primary
 *    ( orexpr )
 *  function:
 *    word ( )             word is alphanumeric string, first character
 *    word ( arglist )       must be a letter
 *  arglist:
 *    word
 *    word , arglist
 */

char *crule_parse(char *rule)
{
	char *ruleptr = rule;
	int  next_tok;
	crule_treeptr ruleroot = NULL;
	int  errcode = CR_NOERR;

	if ((errcode = crule_gettoken(&next_tok, &ruleptr)) == CR_NOERR) {
		if ((errcode = crule_parseorexpr(&ruleroot, &next_tok,
		    &ruleptr)) == CR_NOERR) {
			if (ruleroot != NULL) {
				if (next_tok == CR_END)
					return ((char *)ruleroot);
				else
					errcode = CR_UNEXPCTTOK;
			}
			else
				errcode = CR_EXPCTOR;
		}
	}
	if (ruleroot != NULL)
		crule_free((char **)&ruleroot);
	return NULL;
}

int  crule_parseorexpr(crule_treeptr *orrootp, int *next_tokp, char **ruleptr)
{
	int  errcode = CR_NOERR;
	crule_treeptr andexpr;
	crule_treeptr orptr;

	*orrootp = NULL;
	while (errcode == CR_NOERR)
	{
		errcode = crule_parseandexpr(&andexpr, next_tokp, ruleptr);
		if ((errcode == CR_NOERR) && (*next_tokp == CR_OR))
		{
			orptr =
			    (crule_treeptr) safe_alloc(sizeof(crule_treeelem));
#ifdef CR_DEBUG
			(void)fprintf(stderr, "allocating or element at %ld\n", orptr);
#endif
			orptr->funcptr = crule__andor;
			orptr->numargs = 3;
			orptr->arg[2] = (void *)1;
			if (*orrootp != NULL)
			{
				(*orrootp)->arg[1] = andexpr;
				orptr->arg[0] = *orrootp;
			}
			else
				orptr->arg[0] = andexpr;
			*orrootp = orptr;
		}
		else
		{
			if (*orrootp != NULL)
				if (andexpr != NULL)
				{
					(*orrootp)->arg[1] = andexpr;
					return (errcode);
				}
				else
				{
					(*orrootp)->arg[1] = NULL;	/* so free doesn't seg fault */
					return (CR_EXPCTAND);
				}
			else
			{
				*orrootp = andexpr;
				return (errcode);
			}
		}
		if ((errcode = crule_gettoken(next_tokp, ruleptr)) != CR_NOERR)
			return (errcode);
	}
	return (errcode);
}

int  crule_parseandexpr(crule_treeptr *androotp, int *next_tokp, char **ruleptr)
{
	int  errcode = CR_NOERR;
	crule_treeptr primary;
	crule_treeptr andptr;

	*androotp = NULL;
	while (errcode == CR_NOERR)
	{
		errcode = crule_parseprimary(&primary, next_tokp, ruleptr);
		if ((errcode == CR_NOERR) && (*next_tokp == CR_AND))
		{
			andptr =
			    (crule_treeptr) safe_alloc(sizeof(crule_treeelem));
#ifdef CR_DEBUG
			(void)fprintf(stderr, "allocating and element at %ld\n", andptr);
#endif
			andptr->funcptr = crule__andor;
			andptr->numargs = 3;
			andptr->arg[2] = (void *)0;
			if (*androotp != NULL)
			{
				(*androotp)->arg[1] = primary;
				andptr->arg[0] = *androotp;
			}
			else
				andptr->arg[0] = primary;
			*androotp = andptr;
		}
		else
		{
			if (*androotp != NULL)
				if (primary != NULL)
				{
					(*androotp)->arg[1] = primary;
					return (errcode);
				}
				else
				{
					(*androotp)->arg[1] = NULL;	/* so free doesn't seg fault */
					return (CR_EXPCTPRIM);
				}
			else
			{
				*androotp = primary;
				return (errcode);
			}
		}
		if ((errcode = crule_gettoken(next_tokp, ruleptr)) != CR_NOERR)
			return (errcode);
	}
	return (errcode);
}

int  crule_parseprimary(crule_treeptr *primrootp, int *next_tokp, char **ruleptr)
{
	crule_treeptr *insertionp;
	int  errcode = CR_NOERR;

	*primrootp = NULL;
	insertionp = primrootp;
	while (errcode == CR_NOERR)
	{
		switch (*next_tokp)
		{
		  case CR_OPENPAREN:
			  if ((errcode =
			      crule_gettoken(next_tokp, ruleptr)) != CR_NOERR)
				  break;
			  if ((errcode =
			      crule_parseorexpr(insertionp, next_tokp,
			      ruleptr)) != CR_NOERR)
				  break;
			  if (*insertionp == NULL)
			  {
				  errcode = CR_EXPCTAND;
				  break;
			  }
			  if (*next_tokp != CR_CLOSEPAREN)
			  {
				  errcode = CR_EXPCTCLOSE;
				  break;
			  }
			  errcode = crule_gettoken(next_tokp, ruleptr);
			  break;
		  case CR_NOT:
			  *insertionp =
			      (crule_treeptr) safe_alloc(sizeof(crule_treeelem));
#ifdef CR_DEBUG
			  (void)fprintf(stderr,
			      "allocating primary element at %ld\n",
			      *insertionp);
#endif
			  (*insertionp)->funcptr = crule__not;
			  (*insertionp)->numargs = 1;
			  (*insertionp)->arg[0] = NULL;
			  insertionp =
			      (crule_treeptr *) & ((*insertionp)->arg[0]);
			  if ((errcode =
			      crule_gettoken(next_tokp, ruleptr)) != CR_NOERR)
				  break;
			  continue;
		  case CR_WORD:
			  errcode =
			      crule_parsefunction(insertionp, next_tokp,
			      ruleptr);
			  break;
		  default:
			  if (*primrootp == NULL)
				  errcode = CR_NOERR;
			  else
				  errcode = CR_EXPCTPRIM;
			  break;
		}
		return (errcode);
	}
	return (errcode);
}

int  crule_parsefunction(crule_treeptr *funcrootp, int *next_tokp, char **ruleptr)
{
	int  errcode = CR_NOERR;
	char funcname[CR_MAXARGLEN];
	int  namelen;
	int  funcnum;

	*funcrootp = NULL;
	crule_getword(funcname, &namelen, CR_MAXARGLEN, ruleptr);
	if ((errcode = crule_gettoken(next_tokp, ruleptr)) != CR_NOERR)
		return (errcode);
	if (*next_tokp == CR_OPENPAREN)
	{
		for (funcnum = 0;; funcnum++)
		{
			if (strcasecmp(crule_funclist[funcnum].name, funcname) == 0)
				break;
			if (crule_funclist[funcnum].name[0] == '\0')
				return (CR_UNKNWFUNC);
		}
		if ((errcode = crule_gettoken(next_tokp, ruleptr)) != CR_NOERR)
			return (errcode);
		*funcrootp = (crule_treeptr) safe_alloc(sizeof(crule_treeelem));
#ifdef CR_DEBUG
		(void)fprintf(stderr, "allocating function element at %ld\n",
		    *funcrootp);
#endif
		(*funcrootp)->funcptr = NULL;	/* for freeing aborted trees */
		if ((errcode = crule_parsearglist(*funcrootp, next_tokp,
		    ruleptr)) != CR_NOERR)
			return (errcode);
		if (*next_tokp != CR_CLOSEPAREN)
			return (CR_EXPCTCLOSE);
		if ((crule_funclist[funcnum].reqnumargs !=
		    (*funcrootp)->numargs)
		    && (crule_funclist[funcnum].reqnumargs != -1))
			return (CR_ARGMISMAT);
		if ((errcode = crule_gettoken(next_tokp, ruleptr)) != CR_NOERR)
			return (errcode);
		(*funcrootp)->funcptr = crule_funclist[funcnum].funcptr;
		return (CR_NOERR);
	}
	else
		return (CR_EXPCTOPEN);
}

int  crule_parsearglist(crule_treeptr argrootp, int *next_tokp, char **ruleptr)
{
	int  errcode = CR_NOERR;
	char *argelemp = NULL;
	char currarg[CR_MAXARGLEN];
	int  arglen = 0;
	char word[CR_MAXARGLEN];
	int  wordlen = 0;

	argrootp->numargs = 0;
	currarg[0] = '\0';
	while (errcode == CR_NOERR)
	{
		switch (*next_tokp)
		{
		  case CR_WORD:
			  crule_getword(word, &wordlen, CR_MAXARGLEN, ruleptr);
			  if (currarg[0] != '\0')
			  {
				  if ((arglen + wordlen) < (CR_MAXARGLEN - 1))
				  {
					  strlcat(currarg, " ", sizeof currarg);
					  strlcat(currarg, word, sizeof currarg);
					  arglen += wordlen + 1;
				  }
			  }
			  else
			  {
				  strlcpy(currarg, word, sizeof currarg);
				  arglen = wordlen;
			  }
			  errcode = crule_gettoken(next_tokp, ruleptr);
			  break;
		  default:
#if !defined(CR_DEBUG) && !defined(CR_CHKCONF)
			  collapse(currarg);
#endif
			  if (*currarg)
			  {
				  safe_strdup(argelemp, currarg);
				  argrootp->arg[argrootp->numargs++] = (void *)argelemp;
			  }
			  if (*next_tokp != CR_COMMA)
				  return (CR_NOERR);
			  currarg[0] = '\0';
			  errcode = crule_gettoken(next_tokp, ruleptr);
			  break;
		}
	}
	return (errcode);
}

/*
 * this function is recursive..  i wish i knew a nonrecursive way but
 * i dont.  anyway, recursion is fun..  :)
 * DO NOT CALL THIS FUNTION WITH A POINTER TO A NULL POINTER
 * (ie: if *elem is NULL, you're doing it wrong - seg fault)
 */
void crule_free(char **elem)
{
	int  arg, numargs;

	if ((*((crule_treeptr *) elem))->funcptr == crule__not)
	{
		/* type conversions and ()'s are fun! ;)  here have an asprin.. */
		if ((*((crule_treeptr *) elem))->arg[0] != NULL)
			crule_free((char **)&((*((crule_treeptr *)
			    elem))->arg[0]));
	}
	else if ((*((crule_treeptr *) elem))->funcptr == crule__andor)
	{
		crule_free((char **)&((*((crule_treeptr *) elem))->arg[0]));
		if ((*((crule_treeptr *) elem))->arg[1] != NULL)
			crule_free((char **)&((*((crule_treeptr *)
			    elem))->arg[1]));
	}
	else
	{
		numargs = (*((crule_treeptr *) elem))->numargs;
		for (arg = 0; arg < numargs; arg++)
			safe_free_raw((char *)(*((crule_treeptr *) elem))->arg[arg]);
	}
#ifdef CR_DEBUG
	(void)fprintf(stderr, "freeing element at %ld\n", *elem);
#endif
	safe_free(*elem);
	*elem = NULL;
}

char *crule_errstring(int errcode)
{
	return crule_errstr[errcode-1];
}

int crule_test(char *rule)
{
	char *ruleptr = rule;
	int  next_tok;
	crule_treeptr ruleroot = NULL;
	int  errcode = CR_NOERR;

	if ((errcode = crule_gettoken(&next_tok, &ruleptr)) == CR_NOERR) {
		if ((errcode = crule_parseorexpr(&ruleroot, &next_tok,
		    &ruleptr)) == CR_NOERR) {
			if (ruleroot != NULL) {
				if (next_tok == CR_END)
				{
					crule_free((char **)&ruleroot);
					return 0;
				}
				else
					errcode = CR_UNEXPCTTOK;
			}
			else
				errcode = CR_EXPCTOR;
		}
	}
	if (ruleroot != NULL)
		crule_free((char **)&ruleroot);
	return errcode+1;
}

#ifdef CR_DEBUG
void print_tree(crule_treeptr printelem)
{
	int  funcnum, arg;

	if (printelem->funcptr == crule__not)
	{
		printf("!( ");
		print_tree((crule_treeptr) printelem->arg[0]);
		printf(") ");
	}
	else if (printelem->funcptr == crule__andor)
	{
		printf("( ");
		print_tree((crule_treeptr) printelem->arg[0]);
		if (printelem->arg[2])
			printf("|| ");
		else
			printf("&& ");
		print_tree((crule_treeptr) printelem->arg[1]);
		printf(") ");
	}
	else
	{
		for (funcnum = 0;; funcnum++)
		{
			if (printelem->funcptr ==
			    crule_funclist[funcnum].funcptr)
				break;
			if (crule_funclist[funcnum].funcptr == NULL)
			{
				printf("\nACK!  *koff*  *sputter*\n");
				exit(1);
			}
		}
		printf("%s(", crule_funclist[funcnum].name);
		for (arg = 0; arg < printelem->numargs; arg++)
		{
			if (arg != 0)
				printf(",");
			printf("%s", (char *)printelem->arg[arg]);
		}
		printf(") ");
	}
}

#endif

#ifdef CR_DEBUG
void main()
{
	char indata[256];
	char *rule;

	printf("rule: ");
	while (fgets(indata, 256, stdin) != NULL)
	{
		indata[strlen(indata) - 1] = '\0';	/* lose the newline */
		if ((rule = crule_parse(indata)) != NULL)
		{
			printf("equivalent rule: ");
			print_tree((crule_treeptr) rule);
			printf("\n");
			crule_free(&rule);
		}
		printf("\nrule: ");
	}
	printf("\n");
}
#endif