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static char rcsid[] = "@(#)$Id: domains.c,v 4.1 90/04/28 22:42:44 syd Exp $";

/*******************************************************************************
 *  The Elm Mail System  -  $Revision: 4.1 $   $State: Exp $
 *
 * 			Copyright (c) 1986, 1987 Dave Taylor
 * 			Copyright (c) 1988, 1989, 1990 USENET Community Trust
 *******************************************************************************
 * Bug reports, patches, comments, suggestions should be sent to:
 *
 *	Syd Weinstein, Elm Coordinator
 *	elm@DSI.COM			dsinc!elm
 *
 *******************************************************************************
 * $Log:	domains.c,v $
 * Revision 4.1  90/04/28  22:42:44  syd
 * checkin of Elm 2.3 as of Release PL0
 * 
 *
 ******************************************************************************/

/** This file contains all the code dealing with the expansion of 
    domain based addresses in Elm.  It uses the file "domains" as
    defined in the sysdefs.h file.

    From a file format and idea in "uumail" - designed by Stan Barber.
**/

#if defined(OPTIMIZE_RETURN) || !defined(DONT_TOUCH_ADDRESSES)

#include <ctype.h>

#include "headers.h"

#ifdef BSD
# undef toupper
# undef tolower
#endif

/** define the various characters that we can encounter after a "%" sign
    in the template file...
**/

#define USERNAME	'U'	/* %U = the name of the remote user */
#define RMTMNAME	'N'	/* %N = the remote machine name     */
#define FULLNAME	'D'	/* %D = %N + domain info given      */
#define NPATH		'R'	/* %R = path to %N from pathalias   */
#define PPATH		'P'	/* %P = path to 'P' from pathalias  */
#define OBSOLETE	'S'	/* %S = (used to be suffix string)  */

/** and finally some characters that are allowed in user/machine names **/

#define okay_others(c)	(c == '-' || c == '^' || c == '$' || c == '_')

/** and some allowed ONLY in the username field **/

#define special_chars(c)	(c == '%' || c == ':')

char *find_path_to(), *expand_domain(), *match_and_expand_domain();
char *strcpy(), *strcat(), *strtok();
void rewind();
	      
open_domain_file()
{
	if ((domainfd = fopen(domains, "r")) == NULL) {
	  dprint(2, (debugfile,"Warning: can't open file %s as domains file\n", 
		domains));
	}
	else {
	  dprint(3, (debugfile, 
            "Opened '%s' as the domain database\n\n", domains));
	}
	
	/* if it fails it'll instantiate domainfd to NULL which is
	   exactly what we want to have happen!! */
}

char *expand_domain(buffer)
char *buffer;
{
	/** Expand the address 'buffer' based on the domain information, 
	    if any.  Returns NULL if it can't expand it for any reason.
	**/

	char name[NLEN], address[NLEN], domain[NLEN];
	char *match_and_expand_domain();

	if (domainfd == NULL) return(NULL);	/* no file present! */

	if (explode(buffer, name, address, domain)) 
	  return( match_and_expand_domain(domain, name, address) );
	else {	/* invalid format - not "user@host.domain" */
	  dprint(2,  (debugfile,
		 "Invalid format for domain expansion: %s (expand_domain)\n", 
		   buffer));
	  return(NULL);
	}
}	

int
explode(buffer, name, address, domain)
char *buffer, *name, *address, *domain;
{
	/** Break buffer, if in format name@machine.domain, into the
	    component parts, otherwise return ZERO and don't worry
	    about the values of the parameters!
	**/
	
	register int i, j = 0;

	/** First get the name... **/

	for (i=0; buffer[i] != '@'; i++) {
	  if (! isalnum(buffer[i]) && ! okay_others(buffer[i]) && ! 
		special_chars(buffer[i]))
	    return(0);			/* invalid character in string! */
	  name[i] = buffer[i];
	}

	name[i++] = '\0';

	/** now let's get the machinename **/

	while (buffer[i] != '.') {
	  if (! isalnum(buffer[i]) && ! okay_others(buffer[i]))
	     return(0);			/* invalid character in string! */
	  address[j++] = buffer[i++];
	}
	address[j] = '\0';

	j = 0;

	/** finally let's get the domain information (there better be some!) **/

	while (buffer[i] != '\0') {
	  if (! isalnum(buffer[i]) && ! okay_others(buffer[i]) && 
	        buffer[i] != '.')
	    return(0);		      /* an you fail again, bozo! */
	  domain[j++] = toupper(buffer[i]);
	  i++;
	}

	domain[j] = '\0';
	
	return(j);		/* if j == 0 there's no domain info! */
}
        
char *match_and_expand_domain(domain, name, machine)
char *domain, *name, *machine;
{
	/** Given the domain, try to find it in the domain file and
   	    if found expand the entry and return the result as a 
	    character string...
	**/

	static char address[SLEN];
	char   buffer[SLEN], domainbuff[NLEN];
	char   field1[NLEN], field2[NLEN], field3[NLEN];
	char   *path, *template, *expanded, *mydomain;
	int    matched = 0, in_percent = 0;
	register int j = 0;

	address[j] = '\0';

	domainbuff[0] = '\0';
	mydomain = (char *) domainbuff;		    /* set up buffer etc */

	do { 
	  rewind(domainfd);		           /* back to ground zero! */

	  if (strlen(mydomain) > 0) {		   /* already in a domain! */
	    mydomain++;		 		      /* skip leading '.' */
	    while (*mydomain != '.' && *mydomain != ',') 
	      mydomain++;	 		      /* next character   */
	    if (*mydomain == ',')
	      return (NULL);  			  /* didn't find domain!  */
	  }
	  else
	    sprintf(mydomain, "%s,", domain);		/* match ENTIRELY! */

	/* whip through file looking for the entry, please... */

	while (fgets(buffer, SLEN, domainfd) != NULL) {
	  if (buffer[0] == '#')				  /* skip comments */
	    continue;
	  if (strncmp(buffer, mydomain, strlen(mydomain)) == 0) { /* match? */
	     matched++;	/* Gotcha!  Remember this momentous event! */
	     break;
	  }
	}

	if (! matched) 
	   continue;		/* Nothing.  Not a sausage!  Step through! */

	/** We've matched the domain! **/

	no_ret(buffer);

	(void) strtok(buffer, ",");	/* skip the domain info */

	strcpy(field1, strtok(NULL, ","));	/* fun 		*/
	strcpy(field2, strtok(NULL, ","));	/*    stuff     */
	strcpy(field3, strtok(NULL, ","));	/*       eh?    */
	
	path = (char *) NULL;

	/* now we merely need to figure out what permutation this is!
	  
           Fields are null if they have only a blank in them or are null.
           If fields 2 and 3 are null, use field 1 as the template.
            --else--
           If field 3 is null and 2 is not, use field 2 as the template.
            --else--
           Field 3 is the template. */
         

	if (strcmp(field3," ") == 0 || field3[0] == '\0'){
	  if (strcmp(field2," ") == 0 || field2[0] == '\0')
	    template = (char *) field1;
	  else {
	    path     = (char *) field1;
	    template = (char *) field2;
	  }
	}
	else {
	  path     = (char *) field1;
	  template = (char *) field3;
	}
	dprint(1, (debugfile,
	  "-> %s\n-> %s\n-> %s\n", field1, field2, field3));
	dprint(1, (debugfile,
	  "Path-> %s\nTemplate-> %s\n", path, template));

	if (strlen(path) > 0 && path[0] == '>') 
	   path++;	/* skip the '>' character, okay? */

	j = 0;		 	/* address is zero, right now, right?? */
	address[j] = '\0';	      /* make sure string is too! */

	for (; *template; template++) {
	  if (*template == '%') {
	    if (! in_percent)			   /* just hit a NEW percent! */
	      in_percent = 1;
	    else {		  /* just another percent sign on the wall... */
	      address[j++] = '%';
	      address[j] = '\0';		     /* ALWAYS NULL terminate */
	      in_percent = 0;
	    }
	  }
	  else if (in_percent) {	       /* Hey! a real command string */
	    in_percent = 0;
	    switch (*template) {
	      case USERNAME: strcat(address, name);		break;
	      case RMTMNAME: strcat(address, machine);		break;
	      case FULLNAME: strcat(address, machine);
			     strcat(address, domain);		break;
	      case NPATH   : 

		 if ((expanded = find_path_to(machine, FALSE)) == NULL) {
		    dprint(3, (debugfile,
			    "\nCouldn't expand system path '%s' (%s)\n\n",
			    machine, "domains"));
	            error1("Couldn't find a path to %s!", machine);
	            sleep(2);
	            return(NULL);	/* failed!! */
	         }
	         strcat(address, expanded);	/* isn't this fun??? */

	         break;

	      case PPATH   : 

		 if ((expanded = find_path_to(path, FALSE)) == NULL) {
		    dprint(3, (debugfile,
			"\nCouldn't expand system path '%s' (%s)\n\n",
			path, "domains"));
	            error1("Couldn't find a path to %s!", path);
	            sleep(2);
	            return(NULL);	/* failed!! */
	         }
	         strcat(address, expanded);	/* isn't this fun??? */

	         break;

	      case OBSOLETE:	/* fall through.. */
	      default      : dprint(1, (debugfile,
	     "\nError: Bad sequence in template file for domain '%s': %%%c\n\n",
			domain, *template));
	    }
	    j = strlen(address);
	  }
	  else {
	    address[j++] = *template;
	    address[j] = '\0';			/* null terminate */
	  }
	}	

	address[j] = '\0';

	} while (strlen(address) < 1);

	return( (char *) address);
}
#endif
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