inetutils/ftpd/conf.c

/*
  Copyright (C) 2000-2025 Free Software Foundation, Inc.

  This file is part of GNU Inetutils.

  GNU Inetutils is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or (at
  your option) any later version.

  GNU Inetutils is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program.  If not, see `http://www.gnu.org/licenses/'. */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <ctype.h>
#include <pwd.h>
#include <grp.h>
#include <mgetgroups.h>
#include "extern.h"

#ifndef LINE_MAX
# define LINE_MAX 2048
#endif

int
display_file (const char *name, int code)
{
  char *cp, line[LINE_MAX];
  FILE *fp = fopen (name, "r");
  if (fp != NULL)
    {
      while (fgets (line, sizeof (line), fp) != NULL)
	{
	  cp = strchr (line, '\n');
	  if (cp != NULL)
	    *cp = '\0';
	  lreply (code, "%s", line);
	}
      fflush (stdout);
      fclose (fp);
      return 0;
    }
  return errno;
}

/*
 * Check if a user is in the file `filename',
 * typically PATH_FTPUSERS or PATH_FTPCHROOT.
 * Return 1 if yes, 0 otherwise.
 */
int
checkuser (const char *filename, const char *name)
{
  FILE *fp;
  int found = 0, ngroups = 0;
  char *p, line[BUFSIZ];
  gid_t *groups = NULL;
  struct passwd *pwd = NULL;

  fp = fopen (filename, "r");
  if (fp != NULL)
    {
      while (fgets (line, sizeof (line), fp) != NULL)
	{
	  /* Properly terminate input.  */
	  p = strchr (line, '\n');
	  if (p != NULL)
	    *p = '\0';

	  /* Disregard initial blank characters.  */
	  p = line;
	  while (isblank (*p))
	    p++;

	  /* Skip comments, and empty lines.  */
	  if (*p == '#' || *p == 0)
	    continue;

	  /* Wildcard entry, a single '@'.  */
	  if (p[0] == '@' && (p[1] == 0 || isblank (p[1])))
	    {
	      found = 1;
	      break;
	    }

	  /* Group entries begin with '@' and are non-trivial.  */
	  if (p[0] == '@' && p[1] && !isblank (p[1]))
	    {
	      /* The group list is generated only if needed,
	       * and only once.
	       */
	      if (!groups)
		{
		  pwd = getpwnam (name);
		  if (pwd)
		    ngroups = mgetgroups (name, pwd->pw_gid, &groups);
		}

	      /* Check for group membership.  */
	      if ((ngroups > 0) && groups && pwd)
		{
		  struct group *grp;
		  char *gname;

		  /* Identify valid group name.  */
		  gname = ++p;
		  while (*p && (isalnum (*p) || *p == '_' || *p == '-'))
		    p++;

		  *p = '\0';	/* Group name ends here.  */

		  grp = getgrnam (gname);
		  if (grp)
		    {
		      int j;

		      for (j = 0; j < ngroups; j++)
			if (groups[j] == grp->gr_gid)
			  {
			    found = 1;
			    break;
			  }
		    }
		}
	      continue;		/* No match, or failure.  */
	    }

	  /* User name ends at the first blank character.  */
	  if (strncmp (p, name, strlen (name)) == 0
	      && (p[strlen (name)] == 0 || isblank (p[strlen (name)])))
	    {
	      found = 1;
	      break;
	    }
	}
      free (groups);
      fclose (fp);
    }
  return (found);
}