svc/tripe-ifup.in: Trim prefix length from IPv6 address used as gateway.

[tripe] / common / util.c

/* -*-c-*-
 *
 * Utilities for the client and the server
 *
 * (c) 2001 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------*
 *
 * This file is part of Trivial IP Encryption (TrIPE).
 *
 * TrIPE 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 2 of the License, or
 * (at your option) any later version.
 *
 * TrIPE 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 TrIPE; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/*----- Header files ------------------------------------------------------*/

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <sys/types.h>
#include <unistd.h>

#include <pwd.h>
#include <grp.h>

#include <mLib/dstr.h>
#include <mLib/report.h>

#include "util.h"

/*----- Main code ---------------------------------------------------------*/

/* --- @u_quotify@ --- *
 *
 * Arguments:	@dstr *d@ = where to write the answer
 *		@const char *p@ = string to quotify
 *
 * Returns:	---
 *
 * Use:		Quotes the given string if necessary, according to our
 *		quoting rules.
 */

void u_quotify(dstr *d, const char *p)
{
  if (d->len)
    dstr_putc(d, ' ');
  if (*p && !p[strcspn(p, "\"' \t\n\v")])
    dstr_puts(d, p);
  else {
    dstr_putc(d, '\"');
    while (*p) {
      if (*p == '\\' || *p == '\"')
	dstr_putc(d, '\\');
      dstr_putc(d, *p++);
    }
    dstr_putc(d, '\"');
  }
}

/* --- @u_getuser@ --- *
 *
 * Arguments:	@const char *name@ = user name or id requested
 *		@gid_t *gg@ = where to store corresponding gid
 *
 * Returns:	Corresponding uid.
 *
 * Use:		Resolves a user name into a uid.  Dies on failure; suitable
 *		for use in argument parsing.
 */

uid_t u_getuser(const char *name, gid_t *gg)
{
  struct passwd *pw;
  char *p;
  unsigned long i = strtoul(name, &p, 0);

  if (!*p)
    pw = getpwuid(i);
  else
    pw = getpwnam(name);
  if (!pw)
    die(EXIT_FAILURE, "user `%s' not found", name);
  if (gg && *gg == -1)
    *gg = pw->pw_gid;
  return (pw->pw_uid);
}

/* --- @u_getgroup@ --- *
 *
 * Arguments:	@const char *name@ = user name or id requested
 *
 * Returns:	Corresponding gid.
 *
 * Use:		Resolves a group name into a gid.  Dies on failure; suitable
 *		for use in argument parsing.
 */

gid_t u_getgroup(const char *name)
{
  struct group *gr;
  char *p;
  unsigned long i = strtoul(name, &p, 0);

  if (!*p)
    gr = getgrgid(i);
  else
    gr = getgrnam(name);
  if (!gr)
    die(EXIT_FAILURE, "group `%s' not found", name);
  return (gr->gr_gid);
}

/* --- @u_setugid@ --- *
 *
 * Arguments:	@uid_t u@ = user to set
 *		@gid_t g@ = group to set
 *
 * Returns:	---
 *
 * Use:		Sets user and group to the given values; aborts on failure.
 */

void u_setugid(uid_t u, gid_t g)
{
  uid_t cu = geteuid();

  if (cu == 0 && g != (gid_t)-1) {
    if (setgid(g) || (getuid() == 0 && setgroups(1, &g))) {
      die(EXIT_FAILURE, "couldn't setgid to %u: %s",
	  (unsigned)g, strerror(errno));
    }
  }
  if (u != (uid_t)-1) {
    if (setuid(u)) {
      die(EXIT_FAILURE, "couldn't setuid to %u: %s",
	  (unsigned)u, strerror(errno));
    }
  }
}

/*----- That's all, folks -------------------------------------------------*/