source: trunk/libs/newlib/src/newlib/libc/sys/linux/net/rcmd.c @ 444

/*
 * Copyright (C) 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
/*
 * Copyright (c) 1983, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)rcmd.c      8.3 (Berkeley) 3/26/94";
#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>
#include <sys/poll.h>
#include <sys/socket.h>
#include <sys/stat.h>

#include <netinet/in.h>
#include <arpa/inet.h>

#include <alloca.h>
#include <signal.h>
#include <fcntl.h>
#include <netdb.h>
#include <unistd.h>
#include <pwd.h>
#include <errno.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <ctype.h>
#include <string.h>
#include <libintl.h>
#include <stdlib.h>
#include <wchar.h>
#include <sys/uio.h>

#include "local.h"


int __ivaliduser (FILE *, u_int32_t, const char *, const char *);
static int __validuser2_sa (FILE *, struct sockaddr *, size_t,
                            const char *, const char *, const char *);
static int ruserok2_sa (struct sockaddr *ra, size_t ralen,
                        int superuser, const char *ruser,
                        const char *luser, const char *rhost);
static int ruserok_sa (struct sockaddr *ra, size_t ralen,
                        int superuser, const char *ruser,
                        const char *luser);
int iruserok_af (const void *raddr, int superuser, const char *ruser,
                 const char *luser, sa_family_t af);
int iruserok (u_int32_t raddr, int superuser, const char *ruser,
              const char *luser);

libc_hidden_proto (iruserok_af)

libc_freeres_ptr(static char *ahostbuf);

int
rcmd_af(ahost, rport, locuser, remuser, cmd, fd2p, af)
        char **ahost;
        u_short rport;
        const char *locuser, *remuser, *cmd;
        int *fd2p;
        sa_family_t af;
{
        char paddr[INET6_ADDRSTRLEN];
        struct addrinfo hints, *res, *ai;
        struct sockaddr_storage from;
        struct pollfd pfd[2];
        int32_t oldmask;
        pid_t pid;
        int s, lport, timo, error;
        char c;
        int refused;
        char num[8];
        ssize_t n;

        if (af != AF_INET && af != AF_INET6 && af != AF_UNSPEC)
          {
            __set_errno (EAFNOSUPPORT);
            return -1;
          }

        pid = __getpid();

        memset(&hints, '\0', sizeof(hints));
        hints.ai_flags = AI_CANONNAME;
        hints.ai_family = af;
        hints.ai_socktype = SOCK_STREAM;
        (void)snprintf(num, sizeof(num), "%d", ntohs(rport));
        error = getaddrinfo(*ahost, num, &hints, &res);
        if (error) {
                if (error == EAI_NONAME && *ahost != NULL) {
                        if (_IO_fwide (stderr, 0) > 0)
                                __fwprintf(stderr, L"%s: Unknown host\n",
                                           *ahost);
                        else
                                fprintf(stderr, "%s: Unknown host\n", *ahost);
                } else {
                        if (_IO_fwide (stderr, 0) > 0)
                                __fwprintf(stderr, L"rcmd: getaddrinfo: %s\n",
                                           gai_strerror(error));
                        else
                                fprintf(stderr, "rcmd: getaddrinfo: %s\n",
                                        gai_strerror(error));
                }
                return (-1);
        }

        pfd[0].events = POLLIN;
        pfd[1].events = POLLIN;

        if (res->ai_canonname){
                free (ahostbuf);
                ahostbuf = strdup (res->ai_canonname);
                if (ahostbuf == NULL) {
                        if (_IO_fwide (stderr, 0) > 0)
                                __fwprintf(stderr, L"%s",
                                           _("rcmd: Cannot allocate memory\n"));
                        else
                                fputs(_("rcmd: Cannot allocate memory\n"),
                                      stderr);
                        return (-1);
                }
                *ahost = ahostbuf;
        } else
                *ahost = NULL;
        ai = res;
        refused = 0;
        oldmask = __sigblock(sigmask(SIGURG));
        for (timo = 1, lport = IPPORT_RESERVED - 1;;) {
                char errbuf[200];

                s = rresvport_af(&lport, ai->ai_family);
                if (s < 0) {
                        if (errno == EAGAIN) {
                                if (_IO_fwide (stderr, 0) > 0)
                                        __fwprintf(stderr, L"%s",
                                                   _("rcmd: socket: All ports in use\n"));
                                else
                                        fputs(_("rcmd: socket: All ports in use\n"),
                                              stderr);
                        } else {
                                if (_IO_fwide (stderr, 0) > 0)
                                        __fwprintf(stderr,
                                                   L"rcmd: socket: %m\n");
                                else
                                        fprintf(stderr, "rcmd: socket: %m\n");
                        }
                        __sigsetmask(oldmask);
                        freeaddrinfo(res);
                        return -1;
                }
                __fcntl(s, F_SETOWN, pid);
                if (__connect(s, ai->ai_addr, ai->ai_addrlen) >= 0)
                        break;
                (void)__close(s);
                if (errno == EADDRINUSE) {
                        lport--;
                        continue;
                }
                if (errno == ECONNREFUSED)
                        refused = 1;
                if (ai->ai_next != NULL) {
                        int oerrno = errno;
                        char *buf = NULL;

                        getnameinfo(ai->ai_addr, ai->ai_addrlen,
                                    paddr, sizeof(paddr),
                                    NULL, 0,
                                    NI_NUMERICHOST);

                        if (__asprintf (&buf, _("connect to address %s: "),
                                        paddr) >= 0)
                          {
                            if (_IO_fwide (stderr, 0) > 0)
                              __fwprintf(stderr, L"%s", buf);
                            else
                              fputs (buf, stderr);
                            free (buf);
                          }
                        __set_errno (oerrno);
                        perror(0);
                        ai = ai->ai_next;
                        getnameinfo(ai->ai_addr, ai->ai_addrlen,
                                    paddr, sizeof(paddr),
                                    NULL, 0,
                                    NI_NUMERICHOST);
                        if (__asprintf (&buf, _("Trying %s...\n"), paddr) >= 0)
                          {
                            if (_IO_fwide (stderr, 0) > 0)
                              __fwprintf (stderr, L"%s", buf);
                            else
                              fputs (buf, stderr);
                            free (buf);
                          }
                        continue;
                }
                if (refused && timo <= 16) {
                        (void)sleep(timo);
                        timo *= 2;
                        ai = res;
                        refused = 0;
                        continue;
                }
                freeaddrinfo(res);
                if (_IO_fwide (stderr, 0) > 0)
                        (void)__fwprintf(stderr, L"%s: %s\n", *ahost,
                                         strerror_r(errno,
                                                      errbuf, sizeof (errbuf)));
                else
                        (void)fprintf(stderr, "%s: %s\n", *ahost,
                                      strerror_r(errno,
                                                   errbuf, sizeof (errbuf)));
                __sigsetmask(oldmask);
                return -1;
        }
        lport--;
        if (fd2p == 0) {
                __write(s, "", 1);
                lport = 0;
        } else {
                char num[8];
                int s2 = rresvport_af(&lport, ai->ai_family), s3;
                socklen_t len = ai->ai_addrlen;

                if (s2 < 0)
                        goto bad;
                listen(s2, 1);
                (void)snprintf(num, sizeof(num), "%d", lport);
                if (__write(s, num, strlen(num)+1) != (ssize_t)strlen(num)+1) {
                        char *buf = NULL;

                        if (__asprintf (&buf, _("\
rcmd: write (setting up stderr): %m\n")) >= 0)
                          {
                            if (_IO_fwide (stderr, 0) > 0)
                              __fwprintf(stderr, L"%s", buf);
                            else
                              fputs (buf, stderr);
                            free (buf);
                          }
                        (void)__close(s2);
                        goto bad;
                }
                pfd[0].fd = s;
                pfd[1].fd = s2;
                __set_errno (0);
                if (__poll (pfd, 2, -1) < 1 || (pfd[1].revents & POLLIN) == 0){
                        char *buf = NULL;

                        if ((errno != 0
                             && __asprintf(&buf, _("\
rcmd: poll (setting up stderr): %m\n")) >= 0)
                            || (errno == 0
                                && __asprintf(&buf, _("\
poll: protocol failure in circuit setup\n")) >= 0))
                          {
                            if (_IO_fwide (stderr, 0) > 0)
                              __fwprintf (stderr, L"%s", buf);
                            else
                              fputs (buf, stderr);
                            free  (buf);
                          }
                        (void)__close(s2);
                        goto bad;
                }
                s3 = TEMP_FAILURE_RETRY (accept(s2, (struct sockaddr *)&from,
                                                &len));
                switch (from.ss_family) {
                case AF_INET:
                        rport = ntohs(((struct sockaddr_in *)&from)->sin_port);
                        break;
                case AF_INET6:
                        rport = ntohs(((struct sockaddr_in6 *)&from)->sin6_port);
                        break;
                default:
                        rport = 0;
                        break;
                }
                (void)__close(s2);
                if (s3 < 0) {
                        if (_IO_fwide (stderr, 0) > 0)
                                (void)__fwprintf(stderr,
                                                 L"rcmd: accept: %m\n");
                        else
                                (void)fprintf(stderr,
                                              "rcmd: accept: %m\n");
                        lport = 0;
                        goto bad;
                }
                *fd2p = s3;

                if (rport >= IPPORT_RESERVED || rport < IPPORT_RESERVED / 2){
                        char *buf = NULL;

                        if (__asprintf(&buf, _("\
socket: protocol failure in circuit setup\n")) >= 0)
                          {
                            if (_IO_fwide (stderr, 0) > 0)
                              __fwprintf (stderr, L"%s", buf);
                            else
                              fputs (buf, stderr);
                            free (buf);
                          }
                        goto bad2;
                }
        }
        struct iovec iov[3] =
          {
            [0] = { .iov_base = (void *) locuser,
                    .iov_len = strlen (locuser) + 1 },
            [1] = { .iov_base = (void *) remuser,
                    .iov_len = strlen (remuser) + 1 },
            [2] = { .iov_base = (void *) cmd,
                    .iov_len = strlen (cmd) + 1 }
          };
        (void) TEMP_FAILURE_RETRY (writev (s, iov, 3));
        n = TEMP_FAILURE_RETRY (read(s, &c, 1));
        if (n != 1) {
                char *buf = NULL;

                if ((n == 0
                     && asprintf(&buf, _("rcmd: %s: short read"),
                                   *ahost) >= 0)
                    || (n != 0
                        && asprintf(&buf, "rcmd: %s: %m\n", *ahost) >= 0))
                  {
                    if (_IO_fwide (stderr, 0) > 0)
                      __fwprintf (stderr, L"%s", buf);
                    else
                      fputs (buf, stderr);
                    free (buf);
                  }
                goto bad2;
        }
        if (c != 0) {
                while (__read(s, &c, 1) == 1) {
                        (void)__write(STDERR_FILENO, &c, 1);
                        if (c == '\n')
                                break;
                }
                goto bad2;
        }
        __sigsetmask(oldmask);
        freeaddrinfo(res);
        return s;
bad2:
        if (lport)
                (void)__close(*fd2p);
bad:
        (void)__close(s);
        __sigsetmask(oldmask);
        freeaddrinfo(res);
        return -1;
}
libc_hidden_def (rcmd_af)

int
rcmd(ahost, rport, locuser, remuser, cmd, fd2p)
        char **ahost;
        u_short rport;
        const char *locuser, *remuser, *cmd;
        int *fd2p;
{
  return rcmd_af (ahost, rport, locuser, remuser, cmd, fd2p, AF_INET);
}

int
rresvport_af(alport, family)
        int *alport;
        sa_family_t family;
{
        struct sockaddr_storage ss;
        int s;
        size_t len;
        uint16_t *sport;

        switch(family){
        case AF_INET:
                len = sizeof(struct sockaddr_in);
                sport = &((struct sockaddr_in *)&ss)->sin_port;
                break;
        case AF_INET6:
                len = sizeof(struct sockaddr_in6);
                sport = &((struct sockaddr_in6 *)&ss)->sin6_port;
                break;
        default:
                __set_errno (EAFNOSUPPORT);
                return -1;
        }
        s = __socket(family, SOCK_STREAM, 0);
        if (s < 0)
                return -1;

        memset (&ss, '\0', sizeof(ss));
#ifdef SALEN
        ss.__ss_len = len;
#endif
        ss.ss_family = family;

        /* Ignore invalid values.  */
        if (*alport < IPPORT_RESERVED / 2)
                *alport = IPPORT_RESERVED / 2;
        else if (*alport >= IPPORT_RESERVED)
                *alport = IPPORT_RESERVED - 1;

        int start = *alport;
        do {
                *sport = htons((uint16_t) *alport);
                if (__bind(s, (struct sockaddr *)&ss, len) >= 0)
                        return s;
                if (errno != EADDRINUSE) {
                        (void)__close(s);
                        return -1;
                }
                if ((*alport)-- == IPPORT_RESERVED/2)
                        *alport = IPPORT_RESERVED - 1;
        } while (*alport != start);
        (void)__close(s);
        __set_errno (EAGAIN);
        return -1;
}
libc_hidden_def (rresvport_af)

int
rresvport(alport)
        int *alport;
{
        return rresvport_af(alport, AF_INET);
}

int     __check_rhosts_file = 1;
char    *__rcmd_errstr;

int
ruserok_af(rhost, superuser, ruser, luser, af)
        const char *rhost, *ruser, *luser;
        int superuser;
        sa_family_t af;
{
        struct addrinfo hints, *res, *res0;
        int gai;
        int ret;

        memset (&hints, '\0', sizeof(hints));
        hints.ai_family = af;
        gai = getaddrinfo(rhost, NULL, &hints, &res0);
        if (gai)
                return -1;
        ret = -1;
        for (res=res0; res; res=res->ai_next)
                if (ruserok2_sa(res->ai_addr, res->ai_addrlen,
                                superuser, ruser, luser, rhost) == 0){
                        ret = 0;
                        break;
                }
        freeaddrinfo(res0);
        return (ret);
}
libc_hidden_def (ruserok_af)

int
ruserok(rhost, superuser, ruser, luser)
        const char *rhost, *ruser, *luser;
        int superuser;
{
        return ruserok_af(rhost, superuser, ruser, luser, AF_INET);
}

/* Extremely paranoid file open function. */
static FILE *
iruserfopen (const char *file, uid_t okuser)
{
  struct stat64 st;
  char *cp = NULL;
  FILE *res = NULL;

  /* If not a regular file, if owned by someone other than user or
     root, if writeable by anyone but the owner, or if hardlinked
     anywhere, quit.  */
  cp = NULL;
  if (__lxstat64 (_STAT_VER, file, &st))
    cp = _("lstat failed");
  else if (!S_ISREG (st.st_mode))
    cp = _("not regular file");
  else
    {
      res = fopen (file, "rc");
      if (!res)
        cp = _("cannot open");
      else if (__fxstat64 (_STAT_VER, fileno (res), &st) < 0)
        cp = _("fstat failed");
      else if (st.st_uid && st.st_uid != okuser)
        cp = _("bad owner");
      else if (st.st_mode & (S_IWGRP|S_IWOTH))
        cp = _("writeable by other than owner");
      else if (st.st_nlink > 1)
        cp = _("hard linked somewhere");
    }

  /* If there were any problems, quit.  */
  if (cp != NULL)
    {
      __rcmd_errstr = cp;
      if (res)
        fclose (res);
      return NULL;
    }

  /* No threads use this stream.  */
  __fsetlocking (res, FSETLOCKING_BYCALLER);

  return res;
}

/*
 * New .rhosts strategy: We are passed an ip address. We spin through
 * hosts.equiv and .rhosts looking for a match. When the .rhosts only
 * has ip addresses, we don't have to trust a nameserver.  When it
 * contains hostnames, we spin through the list of addresses the nameserver
 * gives us and look for a match.
 *
 * Returns 0 if ok, -1 if not ok.
 */
static int
ruserok2_sa (ra, ralen, superuser, ruser, luser, rhost)
     struct sockaddr *ra;
     size_t ralen;
     int superuser;
     const char *ruser, *luser, *rhost;
{
  FILE *hostf = NULL;
  int isbad = -1;

  if (!superuser)
    hostf = iruserfopen (_PATH_HEQUIV, 0);

  if (hostf)
    {
      isbad = __validuser2_sa (hostf, ra, ralen, luser, ruser, rhost);
      fclose (hostf);

      if (!isbad)
        return 0;
    }

  if (__check_rhosts_file || superuser)
    {
      char *pbuf;
      struct passwd pwdbuf, *pwd;
      size_t dirlen;
      size_t buflen = __sysconf (_SC_GETPW_R_SIZE_MAX);
      char *buffer = __alloca (buflen);
      uid_t uid;

      if (__getpwnam_r (luser, &pwdbuf, buffer, buflen, &pwd) != 0
          || pwd == NULL)
        return -1;

      dirlen = strlen (pwd->pw_dir);
      pbuf = alloca (dirlen + sizeof "/.rhosts");
      __mempcpy (__mempcpy (pbuf, pwd->pw_dir, dirlen),
                 "/.rhosts", sizeof "/.rhosts");

       /* Change effective uid while reading .rhosts.  If root and
          reading an NFS mounted file system, can't read files that
          are protected read/write owner only.  */
       uid = __geteuid ();
       seteuid (pwd->pw_uid);
       hostf = iruserfopen (pbuf, pwd->pw_uid);

       if (hostf != NULL)
         {
           isbad = __validuser2_sa (hostf, ra, ralen, luser, ruser, rhost);
           fclose (hostf);
         }

       seteuid (uid);
       return isbad;
    }
  return -1;
}
/*
 * ruserok_sa() is now discussed on ipng, so
 * currently disabled for external use
 */
static int ruserok_sa(ra, ralen, superuser, ruser, luser)
     struct sockaddr *ra;
     size_t ralen;
     int superuser;
     const char *ruser, *luser;
{
  return ruserok2_sa(ra, ralen, superuser, ruser, luser, "-");
}

/* This is the exported version.  */
int
iruserok_af (raddr, superuser, ruser, luser, af)
     const void *raddr;
     int superuser;
     const char *ruser, *luser;
     sa_family_t af;
{
  struct sockaddr_storage ra;
  size_t ralen;

  memset (&ra, '\0', sizeof(ra));
  switch (af){
  case AF_INET:
    ((struct sockaddr_in *)&ra)->sin_family = AF_INET;
    memcpy (&(((struct sockaddr_in *)&ra)->sin_addr), raddr,
            sizeof(struct in_addr));
    ralen = sizeof(struct sockaddr_in);
    break;
  case AF_INET6:
    ((struct sockaddr_in6 *)&ra)->sin6_family = AF_INET6;
    memcpy (&(((struct sockaddr_in6 *)&ra)->sin6_addr), raddr,
            sizeof(struct in6_addr));
    ralen = sizeof(struct sockaddr_in6);
    break;
  default:
    return 0;
  }
  return ruserok_sa ((struct sockaddr *)&ra, ralen, superuser, ruser, luser);
}
libc_hidden_def (iruserok_af)

int
iruserok (raddr, superuser, ruser, luser)
     u_int32_t raddr;
     int superuser;
     const char *ruser, *luser;
{
  return iruserok_af (&raddr, superuser, ruser, luser, AF_INET);
}

/*
 * XXX
 * Don't make static, used by lpd(8).
 *
 * This function is not used anymore. It is only present because lpd(8)
 * calls it (!?!). We simply call __invaliduser2() with an illegal rhost
 * argument. This means that netgroups won't work in .rhost/hosts.equiv
 * files. If you want lpd to work with netgroups, fix lpd to use ruserok()
 * or PAM.
 * Returns 0 if ok, -1 if not ok.
 */
int
__ivaliduser(hostf, raddr, luser, ruser)
        FILE *hostf;
        u_int32_t raddr;
        const char *luser, *ruser;
{
        struct sockaddr_in ra;
        memset(&ra, '\0', sizeof(ra));
        ra.sin_family = AF_INET;
        ra.sin_addr.s_addr = raddr;
        return __validuser2_sa(hostf, (struct sockaddr *)&ra, sizeof(ra),
                               luser, ruser, "-");
}


/* Returns 1 on positive match, 0 on no match, -1 on negative match.  */
static int
internal_function
__checkhost_sa (struct sockaddr *ra, size_t ralen, char *lhost,
                const char *rhost)
{
        struct addrinfo hints, *res0, *res;
        char raddr[INET6_ADDRSTRLEN];
        int match;
        int negate=1;    /* Multiply return with this to get -1 instead of 1 */

        /* Check nis netgroup.  */
        if (strncmp ("+@", lhost, 2) == 0)
                return innetgr (&lhost[2], rhost, NULL, NULL);

        if (strncmp ("-@", lhost, 2) == 0)
                return -innetgr (&lhost[2], rhost, NULL, NULL);

        /* -host */
        if (strncmp ("-", lhost,1) == 0) {
                negate = -1;
                lhost++;
        } else if (strcmp ("+",lhost) == 0) {
                return 1;                    /* asking for trouble, but ok.. */
        }

        /* Try for raw ip address first. */
        /* XXX */
        if (getnameinfo(ra, ralen,
                        raddr, sizeof(raddr), NULL, 0,
                        NI_NUMERICHOST) == 0
            && strcmp(raddr, lhost) == 0)
                return negate;

        /* Better be a hostname. */
        match = 0;
        memset(&hints, '\0', sizeof(hints));
        hints.ai_family = ra->sa_family;
        if (getaddrinfo(lhost, NULL, &hints, &res0) == 0){
                /* Spin through ip addresses. */
                for (res = res0; res; res = res->ai_next)
                  {
                    if (res->ai_family == ra->sa_family
                        && !memcmp(res->ai_addr, ra, res->ai_addrlen))
                      {
                        match = 1;
                        break;
                      }
                  }
                freeaddrinfo (res0);
        }
        return negate * match;
}

/* Returns 1 on positive match, 0 on no match, -1 on negative match.  */
static int
internal_function
__icheckuser (const char *luser, const char *ruser)
{
    /*
      luser is user entry from .rhosts/hosts.equiv file
      ruser is user id on remote host
      */

    /* [-+]@netgroup */
    if (strncmp ("+@", luser, 2) == 0)
        return innetgr (&luser[2], NULL, ruser, NULL);

    if (strncmp ("-@", luser,2) == 0)
        return -innetgr (&luser[2], NULL, ruser, NULL);

    /* -user */
    if (strncmp ("-", luser, 1) == 0)
        return -(strcmp (&luser[1], ruser) == 0);

    /* + */
    if (strcmp ("+", luser) == 0)
        return 1;

    /* simple string match */
    return strcmp (ruser, luser) == 0;
}

/*
 * Returns 1 for blank lines (or only comment lines) and 0 otherwise
 */
static int
__isempty (char *p)
{
    while (*p && isspace (*p)) {
        ++p;
    }

    return (*p == '\0' || *p == '#') ? 1 : 0 ;
}

/*
 * Returns 0 if positive match, -1 if _not_ ok.
 */
static int
__validuser2_sa(hostf, ra, ralen, luser, ruser, rhost)
        FILE *hostf;
        struct sockaddr *ra;
        size_t ralen;
        const char *luser, *ruser, *rhost;
{
    register const char *user;
    register char *p;
    int hcheck, ucheck;
    char *buf = NULL;
    size_t bufsize = 0;
    int retval = -1;

    while (__getline (&buf, &bufsize, hostf) > 0) {
        buf[bufsize - 1] = '\0'; /* Make sure it's terminated.  */
        p = buf;

        /* Skip empty or comment lines */
        if (__isempty (p)) {
            continue;
        }

        for (;*p && !isspace(*p); ++p) {
            *p = _tolower (*p);
        }

        /* Next we want to find the permitted name for the remote user.  */
        if (*p == ' ' || *p == '\t') {
            /* <nul> terminate hostname and skip spaces */
            for (*p++='\0'; *p && isspace (*p); ++p);

            user = p;                   /* this is the user's name */
            while (*p && !isspace (*p))
                ++p;                    /* find end of user's name */
        } else
            user = p;

        *p = '\0';              /* <nul> terminate username (+host?) */

        /* buf -> host(?) ; user -> username(?) */

        /* First check host part */
        hcheck = __checkhost_sa (ra, ralen, buf, rhost);

        if (hcheck < 0)
            break;

        if (hcheck) {
            /* Then check user part */
            if (! (*user))
                user = luser;

            ucheck = __icheckuser (user, ruser);

            /* Positive 'host user' match? */
            if (ucheck > 0) {
                retval = 0;
                break;
            }

            /* Negative 'host -user' match? */
            if (ucheck < 0)
                break;

            /* Neither, go on looking for match */
        }
    }

    if (buf != NULL)
      free (buf);

    return retval;
}