/*
   netgroup.c - NSS lookup functions for netgroup entries

   Copyright (C) 2006 West Consulting
   Copyright (C) 2006, 2007, 2008, 2010, 2012, 2013 Arthur de Jong
   Copyright (C) 2010 Symas Corporation

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   This library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301 USA
*/

#include "config.h"

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

#include "prototypes.h"
#include "common.h"
#include "compat/attrs.h"
#include "common/set.h"

/* function for reading a single result entry */
static nss_status_t read_netgrent_line(TFILE *fp, struct __netgrent *result,
                                       char *buffer, size_t buflen, int *errnop)
{
  int32_t tmpint32;
  int type;
  size_t bufptr = 0;
  /* read netgroup type */
  READ_INT32(fp, type);
  if (type == NSLCD_NETGROUP_TYPE_NETGROUP)
  {
    /* the response is a reference to another netgroup */
    result->type = group_val;
    READ_BUF_STRING(fp, result->val.group);
    return NSS_STATUS_SUCCESS;
  }
  else if (type == NSLCD_NETGROUP_TYPE_TRIPLE)
  {
    /* the response is a host/user/domain triple */
    result->type = triple_val;
    /* read host and revert to NULL on empty string */
    READ_BUF_STRING(fp, result->val.triple.host);
#ifdef NSS_FLAVOUR_GLIBC
    if (result->val.triple.host[0] == '\0')
    {
      result->val.triple.host = NULL;
      bufptr--; /* free unused space */
    }
#endif /* NSS_FLAVOUR_GLIBC */
    /* read user and revert to NULL on empty string */
    READ_BUF_STRING(fp, result->val.triple.user);
#ifdef NSS_FLAVOUR_GLIBC
    if (result->val.triple.user[0] == '\0')
    {
      result->val.triple.user = NULL;
      bufptr--; /* free unused space */
    }
#endif /* NSS_FLAVOUR_GLIBC */
    /* read domain and revert to NULL on empty string */
    READ_BUF_STRING(fp, result->val.triple.domain);
#ifdef NSS_FLAVOUR_GLIBC
    if (result->val.triple.domain[0] == '\0')
    {
      result->val.triple.domain = NULL;
      bufptr--; /* free unused space */
    }
#endif /* NSS_FLAVOUR_GLIBC */
    return NSS_STATUS_SUCCESS;
  }
  else if (type == NSLCD_NETGROUP_TYPE_END)
    /* make _nss_ldap_getnetgrent_r() indicate the end of the netgroup */
    return NSS_STATUS_RETURN;
  /* we got something unexpected */
  ERROR_OUT_NOSUCCESS(fp);
  return NSS_STATUS_UNAVAIL;
}

#ifdef NSS_FLAVOUR_GLIBC

/* thread-local file pointer to an ongoing request */
static TLS TFILE *netgrentfp;

/* start a request to get a netgroup by name */
nss_status_t _nss_ldap_setnetgrent(const char *group,
                                   struct __netgrent UNUSED(*result))
{
  /* we cannot use NSS_SETENT() here because we have a parameter that is only
     available in this function */
  int32_t tmpint32;
  int errnocp;
  int *errnop = &errnocp;
  NSS_EXTRA_DEFS
  NSS_AVAILCHECK;
  /* check parameter */
  if ((group == NULL) || (group[0] == '\0'))
    return NSS_STATUS_UNAVAIL;
  /* open a new stream and write the request */
  NSLCD_REQUEST(netgrentfp, NSLCD_ACTION_NETGROUP_BYNAME,
                WRITE_STRING(netgrentfp, group));
  /* read response code */
  READ_RESPONSE_CODE(netgrentfp);
  SKIP_STRING(netgrentfp); /* netgroup name */
  return NSS_STATUS_SUCCESS;
}

/* get a single netgroup tuple from the stream */
nss_status_t _nss_ldap_getnetgrent_r(struct __netgrent *result,
                                     char *buffer, size_t buflen, int *errnop)
{
  nss_status_t retv;
  NSS_EXTRA_DEFS;
  NSS_AVAILCHECK;
  NSS_BUFCHECK;
  /* check that we have a valid file descriptor */
  if (netgrentfp == NULL)
    return NSS_STATUS_UNAVAIL;
  /* prepare for buffer errors */
  tio_mark(netgrentfp);
  /* read a response */
  retv = read_netgrent_line(netgrentfp, result, buffer, buflen, errnop);
  /* check read result */
  if (retv == NSS_STATUS_TRYAGAIN)
  {
    /* if we have a full buffer try to reset the stream */
    if (tio_reset(netgrentfp))
    {
      /* reset failed, we close and give up with a permanent error
         because we cannot retry just the getent() call because it
         may not be only the first entry that failed */
      tio_close(netgrentfp);
      netgrentfp = NULL;
      *errnop = EINVAL;
      return NSS_STATUS_UNAVAIL;
    }
  }
  else if ((retv != NSS_STATUS_SUCCESS) && (retv != NSS_STATUS_RETURN))
    netgrentfp = NULL; /* file should be closed by now */
  return retv;
}

/* close the stream opened with setnetgrent() above */
nss_status_t _nss_ldap_endnetgrent(struct __netgrent UNUSED(*result))
{
  NSS_ENDENT(netgrentfp);
}

#endif /* NSS_FLAVOUR_GLIBC */

#ifdef NSS_FLAVOUR_SOLARIS

/* this is the custom backend structure for the {set,get,end}ent() functions */
struct setnetgrent_backend {
  nss_backend_op_t *ops; /* function-pointer table */
  int n_ops;             /* number of function pointers */
  TFILE *fp;             /* the file pointer for {set,get,end}ent() functions */
  SET *seen_groups;      /* netgroups seen, for loop detection */
  SET *unseen_groups;    /* netgroups that need to be chased */
};

/* easy way to get sets from back-end */
#define NETGROUP_BE(be) ((struct setnetgrent_backend*)(be))

/* access arguments */
#define SETNETGRENT_ARGS(args) ((struct nss_setnetgrent_args *)(args))
#define GETNETGRENT_ARGS(args) ((struct nss_getnetgrent_args *)(args))

/* return a netgroup that has not been traversed */
static char *find_unseen_netgroup(struct setnetgrent_backend *be)
{
  char *group;
  while (1)
  {
    group = set_pop(be->unseen_groups);
    if (group == NULL)
      return NULL;
    if (!set_contains(be->seen_groups, group))
      return group;
  }
}

static nss_status_t start_netgroup_request(struct setnetgrent_backend *be,
                                           const char *group)
{
  /* we cannot use NSS_SETENT() here because we have a parameter that is only
     available in this function */
  int32_t tmpint32;
  int *errnop = &errno;
  /* check parameter */
  if ((group == NULL) || (group[0] == '\0'))
    return NSS_STATUS_UNAVAIL;
  set_add(be->seen_groups, group);
  /* open a new stream and write the request */
  NSLCD_REQUEST(NETGROUP_BE(be)->fp, NSLCD_ACTION_NETGROUP_BYNAME,
                WRITE_STRING(NETGROUP_BE(be)->fp, group));
  /* read response code */
  READ_RESPONSE_CODE(NETGROUP_BE(be)->fp);
  SKIP_STRING(NETGROUP_BE(be)->fp); /* netgroup name */
  return NSS_STATUS_SUCCESS;
}

static nss_status_t netgroup_setnetgrent_setnetgrent(nss_backend_t UNUSED(*be),
                                                     void UNUSED(*args))
{
  return NSS_STATUS_SUCCESS;
}

static nss_status_t netgroup_setnetgrent_getnetgrent(nss_backend_t *be,
                                                     void *args)
{
  struct __netgrent result;
  nss_status_t retv;
  /* check that we have a valid file descriptor */
  if (NETGROUP_BE(be)->fp == NULL)
    return NSS_STATUS_UNAVAIL;
  /* go over the result lines */
  while (1)
  {
    /* prepare for buffer errors */
    tio_mark(NETGROUP_BE(be)->fp);
    /* read single line from the netgroup information */
    retv = read_netgrent_line(NETGROUP_BE(be)->fp, &result, GETNETGRENT_ARGS(args)->buffer,
                              GETNETGRENT_ARGS(args)->buflen, &errno);
    /* check read result */
    if ((retv == NSS_STATUS_SUCCESS) && (result.type == group_val))
    {
      /* a netgroup nested within the current netgroup */
      set_add(NETGROUP_BE(be)->unseen_groups, result.val.group);
    }
    else if ((retv == NSS_STATUS_SUCCESS) && (result.type == triple_val))
    {
      /* a netgroup line we can return */
      GETNETGRENT_ARGS(args)->status = NSS_NETGR_FOUND;
      GETNETGRENT_ARGS(args)->retp[NSS_NETGR_MACHINE] = result.val.triple.host;
      GETNETGRENT_ARGS(args)->retp[NSS_NETGR_USER] = result.val.triple.user;
      GETNETGRENT_ARGS(args)->retp[NSS_NETGR_DOMAIN] = result.val.triple.domain;
      return NSS_STATUS_SUCCESS;
    }
    else if (retv == NSS_STATUS_TRYAGAIN)
    {
      /* we have a full buffer, try to reset the stream */
      if (tio_reset(NETGROUP_BE(be)->fp))
      {
        /* reset failed, we close and give up with a permanent error
           because we cannot retry just the getent() call because it
           may not be only the first entry that failed */
        tio_close(NETGROUP_BE(be)->fp);
        NETGROUP_BE(be)->fp = NULL;
        return NSS_STATUS_UNAVAIL;
      }
      GETNETGRENT_ARGS(args)->status = NSS_NETGR_NOMEM;
      return NSS_STATUS_TRYAGAIN;
    }
    else if (retv == NSS_STATUS_RETURN)
    {
      /* done with the current netgroup */
      tio_close(NETGROUP_BE(be)->fp);
      NETGROUP_BE(be)->fp = NULL;
      /* explore nested netgroups, if any */
      while (retv != NSS_STATUS_SUCCESS)
      {
        /* find a nested netgroup to pursue further */
        char *group = find_unseen_netgroup(NETGROUP_BE(be));
        if (group == NULL)
        {
          /* no more netgroups to explore */
          GETNETGRENT_ARGS(args)->status = NSS_NETGR_NO;
          return NSS_STATUS_SUCCESS;
        }
        /* start a new search with this netgroup */
        retv = start_netgroup_request(NETGROUP_BE(be), group);
        free(group);
      }
    }
    else
    {
      /* some error occurred when reading the line (stream should be closed by now) */
      NETGROUP_BE(be)->fp = NULL;
      GETNETGRENT_ARGS(args)->status = NSS_NETGR_NO;
      return retv;
    }
  }
}

static nss_status_t netgroup_setnetgrent_endnetgrent(nss_backend_t
                                                     UNUSED(*be),
                                                     void UNUSED(*args))
{
  NSS_ENDENT(NETGROUP_BE(be)->fp);
}

static nss_status_t netgroup_setnetgrent_destructor(nss_backend_t *be,
                                                    void *UNUSED(args))
{
  struct setnetgrent_backend *ngbe = (struct setnetgrent_backend *)be;
  if (ngbe->fp != NULL)
    (void)tio_close(ngbe->fp);
  set_free(ngbe->seen_groups);
  set_free(ngbe->unseen_groups);
  free(ngbe);
  return NSS_STATUS_SUCCESS;
}

static nss_backend_op_t netgroup_setnetgrent_ops[] = {
  netgroup_setnetgrent_destructor,
  netgroup_setnetgrent_endnetgrent,
  netgroup_setnetgrent_setnetgrent,
  netgroup_setnetgrent_getnetgrent,
};

static nss_status_t netgroup_setnetgrent_constructor(nss_backend_t *be, void *args)
{
  struct setnetgrent_backend *ngbe;
  nss_status_t retv;
  NSS_AVAILCHECK;
  SETNETGRENT_ARGS(args)->iterator = NULL; /* initialize */
  /* allocate a back-end specific to this request */
  ngbe = (struct setnetgrent_backend *)malloc(sizeof(struct setnetgrent_backend));
  if (ngbe == NULL)
    return NSS_STATUS_UNAVAIL;
  ngbe->ops = netgroup_setnetgrent_ops;
  ngbe->n_ops = sizeof(netgroup_setnetgrent_ops) / sizeof(nss_backend_op_t);
  ngbe->fp = NULL;
  ngbe->seen_groups = set_new();
  ngbe->unseen_groups = set_new();
  /* start the first search */
  retv = start_netgroup_request(ngbe, SETNETGRENT_ARGS(args)->netgroup);
  if (retv != NSS_STATUS_SUCCESS)
  {
    netgroup_setnetgrent_destructor((nss_backend_t *)ngbe, args);
    return retv;
  }
  /* return the new back-end */
  SETNETGRENT_ARGS(args)->iterator = (nss_backend_t *)ngbe;
  return NSS_STATUS_SUCCESS;
}

static nss_backend_op_t netgroup_ops[] = {
  nss_ldap_destructor,
  NULL,
  NULL,
  NULL,
  NULL, /* TODO:_nss_ldap_netgr_in */
  netgroup_setnetgrent_constructor
};

nss_backend_t *_nss_ldap_netgroup_constr(const char UNUSED(*db_name),
                                         const char UNUSED(*src_name),
                                         const char UNUSED(*cfg_args))
{
  return nss_ldap_constructor(netgroup_ops, sizeof(netgroup_ops));
}

#endif /* NSS_FLAVOUR_SOLARIS */