/*
   common.c - common server code routines
   This file is part of the nss-pam-ldapd library.

   Copyright (C) 2006 West Consulting
   Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Arthur de Jong

   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 <stdio.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <strings.h>
#include <limits.h>
#include <netdb.h>
#include <string.h>
#include <regex.h>
#include <stdlib.h>

#include "nslcd.h"
#include "common.h"
#include "log.h"
#include "attmap.h"
#include "cfg.h"

/* simple wrapper around snptintf() to return non-0 in case
   of any failure (but always keep string 0-terminated) */
int mysnprintf(char *buffer,size_t buflen,const char *format, ...)
{
  int res;
  va_list ap;
  /* do snprintf */
  va_start(ap,format);
  res=vsnprintf(buffer,buflen,format,ap);
  va_end(ap);
  /* NULL-terminate the string just to be on the safe side */
  buffer[buflen-1]='\0';
  /* check if the string was completely written */
  return ((res<0)||(((size_t)res)>=buflen));
}

/* return the fully qualified domain name of the current host */
const char *getfqdn(void)
{
  static char *fqdn=NULL;
  char hostname[HOST_NAME_MAX+1];
  int hostnamelen;
  int i;
  struct hostent *host=NULL;
  /* if we already have a fqdn return that */
  if (fqdn!=NULL)
    return fqdn;
  /* get system hostname */
  if (gethostname(hostname,sizeof(hostname))<0)
  {
    log_log(LOG_ERR,"gethostname() failed: %s",strerror(errno));
    return NULL;
  }
  hostnamelen=strlen(hostname);
  /* lookup hostent */
  host=gethostbyname(hostname);
  if (host==NULL)
  {
    log_log(LOG_ERR,"gethostbyname(%s): %s",hostname,hstrerror(h_errno));
    /* fall back to hostname */
    fqdn=strdup(hostname);
    return fqdn;
  }
  /* check h_name for fqdn starting with our hostname */
  if ((strncasecmp(hostname,host->h_name,hostnamelen)==0)&&
      (host->h_name[hostnamelen]=='.')&&
      (host->h_name[hostnamelen+1]!='\0'))
  {
    fqdn=strdup(host->h_name);
    return fqdn;
  }
  /* also check h_aliases */
  for (i=0;host->h_aliases[i]!=NULL;i++)
  {
    if ((strncasecmp(hostname,host->h_aliases[i],hostnamelen)==0)&&
        (host->h_aliases[i][hostnamelen]=='.')&&
        (host->h_aliases[i][hostnamelen+1]!='\0'))
    {
      fqdn=strdup(host->h_aliases[i]);
      return fqdn;
    }
  }
  /* fall back to h_name if it has a dot in it */
  if (strchr(host->h_name,'.')!=NULL)
  {
    fqdn=strdup(host->h_name);
    return fqdn;
  }
  /* also check h_aliases */
  for (i=0;host->h_aliases[i]!=NULL;i++)
  {
    if (strchr(host->h_aliases[i],'.')!=NULL)
    {
      fqdn=strdup(host->h_aliases[i]);
      return fqdn;
    }
  }
  /* nothing found, fall back to hostname */
  fqdn=strdup(hostname);
  return fqdn;
}

const char *get_userpassword(MYLDAP_ENTRY *entry,const char *attr,char *buffer,size_t buflen)
{
  const char *tmpvalue;
  /* get the value */
  tmpvalue=attmap_get_value(entry,attr,buffer,buflen);
  if (tmpvalue==NULL)
    return NULL;
  /* go over the entries and return the remainder of the value if it
     starts with {crypt} or crypt$ */
  if (strncasecmp(tmpvalue,"{crypt}",7)==0)
    return tmpvalue+7;
  if (strncasecmp(tmpvalue,"crypt$",6)==0)
    return tmpvalue+6;
  /* just return the first value completely */
  return tmpvalue;
  /* TODO: support more password formats e.g. SMD5
    (which is $1$ but in a different format)
    (any code for this is more than welcome) */
}

/* Checks if the specified name seems to be a valid user or group name. */
int isvalidname(const char *name)
{
  return regexec(&nslcd_cfg->validnames,name,0,NULL,0)==0;
}

/* this writes a single address to the stream */
int write_address(TFILE *fp,MYLDAP_ENTRY *entry,const char *attr,
                  const char *addr)
{
  int32_t tmpint32;
  struct in_addr ipv4addr;
  struct in6_addr ipv6addr;
  /* try to parse the address as IPv4 first, fall back to IPv6 */
  if (inet_pton(AF_INET,addr,&ipv4addr)>0)
  {
    /* write address type */
    WRITE_INT32(fp,AF_INET);
    /* write the address length */
    WRITE_INT32(fp,sizeof(struct in_addr));
    /* write the address itself (in network byte order) */
    WRITE_TYPE(fp,ipv4addr,struct in_addr);
  }
  else if (inet_pton(AF_INET6,addr,&ipv6addr)>0)
  {
    /* write address type */
    WRITE_INT32(fp,AF_INET6);
    /* write the address length */
    WRITE_INT32(fp,sizeof(struct in6_addr));
    /* write the address itself (in network byte order) */
    WRITE_TYPE(fp,ipv6addr,struct in6_addr);
  }
  else
  {
    /* failure, log but write simple invalid address
       (otherwise the address list is messed up) */
    /* TODO: have error message in correct format */
    log_log(LOG_WARNING,"%s: %s: \"%s\" unparseble",
                        myldap_get_dn(entry),attmap_ether_cn,addr);
    /* write an illegal address type */
    WRITE_INT32(fp,-1);
    /* write an emtpy address */
    WRITE_INT32(fp,0);
  }
  /* we're done */
  return 0;
}

int read_address(TFILE *fp,char *addr,int *addrlen,int *af)
{
  int32_t tmpint32;
  int len;
  /* read address family */
  READ_INT32(fp,*af);
  if ((*af!=AF_INET)&&(*af!=AF_INET6))
  {
    log_log(LOG_WARNING,"incorrect address family specified: %d",*af);
    return -1;
  }
  /* read address length */
  READ_INT32(fp,len);
  if ((len>*addrlen)||(len<=0))
  {
    log_log(LOG_WARNING,"address length incorrect: %d",len);
    return -1;
  }
  *addrlen=len;
  /* read address */
  READ(fp,addr,len);
  /* we're done */
  return 0;
}

/* convert the provided string representation of a sid
   (e.g. S-1-5-21-1936905831-823966427-12391542-23578)
   to a format that can be used to search the objectSid property with */
char *sid2search(const char *sid)
{
  const char *tmpsid=sid;
  char *res,*tmp;
  int i=0;
  long int l;
  /* check the beginning of the string */
  if (strncasecmp(sid,"S-",2)!=0)
  {
    log_log(LOG_ERR,"error in SID %s",sid);
    exit(EXIT_FAILURE);
  }
  /* count the number of dashes in the sid */
  while (tmpsid!=NULL)
  {
    i++;
    tmpsid=strchr(tmpsid+1,'-');
  }
  i-=2; /* number of security ids plus one because we add the uid later */
  /* allocate memory */
  res=malloc(3+3+6*3+i*4*3+1);
  if (res==NULL)
  {
    log_log(LOG_CRIT,"malloc() failed to allocate memory");
    exit(1);
  }
  /* build the first part */
  l=strtol(sid+2,&tmp,10);
  sprintf(res,"\\%02x\\%02x",(int)l&0xff,(int)i);
  /* build authority part (we only handle 32 of the 48 bits) */
  l=strtol(tmp+1,&tmp,10);
  sprintf(res+strlen(res),"\\00\\00\\%02x\\%02x\\%02x\\%02x",
          (int)((l>>24)&0xff),(int)((l>>16)&0xff),(int)((l>>8)&0xff),(int)(l&0xff));
  /* go over the rest of the bits */
  while (*tmp!='\0')
  {
    l=strtol(tmp+1,&tmp,10);
    sprintf(res+strlen(res),"\\%02x\\%02x\\%02x\\%02x",
            (int)(l&0xff),(int)((l>>8)&0xff),(int)((l>>16)&0xff),(int)((l>>24)&0xff));
  }
  return res;
}

/* return the last security identifier of the binary sid */
long int binsid2id(const char *binsid)
{
  int i;
  /* find the position of the last security id */
  i=2+6+((((int)binsid[1])&0xff)-1)*4;
  return (((long int)binsid[i])&0xff)|((((long int)binsid[i+1])&0xff)<<8)|
         ((((long int)binsid[i+2])&0xff)<<16)|((((long int)binsid[i+3])&0xff)<<24);
}

#ifdef WANT_STRTOUI
/* provide a strtoui() implementation, similar to strtoul() but returning
   an range-checked unsigned int instead */
unsigned int strtoui(const char *nptr,char **endptr,int base)
{
  unsigned long val;
  val=strtoul(nptr,endptr,base);
  if (val>UINT_MAX)
  {
    errno=ERANGE;
    return UINT_MAX;
  }
  /* If errno was set by strtoul, we'll pass it back as-is */
  return (unsigned int)val;
}
#endif /* WANT_STRTOUI */