/***********************************************************/
/* Functions that uses the system devices to determine the */
/* MTU value from a network, the loopback device, the IP   */
/* address from an outgoing interface, etc.                */
/***********************************************************/
/* To solve:                                               */
/* - Under Solaris 2.5.1 it's not possible to get the      */
/*   outgoing interface without reading the routing table, */
/*   get the interface name and get the netmask from       */
/*   /etc/netmasks. This implies (among other things) the  */
/*   use of STREAMS with the /dev/ip device ...            */
/*   Maybe some day ;)                                     */
/***********************************************************/
#ifndef lint
static const char rcsid[] = 
       "$Id: device.c,v 1.3 2001/04/16 15:47:00 slay Exp $";
#endif

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>

#ifdef HAVE_SYS_SOCKIO_H
#include <sys/sockio.h>
#endif

#include <sys/ioctl.h>

#ifdef HAVE_NET_IF_H
#include <net/if.h>
#endif

#include <netdb.h>

#ifdef HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif

#ifdef HAVE_NETINET_IN_SYSTM_H
#include <netinet/in_systm.h>
#else
#ifdef HAVE_NETINET_IN_SYSTEM_H
#include <netinet/in_system.h>
#endif
#endif

#include <netinet/in.h>

#ifdef HAVE_STRING_H
#include <string.h>
#endif

#ifdef HAVE_STRINGS_H
#include <strings.h>
#endif

#ifdef HAVE_BSTRING_H
#include <bstring.h>
#endif

#include <stdarg.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include "device.h"


/***************************************************/
/* Try to get the mtu, name and IP address of the  */
/* outgoing interface.                             */
/* First: Try it using the "Stevens way".          */
/* Next: Try it fetching the hostname of the host, */
/*       then his IP address and then the network  */
/*       device.                                   */
/* Next: Trying to fetch the first non loopback    */
/*       network device.                           */
/***************************************************/
/* No value return.                                */
/***************************************************/
void 
where2route( struct sockaddr_in *destination )
{
  struct hostent *thishost = NULL;
  char thisname[MAXHOSTNAMELEN+1];
  struct sockaddr_in *aux;
  
  if ( get_iface_out( destination, (struct sockaddr_in *)&packet.iface2route.ip ) )
  {
     thishost = gethostbyname(thisname);
     if ( !thishost || gethostname(thisname, MAXHOSTNAMELEN) )
     {
        if (!first_nonloopback((struct mi_ifaz *)&packet.iface2route) )
           go_out(1, "Unable to select an interface to route throughout");
     }
     else
     {
        aux = (struct sockaddr_in *)&packet.iface2route.ip;
        copymem( thishost->h_addr_list[0], (char *)&aux->sin_addr.s_addr, sizeof(struct in_addr) );
        if ( !look4dev((struct mi_ifaz *)&packet.iface2route) )
        {
           if (!first_nonloopback((struct mi_ifaz *)&packet.iface2route) )
              go_out(1,"Unable to select an interface to route throughout");
        }
     }
     return;
  }

  if ( !look4dev((struct mi_ifaz *)&packet.iface2route) )
  {
     if (!first_nonloopback((struct mi_ifaz *)&packet.iface2route) )
        go_out(1,"Unable to select an interface to route throughout");
  }
}


/**********************************/
/* Try to get the IP address from */
/* the outgoing interface "ala"   */
/* Stevens way. ;)                */
/**********************************/
/* Return 1 on error, 0 else other*/
/**********************************/
int 
get_iface_out( struct sockaddr_in *ip2see, struct sockaddr_in *aux )
{
  int sock_rt, len, on=1;
  struct sockaddr_in iface_out;
 
  initmem( (char *)&iface_out, sizeof(struct sockaddr_in));
  
  sock_rt = socket(AF_INET, SOCK_DGRAM, 0 );

  ip2see->sin_port = htons(26731);
  
  if ( setsockopt( sock_rt, SOL_SOCKET, SO_BROADCAST, (char *)&on, sizeof(on) )
       == -1 )
  { 
#ifdef DEBUG
        fprintf(stderr, "setsockopt -> %s\n", sys_errlist[errno] );
#endif
     close(sock_rt);
     return 1;
  }
  
  if (connect(sock_rt, (struct sockaddr *)ip2see, sizeof(struct sockaddr_in) )
       == -1 )
  {
#ifdef DEBUG
        fprintf(stderr,"connect -> %s\n", sys_errlist[errno] );
#endif
     close(sock_rt);
     return 1;
  }

  len = sizeof(iface_out);
  if ( getsockname( sock_rt, (struct sockaddr *)&iface_out, &len ) == -1 )
  {
#ifdef DEBUG
        fprintf(stderr,"getsockname -> %s\n", sys_errlist[errno] );
#endif
     close(sock_rt);
     return 1;
  }
  
  close(sock_rt);

  if ( !iface_out.sin_addr.s_addr )
     return 1;
  
  copymem( (char *)&iface_out, (char *)aux, sizeof(struct sockaddr_in));
  return 0; 
}


/*******************************************/
/* Copy the values from the interface      */
/* "nombre" to "mi_interfaz" struct        */
/*******************************************/
/* Arguments :                             */
/*   - sock_disp : Socket RAW descriptor   */
/*                 with the kernel.        */
/*   - nombre : Interface name.            */
/*   - mi_interfaz : Struct where to put   */
/*                   the interface values. */
/*******************************************/
/* Return : 1 on error, or 0 else other.   */
/*******************************************/
int 
put_interface( int sock_disp, char *nombre, struct mi_ifaz *mi_interfaz )
{
  struct ifreq if_aux; /* Estructura "auxiliar" :) */

  strncpy(if_aux.ifr_name, nombre, sizeof(if_aux.ifr_name));
  
  if (ioctl( sock_disp, SIOCGIFADDR, &if_aux) < 0)
  {
     if ( errno == EADDRNOTAVAIL || errno == EAFNOSUPPORT)
        return 1;
#ifdef DEBUG
        fprintf(stderr,"SIOCGIFADDR -> %s\n", sys_errlist[errno]);
#endif
     return 1;
  }

  mi_interfaz->ip = if_aux.ifr_addr;

  strncpy(if_aux.ifr_name, nombre, sizeof(if_aux.ifr_name));

  if (ioctl(sock_disp, SIOCGIFMTU, &if_aux) < 0)
  {
#ifdef DEBUG
     fprintf(stderr,"SIOCGIFMTU (%s) -> %s\n", mi_interfaz->name,
                 sys_errlist[errno]);
#endif
     return 1;
  }

#ifdef SOLARIS
  mi_interfaz->mtu = if_aux.ifr_metric;
#else
  mi_interfaz->mtu = if_aux.ifr_mtu;
#endif

  strncpy(if_aux.ifr_name, nombre, sizeof(if_aux.ifr_name));

  if ( ioctl( sock_disp, SIOCGIFFLAGS, &if_aux ) < 0 )
  {
#ifdef DEBUG
     fprintf(stderr,"SIOCGIFFLAGS (%s) -> %s\n", mi_interfaz->name,
             sys_errlist[errno]);
#endif
     return 1;
  }
  mi_interfaz->flags = if_aux.ifr_flags;
 
  return 0;
}


/*********************************************/
/* Look for a device on the device table by  */
/* interface name or by IP address.          */
/* If 'iface2search->name[0]' != NULL        */
/* then we search by name.                   */
/* If 'iface2search->name[0]' == NULL        */
/* then we search by IP address.             */
/*********************************************/
/* Return 1 on exit and put the interface IP */
/* address, mtu and flags on 'iface2search'. */
/* Return 0 on error.                        */
/*********************************************/
int 
look4dev( struct mi_ifaz *iface2search )
{
  struct ifconf ifc;
  struct ifreq *iface;
  struct mi_ifaz mi_interfaz;
  struct sockaddr_in *aux_in;
  struct sockaddr_in *aux_in2=NULL;
  char buffer[MAX_IFCONF*32];
  int i, sock_disp;
  
  if ( (sock_disp = socket(AF_INET, SOCK_DGRAM, 0) ) < 0)
  {
     fprintf(stderr, "socket -> %s\n", sys_errlist[errno]);
     return 1;
  }
  
  ifc.ifc_len = sizeof(buffer);
  ifc.ifc_buf = buffer;
  if (ioctl( sock_disp, SIOCGIFCONF, &ifc) < 0)
  {
     fprintf(stderr, "SIOCGIFCONF -> %s\n", sys_errlist[errno]);
     close(sock_disp);
     return 1;
  }

  iface = ifc.ifc_req;

  for ( i=0; i < ifc.ifc_len; 
        iface = (struct ifreq *)((char *)ifc.ifc_req + i ) )
  {

#ifdef HAVE_SOCKADDR_SA_LEN  
     i+= MAX(sizeof(struct sockaddr),iface->ifr_addr.sa_len) +
         sizeof(iface->ifr_name);
#else
     i+= sizeof(struct sockaddr) + sizeof(iface->ifr_name);
#endif

     if (!*(iface->ifr_name))
        continue;
        
     strncpy(mi_interfaz.name, iface->ifr_name, sizeof(mi_interfaz.name));

     if ( put_interface( sock_disp, iface->ifr_name, &mi_interfaz ) )
         continue;

     if ( mi_interfaz.flags & IFF_UP )
     {  
        if ( iface2search->name[0] ) /* Search by name...*/
        {
           if ( !strcmp(mi_interfaz.name, iface2search->name) )
           {
              copymem((char *)&mi_interfaz, (char *)iface2search, sizeof(struct mi_ifaz) );
              close(sock_disp);
              return 1;           }
        }
        else /* Search by IP address...*/
        {
           aux_in = (struct sockaddr_in *)&mi_interfaz.ip;
          aux_in2 = (struct sockaddr_in *)&(iface2search->ip);
           
           if ( aux_in2->sin_addr.s_addr == aux_in->sin_addr.s_addr )       
           {
              copymem((char *)&mi_interfaz, (char *)iface2search, sizeof(struct mi_ifaz) );
              close(sock_disp);
              return 1;
           }
        }
     }
  }
  close(sock_disp);

  return 0;
}


/*********************************************/
/* Look for the first non loopback device.   */
/*********************************************/
/* Return 1 on exit and put the interface IP */
/* address, mtu and flags on 'iface2search'  */
/* Return 0 on error.                        */
/*********************************************/
int 
first_nonloopback( struct mi_ifaz *iface2search )
{
  struct ifconf ifc;
  struct ifreq *iface;
  struct mi_ifaz mi_interfaz;
  char buffer[MAX_IFCONF*32];
  int i, sock_disp;
  
  if ( (sock_disp = socket(AF_INET, SOCK_DGRAM, 0) ) < 0)
  {
     fprintf(stderr, "socket -> %s\n", sys_errlist[errno]);
     return 1;
  }
  
  ifc.ifc_len = sizeof(buffer);
  ifc.ifc_buf = buffer;
  if (ioctl( sock_disp, SIOCGIFCONF, &ifc) < 0)
  {
     fprintf(stderr, "SIOCGIFCONF -> %s\n", sys_errlist[errno]);
     close(sock_disp);
     return 1;
  }

  iface = ifc.ifc_req;

  for ( i=0; i < ifc.ifc_len; 
        iface = (struct ifreq *)((char *)ifc.ifc_req + i ) )
  {
#ifdef HAVE_SOCKADDR_SA_LEN  
     i+= MAX(sizeof(struct sockaddr),iface->ifr_addr.sa_len) +
         sizeof(iface->ifr_name);
#else
     i+= sizeof(struct sockaddr) + sizeof(iface->ifr_name);
#endif

     if (!*(iface->ifr_name))
        continue;

     strncpy(mi_interfaz.name, iface->ifr_name, sizeof(mi_interfaz.name));

     if ( put_interface( sock_disp, iface->ifr_name, &mi_interfaz ) )
         continue;

     if ( ( mi_interfaz.flags & IFF_UP ) &&
          !( mi_interfaz.flags & IFF_LOOPBACK)
        )
     {  
        copymem((char *)&mi_interfaz, (char *)iface2search, sizeof(struct mi_ifaz) );
        close(sock_disp);
        return 1;
     }
  }
  close(sock_disp);
  return 0;
}