/* pi-csd.c: Connection Service Daemon, required for accepting logons via NetSync(tm)
 *
 * Copyright (c) 1997, Kenneth Albanowski
 *
 * This is free software, licensed under the GNU Public License V2.
 * See the file COPYING for details.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "pi-source.h"
#include "pi-socket.h"
#include "pi-dlp.h"
#include "pi-serial.h"
#include "pi-slp.h"
#include <signal.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <net/if.h>
#include <arpa/inet.h>
#include <netdb.h>

char hostname[130];
struct in_addr address, netmask;

void Help(char *argv[])
{
  fprintf(stderr,"usage:%s [options]\n",argv[0]);
  fprintf(stderr,"\n      <-h hostname> Name of host, used for verification");
  if (strlen(hostname))
  fprintf(stderr,"\n                   (defaults to '%s')", hostname);
  else
  fprintf(stderr,"\n                   (no default)");  
  fprintf(stderr,"\n      <-a address> IP address of host");
  if (address.s_addr)
  fprintf(stderr,"\n                   (defaults to '%s')", inet_ntoa(address));
  else
  fprintf(stderr,"\n                   (no default)");  
  fprintf(stderr,"\n      <-s address> Subnet mask of IP address");
  if (netmask.s_addr)
  fprintf(stderr,"\n                   (defaults to '%s')", inet_ntoa(netmask));
  else
  fprintf(stderr,"\n                   (no default)");  
  fprintf(stderr,"\n      <-q> Quiet: turn off status messages\n");
  fprintf(stderr,"\nNote: Currently the subnet mask is not used by %s.\n", argv[0]);
  exit(0);
}

#ifdef HAVE_SA_LEN
#ifndef max
#define max(a,b) ((a) > (b) ? (a) : (b))
#endif
#define ifreq_size(i) max(sizeof(struct ifreq),\
     sizeof((i).ifr_name)+(i).ifr_addr.sa_len)
#else
#define ifreq_size(i) sizeof(struct ifreq)
#endif /* HAVE_SA_LEN*/


/* What, me worry? */     
#ifndef IFF_POINTOPOINT
# ifdef IFF_POINTTOPOINT
#  define IFF_POINTOPOINT IFF_POINTTOPOINT
# endif
#endif


/* While this function is useful in pi-csd, it is intended also to
   be a demonstration of the proper (or improper, if I'm unlucky) techniques
   to retrieve networking information.*/
   
void fetch_host(char * hostname, int hostlen, struct in_addr *address, struct in_addr * mask)
{
  int s, n, i;
  struct ifconf ifc;
  struct ifreq * ifr, ifreqaddr, ifreqmask;
  struct hostent * hent;
  
#ifdef HAVE_GETHOSTNAME
  /* Get host name the easy way */
  
  gethostname(hostname, hostlen);
#else
# ifdef HAVE_UNAME
  struct utsname uts;
  
  if (uname(&uts)==0) {
    strncpy(hostname, uts.nodename, hostlen-1);
    hostname[hostlen-1] = '\0';
  }
# endif /*def HAVE_UNAME*/
#endif /*def HAVE_GETHOSTNAME*/

  /* Get host address through DNS */
  hent = gethostbyname(hostname);
  
  if (hent) {
    while(*hent->h_addr_list) {
      struct in_addr haddr;
      memcpy(&haddr, *(hent->h_addr_list++), sizeof(haddr));
      if (haddr.s_addr != inet_addr("127.0.0.1"))
      	memcpy(address, &haddr, sizeof(haddr));
    }
  }

#if defined(SIOCGIFCONF) && defined(SIOCGIFFLAGS) 
  s = socket(AF_INET, SOCK_DGRAM, 0);

  if (s<0)
    return;
    
  ifc.ifc_buf = calloc(1024, 1);
  ifc.ifc_len = 1024;
  
  if (ioctl(s, SIOCGIFCONF, (char*)&ifc)<0)
    goto done;
  
  n = ifc.ifc_len;
  for (i=0; i<n; i+=ifreq_size(*ifr)) {
    struct sockaddr_in * a;
    struct sockaddr_in * b;
    ifr = (struct ifreq*)((caddr_t) ifc.ifc_buf+i);
    a = (struct sockaddr_in*)&ifr->ifr_addr;
    strncpy(ifreqaddr.ifr_name, ifr->ifr_name, sizeof(ifreqaddr.ifr_name));
    strncpy(ifreqmask.ifr_name, ifr->ifr_name, sizeof(ifreqmask.ifr_name));
    
    if (ioctl(s, SIOCGIFFLAGS, (char *)&ifreqaddr) < 0)
      continue;

    /* Reject loopback device */
#ifdef IFF_LOOPBACK
    if (ifreqaddr.ifr_flags & IFF_LOOPBACK)
      continue;
#endif /*def IFF_LOOPBACK*/

#ifdef IFF_UP
    /* Reject down devices */
    if (!(ifreqaddr.ifr_flags & IFF_UP))
      continue;
#endif /*def IFF_UP*/
      
    if (ifr->ifr_addr.sa_family != AF_INET)
      continue;

    /* If it is a point-to-point device, use the dest address */
#if defined(IFF_POINTOPOINT) && defined(SIOCGIFDSTADDR)
    if (ifreqaddr.ifr_flags & IFF_POINTOPOINT) {
      if (ioctl(s, SIOCGIFDSTADDR, (char *)&ifreqaddr) < 0)
        break;

      a = (struct sockaddr_in*)&ifreqaddr.ifr_dstaddr;
    
      if (address->s_addr == 0) {
        memcpy(address, &a->sin_addr, sizeof(struct in_addr));
      }
    } else
#endif /*defined(IFF_POINTOPOINT) && defined(SIOCGIFDSTADDR)*/
    /* If it isn't a point-to-point device, use the address */
#ifdef SIOCGIFADDR
    {
      if (ioctl(s, SIOCGIFADDR, (char *)&ifreqaddr) < 0)
        break;

      a = (struct sockaddr_in*)&ifreqaddr.ifr_addr;

      if (address->s_addr == 0) {
        memcpy(address, &a->sin_addr, sizeof(struct in_addr));
      }
    }
#endif /*def SIOCGIFADDR*/    
    /* OK, we've got an address */

    /* Compare netmask against the current address and see if it seems to match. */
#ifdef SIOCGIFNETMASK    
    if (ioctl(s, SIOCGIFNETMASK, (char *)&ifreqmask) < 0)
      break;

/*
 * Is there any system where we need to use ifr_netmask?
 */
#if 1
    b = (struct sockaddr_in*)&ifreqmask.ifr_addr;
#else
    b = (struct sockaddr_in*)&ifreqmask.ifr_netmask;
#endif

    if ((mask->s_addr == 0) && (address->s_addr != 0)) {
      if ((b->sin_addr.s_addr & a->sin_addr.s_addr) == (b->sin_addr.s_addr & address->s_addr)) {
        memcpy(mask, &b->sin_addr, sizeof(struct in_addr));
        
        /* OK, we've got a netmask */
        
        break;
      }
    }
#endif /*def SIOCGIFNETMASK*/

  }
  
done:
  free(ifc.ifc_buf);
  close(s);
#endif /*defined(SIOCGIFCONF) && defined(SIOCGIFFLAGS)*/
}

void main(int argc, char*argv[]) {
	int sockfd;
	struct sockaddr_in serv_addr, cli_addr;
	int clilen;
	char mesg[1026];
	fd_set rset;
	int n;
	struct in_addr raddress;

  char * progname;
  extern char* optarg;
  extern int optind;

  struct hostent * hent;
  int quiet=0;
  
  progname = argv[0];

  memset(&address, 0, sizeof(address));
  memset(&netmask, 0, sizeof(netmask));
  hostname[0] = 0;
  
  fetch_host(hostname, 128, &address, &netmask);
  
  while ((n = getopt(argc, argv, "h:s:a:q")) != EOF) {
    switch (n) {
      case 'h':
        strcpy(hostname, optarg);
        break;
      case 'a':
        if (!inet_aton(optarg, &address))
          if ((hent = gethostbyname(optarg)))
  	    memcpy(&address.s_addr, hent->h_addr, sizeof(address));
  	  else {
  	    fprintf(stderr, "Invalid address '%s'\n\n", optarg);
  	    Help(argv);
  	  }
        break;
      case 's':
        if (!inet_aton(optarg, &netmask))
          Help(argv);
        break;
      case 'q':
        quiet = 1;
        break;
      case 'H': case '?': default:
        Help(argv);
    }
  }
  
  if ((address.s_addr == 0) || (strlen(hostname)==0))
    Help(argv); /* cannot execute without address and hostname */
	
  sockfd = socket(AF_INET, SOCK_DGRAM, 0);
  if (sockfd <0 ) {
    perror("Unable to get socket");
    exit(1);
  }

  memset(&serv_addr, 0, sizeof(serv_addr));
  serv_addr.sin_family = AF_INET;
  serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
  serv_addr.sin_port = htons(14237);

  if (bind(sockfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr))< 0) {
    perror("Unable to bind socket");
    exit(1);
  }
  
  if (!quiet) {
    fprintf(stderr, "%s(%d): Connection Service Daemon for PalmPilot(tm) active.\n",
                progname, getpid());
    fprintf(stderr, "%s(%d): Accepting connection requests for '%s' at %s",
            progname, getpid(),
            hostname,
            inet_ntoa(address)
           );
    fprintf(stderr, " with mask %s.\n",
            inet_ntoa(netmask)
           );
  }
  for (;;) {
    clilen = sizeof(cli_addr);
    FD_ZERO(&rset);
    FD_SET(sockfd, &rset);
    if (select(sockfd+1, &rset, 0, 0, 0)<0) {
      perror("select failure");
      exit(1);
    }
    n = recvfrom(sockfd, mesg, 1024, 0, (struct sockaddr*)&cli_addr, &clilen);

    if (n<0) {
      continue;
    }

    mesg[n] = 0;

    if (!quiet) {
      hent = gethostbyaddr((char*)&cli_addr.sin_addr.s_addr,4,AF_INET);
      memcpy(&raddress, &cli_addr.sin_addr.s_addr, 4);

      fprintf(stderr, "%s(%d): Connection from %s[%s], ",
              progname,
              getpid(),
              hent ? hent->h_name : "", 
              inet_ntoa(raddress));
    }

    if (get_short(mesg) != 0xFADE)
      goto invalid;

    if ((get_byte(mesg+2) == 0x01) && (n>12)) {
      struct in_addr ip, mask;
      char * name = mesg+12;
      memcpy(&ip, mesg+4, 4);
      memcpy(&mask, mesg+8, 4);

      if (!quiet) {
        fprintf(stderr, "req '%s', %s",
                name, inet_ntoa(ip));
                fprintf(stderr, ", %s", inet_ntoa(mask));
      }

      if (strcmp(hostname, name)==0) {
        if (!quiet)
          fprintf(stderr, " = accept.\n");

        set_byte(mesg+2, 0x02);
        memcpy(mesg+4, &address, 4); /* address is already in motorola byte order */
        n = sendto(sockfd, mesg, n, 0, (struct sockaddr*)&cli_addr, clilen);
        if (n < 0) {
          perror("sendto error");
        }
        continue;
      }
      if (!quiet)
        fprintf(stderr, " = reject.\n");
      continue;
    }

    invalid:
    if (!quiet)
      fprintf(stderr, "invalid packet of %d bytes:\n", n);
    dumpdata(mesg, n);
  }
}