n2n/src/n2n.c

/**
 * (C) 2007-20 - ntop.org and contributors
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not see see <http://www.gnu.org/licenses/>
 *
 */

#include "n2n.h"

#include "minilzo.h"

#include <assert.h>


static const uint8_t broadcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
static const uint8_t multicast_addr[6] = { 0x01, 0x00, 0x5E, 0x00, 0x00, 0x00 }; /* First 3 bytes are meaningful */
static const uint8_t ipv6_multicast_addr[6] = { 0x33, 0x33, 0x00, 0x00, 0x00, 0x00 }; /* First 2 bytes are meaningful */

/* ************************************** */

SOCKET open_socket(int local_port, int bind_any) {
  SOCKET sock_fd;
  struct sockaddr_in local_address;
  int sockopt;

  if((sock_fd = socket(PF_INET, SOCK_DGRAM, 0))  < 0) {
    traceEvent(TRACE_ERROR, "Unable to create socket [%s][%d]\n",
	       strerror(errno), sock_fd);
    return(-1);
  }

#ifndef WIN32
  /* fcntl(sock_fd, F_SETFL, O_NONBLOCK); */
#endif

  sockopt = 1;
  setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR, (char *)&sockopt, sizeof(sockopt));

  memset(&local_address, 0, sizeof(local_address));
  local_address.sin_family = AF_INET;
  local_address.sin_port = htons(local_port);
  local_address.sin_addr.s_addr = htonl(bind_any ? INADDR_ANY : INADDR_LOOPBACK);

  if(bind(sock_fd,(struct sockaddr*) &local_address, sizeof(local_address)) == -1) {
    traceEvent(TRACE_ERROR, "Bind error on local port %u [%s]\n", local_port, strerror(errno));
    return(-1);
  }

  return(sock_fd);
}

static int traceLevel = 2 /* NORMAL */;
static int useSyslog = 0, syslog_opened = 0;
static FILE *traceFile = NULL;

int getTraceLevel() {
  return(traceLevel);
}

void setTraceLevel(int level) {
  traceLevel = level;
}

void setUseSyslog(int use_syslog) {
  useSyslog= use_syslog;
}

void setTraceFile(FILE *f) {
  traceFile = f;
}

void closeTraceFile() {
  if (traceFile != NULL && traceFile != stdout) {
    fclose(traceFile);
  }
#ifndef WIN32
  if (useSyslog && syslog_opened) {
    closelog();
    syslog_opened = 0;
  }
#endif
}

#define N2N_TRACE_DATESIZE 32
void traceEvent(int eventTraceLevel, char* file, int line, char * format, ...) {
  va_list va_ap;

  if(traceFile == NULL)
    traceFile = stdout;

  if(eventTraceLevel <= traceLevel) {
    char buf[1024];
    char out_buf[1280];
    char theDate[N2N_TRACE_DATESIZE];
    char *extra_msg = "";
    time_t theTime = time(NULL);
    int i;

    /* We have two paths - one if we're logging, one if we aren't
     *   Note that the no-log case is those systems which don't support it(WIN32),
     *                                those without the headers !defined(USE_SYSLOG)
     *                                those where it's parametrically off...
     */

    memset(buf, 0, sizeof(buf));
    strftime(theDate, N2N_TRACE_DATESIZE, "%d/%b/%Y %H:%M:%S", localtime(&theTime));

    va_start(va_ap, format);
    vsnprintf(buf, sizeof(buf)-1, format, va_ap);
    va_end(va_ap);

    if(eventTraceLevel == 0 /* TRACE_ERROR */)
      extra_msg = "ERROR: ";
    else if(eventTraceLevel == 1 /* TRACE_WARNING */)
      extra_msg = "WARNING: ";

    while(buf[strlen(buf)-1] == '\n') buf[strlen(buf)-1] = '\0';

#ifndef WIN32
    if(useSyslog) {
      if(!syslog_opened) {
        openlog("n2n", LOG_PID, LOG_DAEMON);
        syslog_opened = 1;
      }

      snprintf(out_buf, sizeof(out_buf), "%s%s", extra_msg, buf);
      syslog(LOG_INFO, "%s", out_buf);
    } else {
		for(i=strlen(file)-1; i>0; i--) if(file[i] == '/') { i++; break; };
		snprintf(out_buf, sizeof(out_buf), "%s [%s:%d] %s%s", theDate, &file[i], line, extra_msg, buf);
      fprintf(traceFile, "%s\n", out_buf);
      fflush(traceFile);
    }
#else
    /* this is the WIN32 code */
    for(i=strlen(file)-1; i>0; i--) if(file[i] == '\\') { i++; break; };
    snprintf(out_buf, sizeof(out_buf), "%s [%s:%d] %s%s", theDate, &file[i], line, extra_msg, buf);
    fprintf(traceFile, "%s\n", out_buf);
    fflush(traceFile);
#endif
  }

}

/* *********************************************** */

/* addr should be in network order. Things are so much simpler that way. */
char* intoa(uint32_t /* host order */ addr, char* buf, uint16_t buf_len) {
  char *cp, *retStr;
  uint8_t byteval;
  int n;

  cp = &buf[buf_len];
  *--cp = '\0';

  n = 4;
  do {
    byteval = addr & 0xff;
    *--cp = byteval % 10 + '0';
    byteval /= 10;
    if(byteval > 0) {
      *--cp = byteval % 10 + '0';
      byteval /= 10;
      if(byteval > 0)
        *--cp = byteval + '0';
    }
    *--cp = '.';
    addr >>= 8;
  } while(--n > 0);

  /* Convert the string to lowercase */
  retStr =(char*)(cp+1);

  return(retStr);
}


/** Convert subnet prefix bit length to host order subnet mask. */
uint32_t bitlen2mask(uint8_t bitlen) {
	uint8_t i;
	uint32_t mask = 0;
	for (i = 1; i <= bitlen; ++i) {
		mask |= 1 << (32 - i);
	}
	return mask;
}


/** Convert host order subnet mask to subnet prefix bit length. */
uint8_t mask2bitlen(uint32_t mask) {
	uint8_t i, bitlen = 0;
	for (i = 0; i < 32; ++i) {
		if ((mask << i) & 0x80000000) ++bitlen;
		else break;
	}
	return bitlen;
}


/* *********************************************** */

char * macaddr_str(macstr_t buf,
		   const n2n_mac_t mac)
{
  snprintf(buf, N2N_MACSTR_SIZE, "%02X:%02X:%02X:%02X:%02X:%02X",
	   mac[0] & 0xFF, mac[1] & 0xFF, mac[2] & 0xFF,
	   mac[3] & 0xFF, mac[4] & 0xFF, mac[5] & 0xFF);
  return(buf);
}

/* *********************************************** */

uint8_t is_multi_broadcast(const uint8_t * dest_mac) {

  int is_broadcast =(memcmp(broadcast_addr, dest_mac, 6) == 0);
  int is_multicast =(memcmp(multicast_addr, dest_mac, 3) == 0);
  int is_ipv6_multicast =(memcmp(ipv6_multicast_addr, dest_mac, 2) == 0);

  return is_broadcast || is_multicast || is_ipv6_multicast;

}

/* http://www.faqs.org/rfcs/rfc908.html */


/* *********************************************** */

char* msg_type2str(uint16_t msg_type) {
  switch(msg_type) {
  case MSG_TYPE_REGISTER: return("MSG_TYPE_REGISTER");
  case MSG_TYPE_DEREGISTER: return("MSG_TYPE_DEREGISTER");
  case MSG_TYPE_PACKET: return("MSG_TYPE_PACKET");
  case MSG_TYPE_REGISTER_ACK: return("MSG_TYPE_REGISTER_ACK");
  case MSG_TYPE_REGISTER_SUPER: return("MSG_TYPE_REGISTER_SUPER");
  case MSG_TYPE_REGISTER_SUPER_ACK: return("MSG_TYPE_REGISTER_SUPER_ACK");
  case MSG_TYPE_REGISTER_SUPER_NAK: return("MSG_TYPE_REGISTER_SUPER_NAK");
  case MSG_TYPE_FEDERATION: return("MSG_TYPE_FEDERATION");
  default: return("???");
  }

  return("???");
}

/* *********************************************** */

void hexdump(const uint8_t *buf, size_t len) {
	size_t i;

	if (0 == len) { return; }

	printf("-----------------------------------------------\n");
	for (i = 0; i < len; i++) {
		if ((i > 0) && ((i % 16) == 0)) { printf("\n"); }
		printf("%02X ", buf[i] & 0xFF);
	}
	printf("\n");
	printf("-----------------------------------------------\n");
}


/* *********************************************** */

void print_n2n_version() {
  printf("Welcome to n2n v.%s for %s\n"
         "Built on %s\n"
	 "Copyright 2007-2020 - ntop.org and contributors\n\n",
         GIT_RELEASE, PACKAGE_OSNAME, PACKAGE_BUILDDATE);
}

/* *********************************************** */ 

size_t purge_expired_registrations(struct peer_info ** peer_list, time_t* p_last_purge) {
  time_t now = time(NULL);
  size_t num_reg = 0;

  if((now - (*p_last_purge)) < PURGE_REGISTRATION_FREQUENCY) return 0;

  traceEvent(TRACE_DEBUG, "Purging old registrations");

  num_reg = purge_peer_list(peer_list, now-REGISTRATION_TIMEOUT);

  (*p_last_purge) = now;
  traceEvent(TRACE_DEBUG, "Remove %ld registrations", num_reg);

  return num_reg;
}

/** Purge old items from the peer_list and return the number of items that were removed. */
size_t purge_peer_list(struct peer_info ** peer_list,
		       time_t purge_before)
{
  struct peer_info *scan, *tmp;
  size_t retval=0;

  HASH_ITER(hh, *peer_list, scan, tmp) {
    if(scan->last_seen < purge_before) {
      HASH_DEL(*peer_list, scan);
      retval++;
      free(scan);
    }
  }

  return retval;
}

/** Purge all items from the peer_list and return the number of items that were removed. */
size_t clear_peer_list(struct peer_info ** peer_list)
{
  struct peer_info *scan, *tmp;
  size_t retval=0;

  HASH_ITER(hh, *peer_list, scan, tmp) {
    HASH_DEL(*peer_list, scan);
    retval++;
    free(scan);
  }

  return retval;
}

static uint8_t hex2byte(const char * s)
{
  char tmp[3];
  tmp[0]=s[0];
  tmp[1]=s[1];
  tmp[2]=0; /* NULL term */

  return((uint8_t)strtol(tmp, NULL, 16));
}

extern int str2mac(uint8_t * outmac /* 6 bytes */, const char * s)
{
  size_t i;

  /* break it down as one case for the first "HH", the 5 x through loop for
   * each ":HH" where HH is a two hex nibbles in ASCII. */

  *outmac=hex2byte(s);
  ++outmac;
  s+=2; /* don't skip colon yet - helps generalise loop. */

  for(i=1; i<6; ++i)
    {
      s+=1;
      *outmac=hex2byte(s);
      ++outmac;
      s+=2;
    }

  return 0; /* ok */
}

extern char * sock_to_cstr(n2n_sock_str_t out,
			   const n2n_sock_t * sock) {
  if(NULL == out) { return NULL; }
  memset(out, 0, N2N_SOCKBUF_SIZE);

  if(AF_INET6 == sock->family) {
    /* INET6 not written yet */
    snprintf(out, N2N_SOCKBUF_SIZE, "XXXX:%hu", sock->port);
    return out;
  } else {
    const uint8_t * a = sock->addr.v4;

    snprintf(out, N2N_SOCKBUF_SIZE, "%hu.%hu.%hu.%hu:%hu", 
	     (unsigned short)(a[0] & 0xff),
	     (unsigned short)(a[1] & 0xff),
	     (unsigned short)(a[2] & 0xff),
	     (unsigned short)(a[3] & 0xff),
	     (unsigned short)sock->port);
    return out;
  }
}

char *ip_subnet_to_str(dec_ip_bit_str_t buf, const n2n_ip_subnet_t *ipaddr) {
	snprintf(buf, sizeof(dec_ip_bit_str_t), "%hhu.%hhu.%hhu.%hhu/%hhu",
	         (uint8_t) ((ipaddr->net_addr >> 24) & 0xFF),
	         (uint8_t) ((ipaddr->net_addr >> 16) & 0xFF),
	         (uint8_t) ((ipaddr->net_addr >> 8) & 0xFF),
	         (uint8_t) (ipaddr->net_addr & 0xFF),
	         ipaddr->net_bitlen);
	return buf;
}


/* @return 1 if the two sockets are equivalent. */
int sock_equal(const n2n_sock_t * a,
	       const n2n_sock_t * b) {
  if(a->port != b->port)     { return(0); }
  if(a->family != b->family) { return(0); }

  switch(a->family) {
  case AF_INET:
    if(memcmp(a->addr.v4, b->addr.v4, IPV4_SIZE))
      return(0);
    break;
  default:
    if(memcmp(a->addr.v6, b->addr.v6, IPV6_SIZE))
      return(0);
    break;
  }

  /* equal */
  return(1);
}

/* *********************************************** */

#if defined(WIN32)
int gettimeofday(struct timeval *tp, void *tzp) {
  time_t clock;
  struct tm tm;
  SYSTEMTIME wtm;
  GetLocalTime(&wtm);
  tm.tm_year = wtm.wYear - 1900;
  tm.tm_mon = wtm.wMonth - 1;
  tm.tm_mday = wtm.wDay;
  tm.tm_hour = wtm.wHour;
  tm.tm_min = wtm.wMinute;
  tm.tm_sec = wtm.wSecond;
  tm.tm_isdst = -1;
  clock = mktime(&tm);
  tp->tv_sec = clock;
  tp->tv_usec = wtm.wMilliseconds * 1000;
  return (0);
}
#endif


// returns a time stamp for use with replay protection
uint64_t time_stamp (void) {

  struct timeval tod;
  uint64_t micro_seconds;

  gettimeofday (&tod, NULL);
  /* We will (roughly) calculate the microseconds since 1970 leftbound into the return value.
     The leading 32 bits are used for tv_sec. The following 20 bits (sufficent as microseconds
     fraction never exceeds 1,000,000,) encode the value tv_usec. The remaining lowest 12 bits
     are kept random for use in IV */
  micro_seconds = n2n_rand();
  micro_seconds = ( (((uint64_t)(tod.tv_sec) << 32) + (tod.tv_usec << 12))
                  |  (micro_seconds >> 52) );
  // more exact but more costly due to the multiplication:
  // micro_seconds = (tod.tv_sec * 1000000 + tod.tv_usec) << 12) | ...

  return (micro_seconds);
}


// returns an initial time stamp for use with replay protection
uint64_t initial_time_stamp (void) {

  return ( time_stamp() - TIME_STAMP_FRAME );
}


// checks if a provided time stamp is consistent with current time and previously valid time stamps
// and, in case of validity, updates the "last valid time stamp"
int time_stamp_verify_and_update (uint64_t stamp, uint64_t * previous_stamp) {

  int64_t diff; // do not change to unsigned

  // is it around current time (+/- allowed deviation TIME_STAMP_FRAME)?
  diff = stamp - time_stamp();
  // abs()
  diff = (diff < 0 ? -diff : diff);
  if(diff >= TIME_STAMP_FRAME) {
      traceEvent(TRACE_DEBUG, "time_stamp_verify_and_update found a timestamp out of allowed frame.");
      return (0); // failure
  }

  // if applicable: is it higher than previous time stamp (including allowed deviation of TIME_STAMP_JITTER)?
  if(NULL != previous_stamp) {
    // if no jitter allowed, reset lowest three (random) nybbles; the codnition shoudl already be evaluated by the compiler
    if(TIME_STAMP_JITTER == 0) {
      stamp = (stamp >> 12) << 12;
      *previous_stamp = (*previous_stamp >> 12) << 12;
    }
    diff = stamp - *previous_stamp + TIME_STAMP_JITTER;
    if(diff <= 0) {
      traceEvent(TRACE_DEBUG, "time_stamp_verify_and_update found a timestamp too old compared to previous.");
      return (0); // failure
    }
    // for not allowing to exploit the allowed TIME_STAMP_JITTER to "turn the clock backwards",
    // set the higher of the values
    *previous_stamp = (stamp > *previous_stamp ? stamp : *previous_stamp);
  }

  return (1); // success
}