path: root/src/hello/hello.c

/*
     This file is part of GNUnet.
     Copyright (C) 2009, 2015 GNUnet e.V.

     GNUnet 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, or (at your
     option) any later version.

     GNUnet 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 GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     Boston, MA 02110-1301, USA.
*/

/**
 * @file hello/hello.c
 * @brief helper library for handling HELLOs
 * @author Christian Grothoff
 * @author Matthias Wachs
 */
#include "platform.h"
#include "gnunet_hello_lib.h"
#include "gnunet_protocols.h"
#include "gnunet_util_lib.h"
#include "gnunet_transport_plugin.h"

GNUNET_NETWORK_STRUCT_BEGIN

/**
 * A HELLO message is used to exchange information about
 * transports with other peers.  This struct is always
 * followed by the actual network addresses which have
 * the format:
 *
 * 1) transport-name (0-terminated)
 * 2) address-length (uint16_t, network byte order; possibly
 *    unaligned!)
 * 3) address expiration (`struct GNUNET_TIME_AbsoluteNBO`); possibly
 *    unaligned!)
 * 4) address (address-length bytes; possibly unaligned!)
 */
struct GNUNET_HELLO_Message
{
  /**
   * Type will be #GNUNET_MESSAGE_TYPE_HELLO.
   */
  struct GNUNET_MessageHeader header;

  /**
   * Use in F2F mode: Do not gossip this HELLO message
   */
  uint32_t friend_only GNUNET_PACKED;

  /**
   * The public key of the peer.
   */
  struct GNUNET_CRYPTO_EddsaPublicKey publicKey;

};
GNUNET_NETWORK_STRUCT_END


/**
 * Context used for building our own URI.
 */
struct GNUNET_HELLO_ComposeUriContext
{
  /**
   * Final URI.
   */
  char *uri;

  /**
   * Function for finding transport plugins by name.
   */
  GNUNET_HELLO_TransportPluginsFind plugins_find;
};


/**
 * Context for #add_address_to_hello().
 */
struct GNUNET_HELLO_ParseUriContext
{
  /**
   * Position in the URI with the next address to parse.
   */
  const char *pos;

  /**
   * Set to #GNUNET_SYSERR to indicate parse errors.
   */
  int ret;

  /**
   * Counter
   */
  unsigned int counter_total;

  /**
   * Counter skipped addresses
   */
  unsigned int counter_added;

  /**
   * Function for finding transport plugins by name.
   */
  GNUNET_HELLO_TransportPluginsFind plugins_find;
};


/**
 * Return HELLO type
 *
 * @param h HELLO Message to test
 * @return #GNUNET_YES for friend-only or #GNUNET_NO otherwise
 */
int
GNUNET_HELLO_is_friend_only (const struct GNUNET_HELLO_Message *h)
{
  if (GNUNET_YES == ntohl(h->friend_only))
    return GNUNET_YES;
  return GNUNET_NO;
}


/**
 * Copy the given address information into
 * the given buffer using the format of HELLOs.
 *
 * @param address the address
 * @param expiration expiration for the @a address
 * @param target where to copy the @a address
 * @param max maximum number of bytes to copy to target
 * @return number of bytes copied, 0 if
 *         the target buffer was not big enough.
 */
size_t
GNUNET_HELLO_add_address (const struct GNUNET_HELLO_Address *address,
                          struct GNUNET_TIME_Absolute expiration,
                          char *target,
                          size_t max)
{
  uint16_t alen;
  size_t slen;
  struct GNUNET_TIME_AbsoluteNBO exp;

  slen = strlen (address->transport_name) + 1;
  if (slen + sizeof (uint16_t) + sizeof (struct GNUNET_TIME_AbsoluteNBO) +
      address->address_length > max)
    return 0;
  exp = GNUNET_TIME_absolute_hton (expiration);
  alen = htons ((uint16_t) address->address_length);