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|
/*
This file is part of GNUnet.
Copyright (C) 2009-2013, 2016 GNUnet e.V.
GNUnet is free software: you can redistribute it and/or modify it
under the terms of the GNU Affero General Public License as published
by the Free Software Foundation, either version 3 of the License,
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
Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
SPDX-License-Identifier: AGPL3.0-or-later
*/
/**
* @file core/gnunet-service-core_kx.c
* @brief code for managing the key exchange (SET_KEY, PING, PONG) with other
* peers
* @author Christian Grothoff
*/
#include "platform.h"
#include "gnunet-service-core_kx.h"
#include "gnunet_transport_core_service.h"
#include "gnunet-service-core_sessions.h"
#include "gnunet-service-core.h"
#include "gnunet_constants.h"
#include "gnunet_signatures.h"
#include "gnunet_protocols.h"
/**
* Enable expensive (and possibly problematic for privacy!) logging of KX.
*/
#define DEBUG_KX 0
/**
* How long do we wait for SET_KEY confirmation initially?
*/
#define INITIAL_SET_KEY_RETRY_FREQUENCY \
GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 10)
/**
* What is the minimum frequency for a PING message?
*/
#define MIN_PING_FREQUENCY \
GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 5)
/**
* How often do we rekey?
*/
#define REKEY_FREQUENCY \
GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_HOURS, 12)
/**
* What time difference do we tolerate?
*/
#define REKEY_TOLERANCE \
GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 5)
/**
* What is the maximum age of a message for us to consider processing
* it? Note that this looks at the timestamp used by the other peer,
* so clock skew between machines does come into play here. So this
* should be picked high enough so that a little bit of clock skew
* does not prevent peers from connecting to us.
*/
#define MAX_MESSAGE_AGE GNUNET_TIME_UNIT_DAYS
GNUNET_NETWORK_STRUCT_BEGIN
/**
* Encapsulation for encrypted messages exchanged between
* peers. Followed by the actual encrypted data.
*/
struct EncryptedMessage
{
/**
* Message type is #GNUNET_MESSAGE_TYPE_CORE_ENCRYPTED_MESSAGE.
*/
struct GNUNET_MessageHeader header;
/**
* Random value used for IV generation.
*/
uint32_t iv_seed GNUNET_PACKED;
/**
* MAC of the encrypted message (starting at @e sequence_number),
* used to verify message integrity. Everything after this value
* (excluding this value itself) will be encrypted and
* authenticated. #ENCRYPTED_HEADER_SIZE must be set to the offset
* of the *next* field.
*/
struct GNUNET_HashCode hmac;
/**
* Sequence number, in network byte order. This field
* must be the first encrypted/decrypted field
*/
uint32_t sequence_number GNUNET_PACKED;
/**
* Reserved, always zero.
*/
uint32_t reserved GNUNET_PACKED;
/**
* Timestamp. Used to prevent replay of ancient messages
* (recent messages are caught with the sequence number).
*/
struct GNUNET_TIME_AbsoluteNBO timestamp;
};
GNUNET_NETWORK_STRUCT_END
/**
* Number of bytes (at the beginning) of `struct EncryptedMessage`
* that are NOT encrypted.
*/
#define ENCRYPTED_HEADER_SIZE \
(offsetof (struct EncryptedMessage, sequence_number))
/**
* Information about the status of a key exchange with another peer.
*/
struct GSC_KeyExchangeInfo
{
/**
* DLL.
*/
struct GSC_KeyExchangeInfo *next;
/**
* DLL.
*/
struct GSC_KeyExchangeInfo *prev;
/**
* Identity of the peer.
*/
const struct GNUNET_PeerIdentity *peer;
/**
* Message queue for sending messages to @a peer.
*/
struct GNUNET_MQ_Handle *mq;
/**
* Our message stream tokenizer (for encrypted payload).
*/
struct GNUNET_MessageStreamTokenizer *mst;
/**
* PING message we transmit to the other peer.
*/
struct PingMessage ping;
/**
* Ephemeral public ECC key of the other peer.
*/
struct GNUNET_CRYPTO_EcdhePublicKey other_ephemeral_key;
/**
* Key we use to encrypt our messages for the other peer
* (initialized by us when we do the handshake).
*/
struct GNUNET_CRYPTO_SymmetricSessionKey encrypt_key;
/**
* Key we use to decrypt messages from the other peer
* (given to us by the other peer during the handshake).
*/
struct GNUNET_CRYPTO_SymmetricSessionKey decrypt_key;
/**
* At what time did the other peer generate the decryption key?
*/
struct GNUNET_TIME_Absolute foreign_key_expires;
/**
* When should the session time out (if there are no PONGs)?
*/
struct GNUNET_TIME_Absolute timeout;
/**
* What was the last timeout we informed our monitors about?
*/
struct GNUNET_TIME_Absolute last_notify_timeout;
/**
* At what frequency are we currently re-trying SET_KEY messages?
*/
struct GNUNET_TIME_Relative set_key_retry_frequency;
/**
* ID of task used for re-trying SET_KEY and PING message.
*/
struct GNUNET_SCHEDULER_Task *retry_set_key_task;
/**
* ID of task used for sending keep-alive pings.
*/
struct GNUNET_SCHEDULER_Task *keep_alive_task;
/**
* Bit map indicating which of the 32 sequence numbers before the
* last were received (good for accepting out-of-order packets and
* estimating reliability of the connection)
*/
uint32_t last_packets_bitmap;
/**
* last sequence number received on this connection (highest)
*/
uint32_t last_sequence_number_received;
/**
* last sequence number transmitted
*/
uint32_t last_sequence_number_sent;
/**
* What was our PING challenge number (for this peer)?
*/
uint32_t ping_challenge;
/**
* #GNUNET_YES if this peer currently has excess bandwidth.
*/
int has_excess_bandwidth;
/**
* What is our connection status?
*/
enum GNUNET_CORE_KxState status;
};
/**
* Transport service.
*/
static struct GNUNET_TRANSPORT_CoreHandle *transport;
/**
* Our private key.
*/
static struct GNUNET_CRYPTO_EddsaPrivateKey my_private_key;
/**
* Our ephemeral private key.
*/
static struct GNUNET_CRYPTO_EcdhePrivateKey my_ephemeral_key;
/**
* Current message we send for a key exchange.
*/
static struct EphemeralKeyMessage current_ekm;
/**
* DLL head.
*/
static struct GSC_KeyExchangeInfo *kx_head;
/**
* DLL tail.
*/
static struct GSC_KeyExchangeInfo *kx_tail;
/**
* Task scheduled for periodic re-generation (and thus rekeying) of our
* ephemeral key.
*/
static struct GNUNET_SCHEDULER_Task *rekey_task;
/**
* Notification context for broadcasting to monitors.
*/
static struct GNUNET_NotificationContext *nc;
/**
* Calculate seed value we should use for a message.
*
* @param kx key exchange context
*/
static uint32_t
calculate_seed (struct GSC_KeyExchangeInfo *kx)
{
/* Note: may want to make this non-random and instead
derive from key material to avoid having an undetectable
side-channel */
return htonl (
GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX));
}
/**
* Inform all monitors about the KX state of the given peer.
*
* @param kx key exchange state to inform about
*/
static void
monitor_notify_all (struct GSC_KeyExchangeInfo *kx)
{
struct MonitorNotifyMessage msg;
msg.header.type = htons (GNUNET_MESSAGE_TYPE_CORE_MONITOR_NOTIFY);
msg.header.size = htons (sizeof(msg));
msg.state = htonl ((uint32_t) kx->status);
msg.peer = *kx->peer;
msg.timeout = GNUNET_TIME_absolute_hton (kx->timeout);
GNUNET_notification_context_broadcast (nc, &msg.header, GNUNET_NO);
kx->last_notify_timeout = kx->timeout;
}
/**
* Derive an authentication key from "set key" information
*
* @param akey authentication key to derive
* @param skey session key to use
* @param seed seed to use
*/
static void
derive_auth_key (struct GNUNET_CRYPTO_AuthKey *akey,
const struct GNUNET_CRYPTO_SymmetricSessionKey *skey,
uint32_t seed)
{
static const char ctx[] = "authentication key";
#if DEBUG_KX
struct GNUNET_HashCode sh;
GNUNET_CRYPTO_hash (skey, sizeof(*skey), &sh);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Deriving Auth key from SKEY %s and seed %u\n",
GNUNET_h2s (&sh),
(unsigned int) seed);
#endif
GNUNET_CRYPTO_hmac_derive_key (akey,
skey,
&seed,
sizeof(seed),
skey,
sizeof(
struct GNUNET_CRYPTO_SymmetricSessionKey),
ctx,
sizeof(ctx),
NULL);
}
/**
* Derive an IV from packet information
*
* @param iv initialization vector to initialize
* @param skey session key to use
* @param seed seed to use
* @param identity identity of the other peer to use
*/
static void
derive_iv (struct GNUNET_CRYPTO_SymmetricInitializationVector *iv,
const struct GNUNET_CRYPTO_SymmetricSessionKey *skey,
uint32_t seed,
const struct GNUNET_PeerIdentity *identity)
{
static const char ctx[] = "initialization vector";
#if DEBUG_KX
struct GNUNET_HashCode sh;
GNUNET_CRYPTO_hash (skey, sizeof(*skey), &sh);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Deriving IV from SKEY %s and seed %u for peer %s\n",
GNUNET_h2s (&sh),
(unsigned int) seed,
GNUNET_i2s (identity));
#endif
GNUNET_CRYPTO_symmetric_derive_iv (iv,
skey,
&seed,
sizeof(seed),
identity,
sizeof(struct GNUNET_PeerIdentity),
ctx,
sizeof(ctx),
NULL);
}
/**
* Derive an IV from pong packet information
*
* @param iv initialization vector to initialize
* @param skey session key to use
* @param seed seed to use
* @param challenge nonce to use
* @param identity identity of the other peer to use
*/
static void
derive_pong_iv (struct GNUNET_CRYPTO_SymmetricInitializationVector *iv,
const struct GNUNET_CRYPTO_SymmetricSessionKey *skey,
uint32_t seed,
uint32_t challenge,
const struct GNUNET_PeerIdentity *identity)
{
static const char ctx[] = "pong initialization vector";
#if DEBUG_KX
struct GNUNET_HashCode sh;
GNUNET_CRYPTO_hash (skey, sizeof(*skey), &sh);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Deriving PONG IV from SKEY %s and seed %u/%u for %s\n",
GNUNET_h2s (&sh),
(unsigned int) seed,
(unsigned int) challenge,
GNUNET_i2s (identity));
#endif
GNUNET_CRYPTO_symmetric_derive_iv (iv,
skey,
&seed,
sizeof(seed),
identity,
sizeof(struct GNUNET_PeerIdentity),
&challenge,
sizeof(challenge),
ctx,
sizeof(ctx),
NULL);
}
/**
* Derive an AES key from key material
*
* @param sender peer identity of the sender
* @param receiver peer identity of the sender
* @param key_material high entropy key material to use
* @param skey set to derived session key
*/
static void
derive_aes_key (const struct GNUNET_PeerIdentity *sender,
const struct GNUNET_PeerIdentity *receiver,
const struct GNUNET_HashCode *key_material,
struct GNUNET_CRYPTO_SymmetricSessionKey *skey)
{
static const char ctx[] = "aes key generation vector";
#if DEBUG_KX
struct GNUNET_HashCode sh;
GNUNET_CRYPTO_hash (skey, sizeof(*skey), &sh);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Deriving AES Keys for %s to %s from %s\n",
GNUNET_i2s (sender),
GNUNET_i2s2 (receiver),
GNUNET_h2s (key_material));
#endif
GNUNET_CRYPTO_kdf (skey,
sizeof(struct GNUNET_CRYPTO_SymmetricSessionKey),
ctx,
sizeof(ctx),
key_material,
sizeof(struct GNUNET_HashCode),
sender,
sizeof(struct GNUNET_PeerIdentity),
receiver,
sizeof(struct GNUNET_PeerIdentity),
NULL);
}
/**
* Encrypt size bytes from @a in and write the result to @a out. Use the
* @a kx key for outbound traffic of the given neighbour.
*
* @param kx key information context
* @param iv initialization vector to use
* @param in ciphertext
* @param out plaintext
* @param size size of @a in / @a out
*
* @return #GNUNET_OK on success
*/
static int
do_encrypt (struct GSC_KeyExchangeInfo *kx,
const struct GNUNET_CRYPTO_SymmetricInitializationVector *iv,
const void *in,
void *out,
size_t size)
{
if (size != (uint16_t) size)
{
GNUNET_break (0);
return GNUNET_NO;
}
GNUNET_assert (size == GNUNET_CRYPTO_symmetric_encrypt (in,
(uint16_t) size,
&kx->encrypt_key,
iv,
out));
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# bytes encrypted"),
size,
GNUNET_NO);
/* the following is too sensitive to write to log files by accident,
so we require manual intervention to get this one... */
#if DEBUG_KX
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Encrypted %u bytes for `%s' using key %s, IV %u\n",
(unsigned int) size,
GNUNET_i2s (kx->peer),
kx->encrypt_key.aes_key,
GNUNET_CRYPTO_crc32_n (iv, sizeof(iv)));
#endif
return GNUNET_OK;
}
/**
* Decrypt size bytes from @a in and write the result to @a out. Use
* the @a kx key for inbound traffic of the given neighbour. This
* function does NOT do any integrity-checks on the result.
*
* @param kx key information context
* @param iv initialization vector to use
* @param in ciphertext
* @param out plaintext
* @param size size of @a in / @a out
* @return #GNUNET_OK on success
*/
static int
do_decrypt (struct GSC_KeyExchangeInfo *kx,
const struct GNUNET_CRYPTO_SymmetricInitializationVector *iv,
const void *in,
void *out,
size_t size)
{
if (size != (uint16_t) size)
{
GNUNET_break (0);
return GNUNET_NO;
}
if ((kx->status != GNUNET_CORE_KX_STATE_KEY_RECEIVED) &&
(kx->status != GNUNET_CORE_KX_STATE_UP) &&
(kx->status != GNUNET_CORE_KX_STATE_REKEY_SENT))
{
GNUNET_break_op (0);
return GNUNET_SYSERR;
}
if (size != GNUNET_CRYPTO_symmetric_decrypt (in,
(uint16_t) size,
&kx->decrypt_key,
iv,
out))
{
GNUNET_break (0);
return GNUNET_SYSERR;
}
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# bytes decrypted"),
size,
GNUNET_NO);
/* the following is too sensitive to write to log files by accident,
so we require manual intervention to get this one... */
#if DEBUG_KX
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Decrypted %u bytes from `%s' using key %s, IV %u\n",
(unsigned int) size,
GNUNET_i2s (kx->peer),
kx->decrypt_key.aes_key,
GNUNET_CRYPTO_crc32_n (iv, sizeof(*iv)));
#endif
return GNUNET_OK;
}
/**
* Send our key (and encrypted PING) to the other peer.
*
* @param kx key exchange context
*/
static void
send_key (struct GSC_KeyExchangeInfo *kx);
/**
* Task that will retry #send_key() if our previous attempt failed.
*
* @param cls our `struct GSC_KeyExchangeInfo`
*/
static void
set_key_retry_task (void *cls)
{
struct GSC_KeyExchangeInfo *kx = cls;
kx->retry_set_key_task = NULL;
kx->set_key_retry_frequency =
GNUNET_TIME_STD_BACKOFF (kx->set_key_retry_frequency);
GNUNET_assert (GNUNET_CORE_KX_STATE_DOWN != kx->status);
send_key (kx);
}
/**
* Create a fresh PING message for transmission to the other peer.
*
* @param kx key exchange context to create PING for
*/
static void
setup_fresh_ping (struct GSC_KeyExchangeInfo *kx)
{
struct PingMessage pp;
struct PingMessage *pm;
struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
pm = &kx->ping;
kx->ping_challenge =
GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, UINT32_MAX);
pm->header.size = htons (sizeof(struct PingMessage));
pm->header.type = htons (GNUNET_MESSAGE_TYPE_CORE_PING);
pm->iv_seed = calculate_seed (kx);
derive_iv (&iv, &kx->encrypt_key, pm->iv_seed, kx->peer);
pp.challenge = kx->ping_challenge;
pp.target = *kx->peer;
do_encrypt (kx,
&iv,
&pp.target,
&pm->target,
sizeof(struct PingMessage)
- ((void *) &pm->target - (void *) pm));
}
/**
* Deliver P2P message to interested clients. Invokes send twice,
* once for clients that want the full message, and once for clients
* that only want the header
*
* @param cls the `struct GSC_KeyExchangeInfo`
* @param m the message
* @return #GNUNET_OK on success,
* #GNUNET_NO to stop further processing (no error)
* #GNUNET_SYSERR to stop further processing with error
*/
static int
deliver_message (void *cls, const struct GNUNET_MessageHeader *m)
{
struct GSC_KeyExchangeInfo *kx = cls;
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Decrypted message of type %d from %s\n",
ntohs (m->type),
GNUNET_i2s (kx->peer));
if (GNUNET_CORE_KX_STATE_UP != kx->status)
{
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# PAYLOAD dropped (out of order)"),
1,
GNUNET_NO);
return GNUNET_OK;
}
switch (ntohs (m->type))
{
case GNUNET_MESSAGE_TYPE_CORE_BINARY_TYPE_MAP:
case GNUNET_MESSAGE_TYPE_CORE_COMPRESSED_TYPE_MAP:
GSC_SESSIONS_set_typemap (kx->peer, m);
return GNUNET_OK;
case GNUNET_MESSAGE_TYPE_CORE_CONFIRM_TYPE_MAP:
GSC_SESSIONS_confirm_typemap (kx->peer, m);
return GNUNET_OK;
default:
GSC_CLIENTS_deliver_message (kx->peer,
m,
ntohs (m->size),
GNUNET_CORE_OPTION_SEND_FULL_INBOUND);
GSC_CLIENTS_deliver_message (kx->peer,
m,
sizeof(struct GNUNET_MessageHeader),
GNUNET_CORE_OPTION_SEND_HDR_INBOUND);
}
return GNUNET_OK;
}
static void
do_rekey (void *cls);
static void
sign_ephemeral_key ();
/**
* Function called by transport to notify us that
* a peer connected to us (on the network level).
* Starts the key exchange with the given peer.
*
* @param cls closure (NULL)
* @param pid identity of the peer to do a key exchange with
* @return key exchange information context
*/
static void *
handle_transport_notify_connect (void *cls,
const struct GNUNET_PeerIdentity *pid,
struct GNUNET_MQ_Handle *mq)
{
struct GSC_KeyExchangeInfo *kx;
struct GNUNET_HashCode h1;
struct GNUNET_HashCode h2;
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Initiating key exchange with `%s'\n",
GNUNET_i2s (pid));
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# key exchanges initiated"),
1,
GNUNET_NO);
for (kx = kx_head; NULL != kx; kx = kx->next)
{
if (0 == memcmp (pid, kx->peer, sizeof(struct GNUNET_PeerIdentity)))
break;
}
if (NULL == kx)
{
GNUNET_CRYPTO_ecdhe_key_create (&my_ephemeral_key);
sign_ephemeral_key ();
{
struct GNUNET_HashCode eh;
GNUNET_CRYPTO_hash (¤t_ekm.ephemeral_key,
sizeof(current_ekm.ephemeral_key),
&eh);
GNUNET_log (GNUNET_ERROR_TYPE_INFO,
"Starting with ephemeral key %s\n",
GNUNET_h2s (&eh));
}
kx = GNUNET_new (struct GSC_KeyExchangeInfo);
kx->mst = GNUNET_MST_create (&deliver_message, kx);
kx->mq = mq;
kx->peer = pid;
kx->set_key_retry_frequency = INITIAL_SET_KEY_RETRY_FREQUENCY;
GNUNET_CONTAINER_DLL_insert (kx_head, kx_tail, kx);
kx->status = GNUNET_CORE_KX_STATE_KEY_SENT;
monitor_notify_all (kx);
GNUNET_CRYPTO_hash (pid, sizeof(struct GNUNET_PeerIdentity), &h1);
GNUNET_CRYPTO_hash (&GSC_my_identity,
sizeof(struct GNUNET_PeerIdentity),
&h2);
if (0 < GNUNET_CRYPTO_hash_cmp (&h1, &h2))
{
/* peer with "lower" identity starts KX, otherwise we typically end up
with both peers starting the exchange and transmit the 'set key'
message twice */
send_key (kx);
}
else
{
/* peer with "higher" identity starts a delayed KX, if the "lower" peer
* does not start a KX since it sees no reasons to do so */
kx->retry_set_key_task =
GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
&set_key_retry_task,
kx);
}
}
else
{
struct GNUNET_TIME_Relative left;
left = GNUNET_TIME_absolute_get_remaining (kx->timeout);
if (0 == left.rel_value_us)
{
kx->status = GNUNET_CORE_KX_STATE_DOWN;
}
else
kx->status = GNUNET_CORE_KX_STATE_REKEY_SENT;
do_rekey (NULL);
}
return kx;
}
/**
* Function called by transport telling us that a peer
* disconnected.
* Stop key exchange with the given peer. Clean up key material.
*
* @param cls closure
* @param peer the peer that disconnected
* @param handler_cls the `struct GSC_KeyExchangeInfo` of the peer
*/
static void
handle_transport_notify_disconnect (void *cls,
const struct GNUNET_PeerIdentity *peer,
void *handler_cls)
{
struct GSC_KeyExchangeInfo *kx = handler_cls;
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Peer `%s' disconnected from us.\n",
GNUNET_i2s (peer));
GSC_SESSIONS_end (kx->peer);
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# key exchanges stopped"),
1,
GNUNET_NO);
if (NULL != kx->retry_set_key_task)
{
GNUNET_SCHEDULER_cancel (kx->retry_set_key_task);
kx->retry_set_key_task = NULL;
}
if (NULL != kx->keep_alive_task)
{
GNUNET_SCHEDULER_cancel (kx->keep_alive_task);
kx->keep_alive_task = NULL;
}
kx->status = GNUNET_CORE_KX_PEER_DISCONNECT;
monitor_notify_all (kx);
GNUNET_CONTAINER_DLL_remove (kx_head, kx_tail, kx);
GNUNET_MST_destroy (kx->mst);
GNUNET_free (kx);
}
/**
* Send our PING to the other peer.
*
* @param kx key exchange context
*/
static void
send_ping (struct GSC_KeyExchangeInfo *kx)
{
struct GNUNET_MQ_Envelope *env;
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# PING messages transmitted"),
1,
GNUNET_NO);
env = GNUNET_MQ_msg_copy (&kx->ping.header);
GNUNET_MQ_send (kx->mq, env);
}
/**
* Derive fresh session keys from the current ephemeral keys.
*
* @param kx session to derive keys for
*/
static void
derive_session_keys (struct GSC_KeyExchangeInfo *kx)
{
struct GNUNET_HashCode key_material;
if (GNUNET_OK !=
GNUNET_CRYPTO_ecc_ecdh (&my_ephemeral_key,
&kx->other_ephemeral_key,
&key_material))
{
GNUNET_break (0);
return;
}
derive_aes_key (&GSC_my_identity, kx->peer, &key_material, &kx->encrypt_key);
derive_aes_key (kx->peer, &GSC_my_identity, &key_material, &kx->decrypt_key);
memset (&key_material, 0, sizeof(key_material));
/* fresh key, reset sequence numbers */
kx->last_sequence_number_received = 0;
kx->last_packets_bitmap = 0;
setup_fresh_ping (kx);
}
/**
* We received a #GNUNET_MESSAGE_TYPE_CORE_EPHEMERAL_KEY message.
* Validate and update our key material and status.
*
* @param cls key exchange status for the corresponding peer
* @param m the set key message we received
*/
static void
handle_ephemeral_key (void *cls, const struct EphemeralKeyMessage *m)
{
struct GSC_KeyExchangeInfo *kx = cls;
struct GNUNET_TIME_Absolute start_t;
struct GNUNET_TIME_Absolute end_t;
struct GNUNET_TIME_Absolute now;
enum GNUNET_CORE_KxState sender_status;
end_t = GNUNET_TIME_absolute_ntoh (m->expiration_time);
if (((GNUNET_CORE_KX_STATE_KEY_RECEIVED == kx->status) ||
(GNUNET_CORE_KX_STATE_UP == kx->status) ||
(GNUNET_CORE_KX_STATE_REKEY_SENT == kx->status)) &&
(end_t.abs_value_us < kx->foreign_key_expires.abs_value_us))
{
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# old ephemeral keys ignored"),
1,
GNUNET_NO);
GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
"Received expired EPHEMERAL_KEY from %s\n",
GNUNET_i2s (&m->origin_identity));
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
if (0 == memcmp (&m->ephemeral_key,
&kx->other_ephemeral_key,
sizeof(m->ephemeral_key)))
{
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop (
"# duplicate ephemeral keys ignored"),
1,
GNUNET_NO);
GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
"Ignoring duplicate EPHEMERAL_KEY from %s\n",
GNUNET_i2s (&m->origin_identity));
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
if (0 != memcmp (&m->origin_identity,
kx->peer,
sizeof(struct GNUNET_PeerIdentity)))
{
GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
"Received EPHEMERAL_KEY from %s, but expected %s\n",
GNUNET_i2s (&m->origin_identity),
GNUNET_i2s_full (kx->peer));
GNUNET_break_op (0);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
if ((ntohl (m->purpose.size) !=
sizeof(struct GNUNET_CRYPTO_EccSignaturePurpose)
+ sizeof(struct GNUNET_TIME_AbsoluteNBO)
+ sizeof(struct GNUNET_TIME_AbsoluteNBO)
+ sizeof(struct GNUNET_CRYPTO_EddsaPublicKey)
+ sizeof(struct GNUNET_CRYPTO_EddsaPublicKey)) ||
(GNUNET_OK !=
GNUNET_CRYPTO_eddsa_verify_ (GNUNET_SIGNATURE_PURPOSE_SET_ECC_KEY,
&m->purpose,
&m->signature,
&m->origin_identity.public_key)))
{
/* invalid signature */
GNUNET_break_op (0);
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop (
"# EPHEMERAL_KEYs rejected (bad signature)"),
1,
GNUNET_NO);
GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
"Received EPHEMERAL_KEY from %s with bad signature\n",
GNUNET_i2s (&m->origin_identity));
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
now = GNUNET_TIME_absolute_get ();
start_t = GNUNET_TIME_absolute_ntoh (m->creation_time);
if ((end_t.abs_value_us <
GNUNET_TIME_absolute_subtract (now, REKEY_TOLERANCE).abs_value_us) ||
(start_t.abs_value_us >
GNUNET_TIME_absolute_add (now, REKEY_TOLERANCE).abs_value_us))
{
GNUNET_log (
GNUNET_ERROR_TYPE_WARNING,
_ (
"EPHEMERAL_KEY from peer `%s' rejected as its validity range does not match our system time (%llu not in [%llu,%llu]).\n"),
GNUNET_i2s (kx->peer),
(unsigned long long) now.abs_value_us,
(unsigned long long) start_t.abs_value_us,
(unsigned long long) end_t.abs_value_us);
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop (
"# EPHEMERAL_KEY messages rejected due to time"),
1,
GNUNET_NO);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
#if DEBUG_KX
{
struct GNUNET_HashCode eh;
GNUNET_CRYPTO_hash (&m->ephemeral_key, sizeof(m->ephemeral_key), &eh);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Received valid EPHEMERAL_KEY `%s' from `%s' in state %d.\n",
GNUNET_h2s (&eh),
GNUNET_i2s (kx->peer),
kx->status);
}
#endif
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# valid ephemeral keys received"),
1,
GNUNET_NO);
kx->other_ephemeral_key = m->ephemeral_key;
kx->foreign_key_expires = end_t;
derive_session_keys (kx);
/* check if we still need to send the sender our key */
sender_status = (enum GNUNET_CORE_KxState) ntohl (m->sender_status);
switch (sender_status)
{
case GNUNET_CORE_KX_STATE_DOWN:
GNUNET_break_op (0);
break;
case GNUNET_CORE_KX_STATE_KEY_SENT:
/* fine, need to send our key after updating our status, see below */
GSC_SESSIONS_reinit (kx->peer);
break;
case GNUNET_CORE_KX_STATE_KEY_RECEIVED:
/* other peer already got our key, but typemap did go down */
GSC_SESSIONS_reinit (kx->peer);
break;
case GNUNET_CORE_KX_STATE_UP:
/* other peer already got our key, typemap NOT down */
break;
case GNUNET_CORE_KX_STATE_REKEY_SENT:
/* other peer already got our key, typemap NOT down */
break;
default:
GNUNET_break (0);
break;
}
/* check if we need to confirm everything is fine via PING + PONG */
switch (kx->status)
{
case GNUNET_CORE_KX_STATE_DOWN:
GNUNET_assert (NULL == kx->keep_alive_task);
kx->status = GNUNET_CORE_KX_STATE_KEY_RECEIVED;
monitor_notify_all (kx);
if (GNUNET_CORE_KX_STATE_KEY_SENT == sender_status)
send_key (kx);
else
send_ping (kx);
break;
case GNUNET_CORE_KX_STATE_KEY_SENT:
GNUNET_assert (NULL == kx->keep_alive_task);
kx->status = GNUNET_CORE_KX_STATE_KEY_RECEIVED;
monitor_notify_all (kx);
if (GNUNET_CORE_KX_STATE_KEY_SENT == sender_status)
send_key (kx);
else
send_ping (kx);
break;
case GNUNET_CORE_KX_STATE_KEY_RECEIVED:
GNUNET_assert (NULL == kx->keep_alive_task);
if (GNUNET_CORE_KX_STATE_KEY_SENT == sender_status)
send_key (kx);
else
send_ping (kx);
break;
case GNUNET_CORE_KX_STATE_UP:
kx->status = GNUNET_CORE_KX_STATE_REKEY_SENT;
monitor_notify_all (kx);
if (GNUNET_CORE_KX_STATE_KEY_SENT == sender_status)
send_key (kx);
else
send_ping (kx);
break;
case GNUNET_CORE_KX_STATE_REKEY_SENT:
if (GNUNET_CORE_KX_STATE_KEY_SENT == sender_status)
send_key (kx);
else
send_ping (kx);
break;
default:
GNUNET_break (0);
break;
}
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
}
/**
* We received a PING message. Validate and transmit
* a PONG message.
*
* @param cls key exchange status for the corresponding peer
* @param m the encrypted PING message itself
*/
static void
handle_ping (void *cls, const struct PingMessage *m)
{
struct GSC_KeyExchangeInfo *kx = cls;
struct PingMessage t;
struct PongMessage tx;
struct PongMessage *tp;
struct GNUNET_MQ_Envelope *env;
struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# PING messages received"),
1,
GNUNET_NO);
if ((kx->status != GNUNET_CORE_KX_STATE_KEY_RECEIVED) &&
(kx->status != GNUNET_CORE_KX_STATE_UP) &&
(kx->status != GNUNET_CORE_KX_STATE_REKEY_SENT))
{
/* ignore */
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop (
"# PING messages dropped (out of order)"),
1,
GNUNET_NO);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Core service receives PING request from `%s'.\n",
GNUNET_i2s (kx->peer));
derive_iv (&iv, &kx->decrypt_key, m->iv_seed, &GSC_my_identity);
if (GNUNET_OK != do_decrypt (kx,
&iv,
&m->target,
&t.target,
sizeof(struct PingMessage)
- ((void *) &m->target - (void *) m)))
{
GNUNET_break_op (0);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
if (0 !=
memcmp (&t.target, &GSC_my_identity, sizeof(struct GNUNET_PeerIdentity)))
{
if (GNUNET_CORE_KX_STATE_REKEY_SENT != kx->status)
GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
"Decryption of PING from peer `%s' failed, PING for `%s'?\n",
GNUNET_i2s (kx->peer),
GNUNET_i2s2 (&t.target));
else
GNUNET_log (
GNUNET_ERROR_TYPE_DEBUG,
"Decryption of PING from peer `%s' failed after rekey (harmless)\n",
GNUNET_i2s (kx->peer));
GNUNET_break_op (0);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
/* construct PONG */
tx.reserved = 0;
tx.challenge = t.challenge;
tx.target = t.target;
env = GNUNET_MQ_msg (tp, GNUNET_MESSAGE_TYPE_CORE_PONG);
tp->iv_seed = calculate_seed (kx);
derive_pong_iv (&iv, &kx->encrypt_key, tp->iv_seed, t.challenge, kx->peer);
do_encrypt (kx,
&iv,
&tx.challenge,
&tp->challenge,
sizeof(struct PongMessage)
- ((void *) &tp->challenge - (void *) tp));
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# PONG messages created"),
1,
GNUNET_NO);
GNUNET_MQ_send (kx->mq, env);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
}
/**
* Task triggered when a neighbour entry is about to time out
* (and we should prevent this by sending a PING).
*
* @param cls the `struct GSC_KeyExchangeInfo`
*/
static void
send_keep_alive (void *cls)
{
struct GSC_KeyExchangeInfo *kx = cls;
struct GNUNET_TIME_Relative retry;
struct GNUNET_TIME_Relative left;
kx->keep_alive_task = NULL;
left = GNUNET_TIME_absolute_get_remaining (kx->timeout);
if (0 == left.rel_value_us)
{
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# sessions terminated by timeout"),
1,
GNUNET_NO);
GSC_SESSIONS_end (kx->peer);
kx->status = GNUNET_CORE_KX_STATE_KEY_SENT;
monitor_notify_all (kx);
send_key (kx);
return;
}
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Sending KEEPALIVE to `%s'\n",
GNUNET_i2s (kx->peer));
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# keepalive messages sent"),
1,
GNUNET_NO);
setup_fresh_ping (kx);
send_ping (kx);
retry = GNUNET_TIME_relative_max (GNUNET_TIME_relative_divide (left, 2),
MIN_PING_FREQUENCY);
kx->keep_alive_task =
GNUNET_SCHEDULER_add_delayed (retry, &send_keep_alive, kx);
}
/**
* We've seen a valid message from the other peer.
* Update the time when the session would time out
* and delay sending our keep alive message further.
*
* @param kx key exchange where we saw activity
*/
static void
update_timeout (struct GSC_KeyExchangeInfo *kx)
{
struct GNUNET_TIME_Relative delta;
kx->timeout =
GNUNET_TIME_relative_to_absolute (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT);
delta =
GNUNET_TIME_absolute_get_difference (kx->last_notify_timeout, kx->timeout);
if (delta.rel_value_us > 5LL * 1000LL * 1000LL)
{
/* we only notify monitors about timeout changes if those
are bigger than the threshold (5s) */
monitor_notify_all (kx);
}
if (NULL != kx->keep_alive_task)
GNUNET_SCHEDULER_cancel (kx->keep_alive_task);
kx->keep_alive_task = GNUNET_SCHEDULER_add_delayed (
GNUNET_TIME_relative_divide (GNUNET_CONSTANTS_IDLE_CONNECTION_TIMEOUT, 2),
&send_keep_alive,
kx);
}
/**
* We received a PONG message. Validate and update our status.
*
* @param kx key exchange context for the the PONG
* @param m the encrypted PONG message itself
*/
static void
handle_pong (void *cls, const struct PongMessage *m)
{
struct GSC_KeyExchangeInfo *kx = cls;
struct PongMessage t;
struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# PONG messages received"),
1,
GNUNET_NO);
switch (kx->status)
{
case GNUNET_CORE_KX_STATE_DOWN:
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop (
"# PONG messages dropped (connection down)"),
1,
GNUNET_NO);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
case GNUNET_CORE_KX_STATE_KEY_SENT:
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop (
"# PONG messages dropped (out of order)"),
1,
GNUNET_NO);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
case GNUNET_CORE_KX_STATE_KEY_RECEIVED:
break;
case GNUNET_CORE_KX_STATE_UP:
break;
case GNUNET_CORE_KX_STATE_REKEY_SENT:
break;
default:
GNUNET_break (0);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Core service receives PONG response from `%s'.\n",
GNUNET_i2s (kx->peer));
/* mark as garbage, just to be sure */
memset (&t, 255, sizeof(t));
derive_pong_iv (&iv,
&kx->decrypt_key,
m->iv_seed,
kx->ping_challenge,
&GSC_my_identity);
if (GNUNET_OK != do_decrypt (kx,
&iv,
&m->challenge,
&t.challenge,
sizeof(struct PongMessage)
- ((void *) &m->challenge - (void *) m)))
{
GNUNET_break_op (0);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# PONG messages decrypted"),
1,
GNUNET_NO);
if ((0 !=
memcmp (&t.target, kx->peer, sizeof(struct GNUNET_PeerIdentity))) ||
(kx->ping_challenge != t.challenge))
{
/* PONG malformed */
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Received malformed PONG wanted sender `%s' with challenge %u\n",
GNUNET_i2s (kx->peer),
(unsigned int) kx->ping_challenge);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Received malformed PONG received from `%s' with challenge %u\n",
GNUNET_i2s (&t.target),
(unsigned int) t.challenge);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Received valid PONG from `%s'\n",
GNUNET_i2s (kx->peer));
/* no need to resend key any longer */
if (NULL != kx->retry_set_key_task)
{
GNUNET_SCHEDULER_cancel (kx->retry_set_key_task);
kx->retry_set_key_task = NULL;
}
switch (kx->status)
{
case GNUNET_CORE_KX_STATE_DOWN:
GNUNET_assert (0); /* should be impossible */
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
case GNUNET_CORE_KX_STATE_KEY_SENT:
GNUNET_assert (0); /* should be impossible */
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
case GNUNET_CORE_KX_STATE_KEY_RECEIVED:
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop (
"# session keys confirmed via PONG"),
1,
GNUNET_NO);
kx->status = GNUNET_CORE_KX_STATE_UP;
monitor_notify_all (kx);
GSC_SESSIONS_create (kx->peer, kx);
GNUNET_assert (NULL == kx->keep_alive_task);
update_timeout (kx);
break;
case GNUNET_CORE_KX_STATE_UP:
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# timeouts prevented via PONG"),
1,
GNUNET_NO);
update_timeout (kx);
break;
case GNUNET_CORE_KX_STATE_REKEY_SENT:
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop (
"# rekey operations confirmed via PONG"),
1,
GNUNET_NO);
kx->status = GNUNET_CORE_KX_STATE_UP;
monitor_notify_all (kx);
update_timeout (kx);
break;
default:
GNUNET_break (0);
break;
}
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
}
/**
* Send our key to the other peer.
*
* @param kx key exchange context
*/
static void
send_key (struct GSC_KeyExchangeInfo *kx)
{
struct GNUNET_MQ_Envelope *env;
GNUNET_assert (GNUNET_CORE_KX_STATE_DOWN != kx->status);
if (NULL != kx->retry_set_key_task)
{
GNUNET_SCHEDULER_cancel (kx->retry_set_key_task);
kx->retry_set_key_task = NULL;
}
/* always update sender status in SET KEY message */
#if DEBUG_KX
{
struct GNUNET_HashCode hc;
GNUNET_CRYPTO_hash (¤t_ekm.ephemeral_key,
sizeof(current_ekm.ephemeral_key),
&hc);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Sending EPHEMERAL_KEY %s to `%s' (my status: %d)\n",
GNUNET_h2s (&hc),
GNUNET_i2s (kx->peer),
kx->status);
}
#endif
current_ekm.sender_status = htonl ((int32_t) (kx->status));
env = GNUNET_MQ_msg_copy (¤t_ekm.header);
GNUNET_MQ_send (kx->mq, env);
if (GNUNET_CORE_KX_STATE_KEY_SENT != kx->status)
send_ping (kx);
kx->retry_set_key_task =
GNUNET_SCHEDULER_add_delayed (kx->set_key_retry_frequency,
&set_key_retry_task,
kx);
}
void
GSC_KX_encrypt_and_transmit (struct GSC_KeyExchangeInfo *kx,
const void *payload,
size_t payload_size)
{
size_t used = payload_size + sizeof(struct EncryptedMessage);
char pbuf[used]; /* plaintext */
struct EncryptedMessage *em; /* encrypted message */
struct EncryptedMessage *ph; /* plaintext header */
struct GNUNET_MQ_Envelope *env;
struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
struct GNUNET_CRYPTO_AuthKey auth_key;
ph = (struct EncryptedMessage *) pbuf;
ph->sequence_number = htonl (++kx->last_sequence_number_sent);
ph->iv_seed = calculate_seed (kx);
ph->reserved = 0;
ph->timestamp = GNUNET_TIME_absolute_hton (GNUNET_TIME_absolute_get ());
GNUNET_memcpy (&ph[1], payload, payload_size);
env = GNUNET_MQ_msg_extra (em,
payload_size,
GNUNET_MESSAGE_TYPE_CORE_ENCRYPTED_MESSAGE);
em->iv_seed = ph->iv_seed;
derive_iv (&iv, &kx->encrypt_key, ph->iv_seed, kx->peer);
GNUNET_assert (GNUNET_OK == do_encrypt (kx,
&iv,
&ph->sequence_number,
&em->sequence_number,
used - ENCRYPTED_HEADER_SIZE));
#if DEBUG_KX
{
struct GNUNET_HashCode hc;
GNUNET_CRYPTO_hash (&ph->sequence_number,
used - ENCRYPTED_HEADER_SIZE,
&hc);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Encrypted payload `%s' of %u bytes for %s\n",
GNUNET_h2s (&hc),
(unsigned int) (used - ENCRYPTED_HEADER_SIZE),
GNUNET_i2s (kx->peer));
}
#endif
derive_auth_key (&auth_key, &kx->encrypt_key, ph->iv_seed);
GNUNET_CRYPTO_hmac (&auth_key,
&em->sequence_number,
used - ENCRYPTED_HEADER_SIZE,
&em->hmac);
#if DEBUG_KX
{
struct GNUNET_HashCode hc;
GNUNET_CRYPTO_hash (&auth_key, sizeof(auth_key), &hc);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"For peer %s, used AC %s to create hmac %s\n",
GNUNET_i2s (kx->peer),
GNUNET_h2s (&hc),
GNUNET_h2s2 (&em->hmac));
}
#endif
kx->has_excess_bandwidth = GNUNET_NO;
GNUNET_MQ_send (kx->mq, env);
}
/**
* We received an encrypted message. Check that it is
* well-formed (size-wise).
*
* @param cls key exchange context for encrypting the message
* @param m encrypted message
* @return #GNUNET_OK if @a msg is well-formed (size-wise)
*/
static int
check_encrypted (void *cls, const struct EncryptedMessage *m)
{
uint16_t size = ntohs (m->header.size) - sizeof(*m);
if (size < sizeof(struct GNUNET_MessageHeader))
{
GNUNET_break_op (0);
return GNUNET_SYSERR;
}
return GNUNET_OK;
}
/**
* We received an encrypted message. Decrypt, validate and
* pass on to the appropriate clients.
*
* @param cls key exchange context for encrypting the message
* @param m encrypted message
*/
static void
handle_encrypted (void *cls, const struct EncryptedMessage *m)
{
struct GSC_KeyExchangeInfo *kx = cls;
struct EncryptedMessage *pt; /* plaintext */
struct GNUNET_HashCode ph;
uint32_t snum;
struct GNUNET_TIME_Absolute t;
struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
struct GNUNET_CRYPTO_AuthKey auth_key;
uint16_t size = ntohs (m->header.size);
char buf[size] GNUNET_ALIGN;
if (GNUNET_CORE_KX_STATE_UP != kx->status)
{
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop (
"# DATA message dropped (out of order)"),
1,
GNUNET_NO);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
if (0 ==
GNUNET_TIME_absolute_get_remaining (kx->foreign_key_expires).rel_value_us)
{
GNUNET_log (
GNUNET_ERROR_TYPE_WARNING,
_ (
"Session to peer `%s' went down due to key expiration (should not happen)\n"),
GNUNET_i2s (kx->peer));
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop (
"# sessions terminated by key expiration"),
1,
GNUNET_NO);
GSC_SESSIONS_end (kx->peer);
if (NULL != kx->keep_alive_task)
{
GNUNET_SCHEDULER_cancel (kx->keep_alive_task);
kx->keep_alive_task = NULL;
}
kx->status = GNUNET_CORE_KX_STATE_KEY_SENT;
monitor_notify_all (kx);
send_key (kx);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
/* validate hash */
#if DEBUG_KX
{
struct GNUNET_HashCode hc;
GNUNET_CRYPTO_hash (&m->sequence_number, size - ENCRYPTED_HEADER_SIZE, &hc);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Received encrypted payload `%s' of %u bytes from %s\n",
GNUNET_h2s (&hc),
(unsigned int) (size - ENCRYPTED_HEADER_SIZE),
GNUNET_i2s (kx->peer));
}
#endif
derive_auth_key (&auth_key, &kx->decrypt_key, m->iv_seed);
GNUNET_CRYPTO_hmac (&auth_key,
&m->sequence_number,
size - ENCRYPTED_HEADER_SIZE,
&ph);
#if DEBUG_KX
{
struct GNUNET_HashCode hc;
GNUNET_CRYPTO_hash (&auth_key, sizeof(auth_key), &hc);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"For peer %s, used AC %s to verify hmac %s\n",
GNUNET_i2s (kx->peer),
GNUNET_h2s (&hc),
GNUNET_h2s2 (&m->hmac));
}
#endif
if (0 != memcmp (&ph, &m->hmac, sizeof(struct GNUNET_HashCode)))
{
/* checksum failed */
GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
"Failed checksum validation for a message from `%s'\n",
GNUNET_i2s (kx->peer));
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
derive_iv (&iv, &kx->decrypt_key, m->iv_seed, &GSC_my_identity);
/* decrypt */
if (GNUNET_OK != do_decrypt (kx,
&iv,
&m->sequence_number,
&buf[ENCRYPTED_HEADER_SIZE],
size - ENCRYPTED_HEADER_SIZE))
{
GNUNET_break_op (0);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Decrypted %u bytes from %s\n",
(unsigned int) (size - ENCRYPTED_HEADER_SIZE),
GNUNET_i2s (kx->peer));
pt = (struct EncryptedMessage *) buf;
/* validate sequence number */
snum = ntohl (pt->sequence_number);
if (kx->last_sequence_number_received == snum)
{
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Received duplicate message, ignoring.\n");
/* duplicate, ignore */
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# bytes dropped (duplicates)"),
size,
GNUNET_NO);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
if ((kx->last_sequence_number_received > snum) &&
(kx->last_sequence_number_received - snum > 32))
{
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Received ancient out of sequence message, ignoring.\n");
/* ancient out of sequence, ignore */
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop (
"# bytes dropped (out of sequence)"),
size,
GNUNET_NO);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
if (kx->last_sequence_number_received > snum)
{
uint32_t rotbit = 1U << (kx->last_sequence_number_received - snum - 1);
if ((kx->last_packets_bitmap & rotbit) != 0)
{
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Received duplicate message, ignoring.\n");
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# bytes dropped (duplicates)"),
size,
GNUNET_NO);
/* duplicate, ignore */
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
kx->last_packets_bitmap |= rotbit;
}
if (kx->last_sequence_number_received < snum)
{
unsigned int shift = (snum - kx->last_sequence_number_received);
if (shift >= 8 * sizeof(kx->last_packets_bitmap))
kx->last_packets_bitmap = 0;
else
kx->last_packets_bitmap <<= shift;
kx->last_sequence_number_received = snum;
}
/* check timestamp */
t = GNUNET_TIME_absolute_ntoh (pt->timestamp);
if (GNUNET_TIME_absolute_get_duration (t).rel_value_us >
MAX_MESSAGE_AGE.rel_value_us)
{
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Message received far too old (%s). Content ignored.\n",
GNUNET_STRINGS_relative_time_to_string (
GNUNET_TIME_absolute_get_duration (t),
GNUNET_YES));
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop (
"# bytes dropped (ancient message)"),
size,
GNUNET_NO);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
return;
}
/* process decrypted message(s) */
update_timeout (kx);
GNUNET_STATISTICS_update (GSC_stats,
gettext_noop ("# bytes of payload decrypted"),
size - sizeof(struct EncryptedMessage),
GNUNET_NO);
if (GNUNET_OK !=
GNUNET_MST_from_buffer (kx->mst,
&buf[sizeof(struct EncryptedMessage)],
size - sizeof(struct EncryptedMessage),
GNUNET_YES,
GNUNET_NO))
GNUNET_break_op (0);
GNUNET_TRANSPORT_core_receive_continue (transport, kx->peer);
}
/**
* Setup the message that links the ephemeral key to our persistent
* public key and generate the appropriate signature.
*/
static void
sign_ephemeral_key ()
{
current_ekm.header.size = htons (sizeof(struct EphemeralKeyMessage));
current_ekm.header.type = htons (GNUNET_MESSAGE_TYPE_CORE_EPHEMERAL_KEY);
current_ekm.sender_status = 0; /* to be set later */
current_ekm.purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_SET_ECC_KEY);
current_ekm.purpose.size =
htonl (sizeof(struct GNUNET_CRYPTO_EccSignaturePurpose)
+ sizeof(struct GNUNET_TIME_AbsoluteNBO)
+ sizeof(struct GNUNET_TIME_AbsoluteNBO)
+ sizeof(struct GNUNET_CRYPTO_EcdhePublicKey)
+ sizeof(struct GNUNET_PeerIdentity));
current_ekm.creation_time =
GNUNET_TIME_absolute_hton (GNUNET_TIME_absolute_get ());
if (GNUNET_YES == GNUNET_CONFIGURATION_get_value_yesno (GSC_cfg,
"core",
"USE_EPHEMERAL_KEYS"))
{
current_ekm.expiration_time =
GNUNET_TIME_absolute_hton (GNUNET_TIME_relative_to_absolute (
GNUNET_TIME_relative_add (REKEY_FREQUENCY,
REKEY_TOLERANCE)));
}
else
{
current_ekm.expiration_time =
GNUNET_TIME_absolute_hton (GNUNET_TIME_UNIT_FOREVER_ABS);
}
GNUNET_CRYPTO_ecdhe_key_get_public (&my_ephemeral_key,
¤t_ekm.ephemeral_key);
current_ekm.origin_identity = GSC_my_identity;
GNUNET_assert (GNUNET_OK ==
GNUNET_CRYPTO_eddsa_sign_ (&my_private_key,
¤t_ekm.purpose,
¤t_ekm.signature));
}
/**
* Task run to trigger rekeying.
*
* @param cls closure, NULL
*/
static void
do_rekey (void *cls)
{
struct GSC_KeyExchangeInfo *pos;
(void) cls;
if (NULL != rekey_task)
{
GNUNET_SCHEDULER_cancel (rekey_task);
rekey_task = NULL;
}
rekey_task = GNUNET_SCHEDULER_add_delayed (REKEY_FREQUENCY, &do_rekey, NULL);
GNUNET_CRYPTO_ecdhe_key_create (&my_ephemeral_key);
sign_ephemeral_key ();
{
struct GNUNET_HashCode eh;
GNUNET_CRYPTO_hash (¤t_ekm.ephemeral_key,
sizeof(current_ekm.ephemeral_key),
&eh);
GNUNET_log (GNUNET_ERROR_TYPE_INFO, "Rekeying to %s\n", GNUNET_h2s (&eh));
}
for (pos = kx_head; NULL != pos; pos = pos->next)
{
if (GNUNET_CORE_KX_STATE_UP == pos->status)
{
pos->status = GNUNET_CORE_KX_STATE_REKEY_SENT;
monitor_notify_all (pos);
derive_session_keys (pos);
}
if (GNUNET_CORE_KX_STATE_DOWN == pos->status)
{
pos->status = GNUNET_CORE_KX_STATE_KEY_SENT;
monitor_notify_all (pos);
}
monitor_notify_all (pos);
send_key (pos);
}
}
/**
* Initialize KX subsystem.
*
* @param pk private key to use for the peer
* @return #GNUNET_OK on success, #GNUNET_SYSERR on failure
*/
int
GSC_KX_init (struct GNUNET_CRYPTO_EddsaPrivateKey *pk)
{
struct GNUNET_MQ_MessageHandler handlers[] = {
GNUNET_MQ_hd_fixed_size (ephemeral_key,
GNUNET_MESSAGE_TYPE_CORE_EPHEMERAL_KEY,
struct EphemeralKeyMessage,
NULL),
GNUNET_MQ_hd_fixed_size (ping,
GNUNET_MESSAGE_TYPE_CORE_PING,
struct PingMessage,
NULL),
GNUNET_MQ_hd_fixed_size (pong,
GNUNET_MESSAGE_TYPE_CORE_PONG,
struct PongMessage,
NULL),
GNUNET_MQ_hd_var_size (encrypted,
GNUNET_MESSAGE_TYPE_CORE_ENCRYPTED_MESSAGE,
struct EncryptedMessage,
NULL),
GNUNET_MQ_handler_end ()
};
my_private_key = *pk;
GNUNET_CRYPTO_eddsa_key_get_public (&my_private_key,
&GSC_my_identity.public_key);
nc = GNUNET_notification_context_create (1);
rekey_task = GNUNET_SCHEDULER_add_delayed (REKEY_FREQUENCY, &do_rekey, NULL);
transport =
GNUNET_TRANSPORT_core_connect (GSC_cfg,
&GSC_my_identity,
handlers,
NULL,
&handle_transport_notify_connect,
&handle_transport_notify_disconnect);
if (NULL == transport)
{
GSC_KX_done ();
return GNUNET_SYSERR;
}
return GNUNET_OK;
}
/**
* Shutdown KX subsystem.
*/
void
GSC_KX_done ()
{
if (NULL != transport)
{
GNUNET_TRANSPORT_core_disconnect (transport);
transport = NULL;
}
if (NULL != rekey_task)
{
GNUNET_SCHEDULER_cancel (rekey_task);
rekey_task = NULL;
}
memset (&my_ephemeral_key,
0,
sizeof (my_ephemeral_key));
memset (&my_private_key,
0,
sizeof (my_private_key));
if (NULL != nc)
{
GNUNET_notification_context_destroy (nc);
nc = NULL;
}
}
/**
* Check how many messages are queued for the given neighbour.
*
* @param kxinfo data about neighbour to check
* @return number of items in the message queue
*/
unsigned int
GSC_NEIGHBOURS_get_queue_length (const struct GSC_KeyExchangeInfo *kxinfo)
{
return GNUNET_MQ_get_length (kxinfo->mq);
}
int
GSC_NEIGHBOURS_check_excess_bandwidth (const struct GSC_KeyExchangeInfo *kxinfo)
{
return kxinfo->has_excess_bandwidth;
}
/**
* Handle #GNUNET_MESSAGE_TYPE_CORE_MONITOR_PEERS request. For this
* request type, the client does not have to have transmitted an INIT
* request. All current peers are returned, regardless of which
* message types they accept.
*
* @param mq message queue to add for monitoring
*/
void
GSC_KX_handle_client_monitor_peers (struct GNUNET_MQ_Handle *mq)
{
struct GNUNET_MQ_Envelope *env;
struct MonitorNotifyMessage *done_msg;
struct GSC_KeyExchangeInfo *kx;
GNUNET_notification_context_add (nc, mq);
for (kx = kx_head; NULL != kx; kx = kx->next)
{
struct GNUNET_MQ_Envelope *env;
struct MonitorNotifyMessage *msg;
env = GNUNET_MQ_msg (msg, GNUNET_MESSAGE_TYPE_CORE_MONITOR_NOTIFY);
msg->state = htonl ((uint32_t) kx->status);
msg->peer = *kx->peer;
msg->timeout = GNUNET_TIME_absolute_hton (kx->timeout);
GNUNET_MQ_send (mq, env);
}
env = GNUNET_MQ_msg (done_msg, GNUNET_MESSAGE_TYPE_CORE_MONITOR_NOTIFY);
done_msg->state = htonl ((uint32_t) GNUNET_CORE_KX_ITERATION_FINISHED);
done_msg->timeout = GNUNET_TIME_absolute_hton (GNUNET_TIME_UNIT_FOREVER_ABS);
GNUNET_MQ_send (mq, env);
}
/* end of gnunet-service-core_kx.c */
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