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#ifndef LIGHTNING_DAEMON_SPHINX_H
#define LIGHTNING_DAEMON_SPHINX_H
#include "config.h"
#include "bitcoin/privkey.h"
#include "bitcoin/pubkey.h"
#include <ccan/short_types/short_types.h>
#include <ccan/tal/tal.h>
#include <secp256k1.h>
#include <sodium/randombytes.h>
#define SECURITY_PARAMETER 20
#define NUM_MAX_HOPS 20
#define HOP_PAYLOAD_SIZE 20
#define TOTAL_HOP_PAYLOAD_SIZE (NUM_MAX_HOPS * HOP_PAYLOAD_SIZE)
#define ROUTING_INFO_SIZE (2 * NUM_MAX_HOPS * SECURITY_PARAMETER)
#define TOTAL_PACKET_SIZE (1 + 33 + SECURITY_PARAMETER + ROUTING_INFO_SIZE + \
TOTAL_HOP_PAYLOAD_SIZE)
struct onionpacket {
/* Cleartext information */
u8 version;
u8 nexthop[20];
u8 mac[20];
secp256k1_pubkey ephemeralkey;
/* Encrypted information */
u8 routinginfo[ROUTING_INFO_SIZE];
u8 hoppayloads[TOTAL_HOP_PAYLOAD_SIZE];
};
enum route_next_case {
ONION_END = 0,
ONION_FORWARD = 1,
};
/* FIXME-OLD #4:
*
* The format of the per-hop-payload for a version 0 packet is as follows:
```
+----------------+--------------------------+-------------------------------+--------------------------------------------+
| realm (1 byte) | amt_to_forward (8 bytes) | outgoing_cltv_value (4 bytes) | unused_with_v0_version_on_header (7 bytes) |
+----------------+--------------------------+-------------------------------+--------------------------------------------+
```
*/
struct hoppayload {
u8 realm;
u64 amt_to_forward;
u32 outgoing_cltv_value;
u8 unused_with_v0_version_on_header[7];
};
struct route_step {
enum route_next_case nextcase;
struct onionpacket *next;
struct hoppayload *hoppayload;
};
/**
* create_onionpacket - Create a new onionpacket that can be routed
* over a path of intermediate nodes.
*
* @ctx: tal context to allocate from
* @path: public keys of nodes along the path.
* @hoppayloads: payloads destined for individual hosts (limited to
* HOP_PAYLOAD_SIZE bytes)
* @num_hops: path length in nodes
* @sessionkey: 20 byte random session key to derive secrets from
* @assocdata: associated data to commit to in HMACs
* @assocdatalen: length of the assocdata
*/
struct onionpacket *create_onionpacket(
const tal_t * ctx,
struct pubkey path[],
struct hoppayload hoppayloads[],
const u8 * sessionkey,
const u8 *assocdata,
const size_t assocdatalen
);
/**
* onion_shared_secret - calculate ECDH shared secret between nodes.
*
* @secret: the shared secret (32 bytes long)
* @pubkey: the public key of the other node
* @privkey: the private key of this node (32 bytes long)
*/
bool onion_shared_secret(
u8 *secret,
const struct onionpacket *packet,
const struct privkey *privkey);
/**
* process_onionpacket - process an incoming packet by stripping one
* onion layer and return the packet for the next hop.
*
* @ctx: tal context to allocate from
* @packet: incoming packet being processed
* @shared_secret: the result of onion_shared_secret.
* @hoppayload: the per-hop payload destined for the processing node.
* @assocdata: associated data to commit to in HMACs
* @assocdatalen: length of the assocdata
*/
struct route_step *process_onionpacket(
const tal_t * ctx,
const struct onionpacket *packet,
const u8 *shared_secret,
const u8 *assocdata,
const size_t assocdatalen
);
/**
* serialize_onionpacket - Serialize an onionpacket to a buffer.
*
* @ctx: tal context to allocate from
* @packet: the packet to serialize
*/
u8 *serialize_onionpacket(
const tal_t *ctx,
const struct onionpacket *packet);
/**
* parese_onionpacket - Parse an onionpacket from a buffer.
*
* @ctx: tal context to allocate from
* @src: buffer to read the packet from
* @srclen: length of the @src
*/
struct onionpacket *parse_onionpacket(
const tal_t *ctx,
const void *src,
const size_t srclen
);
#endif /* LIGHTNING_DAEMON_SPHINX_H */