c-libp2p/include/libp2p/conn/session.h

#pragma once
#include <pthread.h>
#include "libp2p/crypto/key.h"
#include "libp2p/db/datastore.h"
#include "libp2p/db/filestore.h"

/***
 * Holds the details of communication between two hosts
 *
 * NOTE: This needs a deep cleaning. The links between c-ipfs and c-libp2p should
 * be clearly defined. This seems to tie the two together inappropriately.
 */

enum IPTrafficType { TCP, UDP };

struct SessionContext {
	// to get the connection started
	char* host;
	int port;
	enum IPTrafficType traffic_type;
	pthread_mutex_t stream_mutex;
	// once the connection is established
	/**
	 * Note: default_stream should be used in most cases. Often, insecure_stream and secure_stream will be
	 * the same. This should be re-thought, probably better named, and simplified. Perhaps 1 stream and
	 * indicators regarding which protocols have been negotiated (i.e. multistream over secio)?
	 */
	struct Stream* insecure_stream;
	struct Stream* secure_stream;
	struct Stream* default_stream;
	struct Datastore* datastore;
	struct Filestore* filestore;
	// filled in during negotiations
	char* chosen_curve;
	char* chosen_cipher;
	char* chosen_hash;
	unsigned char* shared_key; // a shared key based off of the ephemeral private key
	size_t shared_key_size;
	//unsigned char* mac;
	//size_t mac_size;
	// the following items carry state for the sha256 stream cipher, and should probably not be touched.
	size_t aes_encode_nonce_offset;
	unsigned char aes_encode_stream_block[16];
	size_t aes_decode_nonce_offset;
	unsigned char aes_decode_stream_block[16];
	/**
	 * The mac function to use
	 * @param 1 the incoming data bytes
	 * @param 2 the size of the incoming array
	 * @param 3 the results. Must be allocated to correct size (or larger)
	 * @returns true(1) on success, false(0) otherwise
	 */
	int (*mac_function)(const unsigned char*, size_t, unsigned char*);
	// local only stuff
	unsigned char local_nonce[16];
	struct EphemeralPrivateKey* ephemeral_private_key;
	struct StretchedKey* local_stretched_key;
	// remote stuff
	unsigned char remote_nonce[16];
	struct PublicKey remote_key;
	char* remote_peer_id;
	struct StretchedKey* remote_stretched_key;
	unsigned char* remote_ephemeral_public_key;
	size_t remote_ephemeral_public_key_size;
	unsigned long long last_comm_epoch;
};

/***
 * Allocate resources for a new SessionContext struct
 * @returns the newly allocated SessionContext, or NULL
 */
struct SessionContext* libp2p_session_context_new();
/**
 * Free resources of a SessionContext struct
 * @param context the SessionContext
 * @returns true(1)
 */
int libp2p_session_context_free(struct SessionContext* session);

/***
 * Compare 2 SessionContext structs for equality
 * @param a side A
 * @param b side B
 * @returns 0 if equal, <0 if A wins, >0 if B wins
 */
int libp2p_session_context_compare(const struct SessionContext* a, const struct SessionContext* b);

struct SessionContext* libp2p_session_context_copy(const struct SessionContext* original);