slitheen/relay_station/relay.h

/* Slitheen - a decoy routing system for censorship resistance
 * Copyright (C) 2017 Cecylia Bocovich (cbocovic@uwaterloo.ca)
 *
 * 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, version 3.
 *
 * 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 <http://www.gnu.org/licenses/>.
 *
 * Additional permission under GNU GPL version 3 section 7
 * 
 * If you modify this Program, or any covered work, by linking or combining
 * it with the OpenSSL library (or a modified version of that library), 
 * containing parts covered by the terms of [name of library's license],
 * the licensors of this Program grant you additional permission to convey
 * the resulting work. {Corresponding Source for a non-source form of such
 * a combination shall include the source code for the parts of the OpenSSL
 * library used as well as that of the covered work.}
 */
#ifndef _RELAY_H_
#define _RELAY_H_

#include "flow.h"
#include <stdint.h>

struct proxy_thread_data {
	uint8_t *initial_data;
	uint16_t initial_len;
	uint16_t stream_id;
	int32_t pipefd;
	stream_table *streams;
	data_queue *downstream_queue;
	client *client;
};

typedef struct client_st {
	uint8_t slitheen_id[SLITHEEN_ID_LEN];
	stream_table *streams;
	data_queue *downstream_queue;
	sem_t queue_lock;
	uint16_t encryption_counter;
	struct client_st *next;
	uint8_t *header_key;
	uint8_t *body_key;
	//uint8_t *mac_key
	//EVP_CIPHER_CTX *header_ctx;
	//EVP_CIPHER_CTX *body_ctx;
	EVP_MD_CTX *mac_ctx;
} client;

typedef struct client_table_st {
	client *first;
} client_table;

extern client_table *clients;

struct socks_req {
	uint8_t version;
	uint8_t cmd;
	uint8_t rsvd;
	uint8_t addr_type;
};

struct __attribute__((__packed__)) sl_up_hdr {
	uint16_t stream_id;
	uint16_t len;
};

int replace_packet(flow *f, struct packet_info *info);
int process_downstream(flow *f, int32_t offset, struct packet_info *info);
int read_header(flow *f, struct packet_info *info);
uint32_t get_response_length(uint8_t *response);
int fill_with_downstream(flow *f, uint8_t *data, int32_t length);
uint16_t tcp_checksum(struct packet_info *info);

void *proxy_covert_site(void *data);

#define BEGIN_HEADER 0x10
#define PARSE_HEADER 0x20
#define MID_CONTENT 0x30
#define BEGIN_CHUNK 0x40
#define MID_CHUNK 0x50
#define END_CHUNK 0x60
#define END_BODY 0x70
#define FORFEIT_REST 0x80
#define USE_REST 0x90

#endif /* _RELAY_H_ */