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/*
* pdesc.h
* ptunnel is licensed under the BSD license:
*
* Copyright (c) 2004-2011, Daniel Stoedle <daniels@cs.uit.no>,
* Yellow Lemon Software. All rights reserved.
*
* Copyright (c) 2017-2019, Toni Uhlig <matzeton@googlemail.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* - Neither the name of the Yellow Lemon Software nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* Contacting the author:
* You can get in touch with me, Daniel Stødle (that's the Norwegian letter oe,
* in case your text editor didn't realize), here: <daniels@cs.uit.no>
*
* The official ptunnel website is here:
* <http://www.cs.uit.no/~daniels/PingTunnel/>
*
* Note that the source code is best viewed with tabs set to 4 spaces.
*/
#ifndef PDESC_H
#define PDESC_H 1
#include <stdint.h>
#ifndef WIN32
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#endif
#include "pkt.h"
#include "challenge.h"
#include "pconfig.h"
/** forward_desc_t: Describes a piece of that needs to be forwarded. This
* structure is used for receiving data from the network, and for subsequent
* forwarding over TCP:
*
* 1. Client sends data to proxy over ICMP
* 2. Proxy receives the data, and puts it into a forward_desc_t
* 3. The proxy starts send()-ing the data over the TCP socket to the destination,
* decreasing forward_desc_t->remaining with the number of bytes transferred.
* 4. Once remaining reaches 0, the forward_desc_t is removed from the receive
* ring.
*
* The same procedure is followed in proxy-to-client communication. Just replace
* proxy with client and vice versa in the list above.
*/
typedef struct forward_desc_t {
/** ping_tunnel_pkt_t seq_no */
uint16_t seq_no;
/** length of data */
uint16_t length;
/** amount of data not yet transferred */
size_t remaining;
char data[0];
} forward_desc_t;
/** icmp_desc_t: This structure is used to track the ICMP packets sent by either
* the client or proxy. The last_resend variable is used to prevent resending
* the packet too often. Once the packet is acknowledged by the remote end,
* it will be removed from the send-ring, freeing up space for more outgoing
* ICMP packets.
*/
typedef struct icmp_desc_t {
/** total length of ICMP packet, including ICMP header and ptunnel data. */
uint16_t pkt_len;
double last_resend;
uint16_t seq_no;
uint16_t icmp_id;
icmp_echo_packet_t * pkt;
} icmp_desc_t;
/** xfer_stats_t: Various transfer statistics, such as bytes sent and received,
* number of ping packets sent/received, etc.
*/
typedef struct xfer_stats_t {
double bytes_in;
double bytes_out;
uint32_t icmp_in;
uint32_t icmp_out;
uint32_t icmp_resent;
uint32_t icmp_ack_out;
} xfer_stats_t;
/** proxy_desc_t: This massive structure describes a tunnel instance.
*/
typedef struct proxy_desc_t {
/** ICMP or UDP socket */
int sock;
/** number of bytes in receive buffer */
int bytes;
/** set to true once this instance should be removed */
int should_remove;
/** data buffer, used to receive ping and pong packets */
char * buf;
uint16_t id_no;
uint16_t my_seq;
uint16_t ping_seq;
uint16_t next_remote_seq;
uint16_t pkt_type;
uint16_t remote_ack_val;
uint16_t icmp_id;
/** first available slot in recv ring */
int recv_idx;
/** current slot in recv ring being transferred */
int recv_xfer_idx;
/** first available slot in send ring */
int send_idx;
/** first packet in send ring not yet acked */
int send_first_ack;
/** number of items in recv ring awaiting send */
int recv_wait_send;
/** number of items in send ring awaiting ack */
int send_wait_ack;
int next_resend_start;
int authenticated;
/** Contains the challenge, if used. */
challenge_t * challenge;
/** Protocol state */
uint32_t state;
/** Either kProxy_flag or kUser_flag */
enum pkt_flag type_flag;
/** IP and port to which data should be forwarded. */
uint32_t dst_ip;
uint32_t dst_port;
/** Same as above */
struct sockaddr_in dest_addr;
/** Time when last ack packet was sent. */
double last_ack;
/** Time when a packet was last received. */
double last_activity;
double last_data_activity;
uint16_t window_size;
double ack_interval;
double resend_interval;
icmp_desc_t * send_ring;
forward_desc_t ** recv_ring;
xfer_stats_t xfer;
struct proxy_desc_t * next;
} proxy_desc_t;
proxy_desc_t * create_and_insert_proxy_desc(uint16_t id_no,
uint16_t icmp_id,
int sock,
struct sockaddr_in * addr,
uint32_t dst_ip,
uint32_t dst_port,
uint32_t init_state,
enum pkt_flag type);
void remove_proxy_desc(proxy_desc_t * cur, proxy_desc_t * prev);
void remove_proxy_desc_rings(proxy_desc_t * cur);
forward_desc_t * create_fwd_desc(uint16_t seq_no, uint32_t data_len, char * data);
int queue_packet(
int sock_fd, proxy_desc_t * cur, char * buf, size_t bufsiz, uint32_t dest_ip, uint32_t dest_port, uint32_t state);
uint32_t send_packets(forward_desc_t * ring[], int * xfer_idx, int * await_send, int * sock, uint16_t window_size);
#endif
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