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/* Copyright (c) 2001 Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2021, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* @file edge_connection_st.h
* @brief Edge-connection structure.
**/
#ifndef EDGE_CONNECTION_ST_H
#define EDGE_CONNECTION_ST_H
#include "core/or/or.h"
#include "core/or/connection_st.h"
#include "lib/evloop/token_bucket.h"
/** Subtype of connection_t for an "edge connection" -- that is, an entry (ap)
* connection, or an exit. */
struct edge_connection_t {
connection_t base_;
struct edge_connection_t *next_stream; /**< Points to the next stream at this
* edge, if any */
int package_window; /**< How many more relay cells can I send into the
* circuit? */
int deliver_window; /**< How many more relay cells can end at me? */
struct circuit_t *on_circuit; /**< The circuit (if any) that this edge
* connection is using. */
/** A pointer to which node in the circ this conn exits at. Set for AP
* connections and for hidden service exit connections. */
struct crypt_path_t *cpath_layer;
/* Hidden service connection identifier for edge connections. Used by the HS
* client-side code to identify client SOCKS connections and by the
* service-side code to match HS circuits with their streams. */
struct hs_ident_edge_conn_t *hs_ident;
uint32_t address_ttl; /**< TTL for address-to-addr mapping on exit
* connection. Exit connections only. */
uint32_t begincell_flags; /** Flags sent or received in the BEGIN cell
* for this connection */
streamid_t stream_id; /**< The stream ID used for this edge connection on its
* circuit */
/** The reason why this connection is closing; passed to the controller. */
uint16_t end_reason;
/** Bytes read since last call to control_event_stream_bandwidth_used() */
uint32_t n_read;
/** Bytes written since last call to control_event_stream_bandwidth_used() */
uint32_t n_written;
/** True iff this connection is for a DNS request only. */
unsigned int is_dns_request:1;
/** True iff this connection is for a PTR DNS request. (exit only) */
unsigned int is_reverse_dns_lookup:1;
unsigned int edge_has_sent_end:1; /**< For debugging; only used on edge
* connections. Set once we've set the stream end,
* and check in connection_about_to_close_connection().
*/
/** True iff we've blocked reading until the circuit has fewer queued
* cells. */
unsigned int edge_blocked_on_circ:1;
/** Unique ID for directory requests; this used to be in connection_t, but
* that's going away and being used on channels instead. We still tag
* edge connections with dirreq_id from circuits, so it's copied here. */
uint64_t dirreq_id;
/* The following are flow control fields */
/** Used for rate limiting the read side of this edge connection when
* congestion control is enabled on its circuit. The XON cell ewma_drain_rate
* parameter is used to set the bucket limits. */
token_bucket_rw_t bucket;
/**
* Monotime timestamp of the last time we sent a flow control message
* for this edge, used to compute advisory rates */
uint64_t drain_start_usec;
/**
* Number of bytes written since we either emptied our buffers,
* or sent an advisory drate rate. Can wrap, buf if so,
* we must reset the usec timestamp above. (Or make this u64, idk).
*/
uint32_t drained_bytes;
uint32_t prev_drained_bytes;
/**
* N_EWMA of the drain rate of writes on this edge conn
* while buffers were present.
*/
uint32_t ewma_drain_rate;
/**
* The ewma drain rate the last time we sent an xon.
*/
uint32_t ewma_rate_last_sent;
/**
* The following fields are used to count the total bytes sent on this
* stream, and compare them to the number of XON and XOFFs recieved, so
* that clients can check rate limits of XOFF/XON to prevent dropmark
* attacks. */
uint32_t total_bytes_xmit;
/** Number of XOFFs received */
uint8_t num_xoff_recv;
/** Number of XONs received */
uint8_t num_xon_recv;
/**
* Flag that tells us if an XOFF has been sent; cleared when we send an XON.
* Used to avoid sending multiple */
uint8_t xoff_sent : 1;
/** Flag that tells us if an XOFF has been received; cleared when we get
* an XON. Used to ensure that this edge keeps reads on its edge socket
* disabled. */
uint8_t xoff_received : 1;
};
#endif /* !defined(EDGE_CONNECTION_ST_H) */
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