src/core/or/edge_connection_st.h

   1 /* Copyright (c) 2001 Matej Pfajfar.
   2  * Copyright (c) 2001-2004, Roger Dingledine.
   3  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
   4  * Copyright (c) 2007-2021, The Tor Project, Inc. */
   5 /* See LICENSE for licensing information */
   6
   7 /**
   8  * @file edge_connection_st.h
   9  * @brief Edge-connection structure.
  10  **/
  11
  12 #ifndef EDGE_CONNECTION_ST_H
  13 #define EDGE_CONNECTION_ST_H
  14
  15 #include "core/or/or.h"
  16
  17 #include "core/or/connection_st.h"
  18 #include "lib/evloop/token_bucket.h"
  19
  20 /** Subtype of connection_t for an "edge connection" -- that is, an entry (ap)
  21  * connection, or an exit. */
  22 struct edge_connection_t {
  23   connection_t base_;
  24
  25   struct edge_connection_t *next_stream; /**< Points to the next stream at this
  26                                           * edge, if any */
  27   int package_window; /**< How many more relay cells can I send into the
  28                        * circuit? */
  29   int deliver_window; /**< How many more relay cells can end at me? */
  30
  31   struct circuit_t *on_circuit; /**< The circuit (if any) that this edge
  32                                  * connection is using. */
  33
  34   /** A pointer to which node in the circ this conn exits at.  Set for AP
  35    * connections and for hidden service exit connections. */
  36   struct crypt_path_t *cpath_layer;
  37
  38   /* Hidden service connection identifier for edge connections. Used by the HS
  39    * client-side code to identify client SOCKS connections and by the
  40    * service-side code to match HS circuits with their streams. */
  41   struct hs_ident_edge_conn_t *hs_ident;
  42
  43   uint32_t address_ttl; /**< TTL for address-to-addr mapping on exit
  44                          * connection.  Exit connections only. */
  45   uint32_t begincell_flags; /** Flags sent or received in the BEGIN cell
  46                              * for this connection */
  47
  48   streamid_t stream_id; /**< The stream ID used for this edge connection on its
  49                          * circuit */
  50
  51   /** The reason why this connection is closing; passed to the controller. */
  52   uint16_t end_reason;
  53
  54   /** Bytes read since last call to control_event_stream_bandwidth_used() */
  55   uint32_t n_read;
  56
  57   /** Bytes written since last call to control_event_stream_bandwidth_used() */
  58   uint32_t n_written;
  59
  60   /** True iff this connection is for a DNS request only. */
  61   unsigned int is_dns_request:1;
  62   /** True iff this connection is for a PTR DNS request. (exit only) */
  63   unsigned int is_reverse_dns_lookup:1;
  64
  65   unsigned int edge_has_sent_end:1; /**< For debugging; only used on edge
  66                          * connections.  Set once we've set the stream end,
  67                          * and check in connection_about_to_close_connection().
  68                          */
  69   /** True iff we've blocked reading until the circuit has fewer queued
  70    * cells. */
  71   unsigned int edge_blocked_on_circ:1;
  72
  73   /** Unique ID for directory requests; this used to be in connection_t, but
  74    * that's going away and being used on channels instead.  We still tag
  75    * edge connections with dirreq_id from circuits, so it's copied here. */
  76   uint64_t dirreq_id;
  77
  78   /* The following are flow control fields */
  79
  80   /** Used for rate limiting the read side of this edge connection when
  81    * congestion control is enabled on its circuit. The XON cell ewma_drain_rate
  82    * parameter is used to set the bucket limits. */
  83   token_bucket_rw_t bucket;
  84
  85   /**
  86    * Monotime timestamp of the last time we sent a flow control message
  87    * for this edge, used to compute advisory rates */
  88   uint64_t drain_start_usec;
  89
  90   /**
  91    * Number of bytes written since we either emptied our buffers,
  92    * or sent an advisory drate rate. Can wrap, buf if so,
  93    * we must reset the usec timestamp above. (Or make this u64, idk).
  94    */
  95   uint32_t drained_bytes;
  96   uint32_t prev_drained_bytes;
  97
  98   /**
  99    * N_EWMA of the drain rate of writes on this edge conn
 100    * while buffers were present.
 101    */
 102   uint32_t ewma_drain_rate;
 103
 104   /**
 105    * The ewma drain rate the last time we sent an xon.
 106    */
 107   uint32_t ewma_rate_last_sent;
 108
 109   /**
 110    * The following fields are used to count the total bytes sent on this
 111    * stream, and compare them to the number of XON and XOFFs recieved, so
 112    * that clients can check rate limits of XOFF/XON to prevent dropmark
 113    * attacks. */
 114   uint32_t total_bytes_xmit;
 115
 116   /** Number of XOFFs received */
 117   uint8_t num_xoff_recv;
 118
 119   /** Number of XONs received */
 120   uint8_t num_xon_recv;
 121
 122   /**
 123    * Flag that tells us if an XOFF has been sent; cleared when we send an XON.
 124    * Used to avoid sending multiple */
 125   uint8_t xoff_sent : 1;
 126
 127   /** Flag that tells us if an XOFF has been received; cleared when we get
 128    * an XON. Used to ensure that this edge keeps reads on its edge socket
 129    * disabled. */
 130   uint8_t xoff_received : 1;
 131 };
 132
 133 #endif /* !defined(EDGE_CONNECTION_ST_H) */