src/core/or/channel.h

   1 /* * Copyright (c) 2012-2021, The Tor Project, Inc. */
   2 /* See LICENSE for licensing information */
   3
   4 /**
   5  * \file channel.h
   6  * \brief Header file for channel.c
   7  **/
   8
   9 #ifndef TOR_CHANNEL_H
  10 #define TOR_CHANNEL_H
  11
  12 #include "core/or/or.h"
  13 #include "core/or/circuitmux.h"
  14 #include "lib/container/handles.h"
  15 #include "lib/crypt_ops/crypto_ed25519.h"
  16
  17 #include "ext/ht.h"
  18 #include "tor_queue.h"
  19
  20 #define tor_timer_t timeout
  21 struct tor_timer_t;
  22
  23 /* Channel handler function pointer typedefs */
  24 typedef void (*channel_listener_fn_ptr)(channel_listener_t *, channel_t *);
  25 typedef void (*channel_cell_handler_fn_ptr)(channel_t *, cell_t *);
  26
  27 /**
  28  * This enum is used by channelpadding to decide when to pad channels.
  29  * Don't add values to it without updating the checks in
  30  * channelpadding_decide_to_pad_channel().
  31  */
  32 typedef enum {
  33     CHANNEL_USED_NOT_USED_FOR_FULL_CIRCS = 0,
  34     CHANNEL_USED_FOR_FULL_CIRCS,
  35     CHANNEL_USED_FOR_USER_TRAFFIC,
  36 } channel_usage_info_t;
  37
  38 /** Possible rules for generating circuit IDs on an OR connection. */
  39 typedef enum {
  40   CIRC_ID_TYPE_LOWER=0, /**< Pick from 0..1<<15-1. */
  41   CIRC_ID_TYPE_HIGHER=1, /**< Pick from 1<<15..1<<16-1. */
  42   /** The other side of a connection is an OP: never create circuits to it,
  43    * and let it use any circuit ID it wants. */
  44   CIRC_ID_TYPE_NEITHER=2
  45 } circ_id_type_t;
  46 #define circ_id_type_bitfield_t ENUM_BF(circ_id_type_t)
  47
  48 /* channel states for channel_t */
  49
  50 typedef enum {
  51   /**
  52    * Closed state - channel is inactive
  53    *
  54    * Permitted transitions from:
  55    *   - CHANNEL_STATE_CLOSING
  56    * Permitted transitions to:
  57    *   - CHANNEL_STATE_OPENING
  58    */
  59   CHANNEL_STATE_CLOSED = 0,
  60   /**
  61    * Opening state - channel is trying to connect
  62    *
  63    * Permitted transitions from:
  64    *   - CHANNEL_STATE_CLOSED
  65    * Permitted transitions to:
  66    *   - CHANNEL_STATE_CLOSING
  67    *   - CHANNEL_STATE_ERROR
  68    *   - CHANNEL_STATE_OPEN
  69    */
  70   CHANNEL_STATE_OPENING,
  71   /**
  72    * Open state - channel is active and ready for use
  73    *
  74    * Permitted transitions from:
  75    *   - CHANNEL_STATE_MAINT
  76    *   - CHANNEL_STATE_OPENING
  77    * Permitted transitions to:
  78    *   - CHANNEL_STATE_CLOSING
  79    *   - CHANNEL_STATE_ERROR
  80    *   - CHANNEL_STATE_MAINT
  81    */
  82   CHANNEL_STATE_OPEN,
  83   /**
  84    * Maintenance state - channel is temporarily offline for subclass specific
  85    *   maintenance activities such as TLS renegotiation.
  86    *
  87    * Permitted transitions from:
  88    *   - CHANNEL_STATE_OPEN
  89    * Permitted transitions to:
  90    *   - CHANNEL_STATE_CLOSING
  91    *   - CHANNEL_STATE_ERROR
  92    *   - CHANNEL_STATE_OPEN
  93    */
  94   CHANNEL_STATE_MAINT,
  95   /**
  96    * Closing state - channel is shutting down
  97    *
  98    * Permitted transitions from:
  99    *   - CHANNEL_STATE_MAINT
 100    *   - CHANNEL_STATE_OPEN
 101    * Permitted transitions to:
 102    *   - CHANNEL_STATE_CLOSED,
 103    *   - CHANNEL_STATE_ERROR
 104    */
 105   CHANNEL_STATE_CLOSING,
 106   /**
 107    * Error state - channel has experienced a permanent error
 108    *
 109    * Permitted transitions from:
 110    *   - CHANNEL_STATE_CLOSING
 111    *   - CHANNEL_STATE_MAINT
 112    *   - CHANNEL_STATE_OPENING
 113    *   - CHANNEL_STATE_OPEN
 114    * Permitted transitions to:
 115    *   - None
 116    */
 117   CHANNEL_STATE_ERROR,
 118   /**
 119    * Placeholder for maximum state value
 120    */
 121   CHANNEL_STATE_LAST
 122 } channel_state_t;
 123
 124 /* channel listener states for channel_listener_t */
 125
 126 typedef enum {
 127   /**
 128    * Closed state - channel listener is inactive
 129    *
 130    * Permitted transitions from:
 131    *   - CHANNEL_LISTENER_STATE_CLOSING
 132    * Permitted transitions to:
 133    *   - CHANNEL_LISTENER_STATE_LISTENING
 134    */
 135   CHANNEL_LISTENER_STATE_CLOSED = 0,
 136   /**
 137    * Listening state - channel listener is listening for incoming
 138    * connections
 139    *
 140    * Permitted transitions from:
 141    *   - CHANNEL_LISTENER_STATE_CLOSED
 142    * Permitted transitions to:
 143    *   - CHANNEL_LISTENER_STATE_CLOSING
 144    *   - CHANNEL_LISTENER_STATE_ERROR
 145    */
 146   CHANNEL_LISTENER_STATE_LISTENING,
 147   /**
 148    * Closing state - channel listener is shutting down
 149    *
 150    * Permitted transitions from:
 151    *   - CHANNEL_LISTENER_STATE_LISTENING
 152    * Permitted transitions to:
 153    *   - CHANNEL_LISTENER_STATE_CLOSED,
 154    *   - CHANNEL_LISTENER_STATE_ERROR
 155    */
 156   CHANNEL_LISTENER_STATE_CLOSING,
 157   /**
 158    * Error state - channel listener has experienced a permanent error
 159    *
 160    * Permitted transitions from:
 161    *   - CHANNEL_STATE_CLOSING
 162    *   - CHANNEL_STATE_LISTENING
 163    * Permitted transitions to:
 164    *   - None
 165    */
 166   CHANNEL_LISTENER_STATE_ERROR,
 167   /**
 168    * Placeholder for maximum state value
 169    */
 170   CHANNEL_LISTENER_STATE_LAST
 171 } channel_listener_state_t;
 172
 173 /**
 174  * Channel struct; see the channel_t typedef in or.h.  A channel is an
 175  * abstract interface for the OR-to-OR connection, similar to connection_or_t,
 176  * but without the strong coupling to the underlying TLS implementation.  They
 177  * are constructed by calling a protocol-specific function to open a channel
 178  * to a particular node, and once constructed support the abstract operations
 179  * defined below.
 180  */
 181 struct channel_t {
 182   /** Magic number for type-checking cast macros */
 183   uint32_t magic;
 184
 185   /** List entry for hashtable for global-identifier lookup. */
 186   HT_ENTRY(channel_t) gidmap_node;
 187
 188   /** Handle entry for handle-based lookup */
 189   HANDLE_ENTRY(channel, channel_t);
 190
 191   /** Current channel state */
 192   channel_state_t state;
 193
 194   /** Globally unique ID number for a channel over the lifetime of a Tor
 195    * process.  This may not be 0.
 196    */
 197   uint64_t global_identifier;
 198
 199   /** Should we expect to see this channel in the channel lists? */
 200   unsigned char registered:1;
 201
 202   /** has this channel ever been open? */
 203   unsigned int has_been_open:1;
 204
 205   /**
 206    * This field indicates if the other side has enabled or disabled
 207    * padding via either the link protocol version or
 208    * channelpadding_negotiate cells.
 209    *
 210    * Clients can override this with ConnectionPadding in torrc to
 211    * disable or force padding to relays, but relays cannot override the
 212    * client's request.
 213    */
 214   unsigned int padding_enabled:1;
 215
 216   /** Cached value of our decision to pad (to avoid expensive
 217    * checks during critical path statistics counting). */
 218   unsigned int currently_padding:1;
 219
 220   /** Is there a pending netflow padding callback? */
 221   unsigned int pending_padding_callback:1;
 222
 223   /** Is our peer likely to consider this channel canonical? */
 224   unsigned int is_canonical_to_peer:1;
 225
 226   /** Has this channel ever been used for non-directory traffic?
 227    * Used to decide what channels to pad, and when. */
 228   channel_usage_info_t channel_usage;
 229
 230   /** When should we send a cell for netflow padding? 0 means no padding is
 231    *  scheduled. */
 232   monotime_coarse_t next_padding_time;
 233
 234   /** The callback pointer for the padding callbacks */
 235   struct tor_timer_t *padding_timer;
 236   /** The handle to this channel (to free on canceled timers) */
 237   struct channel_handle_t *timer_handle;
 238
 239   /** If not UNSPEC, the address that the peer says we have. */
 240   tor_addr_t addr_according_to_peer;
 241
 242   /**
 243    * These two fields specify the minimum and maximum negotiated timeout
 244    * values for inactivity (send or receive) before we decide to pad a
 245    * channel. These fields can be set either via a PADDING_NEGOTIATE cell,
 246    * or the torrc option ReducedConnectionPadding. The consensus parameters
 247    * nf_ito_low and nf_ito_high are used to ensure that padding can only be
 248    * negotiated to be less frequent than what is specified in the consensus.
 249    * (This is done to prevent wingnut clients from requesting excessive
 250    * padding).
 251    *
 252    * The actual timeout value is randomly chosen between these two values
 253    * as per the table in channelpadding_get_netflow_inactive_timeout_ms(),
 254    * after ensuring that these values do not specify lower timeouts than
 255    * the consensus parameters.
 256    *
 257    * If these are 0, we have not negotiated or specified custom padding
 258    * times, and instead use consensus defaults. */
 259   uint16_t padding_timeout_low_ms;
 260   uint16_t padding_timeout_high_ms;
 261
 262   /** Why did we close?
 263    */
 264   enum {
 265     CHANNEL_NOT_CLOSING = 0,
 266     CHANNEL_CLOSE_REQUESTED,
 267     CHANNEL_CLOSE_FROM_BELOW,
 268     CHANNEL_CLOSE_FOR_ERROR
 269   } reason_for_closing;
 270
 271   /** State variable for use by the scheduler */
 272   enum {
 273     /**
 274      * The channel is not open, or it has a full output buffer but no queued
 275      * cells.
 276      */
 277     SCHED_CHAN_IDLE = 0,
 278     /**
 279      * The channel has space on its output buffer to write, but no queued
 280      * cells.
 281      */
 282     SCHED_CHAN_WAITING_FOR_CELLS,
 283     /**
 284      * The scheduler has queued cells but no output buffer space to write.
 285      */
 286     SCHED_CHAN_WAITING_TO_WRITE,
 287     /**
 288      * The scheduler has both queued cells and output buffer space, and is
 289      * eligible for the scheduler loop.
 290      */
 291     SCHED_CHAN_PENDING
 292   } scheduler_state;
 293
 294   /** Heap index for use by the scheduler */
 295   int sched_heap_idx;
 296
 297   /** Timestamps for both cell channels and listeners */
 298   time_t timestamp_created; /* Channel created */
 299   time_t timestamp_active; /* Any activity */
 300
 301   /**
 302    * This is a monotonic timestamp that marks when we
 303    * believe the channel has actually sent or received data to/from
 304    * the wire. Right now, it is used to determine when we should send
 305    * a padding cell for channelpadding.
 306    *
 307    * XXX: Are we setting timestamp_xfer_ms in the right places to
 308    * accurately reflect actual network data transfer? Or might this be
 309    * very wrong wrt when bytes actually go on the wire?
 310    */
 311   monotime_coarse_t timestamp_xfer;
 312
 313   /* Methods implemented by the lower layer */
 314
 315   /** Free a channel */
 316   void (*free_fn)(channel_t *);
 317   /** Close an open channel */
 318   void (*close)(channel_t *);
 319   /** Describe the transport subclass for this channel */
 320   const char * (*describe_transport)(channel_t *);
 321   /** Optional method to dump transport-specific statistics on the channel */
 322   void (*dumpstats)(channel_t *, int);
 323
 324   /** Registered handlers for incoming cells */
 325   channel_cell_handler_fn_ptr cell_handler;
 326
 327   /* Methods implemented by the lower layer */
 328
 329   /**
 330    * Ask the lower layer for an estimate of the average overhead for
 331    * transmissions on this channel.
 332    */
 333   double (*get_overhead_estimate)(channel_t *);
 334   /*
 335    * Ask the underlying transport what the remote endpoint address is, in a
 336    * tor_addr_t.  Write the address out to the provided tor_addr_t *, and
 337    * return 1 if successful or 0 if no address available.
 338    */
 339   int (*get_remote_addr)(const channel_t *, tor_addr_t *);
 340   int (*get_transport_name)(channel_t *chan, char **transport_out);
 341
 342   /**
 343    * Get a human-readable text description of the remote endpoint, for
 344    * logging.
 345    */
 346   const char * (*describe_peer)(const channel_t *);
 347   /** Check if the lower layer has queued writes */
 348   int (*has_queued_writes)(channel_t *);
 349   /**
 350    * Ask the lower layer if this is 'canonical', for a transport-specific
 351    * definition of canonical.
 352    */
 353   int (*is_canonical)(channel_t *);
 354   /** Check if this channel matches a specified extend_info_t */
 355   int (*matches_extend_info)(channel_t *, extend_info_t *);
 356   /** Check if this channel matches a target address when extending */
 357   int (*matches_target)(channel_t *, const tor_addr_t *);
 358   /* Ask the lower layer how many bytes it has queued but not yet sent */
 359   size_t (*num_bytes_queued)(channel_t *);
 360   /* Ask the lower layer how many cells can be written */
 361   int (*num_cells_writeable)(channel_t *);
 362   /* Write a cell to an open channel */
 363   int (*write_cell)(channel_t *, cell_t *);
 364   /** Write a packed cell to an open channel */
 365   int (*write_packed_cell)(channel_t *, packed_cell_t *);
 366   /** Write a variable-length cell to an open channel */
 367   int (*write_var_cell)(channel_t *, var_cell_t *);
 368
 369   /**
 370    * Hash of the public RSA key for the other side's RSA identity key -- or
 371    * zeroes if we don't have an RSA identity in mind for the other side, and
 372    * it hasn't shown us one.
 373    *
 374    * Note that this is the RSA identity that we hope the other side has -- not
 375    * necessarily its true identity.  Don't believe this identity unless
 376    * authentication has happened.
 377    */
 378   char identity_digest[DIGEST_LEN];
 379   /**
 380    * Ed25519 key for the other side of this channel -- or zeroes if we don't
 381    * have an Ed25519 identity in mind for the other side, and it hasn't shown
 382    * us one.
 383    *
 384    * Note that this is the identity that we hope the other side has -- not
 385    * necessarily its true identity.  Don't believe this identity unless
 386    * authentication has happened.
 387    */
 388   struct ed25519_public_key_t ed25519_identity;
 389
 390   /**
 391    * Linked list of channels with the same RSA identity digest, for use with
 392    * the digest->channel map
 393    */
 394   TOR_LIST_ENTRY(channel_t) next_with_same_id;
 395
 396   /** Circuit mux for circuits sending on this channel */
 397   circuitmux_t *cmux;
 398
 399   /** Circuit ID generation stuff for use by circuitbuild.c */
 400
 401   /**
 402    * When we send CREATE cells along this connection, which half of the
 403    * space should we use?
 404    */
 405   circ_id_type_bitfield_t circ_id_type:2;
 406   /* DOCDOC */
 407   unsigned wide_circ_ids:1;
 408
 409   /** For how many circuits are we n_chan?  What about p_chan? */
 410   unsigned int num_n_circuits, num_p_circuits;
 411
 412   /**
 413    * True iff this channel shouldn't get any new circs attached to it,
 414    * because the connection is too old, or because there's a better one.
 415    * More generally, this flag is used to note an unhealthy connection;
 416    * for example, if a bad connection fails we shouldn't assume that the
 417    * router itself has a problem.
 418    */
 419   unsigned int is_bad_for_new_circs:1;
 420
 421   /** True iff we have decided that the other end of this connection
 422    * is a client or bridge relay.  Connections with this flag set should never
 423    * be used to satisfy an EXTEND request. */
 424   unsigned int is_client:1;
 425
 426   /** Set if the channel was initiated remotely (came from a listener) */
 427   unsigned int is_incoming:1;
 428
 429   /** Set by lower layer if this is local; i.e., everything it communicates
 430    * with for this channel returns true for is_local_addr().  This is used
 431    * to decide whether to declare reachability when we receive something on
 432    * this channel in circuitbuild.c
 433    */
 434   unsigned int is_local:1;
 435
 436   /** Have we logged a warning about circID exhaustion on this channel?
 437    * If so, when? */
 438   ratelim_t last_warned_circ_ids_exhausted;
 439
 440   /** Channel timestamps for cell channels */
 441   time_t timestamp_client; /*(< Client used this, according to relay.c */
 442   time_t timestamp_recv; /**< Cell received from lower layer */
 443   time_t timestamp_xmit; /**< Cell sent to lower layer */
 444
 445   /** Timestamp for run_connection_housekeeping(). We update this once a
 446    * second when we run housekeeping and find a circuit on this channel, and
 447    * whenever we add a circuit to the channel. */
 448   time_t timestamp_last_had_circuits;
 449
 450   /** Unique ID for measuring direct network status requests;vtunneled ones
 451    * come over a circuit_t, which has a dirreq_id field as well, but is a
 452    * distinct namespace. */
 453   uint64_t dirreq_id;
 454
 455   /** Channel counters for cells and bytes we have received. */
 456   uint64_t n_cells_recved, n_bytes_recved;
 457   /** Channel counters for cells and bytes we have sent. */
 458   uint64_t n_cells_xmitted, n_bytes_xmitted;
 459 };
 460
 461 struct channel_listener_t {
 462   /** Current channel listener state */
 463   channel_listener_state_t state;
 464
 465   /** Globally unique ID number for a channel over the lifetime of a Tor
 466    * process.
 467    */
 468   uint64_t global_identifier;
 469
 470   /** Should we expect to see this channel in the channel lists? */
 471   unsigned char registered:1;
 472
 473   /** Why did we close?
 474    */
 475   enum {
 476     CHANNEL_LISTENER_NOT_CLOSING = 0,
 477     CHANNEL_LISTENER_CLOSE_REQUESTED,
 478     CHANNEL_LISTENER_CLOSE_FROM_BELOW,
 479     CHANNEL_LISTENER_CLOSE_FOR_ERROR
 480   } reason_for_closing;
 481
 482   /** Timestamps for both cell channels and listeners */
 483   time_t timestamp_created; /* Channel created */
 484   time_t timestamp_active; /* Any activity */
 485
 486   /* Methods implemented by the lower layer */
 487
 488   /** Free a channel */
 489   void (*free_fn)(channel_listener_t *);
 490   /** Close an open channel */
 491   void (*close)(channel_listener_t *);
 492   /** Describe the transport subclass for this channel */
 493   const char * (*describe_transport)(channel_listener_t *);
 494   /** Optional method to dump transport-specific statistics on the channel */
 495   void (*dumpstats)(channel_listener_t *, int);
 496
 497   /** Registered listen handler to call on incoming connection */
 498   channel_listener_fn_ptr listener;
 499
 500   /** List of pending incoming connections */
 501   smartlist_t *incoming_list;
 502
 503   /** Timestamps for listeners */
 504   time_t timestamp_accepted;
 505
 506   /** Counters for listeners */
 507   uint64_t n_accepted;
 508 };
 509
 510 /* Channel state manipulations */
 511
 512 int channel_state_is_valid(channel_state_t state);
 513 int channel_listener_state_is_valid(channel_listener_state_t state);
 514
 515 int channel_state_can_transition(channel_state_t from, channel_state_t to);
 516 int channel_listener_state_can_transition(channel_listener_state_t from,
 517                                           channel_listener_state_t to);
 518
 519 const char * channel_state_to_string(channel_state_t state);
 520 const char *
 521 channel_listener_state_to_string(channel_listener_state_t state);
 522
 523 /* Abstract channel operations */
 524
 525 void channel_mark_for_close(channel_t *chan);
 526 int channel_write_packed_cell(channel_t *chan, packed_cell_t *cell);
 527
 528 void channel_listener_mark_for_close(channel_listener_t *chan_l);
 529 void channel_mark_as_used_for_origin_circuit(channel_t *chan);
 530
 531 /* Channel callback registrations */
 532
 533 /* Listener callback */
 534 void channel_listener_set_listener_fn(channel_listener_t *chan,
 535                                       channel_listener_fn_ptr listener);
 536
 537 /* Incoming cell callbacks */
 538 channel_cell_handler_fn_ptr channel_get_cell_handler(channel_t *chan);
 539
 540 void channel_set_cell_handlers(channel_t *chan,
 541                                channel_cell_handler_fn_ptr cell_handler);
 542
 543 /* Clean up closed channels and channel listeners periodically; these are
 544  * called from run_scheduled_events() in main.c.
 545  */
 546 void channel_run_cleanup(void);
 547 void channel_listener_run_cleanup(void);
 548
 549 /* Close all channels and deallocate everything */
 550 void channel_free_all(void);
 551
 552 /* Dump some statistics in the log */
 553 void channel_dumpstats(int severity);
 554 void channel_listener_dumpstats(int severity);
 555
 556 #ifdef CHANNEL_OBJECT_PRIVATE
 557
 558 #ifdef CHANNEL_FILE_PRIVATE
 559
 560 STATIC void channel_add_to_digest_map(channel_t *chan);
 561 STATIC bool channel_matches_target_addr_for_extend(
 562                                           channel_t *chan,
 563                                           const tor_addr_t *target_ipv4_addr,
 564                                           const tor_addr_t *target_ipv6_addr);
 565 #endif /* defined(CHANNEL_FILE_PRIVATE) */
 566
 567 /* Channel operations for subclasses and internal use only */
 568
 569 /* Initialize a newly allocated channel - do this first in subclass
 570  * constructors.
 571  */
 572
 573 void channel_init(channel_t *chan);
 574 void channel_init_listener(channel_listener_t *chan);
 575
 576 /* Channel registration/unregistration */
 577 void channel_register(channel_t *chan);
 578 void channel_unregister(channel_t *chan);
 579
 580 /* Channel listener registration/unregistration */
 581 void channel_listener_register(channel_listener_t *chan_l);
 582 void channel_listener_unregister(channel_listener_t *chan_l);
 583
 584 /* Close from below */
 585 void channel_close_from_lower_layer(channel_t *chan);
 586 void channel_close_for_error(channel_t *chan);
 587 void channel_closed(channel_t *chan);
 588
 589 /* Free a channel */
 590 void channel_free_(channel_t *chan);
 591 #define channel_free(chan) FREE_AND_NULL(channel_t, channel_free_, (chan))
 592 void channel_listener_free_(channel_listener_t *chan_l);
 593 #define channel_listener_free(chan_l) \
 594   FREE_AND_NULL(channel_listener_t, channel_listener_free_, (chan_l))
 595
 596 /* State/metadata setters */
 597
 598 void channel_change_state(channel_t *chan, channel_state_t to_state);
 599 void channel_change_state_open(channel_t *chan);
 600 void channel_clear_identity_digest(channel_t *chan);
 601 void channel_clear_remote_end(channel_t *chan);
 602 void channel_mark_local(channel_t *chan);
 603 void channel_mark_incoming(channel_t *chan);
 604 void channel_mark_outgoing(channel_t *chan);
 605 void channel_mark_remote(channel_t *chan);
 606 void channel_set_identity_digest(channel_t *chan,
 607                              const char *identity_digest,
 608                              const struct ed25519_public_key_t *ed_identity);
 609
 610 void channel_listener_change_state(channel_listener_t *chan_l,
 611                                    channel_listener_state_t to_state);
 612
 613 /* Timestamp updates */
 614 void channel_timestamp_created(channel_t *chan);
 615 void channel_timestamp_active(channel_t *chan);
 616 void channel_timestamp_recv(channel_t *chan);
 617 void channel_timestamp_xmit(channel_t *chan);
 618
 619 void channel_listener_timestamp_created(channel_listener_t *chan_l);
 620 void channel_listener_timestamp_active(channel_listener_t *chan_l);
 621 void channel_listener_timestamp_accepted(channel_listener_t *chan_l);
 622
 623 /* Incoming channel handling */
 624 void channel_listener_process_incoming(channel_listener_t *listener);
 625 void channel_listener_queue_incoming(channel_listener_t *listener,
 626                                      channel_t *incoming);
 627
 628 /* Incoming cell handling */
 629 void channel_process_cell(channel_t *chan, cell_t *cell);
 630
 631 /* Request from lower layer for more cells if available */
 632 MOCK_DECL(ssize_t, channel_flush_some_cells,
 633           (channel_t *chan, ssize_t num_cells));
 634
 635 /* Query if data available on this channel */
 636 MOCK_DECL(int, channel_more_to_flush, (channel_t *chan));
 637
 638 /* Notify flushed outgoing for dirreq handling */
 639 void channel_notify_flushed(channel_t *chan);
 640
 641 /* Handle stuff we need to do on open like notifying circuits */
 642 void channel_do_open_actions(channel_t *chan);
 643
 644 #endif /* defined(CHANNEL_OBJECT_PRIVATE) */
 645
 646 /* Helper functions to perform operations on channels */
 647
 648 int channel_send_destroy(circid_t circ_id, channel_t *chan,
 649                          int reason);
 650
 651 /*
 652  * Outside abstract interfaces that should eventually get turned into
 653  * something transport/address format independent.
 654  */
 655
 656 channel_t * channel_connect(const tor_addr_t *addr, uint16_t port,
 657                             const char *rsa_id_digest,
 658                             const struct ed25519_public_key_t *ed_id);
 659
 660 MOCK_DECL(channel_t *, channel_get_for_extend,(
 661                                    const char *rsa_id_digest,
 662                                    const struct ed25519_public_key_t *ed_id,
 663                                    const tor_addr_t *target_ipv4_addr,
 664                                    const tor_addr_t *target_ipv6_addr,
 665                                    bool for_origin_circ,
 666                                    const char **msg_out,
 667                                    int *launch_out));
 668
 669 /* Ask which of two channels is better for circuit-extension purposes */
 670 int channel_is_better(channel_t *a, channel_t *b);
 671
 672 /** Channel lookups
 673  */
 674
 675 channel_t * channel_find_by_global_id(uint64_t global_identifier);
 676 channel_t * channel_find_by_remote_identity(const char *rsa_id_digest,
 677                                     const struct ed25519_public_key_t *ed_id);
 678
 679 /** For things returned by channel_find_by_remote_digest(), walk the list.
 680  * The RSA key will match for all returned elements; the Ed25519 key might not.
 681  */
 682 channel_t * channel_next_with_rsa_identity(channel_t *chan);
 683
 684 /*
 685  * Helper macros to lookup state of given channel.
 686  */
 687
 688 #define CHANNEL_IS_CLOSED(chan) (channel_is_in_state((chan), \
 689                                  CHANNEL_STATE_CLOSED))
 690 #define CHANNEL_IS_OPENING(chan) (channel_is_in_state((chan), \
 691                                   CHANNEL_STATE_OPENING))
 692 #define CHANNEL_IS_OPEN(chan) (channel_is_in_state((chan), \
 693                                CHANNEL_STATE_OPEN))
 694 #define CHANNEL_IS_MAINT(chan) (channel_is_in_state((chan), \
 695                                 CHANNEL_STATE_MAINT))
 696 #define CHANNEL_IS_CLOSING(chan) (channel_is_in_state((chan), \
 697                                   CHANNEL_STATE_CLOSING))
 698 #define CHANNEL_IS_ERROR(chan) (channel_is_in_state((chan), \
 699                                 CHANNEL_STATE_ERROR))
 700
 701 #define CHANNEL_FINISHED(chan) (CHANNEL_IS_CLOSED(chan) || \
 702                                 CHANNEL_IS_ERROR(chan))
 703
 704 #define CHANNEL_CONDEMNED(chan) (CHANNEL_IS_CLOSING(chan) || \
 705                                  CHANNEL_FINISHED(chan))
 706
 707 #define CHANNEL_CAN_HANDLE_CELLS(chan) (CHANNEL_IS_OPENING(chan) || \
 708                                         CHANNEL_IS_OPEN(chan) || \
 709                                         CHANNEL_IS_MAINT(chan))
 710
 711 static inline int
 712 channel_is_in_state(channel_t *chan, channel_state_t state)
 713 {
 714   return chan->state == state;
 715 }
 716
 717 /*
 718  * Metadata queries/updates
 719  */
 720
 721 const char * channel_describe_transport(channel_t *chan);
 722 MOCK_DECL(void, channel_dump_statistics, (channel_t *chan, int severity));
 723 void channel_dump_transport_statistics(channel_t *chan, int severity);
 724 MOCK_DECL(int, channel_get_addr_if_possible, (const channel_t *chan,
 725                                               tor_addr_t *addr_out));
 726 MOCK_DECL(const char *, channel_describe_peer,(channel_t *chan));
 727 int channel_has_queued_writes(channel_t *chan);
 728 int channel_is_bad_for_new_circs(channel_t *chan);
 729 void channel_mark_bad_for_new_circs(channel_t *chan);
 730 int channel_is_canonical(channel_t *chan);
 731 int channel_is_client(const channel_t *chan);
 732 int channel_is_local(channel_t *chan);
 733 int channel_is_incoming(channel_t *chan);
 734 int channel_is_outgoing(channel_t *chan);
 735 void channel_mark_client(channel_t *chan);
 736 void channel_clear_client(channel_t *chan);
 737 int channel_matches_extend_info(channel_t *chan, extend_info_t *extend_info);
 738 int channel_remote_identity_matches(const channel_t *chan,
 739                                     const char *rsa_id_digest,
 740                                     const ed25519_public_key_t *ed_id);
 741 unsigned int channel_num_circuits(channel_t *chan);
 742 MOCK_DECL(void,channel_set_circid_type,(channel_t *chan,
 743                                         crypto_pk_t *identity_rcvd,
 744                                         int consider_identity));
 745 void channel_timestamp_client(channel_t *chan);
 746
 747 const char * channel_listener_describe_transport(channel_listener_t *chan_l);
 748 void channel_listener_dump_statistics(channel_listener_t *chan_l,
 749                                       int severity);
 750 void channel_listener_dump_transport_statistics(channel_listener_t *chan_l,
 751                                                 int severity);
 752 void channel_check_for_duplicates(void);
 753
 754 void channel_update_bad_for_new_circs(const char *digest, int force);
 755
 756 /* Flow control queries */
 757 int channel_num_cells_writeable(channel_t *chan);
 758
 759 /* Timestamp queries */
 760 time_t channel_when_created(channel_t *chan);
 761 time_t channel_when_last_client(channel_t *chan);
 762 time_t channel_when_last_xmit(channel_t *chan);
 763
 764 /* Counter queries */
 765 int packed_cell_is_destroy(channel_t *chan,
 766                            const packed_cell_t *packed_cell,
 767                            circid_t *circid_out);
 768
 769 /* Declare the handle helpers */
 770 HANDLE_DECL(channel, channel_t,)
 771 #define channel_handle_free(h)    \
 772   FREE_AND_NULL(channel_handle_t, channel_handle_free_, (h))
 773 #undef tor_timer_t
 774
 775 #endif /* !defined(TOR_CHANNEL_H) */