or.h

关于tor匿名通信的源代码

/** Length of 'y' portion of 'y.onion' URL. */
#define REND_SERVICE_ID_LEN_BASE32 16

/** Length of a binary-encoded rendezvous service ID. */
#define REND_SERVICE_ID_LEN 10

/** Time period for which a v2 descriptor will be valid. */
#define REND_TIME_PERIOD_V2_DESC_VALIDITY (24*60*60)

/** Time period within which two sets of v2 descriptors will be uploaded in
 * parallel. */
#define REND_TIME_PERIOD_OVERLAPPING_V2_DESCS (60*60)

/** Number of non-consecutive replicas (i.e. distributed somewhere
 * in the ring) for a descriptor. */
#define REND_NUMBER_OF_NON_CONSECUTIVE_REPLICAS 2

/** Number of consecutive replicas for a descriptor. */
#define REND_NUMBER_OF_CONSECUTIVE_REPLICAS 3

/** Length of v2 descriptor ID (32 base32 chars = 160 bits). */
#define REND_DESC_ID_V2_LEN_BASE32 32

/** Length of the base32-encoded secret ID part of versioned hidden service
 * descriptors. */
#define REND_SECRET_ID_PART_LEN_BASE32 32

/** Length of the base32-encoded hash of an introduction point's
 * identity key. */
#define REND_INTRO_POINT_ID_LEN_BASE32 32

#define CELL_DIRECTION_IN 1
#define CELL_DIRECTION_OUT 2

/** Initial value for both sides of a circuit transmission window when the
 * circuit is initialized.  Measured in cells. */
#define CIRCWINDOW_START 1000
/** Amount to increment a circuit window when we get a circuit SENDME. */
#define CIRCWINDOW_INCREMENT 100
/** Initial value on both sides of a stream transmission window when the
 * stream is initialized.  Measured in cells. */
#define STREAMWINDOW_START 500
/** Amount to increment a stream window when we get a stream SENDME. */
#define STREAMWINDOW_INCREMENT 50

/* cell commands */
#define CELL_PADDING 0
#define CELL_CREATE 1
#define CELL_CREATED 2
#define CELL_RELAY 3
#define CELL_DESTROY 4
#define CELL_CREATE_FAST 5
#define CELL_CREATED_FAST 6
#define CELL_VERSIONS 7
#define CELL_NETINFO 8
#define CELL_RELAY_EARLY 9

#define CELL_COMMAND_IS_VAR_LENGTH(x) ((x) == CELL_VERSIONS)

/** How long to test reachability before complaining to the user. */
#define TIMEOUT_UNTIL_UNREACHABILITY_COMPLAINT (20*60)

/** Legal characters in a nickname. */
#define LEGAL_NICKNAME_CHARACTERS \
  "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"

/** Name to use in client TLS certificates if no nickname is given. */
#define DEFAULT_CLIENT_NICKNAME "client"

/** Number of bytes in a SOCKS4 header. */
#define SOCKS4_NETWORK_LEN 8

/** Specified SOCKS5 status codes. */
typedef enum {
  SOCKS5_SUCCEEDED                  = 0x00,
  SOCKS5_GENERAL_ERROR              = 0x01,
  SOCKS5_NOT_ALLOWED                = 0x02,
  SOCKS5_NET_UNREACHABLE            = 0x03,
  SOCKS5_HOST_UNREACHABLE           = 0x04,
  SOCKS5_CONNECTION_REFUSED         = 0x05,
  SOCKS5_TTL_EXPIRED                = 0x06,
  SOCKS5_COMMAND_NOT_SUPPORTED      = 0x07,
  SOCKS5_ADDRESS_TYPE_NOT_SUPPORTED = 0x08,
} socks5_reply_status_t;

/*
 * Relay payload:
 *         Relay command           [1 byte]
 *         Recognized              [2 bytes]
 *         Stream ID               [2 bytes]
 *         Partial SHA-1           [4 bytes]
 *         Length                  [2 bytes]
 *         Relay payload           [498 bytes]
 */

/** Number of bytes in a cell, minus cell header. */
#define CELL_PAYLOAD_SIZE 509
/** Number of bytes in a cell transmitted over the network. */
#define CELL_NETWORK_SIZE 512

#define VAR_CELL_HEADER_SIZE 5

/** Number of bytes in a relay cell's header (not including general cell
 * header). */
#define RELAY_HEADER_SIZE (1+2+2+4+2)
/** Largest number of bytes that can fit in a relay cell payload. */
#define RELAY_PAYLOAD_SIZE (CELL_PAYLOAD_SIZE-RELAY_HEADER_SIZE)

/** Parsed onion routing cell.  All communication between nodes
 * is via cells. */
typedef struct cell_t {
  uint16_t circ_id; /**< Circuit which received the cell. */
  uint8_t command; /**< Type of the cell: one of CELL_PADDING, CELL_CREATE,
                    * CELL_DESTROY, etc */
  char payload[CELL_PAYLOAD_SIZE]; /**< Cell body. */
} cell_t;

/** Parsed variable-length onion routing cell. */
typedef struct var_cell_t {
  uint8_t command;
  uint16_t circ_id;
  uint16_t payload_len;
  char payload[1];
} var_cell_t;

/** A cell as packed for writing to the network. */
typedef struct packed_cell_t {
  struct packed_cell_t *next; /**< Next cell queued on this circuit. */
  char body[CELL_NETWORK_SIZE]; /**< Cell as packed for network. */
} packed_cell_t;

/** A queue of cells on a circuit, waiting to be added to the
 * or_connection_t's outbuf. */
typedef struct cell_queue_t {
  packed_cell_t *head; /**< The first cell, or NULL if the queue is empty. */
  packed_cell_t *tail; /**< The last cell, or NULL if the queue is empty. */
  int n; /**< The number of cells in the queue. */
} cell_queue_t;

/** Beginning of a RELAY cell payload. */
typedef struct {
  uint8_t command; /**< The end-to-end relay command. */
  uint16_t recognized; /**< Used to tell whether cell is for us. */
  uint16_t stream_id; /**< Which stream is this cell associated with? */
  char integrity[4]; /**< Used to tell whether cell is corrupted. */
  uint16_t length; /**< How long is the payload body? */
} relay_header_t;

typedef struct buf_t buf_t;
typedef struct socks_request_t socks_request_t;

/* Values for connection_t.magic: used to make sure that downcasts (casts from
* connection_t to foo_connection_t) are safe. */
#define BASE_CONNECTION_MAGIC 0x7C3C304Eu
#define OR_CONNECTION_MAGIC 0x7D31FF03u
#define EDGE_CONNECTION_MAGIC 0xF0374013u
#define DIR_CONNECTION_MAGIC 0x9988ffeeu
#define CONTROL_CONNECTION_MAGIC 0x8abc765du

/** Description of a connection to another host or process, and associated
 * data.
 *
 * A connection is named based on what it's connected to -- an "OR
 * connection" has a Tor node on the other end, an "exit
 * connection" has a website or other server on the other end, and an
 * "AP connection" has an application proxy (and thus a user) on the
 * other end.
 *
 * Every connection has a type and a state.  Connections never change
 * their type, but can go through many state changes in their lifetime.
 *
 * Every connection has two associated input and output buffers.
 * Listeners don't use them.  For non-listener connections, incoming
 * data is appended to conn->inbuf, and outgoing data is taken from
 * conn->outbuf.  Connections differ primarily in the functions called
 * to fill and drain these buffers.
 */
typedef struct connection_t {
  uint32_t magic; /**< For memory debugging: must equal one of
                   * *_CONNECTION_MAGIC. */

  uint8_t state; /**< Current state of this connection. */
  unsigned int type:4; /**< What kind of connection is this? */
  unsigned int purpose:5; /**< Only used for DIR and EXIT types currently. */

  /* The next fields are all one-bit booleans. Some are only applicable to
   * connection subtypes, but we hold them here anyway, to save space.
   */
  unsigned int read_blocked_on_bw:1; /**< Boolean: should we start reading
                            * again once the bandwidth throttler allows it? */
  unsigned int write_blocked_on_bw:1; /**< Boolean: should we start writing
                             * again once the bandwidth throttler allows
                             * reads? */
  unsigned int hold_open_until_flushed:1; /**< Despite this connection's being
                                      * marked for close, do we flush it
                                      * before closing it? */
  unsigned int inbuf_reached_eof:1; /**< Boolean: did read() return 0 on this
                                     * conn? */
  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().
                         */
  /** Edge connections only: true if we've blocked reading until the
   * circuit has fewer queued cells. */
  unsigned int edge_blocked_on_circ:1;
  /** Used for OR conns that shouldn't get any new circs attached to them. */
  unsigned int or_is_obsolete:1;
  /** For AP connections only. If 1, and we fail to reach the chosen exit,
   * stop requiring it. */
  unsigned int chosen_exit_optional:1;
  /** For AP connections only. If non-zero, this exit node was picked as
   * a result of the TrackHostExit, and the value decrements every time
   * we fail to complete a circuit to our chosen exit -- if it reaches
   * zero, abandon the associated mapaddress. */
  unsigned int chosen_exit_retries:3;
  /** Set to 1 when we're inside connection_flushed_some to keep us from
   * calling connection_handle_write() recursively. */
  unsigned int in_flushed_some:1;

  /* For linked connections:
   */
  unsigned int linked:1; /**< True if there is, or has been, a linked_conn. */
  /** True iff we'd like to be notified about read events from the
   * linked conn. */
  unsigned int reading_from_linked_conn:1;
  /** True iff we're willing to write to the linked conn. */
  unsigned int writing_to_linked_conn:1;
  /** True iff we're currently able to read on the linked conn, and our
   * read_event should be made active with libevent. */
  unsigned int active_on_link:1;
  /** True iff we've called connection_close_immediate() on this linked
   * connection. */
  unsigned int linked_conn_is_closed:1;

  int s; /**< Our socket; -1 if this connection is closed, or has no
          * socket. */
  int conn_array_index; /**< Index into the global connection array. */
  struct event *read_event; /**< Libevent event structure. */
  struct event *write_event; /**< Libevent event structure. */
  buf_t *inbuf; /**< Buffer holding data read over this connection. */
  buf_t *outbuf; /**< Buffer holding data to write over this connection. */
  size_t outbuf_flushlen; /**< How much data should we try to flush from the
                           * outbuf? */
  time_t timestamp_lastread; /**< When was the last time libevent said we could
                              * read? */
  time_t timestamp_lastwritten; /**< When was the last time libevent said we
                                 * could write? */
  time_t timestamp_created; /**< When was this connection_t created? */

  /* XXXX_IP6 make this ipv6-capable */
  int socket_family; /**< Address family of this connection's socket.  Usually
                      * AF_INET, but it can also be AF_UNIX, or in the future
                      * AF_INET6 */
  uint32_t addr; /**< IP of the other side of the connection; used to identify
                  * routers, along with port. */
  uint16_t port; /**< If non-zero, port  on the other end
                  * of the connection. */
  uint16_t marked_for_close; /**< Should we close this conn on the next
                              * iteration of the main loop? (If true, holds
                              * the line number where this connection was
                              * marked.) */
  const char *marked_for_close_file; /**< For debugging: in which file were
                                      * we marked for close? */
  char *address; /**< FQDN (or IP) of the guy on the other end.
                  * strdup into this, because free_connection frees it. */
  /** Another connection that's connected to this one in lieu of a socket. */
  struct connection_t *linked_conn;

  /* XXXX021 move this into a subtype. */
  struct evdns_server_port *dns_server_port;

} connection_t;

/** Stores flags and information related to the portion of a v2 Tor OR
 * connection handshake that happens after the TLS handshake is finished.
 */
typedef struct or_handshake_state_t {
  /** When was the VERSIONS cell sent on this connection?  Used to get
   * an estimate of the skew in the returning NETINFO reply. */
  time_t sent_versions_at;
  /** True iff we originated this connection */
  unsigned int started_here : 1;
  /** True iff we have received and processed a VERSIONS cell. */
  unsigned int received_versions : 1;
} or_handshake_state_t;

/** Subtype of connection_t for an "OR connection" -- that is, one that speaks
 * cells over TLS. */
typedef struct or_connection_t {
  connection_t _base;

  /** Hash of the public RSA key for the other side's identity key, or zeroes
   * if the other side hasn't shown us a valid identity key. */
  char identity_digest[DIGEST_LEN];
  char *nickname; /**< Nickname of OR on other side (if any). */

  tor_tls_t *tls; /**< TLS connection state. */
  int tls_error; /**< Last tor_tls error code. */
  /** When we last used this conn for any client traffic. If not
   * recent, we can rate limit it further. */