text: /* Copyright (c) 2001 Matej Pfajfar.
   * Copyright (c) 2001-2004, Roger Dingledine.
   * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
   * Copyright (c) 2007-2016, The Tor Project, Inc. */
  /* See LICENSE for licensing information */
  
  /**
   * \file buffers.h
   * \brief Header file for buffers.c.
   **/
  
  #ifndef TOR_BUFFERS_H
  #define TOR_BUFFERS_H
  
  #include "testsupport.h"
  
  buf_t *buf_new(void);
  buf_t *buf_new_with_capacity(size_t size);
  size_t buf_get_default_chunk_size(const buf_t *buf);
  void buf_free(buf_t *buf);
  void buf_clear(buf_t *buf);
  char* buf_read_header(buf_t *buf);
  buf_t *buf_copy(const buf_t *buf);
  
  MOCK_DECL(size_t, buf_datalen, (const buf_t *buf));
  size_t buf_allocation(const buf_t *buf);
  size_t buf_slack(const buf_t *buf);
  
  uint32_t buf_get_oldest_chunk_timestamp(const buf_t *buf, uint32_t now);
  size_t buf_get_total_allocation(void);
  
  int read_to_buf(tor_socket_t s, size_t at_most, buf_t *buf, int *reached_eof,
                  int *socket_error);
  int read_to_buf_tls(tor_tls_t *tls, size_t at_most, buf_t *buf);
  
  int flush_buf(tor_socket_t s, buf_t *buf, size_t sz, size_t *buf_flushlen);
  int flush_buf_tls(tor_tls_t *tls, buf_t *buf, size_t sz, size_t *buf_flushlen);
  
  int write_to_buf(const char *string, size_t string_len, buf_t *buf);
  int write_to_buf_zlib(buf_t *buf, tor_zlib_state_t *state,
                        const char *data, size_t data_len, int done);
  int move_buf_to_buf(buf_t *buf_out, buf_t *buf_in, size_t *buf_flushlen);
  int fetch_from_buf(char *string, size_t string_len, buf_t *buf);
  int fetch_var_cell_from_buf(buf_t *buf, var_cell_t **out, int linkproto);
  int fetch_from_buf_http(buf_t *buf,
                          char **headers_out, size_t max_headerlen,
                          char **body_out, size_t *body_used, size_t max_bodylen,
                          int force_complete);
  socks_request_t *socks_request_new(void);
  void socks_request_free(socks_request_t *req);
  int fetch_from_buf_socks(buf_t *buf, socks_request_t *req,
                           int log_sockstype, int safe_socks);
  int fetch_from_buf_socks_client(buf_t *buf, int state, char **reason);
  int fetch_from_buf_line(buf_t *buf, char *data_out, size_t *data_len);
  
  int peek_buf_has_control0_command(buf_t *buf);
  
  int fetch_ext_or_command_from_buf(buf_t *buf, ext_or_cmd_t **out);
  
  #ifdef USE_BUFFEREVENTS
  int fetch_var_cell_from_evbuffer(struct evbuffer *buf, var_cell_t **out,
                                   int linkproto);
  int fetch_from_evbuffer_socks(struct evbuffer *buf, socks_request_t *req,
                                int log_sockstype, int safe_socks);
  int fetch_from_evbuffer_socks_client(struct evbuffer *buf, int state,
                                       char **reason);
  int fetch_from_evbuffer_http(struct evbuffer *buf,
                          char **headers_out, size_t max_headerlen,
                          char **body_out, size_t *body_used, size_t max_bodylen,
                          int force_complete);
  int peek_evbuffer_has_control0_command(struct evbuffer *buf);
  int write_to_evbuffer_zlib(struct evbuffer *buf, tor_zlib_state_t *state,
                             const char *data, size_t data_len,
                             int done);
  int fetch_ext_or_command_from_evbuffer(struct evbuffer *buf,
                                         ext_or_cmd_t **out);
  #endif
  
  #ifdef USE_BUFFEREVENTS
  #define generic_buffer_new() evbuffer_new()
  #define generic_buffer_len(b) evbuffer_get_length((b))
  #define generic_buffer_add(b,dat,len) evbuffer_add((b),(dat),(len))
  #define generic_buffer_get(b,buf,buflen) evbuffer_remove((b),(buf),(buflen))
  #define generic_buffer_clear(b) evbuffer_drain((b), evbuffer_get_length((b)))
  #define generic_buffer_free(b) evbuffer_free((b))
  #define generic_buffer_fetch_ext_or_cmd(b, out) \
    fetch_ext_or_command_from_evbuffer((b), (out))
  #else
  #define generic_buffer_new() buf_new()
  #define generic_buffer_len(b) buf_datalen((b))
  #define generic_buffer_add(b,dat,len) write_to_buf((dat),(len),(b))
  #define generic_buffer_get(b,buf,buflen) fetch_from_buf((buf),(buflen),(b))
  #define generic_buffer_clear(b) buf_clear((b))
  #define generic_buffer_free(b) buf_free((b))
  #define generic_buffer_fetch_ext_or_cmd(b, out) \
    fetch_ext_or_command_from_buf((b), (out))
  #endif
  int generic_buffer_set_to_copy(generic_buffer_t **output,
                                 const generic_buffer_t *input);
  
  void assert_buf_ok(buf_t *buf);
  
  #ifdef BUFFERS_PRIVATE
  STATIC int buf_find_string_offset(const buf_t *buf, const char *s, size_t n);
  STATIC void buf_pullup(buf_t *buf, size_t bytes);
  void buf_get_first_chunk_data(const buf_t *buf, const char **cp, size_t *sz);
  
  #define DEBUG_CHUNK_ALLOC
  /** A single chunk on a buffer. */
  typedef struct chunk_t {
    struct chunk_t *next; /**< The next chunk on the buffer. */
    size_t datalen; /**< The number of bytes stored in this chunk */
    size_t memlen; /**< The number of usable bytes of storage in <b>mem</b>. */
  #ifdef DEBUG_CHUNK_ALLOC
    size_t DBG_alloc;
  #endif
    char *data; /**< A pointer to the first byte of data stored in <b>mem</b>. */
    uint32_t inserted_time; /**< Timestamp in truncated ms since epoch
                             * when this chunk was inserted. */
    char mem[FLEXIBLE_ARRAY_MEMBER]; /**< The actual memory used for storage in
                  * this chunk. */
  } chunk_t;
  
  /** Magic value for buf_t.magic, to catch pointer errors. */
  #define BUFFER_MAGIC 0xB0FFF312u
  /** A resizeable buffer, optimized for reading and writing. */
  struct buf_t {
    uint32_t magic; /**< Magic cookie for debugging: Must be set to
                     *   BUFFER_MAGIC. */
    size_t datalen; /**< How many bytes is this buffer holding right now? */
    size_t default_chunk_size; /**< Don't allocate any chunks smaller than
                                * this for this buffer. */
    chunk_t *head; /**< First chunk in the list, or NULL for none. */
    chunk_t *tail; /**< Last chunk in the list, or NULL for none. */
  };
  #endif
  
  #endif
  
  