Tor源码文件分析 -- Main_tor 源码分析-优快云博客

　　Main文件是Tor系统的主要执行函数所处文件，内容偏多，但是较于其他底层处理函数所在的文件，也算较少。所以这里做简要的分析，其中删去很多不常见的，不重要的函数，大家可以自行在源文件内部查看。

1. 全局变量

　　全局变量在文件头部定义，每个全局变量都已经有比较详尽的英文分析和解释，这里再做简单的罗列。

　　1）系统（先前）已读与已写字节数以及用于流量控制的令牌桶全局变量；（先前与当前已读写字节数的区别与refill回调函数相关）

　　令牌桶用于控制整个系统的流量，经过初始化，减少，增加等操作（当读写相应的令牌数不够时，系统或连接会停止读或写）：

// 初始化令牌桶令牌数
/** Initialize the global read bucket to options-\>BandwidthBurst. */
void
connection_bucket_init(void)
{
  const or_options_t *options = get_options();
  /* start it at max traffic */
  global_read_bucket = (int)options->BandwidthBurst;
  global_write_bucket = (int)options->BandwidthBurst;
  if (options->RelayBandwidthRate) {
    global_relayed_read_bucket = (int)options->RelayBandwidthBurst;
    global_relayed_write_bucket = (int)options->RelayBandwidthBurst;
  } else {
    global_relayed_read_bucket = (int)options->BandwidthBurst;
    global_relayed_write_bucket = (int)options->BandwidthBurst;
  }
}

// 减少令牌桶令牌数
/** We just read <b>num_read</b> and wrote <b>num_written</b> bytes
 * onto <b>conn</b>. Decrement buckets appropriately. */
static void
connection_buckets_decrement(connection_t *conn, time_t now,
                             size_t num_read, size_t num_written)
{
  ......

  if (connection_counts_as_relayed_traffic(conn, now)) {
    global_relayed_read_bucket -= (int)num_read;
    global_relayed_write_bucket -= (int)num_written;
  }
  global_read_bucket -= (int)num_read;
  global_write_bucket -= (int)num_written;

　......
}

// 增加令牌桶令牌数
/** Time has passed; increment buckets appropriately. */
void
connection_bucket_refill(int milliseconds_elapsed, time_t now)
{
  ......

  /* refill the global buckets */
  connection_bucket_refill_helper(&global_read_bucket,
                                  bandwidthrate, bandwidthburst,
                                  milliseconds_elapsed,
                                  "global_read_bucket");
  connection_bucket_refill_helper(&global_write_bucket,