What file is a torrent?

Torrent is a BT seed file, which is essentially a text file; the torrent file contains two parts: Tracker information and file information. Tracker information is mainly the address of the Tracker server that needs to be used in BT downloads and the address of the Tracker server. Settings, file information is generated based on calculations on the target file, and the calculation results are encoded according to the B encoding rules within the BitTorrent protocol.

The operating environment of this tutorial: Windows 10 system, DELL G3 computer.

What is a torrent file?

Torrent is the suffix name of BT seed file, which is a kind of computer file

A torrent file is essentially a text file , including Tracker information and file information. Tracker information is mainly the address of the Tracker server and the settings for the Tracker server that need to be used in BT downloads. The file information is generated based on the calculation of the target file, and the calculation results are encoded according to the B encoding rules in the BitTorrent protocol. Therefore, the torrent file is the "index" of the downloaded file.

Brief introduction

The torrent file (extension .torrent) contains some information necessary for BT downloading:

The name of the resource. If the resource is in the form of a directory, there is also the path information and file name of each file in the directory tree.

If the resource is a single file, the size information of this file; if it is in the form of a directory, the size of each file in the directory tree.

A collection of several characteristic values ​​obtained by dividing the actual file of the resource into blocks according to a fixed size and performing SHA1 hash operation on each block.

The creation time of the torrent file, the comments filled in by the producer, and the producer’s information, etc.

At least one announce address, corresponding to a Tracker server deployed on the Internet.

With this file, you can download the latest and coolest stuff. Torrent files are usually very small, about tens or hundreds of K in size.

According to the BitTorrent protocol, the file publisher will generate and provide a .torrent file based on the file to be published, that is, a seed file, also referred to as a "seed".

Function:

According to the BitTorrent protocol, the file publisher will generate and provide a seed file based on the file to be published. To download the file content, the downloader needs to first obtain the corresponding seed file, and then use BT client software to download.

When downloading, the BT client first parses the seed file to obtain the Tracker address, and then connects to the Tracker server.

Every time the downloader gets a block, he needs to calculate the Hash verification code of the downloaded block and compare it with the seed file. If they are the same, it means that the block is correct. If they are not the same, the block needs to be downloaded again. This provision is to address the issue of accuracy of downloaded content.

In order to solve the problem of some users "running away after downloading", there is also a super seed algorithm in the unofficial BitTorrent protocol.

Function:

A torrent file is essentially a text file, containing Tracker information and file information. Tracker information is mainly the address of the Tracker server and the settings for the Tracker server that need to be used in BT downloads. The file information is generated based on the calculation of the target file, and the calculation results are encoded according to the B encoding rules in the BitTorrent protocol. Its main principle is to virtually divide the files provided for download into equal-sized blocks. The block size must be an integer power of 2k (due to virtual blocking, individual block files are not generated on the hard disk), and each block is The index information and Hash verification code are written into the .torrent file; therefore, the .torrent file is the "index" of the downloaded file.

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