HTTPDirFS - HTTP Directory Filesystem, with a permanent cache

Have you ever wanted to mount those HTTP directory listings as if it was a partition? Look no further, this is your solution. HTTPDirFS stands for Hyper Text Transfer Protocol Directory Filesystem.

The performance of the program is excellent. HTTP connections are reused due to the use of curl-multi interface. The FUSE component runs in multithreaded mode.

There is a permanent cache system which can cache all the file segments you have downloaded, so you don't need to these segments again if you access them later. This feature is triggered by the --cache flag. This makes this filesystem much faster than rclone mount.

Usage

./httpdirfs -f --cache -f $URL $YOUR_MOUNT_POINT

An example URL would be Debian CD Image Server. The -f flag keeps the program in the foreground, which is useful for monitoring which URL the filesystem is visiting.

Useful options

HTTPDirFS options:

-u  --username          HTTP authentication username
-p  --password          HTTP authentication password
-P  --proxy             Proxy for libcurl, for more details refer to
                        https://curl.haxx.se/libcurl/c/CURLOPT_PROXY.html
    --proxy-username    Username for the proxy
    --proxy-password    Password for the proxy
    --cache             Enable cache (default: off)
    --cache-location    Set a custom cache location
                        (default: "${XDG_CACHE_HOME}/httpdirfs")
    --dl-seg-size       Set cache download segment size, in MB (default: 8)
                        Note: this setting is ignored if previously
                        cached data is found for the requested file.
    --max-seg-count     Set maximum number of download segments a file
                        can have. (default: 128*1024)
                        With the default setting, the maximum memory usage
                        per file is 128KB. This allows caching files up
                        to 1TB in size using the default segment size.
    --max-conns         Set maximum number of network connections that
                        libcurl is allowed to make. (default: 10)
    --retry-wait        Set delay in seconds before retrying an HTTP request
                        after encountering an error. (default: 5)
    --user-agent        Set user agent string (default: "HTTPDirFS")

FUSE options:

-d   -o debug          enable debug output (implies -f)
-f                     foreground operation
-s                     disable multi-threaded operation

Permanent cache system

You can cache all the files you have looked at permanently on your hard drive by using the --cache flag. The file it caches persist across sessions.

By default, the cache files are stored under ${XDG_CACHE_HOME}/httpdirfs, which by default is ${HOME}/.cache/httpdirfs. Each HTTP directory gets its own cache folder, they are named using the escaped URL of the HTTP directory.

Once a segment of the file has been downloaded once, it won't be downloaded again.

Please note that due to the way the permanent cache system is implemented. The maximum download speed is around 15MiB/s, as measured using my localhost as the web server. However after you have accessed a file once, accessing it again will be the same speed as accessing your hard drive.

If you have any patches to make the initial download go faster, please submit a pull request.

The permanent cache system relies on sparse allocation. Please make sure your filesystem supports it. Otherwise your hard drive / SSD will get heavy I/O from cache file creation. For a list of filesystem that supports sparse allocation, please refer to Wikipedia.

Configuration file support

This program has basic support for using a configuration file. The configuration file that the program reads is ${XDG_CONFIG_HOME}/httpdirfs/config, which by default is at ${HOME}/.config/httpdirfs/config. You will have to create the sub-directory and the configuration file yourself. In the configuration file, please supply one option per line. For example:

--username test
--password test
-f

Compilation

Debian 10 "Buster" and newer versions

Under Debian 10 "Buster" and newer versions, you need the following packages:

libgumbo-dev libfuse-dev libssl-dev libcurl4-openssl-dev

Debian 9 "Stretch"

Under Debian 9 "Stretch", you need the following packages:

libgumbo-dev libfuse-dev libssl1.0-dev libcurl4-openssl-dev

If you get the following warnings during compilation,

/usr/bin/ld: warning: libcrypto.so.1.0.2, needed by /usr/lib/gcc/x86_64-linux-gnu/6/../../../x86_64-linux-gnu/libcurl.so, may conflict with libcrypto.so.1.1

then this program will crash if you connect to HTTPS website. You need to check if you have libssl1.0-dev installed rather than libssl-dev. This is you likely have the binaries of OpenSSL 1.0.2 installed alongside with the header files for OpenSSL 1.1. The header files for OpenSSL 1.0.2 link in additional mutex related callback functions, whereas the header files for OpenSSL 1.1 do not.

Debugging Mutexes

By default the debugging output associated with mutexes are not compiled. To enable them, compile the program with the -DCACHE_LOCK_DEBUG, the -DNETWORK_LOCK_DEBUG and/or the -DLINK_LOCK_DEBUG CPPFLAGS, e.g.

make CPPFLAGS=-DCACHE_LOCK_DEBUG

The Technical Details

This program downloads the HTML web pages/files using libcurl, then parses the listing pages using Gumbo, and presents them using libfuse.

The cache system stores the metadata and the downloaded file into two separate directories. It uses uint8_t arrays to record which segments of the file had been downloaded.

Other projects which incorporate HTTPDirFS

• Curious Container has a Python wrapper for mounting HTTPDirFS.

Acknowledgement

• First of all, I would like to thank Jerome Charaoui for being the Debian Maintainer for this piece of software. Thank you so much for packaging it!
• I would like to thank Cosmin Gorgovan for the technical and moral support. Your wisdom is much appreciated!
• I would like to thank -Archivist for not providing FTP or WebDAV access to his server. This piece of software was written in direct response to his appalling behaviour.