2 unstable releases

0.4.0 Nov 23, 2022
0.2.0 Jun 3, 2022

#9 in #cgi

GPL-3.0-or-later

51KB
1K SLoC

Contents

Description

Agis will be a Spartan protocol server written in Rust. It is currently under active development but is not yet functional.

Building

Agis is written in Rust and requires the Cargo build tool.

# Build a release binary
cargo build --release

Features

  • Multithreaded worker pool
  • Static files
  • Virtual hosts (name based)
  • CGI
  • CGI ScriptAlias
  • Redirects
  • Aliases
  • indexes

Configuration

The configuration file is in Ron format, which should be very simple to grasp if you are used to any programming languages with braces (such as C). There is an example config file with plenty of comments in conf/config.ron. This file can be copied to /etc/agis/config.ron and edited to match your actual desired configuration.

Fields (Global)

  • address
    • ip - The ip address to bind to
    • port - The port to listen on. Spartan specifies port 300, so only change this if you have a specific use case for it.
  • address1 - An optional second ip address, useful for example to run both ipv4 and ipv6 simultaneously. If not needed, can be omitted entirely.
    • ip - as above
    • port - as above
  • user - The user which this server will run as. Agis must be started as root in order to bind to one of the lower ports, but will drop priviledges as soon as it is initialized.
  • group - The group which the server will run as.
  • threads - The number of threads to be started to handle requests. It is unlikely that you will have enough traffic to warrant increasing this.
  • access_log - If this is set to None, access will be logged to stdout. If it is set to Some(path) access will be logged to that file.
  • error_log - See access_log for specifics. Logs errors either to stderr or file.
  • vhosts - One or more name based virtual hosts.

Fields (per Vhost)

Each vhost is looked up by a key, which is the domain name it will serve.

  • name - The domain name for which to serve requests.
  • root - The path to the root directory of this server's files.
  • directories - Path specific directives.

Directives

Each directive is looked up via a key, which is the path which it applies to.

  • Allow(bool) - whether or not to allow access to this path. If not set, all files in the document tree under the server root are allowed. If set to false, all files under this path are disallowed.
  • Alias(path) - Serves files requested for this path from a different path. This is handled by the server transparently to the client.
  • Redirect - Any request for this specific path will be sent a redirect to the new location, to be handled by the client.
  • Cgi - Any requests under this directory will be passed to the cgi program which is the direct child of the directory. If the Cgi directive is given the path '/cgi-bin/', and a client requests '/cgi-bin/foo/bar/baz.gmi?fizzbuzz=true' then the program located at '/server-root/cgi-bin/foo' will be run and given the rest of the path and query as environment variables. This implementation is a subset of CGI 1.1 with http specific environment vars removed.
  • ScriptAlias(path) - Any requests under this path will be interpreted via the CGI program specified by . The is given as an absolute path, with the path to the server root stripped from it. Thus, if the server root is /srv/spartan and the CGI program resides at /srv/spartan/cgi-bin/hello, then would be given as /cgi-bin/hello.

The default configuration runs the server as user 'agis' and group 'agis'. You will need to create that user and group on your system or Agis will not run.

useradd -r -s /sbin/nologin agis

Running

If you are running Linux with Systemd init, there is a unit file included in the conf/ subdirectory. It can be copied into /etc/systemd/system and then started and stopped like any other service.

If you are on a Linux system that does not use systemd, or bsd, it should be straitforward to write your own init script. The default location for the configuration file is /etc/agis/config.ron but can be overridden on the command line with the -c or --config flag. This is currently the only command line option which is supported, making startup quite straightforward.

CGI

A CGI program can be written in any language and receives it's input via environment variables. The program's output should present it's mime type in plain text, followed by a carriage return and newline, and then any data which is representable via a sequence of u8 bytes. This can be plain text but does not have to be.

CGI environment vars

Var Meaning
DOCUMENT_ROOT The root directory of your server
QUERY_STRING The query string
REMOTE_ADDR The IP address of the client
REQUEST_URI The interpreted pathname of the requested document or CGI (relative to the document root)
SCRIPT_FILENAME The full pathname of the current CGI
SCRIPT_NAME The interpreted pathname of the current CGI (relative to the document root)
SERVER_NAME Your server's fully qualified domain name (e.g. www.cgi101.com)
SERVER_PORT The port number your server is listening on
SERVER_SOFTWARE The server software you're using
REQUEST_BODY The path to a temporary file containing any content uploaded to the server

ScriptAlias

The ScriptAlias directive allows passing requests to a CGI program without the cgi-bin directory or program name appearing in the url. In this way, dynamic content can be served without revealing to the client that a CGI program is being run or what the nature of that program is. This might be desireable if, for instance, one is using php scripting and doesn't wish to make that readily known to potential attackers.

Dependencies

~8–18MB
~246K SLoC