agunua 1.2

A library for the development of Gemini clients

Agunua

Agunua is a Python library for the development of Gemini clients.

Installation

You need Python 3, netaddr, PySocks and PyOpenSSL. You can install the dependencies with pip pip3 install agunua.

Usage

import Agunua
...
u = Agunua.GeminiUri(url)
print(u)

Parameters in the GeminiUri() constructor (you can find their default values at the beginning of the file Agunua/__init__.py):

• url: the URL to load
• insecure: accept invalid certificates (signed by unknown CA, for instance)
• tofu: performs TOFU (Trust On First Use) validation. It is a string, not a boolean. If empty, we disable TOFU. Otherwise, it is the directory of TOFU data.
• accept_expired: accept expired certificates (insecure = True is not sufficient for that)
• get_content: retrieve the actual resource (default is to get metadata only)
• parse_content: if it is gemtext (text/gemini), parse and extract links
• maxlines: if it is text, maximum number of lines retrieved. Set to None if you don't want a limit
• maxsize: maximum size in bytes to retrieve. Set to None if you don't want a limit
• binary: (automatic if the content is text). Retrieve as binary content, don't play with end-of-lines
• follow-redirect: automatically follow Gemini redirections
• redirect_depth: maximum number of redirections followed
• iri: handle IRI (URI in Unicode)
• force_ipv4: use the IPv4 protocol only
• force_ipv6: use the IPv6 protocol only
• connect_to: use the host name in the URI for the Gemini request but connect only to this host (name or address). Useful when the host is multihomed.
• use_socks: use a SOCKS5 proxy (for instance for .onion capsules). The value must be a tuple (socks proxy name, socks proxy port).

If the URL is invalid (wrong syntax), you won't get a GeminiUri object. If you get one, it does not mean the resource has been retrieved successfully. See the attribute network_success for that, and then the attribute status_code (that you have to interpret yourself, in most cases).

Attributes of GeminiUri objects (not all of them will always be present; for instance, if you did not ask to get content, you won't have an attribute size; if the status code is not 20 - OK - you won't get a mediatype; etc):

• network_success: resource was retrieved successfully
• status_code: if retrieved successfully, the Gemini two-digit status code
• error: if network_success is false, this is the reason
• ip_address: IP address used for the retrieval
• meta: the meta field of the Gemini protocol. It depends on the status code. Read the Gemini specification for detail.
• binary: if you asked for binary access, it will be True. If you asked for text access (binary=False in the constructor) and asked to ge the content (get_content=True), it will be set to False if decoding went well and True if the decoding failed, for instance because the file did not match the announced "charset".
• links: an array of the links found in the document (if you've set parse_content)
• payload: the content
• size: the size of the payload. Since Gemini does not have a way to indicate at the beginning the payload size, this will be obtained only if get_contentis true, and it will be limited by the parameter maxsize
• mediatype: the media type (MIME type) of the resource, such as text/gemini or image/jpeg
• lang: the human language of the resource, as standardized in BCP 47
• charset: actually the encoding of the resource such as UTF-8 or US-ASCII
• tls_version: the TLS version, for instance, "TLSv1.3"
• no_shutdown: set to True if the server did not properly close the TLS session. It may mean that the content was truncated. Meaningful only with get_content=True and if you asked for the whole file.
• The rest is related to certificates:
• issuer: the CA (Certificate Authority)
• subject: the name in the certificate (X.509 calls it "subject")
• expired: the certificate has expired
• cert_not_after: expiration date
• cert_not_before: inception date
• cert_algo: algorithm used by the CA
• cert_key_type: algorithm of the public key
• keystring: the public key
• cert_key_size: size of the public key

See sample-client.py. Agunua is used in the Manisha monitoring tool and in the Lupa crawler.

Command-line client

agunua is a simple Gemini command-line client, a bit like curl. You can just call:

agunua YOUR-URL

And you will get its content. Most parameters of the GeminiUri() constructor can be set via options. Important: the default value is not always the same with the command-line tool. For instance, it defaults to actually retrieving the content. Here are the options:

• --maximum-time: maximum time in seconds before giving in if the server does not respond
• --insecure: do not check the certificate
• --no-tofu: do not perform TOFU (Trust On First Use) validation
• --accept-expired-certificate: even with --insecure, expired certificates are not accepted unless you use also this option
• --not-follow-redirect: by default, the tool follows Gemini redirections but you can use this option to avoid it
• --verbose: more talkative
• --display-links: instead of displaying the content, display the links it contains
• --maxlines: maximum number of lines to retrieve (for text files). Set to 0 for "no limit"
• --maxsize: maximum amount of bytes to retrieve. Set to 0 for "no limit"
• --connect-to: connect to this specific host (name or IP address) not to the one mentioned in the URL
• --socks: connect through this SOCKS proxy, expressed as host:port
• --binary: even if this is a text file, download as binary
• --force-ipv4: use only the IPv4 protocol
• --force-ipv6: use only the IPv6 protocol

Name

Agunua is a melanesian serpent god. Caduceus would have been better for a Python + Gemini project since there are two snakes on a caduceus but it was already used.

License

GPL. See LICENSE.

Recent changes

See the file CHANGES.

Authors

Stéphane Bortzmeyer [e-mail].

Reference site

https://framagit.org/bortzmeyer/agunua/ Use the Gitlab issue tracker to report bugs or wishes. But you can of course also access it with gemini at gemini://gemini.bortzmeyer.org/software/agunua/

Other Gemini clients in Python

• https://tildegit.org/solderpunk/gemini-demo-1 Very simple but working client
• https://github.com/cbrews/ignition Modelled on the requests library so very convenient for programmers
• https://git.carcosa.net/jmcbray/gusmobile/ Good code
• https://git.sr.ht/~fkfd/picross
• https://github.com/apellis/pygemini No longer maintained