dece
237959fb42
Rustls is fine but it's hard to change the default "secure" behaviour for Gemini usage. Not that Gemini is unsecure but things like self-signed client certificates should not be such a stupidly hard thing to accept.
4.2 KiB
Opal
Opal is a Gemini server written in Rust. It is meant to serve dynamic content through CGI and does not serve static files. In a way, it is a companion project to the Agate Gemini server which only serves static files, trying to focus on a smaller set of features but do them correctly.
Opal uses the openssl Rust bindings, which work with OpenSSL and LibreSSL, so
it should work properly on those platforms. I only support Linux systems but
feel free to patch stuff!
Usage
Use opal -h to get a list of options. There is no config file.
CGI support
Opal tries to implement RFC 3875 (CGI 1.1) and provides all the required environment variables to processes. It also add a bunch of Gemini specific variables, like a lot of other servers (Gemserv, Gmid, Gmnisrv, …). The environment for the subprocess is cleaned and should only contain those variables.
| Presence | Variable | Description |
|---|---|---|
| always | GATEWAY_INTERFACE | "CGI/1.1" |
| always | REMOTE_ADDR | Peer IP address and port |
| always | REMOTE_HOST | Same as REMOTE_ADDR |
| always | REQUEST_METHOD | Empty string for compatibility |
| always | SCRIPT_NAME | Script name part of the URL path |
| always | SERVER_NAME | Hostname used for SNI |
| always | SERVER_PORT | Port where the request has been received |
| always | SERVER_PROTOCOL | "GEMINI" |
| always | SERVER_SOFTWARE | "opal/version", e.g. "opal/0.1.0" |
| always | GEMINI_DOCUMENT_ROOT | CGI root |
| always | GEMINI_SCRIPT_FILENAME | CGI script that matched the URL path |
| always | GEMINI_URL | Full URL, normalized |
| always | GEMINI_URL_PATH | URL path, normalized |
| always | TLS_VERSION | TLS version, e.g. "TLSv1.3" |
| always | TLS_CIPHER | TLS cipher suite, e.g. "TLS_AES_256_GCM_SHA384" |
| optional | PATH_INFO | Path passed to the CGI process after the script name |
| optional | QUERY_STRING | Query string if provided, still URL-encoded |
| client cert | AUTH_TYPE | "CERTIFICATE" if one is provided |
| client cert | REMOTE_USER | Subject common name (empty if unavailable) |
| client cert | TLS_CLIENT_ISSUER | Issuer common name (empty if unavailable) |
| client cert | TLS_CLIENT_HASH | Digest of the DER reprensetation of the cert |
| client cert | TLS_CLIENT_NOT_AFTER | Validity end date, RFC 3339 format |
| client cert | TLS_CLIENT_NOT_BEFORE | Validity start date, RFC 3339 format |
Opal does not provide CONTENT_LENGTH, CONTENT_TYPE, REMOTE_IDENT because
they do not make much sense in Gemini. PATH_TRANSLATED is also not implemented
by pure laziness.
The TLS_CLIENT_HASH is a string that starts with "SHA256:" followed by the
SHA256 digest of the DER representation of the client certificate, as an
uppercase hex-string.
It can be a bit confusing which variable represent what data, especially those
related to the URL and the path. Take the following request as example:
gemini://localhost/env/sub1/sub2?search=élément. Suppose our CGI root, in
/cgi, contains the executable script named env. The variables will be:
GEMINI_DOCUMENT_ROOT=/cgi
GEMINI_SCRIPT_FILENAME=/cgi/env
GEMINI_URL=gemini://localhost/env/sub1/sub2?search=%C3%A9l%C3%A9ment
GEMINI_URL_PATH=/env/sub1/sub2
SCRIPT_NAME=/env
PATH_INFO=/sub1/sub2
QUERY_STRING=search=%C3%A9l%C3%A9ment