tvl-depot/web/atward/src/main.rs

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//! Atward implements TVL's redirection service, living at
//! atward.tvl.fyi
//!
//! This service is designed to be added as a search engine to web
//! browsers and attempts to send users to useful locations based on
//! their search query (falling back to another search engine).
use regex::Regex;
use rouille::Response;
/// A query type supported by atward. It consists of a pattern on
/// which to match and trigger the query, and a function to execute
/// that returns the target URL.
struct Query {
/// Regular expression on which to match the query string.
pattern: Regex,
/// Function to construct the target URL. If the pattern matches,
/// this is invoked with the captured matches and the entire URI.
///
/// Returning `None` causes atward to fall through to the next
/// query (and eventually to the default search engine).
target: for<'s> fn(&'s str, regex::Captures<'s>) -> Option<String>,
}
/// Create a URL to a file (and, optionally, specific line) in cgit.
fn cgit_url(path: &str) -> String {
if path.ends_with(".md") {
format!("https://code.tvl.fyi/about/{}", path)
} else {
format!("https://code.tvl.fyi/tree/{}", path)
}
}
/// Definition of all supported queries in atward.
fn queries() -> Vec<Query> {
vec![
// Bug IDs (e.g. b/123)
Query {
pattern: Regex::new("^b/(?P<bug>\\d+)$").unwrap(),
target: |_, captures| Some(format!("https://b.tvl.fyi/{}", &captures["bug"])),
},
// Changelists (e.g. cl/42)
Query {
pattern: Regex::new("^cl/(?P<cl>\\d+)$").unwrap(),
target: |_, captures| Some(format!("https://cl.tvl.fyi/{}", &captures["cl"])),
},
// Depot paths (e.g. //web/atward or //ops/nixos/whitby/default.nix)
// TODO(tazjin): Add support for specifying lines in a query parameter
Query {
pattern: Regex::new("^//(?P<path>[a-zA-Z].*)$").unwrap(),
target: |_, captures| Some(cgit_url(&captures["path"])),
},
]
}
/// Attempt to match against all known query types, and return the
/// destination URL if one is found.
fn dispatch(queries: &[Query], uri: &str) -> Option<String> {
for query in queries {
if let Some(captures) = query.pattern.captures(uri) {
if let Some(destination) = (query.target)(uri, captures) {
return Some(destination);
}
}
}
None
}
fn fallback() -> Response {
Response::text("no match for atward whimchst query").with_status_code(404)
}
fn main() {
let queries = queries();
let address = std::env::var("ATWARD_LISTEN_ADDRESS")
.expect("ATWARD_LISTEN_ADDRESS environment variable must be set");
rouille::start_server(&address, move |request| {
rouille::log(&request, std::io::stderr(), || {
let query = match request.get_param("q") {
Some(q) => q,
None => return fallback(),
};
match dispatch(&queries, &query) {
None => fallback(),
Some(destination) => Response::redirect_303(destination),
}
})
});
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn bug_query() {
assert_eq!(
dispatch(&queries(), "b/42"),
Some("https://b.tvl.fyi/42".to_string())
);
assert_eq!(dispatch(&queries(), "something only mentioning b/42"), None,);
assert_eq!(dispatch(&queries(), "b/invalid"), None,);
}
#[test]
fn cl_query() {
assert_eq!(
dispatch(&queries(), "cl/42"),
Some("https://cl.tvl.fyi/42".to_string())
);
assert_eq!(
dispatch(&queries(), "something only mentioning cl/42"),
None,
);
assert_eq!(dispatch(&queries(), "cl/invalid"), None,);
}
#[test]
fn depot_path_query() {
assert_eq!(
dispatch(&queries(), "//web/atward/default.nix"),
Some("https://code.tvl.fyi/tree/web/atward/default.nix".to_string()),
);
assert_eq!(
dispatch(&queries(), "//nix/readTree/README.md"),
Some("https://code.tvl.fyi/about/nix/readTree/README.md".to_string()),
);
assert_eq!(dispatch(&queries(), "/not/a/depot/path"), None);
}
}