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Diffstat (limited to 'web/atward/src/main.rs')
| -rw-r--r-- | web/atward/src/main.rs | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/web/atward/src/main.rs b/web/atward/src/main.rs new file mode 100644 index 0000000000..eb2603a226 --- /dev/null +++ b/web/atward/src/main.rs @@ -0,0 +1,200 @@ +//! 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::input::cookies; +use rouille::{Request, Response}; + +#[cfg(test)] +mod tests; + +/// A query handler 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 Handler { + /// 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(&Query, regex::Captures<'s>) -> Option<String>, +} + +/// An Atward query supplied by a user. +#[derive(Debug, PartialEq)] +struct Query { + /// Query string itself. + query: String, + + /// Should Sourcegraph be used instead of cgit? + cs: bool, +} + +/// Helper function for setting a parameter based on a query +/// parameter. +fn query_setting(req: &Request, config: &mut bool, param: &str) { + match req.get_param(param) { + Some(s) if s == "true" => *config = true, + Some(s) if s == "false" => *config = false, + _ => {} + } +} + +impl Query { + fn from_request(req: &Request) -> Option<Query> { + // First extract the actual search query ... + let mut query = match req.get_param("q") { + Some(query) => Query { query, cs: false }, + None => return None, + }; + + // ... then apply settings to it. Settings in query parameters + // take precedence over cookies. + for cookie in cookies(req) { + match cookie { + ("cs", "true") => { + query.cs = true; + } + _ => {} + } + } + + query_setting(req, &mut query.cs, "cs"); + + Some(query) + } +} + +#[cfg(test)] +impl From<&str> for Query { + fn from(query: &str) -> Query { + Query { + query: query.to_string(), + cs: false, + } + } +} + +/// 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) + } +} + +/// Create a URL to a path in Sourcegraph. +fn sourcegraph_path_url(path: &str) -> String { + format!("https://cs.tvl.fyi/depot/-/tree/{}", path) +} +/// Definition of all supported query handlers in atward. +fn handlers() -> Vec<Handler> { + vec![ + // Bug IDs (e.g. b/123) + Handler { + pattern: Regex::new("^b/(?P<bug>\\d+)$").unwrap(), + target: |_, captures| Some(format!("https://b.tvl.fyi/{}", &captures["bug"])), + }, + // Changelists (e.g. cl/42) + Handler { + pattern: Regex::new("^cl/(?P<cl>\\d+)$").unwrap(), + target: |_, captures| Some(format!("https://cl.tvl.fyi/{}", &captures["cl"])), + }, + // Non-parameterised short hostnames should redirect to $host.tvl.fyi + Handler { + pattern: Regex::new("^(?P<host>b|cl|cs|code|at|todo)$").unwrap(), + target: |_, captures| Some(format!("https://{}.tvl.fyi/", &captures["host"])), + }, + // Depot revisions (e.g. r/3002) + Handler { + pattern: Regex::new("^r/(?P<rev>\\d+)$").unwrap(), + target: |_, captures| { + Some(format!( + "https://code.tvl.fyi/commit/?id=refs/r/{}", + &captures["rev"] + )) + }, + }, + // Depot paths (e.g. //web/atward or //ops/nixos/whitby/default.nix) + // TODO(tazjin): Add support for specifying lines in a query parameter + Handler { + pattern: Regex::new("^//(?P<path>[a-zA-Z].*)?$").unwrap(), + target: |query, captures| { + // Pass an empty string if the path is missing, to + // redirect to the depot root. + let path = captures.name("path").map(|m| m.as_str()).unwrap_or(""); + + if query.cs { + Some(sourcegraph_path_url(path)) + } else { + Some(cgit_url(path)) + } + }, + }, + ] +} + +/// Attempt to match against all known query types, and return the +/// destination URL if one is found. +fn dispatch(handlers: &[Handler], query: &Query) -> Option<String> { + for handler in handlers { + if let Some(captures) = handler.pattern.captures(&query.query) { + if let Some(destination) = (handler.target)(query, captures) { + return Some(destination); + } + } + } + + None +} + +/// Return the opensearch.xml file which is required for adding atward +/// as a search engine in Firefox. +fn opensearch() -> Response { + Response::text(include_str!("opensearch.xml")) + .with_unique_header("Content-Type", "application/opensearchdescription+xml") +} + +/// Render the atward index page which gives users some information +/// about how to use the service. +fn index() -> Response { + Response::html(include_str!(env!("ATWARD_INDEX_HTML"))) +} + +/// Render the fallback page which informs users that their query is +/// unsupported. +fn fallback() -> Response { + Response::text("error for emphasis that i am angery and the query whimchst i angery atward") + .with_status_code(404) +} + +fn main() { + let queries = handlers(); + 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(), || { + if request.url() == "/opensearch.xml" { + return opensearch(); + } + + let query = match Query::from_request(&request) { + Some(q) => q, + None => return index(), + }; + + match dispatch(&queries, &query) { + None => fallback(), + Some(destination) => Response::redirect_303(destination), + } + }) + }); +} |