add webfinger handler

Cargo.toml

@@ -6,4 +6,7 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-rocket = "=0.5.0-rc.3"
+lazy_static = "1.4.0"
+regex = "1.8.3"
+rocket = { version = "=0.5.0-rc.3", features = ["json"] }
+serde = { version = "1.0.163", features = ["derive"] }

Rocket.toml

@@ -0,0 +1,2 @@
+[default]
+address = "0.0.0.0"

src/ctx.rs

@@ -0,0 +1,8 @@
+pub mod db;
+pub mod user;
+
+pub use db::DB;
+
+pub struct Ctx {
+  pub db: Box<dyn DB>,
+}

src/ctx/db.rs

@@ -0,0 +1,30 @@
+use super::user;
+
+pub trait DB : Send + Sync {
+  fn new(&self, d: &user::Id) -> Result<(), String>;
+  fn delete(&self, d: &user::Id) -> Result<(), String>;
+  fn exists(&self, d: &user::Id) -> Result<bool, String>;
+
+  fn get_profile(&self, id: &user::Id) -> Result<user::Profile, String>;
+  fn set_profile(&self, id: &user::Id, d: user::Profile) -> Result<user::Profile, String>;
+}
+
+pub struct Null;
+impl DB for Null {
+  fn new(&self, d: &user::Id) -> Result<(), String> {
+    Err("not implemented".to_owned())
+  }
+  fn delete(&self, d: &user::Id) -> Result<(), String> {
+    Err("not implemented".to_owned())
+  }
+  fn exists(&self, d: &user::Id) -> Result<bool, String> {
+    Err("not implemented".to_owned())
+  }
+
+  fn get_profile(&self, id: &user::Id) -> Result<user::Profile, String> {
+    Err("not implemented".to_owned())
+  }
+  fn set_profile(&self, id: &user::Id, d: user::Profile) -> Result<user::Profile, String> {
+    Err("not implemented".to_owned())
+  }
+}

src/ctx/user.rs

@@ -0,0 +1,43 @@
+use lazy_static::lazy_static;
+use regex::Regex;
+
+pub struct Data {
+  id: Id,
+  profile: Option<Profile>,
+}
+pub struct Id {
+  name: String,
+  host: Option<String>,
+}
+pub struct Profile {
+  name: String,
+}
+
+
+impl Data {
+  fn get_profile(&self) -> Result<Profile, String> {
+    Err("not implemented".to_owned())
+  }
+  fn set_profile(&self, d: &Profile) -> Result<(), String> {
+    Err("not implemented".to_owned())
+  }
+}
+
+// hello@world.com -> Id {hello, world.com}
+pub fn parse_id(v: &str) -> Result<Id, String> {
+  lazy_static! {
+    static ref RE: Regex =  Regex::new(r"^([A-Za-z0-9_]+)(?:@([A-Za-z0-9\-\.]+))?$").unwrap();
+  }
+  match RE.captures(v) {
+    Some(caps) => Ok(Id {
+      name: caps.get(1).unwrap().as_str().to_owned(),
+      host: caps.get(2).map_or(None, |m| Some(m.as_str().to_owned())),
+    }),
+    None => Err("invalid idstr".to_owned()),
+  }
+}
+impl Id {
+  fn to_string(&self, default_host: &str) -> String {
+    format!("{}@{}", self.name, self.host.as_deref().unwrap_or(default_host))
+  }
+}

src/handler.rs

@@ -0,0 +1 @@
+pub mod webfinger;

src/handler/webfinger.rs

@@ -0,0 +1,56 @@
+use rocket::{get, Responder, State};
+use rocket::serde::json::Json;
+use serde::Serialize;
+
+use crate::ctx;
+use crate::ctx::Ctx;
+
+#[derive(Serialize)]
+pub struct WebFinger {
+    subject: String,
+    aliases: Vec<String>,
+}
+
+#[derive(Responder)]
+pub enum WebFingerResponse {
+  #[response(status = 200, content_type = "json")]
+  Found(Json<WebFinger>),
+
+  #[response(status = 404)]
+  Missing(String),
+
+  #[response(status = 400)]
+  ParseError(String),
+
+  #[response(status = 500)]
+  InternalError(String),
+}
+
+#[get("/?<resource>")]
+pub fn main(ctx: &State<Ctx>, resource: &str) -> WebFingerResponse {
+  match parse_resource(&resource) {
+    Ok(("acct", idstr)) | Ok(("", idstr)) => match ctx::user::parse_id(idstr) {
+      Ok(id) => match ctx.db.exists(&id) {
+        Ok(true) => WebFingerResponse::Found(Json(WebFinger {
+          subject: resource.to_owned(),
+          aliases: vec![resource.to_owned()],
+        })),
+
+        Ok(false) => WebFingerResponse::Missing(format!("unknown resource: {}", resource)),
+        Err(msg) => WebFingerResponse::InternalError(format!("error: {}", msg))
+      }
+      Err(msg) => WebFingerResponse::ParseError(format!("error: {}", msg)),
+    },
+    Ok((kind, _)) => WebFingerResponse::ParseError(format!("error: unknown kind, {}", kind)),
+    Err(msg) => WebFingerResponse::ParseError(format!("error: {}", msg)),
+  }
+}
+
+fn parse_resource(v: &str) -> Result<(&str, &str), String> {
+  let mut toks = v.split(':');
+  match (toks.next(), toks.next(), toks.next()) {
+    (Some(id),   None,     None) => Ok(("",   id)),
+    (Some(kind), Some(id), None) => Ok((kind, id)),
+    _ => Err(format!("invalid resource specifier: {}", v)),
+  }
+}

src/main.rs

@@ -1,11 +1,16 @@
-#[macro_use] extern crate rocket;
+mod ctx;
+mod handler;
 
-#[get("/")]
-fn index() -> &'static str {
-    "Hello, world!"
-}
+use rocket;
 
-#[launch]
-fn rocket() -> _ {
-    rocket::build().mount("/", routes![index])
+use ctx::Ctx;
+
+#[rocket::launch]
+fn launch() -> _ {
+  let ctx = Ctx {
+    db: Box::new(ctx::db::Null {}),
+  };
+  rocket::build().
+      manage(ctx).
+      mount("/.well-known/webfinger", rocket::routes![handler::webfinger::main])
 }