Add shared secret key authorization to rpc.

Not TLS yet, but we can at least authenticate clients... in clear
text!

dicebot/src/bin/tonic_client.rs

@@ -1,9 +1,27 @@
 use tenebrous_rpc::protos::dicebot::UserIdRequest;
 use tenebrous_rpc::protos::dicebot::{dicebot_client::DicebotClient, GetVariableRequest};
+use tonic::{metadata::MetadataValue, transport::Channel, Request};
+
+async fn create_client(
+    shared_secret: &str,
+) -> Result<DicebotClient<Channel>, Box<dyn std::error::Error>> {
+    let channel = Channel::from_static("http://0.0.0.0:9090")
+        .connect()
+        .await?;
+
+    let bearer = MetadataValue::from_str(&format!("Bearer {}", shared_secret))?;
+
+    let client = DicebotClient::with_interceptor(channel, move |mut req: Request<()>| {
+        req.metadata_mut().insert("authorization", bearer.clone());
+        Ok(req)
+    });
+
+    Ok(client)
+}
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let mut client = DicebotClient::connect("http://0.0.0.0:9090").await?;
+    let mut client = create_client("example-key").await?;
 
     // let request = tonic::Request::new(GetVariableRequest {
     //     user_id: "@projectmoon:agnos.is".into(),

dicebot/src/config.rs

@@ -57,6 +57,11 @@ struct BotConfig {
     /// What address and port to run the RPC service on. If not
     /// specified, RPC will not be enabled.
     rpc_addr: Option<String>,
+
+    /// The shared secret key between the bot and any RPC clients that
+    /// want to connect to it. The RPC server will reject any clients
+    /// that don't present the shared key.
+    rpc_key: Option<String>,
 }
 
 /// The "database" section of the config file.
@@ -90,6 +95,12 @@ impl BotConfig {
     fn rpc_addr(&self) -> Option<String> {
         self.rpc_addr.clone()
     }
+
+    #[inline]
+    #[must_use]
+    fn rpc_key(&self) -> Option<String> {
+        self.rpc_key.clone()
+    }
 }
 
 /// Represents the toml config file for the dicebot. The sections of
@@ -153,6 +164,12 @@ impl Config {
     pub fn rpc_addr(&self) -> Option<String> {
         self.bot.as_ref().and_then(|bc| bc.rpc_addr())
     }
+
+    #[inline]
+    #[must_use]
+    pub fn rpc_key(&self) -> Option<String> {
+        self.bot.as_ref().and_then(|bc| bc.rpc_key())
+    }
 }
 
 #[cfg(test)]

dicebot/src/error.rs

@@ -4,6 +4,7 @@ use crate::commands::CommandError;
 use crate::config::ConfigError;
 use crate::db::errors::DataError;
 use thiserror::Error;
+use tonic::metadata::errors::InvalidMetadataValue;
 
 #[derive(Error, Debug)]
 pub enum BotError {
@@ -101,6 +102,9 @@ pub enum BotError {
 
     #[error("address parsing error: {0}")]
     AddressParseError(#[from] AddrParseError),
+
+    #[error("invalid metadata value: {0}")]
+    TonicInvalidMetadata(#[from] InvalidMetadataValue),
 }
 
 #[derive(Error, Debug)]

dicebot/src/rpc/mod.rs

@@ -0,0 +1,50 @@
+use crate::error::BotError;
+use crate::{config::Config, db::sqlite::Database};
+use log::{info, warn};
+use matrix_sdk::Client;
+use service::DicebotRpcService;
+use std::sync::Arc;
+use tenebrous_rpc::protos::dicebot::dicebot_server::DicebotServer;
+use tonic::{metadata::MetadataValue, transport::Server, Request, Status};
+
+pub(crate) mod service;
+
+pub async fn serve_grpc(
+    config: &Arc<Config>,
+    db: &Database,
+    client: &Client,
+) -> Result<(), BotError> {
+    match config.rpc_addr().zip(config.rpc_key()) {
+        Some((addr, rpc_key)) => {
+            let expected_bearer = MetadataValue::from_str(&format!("Bearer {}", rpc_key))?;
+            let addr = addr.parse()?;
+
+            let rpc_service = DicebotRpcService {
+                db: db.clone(),
+                config: config.clone(),
+                client: client.clone(),
+            };
+
+            info!("Serving Dicebot gRPC service on {}", addr);
+
+            let interceptor = move |req: Request<()>| match req.metadata().get("authorization") {
+                Some(bearer) if bearer == expected_bearer => Ok(req),
+                _ => Err(Status::unauthenticated("No valid auth token")),
+            };
+
+            let server = DicebotServer::with_interceptor(rpc_service, interceptor);
+
+            Server::builder()
+                .add_service(server)
+                .serve(addr)
+                .await
+                .map_err(|e| e.into())
+        }
+        _ => noop().await,
+    }
+}
+
+pub async fn noop() -> Result<(), BotError> {
+    warn!("RPC address or shared secret not specified. Not enabling gRPC.");
+    Ok(())
+}

dicebot/src/rpc/service.rs

@@ -4,18 +4,15 @@ use crate::matrix;
 use crate::{config::Config, db::sqlite::Database};
 use futures::stream;
 use futures::{StreamExt, TryFutureExt, TryStreamExt};
-use log::info;
-use matrix_sdk::{identifiers::UserId, Client};
+use matrix_sdk::{identifiers::UserId, room::Joined, Client};
 use std::convert::TryFrom;
 use std::sync::Arc;
 use tenebrous_rpc::protos::dicebot::{
-    dicebot_server::{Dicebot, DicebotServer},
-    rooms_list_reply::Room,
-    GetAllVariablesReply, GetAllVariablesRequest, RoomsListReply, SetVariableReply,
-    SetVariableRequest, UserIdRequest,
+    dicebot_server::Dicebot, rooms_list_reply::Room, GetAllVariablesReply, GetAllVariablesRequest,
+    RoomsListReply, SetVariableReply, SetVariableRequest, UserIdRequest,
 };
 use tenebrous_rpc::protos::dicebot::{GetVariableReply, GetVariableRequest};
-use tonic::{transport::Server, Code, Request, Response, Status};
+use tonic::{Code, Request, Response, Status};
 
 impl From<BotError> for Status {
     fn from(error: BotError) -> Status {
@@ -29,10 +26,11 @@ impl From<DataError> for Status {
     }
 }
 
-pub struct DicebotRpcService {
-    config: Arc<Config>,
-    db: Database,
-    client: Client,
+#[derive(Clone)]
+pub(super) struct DicebotRpcService {
+    pub(super) config: Arc<Config>,
+    pub(super) db: Database,
+    pub(super) client: Client,
 }
 
 #[tonic::async_trait]
@@ -93,13 +91,13 @@ impl Dicebot for DicebotRpcService {
             .await?;
 
         let mut rooms: Vec<Room> = stream::iter(rooms_for_user)
-            .filter_map(|room| async move {
-                let rooms = room.display_name().await.map(|room_name| Room {
+            .filter_map(|room: Joined| async move {
+                let room: Result<Room, _> = room.display_name().await.map(|room_name| Room {
                     room_id: room.room_id().to_string(),
                     display_name: room_name,
                 });
 
-                Some(rooms)
+                Some(room)
             })
             .err_into::<BotError>()
             .try_collect()
@@ -116,33 +114,3 @@ impl Dicebot for DicebotRpcService {
         Ok(Response::new(RoomsListReply { rooms }))
     }
 }
-
-pub async fn serve_grpc(
-    config: &Arc<Config>,
-    db: &Database,
-    client: &Client,
-) -> Result<(), BotError> {
-    match config.rpc_addr() {
-        Some(addr) => {
-            let addr = addr.parse()?;
-            let rpc_service = DicebotRpcService {
-                db: db.clone(),
-                config: config.clone(),
-                client: client.clone(),
-            };
-
-            info!("Serving Dicebot gRPC service on {}", addr);
-            Server::builder()
-                .add_service(DicebotServer::new(rpc_service))
-                .serve(addr)
-                .await
-                .map_err(|e| e.into())
-        }
-        _ => noop().await,
-    }
-}
-
-pub async fn noop() -> Result<(), BotError> {
-    info!("RPC address not specified. Not enabling gRPC.");
-    Ok(())
-}