gRPC Support (#20)

src-tauri/grpc/src/codec.rs

@@ -0,0 +1,52 @@
+use prost_reflect::prost::Message;
+use prost_reflect::{DynamicMessage, MethodDescriptor};
+use tonic::codec::{Codec, DecodeBuf, Decoder, EncodeBuf, Encoder};
+use tonic::Status;
+
+#[derive(Clone)]
+pub struct DynamicCodec(MethodDescriptor);
+
+impl DynamicCodec {
+    #[allow(dead_code)]
+    pub fn new(md: MethodDescriptor) -> Self {
+        Self(md)
+    }
+}
+
+impl Codec for DynamicCodec {
+    type Encode = DynamicMessage;
+    type Decode = DynamicMessage;
+    type Encoder = Self;
+    type Decoder = Self;
+
+    fn encoder(&mut self) -> Self::Encoder {
+        self.clone()
+    }
+
+    fn decoder(&mut self) -> Self::Decoder {
+        self.clone()
+    }
+}
+
+impl Encoder for DynamicCodec {
+    type Item = DynamicMessage;
+    type Error = Status;
+
+    fn encode(&mut self, item: Self::Item, dst: &mut EncodeBuf<'_>) -> Result<(), Self::Error> {
+        item.encode(dst)
+            .expect("buffer is too small to decode this message");
+        Ok(())
+    }
+}
+
+impl Decoder for DynamicCodec {
+    type Item = DynamicMessage;
+    type Error = Status;
+
+    fn decode(&mut self, src: &mut DecodeBuf<'_>) -> Result<Option<Self::Item>, Self::Error> {
+        let mut msg = DynamicMessage::new(self.0.output());
+        msg.merge(src)
+            .map_err(|err| Status::internal(err.to_string()))?;
+        Ok(Some(msg))
+    }
+}

src-tauri/grpc/src/json_schema.rs

@@ -0,0 +1,179 @@
+use prost_reflect::{DescriptorPool, MessageDescriptor};
+use prost_types::field_descriptor_proto;
+use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
+
+#[derive(Default, Serialize, Deserialize)]
+#[serde(default, rename_all = "camelCase")]
+pub struct JsonSchemaEntry {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    title: Option<String>,
+
+    #[serde(rename = "type")]
+    type_: JsonType,
+
+    #[serde(skip_serializing_if = "Option::is_none")]
+    description: Option<String>,
+
+    #[serde(skip_serializing_if = "Option::is_none")]
+    properties: Option<HashMap<String, JsonSchemaEntry>>,
+
+    #[serde(rename = "enum", skip_serializing_if = "Option::is_none")]
+    enum_: Option<Vec<String>>,
+
+    /// Don't allow any other properties in the object
+    additional_properties: bool,
+
+    /// Set all properties to required
+    #[serde(skip_serializing_if = "Option::is_none")]
+    required: Option<Vec<String>>,
+
+    #[serde(skip_serializing_if = "Option::is_none")]
+    items: Option<Box<JsonSchemaEntry>>,
+}
+
+enum JsonType {
+    String,
+    Number,
+    Object,
+    Array,
+    Boolean,
+    Null,
+    _UNKNOWN,
+}
+
+impl Default for JsonType {
+    fn default() -> Self {
+        JsonType::_UNKNOWN
+    }
+}
+
+impl serde::Serialize for JsonType {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        match self {
+            JsonType::String => serializer.serialize_str("string"),
+            JsonType::Number => serializer.serialize_str("number"),
+            JsonType::Object => serializer.serialize_str("object"),
+            JsonType::Array => serializer.serialize_str("array"),
+            JsonType::Boolean => serializer.serialize_str("boolean"),
+            JsonType::Null => serializer.serialize_str("null"),
+            JsonType::_UNKNOWN => serializer.serialize_str("unknown"),
+        }
+    }
+}
+
+impl<'de> serde::Deserialize<'de> for JsonType {
+    fn deserialize<D>(deserializer: D) -> Result<JsonType, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let s = String::deserialize(deserializer)?;
+        match s.as_str() {
+            "string" => Ok(JsonType::String),
+            "number" => Ok(JsonType::Number),
+            "object" => Ok(JsonType::Object),
+            "array" => Ok(JsonType::Array),
+            "boolean" => Ok(JsonType::Boolean),
+            "null" => Ok(JsonType::Null),
+            _ => Ok(JsonType::_UNKNOWN),
+        }
+    }
+}
+
+pub fn message_to_json_schema(
+    pool: &DescriptorPool,
+    message: MessageDescriptor,
+) -> JsonSchemaEntry {
+    let mut schema = JsonSchemaEntry {
+        title: Some(message.name().to_string()),
+        type_: JsonType::Object, // Messages are objects
+        ..Default::default()
+    };
+
+    let mut properties = HashMap::new();
+    message.fields().for_each(|f| match f.kind() {
+        prost_reflect::Kind::Message(m) => {
+            properties.insert(f.name().to_string(), message_to_json_schema(pool, m));
+        }
+        prost_reflect::Kind::Enum(e) => {
+            properties.insert(
+                f.name().to_string(),
+                JsonSchemaEntry {
+                    type_: map_proto_type_to_json_type(f.field_descriptor_proto().r#type()),
+                    enum_: Some(e.values().map(|v| v.name().to_string()).collect::<Vec<_>>()),
+                    ..Default::default()
+                },
+            );
+        }
+        _ => {
+            // TODO: Handle repeated label
+            match f.field_descriptor_proto().label() {
+                field_descriptor_proto::Label::Repeated => {
+                    // TODO: Handle more complex repeated types. This just handles primitives for now
+                    properties.insert(
+                        f.name().to_string(),
+                        JsonSchemaEntry {
+                            type_: JsonType::Array,
+                            items: Some(Box::new(JsonSchemaEntry {
+                                type_: map_proto_type_to_json_type(
+                                    f.field_descriptor_proto().r#type(),
+                                ),
+                                ..Default::default()
+                            })),
+                            ..Default::default()
+                        },
+                    );
+                }
+                _ => {
+                    // Regular JSON field
+                    properties.insert(
+                        f.name().to_string(),
+                        JsonSchemaEntry {
+                            type_: map_proto_type_to_json_type(f.field_descriptor_proto().r#type()),
+                            ..Default::default()
+                        },
+                    );
+                }
+            };
+        }
+    });
+
+    schema.properties = Some(properties);
+
+    // All proto 3 fields are optional, so maybe we could
+    // make this a setting?
+    // schema.required = Some(
+    //     message
+    //         .fields()
+    //         .map(|f| f.name().to_string())
+    //         .collect::<Vec<_>>(),
+    // );
+
+    schema
+}
+
+fn map_proto_type_to_json_type(proto_type: field_descriptor_proto::Type) -> JsonType {
+    match proto_type {
+        field_descriptor_proto::Type::Double => JsonType::Number,
+        field_descriptor_proto::Type::Float => JsonType::Number,
+        field_descriptor_proto::Type::Int64 => JsonType::Number,
+        field_descriptor_proto::Type::Uint64 => JsonType::Number,
+        field_descriptor_proto::Type::Int32 => JsonType::Number,
+        field_descriptor_proto::Type::Fixed64 => JsonType::Number,
+        field_descriptor_proto::Type::Fixed32 => JsonType::Number,
+        field_descriptor_proto::Type::Bool => JsonType::Boolean,
+        field_descriptor_proto::Type::String => JsonType::String,
+        field_descriptor_proto::Type::Group => JsonType::_UNKNOWN,
+        field_descriptor_proto::Type::Message => JsonType::Object,
+        field_descriptor_proto::Type::Bytes => JsonType::String,
+        field_descriptor_proto::Type::Uint32 => JsonType::Number,
+        field_descriptor_proto::Type::Enum => JsonType::String,
+        field_descriptor_proto::Type::Sfixed32 => JsonType::Number,
+        field_descriptor_proto::Type::Sfixed64 => JsonType::Number,
+        field_descriptor_proto::Type::Sint32 => JsonType::Number,
+        field_descriptor_proto::Type::Sint64 => JsonType::Number,
+    }
+}

src-tauri/grpc/src/lib.rs

@@ -0,0 +1,40 @@
+use prost_reflect::{DynamicMessage, SerializeOptions};
+use serde::{Deserialize, Serialize};
+
+mod codec;
+mod json_schema;
+pub mod manager;
+mod proto;
+
+pub fn serialize_options() -> SerializeOptions {
+    SerializeOptions::new().skip_default_fields(false)
+}
+
+#[derive(Serialize, Deserialize, Debug, Default)]
+#[serde(default, rename_all = "camelCase")]
+pub struct ServiceDefinition {
+    pub name: String,
+    pub methods: Vec<MethodDefinition>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Default)]
+#[serde(default, rename_all = "camelCase")]
+pub struct MethodDefinition {
+    pub name: String,
+    pub schema: String,
+    pub client_streaming: bool,
+    pub server_streaming: bool,
+}
+
+static SERIALIZE_OPTIONS: &'static SerializeOptions = &SerializeOptions::new()
+    .skip_default_fields(false)
+    .stringify_64_bit_integers(false);
+
+pub fn serialize_message(msg: &DynamicMessage) -> Result<String, String> {
+    let mut buf = Vec::new();
+    let mut se = serde_json::Serializer::pretty(&mut buf);
+    msg.serialize_with_options(&mut se, SERIALIZE_OPTIONS)
+        .map_err(|e| e.to_string())?;
+    let s = String::from_utf8(buf).expect("serde_json to emit valid utf8");
+    Ok(s)
+}

src-tauri/grpc/src/manager.rs

@@ -0,0 +1,280 @@
+use std::collections::HashMap;
+use std::path::PathBuf;
+
+use hyper::client::HttpConnector;
+use hyper::Client;
+use hyper_rustls::HttpsConnector;
+use prost_reflect::DescriptorPool;
+pub use prost_reflect::DynamicMessage;
+use serde_json::Deserializer;
+use tokio_stream::wrappers::ReceiverStream;
+use tokio_stream::StreamExt;
+use tonic::body::BoxBody;
+use tonic::transport::Uri;
+use tonic::{IntoRequest, IntoStreamingRequest, Streaming};
+
+use crate::codec::DynamicCodec;
+use crate::proto::{fill_pool, fill_pool_from_files, get_transport, method_desc_to_path};
+use crate::{json_schema, MethodDefinition, ServiceDefinition};
+
+#[derive(Clone)]
+pub struct GrpcConnection {
+    pool: DescriptorPool,
+    conn: Client<HttpsConnector<HttpConnector>, BoxBody>,
+    pub uri: Uri,
+}
+
+impl GrpcConnection {
+    pub async fn unary(
+        &self,
+        service: &str,
+        method: &str,
+        message: &str,
+    ) -> Result<DynamicMessage, String> {
+        let service = self.pool.get_service_by_name(service).unwrap();
+        let method = &service.methods().find(|m| m.name() == method).unwrap();
+        let input_message = method.input();
+
+        let mut deserializer = Deserializer::from_str(message);
+        let req_message = DynamicMessage::deserialize(input_message, &mut deserializer)
+            .map_err(|e| e.to_string())?;
+        deserializer.end().unwrap();
+
+        let mut client = tonic::client::Grpc::with_origin(self.conn.clone(), self.uri.clone());
+
+        let req = req_message.into_request();
+        let path = method_desc_to_path(method);
+        let codec = DynamicCodec::new(method.clone());
+        client.ready().await.unwrap();
+
+        Ok(client
+            .unary(req, path, codec)
+            .await
+            .map_err(|e| e.to_string())?
+            .into_inner())
+    }
+
+    pub async fn streaming(
+        &self,
+        service: &str,
+        method: &str,
+        stream: ReceiverStream<String>,
+    ) -> Result<Streaming<DynamicMessage>, String> {
+        let service = self.pool.get_service_by_name(service).unwrap();
+        let method = &service.methods().find(|m| m.name() == method).unwrap();
+
+        let mut client = tonic::client::Grpc::with_origin(self.conn.clone(), self.uri.clone());
+
+        let method2 = method.clone();
+        let req = stream
+            .map(move |s| {
+                let mut deserializer = Deserializer::from_str(&s);
+                let req_message = DynamicMessage::deserialize(method2.input(), &mut deserializer)
+                    .map_err(|e| e.to_string())
+                    .unwrap();
+                deserializer.end().unwrap();
+                req_message
+            })
+            .into_streaming_request();
+        let path = method_desc_to_path(method);
+        let codec = DynamicCodec::new(method.clone());
+        client.ready().await.unwrap();
+        Ok(client
+            .streaming(req, path, codec)
+            .await
+            .map_err(|s| s.to_string())?
+            .into_inner())
+    }
+
+    pub async fn client_streaming(
+        &self,
+        service: &str,
+        method: &str,
+        stream: ReceiverStream<String>,
+    ) -> Result<DynamicMessage, String> {
+        let service = self.pool.get_service_by_name(service).unwrap();
+        let method = &service.methods().find(|m| m.name() == method).unwrap();
+        let mut client = tonic::client::Grpc::with_origin(self.conn.clone(), self.uri.clone());
+
+        let req = {
+            let method = method.clone();
+            stream
+                .map(move |s| {
+                    let mut deserializer = Deserializer::from_str(&s);
+                    let req_message =
+                        DynamicMessage::deserialize(method.input(), &mut deserializer)
+                            .map_err(|e| e.to_string())
+                            .unwrap();
+                    deserializer.end().unwrap();
+                    req_message
+                })
+                .into_streaming_request()
+        };
+        let path = method_desc_to_path(method);
+        let codec = DynamicCodec::new(method.clone());
+        client.ready().await.unwrap();
+        Ok(client
+            .client_streaming(req, path, codec)
+            .await
+            .map_err(|s| s.to_string())?
+            .into_inner())
+    }
+
+    pub async fn server_streaming(
+        &self,
+        service: &str,
+        method: &str,
+        message: &str,
+    ) -> Result<Streaming<DynamicMessage>, String> {
+        let service = self.pool.get_service_by_name(service).unwrap();
+        let method = &service.methods().find(|m| m.name() == method).unwrap();
+        let input_message = method.input();
+
+        let mut deserializer = Deserializer::from_str(message);
+        let req_message = DynamicMessage::deserialize(input_message, &mut deserializer)
+            .map_err(|e| e.to_string())?;
+        deserializer.end().unwrap();
+
+        let mut client = tonic::client::Grpc::with_origin(self.conn.clone(), self.uri.clone());
+
+        let req = req_message.into_request();
+        let path = method_desc_to_path(method);
+        let codec = DynamicCodec::new(method.clone());
+        client.ready().await.unwrap();
+        Ok(client
+            .server_streaming(req, path, codec)
+            .await
+            .map_err(|s| s.to_string())?
+            .into_inner())
+    }
+}
+
+pub struct GrpcHandle {
+    pools: HashMap<String, DescriptorPool>,
+}
+
+impl Default for GrpcHandle {
+    fn default() -> Self {
+        let pools = HashMap::new();
+        Self { pools }
+    }
+}
+
+impl GrpcHandle {
+    pub async fn services_from_files(
+        &mut self,
+        id: &str,
+        uri: &Uri,
+        paths: Vec<PathBuf>,
+    ) -> Result<Vec<ServiceDefinition>, String> {
+        let pool = fill_pool_from_files(paths).await?;
+        self.pools.insert(self.get_pool_key(id, uri), pool.clone());
+        Ok(self.services_from_pool(&pool))
+    }
+    pub async fn services_from_reflection(
+        &mut self,
+        id: &str,
+        uri: &Uri,
+    ) -> Result<Vec<ServiceDefinition>, String> {
+        let pool = fill_pool(uri).await?;
+        self.pools.insert(self.get_pool_key(id, uri), pool.clone());
+        Ok(self.services_from_pool(&pool))
+    }
+
+    fn get_pool_key(&self, id: &str, uri: &Uri) -> String {
+        format!("{}-{}", id, uri)
+    }
+
+    fn services_from_pool(&self, pool: &DescriptorPool) -> Vec<ServiceDefinition> {
+        pool.services()
+            .map(|s| {
+                let mut def = ServiceDefinition {
+                    name: s.full_name().to_string(),
+                    methods: vec![],
+                };
+                for method in s.methods() {
+                    let input_message = method.input();
+                    def.methods.push(MethodDefinition {
+                        name: method.name().to_string(),
+                        server_streaming: method.is_server_streaming(),
+                        client_streaming: method.is_client_streaming(),
+                        schema: serde_json::to_string_pretty(&json_schema::message_to_json_schema(
+                            &pool,
+                            input_message,
+                        ))
+                        .unwrap(),
+                    })
+                }
+                def
+            })
+            .collect::<Vec<_>>()
+    }
+
+    pub async fn server_streaming(
+        &mut self,
+        id: &str,
+        uri: Uri,
+        proto_files: Vec<PathBuf>,
+        service: &str,
+        method: &str,
+        message: &str,
+    ) -> Result<Streaming<DynamicMessage>, String> {
+        self.connect(id, uri, proto_files)
+            .await?
+            .server_streaming(service, method, message)
+            .await
+    }
+
+    pub async fn client_streaming(
+        &mut self,
+        id: &str,
+        uri: Uri,
+        proto_files: Vec<PathBuf>,
+        service: &str,
+        method: &str,
+        stream: ReceiverStream<String>,
+    ) -> Result<DynamicMessage, String> {
+        self.connect(id, uri, proto_files)
+            .await?
+            .client_streaming(service, method, stream)
+            .await
+    }
+
+    pub async fn streaming(
+        &mut self,
+        id: &str,
+        uri: Uri,
+        proto_files: Vec<PathBuf>,
+        service: &str,
+        method: &str,
+        stream: ReceiverStream<String>,
+    ) -> Result<Streaming<DynamicMessage>, String> {
+        self.connect(id, uri, proto_files)
+            .await?
+            .streaming(service, method, stream)
+            .await
+    }
+
+    pub async fn connect(
+        &mut self,
+        id: &str,
+        uri: Uri,
+        proto_files: Vec<PathBuf>,
+    ) -> Result<GrpcConnection, String> {
+        let pool = match self.pools.get(id) {
+            Some(p) => p.clone(),
+            None => match proto_files.len() {
+                0 => fill_pool(&uri).await?,
+                _ => {
+                    let pool = fill_pool_from_files(proto_files).await?;
+                    self.pools.insert(id.to_string(), pool.clone());
+                    pool
+                }
+            },
+        };
+
+        let conn = get_transport();
+        let connection = GrpcConnection { pool, conn, uri };
+        Ok(connection)
+    }
+}

src-tauri/grpc/src/proto.rs

@@ -0,0 +1,226 @@
+use std::env::temp_dir;
+use std::ops::Deref;
+use std::path::PathBuf;
+use std::process::Command;
+use std::str::FromStr;
+
+use anyhow::anyhow;
+use hyper::client::HttpConnector;
+use hyper::Client;
+use hyper_rustls::{HttpsConnector, HttpsConnectorBuilder};
+use log::{debug, warn};
+use prost::Message;
+use prost_reflect::{DescriptorPool, MethodDescriptor};
+use prost_types::{FileDescriptorProto, FileDescriptorSet};
+use tokio::fs;
+use tokio_stream::StreamExt;
+use tonic::body::BoxBody;
+use tonic::codegen::http::uri::PathAndQuery;
+use tonic::transport::Uri;
+use tonic::Request;
+use tonic_reflection::pb::server_reflection_client::ServerReflectionClient;
+use tonic_reflection::pb::server_reflection_request::MessageRequest;
+use tonic_reflection::pb::server_reflection_response::MessageResponse;
+use tonic_reflection::pb::ServerReflectionRequest;
+
+pub async fn fill_pool_from_files(paths: Vec<PathBuf>) -> Result<DescriptorPool, String> {
+    let mut pool = DescriptorPool::new();
+    let random_file_name = format!("{}.desc", uuid::Uuid::new_v4());
+    let desc_path = temp_dir().join(random_file_name);
+    let bin = protoc_bin_vendored::protoc_bin_path().unwrap();
+
+    let mut cmd = Command::new(bin.clone());
+    cmd.arg("--include_imports")
+        .arg("--include_source_info")
+        .arg("-o")
+        .arg(&desc_path);
+
+    for p in paths {
+        if p.as_path().exists() {
+            cmd.arg(p.as_path().to_string_lossy().as_ref());
+        } else {
+            continue;
+        }
+
+        let parent = p.as_path().parent();
+        if let Some(parent_path) = parent {
+            cmd.arg("-I").arg(parent_path);
+            cmd.arg("-I").arg(parent_path.parent().unwrap());
+        } else {
+            debug!("ignoring {:?} since it does not exist.", parent)
+        }
+    }
+
+    let output = cmd.output().map_err(|e| e.to_string())?;
+    if !output.status.success() {
+        return Err(format!(
+            "protoc failed: {}",
+            String::from_utf8_lossy(&output.stderr)
+        ));
+    }
+
+    let bytes = fs::read(desc_path.as_path())
+        .await
+        .map_err(|e| e.to_string())?;
+    let fdp = FileDescriptorSet::decode(bytes.deref()).map_err(|e| e.to_string())?;
+    pool.add_file_descriptor_set(fdp)
+        .map_err(|e| e.to_string())?;
+
+    fs::remove_file(desc_path.as_path())
+        .await
+        .map_err(|e| e.to_string())?;
+
+    Ok(pool)
+}
+
+pub async fn fill_pool(uri: &Uri) -> Result<DescriptorPool, String> {
+    let mut pool = DescriptorPool::new();
+    let mut client = ServerReflectionClient::with_origin(get_transport(), uri.clone());
+
+    for service in list_services(&mut client).await? {
+        if service == "grpc.reflection.v1alpha.ServerReflection" {
+            continue;
+        }
+        file_descriptor_set_from_service_name(&service, &mut pool, &mut client).await;
+    }
+
+    Ok(pool)
+}
+
+pub fn get_transport() -> Client<HttpsConnector<HttpConnector>, BoxBody> {
+    let connector = HttpsConnectorBuilder::new().with_native_roots();
+    let connector = connector.https_or_http().enable_http2().wrap_connector({
+        let mut http_connector = HttpConnector::new();
+        http_connector.enforce_http(false);
+        http_connector
+    });
+    Client::builder()
+        .pool_max_idle_per_host(0)
+        .http2_only(true)
+        .build(connector)
+}
+
+async fn list_services(
+    reflect_client: &mut ServerReflectionClient<Client<HttpsConnector<HttpConnector>, BoxBody>>,
+) -> Result<Vec<String>, String> {
+    let response =
+        send_reflection_request(reflect_client, MessageRequest::ListServices("".into())).await?;
+
+    let list_services_response = match response {
+        MessageResponse::ListServicesResponse(resp) => resp,
+        _ => panic!("Expected a ListServicesResponse variant"),
+    };
+
+    Ok(list_services_response
+        .service
+        .iter()
+        .map(|s| s.name.clone())
+        .collect::<Vec<_>>())
+}
+
+async fn file_descriptor_set_from_service_name(
+    service_name: &str,
+    pool: &mut DescriptorPool,
+    client: &mut ServerReflectionClient<Client<HttpsConnector<HttpConnector>, BoxBody>>,
+) {
+    let response = match send_reflection_request(
+        client,
+        MessageRequest::FileContainingSymbol(service_name.into()),
+    )
+    .await
+    {
+        Ok(resp) => resp,
+        Err(e) => {
+            warn!(
+                "Error fetching file descriptor for service {}: {}",
+                service_name, e
+            );
+            return;
+        }
+    };
+
+    let file_descriptor_response = match response {
+        MessageResponse::FileDescriptorResponse(resp) => resp,
+        _ => panic!("Expected a FileDescriptorResponse variant"),
+    };
+
+    for fd in file_descriptor_response.file_descriptor_proto {
+        let fdp = FileDescriptorProto::decode(fd.deref()).unwrap();
+
+        // Add deps first or else we'll get an error
+        for dep_name in fdp.clone().dependency {
+            file_descriptor_set_by_filename(&dep_name, pool, client).await;
+        }
+
+        pool.add_file_descriptor_proto(fdp)
+            .expect("add file descriptor proto");
+    }
+}
+
+async fn file_descriptor_set_by_filename(
+    filename: &str,
+    pool: &mut DescriptorPool,
+    client: &mut ServerReflectionClient<Client<HttpsConnector<HttpConnector>, BoxBody>>,
+) {
+    // We already fetched this file
+    if let Some(_) = pool.get_file_by_name(filename) {
+        return;
+    }
+
+    let response =
+        send_reflection_request(client, MessageRequest::FileByFilename(filename.into())).await;
+    let file_descriptor_response = match response {
+        Ok(MessageResponse::FileDescriptorResponse(resp)) => resp,
+        Ok(_) => {
+            panic!("Expected a FileDescriptorResponse variant")
+        }
+        Err(e) => {
+            warn!("Error fetching file descriptor for {}: {}", filename, e);
+            return;
+        }
+    };
+
+    for fd in file_descriptor_response.file_descriptor_proto {
+        let fdp = FileDescriptorProto::decode(fd.deref()).unwrap();
+        pool.add_file_descriptor_proto(fdp)
+            .expect("add file descriptor proto");
+    }
+}
+
+async fn send_reflection_request(
+    client: &mut ServerReflectionClient<Client<HttpsConnector<HttpConnector>, BoxBody>>,
+    message: MessageRequest,
+) -> Result<MessageResponse, String> {
+    let reflection_request = ServerReflectionRequest {
+        host: "".into(), // Doesn't matter
+        message_request: Some(message),
+    };
+
+    let request = Request::new(tokio_stream::once(reflection_request));
+
+    client
+        .server_reflection_info(request)
+        .await
+        .map_err(|e| match e.code() {
+            tonic::Code::Unavailable => "Failed to connect to endpoint".to_string(),
+            tonic::Code::Unauthenticated => "Authentication failed".to_string(),
+            tonic::Code::DeadlineExceeded => "Deadline exceeded".to_string(),
+            _ => e.to_string(),
+        })?
+        .into_inner()
+        .next()
+        .await
+        .expect("steamed response")
+        .map_err(|e| e.to_string())?
+        .message_response
+        .ok_or("No reflection response".to_string())
+}
+
+pub fn method_desc_to_path(md: &MethodDescriptor) -> PathAndQuery {
+    let full_name = md.full_name();
+    let (namespace, method_name) = full_name
+        .rsplit_once('.')
+        .ok_or_else(|| anyhow!("invalid method path"))
+        .expect("invalid method path");
+    PathAndQuery::from_str(&format!("/{}/{}", namespace, method_name)).expect("invalid method path")
+}