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// WebSocket Handler Module
// Implements WebSocket transport for the OpenAI Responses API.
// Reference: https://platform.openai.com/docs/guides/websocket-mode
use super::handlers::{generate_responses_result, ResponseGenerationParams};
use super::state::AppState;
use crate::openai::websocket::{ClientEvent, ServerEvent};
use crate::openai::ResponsesResponse;
use crate::{EndpointType, ErrorInjector, ResponsesTokenStreamBuilder};
use axum::extract::ws::{Message, WebSocket};
use axum::extract::{State, WebSocketUpgrade};
use axum::response::Response;
use futures_util::StreamExt;
use std::sync::Arc;
use std::time::{Duration, Instant};
/// Maximum connection duration (60 minutes)
const MAX_CONNECTION_DURATION: Duration = Duration::from_secs(60 * 60);
/// GET /openai/v1/responses (WebSocket upgrade)
pub async fn ws_responses(ws: WebSocketUpgrade, State(state): State<Arc<AppState>>) -> Response {
tracing::info!("WebSocket connection upgrade request");
ws.on_upgrade(move |socket| handle_ws_connection(socket, state))
}
/// Handle a single WebSocket connection lifecycle.
async fn handle_ws_connection(mut socket: WebSocket, state: Arc<AppState>) {
let connection_start = Instant::now();
state.stats.record_ws_connect();
tracing::info!("WebSocket connection established");
// Connection-local cache: the most recent completed response
let mut cached_response: Option<ResponsesResponse> = None;
loop {
// Check connection timeout
if connection_start.elapsed() >= MAX_CONNECTION_DURATION {
let event = ServerEvent::connection_limit_reached();
let _ = socket
.send(Message::Text(serde_json::to_string(&event).unwrap().into()))
.await;
break;
}
// Wait for next message with a timeout aligned to the remaining connection time
let remaining = MAX_CONNECTION_DURATION.saturating_sub(connection_start.elapsed());
let msg = tokio::time::timeout(remaining, socket.recv()).await;
let msg = match msg {
Ok(Some(Ok(msg))) => msg,
Ok(Some(Err(e))) => {
tracing::warn!("WebSocket receive error: {}", e);
break;
}
Ok(None) => {
// Client disconnected
tracing::info!("WebSocket client disconnected");
break;
}
Err(_) => {
// Connection timeout
let event = ServerEvent::connection_limit_reached();
let _ = socket
.send(Message::Text(serde_json::to_string(&event).unwrap().into()))
.await;
break;
}
};
match msg {
Message::Text(text) => {
let event = match serde_json::from_str::<ClientEvent>(&text) {
Ok(event) => event,
Err(e) => {
let error = ServerEvent::invalid_request(&format!(
"Failed to parse message: {}",
e
));
let _ = socket
.send(Message::Text(serde_json::to_string(&error).unwrap().into()))
.await;
continue;
}
};
match event {
ClientEvent::ResponseCreate { response: body } => {
// Validate previous_response_id if provided
if let Some(ref prev_id) = body.previous_response_id {
let cached_id = cached_response.as_ref().map(|r| r.id.as_str());
if cached_id != Some(prev_id.as_str()) {
let error = ServerEvent::previous_response_not_found(prev_id);
let _ = socket
.send(Message::Text(
serde_json::to_string(&error).unwrap().into(),
))
.await;
// Failed turn evicts cached response
cached_response = None;
continue;
}
}
// Handle generate=false (warmup/pre-loading)
if !body.generate {
tracing::info!(
model = %body.model,
"WebSocket warmup request (generate=false)"
);
// Acknowledge with a minimal response.created event
let warmup_response = ResponsesResponse::warmup(body.model.clone());
let event = serde_json::json!({
"type": "response.created",
"response": warmup_response
});
let _ = socket
.send(Message::Text(serde_json::to_string(&event).unwrap().into()))
.await;
continue;
}
let request_start = Instant::now();
tracing::info!(
model = %body.model,
"WebSocket response.create"
);
// Record request start
state.stats.record_request_start(
&body.model,
true, // WS is always streaming
EndpointType::WebSocketResponses,
);
// Check for error injection
let error_injector = ErrorInjector::new(state.config.error_config());
if let Some(error) = error_injector.maybe_inject() {
tracing::warn!("Injecting error on WebSocket: {:?}", error);
state.stats.record_error(error.status_code());
let err_resp = error.to_error_response();
let error_event = ServerEvent::from_error(
&err_resp.error.error_type,
&err_resp.error.message,
);
let _ = socket
.send(Message::Text(
serde_json::to_string(&error_event).unwrap().into(),
))
.await;
cached_response = None;
continue;
}
// Generate response using shared logic
let result = generate_responses_result(
&state,
&ResponseGenerationParams {
model: &body.model,
input: &body.input,
instructions: &body.instructions,
temperature: body.temperature,
top_p: body.top_p,
max_output_tokens: body.max_output_tokens,
reasoning: &body.reasoning,
},
);
// Build the streaming response
let stats = state.stats.clone();
let input_tok = result.usage.input_tokens;
let output_tok = result.usage.output_tokens;
let mut builder =
ResponsesTokenStreamBuilder::new(&body.model, result.content)
.latency(result.latency)
.usage(result.usage)
.on_complete(move || {
stats.record_request_end(
request_start.elapsed(),
input_tok,
output_tok,
);
});
if result.reasoning_tokens > 0 {
builder = builder.reasoning(result.reasoning_summary);
}
let stream = builder.build();
// Stream events over WebSocket as JSON text frames.
// The existing stream produces SSE-formatted strings;
// we extract the JSON payload from each SSE chunk.
let mut sse_stream = stream.into_stream();
let mut last_completed_response: Option<ResponsesResponse> = None;
while let Some(sse_chunk) = sse_stream.next().await {
if let Some(json_str) = extract_json_from_sse(&sse_chunk) {
// Capture the completed response for caching
if sse_chunk.contains("response.completed") {
if let Ok(parsed) =
serde_json::from_str::<serde_json::Value>(json_str)
{
if let Some(resp) = parsed.get("response") {
if let Ok(response) =
serde_json::from_value::<ResponsesResponse>(
resp.clone(),
)
{
last_completed_response = Some(response);
}
}
}
}
if socket
.send(Message::Text(json_str.to_string().into()))
.await
.is_err()
{
tracing::warn!("Failed to send WS frame, client disconnected");
break;
}
}
}
// Update connection-local cache
cached_response = last_completed_response;
}
}
}
Message::Close(_) => {
tracing::info!("WebSocket close frame received");
break;
}
Message::Ping(data) => {
let _ = socket.send(Message::Pong(data)).await;
}
_ => {
// Ignore binary frames, pong frames
}
}
}
state.stats.record_ws_disconnect();
tracing::info!(
duration_secs = connection_start.elapsed().as_secs(),
"WebSocket connection closed"
);
}
/// Extract the JSON payload from an SSE-formatted string.
/// SSE format: `event: <type>\ndata: <json>\n\n`
fn extract_json_from_sse(sse: &str) -> Option<&str> {
for line in sse.lines() {
if let Some(data) = line.strip_prefix("data: ") {
return Some(data.trim());
}
}
None
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_extract_json_from_sse() {
let sse = "event: response.created\ndata: {\"type\":\"response.created\"}\n\n";
let json = extract_json_from_sse(sse).unwrap();
assert_eq!(json, "{\"type\":\"response.created\"}");
}
#[test]
fn test_extract_json_from_sse_no_data() {
let sse = "event: response.created\n\n";
assert!(extract_json_from_sse(sse).is_none());
}
#[test]
fn test_extract_json_from_sse_empty() {
assert!(extract_json_from_sse("").is_none());
}
}