hygate-c

A small, dependency-light C port of the Hygate gateway that exposes a Gradio-hosted Hunyuan model (hy3) behind an OpenAI-compatible REST API.

It translates OpenAI chat/completions requests into Gradio's queue API (POST /gradio_api/call/chat → GET /gradio_api/call/chat/{event_id} SSE stream) and translates the Gradio stream back into OpenAI streaming and non-streaming responses, including tool calls and reasoning content.

Build

Requires libcurl and json-c (auto-detected via pkg-config); falls back to -lcurl -ljson-c if pkg-config is unavailable.

make            # dynamic binary -> bin/hygate
make static     # static binary  -> bin/hygate.static
make clean

Build is POSIX-portable (Linux, FreeBSD, macOS) and compiles clean with -Wall -Wextra.

Run

./bin/hygate [options]

Options

Flag	Default	Description
`-port <n>`	`8080`	Listen port (binds `0.0.0.0`).
`-endpoint <url>`	`https://tencent-hy3.hf.space`	Upstream Gradio Space base URL (trailing slash trimmed).
`-model <name>`	`hy3`	Model name reported in `/v1/models` and responses.
`-user-agent <ua>` / `-ua <ua>`	built-in Firefox UA	Outgoing `User-Agent`. Empty string => default.
`-max-body <bytes>`	`5242880` (5 MiB)	Maximum request body size. Oversized requests are rejected with `413`.
`-max-conn <n>`	`16`	Maximum concurrent connections (worker threads). Excess connections queue in the kernel listen backlog.

Flag forms: -key value or -key=value.

Example — listen on 9090, allow 8 MiB bodies, cap at 32 concurrent connections:

./bin/hygate -port 9090 -max-body 8388608 -max-conn 32

Endpoints

Method	Path	Notes
`GET`	`/v1/models`, `/models`	Returns the configured model (served locally, no upstream call).
`POST`	`/v1/chat/completions`, `/chat/completions`	OpenAI-style chat completion. Supports `stream`, `tools`/`tool_calls`, and `reasoning_content`.
`OPTIONS`	any of the above	CORS preflight.

CORS is enabled for all origins (Access-Control-Allow-Origin: *).

Request / response notes

OpenAI messages are mapped into Gradio's [message, system, history, "high", temperature, max_tokens, top_p, null, functions_json] payload.
max_tokens / max_completion_tokens are honored; defaults to 131072 when omitted.
Upstream calls use Fibonacci-backoff retries (up to MAX_RETRIES = 5, 300 s timeout).

Security considerations

The server binds all interfaces (0.0.0.0) and currently enforces no authentication — it is an open relay to the configured upstream. Do not expose it to untrusted networks without a fronting proxy or auth layer.
-max-body and -max-conn exist to bound resource usage (memory and thread count) against abusive clients.

Source layout

File	Role
`main.c`	Entry point, flag parsing, TCP listen, thread-per-connection with concurrency cap.
`server.c`	HTTP parsing, routing, SSE emitters, libcurl upstream calls, streaming state machine.
`jsonapi.c`	OpenAI <-> Gradio payload translation and stream parsing.
`util.c`	Growable string buffer (`strbuf`), UUID, backoff, helpers.
`hygate.h`	Shared types and declarations.

Credits

Created by Luxferre in 2026, released into the public domain with no warranties.