Files
voice-cat/server/src/media_relay.h
Talon 694494a5be feat(M2): UDP voice/media plane -- SFU relay, Opus, AEAD, jitter buffer
Adds the full voice pipeline: 14-byte binary frame header, ChaCha20-Poly1305
AEAD keyed from the TLS exporter, libopus encode/decode with FEC/PLC/DTX,
an adaptive per-ssrc jitter buffer, a miniaudio capture/playback engine, an
APM passthrough stub, and the UdpBinding/StreamAnnounce signaling chain
wired through ConnSession/SessionRegistry into a new server-side SFU
(MediaRelay) that decrypts and re-encrypts frames per channel member.

Exit criterion verified: test_m2_voice — two headless clients relay 50
encrypted Opus frames through the server; ctest --preset m1-dev is 9/9
green. Also corrects protocol.md's UdpBinding diagram, which described the
UDP-side binding packet as AEAD-sealed when it is in fact a plaintext
bootstrap frame (separate from the TCP/TLS UdpBinding ack).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-06-16 01:31:14 +02:00

66 lines
2.0 KiB
C++

/*
* server/media_relay.h — UDP SFU relay for M2 voice.
*
* Design: docs/architecture.md §5, docs/voice.md §2.
* Receives encrypted UDP voice frames from clients, decrypts+authenticates them,
* re-encrypts for each channel member, and forwards.
*
* Flow:
* 1. Client sends kFrameUdpBinding UDP packet (plaintext) → MediaRelay looks up
* the 16-byte token in SessionRegistry, associates the sender endpoint with
* the ConnSession, and calls session->set_udp_endpoint().
* 2. Client sends kFrameVoice UDP packets → MediaRelay decrypts via recv_crypto(),
* finds channel members via find_channel_sessions(), re-encrypts via send_crypto(),
* and sends to each member's UDP endpoint.
*/
#ifndef VOICECAT_SERVER_MEDIA_RELAY_H
#define VOICECAT_SERVER_MEDIA_RELAY_H
#ifdef VOICECAT_HAS_NET
#include <memory>
#define ASIO_STANDALONE 1
#include <asio.hpp>
#include "net/transport.h"
namespace voicecat::server {
class SessionRegistry;
class MediaRelay {
public:
MediaRelay(asio::io_context& io, std::shared_ptr<SessionRegistry> registry);
~MediaRelay();
// Bind the UDP socket. port=0 lets the OS pick. Must be called before start().
bool bind(uint16_t port = 0);
// Begin async receive loop. Call once after bind().
void start();
// Stop receiving and close the socket.
void stop();
// Actual bound port (after bind()).
uint16_t media_port() const;
private:
void on_udp_frame(const uint8_t* data, size_t len, asio::ip::udp::endpoint sender);
asio::io_context& io_;
std::shared_ptr<SessionRegistry> registry_;
voicecat::net::UdpMediaChannel udp_;
// Scratch buffer for re-encrypted payloads (size = max_frame + 16 MAC)
static constexpr size_t kMaxPayload = 1500;
std::vector<uint8_t> seal_buf_ = std::vector<uint8_t>(kMaxPayload + 16, uint8_t{0});
std::vector<uint8_t> plain_buf_ = std::vector<uint8_t>(kMaxPayload, uint8_t{0});
};
} // namespace voicecat::server
#endif // VOICECAT_HAS_NET
#endif // VOICECAT_SERVER_MEDIA_RELAY_H