fegger
7be8d59d07
Add mDNS/DNS-SD discovery and JSON session negotiation so two peers on a LAN connect without hard-coded addresses. - Discovery (Avahi threaded-poll client): the receiver announces _screencast._tcp with its signaling port; senders browse and resolve peers. Strict lock ordering (poll lock before state mutex) keeps the callbacks deadlock-free; name collisions rename via avahi_alternative_service_name. - Signaling: one JSON object per newline-terminated TCP line. The receiver hosts a server (port 5005) and answers session offers with its RTP port; senders connect, offer, and stream to the negotiated endpoint. WebSocket was deferred: no WS library is installed, the skill permits plain TCP, and the wire format is transport-agnostic. - Dual-stack transports: this machine resolves its own services over IPv6, so getaddrinfo now runs AF_UNSPEC and listeners bind IPv6 with IPV6_V6ONLY=0 (IPv4 fallback), covering UDP and TCP alike. The signaling client shutdown now uses shutdown() so a reader blocked in recv() cannot hang the join (a plain close() does not wake it). - CLI: --discover lists receivers (deduped to one entry per host); --send auto-disovers when exactly one receiver is found; --peer targets a receiver directly; --signaling-port overrides the default. Validation: meson test 5/5 (new signaling round-trip test), valgrind clean. End-to-end over loopback: --discover finds the announced receiver, a probe negotiated a session and streamed 60 frames over both IPv4 and IPv6, and the receiver reported stream started. mDNS resolution was verified against avahi-browse as an independent reference.
59 lines
1.8 KiB
C++
59 lines
1.8 KiB
C++
#pragma once
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#include "screencast/network/error.h"
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#include "screencast/network/transport.h"
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#include <cstdint>
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#include <functional>
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#include <memory>
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#include <string>
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#include <variant>
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namespace sc {
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// JSON-based control messages exchanged before or during a session. The wire
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// format is one JSON object per newline-terminated TCP line; a WebSocket
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// transport can replace TCP in a later phase without changing these types.
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struct SessionOffer {
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std::string session_id;
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std::string codec_name;
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int width = 0; // informational; the stream carries its own SPS/PPS
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int height = 0;
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int frame_rate_num = 30;
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int frame_rate_den = 1;
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Endpoint rtp_endpoint; // unused by the receiver; kept for symmetry
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};
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struct SessionAnswer {
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std::string session_id;
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// The address may be empty: the sender then targets the address of its
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// signaling connection and the port carried here.
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Endpoint rtp_endpoint;
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};
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using SignalingMessage = std::variant<SessionOffer, SessionAnswer>;
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class SignalingChannel {
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public:
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using MessageCallback = std::function<void(const SignalingMessage&)>;
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virtual ~SignalingChannel() = default;
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// Client channels connect to a receiver's signaling server.
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virtual bool connect(const Endpoint& server) = 0;
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virtual void send(const SignalingMessage& message) = 0;
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virtual void on_message(MessageCallback callback) = 0;
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virtual void disconnect() = 0;
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};
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class SignalingFactory {
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public:
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// A client channel that connects to a receiver's signaling server.
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static NetworkResult<std::unique_ptr<SignalingChannel>> create_client();
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// A server channel listening on the given port; it keeps the most
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// recent connection as its active peer.
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static NetworkResult<std::unique_ptr<SignalingChannel>> create_server(uint16_t port);
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};
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} // namespace sc
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