feat(cast): Chromecast mDNS discovery - #75
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internal/cast/mdns.go browses for _googlecast._tcp devices and assembles each from its PTR/SRV/TXT/A records, accumulating records that mDNS splits across packets. Wires chromecastProvider.Discover to it (Play/ Stop/Status still stubbed -- the control channel is the next commit). Self-contained: a small hand-written DNS-SD query and wire parser (name compression, pointer-loop guard, oversize guards) rather than a general mDNS module -- the query is one fixed PTR and the needed record types are few. Avoids pulling github.com/hashicorp/mdns + github.com/miekg/dns + golang.org/x/net, which also bumped x/net and x/text project-wide. Tests use hand-built DNS packets: single-packet assembly, cross-packet accumulation, compression-pointer following, pointer-loop rejection. No new dependencies. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01JBJdG8Qenand5i16WT6BHG
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Updated: the initial implementation only listened on an ephemeral unicast port, so it caught almost nothing on a real network (mDNS responders answer via multicast, and a system mDNS daemon like avahi holding :5353 means the kernel may not hand us the multicast traffic). Now: a dedicated ephemeral unicast socket sends the query with the unicast-response (QU) bit set (first reply comes straight back to us), plus the 224.0.0.251:5353 group joined per interface (a host with docker0 alongside wlan otherwise joins the wrong one), plus the query re-sent twice more (mDNS is lossy). SRV/TXT records are now filtered to Verified against a live network: 7/7 real Cast devices found with id/name/model, consistently across runs. Still no new dependencies. |
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Stacked on the castproto PR.
internal/cast/mdns.gobrowses_googlecast._tcpand assembles each device from its PTR/SRV/TXT/A records, accumulating records mDNS splits across packets. WireschromecastProvider.Discover.Deviation from the plan: hand-written DNS-SD query + wire parser (name compression, pointer-loop guard) instead of
github.com/hashicorp/mdns— that dep also pullsmiekg/dns+golang.org/x/netand bumpedx/net/x/textproject-wide. The query is one fixed PTR; few record types needed.Tests use hand-built DNS packets. No new dependencies.