When the user passes --bind <iface> and doesn't set --interface,
discovery now reuses the same interface name instead of auto-picking.
Common single-interface setups stop needing to repeat the flag, while
the two flags remain independent for the cases that legitimately want
HTTP and discovery on different interfaces.
Update the --interface help text to document the default. The --bind
text is unchanged: it still describes the HTTP listener address.
Refs #264
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
The previous implementation silently returned the literal interface
name when the interface existed but had no IPv4 address (or when
listing addresses failed). That reproduces the exact error from #264
("listen tcp: lookup eth103 on ...: no such host") for users on
IPv6-only or admin-down interfaces, so the fix only worked for the
happy path.
Return an explicit error for those cases and fatal in main with a
message that identifies the offending --bind value. Add an IPv6
fallback (single non-link-local address, bracketed) and treat any
ambiguity -- multiple IPv4 or multiple IPv6 addresses on the same
interface -- as an error rather than picking one silently. Log when an
interface name was resolved to an IP so the indirection is visible.
Update the --bind flag help text to reflect the supported inputs.
Add a test covering the pass-through cases (host, IP, empty, unknown
name) and a portable loopback-interface test that skips cleanly when
the loopback isn't in a single-IPv4 configuration.
Refs #264
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
On a multi-homed host the discovery layer used to walk net.Interfaces()
and pick the first non-loopback IPv4 NIC, while UPnP/SSDP bound a
wildcard UDP socket and let the kernel route the multicast send. That
meant --bind on soundtouch-web only moved the HTTP listener; the
discovery still went out whatever interface the kernel preferred (often
the wrong one on hosts where the speakers sit behind a secondary NIC).
Introduce a separate DiscoveryInterface knob:
* pkg/config: DiscoveryInterface field + DISCOVERY_INTERFACE env var.
* pkg/discovery/mdns: NewMDNSDiscoveryServiceWithInterface; the
interface resolver now honours an explicit name and validates it
has a usable IPv4 address before handing it to hashicorp/mdns.
* pkg/discovery/upnp: when an interface is configured, bind the UDP
socket's source IP to the NIC's IPv4 and call
ipv4.PacketConn.SetMulticastInterface so M-SEARCH leaves the right
NIC. Without an interface, behaviour is unchanged.
* cmd/soundtouch-web: new --interface flag (DISCOVERY_INTERFACE env)
plumbed into the config before the discovery service is built.
go.mod/go.sum reflect promoting golang.org/x/net from indirect to a
direct dependency (now imported for ipv4.PacketConn).
Refs #264.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
The flag's value is concatenated with ":PORT" and passed to
http.ListenAndServe, so it has always been a host/IP. The previous help
text invited users to pass an interface name like "eth0", which then
failed with a confusing DNS lookup error.
Refs #264.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Tobias GesellchenandClaude Opus 4.7
mehmet turac