Add artmap polling to discover sACN unicast receivers

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

artmap.go

@@ -0,0 +1,117 @@
+package tendrils
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+	"net"
+	"net/http"
+	"strings"
+	"time"
+)
+
+type artmapConfig struct {
+	Targets  []artmapTarget  `json:"targets"`
+	Mappings []artmapMapping `json:"mappings"`
+}
+
+type artmapTarget struct {
+	Universe artmapUniverse `json:"universe"`
+	Address  string         `json:"address"`
+}
+
+type artmapMapping struct {
+	From artmapFromAddr `json:"from"`
+	To   artmapToAddr   `json:"to"`
+}
+
+type artmapUniverse struct {
+	Protocol string `json:"protocol"`
+	Number   uint16 `json:"number"`
+}
+
+type artmapFromAddr struct {
+	Universe     artmapUniverse `json:"universe"`
+	ChannelStart int            `json:"channel_start"`
+	ChannelEnd   int            `json:"channel_end"`
+}
+
+type artmapToAddr struct {
+	Universe     artmapUniverse `json:"universe"`
+	ChannelStart int            `json:"channel_start"`
+}
+
+var artmapClient = &http.Client{Timeout: 2 * time.Second}
+
+func (t *Tendrils) probeArtmap(ip net.IP) {
+	url := fmt.Sprintf("http://%s:8080/api/config", ip)
+
+	resp, err := artmapClient.Get(url)
+	if err != nil {
+		return
+	}
+	defer resp.Body.Close()
+
+	server := resp.Header.Get("Server")
+	if server != "artmap" {
+		if server != "" {
+			log.Printf("[artmap] unexpected server header ip=%s server=%q", ip, server)
+		}
+		return
+	}
+
+	var cfg artmapConfig
+	if err := json.NewDecoder(resp.Body).Decode(&cfg); err != nil {
+		log.Printf("[artmap] decode error ip=%s: %v", ip, err)
+		return
+	}
+
+	log.Printf("[artmap] found ip=%s targets=%d mappings=%d", ip, len(cfg.Targets), len(cfg.Mappings))
+
+	t.processArtmapConfig(&cfg)
+}
+
+func (t *Tendrils) processArtmapConfig(cfg *artmapConfig) {
+	updated := false
+	for _, target := range cfg.Targets {
+		ip := parseTargetIP(target.Address)
+		if ip == nil {
+			log.Printf("[artmap] failed to parse target address %q", target.Address)
+			continue
+		}
+
+		node := t.nodes.GetByIP(ip)
+		if node == nil {
+			log.Printf("[artmap] target ip=%s not found as node", ip)
+			continue
+		}
+
+		universe := int(target.Universe.Number)
+		switch target.Universe.Protocol {
+		case "artnet":
+			t.nodes.UpdateArtNet(node, []int{universe}, nil)
+			log.Printf("[artmap] marked %s (%s) as artnet input for universe %d", node.DisplayName(), ip, universe)
+		case "sacn":
+			t.nodes.UpdateSACNUnicastInputs(node, []int{universe})
+			log.Printf("[artmap] marked %s (%s) as sacn input for universe %d", node.DisplayName(), ip, universe)
+		default:
+			log.Printf("[artmap] unknown protocol %q for target %s", target.Universe.Protocol, target.Address)
+			continue
+		}
+		updated = true
+	}
+	if updated {
+		t.NotifyUpdate()
+	}
+}
+
+func parseTargetIP(addr string) net.IP {
+	host := addr
+	if idx := strings.LastIndex(addr, ":"); idx != -1 {
+		h, _, err := net.SplitHostPort(addr)
+		if err == nil {
+			host = h
+		}
+	}
+	return net.ParseIP(host)
+}