Implement Mihomo external-controller support in configuration and gateway

- Added optional Mihomo configuration fields in `config.compose.yaml` and `config.example.yaml` for enhanced integration with the Mihomo external-controller.
- Updated the `Gateway` to handle Mihomo API requests, including proxying and error handling for Mihomo-specific endpoints.
- Enhanced the documentation in `GATEWAY_RUN.md` to guide users on configuring Mihomo integration.
- Introduced new utility functions in the web client for interacting with Mihomo API endpoints, improving the overall user experience.
- Updated the sidebar in the Svelte components to include a link to the Mihomo section, enhancing navigation.

internal/server/gateway.go

@@ -24,6 +24,7 @@ import (
 type Gateway struct {
 	parsed        *config.Parsed
 	proxies       map[string]http.Handler
+	mihomo        map[string]http.Handler
 	agg           *aggregate.Handler
 	geo           *geoip.Service
 	log           *slog.Logger
@@ -45,6 +46,7 @@ func NewGateway(p *config.Parsed, log *slog.Logger, geo *geoip.Service) (*Gatewa
 	g := &Gateway{
 		parsed:      p,
 		proxies:     make(map[string]http.Handler),
+		mihomo:      make(map[string]http.Handler),
 		geo:         geo,
 		log:         log,
 		transport:   t,
@@ -68,6 +70,19 @@ func NewGateway(p *config.Parsed, log *slog.Logger, geo *geoip.Service) (*Gatewa
 			})
 		})
 	}
+	for alias, m := range p.MihomoByAlias {
+		a := alias
+		strip := "/api/" + a + "/mihomo"
+		g.mihomo[a] = proxy.NewMihomoForward(m.Base, strip, m.Auth, t, func(w http.ResponseWriter, r *http.Request, err error) {
+			log.Error("mihomo upstream error", "alias", a, "err", err)
+			w.Header().Set("Content-Type", "application/json; charset=utf-8")
+			w.WriteHeader(http.StatusBadGateway)
+			_ = json.NewEncoder(w).Encode(map[string]any{
+				"ok":    false,
+				"error": map[string]string{"code": "bad_gateway", "message": "mihomo upstream unreachable"},
+			})
+		})
+	}
 	var aggCacheTTL time.Duration
 	if p.Config.Aggregate != nil && p.Config.Aggregate.CacheTTLMs > 0 {
 		aggCacheTTL = time.Duration(p.Config.Aggregate.CacheTTLMs) * time.Millisecond
@@ -230,7 +245,11 @@ func routeEndpoint(path string) string {
 		if i < 0 {
 			return "proxy_root"
 		}
-		return "proxy_" + rest[i+1:]
+		sub := rest[i+1:]
+		if strings.HasPrefix(sub, "mihomo/") {
+			return "mihomo_" + sub[len("mihomo/"):]
+		}
+		return "proxy_" + sub
 	}
 	return "ui"
 }
@@ -285,7 +304,7 @@ func (g *Gateway) serve(w http.ResponseWriter, r *http.Request) {
 		http.NotFound(w, r)
 		return
 	}
-	rp, ok := g.proxies[alias]
+	_, ok := g.proxies[alias]
 	if !ok {
 		w.Header().Set("Content-Type", "application/json; charset=utf-8")
 		w.WriteHeader(http.StatusNotFound)
@@ -295,7 +314,28 @@ func (g *Gateway) serve(w http.ResponseWriter, r *http.Request) {
 		})
 		return
 	}
-	rp.ServeHTTP(w, r)
+	mihomoPfx := "/api/" + alias + "/mihomo"
+	if strings.HasPrefix(r.URL.Path, mihomoPfx) {
+		mh, have := g.mihomo[alias]
+		if !have {
+			proxy.MihomoJSONError(w, "mihomo_not_configured", "mihomo is not configured for this server")
+			return
+		}
+		if r.URL.Path == mihomoPfx+"/meta" && r.Method == http.MethodGet {
+			mu := g.parsed.MihomoByAlias[alias]
+			if mu == nil {
+				proxy.MihomoJSONError(w, "mihomo_not_configured", "mihomo is not configured for this server")
+				return
+			}
+			w.Header().Set("Content-Type", "application/json; charset=utf-8")
+			w.WriteHeader(http.StatusOK)
+			_, _ = w.Write(proxy.MihomoMetaJSON(mu.Base))
+			return
+		}
+		mh.ServeHTTP(w, r)
+		return
+	}
+	g.proxies[alias].ServeHTTP(w, r)
 }
 
 func (g *Gateway) serveLiveEvents(w http.ResponseWriter, r *http.Request) {