Plugin assets, external scripts and CSP overrides (#4260)

* Add assets for plugins
* Move plugin javascript and css into separate endpoints
* Allow loading external scripts
* Add csp overrides
* Only include enabled plugins
* Move URLMap to utils
* Use URLMap for assets
* Add documentation

graphql/documents/queries/plugins.graphql

@@ -24,6 +24,11 @@ query Plugins {
       description
       type
     }
+
+    paths {
+      css
+      javascript
+    }
   }
 }
 

graphql/schema/types/plugin.graphql

@@ -1,3 +1,10 @@
+type PluginPaths {
+  # path to javascript files
+  javascript: [String!]
+  # path to css files
+  css: [String!]
+}
+
 type Plugin {
   id: ID!
   name: String!
@@ -10,6 +17,8 @@ type Plugin {
   tasks: [PluginTask!]
   hooks: [PluginHook!]
   settings: [PluginSetting!]
+
+  paths: PluginPaths!
 }
 
 type PluginTask {

internal/api/context_keys.go

@@ -13,4 +13,5 @@ const (
 	tagKey
 	downloadKey
 	imageKey
+	pluginKey
 )

internal/api/resolver.go

@@ -84,6 +84,9 @@ func (r *Resolver) Tag() TagResolver {
 func (r *Resolver) SavedFilter() SavedFilterResolver {
 	return &savedFilterResolver{r}
 }
+func (r *Resolver) Plugin() PluginResolver {
+	return &pluginResolver{r}
+}
 func (r *Resolver) ConfigResult() ConfigResultResolver {
 	return &configResultResolver{r}
 }
@@ -102,6 +105,7 @@ type studioResolver struct{ *Resolver }
 type movieResolver struct{ *Resolver }
 type tagResolver struct{ *Resolver }
 type savedFilterResolver struct{ *Resolver }
+type pluginResolver struct{ *Resolver }
 type configResultResolver struct{ *Resolver }
 
 func (r *Resolver) withTxn(ctx context.Context, fn func(ctx context.Context) error) error {

internal/api/resolver_model_plugin.go

@@ -0,0 +1,57 @@
+package api
+
+import (
+	"context"
+
+	"github.com/stashapp/stash/pkg/plugin"
+)
+
+type pluginURLBuilder struct {
+	BaseURL string
+	Plugin  *plugin.Plugin
+}
+
+func (b pluginURLBuilder) javascript() []string {
+	ui := b.Plugin.UI
+	if len(ui.Javascript) == 0 && len(ui.ExternalScript) == 0 {
+		return nil
+	}
+
+	var ret []string
+
+	ret = append(ret, ui.ExternalScript...)
+	ret = append(ret, b.BaseURL+"/plugin/"+b.Plugin.ID+"/javascript")
+
+	return ret
+}
+
+func (b pluginURLBuilder) css() []string {
+	ui := b.Plugin.UI
+	if len(ui.CSS) == 0 && len(ui.ExternalCSS) == 0 {
+		return nil
+	}
+
+	var ret []string
+
+	ret = append(ret, b.Plugin.UI.ExternalCSS...)
+	ret = append(ret, b.BaseURL+"/plugin/"+b.Plugin.ID+"/css")
+	return ret
+}
+
+func (b *pluginURLBuilder) paths() *PluginPaths {
+	return &PluginPaths{
+		Javascript: b.javascript(),
+		CSS:        b.css(),
+	}
+}
+
+func (r *pluginResolver) Paths(ctx context.Context, obj *plugin.Plugin) (*PluginPaths, error) {
+	baseURL, _ := ctx.Value(BaseURLCtxKey).(string)
+
+	b := pluginURLBuilder{
+		BaseURL: baseURL,
+		Plugin:  obj,
+	}
+
+	return b.paths(), nil
+}

internal/api/routes_custom.go

@@ -5,15 +5,14 @@ import (
 	"strings"
 
 	"github.com/go-chi/chi/v5"
-
-	"github.com/stashapp/stash/internal/manager/config"
+	"github.com/stashapp/stash/pkg/utils"
 )
 
 type customRoutes struct {
-	servedFolders config.URLMap
+	servedFolders utils.URLMap
 }
 
-func getCustomRoutes(servedFolders config.URLMap) chi.Router {
+func getCustomRoutes(servedFolders utils.URLMap) chi.Router {
 	return customRoutes{servedFolders: servedFolders}.Routes()
 }
 

internal/api/routes_plugin.go

@@ -0,0 +1,107 @@
+package api
+
+import (
+	"context"
+	"net/http"
+	"path/filepath"
+	"strings"
+
+	"github.com/go-chi/chi/v5"
+
+	"github.com/stashapp/stash/pkg/plugin"
+)
+
+type pluginRoutes struct {
+	pluginCache *plugin.Cache
+}
+
+func getPluginRoutes(pluginCache *plugin.Cache) chi.Router {
+	return pluginRoutes{
+		pluginCache: pluginCache,
+	}.Routes()
+}
+
+func (rs pluginRoutes) Routes() chi.Router {
+	r := chi.NewRouter()
+
+	r.Route("/{pluginId}", func(r chi.Router) {
+		r.Use(rs.PluginCtx)
+		r.Get("/assets/*", rs.Assets)
+		r.Get("/javascript", rs.Javascript)
+		r.Get("/css", rs.CSS)
+	})
+
+	return r
+}
+
+func (rs pluginRoutes) Assets(w http.ResponseWriter, r *http.Request) {
+	p := r.Context().Value(pluginKey).(*plugin.Plugin)
+
+	if !p.Enabled {
+		http.Error(w, "plugin disabled", http.StatusBadRequest)
+		return
+	}
+
+	prefix := "/plugin/" + chi.URLParam(r, "pluginId") + "/assets"
+
+	r.URL.Path = strings.Replace(r.URL.Path, prefix, "", 1)
+
+	// http.FileServer redirects to / if the path ends with index.html
+	r.URL.Path = strings.TrimSuffix(r.URL.Path, "/index.html")
+
+	pluginDir := filepath.Dir(p.ConfigPath)
+
+	// map the path to the applicable filesystem location
+	var dir string
+	r.URL.Path, dir = p.UI.Assets.GetFilesystemLocation(r.URL.Path)
+	if dir == "" {
+		http.NotFound(w, r)
+	}
+
+	dir = filepath.Join(pluginDir, filepath.FromSlash(dir))
+
+	// ensure directory is still within the plugin directory
+	if !strings.HasPrefix(dir, pluginDir) {
+		http.NotFound(w, r)
+		return
+	}
+
+	http.FileServer(http.Dir(dir)).ServeHTTP(w, r)
+}
+
+func (rs pluginRoutes) Javascript(w http.ResponseWriter, r *http.Request) {
+	p := r.Context().Value(pluginKey).(*plugin.Plugin)
+
+	if !p.Enabled {
+		http.Error(w, "plugin disabled", http.StatusBadRequest)
+		return
+	}
+
+	w.Header().Set("Content-Type", "text/javascript")
+	serveFiles(w, r, p.UI.Javascript)
+}
+
+func (rs pluginRoutes) CSS(w http.ResponseWriter, r *http.Request) {
+	p := r.Context().Value(pluginKey).(*plugin.Plugin)
+
+	if !p.Enabled {
+		http.Error(w, "plugin disabled", http.StatusBadRequest)
+		return
+	}
+
+	w.Header().Set("Content-Type", "text/css")
+	serveFiles(w, r, p.UI.CSS)
+}
+
+func (rs pluginRoutes) PluginCtx(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		p := rs.pluginCache.GetPlugin(chi.URLParam(r, "pluginId"))
+		if p == nil {
+			http.Error(w, http.StatusText(404), 404)
+			return
+		}
+
+		ctx := context.WithValue(r.Context(), pluginKey, p)
+		next.ServeHTTP(w, r.WithContext(ctx))
+	})
+}

internal/api/server.go

@@ -138,7 +138,7 @@ func Start() error {
 
 	r.HandleFunc(gqlEndpoint, gqlHandlerFunc)
 	r.HandleFunc(playgroundEndpoint, func(w http.ResponseWriter, r *http.Request) {
-		setPageSecurityHeaders(w, r)
+		setPageSecurityHeaders(w, r, pluginCache.ListPlugins())
 		endpoint := getProxyPrefix(r) + gqlEndpoint
 		gqlPlayground.Handler("GraphQL playground", endpoint)(w, r)
 	})
@@ -150,9 +150,10 @@ func Start() error {
 	r.Mount("/movie", getMovieRoutes(repo))
 	r.Mount("/tag", getTagRoutes(repo))
 	r.Mount("/downloads", getDownloadsRoutes())
+	r.Mount("/plugin", getPluginRoutes(pluginCache))
 
-	r.HandleFunc("/css", cssHandler(c, pluginCache))
-	r.HandleFunc("/javascript", javascriptHandler(c, pluginCache))
+	r.HandleFunc("/css", cssHandler(c))
+	r.HandleFunc("/javascript", javascriptHandler(c))
 	r.HandleFunc("/customlocales", customLocalesHandler(c))
 
 	staticLoginUI := statigz.FileServer(loginUIBox.(fs.ReadDirFS))
@@ -201,7 +202,7 @@ func Start() error {
 			indexHtml = strings.Replace(indexHtml, `<base href="/"`, fmt.Sprintf(`<base href="%s/"`, prefix), 1)
 
 			w.Header().Set("Content-Type", "text/html")
-			setPageSecurityHeaders(w, r)
+			setPageSecurityHeaders(w, r, pluginCache.ListPlugins())
 
 			utils.ServeStaticContent(w, r, []byte(indexHtml))
 		} else {
@@ -289,19 +290,10 @@ func serveFiles(w http.ResponseWriter, r *http.Request, paths []string) {
 	utils.ServeStaticContent(w, r, buffer.Bytes())
 }
 
-func cssHandler(c *config.Instance, pluginCache *plugin.Cache) func(w http.ResponseWriter, r *http.Request) {
+func cssHandler(c *config.Instance) func(w http.ResponseWriter, r *http.Request) {
 	return func(w http.ResponseWriter, r *http.Request) {
-		// add plugin css files first
 		var paths []string
 
-		for _, p := range pluginCache.ListPlugins() {
-			if !p.Enabled {
-				continue
-			}
-
-			paths = append(paths, p.UI.CSS...)
-		}
-
 		if c.GetCSSEnabled() {
 			// search for custom.css in current directory, then $HOME/.stash
 			fn := c.GetCSSPath()
@@ -316,19 +308,10 @@ func cssHandler(c *config.Instance, pluginCache *plugin.Cache) func(w http.Respo
 	}
 }
 
-func javascriptHandler(c *config.Instance, pluginCache *plugin.Cache) func(w http.ResponseWriter, r *http.Request) {
+func javascriptHandler(c *config.Instance) func(w http.ResponseWriter, r *http.Request) {
 	return func(w http.ResponseWriter, r *http.Request) {
-		// add plugin javascript files first
 		var paths []string
 
-		for _, p := range pluginCache.ListPlugins() {
-			if !p.Enabled {
-				continue
-			}
-
-			paths = append(paths, p.UI.Javascript...)
-		}
-
 		if c.GetJavascriptEnabled() {
 			// search for custom.js in current directory, then $HOME/.stash
 			fn := c.GetJavascriptPath()
@@ -408,31 +391,75 @@ func makeTLSConfig(c *config.Instance) (*tls.Config, error) {
 	return tlsConfig, nil
 }
 
-func setPageSecurityHeaders(w http.ResponseWriter, r *http.Request) {
+func isURL(s string) bool {
+	return strings.HasPrefix(s, "http://") || strings.HasPrefix(s, "https://")
+}
+
+func setPageSecurityHeaders(w http.ResponseWriter, r *http.Request, plugins []*plugin.Plugin) {
 	c := config.GetInstance()
 
 	defaultSrc := "data: 'self' 'unsafe-inline'"
-	connectSrc := "data: 'self'"
+	connectSrcSlice := []string{
+		"data:",
+		"'self'",
+	}
 	imageSrc := "data: *"
-	scriptSrc := "'self' http://www.gstatic.com https://www.gstatic.com 'unsafe-inline' 'unsafe-eval'"
-	styleSrc := "'self' 'unsafe-inline'"
+	scriptSrcSlice := []string{
+		"'self'",
+		"http://www.gstatic.com",
+		"https://www.gstatic.com",
+		"'unsafe-inline'",
+		"'unsafe-eval'",
+	}
+	styleSrcSlice := []string{
+		"'self'",
+		"'unsafe-inline'",
+	}
 	mediaSrc := "blob: 'self'"
 
 	// Workaround Safari bug https://bugs.webkit.org/show_bug.cgi?id=201591
 	// Allows websocket requests to any origin
-	connectSrc += " ws: wss:"
+	connectSrcSlice = append(connectSrcSlice, "ws:", "wss:")
 
 	// The graphql playground pulls its frontend from a cdn
 	if r.URL.Path == playgroundEndpoint {
-		connectSrc += " https://cdn.jsdelivr.net"
-		scriptSrc += " https://cdn.jsdelivr.net"
-		styleSrc += " https://cdn.jsdelivr.net"
+		connectSrcSlice = append(connectSrcSlice, "https://cdn.jsdelivr.net")
+		scriptSrcSlice = append(scriptSrcSlice, "https://cdn.jsdelivr.net")
+		styleSrcSlice = append(styleSrcSlice, "https://cdn.jsdelivr.net")
 	}
 
 	if !c.IsNewSystem() && c.GetHandyKey() != "" {
-		connectSrc += " https://www.handyfeeling.com"
+		connectSrcSlice = append(connectSrcSlice, "https://www.handyfeeling.com")
 	}
 
+	for _, plugin := range plugins {
+		if !plugin.Enabled {
+			continue
+		}
+
+		ui := plugin.UI
+
+		for _, url := range ui.ExternalScript {
+			if isURL(url) {
+				scriptSrcSlice = append(scriptSrcSlice, url)
+			}
+		}
+
+		for _, url := range ui.ExternalCSS {
+			if isURL(url) {
+				styleSrcSlice = append(styleSrcSlice, url)
+			}
+		}
+
+		connectSrcSlice = append(connectSrcSlice, ui.CSP.ConnectSrc...)
+		scriptSrcSlice = append(scriptSrcSlice, ui.CSP.ScriptSrc...)
+		styleSrcSlice = append(styleSrcSlice, ui.CSP.StyleSrc...)
+	}
+
+	connectSrc := strings.Join(connectSrcSlice, " ")
+	scriptSrc := strings.Join(scriptSrcSlice, " ")
+	styleSrc := strings.Join(styleSrcSlice, " ")
+
 	cspDirectives := fmt.Sprintf("default-src %s; connect-src %s; img-src %s; script-src %s; style-src %s; media-src %s;", defaultSrc, connectSrc, imageSrc, scriptSrc, styleSrc, mediaSrc)
 	cspDirectives += " worker-src blob:; child-src 'none'; object-src 'none'; form-action 'self';"
 

internal/api/session.go

@@ -50,7 +50,9 @@ func serveLoginPage(loginUIBox fs.FS, w http.ResponseWriter, r *http.Request, re
 	}
 
 	w.Header().Set("Content-Type", "text/html")
-	setPageSecurityHeaders(w, r)
+
+	// we shouldn't need to set plugin exceptions here
+	setPageSecurityHeaders(w, r, nil)
 
 	utils.ServeStaticContent(w, r, buffer.Bytes())
 }

internal/manager/config/config.go

@@ -21,6 +21,7 @@ import (
 	"github.com/stashapp/stash/pkg/logger"
 	"github.com/stashapp/stash/pkg/models"
 	"github.com/stashapp/stash/pkg/models/paths"
+	"github.com/stashapp/stash/pkg/utils"
 )
 
 const (
@@ -1019,7 +1020,7 @@ func (i *Instance) GetMaxSessionAge() int {
 
 // GetCustomServedFolders gets the map of custom paths to their applicable
 // filesystem locations
-func (i *Instance) GetCustomServedFolders() URLMap {
+func (i *Instance) GetCustomServedFolders() utils.URLMap {
 	return i.getStringMapString(CustomServedFolders)
 }
 

internal/manager/config/urlmap.go

@@ -1,21 +0,0 @@
-package config
-
-import "strings"
-
-type URLMap map[string]string
-
-// GetFilesystemLocation returns the adjusted URL and the filesystem location
-func (m URLMap) GetFilesystemLocation(url string) (string, string) {
-	root := m["/"]
-	for k, v := range m {
-		if k != "/" && strings.HasPrefix(url, k) {
-			return strings.TrimPrefix(url, k), v
-		}
-	}
-
-	if root != "" {
-		return url, root
-	}
-
-	return url, ""
-}

internal/manager/config/urlmap_test.go

@@ -1,28 +0,0 @@
-package config
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-)
-
-func TestURLMapGetFilesystemLocation(t *testing.T) {
-	// create the URLMap
-	urlMap := make(URLMap)
-	urlMap["/"] = "root"
-	urlMap["/foo"] = "bar"
-
-	url, fs := urlMap.GetFilesystemLocation("/foo/bar")
-	assert.Equal(t, "/bar", url)
-	assert.Equal(t, urlMap["/foo"], fs)
-
-	url, fs = urlMap.GetFilesystemLocation("/bar")
-	assert.Equal(t, "/bar", url)
-	assert.Equal(t, urlMap["/"], fs)
-
-	delete(urlMap, "/")
-
-	url, fs = urlMap.GetFilesystemLocation("/bar")
-	assert.Equal(t, "/bar", url)
-	assert.Equal(t, "", fs)
-}

pkg/plugin/config.go

@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/stashapp/stash/pkg/utils"
 	"gopkg.in/yaml.v2"
 )
 
@@ -64,27 +65,81 @@ type Config struct {
 	Settings map[string]SettingConfig `yaml:"settings"`
 }
 
+type PluginCSP struct {
+	ScriptSrc  []string `json:"script-src" yaml:"script-src"`
+	StyleSrc   []string `json:"style-src" yaml:"style-src"`
+	ConnectSrc []string `json:"connect-src" yaml:"connect-src"`
+}
+
 type UIConfig struct {
+	// Content Security Policy configuration for the plugin.
+	CSP PluginCSP `yaml:"csp"`
+
 	// Javascript files that will be injected into the stash UI.
+	// These may be URLs or paths to files relative to the plugin configuration file.
 	Javascript []string `yaml:"javascript"`
 
 	// CSS files that will be injected into the stash UI.
+	// These may be URLs or paths to files relative to the plugin configuration file.
 	CSS []string `yaml:"css"`
+
+	// Assets is a map of URL prefixes to hosted directories.
+	// This allows plugins to serve static assets from a URL path.
+	// Plugin assets are exposed via the /plugin/{pluginId}/assets path.
+	// For example, if the plugin configuration file contains:
+	// /foo: bar
+	// /bar: baz
+	// /: root
+	// Then the following requests will be mapped to the following files:
+	// /plugin/{pluginId}/assets/foo/file.txt -> {pluginDir}/foo/file.txt
+	// /plugin/{pluginId}/assets/bar/file.txt -> {pluginDir}/baz/file.txt
+	// /plugin/{pluginId}/assets/file.txt -> {pluginDir}/root/file.txt
+	Assets utils.URLMap `yaml:"assets"`
+}
+
+func isURL(s string) bool {
+	return strings.HasPrefix(s, "http://") || strings.HasPrefix(s, "https://")
 }
 
 func (c UIConfig) getCSSFiles(parent Config) []string {
-	ret := make([]string, len(c.CSS))
-	for i, v := range c.CSS {
-		ret[i] = filepath.Join(parent.getConfigPath(), v)
+	var ret []string
+	for _, v := range c.CSS {
+		if !isURL(v) {
+			ret = append(ret, filepath.Join(parent.getConfigPath(), v))
+		}
+	}
+
+	return ret
+}
+
+func (c UIConfig) getExternalCSS() []string {
+	var ret []string
+	for _, v := range c.CSS {
+		if isURL(v) {
+			ret = append(ret, v)
+		}
 	}
 
 	return ret
 }
 
 func (c UIConfig) getJavascriptFiles(parent Config) []string {
-	ret := make([]string, len(c.Javascript))
-	for i, v := range c.Javascript {
-		ret[i] = filepath.Join(parent.getConfigPath(), v)
+	var ret []string
+	for _, v := range c.Javascript {
+		if !isURL(v) {
+			ret = append(ret, filepath.Join(parent.getConfigPath(), v))
+		}
+	}
+
+	return ret
+}
+
+func (c UIConfig) getExternalScripts() []string {
+	var ret []string
+	for _, v := range c.Javascript {
+		if isURL(v) {
+			ret = append(ret, v)
+		}
 	}
 
 	return ret
@@ -184,10 +239,14 @@ func (c Config) toPlugin() *Plugin {
 		Tasks:       c.getPluginTasks(false),
 		Hooks:       c.getPluginHooks(false),
 		UI: PluginUI{
+			ExternalScript: c.UI.getExternalScripts(),
+			ExternalCSS:    c.UI.getExternalCSS(),
 			Javascript:     c.UI.getJavascriptFiles(c),
 			CSS:            c.UI.getCSSFiles(c),
+			Assets:         c.UI.Assets,
 		},
 		Settings:   c.getPluginSettings(),
+		ConfigPath: c.path,
 	}
 }
 

pkg/plugin/plugins.go

@@ -21,6 +21,7 @@ import (
 	"github.com/stashapp/stash/pkg/session"
 	"github.com/stashapp/stash/pkg/sliceutil"
 	"github.com/stashapp/stash/pkg/txn"
+	"github.com/stashapp/stash/pkg/utils"
 )
 
 type Plugin struct {
@@ -35,14 +36,39 @@ type Plugin struct {
 	Settings    []PluginSetting `json:"settings"`
 
 	Enabled bool `json:"enabled"`
+
+	// ConfigPath is the path to the plugin's configuration file.
+	ConfigPath string `json:"-"`
 }
 
 type PluginUI struct {
+	// Content Security Policy configuration for the plugin.
+	CSP PluginCSP `json:"csp"`
+
+	// External Javascript files that will be injected into the stash UI.
+	ExternalScript []string `json:"external_script"`
+
+	// External CSS files that will be injected into the stash UI.
+	ExternalCSS []string `json:"external_css"`
+
 	// Javascript files that will be injected into the stash UI.
 	Javascript []string `json:"javascript"`
 
 	// CSS files that will be injected into the stash UI.
 	CSS []string `json:"css"`
+
+	// Assets is a map of URL prefixes to hosted directories.
+	// This allows plugins to serve static assets from a URL path.
+	// Plugin assets are exposed via the /plugin/{pluginId}/assets path.
+	// For example, if the plugin configuration file contains:
+	// /foo: bar
+	// /bar: baz
+	// /: root
+	// Then the following requests will be mapped to the following files:
+	// /plugin/{pluginId}/assets/foo/file.txt -> {pluginDir}/foo/file.txt
+	// /plugin/{pluginId}/assets/bar/file.txt -> {pluginDir}/baz/file.txt
+	// /plugin/{pluginId}/assets/file.txt -> {pluginDir}/root/file.txt
+	Assets utils.URLMap `json:"assets"`
 }
 
 type PluginSetting struct {
@@ -173,6 +199,22 @@ func (c Cache) ListPlugins() []*Plugin {
 	return ret
 }
 
+// GetPlugin returns the plugin with the given ID.
+// Returns nil if the plugin is not found.
+func (c Cache) GetPlugin(id string) *Plugin {
+	disabledPlugins := c.config.GetDisabledPlugins()
+	plugin := c.getPlugin(id)
+	if plugin != nil {
+		p := plugin.toPlugin()
+
+		disabled := sliceutil.Contains(disabledPlugins, p.ID)
+		p.Enabled = !disabled
+		return p
+	}
+
+	return nil
+}
+
 // ListPluginTasks returns all runnable plugin tasks in all loaded plugins.
 func (c Cache) ListPluginTasks() []*PluginTask {
 	var ret []*PluginTask

pkg/utils/urlmap.go

@@ -0,0 +1,30 @@
+package utils
+
+import "strings"
+
+// URLMap is a map of URL prefixes to filesystem locations
+type URLMap map[string]string
+
+// GetFilesystemLocation returns the adjusted URL and the filesystem location
+func (m URLMap) GetFilesystemLocation(url string) (newURL string, fsPath string) {
+	newURL = url
+	if m == nil {
+		return
+	}
+
+	root := m["/"]
+	for k, v := range m {
+		if k != "/" && strings.HasPrefix(url, k) {
+			newURL = strings.TrimPrefix(url, k)
+			fsPath = v
+			return
+		}
+	}
+
+	if root != "" {
+		fsPath = root
+		return
+	}
+
+	return
+}

pkg/utils/urlmap_test.go

@@ -0,0 +1,70 @@
+package utils
+
+import (
+	"testing"
+)
+
+func TestURLMap_GetFilesystemLocation(t *testing.T) {
+	// create the URLMap
+	urlMap := make(URLMap)
+	urlMap["/"] = "root"
+	urlMap["/foo"] = "bar"
+
+	empty := make(URLMap)
+	var nilMap URLMap
+
+	tests := []struct {
+		name       string
+		urlMap     URLMap
+		url        string
+		wantNewURL string
+		wantFsPath string
+	}{
+		{
+			name:       "simple",
+			urlMap:     urlMap,
+			url:        "/foo/bar",
+			wantNewURL: "/bar",
+			wantFsPath: "bar",
+		},
+		{
+			name:       "root",
+			urlMap:     urlMap,
+			url:        "/baz",
+			wantNewURL: "/baz",
+			wantFsPath: "root",
+		},
+		{
+			name:       "root",
+			urlMap:     urlMap,
+			url:        "/baz",
+			wantNewURL: "/baz",
+			wantFsPath: "root",
+		},
+		{
+			name:       "empty",
+			urlMap:     empty,
+			url:        "/xyz",
+			wantNewURL: "/xyz",
+			wantFsPath: "",
+		},
+		{
+			name:       "nil",
+			urlMap:     nilMap,
+			url:        "/xyz",
+			wantNewURL: "/xyz",
+			wantFsPath: "",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			gotNewURL, gotFsPath := tt.urlMap.GetFilesystemLocation(tt.url)
+			if gotNewURL != tt.wantNewURL {
+				t.Errorf("URLMap.GetFilesystemLocation() gotNewURL = %v, want %v", gotNewURL, tt.wantNewURL)
+			}
+			if gotFsPath != tt.wantFsPath {
+				t.Errorf("URLMap.GetFilesystemLocation() gotFsPath = %v, want %v", gotFsPath, tt.wantFsPath)
+			}
+		})
+	}
+}

ui/v2.5/src/App.tsx

@@ -18,6 +18,7 @@ import locales, { registerCountry } from "src/locales";
 import {
   useConfiguration,
   useConfigureUI,
+  usePlugins,
   useSystemStatus,
 } from "src/core/StashService";
 import flattenMessages from "./utils/flattenMessages";
@@ -40,6 +41,9 @@ import { releaseNotes } from "./docs/en/ReleaseNotes";
 import { getPlatformURL } from "./core/createClient";
 import { lazyComponent } from "./utils/lazyComponent";
 import { isPlatformUniquelyRenderedByApple } from "./utils/apple";
+import useScript, { useCSS } from "./hooks/useScript";
+import { useMemoOnce } from "./hooks/state";
+import { uniq } from "lodash-es";
 
 const Performers = lazyComponent(
   () => import("./components/Performers/Performers")
@@ -149,6 +153,39 @@ export const App: React.FC = () => {
     setLocale();
   }, [customMessages, language]);
 
+  const {
+    data: plugins,
+    loading: pluginsLoading,
+    error: pluginsError,
+  } = usePlugins();
+
+  const pluginJavascripts = useMemoOnce(() => {
+    return [
+      uniq(
+        plugins?.plugins
+          ?.filter((plugin) => plugin.enabled && plugin.paths.javascript)
+          .map((plugin) => plugin.paths.javascript!)
+          .flat() ?? []
+      ),
+      !pluginsLoading && !pluginsError,
+    ];
+  }, [plugins?.plugins, pluginsLoading, pluginsError]);
+
+  const pluginCSS = useMemoOnce(() => {
+    return [
+      uniq(
+        plugins?.plugins
+          ?.filter((plugin) => plugin.enabled && plugin.paths.css)
+          .map((plugin) => plugin.paths.css!)
+          .flat() ?? []
+      ),
+      !pluginsLoading && !pluginsError,
+    ];
+  }, [plugins, pluginsLoading, pluginsError]);
+
+  useScript(pluginJavascripts ?? [], !pluginsLoading && !pluginsError);
+  useCSS(pluginCSS ?? [], !pluginsLoading && !pluginsError);
+
   const location = useLocation();
   const history = useHistory();
   const setupMatch = useRouteMatch(["/setup", "/migrate"]);

ui/v2.5/src/docs/en/Manual/Plugins.md

@@ -43,6 +43,22 @@ ui:
   javascript:
     - <path to javascript file>
 
+  # optional list of assets 
+  assets:
+    urlPrefix: fsLocation
+    ...
+
+  # content-security policy overrides
+  csp:
+    script-src:
+      - http://alloweddomain.com
+    
+    style-src:
+      - http://alloweddomain.com
+    
+    connect-src:
+      - http://alloweddomain.com
+
 # the following are used for plugin tasks only
 exec:
   - ...
@@ -56,6 +72,31 @@ The `name`, `description`, `version` and `url` fields are displayed on the plugi
 
 The `exec`, `interface`, `errLog` and `tasks` fields are used only for plugins with tasks.
 
+## UI Configuration
+
+The `css` and `javascript` field values may be relative paths to the plugin configuration file, or
+may be full external URLs.
+
+The `assets` field is a map of URL prefixes to filesystem paths relative to the plugin configuration file.
+Assets are mounted to the `/plugin/{pluginID}/assets` path. 
+
+As an example, for a plugin with id `foo` with the following `assets` value:
+```
+assets:
+  foo: bar
+  root: .
+```
+The following URLs will be mapped to these locations:
+`/plugin/foo/assets/foo/file.txt` -> `{pluginDir}/bar/file.txt`
+`/plugin/foo/assets/file.txt` -> `{pluginDir}/file.txt`
+`/plugin/foo/assets/bar/file.txt` -> `{pluginDir}/bar/file.txt` (via the `root` entry)
+
+Mappings that try to go outside of the directory containing the plugin configuration file will be
+ignored.
+
+The `csp` field contains overrides to the content security policies. The URLs in `script-src`,
+`style-src` and `connect-src` will be added to the applicable content security policy.
+
 See [External Plugins](/help/ExternalPlugins.md) for details for making plugins with external tasks.
 
 See [Embedded Plugins](/help/EmbeddedPlugins.md) for details for making plugins with embedded tasks.

ui/v2.5/src/hooks/state.ts

@@ -33,6 +33,30 @@ export function useInitialState<T>(
   return [value, setValue, setInitialValue];
 }
 
+// useMemoOnce is a hook that returns a value once the ready flag is set to true.
+// The value is only set once, and will not be updated once it has been set.
+/* eslint-disable react-hooks/exhaustive-deps */
+export function useMemoOnce<T>(
+  fn: () => [T, boolean],
+  deps: React.DependencyList
+) {
+  const [storedValue, setStoredValue] = React.useState<T>();
+  const isFirst = React.useRef(true);
+
+  React.useEffect(() => {
+    if (isFirst.current) {
+      const [v, ready] = fn();
+      if (ready) {
+        setStoredValue(v);
+        isFirst.current = false;
+      }
+    }
+  }, deps);
+
+  return storedValue;
+}
+/* eslint-enable react-hooks/exhaustive-deps */
+
 // useCompare is a hook that returns true if the value has changed since the last render.
 export function useCompare<T>(val: T) {
   const prevVal = usePrevious(val);

ui/v2.5/src/hooks/useScript.tsx

@@ -1,22 +1,72 @@
-import { useEffect } from "react";
+import { useEffect, useMemo } from "react";
+
+const useScript = (urls: string | string[], condition?: boolean) => {
+  const urlArray = useMemo(() => {
+    if (!Array.isArray(urls)) {
+      return [urls];
+    }
+
+    return urls;
+  }, [urls]);
 
-const useScript = (url: string, condition?: boolean) => {
   useEffect(() => {
+    const scripts = urlArray.map((url) => {
       const script = document.createElement("script");
 
       script.src = url;
       script.async = true;
+      return script;
+    });
 
     if (condition) {
+      scripts.forEach((script) => {
         document.head.appendChild(script);
+      });
     }
 
     return () => {
       if (condition) {
+        scripts.forEach((script) => {
           document.head.removeChild(script);
+        });
       }
     };
-  }, [url, condition]);
+  }, [urlArray, condition]);
+};
+
+export const useCSS = (urls: string | string[], condition?: boolean) => {
+  const urlArray = useMemo(() => {
+    if (!Array.isArray(urls)) {
+      return [urls];
+    }
+
+    return urls;
+  }, [urls]);
+
+  useEffect(() => {
+    const links = urlArray.map((url) => {
+      const link = document.createElement("link");
+
+      link.href = url;
+      link.rel = "stylesheet";
+      link.type = "text/css";
+      return link;
+    });
+
+    if (condition) {
+      links.forEach((link) => {
+        document.head.appendChild(link);
+      });
+    }
+
+    return () => {
+      if (condition) {
+        links.forEach((link) => {
+          document.head.removeChild(link);
+        });
+      }
+    };
+  }, [urlArray, condition]);
 };
 
 export default useScript;