99 lines
2.1 KiB
Go
99 lines
2.1 KiB
Go
package staticimages
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import (
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"io"
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"io/fs"
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"net/http"
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"os"
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"path"
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"strings"
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"time"
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"github.com/go-chi/chi/v5"
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)
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const cacheControl = "public, max-age=31536000, immutable"
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const svgContentSecurityPolicy = "default-src 'none'; style-src 'unsafe-inline'; sandbox"
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const fallbackContentType = "application/octet-stream"
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var contentTypeExtensions = map[string]string{
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".png": "image/png",
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".jpeg": "image/jpeg",
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".webp": "image/webp",
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".svg": "image/svg+xml",
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}
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type Handler struct {
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uploadDir fs.FS
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modTime time.Time
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}
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func NewHandler(uploadDir string) *Handler {
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return &Handler{
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uploadDir: os.DirFS(uploadDir),
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modTime: time.Now(),
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}
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}
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func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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w.Header().Set("X-Content-Type-Options", "nosniff")
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cleaned := cleanPath(requestedPath(r))
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file, stat, ok := h.openFile(cleaned)
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if !ok {
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http.NotFound(w, r)
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return
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}
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defer file.Close()
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content, ok := file.(io.ReadSeeker)
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if !ok {
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http.Error(w, "File not seekable", http.StatusInternalServerError)
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return
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}
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contentType := contentTypeFor(cleaned)
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w.Header().Set("Content-Type", contentType)
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w.Header().Set("Cache-Control", cacheControl)
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if contentType == "image/svg+xml" {
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w.Header().Set("Content-Security-Policy", svgContentSecurityPolicy)
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}
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http.ServeContent(w, r, cleaned, stat.ModTime(), content)
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}
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func requestedPath(r *http.Request) string {
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if rctx := chi.RouteContext(r.Context()); rctx != nil && rctx.RoutePath != "" {
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return rctx.RoutePath
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}
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return r.URL.Path
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}
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func cleanPath(p string) string {
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return strings.TrimPrefix(path.Clean("/"+p), "/")
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}
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func (h *Handler) openFile(p string) (fs.File, fs.FileInfo, bool) {
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if p == "" || p == "." {
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return nil, nil, false
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}
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file, err := h.uploadDir.Open(p)
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if err != nil {
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return nil, nil, false
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}
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stat, err := file.Stat()
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if err != nil || stat.IsDir() {
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file.Close()
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return nil, nil, false
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}
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return file, stat, true
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}
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func contentTypeFor(p string) string {
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ext := path.Ext(p)
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if contentType, ok := contentTypeExtensions[ext]; ok {
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return contentType
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}
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return fallbackContentType
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}
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