149 lines
3.5 KiB
Go
149 lines
3.5 KiB
Go
// (c) 2018 Karthik Karanth (https://github.com/medakk/gotiny)
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// (c) 2018-2021 Andreas Neue <an@dnix.de>
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package main
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import (
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"flag"
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"fmt"
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"io"
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"log"
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"net/http"
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"strconv"
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"strings"
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"github.com/davidbyttow/govips/v2/vips"
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)
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var (
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imgServer = flag.String("s", "https://images.example.com/", "URL prefix")
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listenAddr = flag.String("l", "0.0.0.0:8080", "Listen address")
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sizesFilter = flag.String("f", "", "Allowed sizes")
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)
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func init() {
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flag.Parse()
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}
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func transform(w http.ResponseWriter, r *http.Request) {
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// Get the query parameters from the request URL
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path := r.URL.EscapedPath()
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parm := strings.Split(path, "/")
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if len(parm) < 4 {
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writeError(w, "", "", "error in arguments", http.StatusBadRequest)
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return
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}
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method := parm[1]
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args := parm[2]
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imgPath := strings.Join(parm[3:], "/")
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// Start fetching the image from the given url
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resp, err := http.Get(*imgServer + imgPath)
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if err != nil {
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writeError(w, imgPath, method, "failed to fetch image", http.StatusNotFound)
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return
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}
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defer resp.Body.Close()
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// Ensure that a valid response was given
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if resp.StatusCode/100 != 2 {
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writeError(w, imgPath, method, fmt.Sprintf("failed to fetch image (%v)", resp.StatusCode), http.StatusBadRequest)
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return
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}
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buf := []byte{}
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errMsg := ""
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errCode := 200
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switch method {
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case "pass":
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break
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case "resize":
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buf, errMsg, errCode = doResize(resp.Body, args)
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if buf == nil {
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writeError(w, imgPath, method, errMsg, errCode)
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}
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case "thumbnail":
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break
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default:
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writeError(w, imgPath, method, "unknown method", http.StatusBadRequest)
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return
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}
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_, err = w.Write(buf)
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if err != nil {
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writeError(w, imgPath, method, fmt.Sprintf("%v", err), http.StatusInternalServerError)
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return
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}
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}
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func doResize(body io.ReadCloser, args string) ([]byte, string, int) {
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allowed := strings.Split(*sizesFilter, ",")
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forbidden := true
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if allowed[0] == "*" {
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forbidden = false
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} else {
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for _, v := range allowed {
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if args == v {
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forbidden = false
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break
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}
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}
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}
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if forbidden {
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return nil, "size is not allowed", http.StatusForbidden
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}
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size := strings.Split(args, "x")
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if len(size) < 2 {
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return nil, "width and height are required", http.StatusBadRequest
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}
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width := size[0]
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height := size[1]
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// Validate that all three required fields are present
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if width == "" || height == "" {
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return nil, "width and height are required", http.StatusBadRequest
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}
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// Convert width and height to integers
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iw, errW := strconv.Atoi(width)
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ih, errH := strconv.Atoi(height)
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if errW != nil || errH != nil {
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return nil, "width and height must be integers", http.StatusBadRequest
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}
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// Read from response body, convert and write to output buffer
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img, err := vips.NewImageFromReader(body)
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if err != nil {
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return nil, fmt.Sprintf("%v", err), http.StatusInternalServerError
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}
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err = img.Thumbnail(iw, ih, 0)
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if err != nil {
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return nil, fmt.Sprintf("%v", err), http.StatusInternalServerError
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}
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ep := vips.NewDefaultExportParams() // default export params are sufficient
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buf, _, _ := img.Export(ep)
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if err != nil {
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return nil, fmt.Sprintf("%v", err), http.StatusInternalServerError
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}
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return buf, "", 0
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}
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func writeError(w http.ResponseWriter, imgPath, method, err string, status int) {
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w.WriteHeader(status)
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w.Write([]byte(fmt.Sprintf("Error [%s %s]: %s", method, imgPath, err)))
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}
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func main() {
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// Start vips with the default configuration
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vips.Startup(nil)
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defer vips.Shutdown()
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http.HandleFunc("/", transform)
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log.Fatal(http.ListenAndServe(*listenAddr, nil))
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}
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