Method serveImage

imageproxy.go:227–346

serveImage handles incoming requests for proxied images.

(w http.ResponseWriter, r *http.Request)

// serveImage handles incoming requests for proxied images.
func (p *Proxy) serveImage(w http.ResponseWriter, r *http.Request) {
	req, err := NewRequest(r, p.DefaultBaseURL)
	if err != nil {
		msg := fmt.Sprintf("invalid request URL: %v", err)
		p.log(msg)
		http.Error(w, msg, http.StatusBadRequest)
		return
	}

	if err := p.allowed(req); err != nil {
		p.logf("%s: %v", err, req)
		http.Error(w, msgNotAllowed, http.StatusForbidden)
		return
	}

	// assign static settings from proxy to req.Options
	req.Options.ScaleUp = p.ScaleUp

	actualReq, _ := http.NewRequest("GET", req.String(), nil)
	if p.UserAgent != "" {
		actualReq.Header.Set("User-Agent", p.UserAgent)
	}
	if len(p.ContentTypes) != 0 {
		actualReq.Header.Set("Accept", strings.Join(p.ContentTypes, ", "))
	}
	if p.IncludeReferer {
		// pass along the referer header from the original request
		copyHeader(actualReq.Header, r.Header, "referer")
	}
	if len(p.PassRequestHeaders) != 0 {
		copyHeader(actualReq.Header, r.Header, p.PassRequestHeaders...)
	}
	if p.FollowRedirects {
		// FollowRedirects is true (default), ensure that the redirected host is allowed
		p.Client.CheckRedirect = func(newreq *http.Request, via []*http.Request) error {
			if len(via) > maxRedirects {
				if p.Verbose {
					p.logf("followed too many redirects (%d).", len(via))
				}
				return errTooManyRedirects
			}
			if hostMatches(p.DenyHosts, newreq.URL) {
				http.Error(w, msgNotAllowedInRedirect, http.StatusForbidden)
				return errNotAllowed
			}
			return nil
		}
	} else {
		// FollowRedirects is false, don't follow redirects
		p.Client.CheckRedirect = func(newreq *http.Request, via []*http.Request) error {
			return http.ErrUseLastResponse
		}
	}
	resp, err := p.Client.Do(actualReq)

	if err != nil {
		msg := fmt.Sprintf("error fetching remote image: %v", err)
		p.log(msg)