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77 lines
2.5 KiB
Go
77 lines
2.5 KiB
Go
package middleware
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import (
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"bytes"
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"io"
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"net/http"
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"path/filepath"
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"strconv"
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"strings"
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"github.com/yusing/go-proxy/internal/logging"
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gphttp "github.com/yusing/go-proxy/internal/net/http"
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"github.com/yusing/go-proxy/internal/net/http/middleware/errorpage"
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)
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type customErrorPage struct{}
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var CustomErrorPage = NewMiddleware[customErrorPage]()
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// before implements RequestModifier.
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func (customErrorPage) before(w http.ResponseWriter, r *http.Request) (proceed bool) {
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return !ServeStaticErrorPageFile(w, r)
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}
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// modifyResponse implements ResponseModifier.
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func (customErrorPage) modifyResponse(resp *http.Response) error {
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// only handles non-success status code and html/plain content type
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contentType := gphttp.GetContentType(resp.Header)
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if !gphttp.IsSuccess(resp.StatusCode) && (contentType.IsHTML() || contentType.IsPlainText()) {
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errorPage, ok := errorpage.GetErrorPageByStatus(resp.StatusCode)
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if ok {
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logging.Debug().Msgf("error page for status %d loaded", resp.StatusCode)
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_, _ = io.Copy(io.Discard, resp.Body) // drain the original body
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resp.Body.Close()
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resp.Body = io.NopCloser(bytes.NewReader(errorPage))
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resp.ContentLength = int64(len(errorPage))
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resp.Header.Set(gphttp.HeaderContentLength, strconv.Itoa(len(errorPage)))
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resp.Header.Set(gphttp.HeaderContentType, "text/html; charset=utf-8")
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} else {
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logging.Error().Msgf("unable to load error page for status %d", resp.StatusCode)
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}
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return nil
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}
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return nil
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}
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func ServeStaticErrorPageFile(w http.ResponseWriter, r *http.Request) (served bool) {
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path := r.URL.Path
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if path != "" && path[0] != '/' {
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path = "/" + path
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}
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if strings.HasPrefix(path, gphttp.StaticFilePathPrefix) {
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filename := path[len(gphttp.StaticFilePathPrefix):]
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file, ok := errorpage.GetStaticFile(filename)
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if !ok {
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logging.Error().Msg("unable to load resource " + filename)
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return false
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}
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ext := filepath.Ext(filename)
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switch ext {
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case ".html":
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w.Header().Set(gphttp.HeaderContentType, "text/html; charset=utf-8")
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case ".js":
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w.Header().Set(gphttp.HeaderContentType, "application/javascript; charset=utf-8")
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case ".css":
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w.Header().Set(gphttp.HeaderContentType, "text/css; charset=utf-8")
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default:
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logging.Error().Msgf("unexpected file type %q for %s", ext, filename)
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}
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if _, err := w.Write(file); err != nil {
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logging.Err(err).Msg("unable to write resource " + filename)
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http.Error(w, "Error page failure", http.StatusInternalServerError)
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}
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return true
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}
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return false
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}
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