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116 lines
2.9 KiB
Go
116 lines
2.9 KiB
Go
// Package errors implements an HTTP error handling middleware.
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package errors
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import (
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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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"os"
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"runtime"
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"strings"
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"time"
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"github.com/mholt/caddy/middleware"
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)
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// ErrorHandler handles HTTP errors (or errors from other middleware).
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type ErrorHandler struct {
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Next middleware.Handler
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ErrorPages map[int]string // map of status code to filename
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LogFile string
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Log *log.Logger
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}
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func (h ErrorHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
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defer h.recovery(w, r)
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status, err := h.Next.ServeHTTP(w, r)
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if err != nil {
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h.Log.Printf("%s [ERROR %d %s] %v", time.Now().Format(timeFormat), status, r.URL.Path, err)
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}
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if status >= 400 {
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h.errorPage(w, status)
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return 0, err // status < 400 signals that a response has been written
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}
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return status, err
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}
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// errorPage serves a static error page to w according to the status
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// code. If there is an error serving the error page, a plaintext error
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// message is written instead, and the extra error is logged.
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func (h ErrorHandler) errorPage(w http.ResponseWriter, code int) {
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defaultBody := fmt.Sprintf("%d %s", code, http.StatusText(code))
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// See if an error page for this status code was specified
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if pagePath, ok := h.ErrorPages[code]; ok {
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// Try to open it
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errorPage, err := os.Open(pagePath)
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if err != nil {
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// An error handling an error... <insert grumpy cat here>
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h.Log.Printf("HTTP %d could not load error page %s: %v", code, pagePath, err)
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http.Error(w, defaultBody, code)
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return
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}
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defer errorPage.Close()
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// Copy the page body into the response
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w.Header().Set("Content-Type", "text/html; charset=utf-8")
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w.WriteHeader(code)
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_, err = io.Copy(w, errorPage)
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if err != nil {
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// Epic fail... sigh.
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h.Log.Printf("HTTP %d could not respond with %s: %v", code, pagePath, err)
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http.Error(w, defaultBody, code)
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}
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return
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}
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// Default error response
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http.Error(w, defaultBody, code)
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}
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func (h ErrorHandler) recovery(w http.ResponseWriter, r *http.Request) {
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rec := recover()
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if rec == nil {
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return
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}
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// Obtain source of panic
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// From: https://gist.github.com/swdunlop/9629168
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var name, file string // function name, file name
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var line int
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var pc [16]uintptr
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n := runtime.Callers(3, pc[:])
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for _, pc := range pc[:n] {
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fn := runtime.FuncForPC(pc)
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if fn == nil {
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continue
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}
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file, line = fn.FileLine(pc)
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name = fn.Name()
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if !strings.HasPrefix(name, "runtime.") {
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break
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}
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}
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// Trim file path
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delim := "/caddy/"
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pkgPathPos := strings.Index(file, delim)
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if pkgPathPos > -1 && len(file) > pkgPathPos+len(delim) {
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file = file[pkgPathPos+len(delim):]
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}
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// Currently we don't use the function name, as file:line is more conventional
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h.Log.Printf("%s [PANIC %s] %s:%d - %v", time.Now().Format(timeFormat), r.URL.String(), file, line, rec)
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h.errorPage(w, http.StatusInternalServerError)
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}
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const DefaultLogFilename = "error.log"
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const timeFormat = "02/Jan/2006:15:04:05 -0700"
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