package middleware import ( "net" "net/http" "strconv" "strings" "time" ) // Replacer is a type which can replace placeholder // substrings in a string with actual values from a // http.Request and responseRecorder. Always use // NewReplacer to get one of these. type Replacer interface { Replace(string) string } type replacer struct { replacements map[string]string emptyValue string } // NewReplacer makes a new replacer based on r and rr. // Do not create a new replacer until r and rr have all // the needed values, because this function copies those // values into the replacer. func NewReplacer(r *http.Request, rr *responseRecorder, emptyValue string) Replacer { rep := replacer{ replacements: map[string]string{ "{method}": r.Method, "{scheme}": func() string { if r.TLS != nil { return "https" } return "http" }(), "{host}": r.Host, "{path}": r.URL.Path, "{query}": r.URL.RawQuery, "{fragment}": r.URL.Fragment, "{proto}": r.Proto, "{remote}": func() string { if fwdFor := r.Header.Get("X-Forwarded-For"); fwdFor != "" { return fwdFor } host, _, err := net.SplitHostPort(r.RemoteAddr) if err != nil { return r.RemoteAddr } return host }(), "{port}": func() string { _, port, err := net.SplitHostPort(r.RemoteAddr) if err != nil { return "" } return port }(), "{uri}": r.URL.RequestURI(), "{when}": func() string { return time.Now().Format(timeFormat) }(), }, emptyValue: emptyValue, } if rr != nil { rep.replacements["{status}"] = strconv.Itoa(rr.status) rep.replacements["{size}"] = strconv.Itoa(rr.size) rep.replacements["{latency}"] = time.Since(rr.start).String() } // Header placeholders for header, val := range r.Header { rep.replacements[headerReplacer+header+"}"] = strings.Join(val, ",") } return rep } // Replace performs a replacement of values on s and returns // the string with the replaced values. func (r replacer) Replace(s string) string { for placeholder, replacement := range r.replacements { if replacement == "" { replacement = r.emptyValue } s = strings.Replace(s, placeholder, replacement, -1) } // Replace any header placeholders that weren't found for strings.Contains(s, headerReplacer) { idxStart := strings.Index(s, headerReplacer) endOffset := idxStart + len(headerReplacer) idxEnd := strings.Index(s[endOffset:], "}") if idxEnd > -1 { s = s[:idxStart] + r.emptyValue + s[endOffset+idxEnd+1:] } else { break } } return s } const ( timeFormat = "02/Jan/2006:15:04:05 -0700" headerReplacer = "{>" )