shizaru/httphandlers.go

package main

import (
//	"fmt"
	"golang.org/x/net/html"
	"mime"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"
)

func LoggingWrapper(log *os.File, handler http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
			handler(w, r)
			t := time.Now()
			log.WriteString(r.RemoteAddr + " " + t.Format(time.UnixDate) + " " + r.RequestURI + "\n")
	}
}

func GetHandler(config Config) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		// Security first!
		w.Header().Set("Strict-Transport-Security", "max-age=31536000")
		// Default to text/plain, as used for errors
		w.Header().Set("Content-Type", "text/plain")
		// Fail if request method is not GET or HEAD
		if r.Method != "GET" && r.Method != "HEAD" {
			http.Error(w, "Unimplemented HTTP method: use HEAD or GET.", http.StatusNotImplemented)
			return
		}
		// Fail if there are dots in the path
		if strings.Contains(r.URL.Path, "..") {
			http.Error(w, "Your directory traversal technique has been defeated!", http.StatusForbidden)
			return
		}
		// Resolve URI path to actual filesystem path
		path := r.URL.Path
		if strings.HasPrefix(path, "/~") {
		    bits := strings.Split(r.URL.Path, "/")
			username := bits[1][1:]
			//strings.Replace(bits[1], "~", "", 1)
			new_prefix := filepath.Join("home", username, config.HomeDocBase)
			path = strings.Replace(path, bits[1], new_prefix, 1)
		} else {
			path = filepath.Join(config.DocBase, r.URL.Path)
		}
		//fmt.Println(path)
		// Fail if file does not exist
		info, err := os.Stat(path)
		if os.IsNotExist(err) {
			http.Error(w, "Not found.", http.StatusNotFound)
			return
		}
		if os.IsPermission(err) {
			http.Error(w, "Permission denied.", http.StatusForbidden)
			return
		}
		// Handle URLS which map to a directory
		if info.IsDir() {
			// Redirect to add trailing slash if missing
			// (otherwise relative links don't work properly)
			if !strings.HasSuffix(r.URL.Path, "/") {
				http.Redirect(w, r, r.URL.String()+"/", http.StatusMovedPermanently)
				return
			}
			// Add index.html to directory paths, if it exists
			index_path := filepath.Join(path, "index.html")
			index_info, err := os.Stat(index_path)
			if !os.IsNotExist(err) {
				path = index_path
				info = index_info
			}
		}
		// Fail if file is not world readable
		if uint64(info.Mode().Perm())&0444 != 0444 {
			http.Error(w, "File not world-readable.", http.StatusForbidden)
			return
		}
		// If this is a directory, nothing below makes sense, so just
		// serve it!
		if info.IsDir() {
			http.ServeFile(w, r, path)
			return
		}

		// Get MIME type
		ext := filepath.Ext(path)
		mime := mime.TypeByExtension(ext)
		if mime == "" {
			http.Error(w, "MIME type detection error.", http.StatusInternalServerError)
			return
		}
		// Fail if MIME type is forbidden
		_, ok := config.BadMimesMap[mime]
		if ok {
			http.Error(w, "Forbidden MIME type: "+mime, http.StatusForbidden)
			return
		}
		// Fail if file is too large
		if !strings.HasPrefix(mime, "text/plain") && ((strings.HasPrefix(mime, "text/") && info.Size() > 1024*1024) ||
			info.Size() > 32*1024) {
			http.Error(w, "File too big: text/plain files have no limit, other text/* files may be up to 1 MiB, non-text files may be up to 32 KiB.", http.StatusForbidden)
			return
		}
		// Fail if a HTML file doesn't measure up
		if strings.HasPrefix(mime, "text/html") {
			reader, err := os.Open(path)
			if err != nil {
				http.Error(w, "Some kind of file error!", http.StatusInternalServerError)
				return
			}
			doc, err := html.Parse(reader)
			if err != nil {
				http.Error(w, "Some kind of HTML parsing error!", http.StatusInternalServerError)
				return
			}
			var imgcount int
			ok, msg := ValidateHtml(config, doc, 0, &imgcount)
			if ok == false {
				http.Error(w, "HTML document contains forbidden tag: "+msg, http.StatusForbidden)
				return
			}
		}
		// At this point everything is fine and we'll actually try to serve
		// the file.
		w.Header().Set("Content-Type", mime)
		http.ServeFile(w, r, path)
	}
}

func GetRedirectTLSHandler(config Config) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		// Don't redirect Let's Encrypt requests
		if strings.HasPrefix(r.URL.Path, "/.well-known/acme-challenge/") {
			path := filepath.Join(config.DocBase, r.URL.Path)
			http.ServeFile(w, r, path)
		// But redirect everything else
		} else {
			http.Redirect(w, r, "https://"+r.Host+r.RequestURI, http.StatusMovedPermanently)
		}
}	}