finnally doooo and close #11

Former-commit-id: b899f43722862ed4aafbca659670f26011ae727d [formerly 746709cdc2fa58bc69a71fa795a5589a1145d853] [formerly 5aab2327e90c4dd0a47b71d8ef90043e8918db06 [formerly eb22fd20ce78b48c6a2a3c3ffc59b1ca76feda5e]]
Former-commit-id: ca8b01af19ef3bbd870636170f60fd7ae8e4cd7f [formerly be235a498e36298e07f1b5d07939668d57e08fe2]
Former-commit-id: 6bccf20702c8b3867a3a2ebae711834a740a06ad

handlers/checksum.go

@@ -0,0 +1,54 @@
+package handlers
+
+import (
+	"crypto/md5"
+	"crypto/sha1"
+	"crypto/sha256"
+	"crypto/sha512"
+	"encoding/hex"
+	e "errors"
+	"hash"
+	"io"
+	"net/http"
+	"os"
+
+	"github.com/hacdias/caddy-filemanager/config"
+	"github.com/hacdias/caddy-filemanager/file"
+	"github.com/hacdias/caddy-filemanager/utils/errors"
+)
+
+// Checksum calculates the hash of a file. Supports MD5, SHA1, SHA256 and SHA512.
+func Checksum(w http.ResponseWriter, r *http.Request, c *config.Config, i *file.Info) (int, error) {
+	query := r.URL.Query().Get("checksum")
+
+	file, err := os.Open(i.Path)
+	if err != nil {
+		return errors.ErrorToHTTPCode(err, true), err
+	}
+
+	defer file.Close()
+
+	var h hash.Hash
+
+	switch query {
+	case "md5":
+		h = md5.New()
+	case "sha1":
+		h = sha1.New()
+	case "sha256":
+		h = sha256.New()
+	case "sha512":
+		h = sha512.New()
+	default:
+		return http.StatusBadRequest, e.New("Unknown HASH type")
+	}
+
+	_, err = io.Copy(h, file)
+	if err != nil {
+		return http.StatusInternalServerError, err
+	}
+
+	val := hex.EncodeToString(h.Sum(nil))
+	w.Write([]byte(val))
+	return http.StatusOK, nil
+}