From 25678476dbf2073a26ea16adc05f28aee811c66d Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Mon, 3 Feb 2020 21:48:31 +0100
Subject: [PATCH] internal: add ETag

---
 caldav/client.go     |  7 +------
 carddav/client.go    |  7 +------
 carddav/server.go    |  2 +-
 client.go            |  7 +------
 internal/elements.go | 21 ++++++++++++++++++++-
 server.go            |  5 ++---
 6 files changed, 26 insertions(+), 23 deletions(-)

diff --git a/caldav/client.go b/caldav/client.go
index f7606a8..f433b65 100644
--- a/caldav/client.go
+++ b/caldav/client.go
@@ -3,7 +3,6 @@ package caldav
 import (
 	"fmt"
 	"net/http"
-	"strconv"
 	"time"
 
 	"github.com/emersion/go-webdav"
@@ -164,15 +163,11 @@ func decodeCalendarObjectList(ms *internal.Multistatus) ([]CalendarObject, error
 		if err := resp.DecodeProp(&getETag); err != nil && !internal.IsNotFound(err) {
 			return nil, err
 		}
-		etag, err := strconv.Unquote(getETag.ETag)
-		if err != nil {
-			return nil, fmt.Errorf("carddav: failed to unquote ETag: %v", err)
-		}
 
 		addrs = append(addrs, CalendarObject{
 			Path:    path,
 			ModTime: time.Time(getLastMod.LastModified),
-			ETag:    etag,
+			ETag:    string(getETag.ETag),
 			Data:    calData.Data,
 		})
 	}
diff --git a/carddav/client.go b/carddav/client.go
index e89511f..b939760 100644
--- a/carddav/client.go
+++ b/carddav/client.go
@@ -6,7 +6,6 @@ import (
 	"net"
 	"net/http"
 	"net/url"
-	"strconv"
 	"strings"
 	"time"
 
@@ -222,10 +221,6 @@ func decodeAddressList(ms *internal.Multistatus) ([]AddressObject, error) {
 		if err := resp.DecodeProp(&getETag); err != nil && !internal.IsNotFound(err) {
 			return nil, err
 		}
-		etag, err := strconv.Unquote(getETag.ETag)
-		if err != nil {
-			return nil, fmt.Errorf("carddav: failed to unquote ETag: %v", err)
-		}
 
 		r := bytes.NewReader(addrData.Data)
 		card, err := vcard.NewDecoder(r).Decode()
@@ -236,7 +231,7 @@ func decodeAddressList(ms *internal.Multistatus) ([]AddressObject, error) {
 		addrs = append(addrs, AddressObject{
 			Path:    path,
 			ModTime: time.Time(getLastMod.LastModified),
-			ETag:    etag,
+			ETag:    string(getETag.ETag),
 			Card:    card,
 		})
 	}
diff --git a/carddav/server.go b/carddav/server.go
index 494719c..28d14f8 100644
--- a/carddav/server.go
+++ b/carddav/server.go
@@ -372,7 +372,7 @@ func (b *backend) propfindAddressObject(propfind *internal.Propfind, ao *Address
 
 	if ao.ETag != "" {
 		props[internal.GetETagName] = func(*internal.RawXMLValue) (interface{}, error) {
-			return &internal.GetETag{ETag: fmt.Sprintf("%q", ao.ETag)}, nil
+			return &internal.GetETag{ETag: internal.ETag(ao.ETag)}, nil
 		}
 	}
 
diff --git a/client.go b/client.go
index da08656..02dbccf 100644
--- a/client.go
+++ b/client.go
@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"io"
 	"net/http"
-	"strconv"
 	"time"
 
 	"github.com/emersion/go-webdav/internal"
@@ -88,15 +87,11 @@ func fileInfoFromResponse(resp *internal.Response) (*FileInfo, error) {
 		if err := resp.DecodeProp(&getETag); err != nil && !internal.IsNotFound(err) {
 			return nil, err
 		}
-		etag, err := strconv.Unquote(getETag.ETag)
-		if err != nil {
-			return nil, fmt.Errorf("webdav: failed to unquote ETag: %v", err)
-		}
 
 		fi.Size = getLen.Length
 		fi.ModTime = time.Time(getMod.LastModified)
 		fi.MIMEType = getType.Type
-		fi.ETag = etag
+		fi.ETag = string(getETag.ETag)
 	}
 
 	return fi, nil
diff --git a/internal/elements.go b/internal/elements.go
index accb6de..324deae 100644
--- a/internal/elements.go
+++ b/internal/elements.go
@@ -342,7 +342,26 @@ type GetLastModified struct {
 // https://tools.ietf.org/html/rfc4918#section-15.6
 type GetETag struct {
 	XMLName xml.Name `xml:"DAV: getetag"`
-	ETag    string   `xml:",chardata"`
+	ETag    ETag     `xml:",chardata"`
+}
+
+type ETag string
+
+func (etag *ETag) UnmarshalText(b []byte) error {
+	s, err := strconv.Unquote(string(b))
+	if err != nil {
+		return fmt.Errorf("webdav: failed to unquote ETag: %v", err)
+	}
+	*etag = ETag(s)
+	return nil
+}
+
+func (etag *ETag) MarshalText() ([]byte, error) {
+	return []byte(fmt.Sprintf("%q", *etag)), nil
+}
+
+func (etag ETag) String() string {
+	return string(etag)
 }
 
 // https://tools.ietf.org/html/rfc4918#section-14.5
diff --git a/server.go b/server.go
index f1a326f..811ef10 100644
--- a/server.go
+++ b/server.go
@@ -2,7 +2,6 @@ package webdav
 
 import (
 	"encoding/xml"
-	"fmt"
 	"io"
 	"net/http"
 	"os"
@@ -93,7 +92,7 @@ func (b *backend) HeadGet(w http.ResponseWriter, r *http.Request) error {
 		w.Header().Set("Last-Modified", fi.ModTime.UTC().Format(http.TimeFormat))
 	}
 	if fi.ETag != "" {
-		w.Header().Set("ETag", fmt.Sprintf("%q", fi.ETag))
+		w.Header().Set("ETag", internal.ETag(fi.ETag).String())
 	}
 
 	if rs, ok := f.(io.ReadSeeker); ok {
@@ -174,7 +173,7 @@ func (b *backend) propfindFile(propfind *internal.Propfind, fi *FileInfo) (*inte
 
 		if fi.ETag != "" {
 			props[internal.GetETagName] = func(*internal.RawXMLValue) (interface{}, error) {
-				return &internal.GetETag{ETag: fmt.Sprintf("%q", fi.ETag)}, nil
+				return &internal.GetETag{ETag: internal.ETag(fi.ETag)}, nil
 			}
 		}
 	}