[WIP] Response tags

dmfr/feed_fetch.go

@@ -12,6 +12,7 @@ type FeedFetch struct {
 	ResponseSize  tl.Int
 	ResponseCode  tl.Int
 	ResponseSHA1  tl.String
+	ResponseETag  tl.String
 	FeedVersionID tl.Int // optional field, don't use tl.FeedVersionEntity
 	tl.Timestamps
 	tl.DatabaseEntity

tl/request/http.go

@@ -15,14 +15,19 @@ import (
 type Http struct{}
 
 func (r Http) Download(ctx context.Context, ustr string, secret tl.Secret, auth tl.FeedAuthorization) (io.ReadCloser, int, error) {
+	rc, code, _, err := r.ETagDownload(ctx, ustr, "", secret, auth)
+	return rc, code, err
+}
+
+func (r Http) ETagDownload(ctx context.Context, ustr string, etag string, secret tl.Secret, auth tl.FeedAuthorization) (io.ReadCloser, int, string, error) {
 	u, err := url.Parse(ustr)
 	if err != nil {
-		return nil, 0, errors.New("could not parse url")
+		return nil, 0, "", errors.New("could not parse url")
 	}
 	if auth.Type == "query_param" {
 		v, err := url.ParseQuery(u.RawQuery)
 		if err != nil {
-			return nil, 0, errors.New("could not parse query string")
+			return nil, 0, "", errors.New("could not parse query string")
 		}
 		v.Set(auth.ParamName, secret.Key)
 		u.RawQuery = v.Encode()
@@ -31,15 +36,15 @@ func (r Http) Download(ctx context.Context, ustr string, secret tl.Secret, auth
 	} else if auth.Type == "replace_url" {
 		u, err = url.Parse(secret.ReplaceUrl)
 		if err != nil {
-			return nil, 0, errors.New("could not parse replacement query string")
+			return nil, 0, "", errors.New("could not parse replacement query string")
 		}
 	}
 	ustr = u.String()
 
 	// Prepare HTTP request
 	req, err := http.NewRequestWithContext(ctx, "GET", ustr, nil)
 	if err != nil {
-		return nil, 0, errors.New("invalid request")
+		return nil, 0, "", errors.New("invalid request")
 	}
 
 	// Set basic auth, if used
@@ -56,11 +61,11 @@ func (r Http) Download(ctx context.Context, ustr string, secret tl.Secret, auth
 	resp, err := client.Do(req)
 	if err != nil {
 		// return error directly
-		return nil, 0, err
+		return nil, 0, "", err
 	}
 	if resp.StatusCode >= 400 {
 		resp.Body.Close()
-		return nil, resp.StatusCode, fmt.Errorf("response status code: %d", resp.StatusCode)
+		return nil, resp.StatusCode, "", fmt.Errorf("response status code: %d", resp.StatusCode)
 	}
-	return resp.Body, resp.StatusCode, nil
+	return resp.Body, resp.StatusCode, resp.Header.Get("ETag"), nil
 }

tl/request/request.go

@@ -21,6 +21,10 @@ type Downloader interface {
 	Download(context.Context, string, tl.Secret, tl.FeedAuthorization) (io.ReadCloser, int, error)
 }
 
+type ETagDownloader interface {
+	ETagDownload(context.Context, string, string, tl.Secret, tl.FeedAuthorization) (io.ReadCloser, int, string, error)
+}
+
 type Uploader interface {
 	Upload(context.Context, string, tl.Secret, io.Reader) error
 }
@@ -29,11 +33,22 @@ type Presigner interface {
 	CreateSignedUrl(context.Context, string, tl.Secret) (string, error)
 }
 
+type FetchResponse struct {
+	Filename     string
+	Data         []byte
+	ResponseSize int
+	ResponseCode int
+	ResponseSHA1 string
+	ResponseETag string
+	FetchError   error
+}
+
 type Request struct {
 	URL        string
 	AllowFTP   bool
 	AllowLocal bool
 	AllowS3    bool
+	CheckETag  string
 	MaxSize    uint64
 	Secret     tl.Secret
 	Auth       tl.FeedAuthorization
@@ -126,15 +141,6 @@ func WithAuth(secret tl.Secret, auth tl.FeedAuthorization) func(req *Request) {
 	}
 }
 
-type FetchResponse struct {
-	Filename     string
-	Data         []byte
-	ResponseSize int
-	ResponseCode int
-	ResponseSHA1 string
-	FetchError   error
-}
-
 // AuthenticatedRequestDownload is similar to AuthenticatedRequest but writes to a temporary file.
 // Fatal errors will be returned as the error; non-fatal errors as FetchResponse.FetchError
 func AuthenticatedRequestDownload(address string, opts ...RequestOption) (FetchResponse, error) {
@@ -182,7 +188,7 @@ func authenticatedRequest(out io.Writer, address string, opts ...RequestOption)
 	fr := FetchResponse{}
 	req := NewRequest(address, opts...)
 	var r io.ReadCloser
-	r, fr.ResponseCode, fr.FetchError = req.Request(ctx)
+	r, fr.ResponseCode, fr.ResponseETag, fr.FetchError = req.Request(ctx)
 	if fr.FetchError != nil {
 		return fr, nil
 	}

tl/request/request_test.go

@@ -1,6 +1,8 @@
 package request
 
 import (
+	"crypto/md5"
+	"encoding/hex"
 	"encoding/json"
 	"net/http"
 	"net/http/httptest"
@@ -25,6 +27,10 @@ func TestAuthorizedRequest(t *testing.T) {
 			http.Error(w, err.Error(), 400)
 			return
 		}
+		h := md5.New() // So it's distinct from checksha1
+		h.Write(a)
+		etag := hex.EncodeToString(h.Sum(nil))
+		w.Header().Add("ETag", etag)
 		w.Header().Add("Status-Code", "200")
 		w.Write(a)
 	}))
@@ -38,6 +44,7 @@ func TestAuthorizedRequest(t *testing.T) {
 		checksize   int
 		checkcode   int
 		checksha1   string
+		checketag   string
 		expectError bool
 		secret      tl.Secret
 	}{
@@ -50,6 +57,7 @@ func TestAuthorizedRequest(t *testing.T) {
 			checksize:  29,
 			checkcode:  200,
 			checksha1:  "66621b979e91314ea163d94be8e7486bdcfe07c9",
+			checketag:  "f72666cd1f7a71508c6e81ac007c90bb",
 		},
 		{
 			name:       "query_param",
@@ -70,7 +78,8 @@ func TestAuthorizedRequest(t *testing.T) {
 			checkvalue: "/anything/abcd/ok",
 			checksize:  0,
 			checkcode:  200,
-			checksha1:  "",
+			checksha1:  "22c2326192e08c5659ce99dcee454c86ed3fa09e",
+			checketag:  "b820d771af0771269aae463658d4992a",
 			secret:     tl.Secret{Key: "abcd"},
 		},
 		{
@@ -145,6 +154,9 @@ func TestAuthorizedRequest(t *testing.T) {
 			if tc.checksha1 != "" {
 				assert.Equal(t, tc.checksha1, fr.ResponseSHA1, "did not match expected sha1")
 			}
+			if tc.checketag != "" {
+				assert.Equal(t, tc.checketag, fr.ResponseETag, "did not match expected etag")
+			}
 			if tc.checkkey != "" {
 				a, ok := result[tc.checkkey].(string)
 				if !ok {