Improve detecting base64 encoded attachments

wormi4ok · Mar 4, 2023 · 3c11c35 · 3c11c35
1 parent 3b5a5a1
commit 3c11c35
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Showing 3 changed files with 62 additions and 9 deletions.
diff --git a/go.sum b/go.sum
@@ -33,32 +33,25 @@ github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZN
 github.com/rivo/uniseg v0.1.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
 github.com/rivo/uniseg v0.2.0 h1:S1pD9weZBuJdFmowNwbpi7BJ8TNftyUImj/0WQi72jY=
 github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
-github.com/sergi/go-diff v1.2.0 h1:XU+rvMAioB0UC3q1MFrIQy4Vo5/4VsRDQQXHsEya6xQ=
-github.com/sergi/go-diff v1.2.0/go.mod h1:STckp+ISIX8hZLjrqAeVduY0gWCT9IjLuqbuNXdaHfM=
 github.com/sergi/go-diff v1.3.1 h1:xkr+Oxo4BOQKmkn/B9eMK0g5Kg/983T9DqqPHwYqD+8=
 github.com/sergi/go-diff v1.3.1/go.mod h1:aMJSSKb2lpPvRNec0+w3fl7LP9IOFzdc9Pa4NFbPK1I=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/wormi4ok/godown v0.4.0 h1:baxURAO0WuaEd06fo5WkgosHUwjQSJuV3wnnx28G0zs=
 github.com/wormi4ok/godown v0.4.0/go.mod h1:LPSYhfL9Q6QZXNyT43NPdZzY3Yb7qKsbjM9ke/SR4+A=
-golang.org/x/net v0.4.0 h1:Q5QPcMlvfxFTAPV0+07Xz/MpK9NTXu2VDUuy0FeMfaU=
-golang.org/x/net v0.4.0/go.mod h1:MBQ8lrhLObU/6UmLb4fmbmk5OcyYmqtbGd/9yIeKjEE=
 golang.org/x/net v0.5.0 h1:GyT4nK/YDHSqa1c4753ouYCDajOYKTja9Xb/OHtgvSw=
 golang.org/x/net v0.5.0/go.mod h1:DivGGAXEgPSlEBzxGzZI+ZLohi+xUj054jfeKui00ws=
 golang.org/x/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200223170610-d5e6a3e2c0ae/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210927094055-39ccf1dd6fa6/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220503163025-988cb79eb6c6/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.3.0 h1:w8ZOecv6NaNa/zC8944JTU3vz4u6Lagfk4RPQxv92NQ=
-golang.org/x/sys v0.3.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.4.0 h1:Zr2JFtRQNX3BCZ8YtxRE9hNJYC8J6I1MVbMg6owUp18=
 golang.org/x/sys v0.4.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gopkg.in/yaml.v2 v2.2.4 h1:/eiJrUcujPVeJ3xlSWaiNi3uSVmDGBK1pDHUHAnao1I=
-gopkg.in/yaml.v2 v2.2.4/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
diff --git a/internal/resource.go b/internal/resource.go
@@ -17,14 +17,20 @@ var reImg = regexp.MustCompile(`^image/[\w]+`)
 
 var reFileAndExt = regexp.MustCompile(`(.*)(\.[\w\d]+)`)
 
+var reBase64 = regexp.MustCompile(`^([A-Za-z0-9+/]{4})*([A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{2}==)?$`)
+
 func decoder(d enex.Data) io.Reader {
-	if d.Encoding == "base64" {
+	if d.Encoding == "base64" || isBase64Encoded(d.Content) {
 		return base64.NewDecoder(base64.StdEncoding, bytes.NewReader(bytes.TrimSpace(d.Content)))
 	}
 
 	return bytes.NewReader(d.Content)
 }
 
+func isBase64Encoded(content []byte) bool {
+	return reBase64.Match(content)
+}
+
 func isImage(mimeType string) bool {
 	return reImg.MatchString(mimeType)
 }

diff --git a/internal/resource_test.go b/internal/resource_test.go
@@ -1,6 +1,9 @@
 package internal
 
 import (
+	"bytes"
+	"encoding/base64"
+	"io"
 	"testing"
 
 	"github.com/wormi4ok/evernote2md/encoding/enex"
@@ -48,3 +51,54 @@ func Test_guessName(t *testing.T) {
 		})
 	}
 }
+
+func Test_decoder(t *testing.T) {
+	want := []byte("sample text")
+	encoded := new(bytes.Buffer)
+	b64encoder := base64.NewEncoder(base64.StdEncoding, encoded)
+
+	if _, err := b64encoder.Write(want); err != nil {
+		t.Error(err)
+	}
+	if err := b64encoder.Close(); err != nil {
+		t.Error(err)
+	}
+
+	tests := []struct {
+		name string
+		data enex.Data
+	}{
+		{
+			name: "not encoded",
+			data: enex.Data{
+				Encoding: "",
+				Content:  want,
+			},
+		},
+		{
+			name: "base64 encoded",
+			data: enex.Data{
+				Encoding: "base64",
+				Content:  encoded.Bytes(),
+			},
+		},
+		{
+			name: "base64 encoded - encoding value missing",
+			data: enex.Data{
+				Encoding: "",
+				Content:  encoded.Bytes(),
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := io.ReadAll(decoder(tt.data))
+			if err != nil {
+				t.Error(err)
+			}
+			if !bytes.Equal(got, want) {
+				t.Errorf("decoder() = %s, want %s", got, want)
+			}
+		})
+	}
+}