Draft: Allow to trim input lines when writing PGP messages

crypto/encrypt_decrypt_test.go

@@ -924,6 +924,32 @@ func TestEncryptDecryptKey(t *testing.T) {
 	}
 }
 
+func TestEncryptDecryptStreamTrimmedLines(t *testing.T) {
+	for _, material := range testMaterialForProfiles {
+		t.Run(material.profileName, func(t *testing.T) {
+			encHandle, _ := material.pgp.Encryption().
+				Recipients(material.keyRingTestPublic).
+				SigningKeys(material.keyRingTestPrivate).
+				TrimLines().
+				New()
+			decHandle, _ := material.pgp.Decryption().
+				DecryptionKeys(material.keyRingTestPrivate).
+				VerificationKeys(material.keyRingTestPublic).
+				New()
+			testEncryptDecryptStreamWithExpected(
+				t,
+				[]byte("text with   \r \t \n trimmed\n   \t"),
+				[]byte("text with\n trimmed\n"),
+				nil,
+				encHandle,
+				decHandle,
+				len(material.keyRingTestPrivate.entities),
+				Bytes,
+			)
+		})
+	}
+}
+
 func TestEncryptCompressionApplied(t *testing.T) {
 	const numReplicas = 10
 	builder := strings.Builder{}
@@ -1169,6 +1195,28 @@ func testEncryptDecryptStream(
 	decHandle PGPDecryption,
 	numberOfSigsToVerify int,
 	encoding int8,
+) {
+	testEncryptDecryptStreamWithExpected(
+		t,
+		messageBytes,
+		messageBytes,
+		metadata,
+		encHandle,
+		decHandle,
+		numberOfSigsToVerify,
+		encoding,
+	)
+}
+
+func testEncryptDecryptStreamWithExpected(
+	t *testing.T,
+	messageBytes []byte,
+	expected []byte,
+	metadata *LiteralMetadata,
+	encHandle PGPEncryption,
+	decHandle PGPDecryption,
+	numberOfSigsToVerify int,
+	encoding int8,
 ) {
 	messageReader := bytes.NewReader(messageBytes)
 	var ciphertextBuf bytes.Buffer
@@ -1200,7 +1248,7 @@ func testEncryptDecryptStream(
 	if err != nil {
 		t.Fatal("Expected no error while reading the decrypted data, got:", err)
 	}
-	if !bytes.Equal(decryptedBytes, messageBytes) {
+	if !bytes.Equal(decryptedBytes, expected) {
 		t.Fatalf("Expected the decrypted data to be %s got %s", string(decryptedBytes), string(messageBytes))
 	}
 	if numberOfSigsToVerify > 0 {

crypto/encryption_handle.go

@@ -55,6 +55,9 @@ type encryptionHandle struct {
 	// Is only considered if DetachedSignature is not set.
 	PlainDetachedSignature bool
 	IsUTF8                 bool
+	// TrimLines trims each end of the line in the input message before encryption.
+	// Remove trailing spaces, carriage returns and tabs from each line (separated by \n characters).
+	TrimLines bool
 	// ExternalSignature allows to include an external signature into
 	// the encrypted message.
 	ExternalSignature []byte
@@ -332,6 +335,9 @@ func (eh *encryptionHandle) encryptingWriters(keys, data, detachedSignature Writ
 			openpgp.NewCanonicalTextWriteCloser(messageWriter),
 		)
 	}
+	if eh.TrimLines {
+		messageWriter = internal.NewTrimWriteCloser(messageWriter)
+	}
 	return messageWriter, nil
 }
 

crypto/encryption_handle_builder.go

@@ -148,6 +148,13 @@ func (ehb *EncryptionHandleBuilder) Utf8() *EncryptionHandleBuilder {
 	return ehb
 }
 
+// TrimLines enables that each line in the input message is trimmed before encryption.
+// Trim removes trailing spaces, carriage returns and tabs from each line (separated by \n characters).
+func (ehb *EncryptionHandleBuilder) TrimLines() *EncryptionHandleBuilder {
+	ehb.handle.TrimLines = true
+	return ehb
+}
+
 // DetachedSignature indicates that the message should be signed,
 // but the signature should not be included in the same pgp message as the input data.
 // Instead the detached signature is encrypted in a separate pgp message.

crypto/sign_handle.go

@@ -16,10 +16,13 @@ import (
 )
 
 type signatureHandle struct {
-	SignKeyRing  *KeyRing
-	SignContext  *SigningContext
-	IsUTF8       bool
-	Detached     bool
+	SignKeyRing *KeyRing
+	SignContext *SigningContext
+	IsUTF8      bool
+	Detached    bool
+	// TrimLines trims each end of the line in the input message before encryption.
+	// Remove trailing spaces, carriage returns and tabs from each line (separated by \n characters).
+	TrimLines    bool
 	ArmorHeaders map[string]string
 	profile      SignProfile
 	clock        Clock
@@ -87,6 +90,9 @@ func (sh *signatureHandle) SigningWriter(outputWriter Writer, encoding int8) (me
 			openpgp.NewCanonicalTextWriteCloser(messageWriter),
 		)
 	}
+	if sh.TrimLines {
+		messageWriter = internal.NewTrimWriteCloser(messageWriter)
+	}
 	return messageWriter, nil
 }
 

crypto/sign_handle_builder.go

@@ -68,6 +68,13 @@ func (shb *SignHandleBuilder) Utf8() *SignHandleBuilder {
 	return shb
 }
 
+// TrimLines enables that each line in the input message is trimmed before encryption.
+// Trim removes trailing spaces, carriage returns and tabs from each line (separated by \n characters).
+func (shb *SignHandleBuilder) TrimLines() *SignHandleBuilder {
+	shb.handle.TrimLines = true
+	return shb
+}
+
 // SignTime sets the internal clock to always return
 // the supplied unix time for signing instead of the device time.
 func (shb *SignHandleBuilder) SignTime(unixTime int64) *SignHandleBuilder {

internal/trim_lines_writer.go

@@ -0,0 +1,89 @@
+package internal
+
+import (
+	"bytes"
+	"io"
+)
+
+func trim(p []byte) []byte {
+	return bytes.TrimRight(p, " \t\r")
+}
+
+func NewTrimWriteCloser(internal io.WriteCloser) *TrimWriteCloser {
+	return NewTrimWriteCloserWithBufferSize(internal, 256)
+}
+
+func NewTrimWriteCloserWithBufferSize(internal io.WriteCloser, size int) *TrimWriteCloser {
+	return &TrimWriteCloser{
+		internal:   internal,
+		whitespace: bytes.NewBuffer(make([]byte, 0, size)),
+		err:        nil,
+	}
+}
+
+type TrimWriteCloser struct {
+	internal   io.WriteCloser
+	whitespace *bytes.Buffer
+	err        error
+}
+
+func (w *TrimWriteCloser) Write(p []byte) (n int, err error) {
+	n = len(p)
+	if w.err != nil {
+		return 0, err
+	}
+	for index := bytes.IndexByte(p, '\n'); index != -1; index = bytes.IndexByte(p, '\n') {
+		trimmedSuffixLine := trim(p[:index])
+		bufferWhitespace := w.whitespace.Bytes()
+		if len(bufferWhitespace) > 0 {
+			if len(trimmedSuffixLine) != 0 {
+				if _, err = w.internal.Write(bufferWhitespace); err != nil {
+					w.err = err
+					return 0, err
+				}
+			}
+			w.whitespace.Reset()
+		}
+		if len(trimmedSuffixLine) < len(p[:index]) {
+			if _, err = w.internal.Write(trimmedSuffixLine); err != nil {
+				w.err = err
+				return index, err
+			}
+			if _, err = w.internal.Write([]byte("\n")); err != nil {
+				w.err = err
+				return index + 1, err
+			}
+		} else {
+			if _, err = w.internal.Write(p[:index+1]); err != nil {
+				w.err = err
+				return index + 1, err
+			}
+		}
+		p = p[index+1:]
+	}
+
+	if len(p) > 0 {
+		nonWhitespace := trim(p)
+		if len(nonWhitespace) > 0 && w.whitespace.Len() > 0 {
+			if _, err = w.internal.Write(w.whitespace.Bytes()); err != nil {
+				w.err = err
+				return n - len(p), err
+			}
+			w.whitespace.Reset()
+		}
+		if _, err = w.internal.Write(nonWhitespace); err != nil {
+			w.err = err
+			return n - len(p), err
+		}
+
+		if _, err = w.whitespace.Write(p[len(nonWhitespace):]); err != nil {
+			w.err = err
+			return n - len(p), err
+		}
+	}
+	return n, nil
+}
+
+func (w *TrimWriteCloser) Close() error {
+	return w.internal.Close()
+}

internal/trim_lines_writer_test.go

@@ -0,0 +1,41 @@
+package internal
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func testTrimWriteCloser(t *testing.T, test string) {
+	testBytes := []byte(test)
+	for _, batchSize := range []int{1, 2, 3, 7, 11} {
+		var buff bytes.Buffer
+		w := &noOpWriteCloser{
+			writer: &buff,
+		}
+		trimWriter := NewTrimWriteCloser(w)
+		for ind := 0; ind < len(testBytes); ind += batchSize {
+			end := ind + batchSize
+			if end > len(testBytes) {
+				end = len(testBytes)
+			}
+			if _, err := trimWriter.Write(testBytes[ind:end]); err != nil {
+				t.Fatal(err)
+			}
+		}
+		if err := trimWriter.Close(); err != nil {
+			t.Fatal(err)
+		}
+		assert.Equal(t, TrimEachLine(test), buff.String())
+	}
+}
+
+func TestTrimWriteCloser(t *testing.T) {
+	testTrimWriteCloser(t, "\n    \t     \r")
+	testTrimWriteCloser(t, "this is a test \n   \t \n\n")
+	testTrimWriteCloser(t, "saf\n   \t sdf\n \r\rsd   \t fsdf\n")
+	testTrimWriteCloser(t, "BEGIN:VCARD\r\nVERSION:4.0\r\nFN;PREF=1:   \r\nEND:VCARD")
+	testTrimWriteCloser(t, strings.Repeat("\r \nthis is a test \n   \t \n\n)", 10000))
+}

internal/utf8.go

@@ -164,19 +164,15 @@ func NewUtf8CheckWriteCloser(wrap io.WriteCloser) *Utf8CheckWriteCloser {
 }
 
 func (cw *Utf8CheckWriteCloser) Write(p []byte) (n int, err error) {
-	err = cw.check(p)
-	if err != nil {
-		return
+	if err = cw.check(p); err != nil {
+		return 0, err
 	}
-	n, err = cw.internal.Write(p)
-	return
+	return cw.internal.Write(p)
 }
 
 func (cw *Utf8CheckWriteCloser) Close() (err error) {
-	err = cw.close()
-	if err != nil {
-		return
+	if err = cw.close(); err != nil {
+		return err
 	}
-	err = cw.internal.Close()
-	return
+	return cw.internal.Close()
 }