Add decode flag for GetBlob() by reworking codec layer (#592)

api/clients/codecs/blob_codec.go

@@ -20,8 +20,26 @@ type BlobCodec interface {
 func BlobEncodingVersionToCodec(version BlobEncodingVersion) (BlobCodec, error) {
 	switch version {
 	case DefaultBlobEncoding:
-		return DefaultBlobEncodingCodec{}, nil
+		return DefaultBlobCodec{}, nil
 	default:
 		return nil, fmt.Errorf("unsupported blob encoding version: %x", version)
 	}
 }
+
+func GenericDecodeBlob(data []byte) ([]byte, error) {
+	if len(data) <= 32 {
+		return nil, fmt.Errorf("data is not of length greater than 32 bytes: %d", len(data))
+	}
+	version := BlobEncodingVersion(data[1])
+	codec, err := BlobEncodingVersionToCodec(version)
+	if err != nil {
+		return nil, err
+	}
+
+	data, err = codec.DecodeBlob(data)
+	if err != nil {
+		return nil, err
+	}
+
+	return data, nil
+}

api/clients/codecs/encodings_test.go → api/clients/codecs/blob_codec_test.go

@@ -19,10 +19,45 @@ func randomByteSlice(length int64) []byte {
 	return b
 }
 
-// TestDefaultBlobEncodingCodec tests the encoding and decoding of random byte streams
-func TestDefaultBlobEncodingCodec(t *testing.T) {
+// TestIFFTCodec tests the encoding and decoding of random byte streams
+func TestIFFTCodec(t *testing.T) {
 	// Create an instance of the DefaultBlobEncodingCodec
-	codec := codecs.DefaultBlobEncodingCodec{}
+	codec := codecs.NewIFFTCodec(codecs.NewDefaultBlobCodec())
+
+	// Number of test iterations
+	const iterations = 100
+
+	for i := 0; i < iterations; i++ {
+		// Generate a random length for the byte slice
+		length, err := rand.Int(rand.Reader, big.NewInt(1024)) // Random length between 0 and 1023
+		if err != nil {
+			panic(err)
+		}
+		originalData := randomByteSlice(length.Int64() + 1) // ensure it's not length 0
+
+		// Encode the original data
+		encodedData, err := codec.EncodeBlob(originalData)
+		if err != nil {
+			t.Fatalf("Iteration %d: failed to encode blob: %v", i, err)
+		}
+
+		// Decode the encoded data
+		decodedData, err := codec.DecodeBlob(encodedData)
+		if err != nil {
+			t.Fatalf("Iteration %d: failed to decode blob: %v", i, err)
+		}
+
+		// Compare the original data with the decoded data
+		if !bytes.Equal(originalData, decodedData) {
+			t.Fatalf("Iteration %d: original and decoded data do not match\nOriginal: %v\nDecoded: %v", i, originalData, decodedData)
+		}
+	}
+}
+
+// TestIFFTCodec tests the encoding and decoding of random byte streams
+func TestNoIFFTCodec(t *testing.T) {
+	// Create an instance of the DefaultBlobEncodingCodec
+	codec := codecs.NewNoIFFTCodec(codecs.NewDefaultBlobCodec())
 
 	// Number of test iterations
 	const iterations = 100

api/clients/codecs/default_blob_codec.go

@@ -0,0 +1,59 @@
+package codecs
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+
+	"github.com/Layr-Labs/eigenda/encoding/utils/codec"
+)
+
+type DefaultBlobCodec struct{}
+
+var _ BlobCodec = DefaultBlobCodec{}
+
+func NewDefaultBlobCodec() DefaultBlobCodec {
+	return DefaultBlobCodec{}
+}
+
+func (v DefaultBlobCodec) EncodeBlob(rawData []byte) ([]byte, error) {
+	codecBlobHeader := make([]byte, 32)
+	// first byte is always 0 to ensure the codecBlobHeader is a valid bn254 element
+	// encode version byte
+	codecBlobHeader[1] = byte(DefaultBlobEncoding)
+
+	// encode length as uint32
+	binary.BigEndian.PutUint32(codecBlobHeader[2:6], uint32(len(rawData))) // uint32 should be more than enough to store the length (approx 4gb)
+
+	// encode raw data modulo bn254
+	rawDataPadded := codec.ConvertByPaddingEmptyByte(rawData)
+
+	// append raw data
+	encodedData := append(codecBlobHeader, rawDataPadded...)
+
+	return encodedData, nil
+}
+
+func (v DefaultBlobCodec) DecodeBlob(data []byte) ([]byte, error) {
+	if len(data) < 32 {
+		return nil, fmt.Errorf("blob does not contain 32 header bytes, meaning it is malformed")
+	}
+
+	length := binary.BigEndian.Uint32(data[2:6])
+
+	// decode raw data modulo bn254
+	decodedData := codec.RemoveEmptyByteFromPaddedBytes(data[32:])
+
+	// get non blob header data
+	reader := bytes.NewReader(decodedData)
+	rawData := make([]byte, length)
+	n, err := reader.Read(rawData)
+	if err != nil {
+		return nil, fmt.Errorf("failed to copy unpadded data into final buffer, length: %d, bytes read: %d", length, n)
+	}
+	if uint32(n) != length {
+		return nil, fmt.Errorf("data length does not match length prefix")
+	}
+
+	return rawData, nil
+}

api/clients/eigenda_client_utils.go → api/clients/codecs/fft.go

@@ -1,4 +1,4 @@
-package clients
+package codecs
 
 import (
 	"fmt"

api/clients/codecs/ifft_codec.go

@@ -0,0 +1,38 @@
+package codecs
+
+import "fmt"
+
+type IFFTCodec struct {
+	writeCodec BlobCodec
+}
+
+var _ BlobCodec = IFFTCodec{}
+
+func NewIFFTCodec(writeCodec BlobCodec) IFFTCodec {
+	return IFFTCodec{
+		writeCodec: writeCodec,
+	}
+}
+
+func (v IFFTCodec) EncodeBlob(data []byte) ([]byte, error) {
+	var err error
+	data, err = v.writeCodec.EncodeBlob(data)
+	if err != nil {
+		return nil, fmt.Errorf("error encoding data: %w", err)
+	}
+
+	return IFFT(data)
+}
+
+func (v IFFTCodec) DecodeBlob(data []byte) ([]byte, error) {
+	if len(data) == 0 {
+		return nil, fmt.Errorf("blob has length 0, meaning it is malformed")
+	}
+	var err error
+	data, err = FFT(data)
+	if err != nil {
+		return nil, fmt.Errorf("error FFTing data: %w", err)
+	}
+
+	return GenericDecodeBlob(data)
+}

api/clients/codecs/no_ifft_codec.go

@@ -0,0 +1,21 @@
+package codecs
+
+type NoIFFTCodec struct {
+	writeCodec BlobCodec
+}
+
+var _ BlobCodec = NoIFFTCodec{}
+
+func NewNoIFFTCodec(writeCodec BlobCodec) NoIFFTCodec {
+	return NoIFFTCodec{
+		writeCodec: writeCodec,
+	}
+}
+
+func (v NoIFFTCodec) EncodeBlob(data []byte) ([]byte, error) {
+	return v.writeCodec.EncodeBlob(data)
+}
+
+func (v NoIFFTCodec) DecodeBlob(data []byte) ([]byte, error) {
+	return GenericDecodeBlob(data)
+}