Add kzgpad util for using grpcurl to test eigenda

Makefile

@@ -43,6 +43,7 @@ build:
 	cd node && make build
 	cd retriever && make build
 	cd tools/traffic && make build
+	cd tools/kzgpad && make build
 
 dataapi-build:
 	cd disperser && go build -o ./bin/dataapi ./cmd/dataapi

tools/kzgpad/Makefile

@@ -0,0 +1,6 @@
+clean:
+	rm -rf ./bin
+
+build: clean
+	go mod tidy
+	go build -o ./bin/kzgpad ./cmd

tools/kzgpad/cmd/main.go

@@ -0,0 +1,76 @@
+package main
+
+import (
+	"bufio"
+	"encoding/base64"
+	"fmt"
+	"os"
+
+	"github.com/Layr-Labs/eigenda/encoding/utils/codec"
+)
+
+// Useful for converting back and forth between 4844 padded base64 representations of
+// unicode input data, for testing purposes.
+//
+// An example:
+//
+//	grpcurl \
+//		-proto ./api/proto/disperser/disperser.proto \
+//		-import-path ./api/proto \
+//		-d '{"data": "'$(tools/kzgpad/bin/kzgpad -e hello)'"}' \
+//		disperser-holesky.eigenda.xyz:443 disperser.Disperser/DisperseBlob
+//
+// Then poll for confirmation using GetBlobStatus, then retrieve blob:
+//
+//	grpcurl \
+//	  -import-path ./api/proto \
+//	  -proto ./api/proto/disperser/disperser.proto \
+//	  -d '{"batch_header_hash": "INSERT_VALUE", "blob_index":"INSERT_VALUE"}' \
+//	  disperser-holesky.eigenda.xyz:443 disperser.Disperser/RetrieveBlob | \
+//	  jq -r .data | \
+//	  tools/kzgpad/bin/kzgpad -d -
+
+func main() {
+	if len(os.Args) < 3 {
+		fmt.Fprintln(os.Stderr, "Usage: go run main.go [-e|-d] [input]")
+		os.Exit(1)
+	}
+
+	mode := os.Args[1]
+	input := os.Args[2]
+
+	if input == "-" {
+		scanner := bufio.NewScanner(os.Stdin)
+		for scanner.Scan() {
+			processInput(mode, scanner.Text())
+		}
+		if err := scanner.Err(); err != nil {
+			fmt.Fprintln(os.Stderr, "Error reading stdin:", err)
+			os.Exit(1)
+		}
+	} else {
+		processInput(mode, input)
+	}
+}
+
+func processInput(mode, text string) {
+	switch mode {
+	case "-e":
+		// Encode the input to base64
+		bz := []byte(text)
+		padded := codec.ConvertByPaddingEmptyByte(bz)
+		encoded := base64.StdEncoding.EncodeToString(padded)
+		fmt.Println(encoded)
+	case "-d":
+		// Decode the base64 input
+		decoded, err := base64.StdEncoding.DecodeString(text)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, "Error decoding base64:", err)
+			return
+		}
+		unpadded := codec.RemoveEmptyByteFromPaddedBytes(decoded)
+		fmt.Println(string(unpadded))
+	default:
+		fmt.Fprintln(os.Stderr, "Invalid mode. Use -e for encoding or -d for decoding.")
+	}
+}