Issues retrieving binary data?

[jlcd]

I tried using the out of the box API, with no tweaks, to download an image and a pdf.

None returned a valid resource: both the PDF and PNG were "corrupted" after delivery.

Was able to download it but had to make an alternative tls_client_cffi_src.BuildResponse()

I can dig deeper later, but just wanted to leave the question here in case anyone knowns more.

[bogdanfinn]

@jlcd We have in the tls-client repo in the shared library an example how to download or upload images using the shared library api: https://github.com/bogdanfinn/tls-client/blob/master/cffi_dist/example_node/index_image.js

You can use the same payload with the standalone api.

Please note the isByteResponse Field, which you need to set to true. Check the linked example code.

[jlcd]

That makes sense, but mandates that we know what to expect from a request.

I came up with a different approach for the API:

New response-builder.go:

package api

import (
	"encoding/base64"
	"io"
	"mime"
	"strings"

	http "github.com/bogdanfinn/fhttp"
	tls_client_cffi_src "github.com/bogdanfinn/tls-client/cffi_src"
	"github.com/google/uuid"
)

// CustomResponse extends the original Response with binary data handling
type CustomResponse struct {
	Id                string                       `json:"id"`
	SessionId         string                       `json:"sessionId,omitempty"`
	Status            int                          `json:"status"`
	Target            string                       `json:"target"`
	Body              string                       `json:"body"`
	Headers           map[string][]string          `json:"headers"`
	Cookies           []tls_client_cffi_src.Cookie `json:"cookies"`
	EncodedBinaryData bool                         `json:"encodedBinaryData"`
}

// BuildCustomResponse creates a response with proper binary data handling
func BuildCustomResponse(sessionId string, withSession bool, resp *http.Response, sessionCookies []*http.Cookie, input tls_client_cffi_src.RequestInput) (*CustomResponse, error) {
	// Read the response body
	bodyBytes, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	// Determine if this is binary content
	contentType := resp.Header.Get("Content-Type")
	isBinary := isBinaryContent(contentType, bodyBytes)

	// Handle body encoding
	var bodyString string
	var encodedBinaryData bool

	if isBinary {
		// Base64 encode binary data
		bodyString = base64.StdEncoding.EncodeToString(bodyBytes)
		encodedBinaryData = true
	} else {
		// Keep text data as string
		bodyString = string(bodyBytes)
		encodedBinaryData = false
	}

	// Convert headers
	headers := make(map[string][]string)
	for key, values := range resp.Header {
		headers[key] = values
	}

	// Convert cookies
	cookies := transformCookies(sessionCookies)

	// Build response
	response := &CustomResponse{
		Id:                uuid.New().String(),
		Status:            resp.StatusCode,
		Target:            resp.Request.URL.String(),
		Body:              bodyString,
		Headers:           headers,
		Cookies:           cookies,
		EncodedBinaryData: encodedBinaryData,
	}

	if withSession {
		response.SessionId = sessionId
	}

	return response, nil
}

// isBinaryContent determines if the content is binary based on Content-Type
func isBinaryContent(contentType string, data []byte) bool {
	// Parse the media type
	mediaType, _, err := mime.ParseMediaType(contentType)
	if err != nil {
		// If we can't parse, fall back to content analysis
		return isBinaryData(data)
	}

	// Check for known binary types
	binaryTypes := map[string]bool{
		"image/jpeg":               true,
		"image/jpg":                true,
		"image/png":                true,
		"image/gif":                true,
		"image/webp":               true,
		"image/avif":               true,
		"image/bmp":                true,
		"image/tiff":               true,
		"application/pdf":          true,
		"application/zip":          true,
		"application/octet-stream": true,
		"video/mp4":                true,
		"audio/mpeg":               true,
	}

	// Check if it's a known binary type
	if isBinary, exists := binaryTypes[mediaType]; exists {
		return isBinary
	}

	// Check for text-based types
	if strings.HasPrefix(mediaType, "text/") ||
		mediaType == "application/json" ||
		mediaType == "application/xml" ||
		mediaType == "application/javascript" ||
		strings.HasSuffix(mediaType, "+json") ||
		strings.HasSuffix(mediaType, "+xml") {
		return false
	}

	// Fall back to content analysis for unknown types
	return isBinaryData(data)
}

// isBinaryData performs heuristic analysis to determine if data is binary
func isBinaryData(data []byte) bool {
	// Empty data is not binary
	if len(data) == 0 {
		return false
	}

	// Check first 512 bytes (or less if data is smaller)
	sampleSize := 512
	if len(data) < sampleSize {
		sampleSize = len(data)
	}

	sample := data[:sampleSize]

	// Count null bytes
	nullBytes := 0
	for _, b := range sample {
		if b == 0 {
			nullBytes++
		}
	}

	// If more than 1% null bytes, likely binary
	return float64(nullBytes)/float64(sampleSize) > 0.01
}

and in tls-client-api/api/forward-request-handler.go I did:

-	response, err := tls_client_cffi_src.BuildResponse(sessionId, withSession, resp, sessionCookies, *input)
-
-	if err != nil {
-		return handleErrorResponse(fh.logger, sessionId, withSession, err)
-	}
-
-	return apiserver.NewJsonResponse(response), nil
+	customResponse, buildErr := BuildCustomResponse(sessionId, withSession, resp, sessionCookies, *input)
+
+	if buildErr != nil {
+		clientErr := tls_client_cffi_src.NewTLSClientError(buildErr)
+		return handleErrorResponse(fh.logger, sessionId, withSession, clientErr)
+	}
+
+	return apiserver.NewJsonResponse(customResponse), nil

It basically auto-detects binary data and encodes it, and the client has to decode, by reading the new property EncodedBinaryData (boolean).