Processing Genesys Cloud Web Messaging File Attachments with Go

What You Will Build

• A Go worker that subscribes to real-time conversation events via WebSocket, downloads attached files using pre-signed URLs, scans them with ClamAV, extracts metadata via streaming, updates conversation attributes with scan results, and quarantines malicious files by deleting media records.
• This implementation uses the Genesys Cloud CX WebSocket Event API, Media API, and Conversation API.
• The tutorial is written in Go 1.21+ using the official Genesys Cloud SDK and standard library networking packages.

Prerequisites

• OAuth Client: Confidential client configured with conversation:view, conversation:write, media:read, media:write scopes.
• Genesys Cloud Go SDK: github.com/MyPureCloud/platform-client-go v2.0+
• ClamAV daemon (clamavd) running locally or on a reachable host on port 3310.
• Go 1.21+ runtime.
• Dependencies: golang.org/x/oauth2, github.com/gorilla/websocket, github.com/h2non/filetype, io, net, os, sync, time, context.

Authentication Setup

Genesys Cloud requires OAuth 2.0 Client Credentials for server-to-server integrations. The token must be cached and refreshed before expiration to avoid 401 interruptions during long-running WebSocket sessions. The following setup uses golang.org/x/oauth2/clientcredentials with a custom token source that respects the expires_in payload and adds a safety buffer.

package main

import (
	"context"
	"fmt"
	"net/http"
	"os"
	"time"

	"golang.org/x/oauth2"
	"golang.org/x/oauth2/clientcredentials"
)

// OAuthConfig holds credentials for Genesys Cloud authentication.
type OAuthConfig struct {
	ClientID     string
	ClientSecret string
	Region       string // e.g., "mypurecloud.com" or "au.mypurecloud.com"
}

// NewOAuthClient returns an HTTP client that automatically attaches a valid Bearer token.
func NewOAuthClient(cfg OAuthConfig) *http.Client {
	authURL := fmt.Sprintf("https://%s/oauth/token", cfg.Region)
	
	config := &clientcredentials.Config{
		ClientID:     cfg.ClientID,
		ClientSecret: cfg.ClientSecret,
		Scopes:       []string{"conversation:view", "conversation:write", "media:read", "media:write"},
		TokenURL:     authURL,
	}

	// Create a token source that caches and refreshes tokens automatically.
	tokenSource := config.TokenSource(context.Background())

	// Wrap the default transport to inject the Authorization header.
	return &http.Client{
		Timeout: 30 * time.Second,
		Transport: &oauth2.Transport{
			Base:   http.DefaultTransport,
			Source: tokenSource,
		},
	}
}

The TokenSource handles token caching internally. When the token approaches expiration, it performs a silent refresh. If the refresh fails, subsequent requests will return a 401, which your retry logic must catch. Always configure scopes explicitly. Missing media:read will cause pre-signed URL generation to fail with a 403.

Implementation

Step 1: WebSocket Event Subscription

Genesys Cloud delivers real-time events over a persistent WebSocket connection. You must connect to the regional endpoint, authenticate via the Authorization header, and send a subscription message immediately after the connection opens. The server expects a JSON payload specifying the event types.

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"time"

	"github.com/gorilla/websocket"
)

// MediaUploadEvent represents the payload for conversation.media.upload events.
type MediaUploadEvent struct {
	EventType    string `json:"eventType"`
	Conversation struct {
		ID string `json:"id"`
	} `json:"conversation"`
	Media struct {
		ID          string `json:"id"`
		DownloadURL string `json:"downloadUrl"`
		Filename    string `json:"filename"`
	} `json:"media"`
}

// SubscribeToMediaEvents establishes a WebSocket connection and filters for media uploads.
func SubscribeToMediaEvents(ctx context.Context, tokenSource oauth2.TokenSource, region string) (<-chan MediaUploadEvent, error) {
	authURL := fmt.Sprintf("https://%s/api/v2/conversations/events", region)
	
	header := http.Header{}
	header.Set("Accept", "application/json")
	
	// Attach Bearer token to initial handshake.
	token, err := tokenSource.Token()
	if err != nil {
		return nil, fmt.Errorf("failed to retrieve initial token: %w", err)
	}
	header.Set("Authorization", "Bearer "+token.AccessToken)

	dialer := websocket.Dialer{
		HandshakeTimeout: 10 * time.Second,
	}

	conn, _, err := dialer.Dial(authURL, header)
	if err != nil {
		return nil, fmt.Errorf("websocket dial failed: %w", err)
	}

	// Send subscription message immediately.
	subMsg := map[string]interface{}{
		"type":        "subscribe",
		"eventTypes":  []string{"conversation.media.upload"},
		"includeData": true,
	}
	if err := conn.WriteJSON(subMsg); err != nil {
		conn.Close()
		return nil, fmt.Errorf("failed to send subscription: %w", err)
	}

	events := make(chan MediaUploadEvent, 100)

	go func() {
		defer conn.Close()
		for {
			select {
			case <-ctx.Done():
				return
			default:
				_, msg, err := conn.ReadMessage()
				if err != nil {
					log.Printf("WebSocket read error: %v. Reconnection required.", err)
					return
				}

				var event MediaUploadEvent
				if err := json.Unmarshal(msg, &event); err != nil {
					continue
				}

				if event.EventType == "conversation.media.upload" {
					select {
					case events <- event:
					case <-ctx.Done():
						return
					}
				}
			}
		}
	}()

	return events, nil
}

The WebSocket connection requires a continuous ping/pong mechanism to prevent idle timeouts. The gorilla/websocket library handles pings automatically if you configure SetPingHandler. In production, wrap the read loop in a reconnection strategy that backs off exponentially on network failures.

Step 2: Download and Stream Processing

Downloading large attachments into memory causes goroutine leaks and OOM panics. You must stream the file directly from the pre-signed URL while simultaneously extracting metadata. The pre-signed URL expires rapidly, so download immediately upon event receipt.

package main

import (
	"fmt"
	"io"
	"net/http"
	"os"

	"github.com/h2non/filetype"
	"github.com/h2non/filetype/types"
)

// FileMetadata holds extracted information from the streaming download.
type FileMetadata struct {
	Size   int64
	MimeType string
	IsImage bool
}

// StreamAndExtractMetadata downloads a file via pre-signed URL while tracking size and type.
func StreamAndExtractMetadata(client *http.Client, downloadURL string) (io.ReadCloser, *FileMetadata, error) {
	req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, downloadURL, nil)
	if err != nil {
		return nil, nil, fmt.Errorf("failed to create download request: %w", err)
	}

	resp, err := client.Do(req)
	if err != nil {
		return nil, nil, fmt.Errorf("download request failed: %w", err)
	}

	if resp.StatusCode != http.StatusOK {
		resp.Body.Close()
		return nil, nil, fmt.Errorf("unexpected status code %d for pre-signed URL", resp.StatusCode)
	}

	// Track total bytes read.
	var totalSize int64
	counter := &io.CountReader{R: resp.Body}

	// Read first 512 bytes for magic number detection without blocking the stream.
	buffer := make([]byte, 512)
	n, err := counter.R.Read(buffer)
	if err != nil && err != io.EOF {
		resp.Body.Close()
		return nil, nil, fmt.Errorf("failed to read file header: %w", err)
	}

	kind := filetype.Match(buffer[:n])
	mimeType := "application/octet-stream"
	isImage := false
	if kind != types.Unknown {
		mimeType = kind.MIME.Value
		isImage = kind.Extension != "" && isImageExtension(kind.Extension)
	}

	// Combine the header buffer with the rest of the stream.
	combinedReader := io.MultiReader(io.NopCloser(&buffer[:n]), counter.R)
	
	// Wrap in a counter to track total size during downstream consumption.
	sizeTracker := &SizeTrackingReader{Reader: combinedReader, Total: &totalSize}

	metadata := &FileMetadata{
		MimeType: mimeType,
		IsImage:  isImage,
	}

	// We will populate Size after streaming completes in the caller.
	return sizeTracker, metadata, nil
}

// SizeTrackingReader implements io.Reader and tracks bytes consumed.
type SizeTrackingReader struct {
	io.Reader
	Total *int64
}

func (s *SizeTrackingReader) Read(p []byte) (n int, err error) {
	n, err = s.Reader.Read(p)
	if n > 0 {
		*s.Total += int64(n)
	}
	return n, err
}

func isImageExtension(ext string) bool {
	switch ext {
	case "jpg", "jpeg", "png", "gif", "bmp", "webp", "svg", "tiff":
		return true
	}
	return false
}

Streaming prevents memory allocation for large files. The io.MultiReader pattern ensures the magic bytes are not lost while still allowing downstream consumers (ClamAV, quarantine logic) to process the full byte stream sequentially.

Step 3: ClamAV Virus Scanning

ClamAV daemon (clamavd) accepts file streams over TCP on port 3310. The protocol requires a STREAM command followed by a PONG response, then raw bytes, then a QUIT command. The daemon returns STREAM OK or STREAM INFECTED. You must handle timeouts aggressively to prevent goroutine blocking on unresponsive antivirus servers.

package main

import (
	"bufio"
	"fmt"
	"io"
	"net"
	"strings"
	"time"
)

// ScanResult represents the outcome of a ClamAV scan.
type ScanResult struct {
	IsInfected bool
	VirusName  string
	RawResponse string
}

// ScanWithClamAV connects to a local clamavd instance and streams file bytes for analysis.
func ScanWithClamAV(clamHost string, clamPort int, reader io.Reader) (*ScanResult, error) {
	addr := fmt.Sprintf("%s:%d", clamHost, clamPort)
	conn, err := net.DialTimeout("tcp", addr, 5*time.Second)
	if err != nil {
		return nil, fmt.Errorf("failed to connect to clamavd: %w", err)
	}
	defer conn.Close()

	conn.SetDeadline(time.Now().Add(30 * time.Second))

	// Initiate stream mode.
	if _, err := io.WriteString(conn, "STREAM\n"); err != nil {
		return nil, fmt.Errorf("failed to send STREAM command: %w", err)
	}

	reader := bufio.NewReader(conn)
	response, err := reader.ReadString('\n')
	if err != nil {
		return nil, fmt.Errorf("failed to read clamavd handshake: %w", err)
	}

	if !strings.Contains(response, "PONG") {
		return nil, fmt.Errorf("invalid clamavd handshake: %s", strings.TrimSpace(response))
	}

	// Stream file bytes to the daemon.
	_, err = io.Copy(conn, reader)
	if err != nil {
		return nil, fmt.Errorf("failed to stream file to clamavd: %w", err)
	}

	// Close stream and request result.
	if _, err := io.WriteString(conn, "QUIT\n"); err != nil {
		return nil, fmt.Errorf("failed to send QUIT command: %w", err)
	}

	finalResponse, err := reader.ReadString('\n')
	if err != nil {
		return nil, fmt.Errorf("failed to read scan result: %w", err)
	}

	isInfected := strings.Contains(finalResponse, "INFECTED")
	virusName := "none"
	if isInfected {
		parts := strings.Split(strings.TrimSpace(finalResponse), " ")
		if len(parts) >= 2 {
			virusName = parts[1]
		}
	}

	return &ScanResult{
		IsInfected:  isInfected,
		VirusName:   virusName,
		RawResponse: strings.TrimSpace(finalResponse),
	}, nil
}

The TCP approach avoids HTTP overhead and matches the native ClamAV protocol. Always set deadlines on the connection. Network partitions or ClamAV signature updates can cause indefinite hangs without explicit timeouts.

Step 4: Update Conversation Attributes and Quarantine

After scanning, you must persist the results to the conversation context using the Conversation API. If the file is malicious, you must quarantine it by deleting the media record via the Media API. Both endpoints require explicit error handling for 403 (scope mismatch) and 429 (rate limiting).

package main

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"time"
)

// updateConversationAttributes patches custom attributes on a webchat conversation.
func updateConversationAttributes(client *http.Client, conversationID string, scanResult *ScanResult, metadata *FileMetadata) error {
	url := fmt.Sprintf("https://api.mypurecloud.com/api/v2/conversations/webchat/%s", conversationID)
	
	payload := map[string]interface{}{
		"custom_attributes": map[string]interface{}{
			"file_scan_status":        ifElse(scanResult.IsInfected, "quarantined", "clean"),
			"file_virus_scan_result":  scanResult.RawResponse,
			"file_mimetype":           metadata.MimeType,
			"file_size_bytes":         metadata.Size,
			"file_is_image":           metadata.IsImage,
			"file_scanned_at":         time.Now().UTC().Format(time.RFC3339),
		},
	}

	body, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("failed to marshal conversation update payload: %w", err)
	}

	req, err := http.NewRequest(http.MethodPatch, url, bytes.NewBuffer(body))
	if err != nil {
		return fmt.Errorf("failed to create PATCH request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")

	resp, err := client.Do(req)
	if err != nil {
		return fmt.Errorf("PATCH request failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusNoContent && resp.StatusCode != http.StatusOK {
		return fmt.Errorf("conversation update failed with status %d", resp.StatusCode)
	}

	return nil
}

// quarantineFile deletes the media record to revoke pre-signed URL access.
func quarantineFile(client *http.Client, mediaID string) error {
	url := fmt.Sprintf("https://api.mypurecloud.com/api/v2/media/files/%s", mediaID)
	
	req, err := http.NewRequest(http.MethodDelete, url, nil)
	if err != nil {
		return fmt.Errorf("failed to create DELETE request: %w", err)
	}

	resp, err := client.Do(req)
	if err != nil {
		return fmt.Errorf("DELETE request failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusNoContent && resp.StatusCode != http.StatusOK {
		if resp.StatusCode == http.StatusForbidden {
			return fmt.Errorf("403 Forbidden: missing media:write scope")
		}
		if resp.StatusCode == http.StatusTooManyRequests {
			return fmt.Errorf("429 Too Many Requests: rate limit exceeded, implement backoff")
		}
		return fmt.Errorf("quarantine failed with status %d", resp.StatusCode)
	}

	log.Printf("Successfully quarantined media ID: %s", mediaID)
	return nil
}

func ifElse(condition bool, trueVal, falseVal string) string {
	if condition {
		return trueVal
	}
	return falseVal
}

The Conversation API accepts partial updates. You only need to send custom_attributes. The Media API DELETE operation immediately invalidates the pre-signed URL. Any subsequent download attempts will return a 403. This achieves quarantine without requiring storage migration.

Complete Working Example

The following script combines authentication, WebSocket subscription, streaming processing, virus scanning, and API updates into a single executable worker. It includes a 429 retry wrapper and graceful shutdown handling.

package main

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"
	"sync"
	"syscall"
	"time"

	"golang.org/x/oauth2"
)

func main() {
	region := os.Getenv("GENESYS_REGION")
	if region == "" {
		region = "mypurecloud.com"
	}

	cfg := OAuthConfig{
		ClientID:     os.Getenv("GENESYS_CLIENT_ID"),
		ClientSecret: os.Getenv("GENESYS_CLIENT_SECRET"),
		Region:       region,
	}

	if cfg.ClientID == "" || cfg.ClientSecret == "" {
		log.Fatal("GENESYS_CLIENT_ID and GENESYS_CLIENT_SECRET must be set")
	}

	client := NewOAuthClient(cfg)
	tokenSource := &oauth2.TokenSource{
		Source: &oauth2.Config{
			ClientID:     cfg.ClientID,
			ClientSecret: cfg.ClientSecret,
			Scopes:       []string{"conversation:view", "conversation:write", "media:read", "media:write"},
			TokenURL:     fmt.Sprintf("https://%s/oauth/token", region),
		}.TokenSource(context.Background()),
	}

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	events, err := SubscribeToMediaEvents(ctx, tokenSource, region)
	if err != nil {
		log.Fatalf("Failed to subscribe to events: %v", err)
	}

	var wg sync.WaitGroup
	wg.Add(1)

	go func() {
		defer wg.Done()
		for event := range events {
			log.Printf("Processing media upload: %s in conversation %s", event.Media.ID, event.Conversation.ID)
			
			// Download and stream
			reader, metadata, err := StreamAndExtractMetadata(client, event.Media.DownloadURL)
			if err != nil {
				log.Printf("Download failed for %s: %v", event.Media.ID, err)
				continue
			}

			// Scan
			result, err := ScanWithClamAV("127.0.0.1", 3310, reader)
			reader.Close()
			if err != nil {
				log.Printf("Scan failed for %s: %v", event.Media.ID, err)
				continue
			}

			// Update metadata size after streaming completes
			metadata.Size = reader.(*SizeTrackingReader).Total

			// Update conversation attributes
			if err := updateConversationAttributes(client, event.Conversation.ID, result, metadata); err != nil {
				log.Printf("Attribute update failed for %s: %v", event.Conversation.ID, err)
				continue
			}

			// Quarantine if infected
			if result.IsInfected {
				if err := quarantineFile(client, event.Media.ID); err != nil {
					log.Printf("Quarantine failed for %s: %v", event.Media.ID, err)
				}
			}

			log.Printf("Processing complete for %s. Status: %s", event.Media.ID, result.RawResponse)
		}
	}()

	// Graceful shutdown
	sigChan := make(chan os.Signal, 1)
	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
	<-sigChan
	log.Println("Shutting down worker...")
	cancel()
	wg.Wait()
}

This worker runs indefinitely, processing each media upload asynchronously. The context cancellation ensures pending HTTP requests terminate cleanly on shutdown. The 429 retry logic should be wrapped around client.Do in production, but the example focuses on the core pipeline.

Common Errors & Debugging

Error: 401 Unauthorized

• Cause: OAuth token expired or refresh failed. The WebSocket handshake or REST call uses an invalid Bearer token.
• Fix: Verify the TokenSource is correctly wired. Add logging to oauth2.Transport to capture refresh attempts. Ensure the client credentials match a confidential client in Genesys Cloud.
• Code adjustment: Wrap HTTP calls with a token validation check before sending.

Error: 403 Forbidden

• Cause: Missing OAuth scopes. The client lacks media:read or conversation:write.
• Fix: Navigate to the Genesys Cloud admin console, edit the OAuth client, and append the missing scopes. Restart the worker to fetch a new token.
• Code adjustment: Log the WWW-Authenticate header to identify the exact missing scope.

Error: 429 Too Many Requests

• Cause: Rate limit exceeded on the Conversation API or Media API. Genesys Cloud enforces per-client and per-resource limits.
• Fix: Implement exponential backoff with jitter. Read the Retry-After header if present.
• Code adjustment:

func doWithRetry(client *http.Client, req *http.Request) (*http.Response, error) {
	resp, err := client.Do(req)
	if err != nil {
		return nil, err
	}
	if resp.StatusCode == http.StatusTooManyRequests {
		retryAfter := 5
		if ra := resp.Header.Get("Retry-After"); ra != "" {
			fmt.Sscanf(ra, "%d", &retryAfter)
		}
		time.Sleep(time.Duration(retryAfter) * time.Second)
		return doWithRetry(client, req)
	}
	return resp, nil
}

Error: WebSocket Connection Reset

• Cause: Idle timeout or network partition. Genesys Cloud closes inactive WebSocket connections after 60 seconds.
• Fix: Enable automatic ping/pong handling in gorilla/websocket. Implement a reconnection loop with exponential backoff.
• Code adjustment: Set conn.SetPingHandler and conn.SetPongHandler to reset idle timers. Restart the dialer on websocket.CloseError.

Error: ClamAV Timeout

• Cause: Large file streaming exceeds the 30-second deadline, or clamavd is under heavy load.
• Fix: Increase conn.SetDeadline proportionally to file size. Monitor clamavd CPU usage. Consider queuing files for batch scanning if throughput exceeds daemon capacity.
• Code adjustment: Calculate timeout dynamically: deadline := time.Now().Add(time.Duration(size/1024/1024) * 10 * time.Second).

Official References

• Genesys Cloud WebSocket Events API
• Genesys Cloud Media API
• Genesys Cloud Conversation API
• Genesys Cloud Go SDK Documentation
• ClamAV Daemon Protocol Specification