Scanning Genesys Cloud Web Messaging Attachments with Go

What You Will Build

A Go service that intercepts Web Messaging file upload webhooks, downloads attachments to an isolated container directory, scans them with ClamAV over a Unix socket, quarantines threats, updates interaction attributes via the Genesys Cloud Interactions API, processes files concurrently with a worker pool, and exports scan metrics to Prometheus.
This tutorial uses the Genesys Cloud CX REST API surface.
The implementation uses Go 1.21+ with standard library networking, the Prometheus client, and raw HTTP clients for full transparency.

Prerequisites

• OAuth Client Credentials grant type registered in Genesys Cloud
• Required scopes: webmessaging:file:read, interaction:attribute:write, conversation:read
• Go 1.21 or later
• github.com/prometheus/client_golang/prometheus and github.com/prometheus/client_golang/prometheus/promhttp
• ClamAV daemon (clamd) running locally with LocalSocket /var/run/clamav/clamd.sock enabled
• Linux host or container with a read-only root filesystem and a tmpfs mount at /tmp/scanner for isolation
• golang.org/x/sync/semaphore for rate limiting concurrent downloads

Authentication Setup

Genesys Cloud uses OAuth 2.0 with the client credentials flow. The token endpoint returns a bearer token valid for approximately one hour. Your service must cache the token and refresh it before expiry to avoid interrupting webhook processing.

The following implementation uses a read-write mutex to allow concurrent reads while blocking writes during refresh. It checks the expiry timestamp and preempts refresh thirty seconds before expiration.

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"sync"
	"time"
)

type TokenCache struct {
	mu        sync.RWMutex
	token     string
	expiresAt time.Time
}

type OAuthResponse struct {
	AccessToken string `json:"access_token"`
	ExpiresIn   int    `json:"expires_in"`
	TokenType   string `json:"token_type"`
}

func (t *TokenCache) GetToken(ctx context.Context, clientID, clientSecret, baseURL string) (string, error) {
	t.mu.RLock()
	if time.Until(t.expiresAt) > 0 {
		token := t.token
		t.mu.RUnlock()
		return token, nil
	}
	t.mu.RUnlock()

	return t.refreshToken(ctx, clientID, clientSecret, baseURL)
}

func (t *TokenCache) refreshToken(ctx context.Context, clientID, clientSecret, baseURL string) (string, error) {
	t.mu.Lock()
	defer t.mu.Unlock()

	// Double-check after acquiring write lock
	if time.Until(t.expiresAt) > 0 {
		return t.token, nil
	}

	form := fmt.Sprintf("grant_type=client_credentials&scope=webmessaging%%3Afile%%3Aread+interaction%%3Aattribute%%3Awrite+conversation%%3Aread&client_id=%s&client_secret=%s",
		clientID, clientSecret)

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, fmt.Sprintf("%s/oauth/token", baseURL), nil)
	if err != nil {
		return "", fmt.Errorf("failed to create oauth request: %w", err)
	}
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	req.SetBasicAuth(clientID, clientSecret)

	client := &http.Client{Timeout: 10 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return "", fmt.Errorf("oauth request failed: %w", err)
	}
	defer resp.Body.Close()

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

	var oauthResp OAuthResponse
	if err := json.NewDecoder(resp.Body).Decode(&oauthResp); err != nil {
		return "", fmt.Errorf("failed to decode oauth response: %w", err)
	}

	t.token = oauthResp.AccessToken
	t.expiresAt = time.Now().Add(time.Duration(oauthResp.ExpiresIn-30) * time.Second)
	return t.token, nil
}

Implementation

Step 1: Webhook Handler and Binary Payload Download

Genesys Cloud posts to your registered callback URL when a Web Messaging attachment is uploaded. The payload contains a pre-signed download URL that requires a valid bearer token. You must validate the webhook signature in production, download the binary to an isolated tmpfs directory, and pass the file path to the scanning queue.

The download endpoint is GET /api/v2/webmessaging/files/{fileId}/download. The response streams the raw binary file.

type WebhookPayload struct {
	Event string `json:"event"`
	Data  struct {
		ConversationID string `json:"conversationId"`
		FileID         string `json:"fileId"`
		FileName       string `json:"fileName"`
		DownloadURL    string `json:"downloadUrl"`
	} `json:"data"`
}

func handleWebhook(w http.ResponseWriter, r *http.Request, tc *TokenCache, baseURL string, jobs chan<- ScanJob) {
	var payload WebhookPayload
	if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
		http.Error(w, "invalid payload", http.StatusBadRequest)
		return
	}

	token, err := tc.GetToken(r.Context(), os.Getenv("GENESYS_CLIENT_ID"), os.Getenv("GENESYS_CLIENT_SECRET"), baseURL)
	if err != nil {
		http.Error(w, "authentication failed", http.StatusUnauthorized)
		return
	}

	// Download binary to isolated tmpfs
	tmpDir := "/tmp/scanner"
	safeName := fmt.Sprintf("%s_%s", payload.Data.FileID, payload.Data.FileName)
	destPath := filepath.Join(tmpDir, safeName)

	out, err := os.Create(destPath)
	if err != nil {
		http.Error(w, "failed to create temp file", http.StatusInternalServerError)
		return
	}
	defer out.Close()

	req, err := http.NewRequestWithContext(r.Context(), http.MethodGet, payload.Data.DownloadURL, nil)
	if err != nil {
		http.Error(w, "failed to build download request", http.StatusInternalServerError)
		return
	}
	req.Header.Set("Authorization", "Bearer "+token)

	client := &http.Client{Timeout: 30 * time.Second}
	resp, err := client.Do(req)
	if err != nil || resp.StatusCode != http.StatusOK {
		os.Remove(destPath)
		http.Error(w, "download failed", http.StatusBadGateway)
		return
	}
	defer resp.Body.Close()

	if _, err := io.Copy(out, resp.Body); err != nil {
		os.Remove(destPath)
		http.Error(w, "failed to write file", http.StatusInternalServerError)
		return
	}

	jobs <- ScanJob{
		ConversationID: payload.Data.ConversationID,
		FileID:         payload.Data.FileID,
		FilePath:       destPath,
	}
	w.WriteHeader(http.StatusOK)
}

Step 2: ClamAV Malware Detection via Unix Socket

ClamAV exposes a binary protocol over Unix sockets. The INSTREAM command allows you to pipe file contents directly to the daemon without exposing the filesystem path, which aligns with container isolation requirements. The protocol expects carriage return-line feed (\r\n) terminators.

You must send n INSTREAM\r\n, read the PONG acknowledgment, write the file bytes, and parse the final STREAM: OK or STREAM: FOUND response.

func scanWithClamAV(filePath string) (clean bool, virusName string, err error) {
	conn, err := net.Dial("unix", "/var/run/clamav/clamd.sock")
	if err != nil {
		return false, "", fmt.Errorf("clamd socket connection failed: %w", err)
	}
	defer conn.Close()

	conn.SetDeadline(time.Now().Add(60 * time.Second))
	writer := bufio.NewWriter(conn)
	reader := bufio.NewReader(conn)

	if _, err := writer.WriteString("n INSTREAM\r\n"); err != nil {
		return false, "", fmt.Errorf("failed to send instream command: %w", err)
	}
	if err := writer.Flush(); err != nil {
		return false, "", fmt.Errorf("failed to flush command: %w", err)
	}

	pong, err := reader.ReadString('\n')
	if err != nil || pong != "PONG\r\n" {
		return false, "", fmt.Errorf("clamd did not acknowledge INSTREAM: %s", pong)
	}

	fileData, err := os.ReadFile(filePath)
	if err != nil {
		return false, "", fmt.Errorf("failed to read file: %w", err)
	}

	if _, err := writer.Write(fileData); err != nil {
		return false, "", fmt.Errorf("failed to stream file: %w", err)
	}
	if err := writer.Flush(); err != nil {
		return false, "", fmt.Errorf("failed to flush stream: %w", err)
	}

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

	result = strings.TrimSpace(result)
	if strings.HasPrefix(result, "STREAM: OK") {
		return true, "", nil
	}
	if strings.HasPrefix(result, "STREAM: FOUND") {
		parts := strings.SplitN(result, ": ", 2)
		if len(parts) == 2 {
			return false, parts[1], nil
		}
		return false, "Unknown", nil
	}
	return false, "", fmt.Errorf("unexpected clamav response: %s", result)
}

Step 3: Quarantine and Interaction Attribute Update

When ClamAV returns FOUND, you must isolate the file and record the security status on the Genesys Cloud interaction. The Interactions API allows you to patch custom attributes. You must first retrieve the existing attributes to avoid overwriting other integrations, merge the security flags, and submit the updated object.

The endpoint is PUT /api/v2/interactions/{interactionId}/attributes. Required scope: interaction:attribute:write.

type InteractionAttributes struct {
	Attributes map[string]any `json:"attributes"`
}

func updateInteractionSecurity(ctx context.Context, interactionID, token, baseURL string, virusName string) error {
	// Fetch existing attributes
	getReq, err := http.NewRequestWithContext(ctx, http.MethodGet,
		fmt.Sprintf("%s/api/v2/interactions/%s/attributes", baseURL, interactionID), nil)
	if err != nil {
		return err
	}
	getReq.Header.Set("Authorization", "Bearer "+token)

	client := &http.Client{Timeout: 15 * time.Second}
	getResp, err := client.Do(getReq)
	if err != nil {
		return fmt.Errorf("failed to fetch interaction: %w", err)
	}
	defer getResp.Body.Close()

	if getResp.StatusCode != http.StatusOK {
		return fmt.Errorf("fetch interaction failed with status %d", getResp.StatusCode)
	}

	var attrs InteractionAttributes
	if err := json.NewDecoder(getResp.Body).Decode(&attrs); err != nil {
		return fmt.Errorf("failed to decode attributes: %w", err)
	}

	if attrs.Attributes == nil {
		attrs.Attributes = make(map[string]any)
	}

	securityFlags := map[string]any{
		"malwareDetected": true,
		"virusName":       virusName,
		"detectedAt":      time.Now().UTC().Format(time.RFC3339),
		"quarantined":     true,
	}
	attrs.Attributes["security"] = securityFlags

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

	putReq, err := http.NewRequestWithContext(ctx, http.MethodPut,
		fmt.Sprintf("%s/api/v2/interactions/%s/attributes", baseURL, interactionID),
		bytes.NewReader(payload))
	if err != nil {
		return err
	}
	putReq.Header.Set("Authorization", "Bearer "+token)
	putReq.Header.Set("Content-Type", "application/json")

	putResp, err := client.Do(putReq)
	if err != nil {
		return fmt.Errorf("failed to update interaction: %w", err)
	}
	defer putResp.Body.Close()

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

Step 4: Concurrent Scanning with Worker Pools

Web Messaging traffic spikes during business hours. A worker pool prevents goroutine exhaustion and controls concurrency. Each worker reads from a buffered job channel, executes the scan, updates attributes, and increments Prometheus metrics. The pool respects a context for graceful shutdown.

type ScanJob struct {
	ConversationID string
	FileID         string
	FilePath       string
}

func worker(ctx context.Context, id int, jobs <-chan ScanJob, tc *TokenCache, baseURL string, metrics *Metrics) {
	for {
		select {
		case <-ctx.Done():
			return
		case job, ok := <-jobs:
			if !ok {
				return
			}
			processScan(ctx, job, tc, baseURL, metrics)
		}
	}
}

func processScan(ctx context.Context, job ScanJob, tc *TokenCache, baseURL string, metrics *Metrics) {
	start := time.Now()
	metrics.ScansTotal.Inc()

	clean, virusName, scanErr := scanWithClamAV(job.FilePath)
	duration := time.Since(start).Seconds()
	metrics.ScanDuration.Observe(duration)

	if scanErr != nil {
		metrics.ScanErrors.Inc()
		fmt.Printf("Worker %d: scan error for %s: %v\n", id, job.FileID, scanErr)
		return
	}

	if !clean {
		metrics.QuarantinesTotal.Inc()
		// Isolate file
		qDir := "/tmp/quarantine"
		os.MkdirAll(qDir, 0o700)
		quarantinePath := filepath.Join(qDir, filepath.Base(job.FilePath))
		if err := os.Rename(job.FilePath, quarantinePath); err != nil {
			fmt.Printf("Failed to quarantine %s: %v\n", job.FilePath, err)
		}

		token, err := tc.GetToken(ctx, os.Getenv("GENESYS_CLIENT_ID"), os.Getenv("GENESYS_CLIENT_SECRET"), baseURL)
		if err != nil {
			fmt.Printf("Token refresh failed: %v\n", err)
			return
		}

		if err := updateInteractionSecurity(ctx, job.ConversationID, token, baseURL, virusName); err != nil {
			metrics.AttributeUpdateErrors.Inc()
			fmt.Printf("Failed to update interaction %s: %v\n", job.ConversationID, err)
		} else {
			metrics.AttributeUpdatesTotal.Inc()
		}
	} else {
		// Clean files can be deleted immediately after scan
		os.Remove(job.FilePath)
	}
}

Step 5: Prometheus Metrics Integration

Exporting metrics allows your monitoring stack to trigger alerts when scan latency degrades or quarantine rates spike. You must register the metrics before starting the HTTP server and expose the /metrics endpoint.

type Metrics struct {
	ScansTotal            prometheus.Counter
	QuarantinesTotal      prometheus.Counter
	ScanErrors            prometheus.Counter
	AttributeUpdateErrors prometheus.Counter
	AttributeUpdatesTotal prometheus.Counter
	ScanDuration          prometheus.Histogram
}

func NewMetrics() *Metrics {
	m := &Metrics{}
	m.ScansTotal = prometheus.NewCounter(prometheus.CounterOpts{
		Name: "genesys_attachment_scans_total",
		Help: "Total number of attachment scans initiated.",
	})
	m.QuarantinesTotal = prometheus.NewCounter(prometheus.CounterOpts{
		Name: "genesys_attachment_quarantines_total",
		Help: "Total number of attachments quarantined due to malware.",
	})
	m.ScanErrors = prometheus.NewCounter(prometheus.CounterOpts{
		Name: "genesys_attachment_scan_errors_total",
		Help: "Total number of failed ClamAV scans.",
	})
	m.AttributeUpdateErrors = prometheus.NewCounter(prometheus.CounterOpts{
		Name: "genesys_attribute_update_errors_total",
		Help: "Total number of failed interaction attribute updates.",
	})
	m.AttributeUpdatesTotal = prometheus.NewCounter(prometheus.CounterOpts{
		Name: "genesys_attribute_updates_total",
		Help: "Total number of successful interaction attribute updates.",
	})
	m.ScanDuration = prometheus.NewHistogram(prometheus.HistogramOpts{
		Name:    "genesys_attachment_scan_duration_seconds",
		Help:    "Time spent scanning attachments with ClamAV.",
		Buckets: prometheus.ExponentialBuckets(0.01, 2, 10),
	})

	prometheus.MustRegister(m.ScansTotal, m.QuarantinesTotal, m.ScanErrors,
		m.AttributeUpdateErrors, m.AttributeUpdatesTotal, m.ScanDuration)
	return m
}

Complete Working Example

The following script combines authentication, webhook handling, ClamAV scanning, interaction updates, worker pooling, and metrics export into a single production-ready service. Set the environment variables GENESYS_CLIENT_ID, GENESYS_CLIENT_SECRET, and GENESYS_BASE_URL before execution.

package main

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net"
	"net/http"
	"os"
	"os/signal"
	"path/filepath"
	"strings"
	"sync"
	"syscall"
	"time"

	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"
)

// [TokenCache, OAuthResponse, WebhookPayload, ScanJob, Metrics, InteractionAttributes structs omitted for brevity - include from previous sections]
// [GetToken, refreshToken, handleWebhook, scanWithClamAV, updateInteractionSecurity, worker, processScan, NewMetrics functions omitted - include from previous sections]

func main() {
	ctx, cancel := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer cancel()

	baseURL := os.Getenv("GENESYS_BASE_URL")
	if baseURL == "" {
		baseURL = "https://api.mypurecloud.com"
	}

	tc := &TokenCache{}
	metrics := NewMetrics()
	jobs := make(chan ScanJob, 100)

	// Start worker pool
	numWorkers := 10
	var wg sync.WaitGroup
	for i := 0; i < numWorkers; i++ {
		wg.Add(1)
		go func(wid int) {
			defer wg.Done()
			worker(ctx, wid, jobs, tc, baseURL, metrics)
		}(i)
	}

	// HTTP Server
	mux := http.NewServeMux()
	mux.HandleFunc("/webhook", func(w http.ResponseWriter, r *http.Request) {
		handleWebhook(w, r, tc, baseURL, jobs)
	})
	mux.Handle("/metrics", promhttp.Handler())

	srv := &http.Server{
		Addr:    ":8080",
		Handler: mux,
	}

	go func() {
		fmt.Println("Scanner listening on :8080")
		if err := srv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			fmt.Printf("HTTP server failed: %v\n", err)
			cancel()
		}
	}()

	<-ctx.Done()
	fmt.Println("Shutting down...")

	shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), 15*time.Second)
	defer shutdownCancel()

	close(jobs)
	wg.Wait()
	srv.Shutdown(shutdownCtx)
	fmt.Println("Graceful shutdown complete.")
}

Common Errors and Debugging

Error: 401 Unauthorized or 403 Forbidden

This occurs when the OAuth token has expired or lacks the required scopes. The TokenCache implementation preempts refresh thirty seconds before expiry. If you still receive 401 responses, verify that your OAuth client in the Genesys Cloud admin console includes webmessaging:file:read and interaction:attribute:write. Check the token endpoint response for expires_in values that differ from expected durations.

Error: 429 Too Many Requests

Genesys Cloud enforces rate limits per client ID. The Interactions API limits attribute updates to a finite number per minute. Implement exponential backoff when you receive a 429 status. Parse the Retry-After header if present, otherwise wait between 1 and 5 seconds before retrying.

func retryWithBackoff(ctx context.Context, operation func() error) error {
	attempts := 0
	for {
		err := operation()
		if err == nil {
			return nil
		}
		attempts++
		if attempts > 3 {
			return err
		}
		backoff := time.Duration(1<<uint(attempts-1)) * time.Second
		select {
		case <-ctx.Done():
			return ctx.Err()
		case <-time.After(backoff):
			continue
		}
	}
}

Error: ClamAV Socket Connection Refused

The daemon may not be running, or the socket path differs from your configuration. Verify the socket location with clamd -c /etc/clamd.d/clamd.conf | grep LocalSocket. Ensure the container has CAP_NET_ADMIN or runs as a user with read-write access to the socket directory. The INSTREAM command requires the daemon to accept network/stream connections; verify TCPSocket or LocalSocket is enabled in clamd.conf.

Error: 400 Bad Request on Interaction Attribute Update

The Interactions API rejects malformed JSON or attribute keys that exceed length limits. Attribute keys must be alphanumeric with underscores, limited to 255 characters. Ensure the security object is nested correctly under attributes. Validate your payload against the schema before submission.

Official References

• Web Messaging File Upload API
• Interactions Attribute API
• OAuth 2.0 Client Credentials Flow
• ClamAV INSTREAM Protocol Documentation
• Prometheus Go Client