50 lines
1.1 KiB
Go
50 lines
1.1 KiB
Go
package tracking
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import (
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"crypto/sha256"
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"encoding/hex"
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"errors"
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"fmt"
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"time"
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)
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// GeneratePixelURL creates a tracking pixel URL for an email
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func GeneratePixelURL(cfg *Config, recipient, subject string) (string, string, error) {
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if !cfg.IsConfigured() {
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return "", "", errTrackingNotConfigured
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}
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// Hash subject (first 6 chars)
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subjectHash := hashSubject(subject)
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payload := &PixelPayload{
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Recipient: recipient,
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SubjectHash: subjectHash,
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SentAt: time.Now().Unix(),
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}
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blob, err := Encrypt(payload, cfg.TrackingKey)
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if err != nil {
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return "", "", fmt.Errorf("encrypt payload: %w", err)
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}
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pixelURL := fmt.Sprintf("%s/p/%s.gif", cfg.WorkerURL, blob)
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return pixelURL, blob, nil
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}
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// GeneratePixelHTML returns HTML img tag for the tracking pixel
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func GeneratePixelHTML(pixelURL string) string {
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return fmt.Sprintf(
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`<img src="%s" width="1" height="1" style="display:none;width:1px;height:1px;border:0;" alt="" />`,
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pixelURL,
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)
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}
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func hashSubject(subject string) string {
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h := sha256.Sum256([]byte(subject))
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return hex.EncodeToString(h[:])[:6]
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}
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var errTrackingNotConfigured = errors.New("tracking not configured")
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