1 files changed, 319 insertions, 0 deletions
diff --git a/transport/mesh/storeforward.go b/transport/mesh/storeforward.go
new file mode 100644
index 0000000..1fcb93d
--- /dev/null
+++ b/transport/mesh/storeforward.go
@@ -0,0 +1,319 @@
+// Package mesh - Store-and-forward messaging for offline scenarios
+package mesh
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+)
+
+// MessageQueue implements store-and-forward messaging
+// Critical for military scenarios where connectivity is intermittent
+type MessageQueue struct {
+	pending      map[string][]*QueuedMessage // recipient -> messages
+	delivered    map[string]bool             // message ID -> delivered
+	queueDir     string                      // Persistent storage directory
+	maxAge       time.Duration               // Auto-delete after this time
+	maxSize      int                         // Max messages in queue
+	encrypted    bool                        // Encrypt queue on disk
+	mu           sync.RWMutex
+	onDelivered  func(string)                // Callback when message delivered
+}
+
+// QueuedMessage represents a message waiting for delivery
+type QueuedMessage struct {
+	ID          string    `json:"id"`           // Unique message ID
+	From        string    `json:"from"`         // Sender public key
+	To          string    `json:"to"`           // Recipient public key
+	Content     []byte    `json:"content"`      // Encrypted message content
+	Timestamp   time.Time `json:"timestamp"`    // When queued
+	Attempts    int       `json:"attempts"`     // Delivery attempts
+	MaxAttempts int       `json:"max_attempts"` // Give up after this many
+	Priority    int       `json:"priority"`     // Higher = more important
+	Hops        int       `json:"hops"`         // How many hops so far
+	MaxHops     int       `json:"max_hops"`     // Don't forward beyond this
+}
+
+// QueueConfig holds message queue configuration
+type QueueConfig struct {
+	QueueDir    string        // Where to store pending messages
+	MaxAge      time.Duration // Auto-delete messages older than this
+	MaxSize     int           // Max messages per recipient
+	MaxAttempts int           // Max delivery attempts
+	MaxHops     int           // Max forwarding hops
+	Encrypted   bool          // Encrypt queue on disk
+}
+
+// NewMessageQueue creates a new message queue
+func NewMessageQueue(config *QueueConfig) (*MessageQueue, error) {
+	if config == nil {
+		config = &QueueConfig{
+			QueueDir:    filepath.Join(os.TempDir(), "veilith-queue"),
+			MaxAge:      24 * time.Hour,
+			MaxSize:     1000,
+			MaxAttempts: 10,
+			MaxHops:     5,
+			Encrypted:   true,
+		}
+	}
+
+	// Create queue directory
+	if err := os.MkdirAll(config.QueueDir, 0700); err != nil {
+		return nil, fmt.Errorf("failed to create queue dir: %w", err)
+	}
+
+	mq := &MessageQueue{
+		pending:   make(map[string][]*QueuedMessage),
+		delivered: make(map[string]bool),
+		queueDir:  config.QueueDir,
+		maxAge:    config.MaxAge,
+		maxSize:   config.MaxSize,
+		encrypted: config.Encrypted,
+	}
+
+	// Load existing queue from disk
+	if err := mq.loadFromDisk(); err != nil {
+		return nil, fmt.Errorf("failed to load queue: %w", err)
+	}
+
+	// Start background cleanup
+	go mq.cleanupLoop()
+
+	return mq, nil
+}
+
+// Enqueue adds a message to the queue
+func (mq *MessageQueue) Enqueue(msg *QueuedMessage) error {
+	mq.mu.Lock()
+	defer mq.mu.Unlock()
+
+	// Check if already delivered
+	if mq.delivered[msg.ID] {
+		return fmt.Errorf("message already delivered")
+	}
+
+	// Check queue size limit
+	if len(mq.pending[msg.To]) >= mq.maxSize {
+		return fmt.Errorf("queue full for recipient %s", msg.To)
+	}
+
+	// Add to pending queue
+	mq.pending[msg.To] = append(mq.pending[msg.To], msg)
+
+	// Persist to disk
+	if err := mq.saveToDisk(); err != nil {
+		return fmt.Errorf("failed to save queue: %w", err)
+	}
+
+	return nil
+}
+
+// Dequeue retrieves messages for a specific recipient
+func (mq *MessageQueue) Dequeue(recipient string) []*QueuedMessage {
+	mq.mu.Lock()
+	defer mq.mu.Unlock()
+
+	messages := mq.pending[recipient]
+	delete(mq.pending, recipient)
+
+	// Mark as delivered
+	for _, msg := range messages {
+		mq.delivered[msg.ID] = true
+		if mq.onDelivered != nil {
+			go mq.onDelivered(msg.ID)
+		}
+	}
+
+	// Persist to disk
+	mq.saveToDisk()
+
+	return messages
+}
+
+// GetPendingCount returns number of pending messages for a recipient
+func (mq *MessageQueue) GetPendingCount(recipient string) int {
+	mq.mu.RLock()
+	defer mq.mu.RUnlock()
+	return len(mq.pending[recipient])
+}
+
+// GetTotalPendingCount returns total number of pending messages
+func (mq *MessageQueue) GetTotalPendingCount() int {
+	mq.mu.RLock()
+	defer mq.mu.RUnlock()
+
+	total := 0
+	for _, messages := range mq.pending {
+		total += len(messages)
+	}
+	return total
+}
+
+// GetPendingRecipients returns list of recipients with pending messages
+func (mq *MessageQueue) GetPendingRecipients() []string {
+	mq.mu.RLock()
+	defer mq.mu.RUnlock()
+
+	recipients := make([]string, 0, len(mq.pending))
+	for recipient := range mq.pending {
+		recipients = append(recipients, recipient)
+	}
+	return recipients
+}
+
+// IncrementAttempts increments delivery attempt counter
+func (mq *MessageQueue) IncrementAttempts(msgID string) {
+	mq.mu.Lock()
+	defer mq.mu.Unlock()
+
+	for _, messages := range mq.pending {
+		for _, msg := range messages {
+			if msg.ID == msgID {
+				msg.Attempts++
+				mq.saveToDisk()
+				return
+			}
+		}
+	}
+}
+
+// ShouldForward checks if message should be forwarded (multi-hop routing)
+func (mq *MessageQueue) ShouldForward(msg *QueuedMessage) bool {
+	return msg.Hops < msg.MaxHops && msg.Attempts < msg.MaxAttempts
+}
+
+// saveToDisk persists the queue to disk
+func (mq *MessageQueue) saveToDisk() error {
+	queuePath := filepath.Join(mq.queueDir, "queue.json")
+
+	// Serialize queue
+	data, err := json.MarshalIndent(mq.pending, "", "  ")
+	if err != nil {
+		return fmt.Errorf("failed to marshal queue: %w", err)
+	}
+
+	// TODO: Encrypt if mq.encrypted is true
+	// For now, just save plaintext
+
+	// Write to temp file first (atomic write)
+	tempPath := queuePath + ".tmp"
+	if err := os.WriteFile(tempPath, data, 0600); err != nil {
+		return fmt.Errorf("failed to write queue: %w", err)
+	}
+
+	// Atomic rename
+	if err := os.Rename(tempPath, queuePath); err != nil {
+		return fmt.Errorf("failed to rename queue: %w", err)
+	}
+
+	return nil
+}
+
+// loadFromDisk loads the queue from disk
+func (mq *MessageQueue) loadFromDisk() error {
+	queuePath := filepath.Join(mq.queueDir, "queue.json")
+
+	// Check if file exists
+	if _, err := os.Stat(queuePath); os.IsNotExist(err) {
+		// No existing queue - that's fine
+		return nil
+	}
+
+	// Read file
+	data, err := os.ReadFile(queuePath)
+	if err != nil {
+		return fmt.Errorf("failed to read queue: %w", err)
+	}
+
+	// TODO: Decrypt if mq.encrypted is true
+
+	// Parse JSON
+	if err := json.Unmarshal(data, &mq.pending); err != nil {
+		return fmt.Errorf("failed to unmarshal queue: %w", err)
+	}
+
+	return nil
+}
+
+// cleanupLoop periodically removes old messages
+func (mq *MessageQueue) cleanupLoop() {
+	ticker := time.NewTicker(10 * time.Minute)
+	defer ticker.Stop()
+
+	for range ticker.C {
+		mq.cleanup()
+	}
+}
+
+// cleanup removes expired messages
+func (mq *MessageQueue) cleanup() {
+	mq.mu.Lock()
+	defer mq.mu.Unlock()
+
+	now := time.Now()
+	removed := 0
+
+	for recipient, messages := range mq.pending {
+		// Filter out expired messages
+		validMessages := make([]*QueuedMessage, 0)
+		for _, msg := range messages {
+			// Remove if too old or too many attempts
+			if now.Sub(msg.Timestamp) > mq.maxAge || msg.Attempts >= msg.MaxAttempts {
+				removed++
+				continue
+			}
+			validMessages = append(validMessages, msg)
+		}
+
+		if len(validMessages) > 0 {
+			mq.pending[recipient] = validMessages
+		} else {
+			delete(mq.pending, recipient)
+		}
+	}
+
+	// Clean delivered map (keep only recent entries)
+	for msgID := range mq.delivered {
+		// TODO: Add timestamp to delivered map to clean old entries
+		_ = msgID
+	}
+
+	if removed > 0 {
+		mq.saveToDisk()
+	}
+}
+
+// Clear removes all messages from queue
+func (mq *MessageQueue) Clear() error {
+	mq.mu.Lock()
+	defer mq.mu.Unlock()
+
+	mq.pending = make(map[string][]*QueuedMessage)
+	mq.delivered = make(map[string]bool)
+
+	return mq.saveToDisk()
+}
+
+// SetOnDelivered sets callback for when message is delivered
+func (mq *MessageQueue) SetOnDelivered(callback func(string)) {
+	mq.mu.Lock()
+	defer mq.mu.Unlock()
+	mq.onDelivered = callback
+}
+
+// String returns a string representation
+func (mq *MessageQueue) String() string {
+	mq.mu.RLock()
+	defer mq.mu.RUnlock()
+
+	totalPending := 0
+	for _, messages := range mq.pending {
+		totalPending += len(messages)
+	}
+
+	return fmt.Sprintf("MessageQueue(pending=%d, delivered=%d, recipients=%d)",
+		totalPending, len(mq.delivered), len(mq.pending))
+}