fix: resource leaks, panics, and improve robustness

- Fix SMTP client leak on reconnection (worker.go)
- Fix computeBackoff panic when Attempts=0 (scheduler.go)
- Replace ValidateURL HTTP request with url.Parse
- Fix break only breaking select not for loop (dispatcher.go)
- Fix AttachmentProcessor opening file twice (template.go)
- Use os.Stat for --text file detection instead of .txt suffix
- Make database path configurable via --db-path flag
- Add MustGetGlobalManager for safe singleton access
- Stop signal channels on exit to prevent goroutine leak
- Fix monitor cleanup waiting arbitrary 5 seconds
- Log malformed CSV rows and file close errors
- Update tests and docs to match new behavior

Author: bravo1goingdark

Makefile

@@ -5,7 +5,7 @@
 BINARY_NAME=mailgrid
 VERSION ?= $(shell git describe --tags --exact-match 2>/dev/null || git rev-parse --short HEAD)
 BUILD_TIME=$(shell date -u +%Y-%m-%dT%H:%M:%SZ)
-LDFLAGS=-s -w -X main.version=$(VERSION) -X main.buildTime=$(BUILD_TIME)
+LDFLAGS=-s -w -X main.version=$(VERSION) -X main.buildTime=$(BUILD_TIME) -X main.commit=$(VERSION)
 
 # Optimization flags for minimal binary size
 BUILD_FLAGS=-ldflags="$(LDFLAGS)" -trimpath

cli/cliargs.go

@@ -48,8 +48,9 @@ type CLIArgs struct {
 	ShowHelp bool // Show help message
 
 	// Offset tracking
-	Resume      bool // Resume from last saved offset
-	ResetOffset bool // Clear offset file and start from beginning
+	Resume      bool   // Resume from last saved offset
+	ResetOffset bool   // Clear offset file and start from beginning
+	DBPath      string // Path to the BoltDB database file
 }
 
 // printHelp prints a custom formatted help message with grouped flags
@@ -152,6 +153,7 @@ func ParseFlags() CLIArgs {
 
 	pflag.BoolVar(&args.Resume, "resume", false, "Resume sending from last saved offset")
 	pflag.BoolVar(&args.ResetOffset, "reset-offset", false, "Clear offset file and start from beginning")
+	pflag.StringVar(&args.DBPath, "db-path", "mailgrid.db", "Path to BoltDB database file for job persistence")
 
 	// Add help flag manually to control behavior
 	pflag.BoolVarP(&showHelp, "help", "h", false, "Show this help message")

cli/runner.go

@@ -41,6 +41,7 @@ func Run(args CLIArgs) error {
 	// Handle graceful shutdown on Ctrl+C / SIGTERM
 	sigChan := make(chan os.Signal, 1)
 	signal.Notify(sigChan, os.Interrupt, syscall.SIGTERM)
+	defer signal.Stop(sigChan)
 	var wg sync.WaitGroup
 	defer wg.Wait()
 
@@ -55,12 +56,12 @@ func Run(args CLIArgs) error {
 
 	// Handle --jobs-list flag
 	if args.ListJobs {
-		return listScheduledJobs(args.EnvPath)
+		return listScheduledJobs(args.DBPath, args.EnvPath)
 	}
 
 	// Handle --jobs-cancel flag
 	if args.CancelJobID != "" {
-		return cancelScheduledJob(args.EnvPath, args.CancelJobID)
+		return cancelScheduledJob(args.DBPath, args.EnvPath, args.CancelJobID)
 	}
 
 	// Run scheduler dispatcher in foreground
@@ -74,7 +75,7 @@ func Run(args CLIArgs) error {
 		// Configure optimized scheduler manager
 		config := scheduler.DefaultOptimizedConfig()
 		managerConfig := scheduler.ManagerConfig{
-			DBPath:          "mailgrid.db",
+			DBPath:          args.DBPath,
 			SMTPConfig:      smtpConfig.SMTP,
 			OptimizedConfig: config,
 			ShutdownDelay:   5 * time.Minute,
@@ -178,7 +179,7 @@ func Run(args CLIArgs) error {
 		}
 
 		fmt.Printf("[SCHEDULE] Job scheduled successfully%s\n", scheduleInfo)
-		fmt.Printf("[DATABASE]  Database: mailgrid.db\n")
+		fmt.Printf("[DATABASE]  Database: %s\n", args.DBPath)
 		fmt.Printf(" The scheduler will start automatically and run in the background\n")
 
 		return nil
@@ -411,12 +412,8 @@ func Run(args CLIArgs) error {
 	// Cleanup monitoring server if it was started
 	if monitorServer != nil {
 		go func() {
-			// Use context with timeout instead of sleep for cleaner shutdown
-			ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-			defer cancel()
-			<-ctx.Done() // Give users time to see final results
 			if err := monitorServer.Stop(); err != nil {
-				log.Printf("️ Failed to stop monitor server: %v", err)
+				log.Printf("Failed to stop monitor server: %v", err)
 			}
 		}()
 	}
@@ -474,12 +471,12 @@ func Run(args CLIArgs) error {
 }
 
 // listScheduledJobs lists all scheduled jobs from the database
-func listScheduledJobs(envPath string) error {
+func listScheduledJobs(dbPath, envPath string) error {
 	if envPath == "" {
 		return fmt.Errorf("config file required (--env)")
 	}
 
-	db, err := database.NewDB("mailgrid.db")
+	db, err := database.NewDB(dbPath)
 	if err != nil {
 		return fmt.Errorf("failed to open database: %w", err)
 	}
@@ -512,15 +509,15 @@ func listScheduledJobs(envPath string) error {
 }
 
 // cancelScheduledJob cancels a scheduled job by ID
-func cancelScheduledJob(envPath, jobID string) error {
+func cancelScheduledJob(dbPath, envPath, jobID string) error {
 	if envPath == "" {
 		return fmt.Errorf("config file required (--env)")
 	}
 	if jobID == "" {
 		return fmt.Errorf("job ID required (--jobs-cancel)")
 	}
 
-	db, err := database.NewDB("mailgrid.db")
+	db, err := database.NewDB(dbPath)
 	if err != nil {
 		return fmt.Errorf("failed to open database: %w", err)
 	}

cli/tasks.go

@@ -64,14 +64,11 @@ func PrepareEmailTasks(recipients []parser.Recipient, templatePath, subjectTpl s
 	return tasks, nil
 }
 
-// HasMissingFields returns true if any field in recipient data is empty.
+// HasMissingFields returns true if the recipient email is empty.
+// Other data fields may be optional depending on the template, so only
+// the email field is required.
 func HasMissingFields(r parser.Recipient) bool {
-	for _, val := range r.Data {
-		if val == "" {
-			return true
-		}
-	}
-	return false
+	return r.Email == ""
 }
 
 // printDryRun logs rendered email content to the console instead of sending.
@@ -179,14 +176,11 @@ func SendSingleEmail(args CLIArgs, cfg config.SMTPConfig) error {
 
 		fmt.Printf("  Monitor dashboard: http://localhost:%d\n", args.MonitorPort)
 
-		// Cleanup monitor after completion with context timeout instead of sleep
+		// Cleanup monitor after completion
 		defer func() {
 			go func() {
-				ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-				defer cancel()
-				<-ctx.Done() // Wait for timeout or cancellation
 				if err := monitorServer.Stop(); err != nil {
-					log.Printf("️ Failed to stop monitor server: %v", err)
+					log.Printf("Failed to stop monitor server: %v", err)
 				}
 			}()
 		}()

cmd/mailgrid/main.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"github.com/bravo1goingdark/mailgrid/cli"
 	"log"
-	"os"
 )
 
 // Version information (set at build time)
@@ -45,5 +44,4 @@ func showVersion() {
 	fmt.Printf("Commit: %s\n", commit)
 	fmt.Printf("\nMailGrid is a production-ready email orchestrator for bulk email campaigns.\n")
 	fmt.Printf("Documentation: https://github.com/bravo1goingdark/mailgrid\n")
-	os.Exit(0)
 }

config/config.go

@@ -31,8 +31,8 @@ func LoadConfig(path string) (*AppConfig, error) {
 	}
 	defer func() {
 		if closeErr := file.Close(); closeErr != nil {
-			// Log error but don't override main function error
-			// This ensures we don't mask the main error if JSON decoding fails
+			// Log to stderr since callers may override the returned error
+			fmt.Fprintf(os.Stderr, "Warning: failed to close config file: %v\n", closeErr)
 		}
 	}()
 

docs/docs.md

@@ -104,14 +104,15 @@ Subject line with template support.
 
 ### `--text`
 
-Plain text body (inline or `.txt` file).
+Plain text body (inline text or path to a file). If the argument points to an existing file, its contents are used; otherwise it's treated as inline text.
 
 ```bash
 # Inline
 --text "Hello world!"
 
-# From file
+# From file (any extension)
 --text ./body.txt
+--text /path/to/message
 ```
 
 ### `--to`
@@ -124,10 +125,13 @@ mailgrid --env config.json --to user@example.com --subject "Hello" --text "Hi!"
 
 ### `--cc` / `--bcc`
 
-CC/BCC recipients (comma-separated or `@file.txt`).
+CC/BCC recipients (comma-separated emails or path to a file with one email per line).
 
 ```bash
+# Inline
 --cc "team@example.com,manager@example.com"
+
+# From file
 --bcc ./bcc_list.txt
 ```
 
@@ -240,6 +244,8 @@ Schedule emails for later or recurring delivery. Jobs persist in BoltDB.
 ```bash
 --job-retries 3                 # Scheduler-level retries (default: 3)
 -J 3
+
+--db-path mailgrid.db           # Path to BoltDB database (default: mailgrid.db)
 ```
 
 ---
@@ -411,3 +417,4 @@ mailgrid --env config.json \
 | `--scheduler-run` | `-R` | false | Run daemon |
 | `--resume` | - | false | Resume campaign |
 | `--reset-offset` | - | false | Clear offset |
+| `--db-path` | - | mailgrid.db | Database path |

email/dispatcher.go

@@ -130,7 +130,7 @@ func StartDispatcher(tasks []Task, cfg config.SMTPConfig, concurrency int, batch
 			case taskChan <- task:
 			case <-ctx.Done():
 				log.Printf("Context cancelled, stopping task dispatch")
-				break
+				return // return instead of break to exit the goroutine
 			}
 		}
 		close(taskChan)

email/template.go

@@ -5,6 +5,7 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"errors"
+	"fmt"
 	"html/template"
 	"io"
 	"mime"
@@ -227,7 +228,8 @@ func NewAttachmentProcessor(maxSize int64) *AttachmentProcessor {
 	}
 }
 
-// ProcessAttachment handles a single attachment efficiently
+// ProcessAttachment handles a single attachment efficiently.
+// It opens the file only once and reuses the handle for both MIME detection and reading.
 func (p *AttachmentProcessor) ProcessAttachment(path string) (io.Reader, string, error) {
 	// Get file info
 	info, err := os.Stat(path)
@@ -240,35 +242,36 @@ func (p *AttachmentProcessor) ProcessAttachment(path string) (io.Reader, string,
 		return nil, "", ErrAttachmentTooLarge
 	}
 
-	// Check MIME type
+	// Open file once
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, "", err
+	}
+
+	// Check MIME type by extension first
 	mimeType := mime.TypeByExtension(filepath.Ext(path))
 	if mimeType == "" {
-		// Try to detect type
-		file, err := os.Open(path)
-		if err != nil {
-			return nil, "", err
+		// Try to detect type from file content
+		buffer := make([]byte, 512)
+		n, readErr := file.Read(buffer)
+		if readErr != nil && readErr != io.EOF {
+			file.Close()
+			return nil, "", readErr
 		}
-		defer file.Close()
+		mimeType = http.DetectContentType(buffer[:n])
 
-		// Read first 512 bytes for MIME detection
-		buffer := make([]byte, 512)
-		_, err = file.Read(buffer)
-		if err != nil && err != io.EOF {
-			return nil, "", err
+		// Seek back to beginning for actual reading
+		if _, seekErr := file.Seek(0, io.SeekStart); seekErr != nil {
+			file.Close()
+			return nil, "", fmt.Errorf("failed to seek file: %w", seekErr)
 		}
-		mimeType = http.DetectContentType(buffer)
 	}
 
 	if _, ok := p.allowedTypes[mimeType]; !ok {
+		file.Close()
 		return nil, "", ErrUnsupportedAttachmentType
 	}
 
-	// Create efficient reader
-	file, err := os.Open(path)
-	if err != nil {
-		return nil, "", err
-	}
-
 	// Use buffered reader from pool
 	buf := p.bufferPool.Get().(*[]byte)
 	reader := bufio.NewReaderSize(file, len(*buf))

email/worker.go

@@ -185,6 +185,10 @@ func processBatch(w worker, client *smtp.Client, batch []Task) {
 		// Check if we need to reconnect (connection lost or auth error)
 		if isConnectionError(err) {
 			log.Printf("[Worker %d] Connection error, attempting reconnection...", w.ID)
+			// Close old client before creating a new one to prevent resource leak
+			if quitErr := client.Quit(); quitErr != nil {
+				log.Printf("[Worker %d] Failed to quit old SMTP session: %v", w.ID, quitErr)
+			}
 			newClient, reconnErr := ConnectSMTPWithContext(w.Ctx, w.Config)
 			if reconnErr != nil {
 				log.Printf("[Worker %d] Reconnection failed: %v", w.ID, reconnErr)