added account

auth/auth.go

@@ -0,0 +1,99 @@
+package auth
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"errors"
+	"time"
+
+	"golang.org/x/crypto/bcrypt"
+)
+
+const (
+	// BCrypt cost - 12 is a good balance between security and performance
+	bcryptCost = 12
+	// Session token length in bytes (32 bytes = 256 bits)
+	sessionTokenLength = 32
+	// Session expiry duration (7 days)
+	sessionExpiry = 7 * 24 * time.Hour
+)
+
+var (
+	ErrInvalidCredentials = errors.New("invalid email or password")
+	ErrUserExists         = errors.New("user already exists")
+	ErrInvalidSession     = errors.New("invalid or expired session")
+	ErrWeakPassword       = errors.New("password must be at least 8 characters")
+	ErrInvalidEmail       = errors.New("invalid email format")
+)
+
+// HashPassword securely hashes a password using bcrypt
+func HashPassword(password string) (string, error) {
+	if len(password) < 8 {
+		return "", ErrWeakPassword
+	}
+
+	hash, err := bcrypt.GenerateFromPassword([]byte(password), bcryptCost)
+	if err != nil {
+		return "", err
+	}
+
+	return string(hash), nil
+}
+
+// CheckPassword verifies a password against a hash
+func CheckPassword(password, hash string) bool {
+	err := bcrypt.CompareHashAndPassword([]byte(hash), []byte(password))
+	return err == nil
+}
+
+// GenerateSessionToken creates a cryptographically secure random token
+func GenerateSessionToken() (string, error) {
+	bytes := make([]byte, sessionTokenLength)
+	_, err := rand.Read(bytes)
+	if err != nil {
+		return "", err
+	}
+
+	// Use URL-safe base64 encoding
+	token := base64.URLEncoding.EncodeToString(bytes)
+	return token, nil
+}
+
+// GetSessionExpiry returns the expiry time for a new session
+func GetSessionExpiry() time.Time {
+	return time.Now().Add(sessionExpiry)
+}
+
+// ValidateEmail performs basic email validation
+func ValidateEmail(email string) bool {
+	if len(email) < 3 || len(email) > 254 {
+		return false
+	}
+
+	// Basic check for @ symbol and domain
+	atCount := 0
+	dotAfterAt := false
+	atPos := -1
+
+	for i, c := range email {
+		if c == '@' {
+			atCount++
+			atPos = i
+		}
+		if atPos > 0 && i > atPos && c == '.' {
+			dotAfterAt = true
+		}
+	}
+
+	return atCount == 1 && dotAfterAt && atPos > 0 && atPos < len(email)-2
+}
+
+// SanitizeInput removes dangerous characters for basic XSS prevention
+// Note: Go templates auto-escape, but this adds an extra layer
+func SanitizeInput(input string) string {
+	// Templates handle escaping, but we can enforce length limits
+	if len(input) > 1000 {
+		return input[:1000]
+	}
+	return input
+}