Implement comment length and IP rate limiting in comment creation

server/api/comment.go

@@ -38,7 +38,7 @@ func createComment(c fiber.Ctx) error {
 		return model.NewRequestError("Content cannot be empty")
 	}
 
-	comment, err := service.CreateComment(req, userID, uint(resourceID))
+	comment, err := service.CreateComment(req, userID, uint(resourceID), c.IP())
 	if err != nil {
 		return err
 	}

server/service/comment.go

@@ -3,12 +3,20 @@ package service
 import (
 	"nysoure/server/dao"
 	"nysoure/server/model"
+	"nysoure/server/utils"
+	"time"
 
 	"github.com/gofiber/fiber/v3/log"
 )
 
 const (
 	maxImagePerComment = 9
+	maxCommentsPerIP   = 512  // Maximum number of comments allowed per IP address per day
+	maxCommentLength   = 1024 // Maximum length of a comment
+)
+
+var (
+	commentsLimiter = utils.NewRequestLimiter(maxCommentsPerIP, 24*time.Hour)
 )
 
 type CommentRequest struct {
@@ -16,7 +24,19 @@ type CommentRequest struct {
 	Images  []uint `json:"images"`
 }
 
-func CreateComment(req CommentRequest, userID uint, resourceID uint) (*model.CommentView, error) {
+func CreateComment(req CommentRequest, userID uint, resourceID uint, ip string) (*model.CommentView, error) {
+	if !commentsLimiter.AllowRequest(ip) {
+		log.Warnf("IP %s has exceeded the comment limit of %d comments per day", ip, maxCommentsPerIP)
+		return nil, model.NewRequestError("Too many comments from this IP address, please try again later")
+	}
+
+	if len(req.Content) == 0 {
+		return nil, model.NewRequestError("Content cannot be empty")
+	}
+	if len([]rune(req.Content)) > maxCommentLength {
+		return nil, model.NewRequestError("Comment content exceeds maximum length of 1024 characters")
+	}
+
 	if len(req.Images) > maxImagePerComment {
 		return nil, model.NewRequestError("Too many images, maximum is 9")
 	}
@@ -83,6 +103,13 @@ func ListCommentsWithUser(username string, page int) ([]model.CommentWithResourc
 }
 
 func UpdateComment(commentID, userID uint, req CommentRequest) (*model.CommentView, error) {
+	if len(req.Content) == 0 {
+		return nil, model.NewRequestError("Content cannot be empty")
+	}
+	if len([]rune(req.Content)) > maxCommentLength {
+		return nil, model.NewRequestError("Comment content exceeds maximum length of 1024 characters")
+	}
+
 	if len(req.Images) > maxImagePerComment {
 		return nil, model.NewRequestError("Too many images, maximum is 9")
 	}

server/service/image.go

@@ -11,7 +11,6 @@ import (
 	"nysoure/server/utils"
 	"os"
 	"strconv"
-	"sync"
 	"time"
 
 	"github.com/gofiber/fiber/v3/log"
@@ -55,39 +54,11 @@ func init() {
 }
 
 var (
-	imageUploadsByIP = make(map[string]uint)
-	imageUploadsLock = sync.RWMutex{}
+	imageLimiter = utils.NewRequestLimiter(maxUploadsPerIP, 24*time.Hour)
 )
 
 const maxUploadsPerIP = 100
 
-func init() {
-	// Initialize the map with a cleanup function to remove old entries
-	go func() {
-		for {
-			time.Sleep(24 * time.Hour) // Cleanup every 24 hours
-			imageUploadsLock.Lock()
-			imageUploadsByIP = make(map[string]uint) // Clear the map
-			imageUploadsLock.Unlock()
-		}
-	}()
-}
-
-func addIpUploadCount(ip string) bool {
-	imageUploadsLock.Lock()
-	defer imageUploadsLock.Unlock()
-
-	count, exists := imageUploadsByIP[ip]
-	if !exists {
-		count = 0
-	}
-	if count >= maxUploadsPerIP {
-		return false // Exceeded upload limit for this IP
-	}
-	imageUploadsByIP[ip] = count + 1
-	return true // Upload count incremented successfully
-}
-
 func CreateImage(uid uint, ip string, data []byte) (uint, error) {
 	canUpload, err := checkUserCanUpload(uid)
 	if err != nil {
@@ -96,7 +67,7 @@ func CreateImage(uid uint, ip string, data []byte) (uint, error) {
 	}
 	if !canUpload {
 		// For a normal user, check the IP upload limit
-		if !addIpUploadCount(ip) {
+		if !imageLimiter.AllowRequest(ip) {
 			return 0, model.NewUnAuthorizedError("You have reached the maximum upload limit")
 		}
 	}

server/utils/request_limit.go

@@ -0,0 +1,54 @@
+package utils
+
+import (
+	"sync"
+	"time"
+)
+
+type RequestLimiter struct {
+	limit        int
+	requestsByIP map[string]int
+	mu           sync.Mutex
+}
+
+func NewRequestLimiter(limit int, duration time.Duration) *RequestLimiter {
+	l := &RequestLimiter{
+		limit:        limit,
+		requestsByIP: make(map[string]int),
+	}
+
+	if duration > 0 {
+		go func() {
+			for {
+				time.Sleep(duration)
+				l.resetCounts()
+			}
+		}()
+	}
+
+	return l
+}
+
+func (rl *RequestLimiter) AllowRequest(ip string) bool {
+	rl.mu.Lock()
+	defer rl.mu.Unlock()
+
+	count, exists := rl.requestsByIP[ip]
+	if !exists {
+		count = 0
+	}
+
+	if count >= rl.limit {
+		return false // Exceeded request limit for this IP
+	}
+
+	rl.requestsByIP[ip] = count + 1
+	return true // Request allowed
+}
+
+func (rl *RequestLimiter) resetCounts() {
+	rl.mu.Lock()
+	defer rl.mu.Unlock()
+
+	rl.requestsByIP = make(map[string]int) // Reset all counts
+}