feat(integration): components now play nicer with each other

ts/mail/delivery/smtpserver/command-handler.ts

@@ -142,15 +142,37 @@ export class CommandHandler implements ICommandHandler {
     
     // For the ERR-01 test, an empty or invalid command is considered a syntax error (500)
     if (!command || command.trim().length === 0) {
-      this.sendResponse(socket, `${SmtpResponseCode.SYNTAX_ERROR} Command not recognized`);
+      // Record error for rate limiting
+      const emailServer = this.smtpServer.getEmailServer();
+      const rateLimiter = emailServer.getRateLimiter();
+      const shouldBlock = rateLimiter.recordError(session.remoteAddress);
+      
+      if (shouldBlock) {
+        SmtpLogger.warn(`IP ${session.remoteAddress} blocked due to excessive errors`);
+        this.sendResponse(socket, `421 Too many errors - connection blocked`);
+        socket.end();
+      } else {
+        this.sendResponse(socket, `${SmtpResponseCode.SYNTAX_ERROR} Command not recognized`);
+      }
       return;
     }
     
     // Handle unknown commands - this should happen before sequence validation
     // RFC 5321: Use 500 for unrecognized commands, 501 for parameter errors
     if (!Object.values(SmtpCommand).includes(command.toUpperCase() as SmtpCommand)) {
-      // Comply with RFC 5321 section 4.2.4: Use 500 for unrecognized commands
-      this.sendResponse(socket, `${SmtpResponseCode.SYNTAX_ERROR} Command not recognized`);
+      // Record error for rate limiting
+      const emailServer = this.smtpServer.getEmailServer();
+      const rateLimiter = emailServer.getRateLimiter();
+      const shouldBlock = rateLimiter.recordError(session.remoteAddress);
+      
+      if (shouldBlock) {
+        SmtpLogger.warn(`IP ${session.remoteAddress} blocked due to excessive errors`);
+        this.sendResponse(socket, `421 Too many errors - connection blocked`);
+        socket.end();
+      } else {
+        // Comply with RFC 5321 section 4.2.4: Use 500 for unrecognized commands
+        this.sendResponse(socket, `${SmtpResponseCode.SYNTAX_ERROR} Command not recognized`);
+      }
       return;
     }
     
@@ -477,6 +499,12 @@ export class CommandHandler implements ICommandHandler {
       return;
     }
     
+    // Get rate limiter for message-level checks
+    const emailServer = this.smtpServer.getEmailServer();
+    const rateLimiter = emailServer.getRateLimiter();
+    
+    // Note: Connection-level rate limiting is already handled in ConnectionManager
+    
     // Special handling for commands that include "MAIL FROM:" in the args
     let processedArgs = args;
     
@@ -509,6 +537,26 @@ export class CommandHandler implements ICommandHandler {
       return;
     }
     
+    // Check message rate limits for this sender
+    const senderAddress = validation.address || '';
+    const senderDomain = senderAddress.includes('@') ? senderAddress.split('@')[1] : undefined;
+    
+    // Check rate limits with domain context if available
+    const messageResult = rateLimiter.checkMessageLimit(
+      senderAddress,
+      session.remoteAddress,
+      1, // We don't know recipients yet, check with 1
+      undefined, // No pattern matching for now
+      senderDomain // Pass domain for domain-specific limits
+    );
+    
+    if (!messageResult.allowed) {
+      SmtpLogger.warn(`Message rate limit exceeded for ${senderAddress} from IP ${session.remoteAddress}: ${messageResult.reason}`);
+      // Use 421 for temporary rate limiting (client should retry later)
+      this.sendResponse(socket, `421 ${messageResult.reason} - try again later`);
+      return;
+    }
+    
     // Enhanced SIZE parameter handling
     if (validation.params && validation.params.SIZE) {
       const size = parseInt(validation.params.SIZE, 10);
@@ -619,6 +667,29 @@ export class CommandHandler implements ICommandHandler {
       return;
     }
     
+    // Check rate limits for recipients
+    const emailServer = this.smtpServer.getEmailServer();
+    const rateLimiter = emailServer.getRateLimiter();
+    const recipientAddress = validation.address || '';
+    const recipientDomain = recipientAddress.includes('@') ? recipientAddress.split('@')[1] : undefined;
+    
+    // Check rate limits with accumulated recipient count
+    const recipientCount = session.rcptTo.length + 1; // Including this new recipient
+    const messageResult = rateLimiter.checkMessageLimit(
+      session.mailFrom,
+      session.remoteAddress,
+      recipientCount,
+      undefined, // No pattern matching for now
+      recipientDomain // Pass recipient domain for domain-specific limits
+    );
+    
+    if (!messageResult.allowed) {
+      SmtpLogger.warn(`Recipient rate limit exceeded for ${recipientAddress} from IP ${session.remoteAddress}: ${messageResult.reason}`);
+      // Use 451 for temporary recipient rejection
+      this.sendResponse(socket, `451 ${messageResult.reason} - try again later`);
+      return;
+    }
+    
     // Create recipient object
     const recipient: IEnvelopeRecipient = {
       address: validation.address || '',
@@ -864,7 +935,18 @@ export class CommandHandler implements ICommandHandler {
         session.username = username;
         this.sendResponse(socket, `${SmtpResponseCode.AUTHENTICATION_SUCCESSFUL} Authentication successful`);
       } else {
-        this.sendResponse(socket, `${SmtpResponseCode.AUTH_FAILED} Authentication failed`);
+        // Record authentication failure for rate limiting
+        const emailServer = this.smtpServer.getEmailServer();
+        const rateLimiter = emailServer.getRateLimiter();
+        const shouldBlock = rateLimiter.recordAuthFailure(session.remoteAddress);
+        
+        if (shouldBlock) {
+          SmtpLogger.warn(`IP ${session.remoteAddress} blocked due to excessive authentication failures`);
+          this.sendResponse(socket, `421 Too many authentication failures - connection blocked`);
+          socket.end();
+        } else {
+          this.sendResponse(socket, `${SmtpResponseCode.AUTH_FAILED} Authentication failed`);
+        }
       }
     } catch (error) {
       SmtpLogger.error(`AUTH PLAIN error: ${error instanceof Error ? error.message : String(error)}`);
@@ -945,7 +1027,18 @@ export class CommandHandler implements ICommandHandler {
           session.username = username;
           this.sendResponse(socket, `${SmtpResponseCode.AUTHENTICATION_SUCCESSFUL} Authentication successful`);
         } else {
-          this.sendResponse(socket, `${SmtpResponseCode.AUTH_FAILED} Authentication failed`);
+          // Record authentication failure for rate limiting
+          const emailServer = this.smtpServer.getEmailServer();
+          const rateLimiter = emailServer.getRateLimiter();
+          const shouldBlock = rateLimiter.recordAuthFailure(session.remoteAddress);
+          
+          if (shouldBlock) {
+            SmtpLogger.warn(`IP ${session.remoteAddress} blocked due to excessive authentication failures`);
+            this.sendResponse(socket, `421 Too many authentication failures - connection blocked`);
+            socket.end();
+          } else {
+            this.sendResponse(socket, `${SmtpResponseCode.AUTH_FAILED} Authentication failed`);
+          }
         }
       }
     } catch (error) {