com.darwinsys.mail.SmtpUtils Maven / Gradle / Ivy

package com.darwinsys.mail;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.NoRouteToHostException;
import java.net.Socket;
import java.net.UnknownHostException;

import javax.naming.NamingException;

import com.darwinsys.net.DNSUtils;

public class SmtpUtils {
	private String myDnsServer;
	public static final int SMTP_PORT = 25;
	private String myHostName;
	
	public SmtpUtils(String myHostName, String myDnsServer) {
		this.myHostName = myHostName;
		this.myDnsServer= myDnsServer;
	}

	public boolean verifySender(final String user, final String host) throws IOException{
		PrintWriter out = null;
		Socket s = null;
		try {
			String mxHost = null;
			try {
				mxHost = new DNSUtils(myDnsServer).findMX(host);
			} catch (NamingException e) {
				System.out.println("verifySender: cannot vrfy MX");
				return false; // Should be trinary, for "unknown"?
			}
			s = new Socket(mxHost, SMTP_PORT);
			BufferedReader in = new BufferedReader(new InputStreamReader(s.getInputStream()));
			out = new PrintWriter(s.getOutputStream(), true);
			String greeting = readLine(in);
			if (greeting != null) {
				System.out.println(greeting);
			}
			send(out, "HELO " + myHostName);
			String heloResp = readLine(in);
			if (heloResp != null) {
				System.out.println(heloResp);
			}
			send(out, "MAIL From:");
			String mailResp = readLine(in);
			if (mailResp != null) {
				System.out.println(mailResp);
			}
			String errorUser="postmaster";
			send(out, "RCPT To:<" + errorUser + "@" + host + ">");
			String vrfyResp = readLine(in);
			if (vrfyResp == null) {
				throw new IllegalStateException("Read Null Line in middle of SMTP conversation");
			}
			if (vrfyResp.startsWith("550")) {
				return false;
			}
			
			send(out, "QUIT");
			String quitResp = readLine(in);
			if (quitResp != null) {
				System.out.println(quitResp);
			}
			
			return true;
		} catch (UnknownHostException e) {
			return false;
		} catch (NoRouteToHostException e) {
			return false;
		
		} finally {
			if (out != null) {
				out.close();
			}
			if (s != null) {
				s.close();
			}
		}
	}
	public static void send(PrintWriter out, String mesg) {
		System.out.print(">>> ");
		System.out.print(mesg);
		System.out.println(" <<<");
		out.print(mesg + "\r\n");
		out.flush();
	}
	public static String readLine(BufferedReader is) throws IOException {
		String response = is.readLine();
		System.out.print("<<< ");
		System.out.println(response);
		return response;
	}
}