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;
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"?
}
Socket 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:<smtp_verifier@" + myHostName + ">");
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();
}
}
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;
}
}