public static void main(String[] args) {
BufferedReader sysIn =
new BufferedReader(new InputStreamReader(System.in)); // Read from console
PrintStream sysOut = System.out; // Print to console
SSLSocketFactory mainFactory =
(SSLSocketFactory) SSLSocketFactory.getDefault(); // Get default SSL socket factory
try {
SSLSocket clientSocket =
(SSLSocket)
mainFactory.createSocket(
"pop.mail.yahoo.com", 995); // create, connect, start handshake
printSocketInfo(clientSocket); // Print connection info
BufferedWriter serverWriter =
new BufferedWriter(
new OutputStreamWriter(clientSocket.getOutputStream())); // Write to server
BufferedReader serverReader =
new BufferedReader(
new InputStreamReader(clientSocket.getInputStream())); // Read from server
String serverInput = null; // Stores latest line from server
String userInput = ""; // Stores lastest input line from user
boolean tryRead =
true; // Whether to read next line from serverReader (prevents blocking on multiline SMTP
// responses)
// The below booleans, used to successully close the connection, might be unnecessary
boolean quitUser = false; // Whether the user has entered quit, might be unnecessary
boolean openRead = true; // Whether serverReader is still open (serverInput != null)
boolean openSocket = true; // Whether clientSocket is still open (clientSocket != null)
// SMTP input variables
boolean sendingData = false;
boolean multi = false;
// Main connection loop
while (openSocket && openRead && !quitUser) {
if (clientSocket == null) { // Break if socket is closed
openSocket = false;
break;
}
// Display server response/message
if (multi) {
while (tryRead) {
serverInput = serverReader.readLine();
if (serverInput == null) { // If serverReader gets closed/connection broken
openRead = false;
tryRead = false;
break;
}
sysOut.println(serverInput);
// Check for multiline response or error
if (serverInput.equals(".")
|| (serverInput.length() >= 4 && serverInput.startsWith("-ERR"))) {
tryRead = false;
} else {
tryRead = true;
}
}
} else {
serverInput = serverReader.readLine();
if (serverInput == null) { // If serverReader gets closed/connection broken
openRead = false;
tryRead = false;
break;
}
sysOut.println(serverInput);
}
multi = false;
// Exit client if connection lost/closed prematurely
if (openSocket == false || openRead == false) {
break;
}
// If user previously entered quit
if (userInput.length() >= 4 && userInput.substring(0, 4).equalsIgnoreCase("quit")) {
quitUser = true;
break;
}
// Get user input
userInput = ""; // Reset userInput to show prompt
// Read user input, display prompt if blank enter, otherwise send to server
while (userInput.equals("")) {
sysOut.print("C: ");
userInput = sysIn.readLine();
}
serverWriter.write(userInput, 0, userInput.length()); // Writing to server
serverWriter.newLine();
serverWriter.flush();
tryRead = true;
// Prepare for multi-line response if list, uidl, retr, or top
if (userInput.equalsIgnoreCase("list")
|| userInput.equalsIgnoreCase("uidl")
|| userInput.equalsIgnoreCase("auth")
|| (userInput.length() >= 4 && userInput.substring(0, 4).equalsIgnoreCase("capa"))
|| (userInput.length() >= 4 && userInput.substring(0, 4).equalsIgnoreCase("retr"))
|| (userInput.length() >= 4 && userInput.substring(0, 3).equalsIgnoreCase("top"))) {
multi = true;
}
}
// Clean up all connection objects
serverWriter.close();
serverReader.close();
clientSocket.close();
sysIn.close();
sysOut.close();
} catch (IOException e) {
System.err.println(e.toString());
}
}
