Fix the java.lang.StringIndexOutOfBoundsException that occurs when an SMTP server closes the connection early or returns an empty line.

Fix the same error in the Pop3 UIDL parser.

src/com/android/email/mail/store/Pop3Store.java

@@ -511,6 +511,9 @@ public class Pop3Store extends Store {
              */
             public boolean parseSingleLine(String response) {
                 mErr = false;
+                if (response == null || response.length() == 0) {
+                    return false;
+                }
                 char first = response.charAt(0);
                 if (first == '+') {
                     String[] uidParts = response.split(" +");
@@ -536,6 +539,9 @@ public class Pop3Store extends Store {
              */
             public boolean parseMultiLine(String response) {
                 mErr = false;
+                if (response == null || response.length() == 0) {
+                    return false;
+                }
                 char first = response.charAt(0);
                 if (first == '.') {
                     mEndOfMessage = true;

src/com/android/email/mail/transport/SmtpSender.java

@@ -280,9 +280,11 @@ public class SmtpSender extends Sender {
             result += line.substring(3);
         }
 
-        char c = result.charAt(0);
-        if ((c == '4') || (c == '5')) {
-            throw new MessagingException(result);
+        if (result.length() > 0) {
+            char c = result.charAt(0);
+            if ((c == '4') || (c == '5')) {
+                throw new MessagingException(result);
+            }
         }
 
         return result;

tests/src/com/android/email/mail/store/Pop3StoreUnitTests.java

@@ -104,6 +104,42 @@ public class Pop3StoreUnitTests extends AndroidTestCase {
         assertTrue(parser.mErr);
     }
     
+    /**
+     * Test various rainy-day operations of the UIDL parser for multi-line responses
+     * TODO other malformed responses
+     */
+    public void testUIDLParserMultiFail() {
+        // multi-line mode
+        Pop3Store.Pop3Folder.UidlParser parser = mFolder.new UidlParser();
+        
+        // Test with null input
+        boolean result;
+        result = parser.parseMultiLine(null);
+        assertFalse(result);
+        
+        // Test with empty input
+        result = parser.parseMultiLine("");
+        assertFalse(result);
+    }
+    
+    /**
+     * Test various rainy-day operations of the UIDL parser for single-line responses
+     * TODO other malformed responses
+     */
+    public void testUIDLParserSingleFail() {
+        // single-line mode
+        Pop3Store.Pop3Folder.UidlParser parser = mFolder.new UidlParser();
+        
+        // Test with null input
+        boolean result;
+        result = parser.parseSingleLine(null);
+        assertFalse(result);
+        
+        // Test with empty input
+        result = parser.parseSingleLine("");
+        assertFalse(result);
+    }
+    
     /**
      * Tests that variants on the RFC-specified formatting of UIDL work properly.
      */

tests/src/com/android/email/mail/transport/SmtpSenderUnitTests.java

@@ -109,6 +109,30 @@ public class SmtpSenderUnitTests extends AndroidTestCase {
         mSender.sendMessage(message);
     }
     
+    /**
+     * Test:  Recover from a server closing early (or returning an empty string)
+     */
+    public void testEmptyLineResponse() throws MessagingException {
+        MockTransport mockTransport = openAndInjectMockTransport();
+        
+        // Since SmtpSender.sendMessage() does a close then open, we need to preset for the open
+        mockTransport.expectClose();
+        
+        // Load up just the bare minimum to expose the error
+        mockTransport.expect(null, "220 MockTransport 2000 Ready To Assist You Peewee");
+        mockTransport.expect("EHLO .*", "");
+        
+        // Now trigger the transmission
+        // Note, a null message is sufficient here, as we won't even get past open()
+        try {
+            mSender.sendMessage(null);
+            fail("Should not be able to send with failed open()");
+        } catch (MessagingException me) {
+            // good - expected
+            // TODO maybe expect a particular exception?
+        }
+    }
+    
     /**
      * Set up a basic MockTransport. open it, and inject it into mStore
      */