[NET-334] org.apache.commons.net.io.FromNetASCIIInputStream can throw a NullPointerException

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0
• Fix Version/s: 2.2

Environment

OS: Linux – Redhat enterprise
JVM 1.6 64bit

• Assignee: Unassigned
• Reporter: Kenneth Ritch
• Created: 12/Aug/10 02:42
• Updated: 04/Jun/11 19:25
• Resolved: 15/Oct/10 12:48

Description

org.apache.commons.net.io.FromNetASCIIInputStream.available() can throw a NullPointerException if the
InputStream is null. This has been experienced on a loaded system.

StackTrace:

Exception in thread "Telnet Reader" java.lang.NullPointerException
at org.apache.commons.net.io.FromNetASCIIInputStream.available(FromNetASCIIInputStream.java:202)
at org.apache.commons.net.io.FromNetASCIIInputStream.read(FromNetASCIIInputStream.java:164)
at java.io.BufferedInputStream.fill(Unknown Source)
at java.io.BufferedInputStream.read(Unknown Source)
at org.apache.commons.net.telnet.TelnetInputStream.__read(TelnetInputStream.java:122)
at org.apache.commons.net.telnet.TelnetInputStream.read(TelnetInputStream.java:375)
at org.apache.commons.net.telnet.TelnetInputStream.read(TelnetInputStream.java:492)
at java.io.BufferedInputStream.fill(Unknown Source)
at java.io.BufferedInputStream.read1(Unknown Source)
at java.io.BufferedInputStream.read(Unknown Source)
at java.io.FilterInputStream.read(Unknown Source)

Cause:

The base PushbackInputStream checks the input stream is not closed before invoking avilable()

274 public int available() throws IOException

{ 275 ensureOpen(); 276 return (buf.length - pos) + super.available(); 277 }

Which throws appropriate IOException if input stream is null:

72 private void ensureOpen() throws IOException

{ 73 if (in == null) 74 throw new IOException("Stream closed"); 75 }

commons.net.io.FromNetASCIIInputStream does not. This can lead to a NullPointerException being thrown if the input stream is null.

191 // PushbackInputStream in JDK 1.1.3 returns the wrong thing
192 /***
193 * Returns the number of bytes that can be read without blocking EXCEPT
194 * when newline conversions have to be made somewhere within the
195 * available block of bytes. In other words, you really should not
196 * rely on the value returned by this method if you are trying to avoid
197 * blocking.
198 ***/
199 @Override
200 public int available() throws IOException
201

{ 202 return (buf.length - pos) + in.available(); 203 }

FromNetASCIIInputStream.available() should be changed to mimic the base class behaviour.