[NET-173] Duplicate IAC when sending a IAC using TelnetClient.getOutputStream()

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Not A Problem
• Affects Version/s: 1.4

Environment

Linux

• Assignee: Unassigned
• Reporter: Scott Burch
• Created: 07/Nov/07 16:37
• Updated: 12/Dec/14 17:17
• Resolved: 12/Dec/14 17:17

Description

TelnetOutputStream.java appears to have a bug that if we send a IAC to the stream returned by TelnetClient.getOutputStream() we get duplicate IAC commands to the telnet server.

I looked through the code and I think I have found the reason.

Line 82-85 appears to just send two IAC commands.
82 case TelnetCommand.IAC:
83 __client._sendByte(TelnetCommand.IAC);
84 __client._sendByte(TelnetCommand.IAC);
85 break;

Line 91-95 appears to send the original character (which is a IAC) and a IAC thus producing two IACs in the stream.
91 else if (ch == TelnetCommand.IAC)
92

{ 93 __client._sendByte(ch); 94 __client._sendByte(TelnetCommand.IAC); 95 }



50 public void write(int ch) throws IOException
51 {
52
53 synchronized (__client)
54 {
55 ch &= 0xff;
56
57 if (__client._requestedWont(TelnetOption.BINARY))
58 {
59 if (__lastWasCR)
60 {
61 if (__convertCRtoCRLF)this
62 {
63 __client._sendByte('\n');
64 if (ch == '\n')
65 { 66 __lastWasCR = false; 67 return ; 68 }
69 }
70 else if (ch != '\n')
71 __client._sendByte('\0');
72 }
73
74 __lastWasCR = false;
75
76 switch (ch)
77 { 78 case '\r': 79 __client._sendByte('\r'); 80 __lastWasCR = true; 81 break; 82 case TelnetCommand.IAC: 83 __client._sendByte(TelnetCommand.IAC); 84 __client._sendByte(TelnetCommand.IAC); 85 break; 86 default: 87 __client._sendByte(ch); 88 break; 89 }
90 }
91 else if (ch == TelnetCommand.IAC)
92 {93 __client._sendByte(ch);94 __client._sendByte(TelnetCommand.IAC);95 }

96 else
97 __client._sendByte(ch);
98 }
99 }

Issue Links

• is related to: NET-89 [net] TelnetClient broken for binary transmissions + solution
• is related to: NET-361 Implement Telnet Command sender