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Java > Open Source Codes > kawa > TelnetInputStream


1 package kawa; // For now
2 import java.io.*;
3
4 /**
5  * An input stream that handles the telnet protocol.
6  * It handles the special telnet sequences starting with the
7  * "Interpret As Command".(IAC==255) byte.
8  */
9
10 public class TelnetInputStream extends FilterInputStream
11 {
12   Telnet connection;
13
14   public TelnetInputStream (InputStream in, Telnet conn)
15     throws IOException
16   {
17     super(in);
18     buf = new byte[512];
19     this.connection = conn;
20   }
21
22   protected byte[] buf;
23
24   int pos;
25   int count;
26
27   /** The state of control bytes we have seen. */
28   int state = 0;
29
30   int subCommandLength = 0;
31
32   static final int SB_IAC = 400;
33
34   public int read () throws IOException
35   {
36     for (;;)
37       {
38     if (pos >= count)
39           {
40         int avail = in.available();
41         if (avail <= 0)
42           avail = 1;
43         else if (avail > buf.length - subCommandLength)
44           {
45         avail = buf.length - subCommandLength; // FIXME
46 }
47         avail = in.read(buf, subCommandLength, avail);
48         pos = subCommandLength;
49         count = avail;
50         if (avail <= 0)
51           return -1;
52       }
53     int ch = buf[pos++] & 0xff;
54     if (state == 0)
55       {
56         if (ch != Telnet.IAC)
57           return ch;
58         state = Telnet.IAC;
59         continue;
60       }
61     else if (state == Telnet.IAC)
62       {
63         if (ch == Telnet.IAC)
64           {
65         state = 0;
66         return Telnet.IAC;
67           }
68         else if (ch == Telnet.WILL
69              || ch == Telnet.WONT
70              || ch == Telnet.DO
71              || ch == Telnet.DONT
72              || ch == Telnet.SB)
73           {
74         state = ch;
75           }
76         else if (ch == Telnet.IP)
77           {
78         System.err.println("Interrupt Process");
79         state = 0;
80           }
81         else if (ch == Telnet.EOF)
82           {
83         return -1;
84           }
85         else
86           {
87         state = 0; // ???
88 }
89       }
90     else if (state == Telnet.WILL || state == Telnet.WONT
91          || state == Telnet.DO || state == Telnet.DONT)
92       {
93         connection.handle (state, ch);
94         state = 0;
95       }
96     else if (state == Telnet.SB)
97       {
98         if (ch == Telnet.IAC)
99           state = SB_IAC;
100         else
101           buf[subCommandLength++] = (byte) ch;
102       }
103     else if (state == SB_IAC)
104       {
105         if (ch == Telnet.IAC)
106           {
107         buf[subCommandLength++] = (byte) ch;
108         state = Telnet.SB;
109           }
110         else if (ch == Telnet.SE)
111           {
112         connection.subCommand(buf, 0, subCommandLength);
113         state = 0;
114         subCommandLength = 0;
115           }
116         else // Error?
117 {
118         state = 0;
119         subCommandLength = 0;
120           }
121       }
122     else
123       System.err.println("Bad state "+state);
124       }
125   }
126
127   public int read (byte[] b, int offset, int length) throws IOException
128   {
129     if (length <= 0)
130       return 0;
131     int done = 0;
132     if (state != 0 || pos >= count)
133       {
134     int ch = read();
135     if (ch < 0)
136       return ch;
137     b[offset++] = (byte) ch;
138     done++;
139       }
140     if (state == 0)
141       {
142     while (pos < count && done < length)
143       {
144         byte ch = buf[pos];
145         if (ch == (byte) Telnet.IAC)
146           break;
147         b[offset++] = ch;
148         done++;
149         pos++;
150       }
151       }
152     return done;
153   }
154 }
155
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