telnet.c

   1 #include <stdint.h>
   2 #include <stdio.h>
   3 #include <unistd.h>
   4 #include <sys/socket.h>
   5 #include <pty.h>
   6 #include "sessions.h"
   7 #include "telnet.h"
   8
   9
  10 int translate_telnet_input (char *cbuf, int len, session_info *sess)
  11 {
  12         uint8_t * const buf = (uint8_t*)cbuf;
  13
  14
  15         int i = 0, j = 0;
  16         while (i < len)
  17         {
  18                 // CR
  19                 if (buf[i] == '\r')
  20                 {
  21                         // translate it to LF
  22                         buf[j++] = '\n';
  23
  24                         if (++i >= len) break;  // XXX
  25
  26                         // CR LF and CR 0 are translated to LF
  27                         // translation is already done, so we only have to skip it here
  28                         if (buf[i] == '\n' || buf[i] == 0) i++;
  29
  30                         continue;
  31                 }
  32
  33                 // telnet command
  34                 if (buf[i] == TN_IAC)
  35                 {
  36                         if (++i >= len) break;  // XXX
  37
  38                         // it's just an escaped data octet
  39                         if (buf[i] == TN_IAC)
  40                         {
  41                                 buf[j++] = buf[i++];
  42                                 continue;
  43                         }
  44
  45                         // some confirmation
  46                         if (buf[i] == TN_WILL || buf[i] == TN_DO)
  47                         {
  48                                 i += 2;         // XXX just skip it for now
  49                         }
  50
  51                         // something is rejected
  52                         if (buf[i] == TN_WONT || buf[i] == TN_DONT)
  53                         {
  54                                 i += 2;         // XXX just skip it for now
  55                         }
  56
  57                         // some subsection begins
  58                         if (buf[i] == TN_SB)
  59                         {
  60                                 if (++i >= len) break;  // XXX
  61
  62                                 // terminal window size
  63                                 if (buf[i] == TN_NAWS)
  64                                 {
  65                                         struct winsize ws;
  66                                         int n1, n2;
  67
  68                                         i++;
  69
  70                                         n1 = buf[i++];
  71                                         if (n1 == TN_IAC) n1 = buf[i++];
  72                                         n2 = buf[i++];
  73                                         if (n2 == TN_IAC) n2 = buf[i++];
  74                                         ws.ws_col = (n1 << 8) | n2;
  75
  76                                         n1 = buf[i++];
  77                                         if (n1 == TN_IAC) n1 = buf[i++];
  78                                         n2 = buf[i++];
  79                                         if (n2 == TN_IAC) n2 = buf[i++];
  80                                         ws.ws_row = (n1 << 8) | n2;
  81
  82                                         if (i + 2 > len) break; // XXX
  83
  84                                         // skip IAC SE
  85                                         i += 2;
  86                                         if (sess != NULL)
  87                                         {
  88                                                 if (sess->pty_master >= 0)
  89                                                 {
  90                                                         ioctl (sess->pty_master, TIOCSWINSZ, &ws);
  91                                                 }
  92
  93                                                 // do not lock mutex, it should be safe
  94                                                 sess->term_wid = ws.ws_col;
  95                                                 sess->term_hgt = ws.ws_row;
  96                                         }
  97
  98                                         continue;
  99                                 }
 100
 101                                 // XXX
 102                         }
 103
 104                         continue;
 105                 }
 106
 107                 // an ordinary octet, just copy it
 108                 buf[j++] = buf[i++];
 109         }
 110
 111         return j;
 112 }
 113
 114
 115
 116 void send_telnet_init (int sck)
 117 {
 118         uint8_t req[] =
 119         {
 120                 TN_IAC, TN_WILL, TN_SUPPRESS_GA,        // enable full-duplex mode (RFC 858)
 121                 TN_IAC, TN_DO, TN_NAWS,                 // request window size info (RFC 1073)
 122                 TN_IAC, TN_WILL, TN_ECHO                // request to disable local echo (RFC 857)
 123         };
 124         send (sck, req, sizeof(req), 0);
 125 }
 126