contrib/tcpdump/print-ssh.c

   1 /*
   2  * Redistribution and use in source and binary forms, with or without
   3  * modification, are permitted provided that: (1) source code
   4  * distributions retain the above copyright notice and this paragraph
   5  * in its entirety, and (2) distributions including binary code include
   6  * the above copyright notice and this paragraph in its entirety in
   7  * the documentation or other materials provided with the distribution.
   8  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND
   9  * WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
  10  * LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  11  * FOR A PARTICULAR PURPOSE.
  12  */
  13
  14 /* \summary: Secure Shell (SSH) printer */
  15
  16 #ifdef HAVE_CONFIG_H
  17 #include <config.h>
  18 #endif
  19
  20 #include "netdissect-stdinc.h"
  21 #include "netdissect-ctype.h"
  22
  23 #include "netdissect.h"
  24 #include "extract.h"
  25
  26 static int
  27 ssh_print_version(netdissect_options *ndo, const u_char *pptr, u_int len)
  28 {
  29         u_int idx = 0;
  30
  31         if ( GET_U_1(pptr+idx) != 'S' )
  32                 return 0;
  33         idx++;
  34         if ( GET_U_1(pptr+idx) != 'S' )
  35                 return 0;
  36         idx++;
  37         if ( GET_U_1(pptr+idx) != 'H' )
  38                 return 0;
  39         idx++;
  40         if ( GET_U_1(pptr+idx) != '-' )
  41                 return 0;
  42         idx++;
  43
  44         while (idx < len) {
  45                 u_char c;
  46
  47                 c = GET_U_1(pptr + idx);
  48                 if (c == '\n') {
  49                         /*
  50                          * LF without CR; end of line.
  51                          * Skip the LF and print the line, with the
  52                          * exception of the LF.
  53                          */
  54                         goto print;
  55                 } else if (c == '\r') {
  56                         /* CR - any LF? */
  57                         if ((idx+1) >= len) {
  58                                 /* not in this packet */
  59                                 goto trunc;
  60                         }
  61                         if (GET_U_1(pptr + idx + 1) == '\n') {
  62                                 /*
  63                                  * CR-LF; end of line.
  64                                  * Skip the CR-LF and print the line, with
  65                                  * the exception of the CR-LF.
  66                                  */
  67                                 goto print;
  68                         }
  69
  70                         /*
  71                          * CR followed by something else; treat this as
  72                          * if it were binary data and don't print it.
  73                          */
  74                         goto trunc;
  75                 } else if (!ND_ASCII_ISPRINT(c) ) {
  76                         /*
  77                          * Not a printable ASCII character; treat this
  78                          * as if it were binary data and don't print it.
  79                          */
  80                         goto trunc;
  81                 }
  82                 idx++;
  83         }
  84 trunc:
  85         return -1;
  86 print:
  87         ND_PRINT(": ");
  88         nd_print_protocol_caps(ndo);
  89         ND_PRINT(": %.*s", (int)idx, pptr);
  90         return idx;
  91 }
  92
  93 void
  94 ssh_print(netdissect_options *ndo, const u_char *pptr, u_int len)
  95 {
  96         ndo->ndo_protocol = "ssh";
  97
  98         ssh_print_version(ndo, pptr, len);
  99 }