The Tcpdump Group git mirrors - tcpdump/blob - 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
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24
  25 #include "netdissect.h"
  26 #include "extract.h"
  27
  28 static int
  29 ssh_print_version(netdissect_options *ndo, const u_char *pptr, u_int len)
  30 {
  31         u_int idx = 0;
  32
  33         if ( GET_U_1(pptr+idx) != 'S' )
  34                 return 0;
  35         idx++;
  36         if ( GET_U_1(pptr+idx) != 'S' )
  37                 return 0;
  38         idx++;
  39         if ( GET_U_1(pptr+idx) != 'H' )
  40                 return 0;
  41         idx++;
  42         if ( GET_U_1(pptr+idx) != '-' )
  43                 return 0;
  44         idx++;
  45
  46         while (idx < len) {
  47                 if (GET_U_1(pptr + idx) == '\n') {
  48                         /*
  49                          * LF without CR; end of line.
  50                          * Skip the LF and print the line, with the
  51                          * exception of the LF.
  52                          */
  53                         goto print;
  54                 } else if (GET_U_1(pptr + idx) == '\r') {
  55                         /* CR - any LF? */
  56                         if ((idx+1) >= len) {
  57                                 /* not in this packet */
  58                                 goto trunc;
  59                         }
  60                         if (GET_U_1(pptr + idx + 1) == '\n') {
  61                                 /*
  62                                  * CR-LF; end of line.
  63                                  * Skip the CR-LF and print the line, with
  64                                  * the exception of the CR-LF.
  65                                  */
  66                                 goto print;
  67                         }
  68
  69                         /*
  70                          * CR followed by something else; treat this as
  71                          * if it were binary data and don't print it.
  72                          */
  73                         goto trunc;
  74                 } else if (!isascii(GET_U_1(pptr + idx)) ||
  75                            !isprint(GET_U_1(pptr + idx)) ) {
  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 }