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 #include <config.h>
  17
  18 #include "netdissect-stdinc.h"
  19 #include "netdissect-ctype.h"
  20
  21 #include "netdissect.h"
  22 #include "extract.h"
  23
  24 static int
  25 ssh_print_version(netdissect_options *ndo, const u_char *pptr, u_int len)
  26 {
  27         u_int idx = 0;
  28
  29         if ( GET_U_1(pptr+idx) != 'S' )
  30                 return 0;
  31         idx++;
  32         if ( GET_U_1(pptr+idx) != 'S' )
  33                 return 0;
  34         idx++;
  35         if ( GET_U_1(pptr+idx) != 'H' )
  36                 return 0;
  37         idx++;
  38         if ( GET_U_1(pptr+idx) != '-' )
  39                 return 0;
  40         idx++;
  41
  42         while (idx < len) {
  43                 u_char c;
  44
  45                 c = GET_U_1(pptr + idx);
  46                 if (c == '\n') {
  47                         /*
  48                          * LF without CR; end of line.
  49                          * Skip the LF and print the line, with the
  50                          * exception of the LF.
  51                          */
  52                         goto print;
  53                 } else if (c == '\r') {
  54                         /* CR - any LF? */
  55                         if ((idx+1) >= len) {
  56                                 /* not in this packet */
  57                                 goto trunc;
  58                         }
  59                         if (GET_U_1(pptr + idx + 1) == '\n') {
  60                                 /*
  61                                  * CR-LF; end of line.
  62                                  * Skip the CR-LF and print the line, with
  63                                  * the exception of the CR-LF.
  64                                  */
  65                                 goto print;
  66                         }
  67
  68                         /*
  69                          * CR followed by something else; treat this as
  70                          * if it were binary data and don't print it.
  71                          */
  72                         goto trunc;
  73                 } else if (!ND_ASCII_ISPRINT(c) ) {
  74                         /*
  75                          * Not a printable ASCII character; treat this
  76                          * as if it were binary data and don't print it.
  77                          */
  78                         goto trunc;
  79                 }
  80                 idx++;
  81         }
  82 trunc:
  83         return -1;
  84 print:
  85         ND_PRINT(": ");
  86         nd_print_protocol_caps(ndo);
  87         ND_PRINT(": %.*s", (int)idx, pptr);
  88         return idx;
  89 }
  90
  91 void
  92 ssh_print(netdissect_options *ndo, const u_char *pptr, u_int len)
  93 {
  94         ndo->ndo_protocol = "ssh";
  95
  96         ssh_print_version(ndo, pptr, len);
  97 }